for RES, Storage and Waste Recovery for efficient ... · FOR RES, STORAGE AND WASTE RECOVERY FOR...

FOR RES, STORAGE & WASTE RECOVERY FOR EFFICIENT MANUFACTURING

TECHNOLOGY ROADMAP

Grant agreement no.

608977

SWOTANALYSIS AND SPECIFIC TECHNOLOGY

RANKING

TECHOLOGY ROADMAP FOR RES, STORAGE AND WASTE RECOVERY FOR EFFICIENT MANUFACTURING

REEMAIN - GA no. 608977

Members of the REEMAIN project

Fundación CARTIF

SCM Group S.p.A.

Galletas Gullón, S.A.

Bossa Ticaret ve Sanayi İşletmeleri T.A.Ş

Solera GmbH

youris.com G.E.I.E.

Fraunhofer IWU – Institute for Machine Tools and

Forming Technology

R2M Solution S.r.l.

EURAC – European Academy

DMU – De Montfort University

EST Enerji

Ikerlan S. Coop.

IES – Integrated Environmental Solutions Limited

CRIT Research

AENOR – Spanish Association for Standardization

and Certification

JER – dr. jakob energy research GmbH & Co. KG


REEMAIN - GA no. 608977 I

Copyright notices

© 2016 REEMAIN Consortium Partners. All rights reserved. REEMAIN has received funding

from the European Union’s Seventh Framework Programme for research, technological

development and demonstration under grant agreement no 608977.

For more information on the project, its partners, and contributors please see

http://www.reemain.eu. You are permitted to copy and distribute verbatim copies of this

document, containing this copyright notice, but modifying this document is not allowed. All

contents are reserved by default and may not be disclosed to third parties without the written

consent of the REEMAIN partners, except as mandated by the European Commission

contract, for reviewing and dissemination purposes. All trademarks and other rights on third

party products mentioned in this document are acknowledged and owned by the respective

holders.

The information contained in this document represents the views of REEMAIN members as

of the date they are published. The REEMAIN consortium does not guarantee that any

information contained herein is error-free, or up to date, nor makes warranties, express,

implied, or statutory, by publishing this document. The information in this document is

provided as is and no guarantee or warranty is given that the information is fit for any

particular purpose. The user thereof uses the information at its sole risk and liability.

The document reflects only the authors’ views and the European Union is not liable for any

use that may be made of the information contained therein.


REEMAIN - GA no. 608977 II

ACKNOWLEDGEMENTS

This Technology Roadmap was elaborated in the framework of the REEMAIN project

GA no. 608977 supported by the FP7 of the European Commission (project duration

01.10.2013 to 30.09.2017). The authors would like to thank the European Commission for

the support of the REEMAIN project as well as the project partners for their contribution to

the roadmap. For the provision of pictures, graphs or data, the authors thank the following

companies and institutes: IEA, AEE Intec, Grammer Solar GmbH, Solimpeks Solar

GmbH i.L., Alstom, General Electric Company, EngineeringToolBox, Renewables First,

CALEFFI S.p.A., Wellons FEI, Dockside Green, Victoria Canada, ZORG Biogas AG, DLR,

Power from the Sun, Hochschule Osnabrück, ZAE Bayern, Turboden S.r.l., Ergion GmbH

i.L., IESO and Ramboll Energy.


REEMAIN - GA no. 608977 III

Title

Technology Roadmap

for RES, Storage and Waste Recovery for efficient manufacturing

Release Date

July 2016

Version

1

Dissemination Level

PU – Public Report

Editor

JER – dr. jakob enery research GmbH & Co. KG

Dr. Uli Jakob, Samuel Baumeister, Johannes Steinbeißer

Authors

Chapter 1 JER Dr. Uli Jakob

Chapter 2.1 CARTIF Fredy Vélez, Javier Antolín, Luis Ángel Bujedo, Jesús Samaniego

DMU Dr. Rick Greenough, Dr. Andy Wright

EURAC Dr. Marco Cozzini

JER Dr. Uli Jakob, Samuel Baumeister

Solera Klemens Jakob, Laura Trujillo

Chapter 2.2 CARTIF Fredy Vélez, Andres Macia

EURAC Dr. Alice Vittoriosi

IKERLAN Iñigo Gandiaga, Maider Usabiaga, Aitor Milo

Solera Klemens Jakob, Laura Trujillo


EURAC Dr. Alice Vittoriosi



CRIT Diego Bartolomé

EURAC Dr. Marco Cozzini


Chapter 3 EURAC Dr. Marco Cozzini


Chapter 4 JER Dr. Uli Jakob


REEMAIN - GA no. 608977 IV

TABLE OF CONTENTS

1. INTRODUCTION ......................................................................................................... 1

2. TECHNOLOGIES ........................................................................................................ 3

2.1. RENEWABLE ENERGY SOURCES ........................................................................... 3

2.1.1. HOT WATER COLLECTORS (LOW TEMPERATURE) ............................................... 3

2.1.2. SOLAR CONCENTRATORS (MEDIUM TEMPERATURE) ........................................... 8

2.1.3. AIR COLLECTORS .......................................................................................... 13

2.1.4. SOLAR PROCESS HEAT .................................................................................. 15

2.1.5. SOLAR COOLING ........................................................................................... 20

2.1.6. PHOTOVOLTAIK ............................................................................................ 23

2.1.7. PHOTOVOLTAIC-THERMAL COLLECTORS ......................................................... 26

2.1.8. CONCENTRATED SOLAR POWER (CSP) .......................................................... 28

2.1.9. WIND TURBINES ............................................................................................ 33

2.1.10. HYDRO ELECTRICITY ..................................................................................... 37

2.1.11. GEOTHERMAL ............................................................................................... 42

2.1.12. BIOMASS ...................................................................................................... 47

2.1.13. COMBINED HEAT AND POWER / CHP (BIOGAS) ................................................ 53

2.1.14. CHP (WOOD PELLETS / CHIPS) ....................................................................... 60

2.2. STORAGE SYSTEMS ........................................................................................... 65

2.2.1. THERMAL ENERGY STORAGE ......................................................................... 65

2.2.2. ICE STORAGES ............................................................................................. 78

2.2.3. PCM STORAGES ........................................................................................... 81

2.2.4. BATTERIE STORAGES .................................................................................... 85

2.3. WASTE HEAT RECOVERY .................................................................................... 89

2.3.1. ORGANIC RANKINE CYCLE (ORC) .................................................................. 89

2.3.2. THERMAL COOLING ....................................................................................... 93

2.3.3. HEAT EXCHANGER ........................................................................................ 98

2.3.4. HEAT PUMP ................................................................................................ 101

2.3.5. WHP SYSTEM (PRESSURE REDUCTION) ....................................................... 107

2.4. ENERGY EFFICIENT HYBRID SYSTEMS ................................................................ 111

2.4.1. COMBINED HEAT AND POWER (NATURAL GAS) ............................................... 111

2.4.2. COMBINED HEAT AND POWER (FUEL CELL) .................................................... 117

2.4.3. CHPC (COMBINED HEAT POWER AND COLD) ................................................ 122

2.4.4. DISTRICT HEATING ...................................................................................... 124

2.4.5. DISTRICT COOLING ..................................................................................... 129


REEMAIN - GA no. 608977 V

3. ASSESSMENT AND RANKING .............................................................................. 132

3.1. METHODOLOGY DESCRIPTION ........................................................................... 132

3.1.1. SWOT ANALYSIS ....................................................................................... 132

3.1.2. TECHNOLOGY RANKING ............................................................................... 132

3.2. RESULTS OF TECHNOLOGY RANKING ................................................................. 140

3.2.1. TECHNOLOGY RANKING FOR CLASSIFICATION CLUSTERS ............................... 140

3.2.2. TECHNOLOGY RANKING FOR GENERATION CLUSTERS .................................... 142

3.2.3. INTERNAL AND EXTERNAL SURVEYS ............................................................. 146

3.3. SENSITIVITY ANALYSIS ..................................................................................... 150

4. SUMMARY .............................................................................................................. 155

LIST OF FIGURES .......................................................................................................... 157

LIST OF TABLES ............................................................................................................ 160

REFERENCES ................................................................................................................ 164


REEMAIN - GA no. 608977 VI

ACRONYMS

CHP Combined Heat and Power MCDA Multi-criteria decision analysis

CHPC Combined Heat Power and Cold MCFC Molten Carbonate Fuel Cells

DC Direct Current MSW Municipal Solid Waste

DC District Cooling MVR Mechanical Vapour Recompression

DEC Desiccant and Evaporative Cooling NG Natural Gas

DH District Heating ODP Ozone Depleting Potential

DHW Domestic Hot Water ORC Organic Rankine Cycle

DLR German Aerospace Center PAFC Phosphoric Acid Fuel Cells

DMU De Montfort University PCM Phase Change Material

DoE Department of Energy PEM Polymer Electrolyte Membrane or Proton

EER Energy Efficiency Ratio Exchange Membrane

EFE External Factor Evaluation matrix PER Primary Energy Ratio

ESS Electric Energy Storage PEST Political, Economic, Social and

EURAC The European Academy of Bolzano Technological

FC Fuel Cell PV Photovoltaic

GHG Greenhouse Gases PVT Photovoltaic Thermal Collector

GRT Ground Response Test R&D Research and Development

GWP Global Warming Potential R2M Research to Market

H2 Hydrogen REE Renewable Energy Efficiency

HAWT Horizontal Axis Wind Turbine RES Renewable Energy Sources

HCFC Hydro-Chlorofluorocarbons RHC Renewable Heating and Cooling

HFC Hydro-Fluorocarbons ROI Return on Investment

HHV Higher Heating Value RPM Revolutions per Minute

HTF Hot Thermal Fluid SOFC Solid Oxide Fuel Cells

HX Heat Exchanger SOFC Solid Oxide Fuel Cells

IEA International Energy Agency SPF Seasonal Performance Factor

IFE Internal Factor Evaluation matrix SWOT Strengths, Weaknesses, Opportunities

IMS Intelligent Manufacturing Systems and Threats

IWU Fraunhofer Institute for Machine Tools and TCS Thermal Chemical Storage

Forming Technology TDHP Thermally Driven Heat Pumps

JER dr. jakob energy research GmbH & Co. KG TES Thermal Energy Storage

LCA Life Cycle Assessment TRL Technology Readiness Level

LCC Life Cycle Costs VAWT Vertical Axis Wind Turbine

LHV Lower heating Value WHP Waste Heat to Power


REEMAIN - GA no. 608977 1

1. INTRODUCTION

Responsible Author:

Dr. Uli Jakob: JER, Weinstadt, Germany

The following roadmap is the public version of Deliverable D3.1 “Technology Roadmap”

from Task T3.1 of the REEMAIN project, which is an FP7 Factory of the Future project

supported by the European Commission und GA no. 608977. The project addresses the

development and demonstration of a methodology and simulation platform likely to boost

the efficiency of both energy and material resources in factories. Therefore, the REEMAIN

project combines cutting edge knowledge and experience from production processes,

energy simulation software tools, energy and resource planning, renewable energy and

storage.

The focus of the technology roadmap lies on the review of innovative renewable energy

sources (RES), storage and waste heat recovery technologies for efficient manufacturing in

a factory environment to reduce and improve the overall conventional energy demand of

production processes. Therefore, energetic solutions mainly related to the three industry

sectors (textile, biscuit and iron casting) of the REEMAIN project were investigated. Different

RES solutions (e.g. solar concentrators for process heat, photovoltaics (PV), wind turbines,

etc.), storage technologies (thermal, electricity, etc.), waste heat recovery solutions (e.g.

ORC, heat exchanger (HX), etc.) and energy efficient hybrid systems (as combination of

RES and waste recovery technologies) are screened and evaluated into clusters (groups of

technologies like heat generation, cold generation, electricity generation, storage, etc.).

Table 1 shows the investigated technologies in the different categories (energy generation

and classification clusters). The road mapping exercise produces a technology dataset or

library of the evaluated technologies. This includes an extensive list of available RES,

storage, and waste heat recovery technologies with a ranking of the most appropriate ones

for the factory environment. The evaluation is based on Strengths Weaknesses

Opportunities and Threats (SWOT) analyses including estimations on Live Cycle Costs

(LCC), Live Cycle Assessment (LCA), carbon reduction (CO2), Return on Investment (ROI),

etc. The dataset includes also a comprehensive description of the evaluated innovative

technologies with a short list of input and output parameters as well as average variables.

The following innovative technologies are identified through the assessment and ranking

within this Technology Roadmap for Efficient Manufacturing as highly interesting

technologies for manufacturing processes depending on different applications:

Electricity generation: Photovoltaic

Heat generation: Solar Thermal Collectors and Solar Concentrators

Cold generation: Solar Cooling systems

Poly generation: ORC and CHPC systems

Storage: Hot Water Thermal Storage and the Lithium-ion Battery



TABLE 1: TECHNOLOGIES IN PROPOSED CLUSTERS (SOURCE: JER)

generation clusters

electricity heat cold

cla

ss

ific

ati

on

clu

ste

rs

renewable energy

systems

PV solar process heat solar cooling

CSP solar thermal collectors

wind turbines solar concentrators

hydro electricity air collectors

geothermal

biomass

PVT collectors

CHP (biogas)

CHP (wood pellets/chips)

waste heat recovery

ORC heat pump thermal cooling

WHP system heat exchanger

energy efficient systems

district heating district cooling

CHP (natural gas/oil)

CHP (fuel cell)

CHPC (combined heat, power and cold)

storage

battery storage thermal (hot water) ice storage

thermal (steam)

thermal (oil)

thermal (concrete / rocks)

thermal (steel)

PCM

Moreover, an additional benchmarking for the above mentioned six pre-selected innovative

technologies (solar concentrators, PV, solar cooling, CHPC, ORC, battery storage) was

carried out based on a survey. In total, 14 feedbacks have been received from external

reviewers/international experts in different fields.

What makes this technology roadmap different and unique is its customization and

assessment to the scope of the supported call topic, the integration of renewables into

manufacturing production processes. It is also noted that road mapping is a living process

as new technologies and application areas are continuously in development. It has been

evident that the technologies scouted and assessed within are at different TRLs (Technology

Readiness Level) and typically along development lines of increasing efficiency and lowering

costs.



2. TECHNOLOGIES

2.1. RENEWABLE ENERGY SOURCES

2.1.1. HOT WATER COLLECTORS (LOW TEMPERATURE)

Responsible Authors:

Klemens Jakob: Solera, Geislingen-Binsdorf, Germany

Laura Trujillo: Solera, Geislingen-Binsdorf, Germany

Functional principle

Solar thermal collectors have the aim of using the sun radiation to convert it into heat, which

can afterwards be used, directly or indirectly with storages, for domestic hot water (DHW),

space heating, solar cooling and other applications (E.g. pool heating, process heat, etc.).

The range of temperature in which these collectors work is up to 100°C (low temperature).

Although there are other variants among this technology available, which can also reach

medium temperatures. This type of collectors, unlike the ones employed in medium and high

temperatures, don´t concentrate the sun radiation. With the exception of pool heating, which

due to the very low needed temperatures uses normally uncovered polypropylene collectors

as absorbers, there are mainly 2 types of collectors:

Flat plate collectors (Figure 1)

Due to its temperature range, normally between 50 – 80°C, they are widely used and

indicated for DHW, fan-coil or radiant floor heating, etc. Most of the sold collectors are of

this type. Advanced flat plate collectors reduce the heat losses by the implementation of a

second glazing or a special foil. These collectors can reach higher temperatures of up to

100°C.

The main components of typical flat plate collector are an outside cover (normally made of

glass), an absorber (containing a thin metallic sheet attached to a grid or coil of fluid tubing,

both recovered with black paint or metallic oxide), a thermal insulator and the collector

housing.

The outside cover reduces the convective heat losses and based on the greenhouse effect

reduces also the radiation losses of the collector. Actual collector systems additionally use

selective absorber coatings which absorb the energy intensive short wave radiation bot do

not release the long wave radiation. This reduces the radiation losses of the collectors

significantly.



FIGURE 1: WORKING PRINCIPLE OF A FLAT PLATE COLLECTOR (SOURCE: JER)

Advanced flat plate collectors further reduce the heat losses by the implementation of a

secondary glazing or a special foil between outside glazing and absorber. These collectors

can reach higher temperatures of up to 100°C. There are also evacuated flat plate collectors

but they have to be evacuated from time to time in order to maintain the vacuum, this

problem is solved with the evacuated tube collectors.

TABLE 2: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR FLAT PLATE COLLECTORS

Input Output Parameters

Solar radiation (depending on location, 950 – 1,200 kWh/m²a)

Amount of fossil fuel (for back-up auxiliary heater)

Hot water

Heating

Cooling

Aperture area: 2.26 – 2.99 m²

Peak output: 1,706 – 2,114 W

Surface: 2 – 38 m²

Power: 1,448 – 24,772 kWh/year

Evacuated tube collectors (Figure 2)

Evacuated tube collectors work within a temperature range above 70°C. They achieve

higher efficiencies in transitions periods and in winter when compared with flat collectors.

This fact is important if the collectors have to cover the entire heat demand or at least a

great part of it during the year [8].

The working principle of these collectors is also the greenhouse effect, but in this case no

thermal isolator is needed because the vacuum almost eliminates the convective thermal



losses to the glass exterior. To further reduce the radiation losses, the absorber area of

these collectors are also coated with a selective coating, which absorbs the energy intensive

short wave radiation and significantly reduces the release of long wave irradiation.

These collectors are composed of a glass tubes group in which interior the vacuum has

been made. Inside each tube there is a heat pipe and a metal sheet that absorbs the

radiation and transfer the heat to the fluid circulating through the pipe.

FIGURE 2: WORKING PRINCIPLE OF EVACUATED TUBE COLLECTOR (SOURCE: JER)



TABLE 3: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR EVACUATED TUBE COLLECTORS


Solar radiation (depending on location, 950 – 2,500 kWh/m²a


Hot water

Heating

Cooling

Aperture area: 0.94 – 2.83 m²

Peak output: 650 – 1,944 W

The price for the installation in terms of generated heat for low temperature collectors varies

from 3 – 19 Cent/kWh (for DHW, district heating or process heat applications) or 14 – 23

Cent/kWh (for Combi systems with DHW + space heating in buildings) [8].

There are different ways of classifying these solar systems. Considering how the thermal

transfer is realized there are two options:

Open circuit or direct transfer: the fluid, which runs through the collectors directly,

goes into the storage. No heat exchanger is needed in-between.

Closed circuit or indirect transfer (closed loop): there are two different circuits one for

the collector (water glycol) and one for the storage (water). The heat collected by the

collectors is transferred by a heat exchanger from one circuit to the other.

Considering how the thermal fluid circulates, there are two options:

Natural circulation or thermosyphon (passive): the difference of temperature (and

density) between the storage and the collectors produces a natural circulation without

needing a pump. The storage´s location must be always above the collector´s.

Forced circulation (active): A pump circulates the thermal fluid.

Each system has its advantages and disadvantages and it is recommended for certain

applications (e.g. natural circuit with open circuit for a small isolated house, forced circulation

with closed circuit for an apartment house).

FIGURE 3: SYSTEM SCHEME OF A TYPICAL SOLAR COLLECTOR SYSTEM (SOURCE: SOLERA)



SWOT Analysis for low temperature collectors

TABLE 4: SWOT ANALYSIS FOR LOW TEMERATURE COLLECTORS – TECHNICAL ASPECTS

SWOT TECHNICAL ASPECTS

ST

RE

NG

HT

S

Compatibility with conventional heating systems

Compatibility with other renewable energy systems

Tracking not required

Very modular systems

Use of direct and diffuse radiation, high solar yields possible

Heat exchanger is needed

Back-up system is normally needed when water is used the whole year

Less efficient at higher temperature differentials

Storage is normally required

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S

Locations with good solar irradiation

Isolated buildings / regions

Future building integration

Standardization

Improvement of manufacturing technologies

Competing technologies

Already installed conventional systems in existing buildings (non-worthy replacement)

TH

RE

AT

S

TABLE 5: SWOT ANALYSIS FOR LOW TEMERATURE COLLECTORS – COSTS, MARKETING AND ECOLOGY

SWOT COSTS, MARKETING AND ECOLOGY

ST

RE

NG

HT

S

Cost related parameters

Low specific collector prices

(Flat plate 180 – 240 €/m2)

(Vacuum tube 500 – 600 €/m2)

Marketing aspects

Positive environmental profile – mitigation of CO2 emissions

State of art equipment / system

Commercially available


Incentives required for short payback times

Marketing aspects

Not enough existing installations at an industrial level in Europe

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S


Increase in fossil fuel prices

Financial incentives

Available financial incentives per country

Prospects for financial incentives (current preparation – discussion on upcoming legislation)

Market related parameters

Opening of jobs, businesses, companies

New geographic markets emerging outside the EU

“Pioneers” and “front runners” both in green technology and environment protection are looking to invest and buy new


Volatile input material costs

Decrease in fossil fuel prices


None financial incentives or reduction of the existing financial incentives, ceasing the technology being attractive (E.g. Spain)

Financial incentives for other type of technologies (E.g. Spain)

Legislation of the country supporting fossil fuels technologies (E.g. Spain)


End user’s behaviour relates with system’s performance

TH

RE

AT

S



2.1.2. SOLAR CONCENTRATORS (MEDIUM TEMPERATURE)





Movable concentrating collectors mainly use the direct radiation of the sun. By concentrating

the sunlight, high energy density – and therefore high temperatures can be reached.

However, to ensure a concentration on the absorber, they typically need to be tracked

normal to the position of the sun (1-axis tracking), which increases the technical effort for

these systems. For higher concentrating systems there are mainly two different technologies

on the market, liner concentrating parabolic trough and Fresnel collectors. Parabolic trough

collectors consist of a linear absorber tube and a parabolic shaped mirror (concentrator),

which is creating a focal line along the absorber tube. Large parabolic trough collectors with

concentration factors of 40 – 80 easily reach temperatures of 300°C and above and are

widely used for electricity generation in e.g. large solar parks (e.g. Andasol I, II and III).

Medium to small scale parabolic trough collectors reach concentration factors between 10

and 80 and can deliver temperatures usable for solar process heat between 100°C and

400°C. These technologies are used for industrial processes, which require temperatures in

most cases provided as process steam. The big advantage is that the generated process

steam can be quite easily integrated into existing steam networks supplying steam to the

different processes.

To generate the steam either indirect systems with thermal oil as heat transfer medium in

the collector circuit and a thermal oil driven steam generator or pressurised water as heat

transfer medium with a pressurised hot water storage and a water to steam generator are

used. Some new cost optimised developments are also addressing a direct steam

generation in the collector circuit.

The advantage of using thermal oil in the collector circuit is the low system pressure. On the

other hand, the thermal oil is quite costly and some of them are toxic. In case of the

pressurised water and the direct steam generation the whole collector circuit needs to be

considered as pressurised equipment and therefore needs to full fill special standards and

regulations.

Parabolic trough collectors

Parabolic trough collectors concentrate the direct solar radiation onto an absorber tube, by

means of a reflective surface (mirror), in order to produce medium temperatures in the heat

transfer fluid that flows along it, which can be water or thermal oil, depending on the final

required temperature.

The demineralized water or a mixture of an antifreeze (e.g. ethylene glycol, propylene glycol,

etc.) can be used in case of lower temperatures (< 120°C). For higher temperatures either

a synthetic thermal oil or demineralized water (pressurised or direct steam generation) is

used. For the pressurised water and for the direct steam generation special measures for

frost protection are required.



FIGURE 4: FUNCTIONAL PRINCIPLE OF PARABOLIC TROUGH COLLECTORS (SOURCE: SOLERA)

Concentrating collectors can only use the direct solar irradiation, and due to that, have a

tracking system in order to modify the mirror position and concentrate the maximum direct

solar radiation throughout the day. Parabolic trough collectors are normally north-south

oriented and track from east to west.

The total efficiency of the collector depends on multiple factors, as the ones involved in the

optical and thermal efficiency.

TABLE 6: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR PARABOLIC TROUGH COLLECTORS


Solar radiation

Amount of fossil fuel

(for back-up auxiliary heater)

Pressurised hot water or Steam

Surface: 3.4 m² / collector

Power: 1.7 kWth/ collector

Optical efficiency: 75%

Linear Fresnel collectors

The Fresnel collector has multiple slightly curved reflective surfaces (almost flat) forming a

mirror field (reflector) that concentrates the direct radiation onto an absorber tube that is

fixed in space above the reflector. It also has the capacity of tracking the sun in a single axle

thanks to the rotation of the reflective surfaces.

The absorber tube is fixed and the reflectors of the mirror field rotate. Due to the distance

between absorber tube and reflectors some radiation is lost and does not reach the absorber

tube. In order to reflect some of this initially lost radiation there is a secondary CPC

concentrator behind the absorber tube.



FIGURE 5: FUNCTIONAL PRINCIPLE OF LINEAR FRESNEL COLLECTORS (SOURCE: JER)

The current Fresnel collectors are defined to have a lower optical efficiency and therefore

reach for the same collector aperture area smaller annual yields when compared with

parabolic collectors. The advantage of linear Fresnel collectors is the low wind load, which

is important for installations on the roof of production halls.

TABLE 7: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR LINEAR FRESNEL COLLECTORS


Solar radiation

Amount of fossil fuel

(for back-up auxiliary heater)

Pressurised hot water or steam






SWOT Analysis of concentrating collector systems for industrial applications

(medium temperatures)

TABLE 8: SWOT ANALYSIS FOR TRACKED CONCENTRATING COLLECTORS FOR MEDIUM TEMPERATURES

– TECHNICAL ASPECTS


ST

RE

NG

HT

S


High efficiency at high working temperatures


Tracked concentrators allow efficient use of direct solar radiation


Storage implementation (thermal oil or pressurized water) is possible and

increases the energy yield and availability

Storage is required for continuous heat supply especially on partly clouded days

Large unoccupied area (roof or field) required

No use of indirect irradiation → high direct irradiation fraction is required

Normally works as a secondary system

Surface´s elevation can be a problem or project limitation

Transferred temperature limitation due to the existing oils

Higher costs of materials

Exposure to wind (wind loads) to take into account when planning

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S

Locations with high direct solar irradiation

Isolated buildings / regions / islands with high energy costs


Standardization


Competing technologies’ capability of covering peak demand


Industries already built with not enough space available in its surroundings or too much inclined roofs (e.g. Spain)

TH

RE

AT

S



TABLE 9: SWOT ANALYSIS FOR TRACKED CONCENTRATING COLLECTORS FOR MEDIUM TEMPERATURES

– COSTS, MARKETING AND ECOLOGOY


ST

RE

NG

HT

S


Independent of energy markets

Marketing and Ecology aspects





High storage costs in case of thermal oil

Marketing aspects

Pressurised system requires special trained personal

Non-adequately trained technical personnel

Lack of automated features

Not enough existing installations at an industrial level

Existing doubts concerning its viability among industrials

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S





Proposal for green tax package









None financial incentives or reduction of the existing financial incentives, ceasing the technology being attractive (E.g. Spain)

Financial incentives for other type of technologies (e.g. Spain)

Legislation of the country supporting fossil fuels technologies (e.g. Spain)



TH

RE

AT

S



2.1.3. AIR COLLECTORS



Samuel Baumeister: JER, Weinstadt, Germany


Solar air collectors are thermal collectors, which use air for heat transport to heat up (pre

heat) outside air. Systems for air pre-heating are used / installed in buildings for warming up

fresh air without waste heat recovery systems. Solar air collectors are mainly differentiated

by the absorber deposition / barrier as well as the way air is lead along the absorbers.

Simple and cost saving air collectors for pre-heating outside air work without a transparent

barrier and suck in the air through thin perforate absorber plate / metal. The trapeze metal

construction of the absorber metal serves also as weather-proof of the building. The

transparently covered absorber systems lead the air either between cover / barrier and

absorber or - for better thermal quality – under the absorber sheet metal (called undercurrent

absorber).

As with water collectors, wastage of heat from absorber is dependent on the access

cover / barrier system:

Unglazed cover absorber used for systems with less temperature increase / raise.

Air collectors with queuing air between absorber and cover / barrier cause less heat

loss and are therefore more appropriate for higher temperatures.

Due to the remarkably lower efficiency of heat transport from absorber to air, most collector

systems use absorber (cooling) ribs to increase the heat transfer area.

In regards to the production and cost for the type of rips are the flat kept / hold rips are easier

to produce and less costly.

FIGURE 6: FUNCTIONAL PRINCIPLE OF AIRCOLLECTORS (SOURCE: GRAMMER SOLAR GMBH)



TABLE 10: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR AIR COLLECTORS


Inlet air temperature

Ambient temperature

Outlet air temperature

Hot air temperature

Flat plate air collector 70 – 100°C

Vacuum air tube till 120°C




SWOT Analysis of air collector systems for industrial applications

TABLE 11: SWOT ANALYSIS FOR AIR COLLECTORS – TECHNICAL ASPECTS


ST

RE

NG

HT

S No antifreeze and overheating problems

Simple security and systems engineering

Fast reaction rate in the exchange of thermal energy

Still useable by low solar radiation


Low outlet temperatures

Not very effective storage options

Additional heat exchanger needed

Large size of air pipes

Large space for collectors required

Additional air shaft necessary WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S


Standardization

Still useable in low irradiation locations

Already installed conventional air handling systems in existing buildings (non-worthy replacement)

TH

RE

AT

S

TABLE 12: SWOT ANALYSIS FOR AIR COLLECTORS – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S



Relatively low maintenance cost

Low capital cost

Marketing and Ecology aspects


Good integration possibility into a building envelope



Incentives required for short payback times

Marketing aspects

Not enough existing installations at an industrial level in Europe

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S






“Pioneers” and “front runners” both in green technology and environment protection are looking to invest




None financial incentives or reduction of the existing financial incentives, ceasing the technology being attractive



TH

RE

AT

S



2.1.4. SOLAR PROCESS HEAT




Dr. Marco Cozzini: EURAC, Bolzano, Italy

Industrial processes are responsible for a high amount of energy in a temperature range up

to 250°C. Solar process heat is defined as a system, which use the solar heat for these

industrial processes instead of domestic hot water or space heating in the building.

According to the process temperatures different solar collector types can be used to heat up

the process fluid. This temperature level is also responsible for the decision to use a heat

exchanger and also for the medium of the heat ransfer fluid. Typically, storage is the link

between the solar collector field and the process. Due to the fact that an industry requires a

lot of heat, large volumes of the storages are needed.

Currently solar thermal systems are still mainly used in the fields of domestic hot water

generation and supporting space-heating systems in residential buildings. Meanwhile these

systems are nearly state of the art and widespread in the building sector.

FIGURE 7: PRINCIPLE OF A SOLAR PROCESS HEAT SYSTEM (SOURCE: JER)

In Europe, the final energy consumption of the industrial and commercial sector is about

28% of the over all energy consumption and 2/3 of this energy is consumed for heating

applications [2]. However, in the industrial and commercial sector, the active use of solar

heat is still not very common. The potential analysis for solar heat in industrial processes

within Task 33 of the IEA Solar Heating and Cooling Programme showed that in most

industrial processes low and medium temperature is needed. More than 60% of the industry

uses process heat with temperatures below 250°C. The most suitable branches are in the

food and drink-, textile-, pulp and paper- and Transport equipment industry [3].



For solar process heat applications different collector types are used and available on the

market. The temperature range of the process decides whether concentrating or non-

concentrating collectors are required. Movable concentrating collectors mainly use the direct

radiation of the sun. By concentrating the sunlight, high energy density – and therefore high

temperatures (up to 450°C) can be reached. However, to ensure a concentration on the

absorber, they typically need to be tracked normal to the position of the sun (1-axis tracking),

which increases the technical effort for these systems.

The use of solar thermal energy for industrial processes has a wide range of applications.

The most significant applications at low to medium temperature level are in the fields of food

beverage and textile industries [5]. As Table 13 shows most of the industrial sectors need

heat in the range of 40 – 110°C for heating up and boiling water for different processes. The

advanced flat plate collector and the evacuated tube collector are appropriate for most of

these processes, because they are very efficient in this temperature range [6]. While high

temperature collectors, like the Fresnel and Parabolic through collector, were mainly used

for processes in the chemical industry.

TABLE 13 INDUSTRIAL SECTORS AND PROCESSES WITH ITS TEMPERATURE LEVEL [4]

Industrial sector

Process Temperature level [°C]

Appropriate collector technology

Food and beverages

- drying

- washing

- pasteurising

- boiling

- heat treatment

- sterilising

30 – 90

40 – 80

80 – 110

95 – 105

40 – 60

140 – 150

Air / flat plate collector

Flat plate collector

Evacuated tube collector

Evacuated tube collector


CPC, evacuated tube collector

Textile industry

- washing

- bleaching

- dyeing

40 – 80

60 – 100

100 – 160



CPC, evacuated tube collector

Chemical industry

- boiling

- distilling

- various chemical processes

95 – 105

110 – 300

120 - 180

Evacuated tube collector Fresnel / Parabolic through collector

Fresnel / Parabolic through collector

All sectors - pre heating of boiler feed water

- heating of production halls

30 – 100

30 – 80



The following figures are based on data provided by AEE INTEC and shows the worldwide

installed solar thermal plants for process heat with a total installed capacity of approximately

100 MWth.

Following Figure 8 shows different industry sectors and the installed plants therefore. The

mining sector with the highest capacity of roundabout 27 MWth is also the sector with less

plants. That means that there are very large operating plants which indicates the mining

projects in the desert of Chile. Main sectors for solar process heat are currently as mentioned

the mining sector but also food and textile companies.



FIGURE 8: SOLAR INDUSTRIAL PROCESS HEAT PLANTS – DISTRIBUTION BY INDUSTRY SECTOR (SOURCE: JER;

DATABASE: AEE INTEC)

FIGURE 9: SOLAR INDUSTRIAL PROCESS HEAT PLANTS – DISTRIBUTION BY COUNTRY (SOURCE: JER;

DATABASE: AEE INTEC)

The analysis of 155 installed solar process heat systems worldwide shows in Figure 10 that

75 of these plants have used flat plate collectors and only about 18 systems were realised

with concentrating collectors (CPC and parabolic trough). Furthermore, the investigation of



the size of the collector fields shows that the most plants are in a range between 300 – 1,000

m2. Operating solar process heat plants till 1,000 m2 represent an amount of approximately

90% as showed in Figure 11.

FIGURE 10: COLLECTOR TYPE OF INSTALLED SOLAR PROCESS HEAT SYSTEMS (SOURCE: JER; DATABASE: AEE INTEC)

FIGURE 11: COLLECTOR SIZE OF INSTALLED SOLAR PROCESS HEAT SYSTEMS (SOURCE: JER; DATABASE: AEE INTEC)



Solar thermal systems have the potential to provide renewable industrial process heat.

When correctly integrated within an industrial process, they can provide significant progress

towards both increased energy efficiency and reduction in emissions [7].

Energetic and economic performance

The potential of solar industrial installations is in the economy scale, which can be achieved

in comparison to other applications. The consequence is that low cost systems are

achievable both for components and installation, so that solar systems for industrial process

heat production can become economically competitive to fossil fuels on a short term.

Present investment costs for solar thermal systems range from 600 to 800 EUR/m2

(corresponding to 420 – 560 EUR/kW of thermal power) leading to average energy costs in

Southern Europe from 4 to 6 Cent/kWh for very low temperature applications and from 9 to

15 Cent/kWh for medium temperature systems.

The energetic performance factors of the different collector types (low and medium

temperature as well as air collectors) are described and can be found in the next different

sub-chapters.

Integration possibilities

Different temperature levels can be achieved by solar thermal collectors with different heat

transfer mediums (e.g. hot water, steam, air, etc.) to provide industrial heat for

manufacturing processes. Solar thermal collectors can be installed either on factory roofs

and facades or besides on the ground. The main challenge for the use of solar thermal

collectors at factories is that often no additional weight / loads can be installed on the roofs.

For the integration of the solar thermal system into the existing process heat system it is

recommended to install thermal energy storage (Chapter 2.2.1) due to the fluctuation of the

solar energy output by changing weather conditions.



2.1.5. SOLAR COOLING





Solar thermal cooling technology is using solar energy as energy source to run an air-

conditioning system, which is a combination of thermally driven heat pumps / chillers with

solar thermal collectors (Chapter 2.1.4). Instead of conventional electricity driven

compression chillers sorption chillers are using environmentally friendly refrigerants (water

or ammonia) and they have a very low electricity demand for the chiller itself. A more detailed

description of sorption chillers can be found in Chapter 2.3.2. Solar cooling systems either

produce chilled water (so-called closed systems using absorption or adsorption chillers) or

conditioned air (so-called open systems, DEC or liquid sorption systems). Nevertheless,

maximum operation time and low-cost driving heat for sorption chillers are the key for

economic efficiency of solar thermal cooling systems. Solar cooling systems can be

characterized by the electrical Coefficient Of Performance (COP) of the system (COPel.),

which is the ratio of the electricity consumption of the complete system divided by the

supplied cooling capacity of the system. Such COPel. for solar thermal cooling systems are

usually between 6 and 15 depending on the used chiller and heat rejection technology as

well as the location (e.g. hot and wet climate or moderate climate). Two further parameters

are the thermal COPth. of the chiller as well as the solar fraction (f) of the system itself, which

are describing the performance of the chiller and the amount of energy provided by the solar

thermal technology divided by the total energy required to run the system, respectively [9].

FIGURE 12: SYSTEM SCHEME OF A SOLAR COOLING SYSTEM – CLOSED SYSTEM (SOURCE: JER)



Integration possibilieties

As solar cooling systems are supplying either chilled water at 6 – 19°C (depending on cold

distribution system, e.g. fan coils or ceilings panels) or conditioned air at 16 – 20°C these

systems can be easily integrated in conventional air-conditioning systems to substitute a

part of the required cooling capacity for the manufacturing processes or the buildings [9].

The main challenge for the integration of solar cooling systems is again the required space

for the solar thermal collectors as heat source at the factory side similar to the solar process

heat application (Chapter 2.1.1).

Energetic and Economic performance

TABLE 14: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR SOLAR COOLING SYSTEMS


Solar radiation


Closed cold water systems:

Chilled water outlet temperature

Chilled water inlet temperature

(coming from the building / process)

Open air systems:

Supply air temperature

Return air temperature

(coming from the building)

COPth (0.6 – 1.8 depending on the sorption technology)

COPel (6 – 15)

Solar fraction > 70%

SWOT Analysis of solar cooling systems for industrial applications

TABLE 15: SWOT ANALYSIS OF SOLAR COOLING SYSTEMS – TECHNICAL ASPECTS


ST

RE

NG

HT

S

High electrical COP and high potential for further increase of solar cooling system’s efficiency

Compatibility with conventional heating / cooling & existing distribution systems

Extension of the use of existing solar thermal systems

Best configurations result in high performance operation

Tailor-made systems achieving better performance

Less losses of transformation from primary energy to electricity

Storage required

Large unoccupied area required

An auxiliary system required

Not efficient for all different combinations of location / application

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S

Locations with good solar irradiation – high cooling loads – high fuel prices



Standardization


Competing technologies capability of covering peak demand


PV driven compression chillers

TH

RE

AT

S



TABLE 16: SWOT ANALYSIS OF SOLAR COOLING SYSTEMS – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S


Relatively low operating cost (in off-gas mode: e.g. cooling)

Almost independent of energy markets

Marketing aspects

Relatively good cost of primary energy saved



Existing installation as best practices


High capital cost

Relatively high installation and transportation cost

Relatively high maintenance cost

Marketing aspects

Limited market applications

Lack of user friendly interface and automated features


WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S


Increase in fuel prices

Cheaper than electric-driven compression chillers










Volatile input material costs (e.g. copper)


Lack of awareness for the wider public


TH

RE

AT

S



2.1.6. PHOTOVOLTAIK





The photovoltaic (PV) technology consists in using the solar energy as an energy source in

order to generate electricity thanks to the photovoltaic effect, which is the working principle

of this technology.

The PV effect of the PV solar cells consists of two different (or differently doped) semi-

conducting materials (E.g. silicon, germanium) in close contact each other, that generate an

electrical current when exposed to sunlight. Sunlight provides electrons with the energy to

move cross the junction between the two materials more easily in one direction than in the

other. This gives one side of the junction a negative charge with respect to the other side

(e.g. p-n junction) and generates a voltage and a direct current (DC) [10]).

The basic installation needed for the abovementioned purpose has:

PV panels: formed by the solar cells, are the ones that generate the DC power from

the solar energy.

Inverters: to turn the DC power into alternating current (AC) power (230 V) compatible

with the grid.

Solar power meters: to measure the electricity generated by the plant

Monitoring system: a device to control the installation


The installations can be connected to the electricity network (“on grid systems” where all the

electricity is delivered to the grid or just one part, and the rest is consumed. A battery is

normally not needed) or not connected to the electricity network (“off grid systems” where

all the generated energy is used to meet the electricity consumption in the same place where

the demand is produced. A battery is normally needed).



FIGURE 13: SYSTEM SCHEME OF A PHOTOVOLTAIC SYSTEM (SOURCE: SOLERA)


TABLE 17: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR PHOTOVOLTAIK MODULES


Solar radiation Electricity Surface: 6 – 8 m²; 10 – 15 m²

Power: 1 kWpeak

SWOT Analysis of photovoltaik systems for industrial applications

TABLE 18: SWOT ANALYSIS FOR PHOTOVOLTAIK MODULES – TECHNICAL ASPECTS


ST

RE

NG

HT

S

Compatibility with conventional electricity producer systems



Storage not always required but enables to increase the output of the installation

Large area not needed

Auxiliary system not always required

Long service life

High technological level of devices and companies

Easy to install and dismantle

PV panels have no mechanically moving parts → far less breakages, less maintenance

Relatively low maintenance

Proven reliability

Effective solution to energy demand peaks – especially in hot summer months

Material dependency (E.g. Silicon)

Low or null production and conversion efficiency with bad weather conditions

Inverter is required

Energy losses during DC / AC conversion

WE

AK

NE

SS

ES



SWOT TECHNICAL ASPECTS O

PP

OR

TU

NIT

IES

Locations with good solar irradiation – high fuel prices


Standardization


The efficiency of the system depends on the ground properties (typically not a dramatic effect, however).

In climates where only heating or cooling is needed, the local ground temperature can be changed in a non-negligible way after several years of operation, reducing efficiency (however, simulations and experimental surveys have shown that this is also not a dramatic effect if proper sizing is done).

Improper coupling with the associated conditioning system (e.g., poor heat exchanger sizing).

Concern about the use of water-glycol mixtures (though propylene glycol is anyway non-toxic).

TH

RE

AT

S

TABLE 19: SWOT ANALYSIS FOR PHOTOVOLTAIK MODULES – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S


Relatively low operating and maintenance cost

Almost independent of energy markets

Marketing aspects




Many market applications are available (E.g. carports, facades, etc.)

Increase in energy independence

Make no noise that can disturb people in surroundings


Relatively low installation and transportation cost

Relatively low maintenance cost.

Time costs due to large and complex administrative procedures

Storage batteries increase the investment cost

Marketing aspects


WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S



Cheaper than other renewable technologies available for producing electricity





Possible sale of the surplus energy





Good public acceptance and support


Increasing performances of building envelopes (lowering heating demand and making it difficult to recover the high installation costs).


Increasing of incentives for other technologies.


Scarce diffusion of information about this technology, at least compared to other RES.

Increasing performances and/or price lowering of air-air heat pumps (where economies of scale can be applied more easily).

TH

RE

AT

S



2.1.7. PHOTOVOLTAIC-THERMAL COLLECTORS





Photovoltaic-Thermal (PVT) collectors are combined modules, which uses sun energy to

produce electricity and heat energy. PVT consists of Photovoltaic modules on the topside

and solar flat collectors on the bottom side. There are so called ‘covered modules’ with high

efficient solar heat production and ‘uncovered modules’, which more concentrate on PV-

electricity production. Different type of modules with regards to the medium, on one site

water heated up, thermal collectors, on the other site air heated up, like air collectors. Last

one does not qualified for plants and factories, as they produce low temperature and difficult

to store. PVT collector may be used in different ways / options, once to use the heat

produced as well as for night emanation against the sky to cool down the medium.

Nevertheless, this needs a large storage option. The problem of the combined collectors is

that both users may interfere each other in the effectiveness. The solar cells are most

effective at low temperatures. Benefits decrease when temperature increases. Design and

size of a Hybrid system must consider that on one site the PV-value / benefit increase as

much as the modules are cooled down but on the other site a more effective solar thermal

system reaches higher temperatures and suites a broader number of production processes.

The aim is a compromise, which will produce most effective result for both users.

Under the subject “combination usage” (PVT) many research and development is ongoing.

Nevertheless, some products and brands are already on the market.

FIGURE 14: STRUCTURE OF PVT COLLECTORS (SOURCE: SOLIMPEKS)


The installations can be connected to the electricity network (“on grid systems” where all the

electricity is delivered to the grid or just one part, and the rest is consumed. A battery is

normally not needed) or not connected to the electricity network (“off grid systems” where

all the generated energy is used to meet the electricity consumption in the same place where



the demand is produced. A battery is normally needed). Additional thermal heat can be

supplied by the PVT collector to any manufacturing process which needs temperatures of

about 40 – 70°C.


TABLE 20: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR PHOTOVOLTAIK THERMAL COLLECTORS


Solar radiation Electricity

Hot water

Surface: 2 m²

Power: 0.25 kWpeak electricity

1.7 kWth / collector

SWOT Analysis of photovoltaik thermal collectores for industrial application

TABLE 21: SWOT ANALYSIS FOR PHOTOVOLTAIK THERMAL SYSTEMS – TECHNICAL ASPECTS


ST

RE

NG

HT

S High efficiency by the same size of space

Far less floor space (e.g. Roof space) needed compared to separate systems

By small space still electricity and heat production possible

Low maintenance

Storage required

Fairly new and still under development

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S

High potential for further increase of PVT collector’s efficiency



Standardization


Already installed conventional systems might be reviewed if exchange is worth wile

TH

RE

AT

S

TABLE 22: SWOT ANALYSIS FOR PHOTOVOLTAIK THERMAL SYSTEMS – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S


Less installation and time costs

Relatively low maintenance cost

Marketing aspects

Higher gain on energy by using the cooling effect of the Solar cells

Significantly improved return on investment by combining

Uniformed visual optic


Relatively high capital cost

Marketing aspects

Few manufacturers and vendors


WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S



Further research will reduce cost






TH

RE

AT

S



2.1.8. CONCENTRATED SOLAR POWER (CSP)





Hereafter, concentrated solar power technologies for the generation of electricity similar to

those from Chapter 2.1.2 (parabolic trough collectors and linear fresnel collectors, see also

Figure 15) are described.

FIGURE 15: PRINCIPLE SOLAR CONCENTRATION SYSTEMS – ABSORBER TUBE (SOURCE: JER)

The working principle is the concentration of the direct solar radiation onto an absorber tube,

in which a heat transfer fluid is pumped through, operating both technologies at its highest

temperatures but in this case, with the aim of obtaining steam to feed a power cycle and

generate electricity.

There are mainly two possibilities of steam generation:

Indirect: Is the most common one. Operates in a pressurised circuit where the heat

transfer fluid does not evaporate in the collector field and uses additional devices,

heat exchangers, to generate superheated steam that will be converted in electrical

energy by a group of turbines connected to an alternator in a conventional steam

cycle or a combined steam and gas cycle.

Direct: Not so common and commercially developed. Generates steam with high

pressure and temperature, without the use of thermal oil and heat exchangers.

Operating with high pressures and temperatures makes the system control more

difficult.



Regarding the thermodynamic power cycle possibilities for CSP, the possible alternatives

are de Brayton and the Stirling cycle.

There are two other technologies of concentrated solar power in order to generate electricity:

the parabolic dish and the central receiver systems also known as solar power tower (Figure

16). These two technologies have two tracking axles, use direct and diffuse radiation,

concentrating it in a point (not in an absorber tube line) and reach higher temperatures

(> 450°C und up to 1,000°C).

In a parabolic dish, normally called Stirling dish because of the abovementioned used cycle,

the solar radiation is concentrated by a dish collector into a point located in the front part of

it. On the other hand, the central receiver system or solar power tower is characterized by a

heliostat group that concentrate the radiation into a receiver located in the upper side of a

tower.

FIGURE 16: PRINCIPLE OF SOLAR CONCENTRATION SYSTEMS – CENTRAL RECEIVER (SOURCE: JER)


CSP systems need large areas to produce e.g. 1 MW of electricity. Therefore, the required

ground areas are about 12,500 m2 (Fresnel collector), 20,000 m2 (parabolic trough) and

40,000 m2 (central receiver tower), respectively. The installations can be connected to the

electricity network (“on grid systems” where all the electricity is delivered to the grid or just

one part, and the rest is consumed on site. Sometimes thermal energy storage makes sense

to store heat for the nigh time electricity production.



FIGURE 17: BASIC ELECTRICITY PRODUCTION SCHEME WITH PARABOLIC COLLECTORS (SOURCE: SOLERA)

FIGURE 18: BASIC ELECTRICITY PRODUCTION SCHEME WITH LINEAR FRESNEL COLLECTORS (SOURCE: SOLERA)




Due to the high investment costs at present neither the parabolic dish nor the central receiver

systems should be considered for industrial applications.

TABLE 23: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR PARABOLIC TROUGH- AND FRESNEL COLLECTORS


Solar radiation Electricity Surface: 3,4 m² / collector

Power: 1,7 kWth / collector

SWOT Analysis of concentrated solar power systems for industrial applications

TABLE 24: SWOT ANALYSIS OF CONCENTRATED SOLAR POWER SYSTEMS – TECHNICAL ASPECTS


ST

RE

NG

HT

S


Best configurations result in high performance operation. High efficiency at high working temperatures


Tracking the sun allows to concentrate more direct radiation


Storage is possible and increase the feasible output

Higher optical efficiency and annual yield

Storage is normally required. The thermal capacity of the storage is limited

Large unoccupied area required

Use direct irradiation.

Cloudy or dusty skies reduce the direct solar radiation and thereby the performance and yield of the system

Normally works as a secondary system

Surface´s elevation can be a problem or project´s limitation

Transferred temperature limitation due to the existing oils

Exposure to wind (wind loads) to take into account when planning

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S




Standardization




Industries already built with not enough space available in its surroundings or too much inclined roofs (e.g. Spain)

TH

RE

AT

S



TABLE 25: SWOT ANALYSIS OF CONCENTRATED SOLAR POWER SYSTEMS – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S



Marketing aspects



Commercially available.

Installations available despite they are not directly for industrial purpose



High storage costs

Variable maintenance costs depending on the location conditions

Marketing aspects


Lack of automated features



WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S
















None financial incentives or reduction of the existing financial incentives, ceasing the technology being attractive (e.g. Spain)


Legislation of the country supporting fossil fuels technologies (e.g. Spain)

Regulatory uncertainty (e.g. Spain)




TH

RE

AT

S



2.1.9. WIND TURBINES


Dr. Rick Greenough DMU, Leicester, United Kingdom

Dr. Andy Wright: DMU, Leicester, United Kingdom


Most modern wind turbines convert the kinetic energy in a moving mass of air into electrical

energy that can be used locally or fed into the electricity grid to generate revenue. Wind

power is one of the oldest forms of renewable energy, and was originally used to do

mechanical work directly for example grinding corn or lifting water. In remote locations, wind

power is still used in this way today, but it is much more common to use wind turbines to

generate electrical energy. The two basic designs are horizontal axis wind turbines (HAWT)

and vertical axis (VAWT). These are illustrated below for comparison.

FIGURE 19: HAWT AND VAWT SCHEMES (SOURCE: JER)

The latter have the advantage that the nacelle does not need to be turned to face the wind,

but the former are capable of much higher power outputs. When used for water pumping,

turbines are usually multi-bladed HAWT designs with relatively low efficiency and high

torque. When used for power generation, turbines are usually HAWT designs with three (or



sometimes two) high aspect ratio blades. Older simpler turbines may rotate at fixed speeds

related to grid frequency by a gearbox and the number of poles in the induction generator,

with the power maximised by pitching the blades to match wind speed. Newer variable

speed designs use power electronics to allow the turbine to remain efficient over a wider

range of wind speeds, while still controlling blade pitch. Some turbines such as the Enercon

range use power electronics and multipole power converters to eliminate the gearbox, in the

interests of reliability.

Smaller turbines (i.e. up to 10 kW) do not generate the revenue that would justify complex

blade pitching or nacelle steering systems. They therefore tend to be inherently less efficient

than larger designs that are capable of efficient operation over a wider range of wind speeds.

However, small turbines are ideal for direct integration with electrical loads in remote

locations. Since their control systems are relatively simple, small turbines usually feature a

simple furling mechanism to avoid damage in high wind speeds by turning the rotor out of

the wind. An example of an advanced small wind turbine that features blade pitching, an

emergency braking system and passive yawing is the 5 kW Evance R9000 which has a 5.5

m diameter rotor.

FIGURE 20: CONSTRUCTION OF WIND TURBINE (SOURCE: ALSTOM)

For any given wind speed, power output scales with the square of the rotor diameter, so

turbine manufacturers focus much development effort on the construction of ever larger

turbines. At the time of writing, the latest devices are rated at 7 MW (the Enercon E-126,

with a diameter of 126 m) or 8 MW (the Vestas V164, with a diameter of 164 m). Wind

turbines do not suit any particular industrial process more than any other. They should be



regarded as a source of renewable electrical energy and/or a source of revenue when

supplying the grid.

The most important factors in determining viability of wind generation are usually amount of

wind on site, and acceptability for planning and local community.


The power generated is a function of the density of the air, the swept area of the rotor and

the cube of the wind speed. Wind speed increases with hub height and is affected by

topography and ‘roughness’ of the land nearby. For this reason, a turbine in the open country

will generate more energy than the same device in an urban location, such as an industrial

estate. However, since the cost of grid integration depends on the availability of a suitable

connection point and the local strength of the grid, industrial areas may have an advantage

over more remote locations where grid connection is more expensive. It is common to see

medium-sized wind turbines used in farms and other agricultural facilities where wind

conditions are favourable, local objections are few and there is already a suitable three

phase grid connection.


The power extracted from the wind is limited by the aerodynamic efficiency of the blades,

the electrical efficiency of the generator and a fundamental physical limit known as the Betz

limit. Another significant limit on the energy delivered over time is the variability of the wind

speed. Wind that is below the cut-in speed will not cause the turbine to rotate and wind

speeds above the cut-out speed will cause the turbine to shut down for safety reasons. For

this reason, the ratio of the average power output and the rated power (the capacity factor)

is typically only 35% for an onshore turbine.

TABLE 26: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR WIND TURBINES


Kinetic energy in wind Kinetic energy in rotating shaft (e.g. when used for pumping) or much more commonly

Electrical energy

Capacity factor

Rated power

Cut-in wind speed

Cut-out wind speed



SWOT Analysis of wind turbine systems for industrial applications

TABLE 27: SWOT ANALYSIS OF WIND TURBINE SYSTEMS – TECHNICAL ASPECTS


ST

RE

NG

HT

S

Relatively simple, mature technology

Compatibility with any electrical load

Excess capacity can be used for revenue generation

Likely energy capture can be estimated accurately from anemometer survey and weather station data

In some locations, wind speed is strongly inversely correlated with insolation, so wind power may complement a PV installation well

Many sites unsuitable for wind generation, e.g. urban or in valleys.

Intermittency

Less efficient when sited near buildings

Local grid connection may need strengthening for feed-in to distribution network

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S

Locations with good existing grid connections, high average wind speeds, good topography (e.g. on a ridge to benefit from wind speed up) and low surface roughness


Industrial sites less likely than many to have planning / visual amenity problems


Excess electrical energy may be fed into grid or stored (in batteries, as hydrogen via electrolysis, as compressed air, as kinetic energy via flywheels, etc.)

PV generation is simpler and highly suited to industrial roofs

PV could fall dramatically in price with new technology, less likely for wind

TH

RE

AT

S

TABLE 28: SWOT ANALYSIS OF WIND TURBINE SYSTEMS – COSTS, MARKETING AND ECOLOGY


ST

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Wear is correlated with wind speed, so increased maintenance cost can be met from revenue. Some suppliers offer wind speed related support services.

Marketing aspects

Highly visible and recognisable signal of ‘green credentials’


Gearless designs quieter than others


Cost and time of wind speed survey

(> 1 year)

Non-negligible operating cost

Relatively high maintenance cost for offshore turbines

Strong demand from China likely to increase cost

Marketing aspects

Possible opposition from local residents and businesses due to light flicker, noise, visual amenity and (often unfounded) concerns over blade shedding, lightning strikes, bird mortality, etc.

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Rapid technology development is still reducing cost per kWh




Global market for turbines, related technologies and support service


Volatile input material costs (e.g. copper, rare earth magnets, semiconductors)


Opposition from public to wind turbines

Threat of subsidy removal due to opposition from the public

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2.1.10. HYDRO ELECTRICITY


Dr. Rick Greenough: DMU, Leicester, United Kingdom

Dr. Andy Wright: DMU, Leicester, United Kingdom


Hydropower systems are characterised by the head and the flow rate of water available at

the turbine. Head is the energy per unit mass of water, and it may be the result of height

difference between stationary water in a dam and the turbine (static head), the difference in

water velocity upstream and downstream of the turbine (dynamic head) or in some cases a

combination of the two. The turbine extracts energy from flowing water by reducing its head,

but where the available head is low the turbine may be designed for high flow rates to

maximise power output.

FIGURE 21: DIFFERENT TURBINE TYPES (SOURCE: ALSTOM)



Turbines may be classified as impulse turbines, which are usually specified for high head

sites; and reaction turbines, which are generally specified for medium and low head sites.

In the former (such as the Pelton and Turgo designs), jets of water are directed at shaped

buckets operating at atmospheric pressure and energy is extracted by changing the

momentum of the water. In the latter (such as the Francis or Kaplan designs) water is fed

into a flooded chamber containing fixed guide vanes and a runner, which extracts energy

from the water by reducing its pressure as it changes direction through the guide vanes and

the rotating runner. In reaction turbines, energy extraction is enhanced by a draft tube in

which cross sectional area increases after the turbine, reducing water velocity and

increasing the pressure difference across the runner.

The Kaplan (propeller) type of runner is used for low head, high flow situations and the

Francis for medium head, medium flow. Another type of low head design is the ‘run of the

river’ system in part of the water in a river is extracted into a small dam upstream before

passing through the turbine and re-joining the river downstream. Another device used in low

head sites is the Archimedean screw.

FIGURE 22: HYDROPOWER IS RELATED TO FLOW RATE AND HEAD (SOURCE: ENGINEERINGTOOLBOX)

As mentioned there are different types of turbines available, the following table shows their

typical site characteristics.



TABLE 29: APPLICATION AND PERFORMANCE RANGE OF DIFFERENT TURBINES [11]

Hydropower turbine type Typical site characteristics

Archimedean screw Low heads (1.5 – 5 m)

Medium to high flows (1 – 20 m³/s)

For higher flows multiple screws are used

Crossflow turbine Low to medium heads (2 – 40 m)

Low to medium flows (0.1 – 5 m³/s)

Kaplan turbine Low to medium heads (1.5 – 20 m)

Medium to high flows (3 – 30 m³/s)

For higher flows multiple turbines can be used

Pelton / Turgo turbine High heads (greater than 25 m)

Lower flows (0.01 – 0.5 m³/s)

Waterwheels Low heads (1 – 5 m) – though turbines often more appropriate for higher heads

Medium flows (0.3 – 1.5 m³/s)

Francis turbines No longer commonly used except in very large storage hydropower systems, though lots of older, smaller turbines are in existence and can be restored.

For older turbines: Low to medium heads (1.5 – 20 m)

Medium flows (0.5 – 4 m³/s)


Like wind power, hydropower is a very old form of renewable energy in which energy

extracted from moving water used to be used directly to drive industrial processes such as

grinding corn, irrigation, forging, timber cutting or textile spinning and weaving. In developed

countries, such applications have almost disappeared and hydropower is now used to

generate electricity for local use or to generate revenue by supplying the grid. There are

many large, high head hydro schemes at purpose built dams, which have existed for many

decades.

For industrial premises located near to a river, the potential use of hydropower is limited by

the availability of the required combination of head and flow rate and also by the variability

of flow, as shown on the flow duration curve for the river.


Even though they are often very cost-effective, large scale hydropower schemes are so

expensive that they are usually considered to be national infrastructure projects. The cost

of the proposed tidal barrage across the Severn estuary in the UK was estimated in

September 2013 to be £ 25 billion; however, the scheme would deliver energy more cheaply

than the ‘strike price’ agreed by the government for offshore wind. The UK government

estimate the levelised (life-cycle) cost of a 5 – 16 MW hydropower project to be £ 134 per

MWh compared to £ 121 per MWh for a 1 – 5 MW onshore wind power project.

The cost per kWh of energy for smaller hydropower systems decrease significantly with

scale, due to the large fixed-cost element of design, consenting and installation.



FIGURE 23: RELATIVELY HIGH COST OF SMALL HYDROPOWER SCHEMES (SOURCE: RENEWABLESFIRST.CO.UK)

TABLE 30: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR HYDRO ELECTRICITY


Potential or kinetic energy in water

Kinetic energy in rotating shaft (i.e. when used directly) or much more commonly

Electrical energy

Head (height difference and hence amount of energy)

Flow rate

Flow-duration curve

SWOT Analysis of hydro power systems for industrial applications

TABLE 31: SWOT ANALYSIS OF HYDRO POWER SYSTEMS – TECHNICAL ASPECTS


ST

RE

NG

HT

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Relatively simple, mature technology



Likely energy capture can be estimated accurately from measurement of head, survey of flow rate and hydrological data

More constant output than wind

Limited to relatively few sites (major weakness)

High head schemes unlikely to be located near to industry

Low head schemes usually have modest output (kW not MW)

Intermittency - may stop completely during droughts

Local grid connection may need strengthening for feed-in to distribution network

Significant engineering to install hydro scheme

May affect river amenity, fish movements etc.

WE

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PP

OR

TU

NIT

IES

Many industrial sites are located close to rivers

Small scale hydropower may be ideal for isolated buildings / regions

Possible in principle to regulate flow from storage pond, on larger schemes (storage)


PV and wind more likely to be viable

Mature technology, may ‘fall behind’ new developments in PV etc.

Climate change may increase variability of rainfall and droughts

TH

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TABLE 32: SWOT ANALYSIS OF HYDRO POWER SYSTEMS – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S


Costs per kWh similar to onshore wind but cheaper than PV and much cheaper than offshore wind

Run-of-the river schemes do not need expensive dam

Marketing aspects

Fairly visible and recognisable signal of ‘green credentials’ , although can be made almost invisible if necessary


Highly suitable for some developing countries


Extremely high cost of civil engineering work on large hydropower schemes means that many are national infrastructure projects

Smallest systems are disproportionally expensive due to the fixed-cost element related to permissions for water abstraction and civil engineering work

Marketing aspects

Possible opposition from local residents due to environmental and visual impact

Large hydropower schemes often seen as environmentally damaging (flooded villages, damage to animal habitats) and having an negative impact on those living downstream

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Some systems can take advantage of cheaper electricity prices to store energy by pumping water uphill for release through turbine at times of peak demand




Global market for turbines, related technologies and support services


Volatile input material costs (e.g. copper, rare earth magnets, semiconductors)


Threat of subsidy removal due to opposition from public

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2.1.11. GEOTHERMAL

Responsible Author:



Utilising low enthalpy geothermal energy, it is intended to exploit the ground as a

source / sink for thermal energy exchange employing a heat pump (possibly switched off in

cooling mode) for the thermal conditioning of buildings.

Typical layout

A certain number of vertical holes (boreholes) is drilled in the ground, with a diameter of

15 cm (6") and a depth of the order of 100 m each. Holes are placed at a distance of no less

than 6 m from each other, to avoid mutual interference. Within the holes, a closed network

of polyethylene pipes is installed, typically with a double-U configuration within each hole.

Different holes are typically connected in parallel. The undisturbed temperature of the

ground below 15 m of depth is not affected by seasonal variations and is of the order of the

mean annual external temperature at the given geographical site. For example, in the north

of Italy the ground temperature is of the order of 10 – 15°C. A mixture of water and propylene

glycol is circulated within the pipes, by a common hydraulic pump (typical hydraulic flow rate

of the order of 6 m3/h). This closed circuit is coupled to a water-water heat pump, which is

in turn coupled to a circuit on the building side (with storage, etc.). Typical (water-water

compression) heat pumps used in this context yield a COP > 4 in nominal conditions for

heating (0°C and 35°C on evaporator and condenser, respectively). In terms of primary

energy ratio (PER), applying a grid efficiency factor 𝜂𝐺 = 46% (average power plant

efficiency for the Italian system) one gets PER = COP × 𝜂𝐺 > 1.8. For large applications,

also absorption heat pumps can be considered, where PER > 1.7 is possible.

Sizing

The sizing of the plant is typically done to cover about 60 – 70% of peak power (heating),

while the rest is typically obtained with a back-up boiler. The power which can be extracted

from the ground is of the order of 50 W/m, in terms of borehole length. That is, in order to

get about 50 kW one needs 1,000 m of pipes, for example distributed with 10 boreholes

each with a depth of 100 m. For the positioning of the boreholes at the correct distance, a

certain amount of free ground is needed (≤ 30 m2 per borehole, so that for the considered

sizing about 300 m2 are needed). After deployment, the ground is however again available

for other purposes.

On the left side of Figure 24, a residential installation is shown. The double-U pipe within

the borehole heat exchanger is clearly visible. Other layouts for the connection from the heat

pump to the building are possible. On the right side, a possible layout for a commercial

building is reported.



FIGURE 24: PRINCIPLE OF LOW TEMPERATURE GEOTHERMAL SYSTEM (SOURCES: JER)

In Figure 25, an example of a possible layout for double operation mode is shown (in free

cooling mode the heat pump is completely bypassed).

FIGURE 25: WORKING CONDITIONS OF GEOTHERMAL SYSTEMS FOR HEATING AND COOLING (SOURCE: CALEFFI)




For the integration of low-enthalpy geothermal energy, two aspects have to be considered.

Ground occupation. The installation of boreholes requires the availability of a

significant ground area. However, after the completion of the installation, the external

ground surface becomes again available and it can be used rather freely. For typical

factories it is not uncommon to have a good ground availability (parking areas etc.)

which could be temporarily used for the installation of boreholes.

The exploitation of geothermal energy occurs through ground source heat pumps.

These are standard machines, whose space occupation and connection with internal

heating and/or cooling plants does not present significant issues.

Considering the low-temperatures at play in low-enthalpy geothermal systems, only space

conditioning applications can reasonably be considered (no process heat).


Economic costs. Installation costs are mainly due to drilling costs and heat pump costs.

Other installation costs are given by piping costs, hydraulic pumps costs, thermal storage

costs, heat exchangers costs. As the latters are less significant and shared by common

thermal units, we do not specify them here. For large plants (>30 kW thermal), a so-called

ground response test (GRT) is recommended, to measure the average thermal conductivity

of the ground (which can otherwise be estimated on the basis of literature data). The GRT

is performed on the first borehole and allows to properly size the rest of the geothermal field.

The cost of this test is hence expected to be worth in consideration of the savings it yields

due to the better system sizing.

Drilling costs: of the order of 40 – 70 €/m, depending on borehole depth and terrain

type (typical cost in the north of Italy).

Heat pump costs: of the order of 5,000 – 10,000 € for 10 kW of thermal output power

(electric driven compression heat pumps, prices depend on size and COP and can

be highly variable for custom applications).

GRT costs: about 1,500 – 2,000 € (typical cost in the north of Italy).

Typical ROI time is estimated to be about 5 – 7 years. Real operation data show that the

typical COP for actual applications is closer to 3 than to 4.

Operation costs are mainly due to the electric consumption of the heat pump. A smaller

contribution to electric consumption is also given by hydraulic pumps.

The system’s life expectancy is very long. The network of polyethylene pipes is expected to

last at least 50 years. For mechanical and electric components, one should instead consider

the usual lifetime for these objects.



TABLE 33: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR GEOTHERMAL


Ground thermal source / sink

Electricity / Fuel (for the operation of the thermodynamic cycle)

Fuel (for back-up auxiliary heater)

Outlet temperature

Temperature lift

Heating demand (peak power)

Hot water demand (peak power)

Cooling demand (peak power)

COP heating (0 – 35°C)

COP hot water (0 – 50°C)

COP cooling or EER (30 – 18°C)

Seasonal performance factor (SPF), if possible

Flow rates in different circuits

SWOT Analysis of geothermal systems for industrial applications

TABLE 34: SWOT ANALYSIS OF GEOTHERMAL SYSTEMS – TECHNICAL ASPECTS


ST

RE

NG

HT

S

The installation does not interfere with buildings or processes (but relies on the temporary availability of external area).

Ground source heat pumps have a higher COP than air source heat pumps, mainly due to the smaller temperature difference between the ground source / sink and the conditioning plant than between the external environment and the conditioning plant (the ground is indeed warmer than external air in winter and cooler than external air in summer).

Free cooling in the ground can be possible under certain conditions (yielding a very high seasonal Energy Efficiency Ratio (EER)).

Differently from solar or wind energy, ground energy is not intermittent.

With respect to traditional heating solutions, heat pumps offer the possibility to be reversed for cooling (not to mention free cooling).

The output temperature has to be kept low or the COP is strongly reduced (difficult coupling with old heating plants, better for radiant panels or floor heating).

The technology cannot be installed in special areas (legal restrictions are present in the proximity of springs or thermal).

COP and EER are typically provided for the heat pump only: also hydraulic pumps consumption (at least on the ground side) should however be considered for the whole energy balance

Attention has to be paid to the interaction with underground structures (piping, cables, parking).

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Several possible applications in industrial sectors where large space conditioning is required (consider for example the food sector).

The waste heat of some processes could be applied to an absorption heat pump (which can be convenient with respect to a compression heat pump for large systems; see for example district heating applications in Denmark).

Coupling with PV for self-consumption.

Coupling with solar thermal systems for seasonal storage (non-mature solution).

Though the vertical borehole solution is the most diffused, several other layouts can be considered: horizontal circuits (saving drilling costs, but decreasing efficiency and requiring larger areas), circuits integrated with house foundations (saving drilling costs, but impossible for existing buildings), open circuits for direct exchange with rivers/lakes (improving efficiency, but increasing environmental issues).

The efficiency of the system depends on the ground properties (typically not a dramatic effect, however).

In climates where only heating or cooling is needed, the local ground temperature can be changed in a non-negligible way after several years of operation, reducing efficiency (however, simulations and experimental surveys have shown that this is also not a dramatic effect if proper sizing is done).


Concern about the use of water-glycol mixtures (though propylene glycol is anyway non-toxic).

TH

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TABLE 35: SWOT ANALYSIS OF GEOTHERMAL SYSTEMS – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S


Large installations are more cost effective than small installations, which, like in the case of commercial buildings, could apply well to some manufacturing companies.

The duration of the ground circuit is very long.

Good cost expectation, even without incentives.

Marketing aspects

No visual impact (advantage with respect to other RES).


Installation costs are high.

A non-negligible amount of space is needed (though less than for solar fields and with the possibility of re-using it after the conclusion of the installation)

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Increase in fuel prices.


Convenient on the long run.

Opening of jobs, businesses and companies.






Scarce diffusion of information about this technology, at least compared to other RES.

Increasing performances and/or price lowering of air-air heat pumps (where economies of scale can be applied more easily).

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2.1.12. BIOMASS


Fredy Vélez: CARTIF, Boecillo, Spain

Javier Antolín: CARTIF, Boecillo, Spain

Luis Ángel Bujedo: CARTIF, Boecillo, Spain

Jesús Samaniego: CARTIF, Boecillo, Spain


Different conversion processes and technologies can be used to produce heat, electricity,

combined heat and power, chemicals or liquid fuels for transport from biomass:

Thermal conversion: combustion, gasification and pyrolysis.

Biological conversion: fermentation, digestion, etc.

Mechanical conversion: compression and pressing, chipping, etc.

The selection of one or another needs to be aligned to the nature and structure of the

biomass feedstock and the desired project outputs.

This part of the document related to biomass technologies only goes into detail on

combustion and gasification technologies to produce heat or electricity.

Direct Combustion

Industrial biomass combustion facilities can burn many types of biomass fuel, including

wood, agricultural residues, municipal solid waste, etc. Combustion technologies convert

biomass fuels into several forms of useful energy for industrial uses (hot and superheated

water, saturated and superheated steam and thermal oil). One can use this form of biomass

utilization for many purposes, such as space heating, heating through transfer liquids and

steam production for the generation of electricity or motive power [12 – 16].

Direct combustion is the best-established and most commonly used technology for

converting biomass to heat. During combustion, biomass fuel is burnt in excess air to

produce heat. The hot combustion gases are sometimes used directly for product drying,

but more usually they are passed through a heat exchanger to produce hot air, hot water or

steam.

The combustion efficiency depends primarily on good contact between the oxygen in the air

and the biomass fuel. The main products of efficient biomass combustion are carbon dioxide

and water vapour, however tars, smoke and alkaline ash particles are also emitted.

Minimization of these emissions and accommodation of their possible effects are important

concerns in the design of environmentally acceptable biomass combustion systems.

Biomass combustion systems, based on a range of furnace designs, can be very efficient at

producing hot gases, hot air, hot water or steam, typically recovering 80 – 90% of the energy

contained in the fuel. To cope with a diversity of fuel characteristics and combustion

requirements, a number of designs of combustion furnaces or combustors are routinely

utilized. Figure 26 shows a general scheme of a biomass combustion system.



FIGURE 26: BIOMASS BOILER SCHEME (SOURCE: WELLONSFEI.CA)

Gasification

Gasification is the thermal conversion of biomass into a low calorific to medium ‐ calorific

value combustible gas. This is achieved by reacting the biomass at high temperatures

(> 700°C), without combustion, with a controlled amount of oxygen and/or steam.

The resulting syngas (mainly carbon monoxide (CO) and hydrogen (H2)) can be burned in a

boiler for heat production, or alternatively, if the syngas is clean enough, it may be used for

power production in gas engines or gas turbines as a substitute for convention fuels such

as diesel, natural gas, propane and more. Syngas contains 70 to 80% of the energy originally

present in the biomass feedstock. Figure 27 shows a general scheme of a biomass

gasification system.

FIGURE 27: BIOMASS GASIFIER SCHEME (SOURCE: DOCKSIDE GREEN, VICTORIA CANADA)



The gasifier is essentially a chemical reactor where various complex physical and chemical

processes take place. There are many types of biomass gasifiers, where the most typical

are the updraft, downdraft and the fluidized bed (Table 36).

TABLE 36: TYPES OF GASIFIERS WITH THEIR CHARACTERISTIC PARAMETERS [13]

Temperature (°C) Tar Particles Capacity MWel.

Reaction Gas output (g/Nm3) (g/Nm3) (t/h) Min Max

Fixed Bed

Downdraft 1,000 800 Very low

(0.02 – 4)

Low

(0.1 – 0.2) 0.5 0.1 1

Updraft 1,000 250 Very high

(20 – 100)

Low

(0.1 – 1) 10 1 10

Fluidized Bed

Bubbling bed 850 800 Moderate

(1 – 15)

Very high (2 – 20)

10 1 25

Circulating bed 850 850 Low

(1 – 15)

Very high (10 – 35)

20 2 100


These technologies can be easily integrated in many industries with high demand of heat or

electricity, especially in which there are biomass residues (agriculture, wood, paper and

pulp, food-processing, etc.) taking advantage of these residues of the production process.

This has the dual benefits of lowering fuel costs and solving waste disposal issues.

Large production plants will likely be required to obtain favourable economy-of-scale effects

and reasonable production cost. Integrating biomass gasification / combustion processes

for large-scale production processes in existing industries may result in technical, energy-

related and economic benefits.

There are a few different options for integrating in the industrial production process:

Feedstock integration by utilizing existing internal biomass residues.

Energy integration, where internal energy streams, can be used for example for fuel

drying, pre-heating, etc.

Equipment integration, by co-utilizing existing or new up-scaled equipment.


Biomass combustion systems can be very efficient at producing hot gases, hot air, hot water

or steam, typically recovering 80 – 90% of the energy contained in the fuel. On the other

hand, in the gasification process, the syngas contains 70 to 80% of the energy originally

present in the biomass feedstock. These systems could be used to produce heat directly

with the performance stated before, or could be used to produce electricity through the

following power generation systems shown in Table 37.

In Table 37, depicts the main parameters of the different biomass systems, depending on

the technology that is used for the power generation.



TABLE 37: MAIN PARAMETERS ACCORDING TO POWER GENERATION TECHNOLOGY THAT USE BIOMASS FUELS

SYSTEMS

Characteristics Steam turbine

Gas turbine

Micro turbine

ICE Fuel Cell Stirling Engine

Power range

(MW)

50 – 250 0.5 – 40 0.3 – 250 < 10 < 1 < 0.2

Technology Combustion

Gasification

Gasification Gasification Gasification Gasification Combustion

Gasification

Conditioning of syngas

No High High Medium Very High No

Electrical efficiency (%)

15 –25 25 – 40 25 – 35 25 – 35 40 – 60 15 – 20

Market availability Many models Many models Few models Many models Starting to emerge

Starting to emerge

Installation costs (€/kWh)

250 – 570 500 – 1,500 800 – 1,500 600 – 1,150 2,200 – 4,000

750 – 7,500

Operation & maintenance costs (Cent/kWh)

0.3 0.45 – 0.8 0.6 – 1.5 0.6 – 2 0.7 – 3 0.7

The costs of these systems depend mainly on the technology, which is going to be implanted

in the industry. The selection of one or another will be according the needs of the industry

(power and thermal needs, budget available, etc.) and the availability and kind of biomass,

space for both storage and installation, etc.

In Table 38 the main inputs, outputs and general parameters for biomass combustion

systems are presented. A detailed comparative table with different parameters for each

biomass technology is presented in the Table 37.

TABLE 38: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR BIOMASS COMBUSTION SYSTEMS


Dry biomass feedstock (wood, agricultural waste, municipal solid waste, etc.)

Excess air

Hot and superheated water

Saturated and superheated steam

Thermal oil

Hot air / gases

Electricity (through a vapour turbine)

Generic biomass

(Calorific value ≈ 16.500 kcal/kg, density: 200 – 800 kg/m3)

Boiler efficiency: 80 – 90%

Table 39 presents the main inputs, outputs and general parameters for biomass gasification

systems. A detailed comparative table with different parameters for each biomass

technology is presented in Table 37.



TABLE 39: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR BIOMASS GASIFICATION SYSTEMS


Dry biomass feedstock that can be ground to a small size

Limited amount of oxygen / air or steam

Syngas (H2 + CO).

Heat (through a boiler)

Electricity (through a gas engine / turbine)

Heating value of syngas:

4 – 10 MJ/m³

Gasifier efficiency: 70 – 80%

SWOT Analysis of biomass heating systems for industrial applications

TABLE 40: SWOT ANALYSIS OF BIOMASS HEATING SYSTEMS – TECHNICAL ASPECTS


ST

RE

NG

HT

S

It is not necessary to have a backup system as the biomass boiler / gasifier is able to produce 100% of the heating needs.

Compatibility with conventional heating & existing distribution systems

Technology can be applied to all scales.

Industrial uses for high temperature heat and steam.

Substitute of fossil fuels

Biomass can be used in decentralized facilities.

Need for a place to store the biomass (ideally under cover to keep fuel dry).

Biomass boilers / gasifire larger than gas or oil equivalents

Need for an extra fuel handling equipment and sophisticated filter system

Need for a local fuel supplier

Access for the delivery lorry for the fuel supply

It is possible that planning permission will be required.

Need a flue which meets the regulations for wood-burning appliances.

Unless the biomass component is purely base load, the system should include a buffer tank.

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Improve the national energy security

Competing technologies


Regulations too demanding in terms of maintenance T

HR

EA

TS



TABLE 41: SWOT ANALYSIS OF BIOMASS HEATING SYSTEMS – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S


Affordable heating fuel: although the price of wood fuel varies, it is often cheaper than other heating options.

Energy savings (covering of own energy demand).

Almost independent of energy markets. Biomass fuels are less susceptible to price increases than traditional fuels such as oil and gas.

It can be established locally, without the need for long-distance transportation or import of raw materials.

Marketing aspects

Relatively good cost of primary energy saved.

Positive environmental profile – mitigation of CO2 emissions.

State of art equipment / system.

Ecology aspects

It uses agricultural, forest, urban and industrial residues to produce heat with less effect on the environment than fossil fuels.

Biomass production removes the same amount of CO2 from the atmosphere as is emitted from gasification and combustion.

Wood waste that would typically end up in landfills can be recycled and used as fuel for onsite biomass boilers / gasifiers to provide energy.


Initial costs are high compared with traditional gas or oil installations.

Increased maintenance costs (ash removal and periodical maintenance).

The cost of fuel varies according to the distance to the supplier.

Biomass is bulky compared to other sources of energy. This makes transportation challenging and costly.

Marketing aspects

Lack of strong market deployment measures, harmonisation, and long-term commitment with the biomass.

There are at present a few industrial scale biomass gasification plants.

Ecology aspects

Produces air pollution, in some cases at levels above the traditional fuels.

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Independence on foreign energy


Available financial incentives

European Union firmly committed by renewable energy


The use of biomass creates direct jobs in manufacturing, engineering, installation, ongoing operation and maintenance, and many other areas. In addition creates indirect jobs in the industry’s supply chain and other supporting industries.

Emerging market on expansion phase

There is an increasing improvement of the social image of the new energies.


Increase of the price of biomass

Disappearance of incentives

Bad economic situation


Competition of fossil fuels as a cheaper alternative in many parts of the world



Competition for raw material with large wood industry

Pressure from the groups linked to the energy sector

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2.1.13. COMBINED HEAT AND POWER / CHP (BIOGAS)





Jesús Samaniego:, CARTIF, Boecillo, Spain


Combined Heat and Power (CHP) plants (also named cogeneration) produce electricity and

useful heat from different energy sources, in this case “biogas” [12, 17 – 23]. It represents a

highly efficient method of generating energy.

A cogeneration system is the sequential or simultaneous generation of multiple forms of

useful energy (usually mechanical and thermal) in a single, integrated system. CHP systems

consist of a number of individual components – prime mover (heat engine), generator, heat

recovery, and electrical interconnection – configured into an integrated whole. The type of

equipment that drives the overall system (i.e. the prime mover) typically identifies the CHP

system. Prime movers for CHP systems include reciprocating engines, combustion or gas

turbines, steam turbines, micro-turbines, and fuel cells. Although mechanical energy from

the prime mover is most often used to drive a generator to produce electricity, it can also be

used to drive rotating equipment such as compressors, pumps, and fans. Thermal energy

from the system can be used in direct process applications or indirectly to produce steam,

hot water, hot air for drying, or chilled water for process cooling.

Biogas is the product of the anaerobic fermentation of organic material in a fermenter.

Anaerobic digestion for methane production is mainly used as a waste processing technique

for biomass with high nitrogen and low lignin content. The biological breakdown of this waste

will produce CO2 and CH4 (45 – 75%) Anaerobic digestion residues can be returned to the

landscape to help close nutrient cycles and be a net benefit where land is used for food

production.

Anaerobic digestion can occur at mesophilic (35 – 45˚C) or thermophilic temperatures

(50 – 60˚C). After fermentation the biogas is normally cooled, dried of water vapour and

cleaned of hydrogen sulphide to produce a good combustion gas for gas engines. Also the

raw biogas can be cleaned and upgraded to methane; it is then called biomethane, and in

this pure form can be compressed and injected into gas grids or used as transport fuel.

The biogas produced is introduced to an engine or turbine to produce work (or electricity).

Exhausted combustion gases emerging from this process can be used, in part, to maintain

a condition of optimum temperature in the digester and the substrate. The rest could be

used for heating purposes, i.e., a biogas CHP plant. However, there is a tremendous amount

of waste heat that cannot be used sometimes, due to its characteristics and the location of

these plants.



FIGURE 28: SYSTEM SCHEME OF A CHP PLANT WITH BIOGAS AS FUEL (SOURCE: ZORG-BIOGAS.COM)

CHP systems are normally classified according to the sequence of energy use and the

operating schemes adopted. On this basis, CHP systems can be classified as either a

topping or a bottoming cycle.

In a topping cycle, the fuel supplied is used to first produce power and then thermal energy,

which is the by-product of the cycle and is used to satisfy process heat or other thermal

requirements. Topping cycle cogeneration is widely used and is the most popular method of

cogeneration.

In a bottoming cycle, the primary fuel produces high temperature thermal energy and the

heat rejected from the process is used to generate power through a recovery boiler and a

turbine generator. Bottoming cycles are suitable for manufacturing processes that require

heat at high temperature in furnaces and kilns, and reject heat at significantly high

temperatures. Typical areas of application include cement, steel, ceramic, gas and

petrochemical industries. Bottoming cycle plants are much less common than topping cycle

plants.


A Majority of industries require both electrical and thermal energy. Today most of them buy

power directly from the grid, or generate their own power through fossil fuel generators and

meet their thermal energy requirements mostly utilizing fossil fuels systems. As fossil fuels

are limited, and have adverse environmental impact, it would be appropriate to use non-

conventional energy sources such as organic material residues for generation energy in the

industries through biogas CHP plants.



These technologies can be easily integrated in many industries with high demand of both

electricity and heat, especially in which there are organic residues (farms, food-processing,

sewage, etc.) taking advantage of these residues (animal manures, agricultural residues,

waste water and other organic materials) of the production process. This has the dual

benefits of lowering fuel costs and solving waste disposal issues.


and reasonable production cost. Integrating CHP biogas processes for large-scale

production processes in existing industries may result in technical, energy-related and

economic benefits.


Feedstock integration by utilizing existing internal organic residues.

Energy integration, where internal energy streams, can be used for example for

heating the digester, etc.



When both thermal and electrical processes are compared, a CHP system typically requires

only three-fourth the primary energy compared to separate heat and power systems. This

reduced primary fuel consumption is the main environmental benefit of CHP, since burning

the same amount of fuel more efficiently means fewer emissions for the same level of output.

For example, facilities that produce electricity from steam-driven turbine-generators have a

conversion efficiency of 15 to 25%. Using a boiler to produce both heat and electricity

(cogeneration) improves overall system efficiency to as much as 90%. That is, CHP converts

90% of the fuel’s potential energy into useful energy

The energy content of raw biogas varies between 5 and 7 kWh/Nm3 of biogas depending on

the composition; as an average 6 kWh/Nm3 biogas is assumed (i.e., assuming 60% methane

content). For pure biomethane the energy content is approximately 10 kWh/Nm3.

In industrialized countries, power generation is the main purpose of most biogas plants;

conversion of biogas to electricity has become a standard technology. To improve overall

efficiency of biogas utilization, combined heat and power plants are often used, with part of

the heat utilized for maintaining reactor temperature and sometimes for heat treatment of

the incoming material.

The costs of these systems depend mainly on the technology which is going to be implanted

in the industry (Table 42). The selection of one or another will be according the needs of the

industry (power and thermal needs, budget available, etc.) and the availability and kind of

organic material, space, etc. The success of any biogas CHP project is heavily dependent

on the availability of a suitable organic biomass feedstock freely available (food processing

residues, animal manure, etc.).



TABLE 42: MAIN PARAMETERS ACCORDING TO POWER GENERATION TECHNOLOGY THAT USE BIOGAS


Gas turbine

Micro-turbine


Power range

(MW)

0.05 – 250 0.5 – 40 0.03 – 1 < 5 < 1 < 0.2

Conditioning of biogas



5 – 30 22 – 36 22 – 30 22 – 45 30 – 63 5 – 45


Starting to emerge

Installation costs (€/kW)

250 – 570 500 – 1,500 800 – 1,500 600 – 1,150 2,200 – 4,000

750 – 7,500


0.3 0.45 – 0.8 0.6 – 1.5 0.6 – 2 0.7 – 3 0.7

In Table 43 the main inputs, outputs and general parameters for Biogas CHP systems are

presented. A detailed comparative table with different parameters for each CHP technology

is shown in Table 42.

TABLE 43: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR BIOGAS CHP SYSTEMS


Organic material with high nutrient and water content (Humidity 60 – 90%)

Biogas / Biomethane

Biosolids

Heat & Electricity (through a biogas engine or turbine)

CH4: 45 – 70%

Fermenter efficiency: 85%

Average Biogas calorific value:

6 kWh/Nm³

Average Biomethane calorific value: 10 kWh/Nm³



SWOT Analysis of biogas CHP for industrial applications

TABLE 44: SWOT ANALYSIS FOR BIOGAS CHP UNITS – TECHNICAL ASPECTS


ST

RE

NG

HT

S

Compatibility with conventional heating / cooling & existing distribution systems.

Methane burns with a clean and pure flame, which means that boilers and other equipment are not clogged by soot and cinders.

Simultaneously generate electricity and useful heat.


Substitute of fossil fuels.

Production of a low-carbon fertiliser.

Biogas (Biomethane) has properties similar to natural gas.

Thermodynamically efficient use of fuel. Conventional power generation discards up to 65% of energy potential as waste heat, while cogeneration plants have a conversion efficiency of 75 – 90%.

Proximity of the average cogeneration facility, compared to the 5 – 10% loss in transmission of electricity from typically remote traditional power stations.

Particularly useful in colder climates where the heat can be used for heating buildings and industrial processes.

CHP technology is technologically and economically proven.

They reduce the risk of electric grid disruptions and enhance energy reliability.

CHP systems are typically scalable according to a facility’s electrical and thermal needs.

Biogas is far more difficult to store and transport than liquid fuels and requires more storage space due to its substantially lower energy density.

Possibly unpleasant odour made of substrates.

Biogas is explosive and needs to be stored carefully.


WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S Isolated buildings / regions.

Future building integration.

Methane is a fuel in demand by industry; partly because it is a gas that gives a high quality combustion that can be precisely controlled.

Improve the national energy security.

The infrastructure of natural gas can be used for biogas applications without modifications.

Competing against a wide range of more wellknown and established technologies.

Already installed conventional systems in existing industries (non-worthy replacement).

Regulations too demanding in terms of maintenance.

TH

RE

AT

S



TABLE 45: SWOT ANALYSIS FOR BIOGAS CHP UNITS – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S

Cost related parameters:

Independent of energy markets.

Affordable heating fuel, it is often cheaper than other heating options.

Utilizing organic wastes reduces the amount that must be transport to landfills.



Effluent from biogas digesters can serve as high quality organic fertilizer, displacing import or production of synthetic nitrogenous fertilisers.

Marketing aspects


Positive environmental profile – mitigation of CO2 emissions.

There exist large experiences for the production of biogas in order to use it in combined heat and power utilities.

Environmental

Cogeneration plants that produce power using biogas prevent emissions that would otherwise be emitted during the combustion of fossil fuels.

Biogas produced on a sustainable basis can significantly reduce greenhouse gas (GHG) emissions.

Anaerobic digestion serves to reduce the volume of wastes and the associated problem of their disposal.



Non-negligible operating cost.

Relatively high maintenance cost.

Dependence on substrate price (if substrates are bought in addition).


Generally inadequate and unreliable government support policies.

Marketing aspects

Non-adequately trained technical personnel.

Lack of information about the possibilities of biogas.

No common European quality standard exists for biogas.

Regulation of some countries restricts the auto-consumption W

EA

KN

ES

SE

S



SWOT COSTS, MARKETING AND ECOLOGY O

PP

OR

TU

NIT

IES


Increase in fossil fuel prices.

Reduction in dependence on foreign energy.

Excess electricity can be sold to a utility if agreements and protocols can be arranged.

CHP systems can also provide saleable steam and heat to other industry.

Energy bill savings and additional revenue streams (e.g.: clean energy credits) provided by CHP systems can be reinvested in facilities (or companies at large) to support facility expansion and other capital projects.


Available financial incentives.

European Union firmly committed by renewable energy.


The use of biogas creates direct jobs in manufacturing, engineering, installation, ongoing operation and maintenance, and many other areas. In addition, creates indirect jobs in the industry’s supply chain and other supporting industries.

Injection into the gas grid after upgrading to biomethane. Biogas could cover around one quarter of the present consumption of natural gas (fossil methane gas).

Transportation fuel after upgrading, compressing. Biogas is already introduced as transport fuel in several European countries.


There is tremendous potential for greater deployment of CHP in industrial and large commercial / institutional applications.

Emerging market on expansion phase.


Disappearance of incentives.

Bad economic situation.


Consumers are not used to this type of fuel.

Competition of natural gas as a cheaper alternative in many parts of the world.

Public perceptions of energy from waste currently poor.

TH

RE

AT

S



2.1.14. CHP (WOOD PELLETS / CHIPS)







Combined Heat and Power (CHP) plants (also named cogeneration), produce electricity and

useful heat from different energy sources, in this case solid biomass (wood pellets / chips).

It represents a highly efficient method of generating energy [12, 16, 17, 19 – 22, 24].












Biomass as fuel in a CHP system is an example of how renewables energy and power

generation systems can be combined. CHP systems, fed with solid biomass, are based on

external combustion engines technology. The solid biomass resource can take a variety of

forms and shapes such as agricultural residues, wood wastes from forestry and industry,

residues from food and paper industries, green municipal solid waste (MSW), dedicated

energy crops, reclaimed wood, etc. Figure 29 shows a general scheme of a biomass CHP

system.



FIGURE 29: SCHEME OF A BIOMASS COGENERATION SYSTEM (SOURCE: CARTIF)







cogeneration.







plants


Majority of industries require both electrical and thermal energy. Today most of them buy

power directly from the grid, or generate their own power through fossil fuel generators and

meet their thermal energy requirements mostly utilizing fossil fuels systems. As fossil fuels

are limited, and have adverse environmental impact, it would be appropriate to use non-

conventional energy sources such as biomass residues for generation energy in the

industries.

These technologies can be easily integrated in many industries, especially in which there

are biomass residues (agriculture, wood, paper and pulp, food-processing, etc.) taking

advantage of these residues of the production process. This has the dual benefits of

lowering fuel costs and solving waste disposal issues.




and reasonable production cost. Integrating biomass CHP processes for large-scale

production processes in existing industries may result in technical, energy-related and

economic benefits.


Feedstock integration by utilizing existing internal biomass residues.

Energy integration, where internal energy streams, can be used for example for fuel

drying, pre-heating, etc.










90% of the fuel’s potential energy into useful energy.

The costs of these systems depend mainly on the technology, which is going to be implanted

in the industry (Table 46). The selection of one or another will be according the needs of the

industry (power and thermal needs, budget available, etc.) and the availability and kind of

biomass, space, etc. The success of any biomass-fuelled CHP project is heavily dependent

on the availability of a suitable biomass feedstock freely available (forest residues, wood

wastes, crop residues, energy crops, etc.).

TABLE 46:MAIN PARAMETERS ACCORDING TO POWER GENERATION TECHNOLOGY THAT CAN USE BIOMASS AS FUEL


Gas turbine

Micro-turbine


Power range (MW) 0.05 – 250 0.5 – 40 0.03 – 1 < 10 < 1 < 0.2

Technology Combustion

Gasification

Gasification Gasification Gasification Gasification Combustion

Gasification

Conditioning of syngas



15 – 25 25 – 40 25 – 35 25 – 35 40 – 60 15 – 20


Starting to emerge

Installation costs (€/kW)

250 – 570 500 – 1,500 800 – 1,500 600 – 1,150 2,200 – 4,000

750 – 7,500


0.3 0.45 – 0.8 0.6 – 1.5 0.6 – 2 0.7 – 3 0.7



In Table 47 is presented the main inputs, outputs and general parameters for Biomass CHP

systems. A detailed comparative table with different parameters for each CHP technology

is presented in Table 46.

TABLE 47: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR BIOMASS CHP SYSTEMS


Dry biomass feedstock (wood, agricultural waste, municipal solid waste, etc.)

Air

Power (mechanical / electricity)

Steam

Type of biomass

(Calorific value ≈ 4,000 kcal/kg)

Density: 200 – 800 kg/m³

Global efficiency: 80 – 90%

SWOT Analysis of solid biomass CHP for industrial applications

TABLE 48: SWOT ANALYSIS FOR SOLID BIOMASS CHP UNITS – TECHNICAL ASPECTS


ST

RE

NG

HT

S


Proximity of the average cogeneration facility, compared to the 5 – 10 % loss in transmission of electricity from typically remote traditional power stations.


CHP technology is technologically and economically proven.

Thermodynamically efficient use of fuel. Conventional power generation discards up to 75% of energy potential as waste heat, while cogeneration plants have a conversion efficiency of 80 – 90%.



Substitute of fossil fuels.

They reduce the risk of electric grid disruptions and enhance energy reliability.

CHP systems are typically scalable according to a facility’s electrical and thermal needs.

Need for a place to store the biomass (ideally under cover to keep fuel dry).

Biomass cogeneration systems are larger than gas or oil equivalents.

Need for an extra fuel handling equipment and sophisticated filter system.

Need of a local fuel supplier.

Access for the delivery lorry for the fuel supply.


Unless the biomass component is purely base load, the system should include a buffer tank.

Need a flue which meets the regulations for wood-burning appliances. W

EA

KN

ES

SE

S

OP

PO

RT

UN

ITIE

S

Isolated factories / buildings / regions

Future building / industrial integration

Improve the national energy security

Competing against a wide range of more well-known and established technologies.


Regulations too demanding in terms of maintenance. T

HR

EA

TS



TABLE 49: SWOT ANALYSIS FOR SOLID BIOMASS CHP UNITS – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S


Almost independent of energy markets. Biomass fuels are less susceptible to price increases than traditional fuels such as oil and gas.



Affordable heating fuel: although the price of wood fuel varies, it is often cheaper than other heating options.

Marketing aspects

Relatively good cost of primary energy saved


State of art equipment / system.

Ecology aspects

CO2 neutral energy production.

It uses agricultural, forest, urban and industrial residues to produce heat with less effect on the environment than fossil fuels.

Wood waste that would typically end up in landfills can be recycled and used as fuel for onsite cogeneration plants to provide power and steam / heat for operations.



Increased maintenance costs (ash removal and periodical maintenance check).

The cost of fuel varies according to the distance the supplier has to travel.

Biomass is bulky as compared to other sources of energy. This makes transportation challenging and costly.

Marketing aspects

Lack of strong market deployment measures, harmonisation, and long-term commitment.

Ecology aspects

Produces air pollution, in some cases at levels above the traditional fuels.

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S


Increase in fossil fuel prices.

Reduction in dependence on foreign energy.


CHP systems can also provide saleable steam and heat to other industry.

Energy bill savings and additional revenue streams (e.g.: clean energy credits) provided by CHP systems can be reinvested in facilities (or companies at large) to support facility expansion and other capital projects.



European Union firmly committed by renewable energy.


The use of biomass creates direct jobs in manufacturing, engineering, installation, ongoing operation and maintenance, and many other areas. In addition, creates indirect jobs in the industry’s supply chain and other supporting industries.


There is tremendous potential for greater deployment of CHP in industrial and large commercial / institutional applications.

Emerging market on expansion phase.


Disappearance of incentives.


Increase of the price of biomass.


Competition with fossil fuels as a cheaper alternative in many parts of the world.

Consumers are not used to this type of fuel.

Public perceptions of energy from waste currently poor.

Competition for raw material with large wood industry.

Pressure from the groups linked to the energy sector.

TH

RE

AT

S



2.2. STORAGE SYSTEMS

2.2.1. THERMAL ENERGY STORAGE

Responsible Author:

Dr. Alice Vittoriosi: EURAC, Bolzano, Italy

General aspects

Energy storage is the stocking of some form of energy that can be drawn upon at a later

time to perform some useful operation. Energy can be stored in thermal form by heating or

cooling liquids or solids. Thermal energy storage (TES) systems can help balance energy

demand and supply, reducing the peak demand while increasing the overall efficiency of

energy systems.

TES systems can be either centralised or distributed systems. Distributed devices are mostly

in the range of a few to tens of kW and are usually buffer storage systems to accumulate

solar heat to be used for domestic and commercial buildings (e.g. hot water, heating,

appliances). Centralised plants are designed to store waste heat from large industrial

processes, conventional power plants, combined heat and power plants and from renewable

power plants, such as CSP. Their power capacity ranges typically from hundreds of kW to

several MW (i.e. thermal power). In particular, in the industrial sector about 5% of the final

energy consumption is assumed to be used by TES installations. Due to the increase in

fossil fuel prices, this figure is expected to rise in the next future.

An energy storage system can be described in terms of the following parameters:

Capacity: defines the energy stored in the system and depends on the storage

process, the medium and the size of the system;

Power: defines how fast the energy stored in the system can be discharged (and

charged);

Efficiency: is the ratio of the energy provided to the user to the energy needed to

charge the storage system. It accounts for the energy loss during the storage period

and the charging / discharging cycle;

Storage period: defines how long the energy is stored and lasts hours to months (i.e.

hours, days, weeks and months for seasonal storage);

Charge and discharge time: defines how much time is needed to charge / discharge

the system;

Cost: refers to either capacity (€/kWh) or power (€/kW) of the storage system and

depends on the capital and operation costs of the storage equipment and its lifetime

(i.e. the number of cycles).



Based on the operation principle, three main types of TES can be identified, namely:

Sensible heat storages: based on storing thermal energy by heating or cooling a liquid

or solid storage medium (e.g. water, sand, oil, rocks); the amount of energy stored is

proportional to the system’s internal energy (i.e. temperature).

Latent heat storages: use phase change materials (PCM) (e.g. materials going from

solid to liquid state or from liquid to gaseous state); the amount of energy stored

corresponds to the fusion or vaporization heat of the employed material.

Thermo-chemical storages (TCS): uses reversible endothermic chemical reactions to

store and release thermal energy.

Of the three TES typologies listed above, sensible heat storages are the most mature

technology and are largely employed for both residential and industrial applications. With

respect to PCM and TCS systems they offer simpler operation and lower specific investment

costs.

Sensible heat TES systems

Sensible TES consists of a storage medium, a container (commonly a tank) and inlet / outlet

devices. Tanks must both retain the storage material and prevent losses of thermal energy.

Depending on the temperature level at which energy should be stored, different thermal

mediums can be employed for sensible heat TES systems (see Table 50).

TABLE 50: SENSIBLE HEAT THERMAL STORAGE MATERIALS WITH CORRESPONDING WORKING TEMPERATURE RANGES

Thermal storage medium Temperature level

Cold / Hot water 4 – 90°C

Steam 100 – 300°C

Oil 150 – 400°C

Concrete / Rocks Up to 500°C

Cast iron / steel 400 – 700°C

Cold / hot water storages

Water, due to its abundance, low cost and high specific heat is the most widely used storage

medium in the low-to-medium temperature range. Hot or chilled water is stored in tanks,

which vary in design depending on thermal performance, architectural and economic

constraints.

Hot water tanks serve as energy buffer storages in water heating systems based on solar

energy and in co-generation energy supply systems. This technology is also used in solar

thermal installations for DHW combined with building heating systems (Solar-Combi-

Systems). Large hot water tanks are used for seasonal storage of solar thermal heat in

combination with small district heating systems. These systems can have a volume up to

several thousand cubic meters. Charging temperatures are in the range of 80 – 90°C. The

usable temperature difference can be enhanced by the use of heat pumps for discharging

(down to temperatures around 10°C).

Chilled water storages are used for cooling in air conditioning systems in buildings and in

industrial applications, e.g. in gas turbines power plants to cool the inlet air.



Typical working parameters for hot water sensible heat storage systems are summarised in

Table 51.

Because of the modest temperature ranges involved, the storage of significant amounts of

thermal energy involves relatively large tanks, which must therefore be simple and cheap in

construction in order to be economically viable.

The architecture of hot / cold water TES may vary depending on the application. Two- or

three-tanks configurations are employed to keep the volume of the single tanks low and to

ensure that a constant supply temperature can be provided. However, due to its simplicity

and low-cost, the single stratified tank configuration (or thermocline storage) is the most

employed for low-to-medium temperature TES. In these systems, at the start of operation,

the storage tank is full of cold fluid. As thermal energy, becomes available, cold storage fluid

is withdrawn from the bottom of the storage tank and heated. The hot storage fluid is then

put back into the top of the storage tank. If properly done, the less dense hot storage fluid

will “float” on top of the cold storage fluid, creating what is termed a thermocline (see Figure

30).

FIGURE 30: PRINCIPLE OF A THERMAL ENERGY STORAGE (SOURCE: JER)

TABLE 51: CHARACTERISTIC PARAMETERS FOR A HOT WATER TES SYSTEM

Capacity Power Efficiency Storage period Cost

10 – 50 kWh/t 0.001 – 10 MW 50 – 90% d/m 0.1 – 10 €/kWh



Steam storages

In the temperature range 100 – 300°C the dominating heat transfer fluid is steam which is

needed at low or intermediate pressure in different industrial processes. Applications range

from food processing, manufacturing of construction materials and other commodities, to

the textile industry.

State of the art for thermal storage used in process heat applications is the steam

accumulator technology. Steam accumulators, also called Ruths storage systems, use

sensible heat storage in pressurized saturated liquid water. Steam is produced by lowering

the pressure of the saturated liquid during discharge. Figure 31 shows the characteristic

layout of a Ruths storage.

FIGURE 31: SCHEME OF A STEAM ACCUMULATOR – RUTHS STORAGE (SOURCE: DLR)

The volume-specific thermal energy density of steam accumulators depends on the

pressure drop during discharge. Characteristic values are in the range of 20 – 30 kWh/m³.

A particular application of steam accumulators is represented by their combination with CSP

plants (an example is given in Figure 32). If the steam production of the collector field

exceeds the demand of the turbine, the surplus steam is condensed in the steam

accumulator. During periods of reduced insolation, steam is taken from the steam

accumulator to support or replace the steam production of the solar field.

Even though steam accumulators can work with pressure up to 100 bar, typical applications

range between 2 and 20 bar. Since evaporation temperature and pressure are

approximately logarithmically connected, the non-linear increase of material requirements

deteriorates the economic efficiency of steam accumulators at higher pressures.

For process steam applications until 20 bar operation pressure and capacity from 100 kWh

to 1 MWh the investment costs are approximately in the range of 200 – 400 €/kWh thermal

capacity.



FIGURE 32: SIMPLIFIED SCHEME OF A SOLAR THERMAL POWER PLANT WITH DIRECT STEAM GENERATION (DSG) AND

INTEGRATED STEAM ACCUMULATOR (SOURCE: DLR)

Oil storages

When storage temperatures above 100°C are needed, mineral, synthetic or silicon oils

represent a valid alternative to water, since they can stand high temperatures (up to 400°C)

without requiring high operation pressures. Organic heat-transfer oils have been used in

high-temperature CSP systems to avoid the cost of high-pressure plumbing systems [25].

As for water, thermal oils allow the natural thermal stratification inside the storage tanks,

thanks to the density differences between hot and cold conditions. If no stratified storage is

installed, usually a two-tank configuration is employed (i.e. a cold and a hot tank are installed

separately). In Figure 33 the process scheme for a solar energy generation plant with a two-

tank oil storage system is showed.

FIGURE 33: PROCESS SCHEME OF A SOLAR ENERGY GENERATION PLANT WITH A DIRECT TWO-TANK THERMAL OIL

STORAGE SYSTEM (SOURCE: JER)



If oil is used both as hot thermal fluid (HTF) and storage material (as depicted in Figure 33),

the system is referred to as direct storage; when the thermal energy must be transferred

from the HTF (oil) to a second material, the system is referred to as indirect storage system.

The main drawback of employing oil as storage media (direct systems) is related to the high

cost of the oil itself. On the other hand, using oil in indirect systems requires intermediate

heat exchangers between the HTF and the TES media.

All heat-transfer oils employed in TES share a common set of problems. They all degrade

with time, and their degradation is accelerated if they are operated above their

recommended temperature Iimits for any length of time. Table 52 reports the main

properties of thermal oils used in TES systems.

TABLE 52: CHARACTERISTICS OF THERMAL OILS FOR TES SYSTEMS

Storage Medium

Temperature Average density

Average heat capacity

Costs per kg Costs per kWh Cold Hot

°C °C kg/m³ kWh/m³ US$/kg US$/kWh

Mineral oil 150 300 770 2.6 0.3 4.2

Synthetic oil 250 350 900 2.3 3 43

Silicon oil 300 400 900 2.1 5 80

Concrete / rocks TES

Sensible heat storage by solid media are usually used in packed beds, requiring a fluid to

exchange heat. They are also referred to as passive storage systems: the HTF passes

through the storage only for charging and discharging the solid material.

In a solid media sensible heat storage unit, a tube register heat exchanger with collectors

and distributors for the heat transfer fluid is embedded in the solid storage material. The

thermo-physical properties of the solid storage materials, such as density, specific heat

capacity, thermal conductivity, coefficient of thermal expansion (CTE), and cycling stability,

as well as availability, costs, and production methods are of great relevance. A high heat

capacity reduces the storage volume and a high thermal conductivity increases the

dynamics in the system. The CTE of the storage material should be similar to the CTE of

the material of the embedded metallic heat exchanger. A high cycling stability is important

for a long lifetime of the storage unit.

Figure 34 presents an example of solid storage system, where 2.54 cm diameter gravel

mixed with sand were used as storage media in combination with oil as HTF. The optimum

design for a rock storage can be difficult since the performance is affected by the shape,

size, density, specific heat, and other properties of the rocks used.



FIGURE 34: OIL PLUS ROCKS PASSIVE STORAGE SYSTEM (SOURCE: POWER FROM THE SUN.NET)

To improve the performance of solid media TES systems, concrete can be used instead of

rock-sand mixtures. The advantages of concrete systems lie in its high specific heat, good

mechanical properties (e.g. compressive strength), thermal expansion coefficient near that

of steel (pipe material) and high mechanical resistance to cyclic thermal loading. At the same

time, concrete still allows keeping the storage cost relatively low. Figure 35 shows the layout

of a CSP plant coupled with a concrete TES, while the main characteristics of rock and

concrete storage systems are listed in Table 53.

FIGURE 35: PROCESS SCHEMATIC OF A SOLAR ENERGY GENERATION PLANT WITH A CONCRETE TES

(SOURCE: W. D. STEINMANN, M. ECK)

TABLE 53: CHARACTERISTICS OF ROCKS AND CONCRETE TES SYSTEMS

Storage Medium Temperature Average density


Costs per kg

Costs per kWh Cold Hot

°C °C kg/m³ kWh/m³ US$/kg US$/kWh

Sand-rock mineral oil 200 300 1,700 1.3 0.15 4.2

Reinforced concrete 200 400 2,200 1.5 0.05 1



Cast iron / steel

A possibility to store heat at very high temperatures (up to 700°C) is to employ steel or cast-

iron ingots. Such TES systems consist of an assembly of pipes with rectangular external

cross sections. A thermal fluid or super-heated steam is passed through the pipes for

charging and discharging. It should also be possible to maintain a significant temperature

gradient along the length of the storage unit for several days. A schematic representation of

the working principle for a cast steel TES is given in Figure 36.

FIGURE 36: SCHEMATIC REPRESENTATION OF A CAST STEEL SENSIBLE HEAT STORAGE SYSTEM (SOURCE: JER)

This device has the advantage of great simplicity, it has virtually nothing to wear out, no heat

exchangers to clog, and no scarce or toxic materials are required. It also does not require

an external pressure vessel to contain the heat transfer fluid (the steel pipes provide the

needed containment). Up to now cast iron / steel TES systems have only been demonstrated

in pilot installations and proved to be too expensive, despite the thermodynamic advantages

offered over oil or concrete storage media. The characteristic parameters of cast iron / steel

TES are listed in Table 54.

TABLE 54: CHARACTERISTICS OF CAST IRON / STEEL FOR TES SYSTEMS

Storage Medium

Temperature Average density


Costs per kg

Costs per kWh Cold Hot

°C °C kg/m3 kWh/m3 US$/kg US$/kWh

Cast iron 200 400 7,200 0.56 1 32

Cast steel 200 700 7,800 0.6 5 60



SWOT analysis for cold / hot water storages

TABLE 55: SWOT ANALYSIS FOR COLD / HOT WATER STORAGES – TECHNICAL ASPECTS


ST

RE

NG

HT

S

Water has a very high volumetric specific heat capacity

Large availability of storage medium

Versatile technology for low temperature applications (can be easily sized according to necessity)

Allows thermal stratification improving the system efficiency

Limited to low temperature applications (< 95°C)

To store large amounts of energy large storage volumes are needed

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S

Increasing employment of RES systems Drinking water storage systems have to comply strict anti-legionella regulations (need of working temperatures above 60°C)

TH

RE

AT

S

TABLE 56: SWOT ANALYSIS FOR COLD / HOT WATER STORAGES – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S

Water has a very high volumetric specific heat capacity

Large availability of storage medium

Versatile technology for low temperature applications (can be easily sized according to necessity)

Allows thermal stratification improving the system efficiency

Limited to low temperature applications (< 95°C)

To store large amounts of energy large storage volumes are needed

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S

Increasing employment of RES systems Drinking water storage systems have to comply strict anti-legionella regulations (need of working temperatures above 60°C)

TH

RE

AT

S



SWOT analysis for steam storages

TABLE 57: SWOT ANALYSIS FOR STEAM STORAGES – TECHNICAL ASPECTS


ST

RE

NG

HT

S High volumetric heat capacity (same as

water)

Can directly feed industrial processes using steam

Can work at higher temperature with respect to simple water storage systems

Work under high pressure and need a dedicated pressurized equipment for charge and discharge

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S

Could be coupled with CSP solar systems

Employment of RES in industrial processes

Pressurized equipment increases the risk during system operation

TH

RE

AT

S

TABLE 58: SWOT ANALYSIS FOR STEAM STORAGES – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S Well-assessed technology

Widely used in industrial processes

More expensive than simple water tanks due to the need of pressurized equipment

For higher pressures (> 30 bar) the installations and running costs are too high

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S

Could help boosting the market for RES systems, mitigating the problem of discontinuous energy availability.

Due to the higher costs at higher pressure levels might be overcome by other technologies

TH

RE

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S



SWOT analysis for oil storages

TABLE 59: SWOT ANALYSIS FOR OIL STORAGES – TECHNICAL ASPECTS


ST

RE

NG

HT

S Can work at high temperature levels

Allow thermal stratification inside the tank

Thermal oil can be used also as hot thermal fluid in the system

Oil performance degrades with time and if the maximum temperature is exceeded

If oil is not used as HTF an intermediate heat exchanger is needed

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S

Can be coupled with CSP systems

Industrial processes requiring high temperature levels

Lack of know-how of plant designers and installers

Possible environmental threats for the release of oil in case of system leakages

TH

RE

AT

S

TABLE 60: SWOT ANALYSIS FOR OIL STORAGES – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S The storage medium is very costly

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S


Only few demo installations are available

TH

RE

AT

S



SWOT analysis for concrete / rock bed storages

TABLE 61: SWOT ANALYSIS FOR CONCRETE / ROCK BED STORAGES – TECHNICAL ASPECTS


ST

RE

NG

HT

S High storage temperatures achievable

Storage media has a long time stability and no degradation of performance

Need of a heat transfer fluid to charge and discharge

Need of an embedded heat exchanger for the hot thermal fluid

Large volumes needed

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S

Industrial processes requiring high temperature storages

Possibility of integration within concrete structures

High cycling stabilities can be reached only if the dimensioning of the embedded heat exchanger is properly done

TH

RE

AT

S

TABLE 62: SWOT ANALYSIS FOR CONCRETE / ROCK BED STORAGES – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S Storage material is very cheap High initial investments for the embedded

heat exchanger

Not very well assessed technology (only pilot installations available)

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S


TH

RE

AT

S



SWOT analysis for cast iron / steel storages

TABLE 63: SWOT ANALYSIS FOR CAST IRON / STEEL STORAGES – TECHNICAL ASPECTS


ST

RE

NG

HT

S High working temperatures allowed

Does not wear out and does not release toxic materials

Need of a heat transfer fluid to charge and discharge

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S

Can be coupled with processes that need very high exercise temperature

TH

RE

AT

S

TABLE 64: SWOT ANALYSIS FOR CAST IRON / STEEL STORAGES – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S Storage media much more expensive than

other passive storage systems (such as concrete)

Up to now only demonstrative installations available

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S


Availability of cheaper storage technologies

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2.2.2. ICE STORAGES





The ICE storage is one of the possible thermal energy storage considered by the European

Technology Platform on Renewable Heating and Cooling (RHC-Platform) as a “Cross –

cutting technology”.

Within the three main areas of thermal energy storage (sensible heat storage system, latent

heat storage system and thermo chemical heat storage system) the ice storage is classified

among the latent heat one.

The latent heat is termed by the amount of heat, which is absorbed or delivered by the phase

change of a material. The storage of latent heat is therefore connected with the change of a

given substance from one phase to another.

The abovementioned used materials can be water, paraffin or salt mixtures. In the following

table some characteristic parameters are shown:

TABLE 65: TRANSITION TEMPERATURE AND HEAT OF LATENT HEAT SUBTANCES [26]

Heat Storage Medium

Transition

from/ to

Transition (fusion) Temperature θf

[°C]

Transition (fusion)

Heat hf [kJ/kg]

Specific Heat Capacity

cp,s/cp,l [kJ/kgK]

Water Solid / liquid

Liquid / gaseous

0

100

335

2,540

2.1/4.19

4.19/1.86

Paraffin

Eicosane

Raw Paraffin

Solid / liquid

Solid / liquid

36.6

34.3

243

142

1.94/2.08

Salt mixtures:

48NaCl/52MgCl2

67NaF/33MgF2

Solid / liquid

Solid / liquid

450

832

432

618

0.9/1.0

1.42/1.38

From the possible transition forms of the abovementioned table, the solid to liquid one is the

most used. An example of ice storage is shown in Figure 37.

FIGURE 37: PICTURES OF AN ICE-STORAGE (SOURCE: SOLERA)



Inside the tank a special designed heat exchanger is integrated, made out of plastic, spirally

drawn through the whole storage and traversed by the heat transfer medium, which consists

of an ethylene mixture. The extraction of the low temperature heat is designed to force the

ice growing from the inside to the outside.

It is a seasonal storage system, which works by taking off heat by a heat pump in winter. In

this season the heat is taken off till the heat storage medium water changes from the liquid

phase into the solid phase (ice), therefore it is called ice storage. In summer this stored cold

is used to cool down, for example a building, until the ice is heated up and changes again

into the liquid phase. Then the cycle can start again.

FIGURE 38: SCHEME OF A SOLAR COOLING SYSTEM WITH A LATENT HEAT STORAGE (SOURCE: SOLERA)

TABLE 66: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR ICE STORAGES


Solar radiation

Back up system

Heating

Cooling

Specific heat capacity of ice:

1.377 – 2.1 kJ/(kg K)

Melting heat: 333.5 kJ/kg



SWOT Analysis of ICE storage systems for industrial applications

TABLE 67: SWOT ANALYSIS FOR ICE STORAGES – TECHNICAL ASPECTS


ST

RE

NG

HT

S

Increase the generation capacity

Water is a good / cheap phase change material

It offers storage densities 5 – 15 times greater than sensible storage



Water is no corrosive as the salt mixtures could be

The energy can be stored easier and cheaper than in a high temperature storage device due to the lower temperature delta of the storage and the environment.

Danger of tank burst due to the expansion of volume from the phase change of water.

Heat pump is needed

Space to install the storage is needed

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S

Chiller capacity can be reduced by 50% or more thanks to the reduction in the electrical peak loads



Standardization



TH

RE

AT

S

TABLE 68: SWOT ANALYSIS FOR ICE STORAGES – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S Marketing aspects




High storage costs

Marketing aspects




WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S


Possible available financial incentives per country


Opening of jobs, businesses, companies - companies - New geographic markets emerging outside the EU





None financial incentives or reduction of the existing financial incentives, ceasing the technology being attractive (e.g. Spain)


Legislation of the country supporting other technologies (e.g. Spain)




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2.2.3. PCM STORAGES



Andres Macia: CARTIF, Boecillo, Spain


To store thermal energy, sensible and latent heat storage materials are widely used. Latent

heat TES systems using PCM are useful because of their ability to charge and discharge a

large amount of heat from a small mass at constant temperature during a phase

transformation. Because high-melting-point PCMs have large energy densities, their use

can reduce energy storage equipment and containment costs by decreasing the size of the

storage unit. Using cascaded PCMs, with equally spaced melting points and with high

thermal properties, the TES is significantly enhanced. However, currently there is not

enough information on the thermal properties of molten salt systems at high temperatures.

A large number of phase change materials (organic, inorganic and eutectic) are available in

any required temperature range. A classification of PCMs is given in Figure 40. There are a

large number of organic and inorganic chemical materials, which can be identified as PCM

from the point of view melting temperature and latent heat of fusion. However, except for

the melting point in the operating range, majority of phase change materials does not satisfy

the criteria required for an adequate storage media as discussed earlier. As no single

material can have all the required properties for an ideal thermal-storage media, one has to

use the available materials and try to make up for the poor physical property by an adequate

system design. For example, metallic fins can be used to increase the thermal conductivity

of PCMs, supercooling may be suppressed by introducing a nucleating agent or a ‘cold

finger’ in the storage material and incongruent melting can be inhibited by use of suitable

thickness.

In general, inorganic compounds have almost double volumetric latent heat storage capacity

than the organic compounds. For their very different thermal and chemical behaviour, the

properties of each subgroup which affects the design of latent heat thermal energy storage

systems using PCMs of that subgroup are discussed in detail below [27].

A suitable phase change temperature and a large melting enthalpy are two obvious

requirements on a phase change material. They have to be fulfilled in order to store and

release heat at all. However, there are more requirements for most, but not all applications.

These requirements can be grouped into physical, technical, and economic requirements

[28, 29].

TABLE 69: CHARACTERISTICS OF PCM STORAGE

Physical Technical Economic

Suitable phase change temperature

Large phase change enthalpy

Reproducible phase change

Little subcooling

Good thermal conductivity

Low vapour pressure

Small volume change

Chemical stability of the PCM

Compatible with others materials

Safety constrains

Low price (less than 1 €/kg)

Good recyclability



FIGURE 39: CLASSES OF MATERIALS THAT CAN BE USED AS PCM AND THEIR TYPICAL RANGE OF MELTING

TEMPERATURE AND MELTING ENTHALPY (SOURCE: ZAE BAYERN)

FIGURE 40: PCM CLASSIFICATION (SOURCE: JER)



TABLE 70: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR PCM STORAGES


Thermal energy Thermal energy Phase change temperature: 10 – 800°C

Latent heat: 100 and 500 kJ/kg

Density: 750 up to 2,000 kg/m³

Stability to cycling depends on the type

Thermal conductivity depends on the type

SWOT Analysis of PCM storages for industrial applications

TABLE 71: SWOT ANALYSIS FOR PCM STORAGES – TECHNICAL ASPECTS


ST

RE

NG

HT

S

Reduce temperature fluctuation and cut peak temperatures

Low vapour pressure

High energy storage density

Eutectic water-salt solutions.

High thermal conductivity

Wide range temperature uses.

Chemically stable

Sharp melting temperature

Paraffin

Chemically stable and recyclable

No segregate

Save and non – reactive

Compatible with all metal containers

Salt hydrates

Lower volume change

High heat of fusion

Save and non – reactive

Sharp melting point

High thermal conductivity

Eutectic water-salt solutions.

Cycling stability

Phase separation

Low thermal conductivity

Relative large volume change

Lack of currently available test data thermo-physical properties

Segregation

Supercooling

Corrosive

Paraffin

Low thermal conductivity

Problem when high heat transfer rates

High volume change between solid to liquid

Flammable

Salt hydrates

Segregation

Supercooling

Corrosive

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NE

SS

ES

OP

PO

RT

UN

ITIE

S


Solar thermal power generation

Industrial process

Heat and power generation

Standardization


PCM based systems are currently still used in pilot projects and not integrated in household applications or industrial applications.

The market price for such systems is still too high. A forecast in regard to their social acceptance is not possible.

No fully assessed

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TABLE 72: SWOT ANALYSIS FOR PCM STORAGES – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S


Relative low cost

Marketing aspects


Available in a large temperature range


Too expensive to be used as heat storage media on large scale

Too high investment cost

High general installation cost

Marketing aspects

Today still more or less a subject of Research and Development (R&D)

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S








Opening of jobs, businesses, companies - companies - New geographic markets emerging outside the EU





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2.2.4. BATTERIE STORAGES


Iñigo Gandiaga: IKERLAN, Arrasate-Mondragón, Spain

Maider Usabiaga: IKERLAN, Arrasate-Mondragón, Spain

Aitor Milo: IKERLAN, Arrasate-Mondragón, Spain


Electric Energy Storage (ESS) systems allow decoupling and managing energy production

and demand in energy systems. They have an important potential to help improving the

global energy efficiency, to help increasing the RES integration level and contribute to the

mitigation of greenhouse gases in the industrial environment.

The main targets for ESS for this commitment will be the following:

To improve the RES intermittency and to store the generated excess energy to return

it when demand requires.

To store the energy from heat recovery (Cogeneration) systems and allowing their

operation following thermal loads or other efficiency strategies.

To keep and improve the power quality on isolated facilities and to supply ancillary

services to the main grid on, grid-connected installations.

To decrease facilities electrical bill.

These systems (RES and Cogeneration) provide themself primary energy savings, but

adding ESS to the system can be of help to increase those savings and facilitating the

implementation of the whole system.

In recent years, strong energy price escalation increased environmental awareness and

technological deployment in ESS technologies around portable and traction applications has

opened new horizons also for stationary applications in the industrial environment. New

Lithium-ion technologies are one of the most promising technologies for ESS. The

advantages of Li-ion are obvious: highest energy density and output power made this

technology very promising. At the current state of development however, Lithium-ion battery

(LiB) demand a cell level complex BMS and powerful cooling systems, and these issues can

become important barriers. NiMH, with around half of LiB´s energy density is a more mature

alternative: specific power can be even superior to LiB, but significantly lower efficiencies

and high self discharge is for example an issue for stationary applications. Price

development, calendar life, cycle life under realistic conditions and abuse tolerance in aged

battery packs need to be further investigated to have a clearer picture of which technology

will finally suit best different applications.

Lead acid batteries, on the other hand, give a chance for jumping into ESS with lower

investment costs and a mature, competitive and diverse market. The drawbacks are four to

seven times lower energy density, lower specific power (specially while charging, which can

be an issue connected to RES installations) and a reduced calendar and cycle life.

In applications where power capabilities are demanded rather than energy, Ultra caps could

also be an interesting technology: they have a very high power capacity and they can last



millions of charge/ discharge cycles without losing energy storage capacity. The main

shortcoming of super capacitors is their very low energy density, very high costs, and a

reduced market deployment.


FIGURE 41: SCHEMATIC REPRESENTATION OF THE INTEGRATION OF A BATTERY TOGETHER WITH A PV SYSTEM ON A

FACTORY LEVEL / DC-COUPLING (SOURCE: IKERLAN)



FIGURE 42: SCHEMATIC REPRESENTATION OF THE INTEGRATION OF A BATTERY TOGETHER WITH A PV SYSTEM ON A

FACTORY LEVEL / AC-COUPLING (SOURCE: IKERLAN)

Not only the technology selection, ESS technical dimensioning is the key issue for the

economic feasibility of storage systems. The sizing of the battery can be characterized by

the peak management -maximum power (W) demand- or designed in function of the

dynamic behaviour of RES generation -energy (Wh) need in a charge / discharge cycle-.

This selection will be made in function of the economic profit of each case based on RES

energy inputs, factory energy demand profiles and electricity tariffs and ESS economic

model itself.

TABLE 73: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR BATTERY STORAGES


Solar radiation

Industrial processes electricity consumption: AC / DC, voltage, current, load profile of at least 1 month, average day for each month (kW/min)

Electricity tariff breakdown: subscribed power capacity, energy price, hourly discrimination rate

Battery load power profile:

Average day power profile for each month (kW/min)

Battery discharge power profile:

Average day power profile for each month (kW/min)

Battery cost (€):

This outputs will be obtained from the battery economic parameters

Single cell nominal capacity and voltage, maximum power

Battery pack sizing, number of cells in series and parallel strings

Battery cost (€/kWh)

Battery life and operational parameters: life cycles vs DoD, charge and discharge efficiency, charge discharge nominal C-rate, charge discharge maximum continuous C-rate, charge discharge peak C-rate



SWOT Analysis of batterie storages for industrial applications

TABLE 74: SWOT ANALYSIS FOR BATTERIE STORAGES – TECHNICAL ASPECTS


ST

RE

NG

HT

S Extension of the use of existing RES

Less losses of transformation of electricity

Batteries efficiency

Best sizing result in longer durability and higher performance

ESS provides emergency power to a load when the input power source fails (UPS)

Large investment in power equipment required (dc/dc converters, dc/ac inverters, battery chargers)

Sophisticated Battery Management System (BMS) required for lithium batteries (no other technologies)

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S Isolated buildings / regions (Island mode)


The involvement of automotive industry should improve the technology

Storage of energy overproduction

Decrease the effect of RES intermittency

Provide services to the main grid (demand side services).

Failure of technical improvement expectations

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RE

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TABLE 75: SWOT ANALYSIS FOR BATTERIE STORAGES – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S


Relatively low operating cost

Almost independent of maintenance

Marketing aspects

Possible to work in island mode


Potential ability to provide ancillary services to the main grid.


High initial cost


Marketing aspects


WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S


Increase in fuel / electricity prices

The involvement of automotive industry should decrease the lithium-ion ESS kWh price

Decrease of electric bill

Benefit from electricity price hourly discrimination

Marketing aspects

Automotive industry could provide cheaper 2nd life batteries

Take part in energy market as overproduction energy seller


Failure of cost improvement expectations

Marketing aspects


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2.3. WASTE HEAT RECOVERY

2.3.1. ORGANIC RANKINE CYCLE (ORC)







The ORC operation principle is the same as the conventional Rankine cycle, but in this case,

the working fluid is an organic compound of low boiling point instead of water, thus

decreasing the temperature needed for evaporation. A pump pressurizes de liquid fluid,

which is injected into an evaporator (heat source) to produce vapour that is expanded in a

turbine connected to a generator. Finally, the output vapour is condensed and sucked up by

the pump to start the new cycle.

The heat is transferred to the ORC working fluid, either directly (direct exchange between

waste heat and working fluid) or indirectly (with an intermediate medium closed loop),

depending upon the characteristics of the waste heat source and other constraints.

Typically, waste heat liquid flows are directly coupled to the ORC cycle, while gas flows are

indirectly coupled.

FIGURE 43: DIAGRAM OF POSSIBLE APPLICATIONS OF ORC ACCORDING TO THE ENERGY SOURCE (SOURCE: CARTIF)

In the case of direct exchange, the heat source is simply connected to the ORC, which

converts part of the heat into electricity, as previously described. When an indirect heat



recovery scheme is employed, the heat source exchanges heat with an intermediate

medium (typically thermal oil or pressurised water), and afterwards feeds the ORC cycle.

The ORC performance depends on several factors such as the quantity of heat input, the

temperature and kind of thermal source, the cold source temperature and type (air or water),

working fluid and specific features of the thermodynamic cycle.

The selection of the working fluid for it use in ORC cycles is a crucial aspect because,

depending on the application, the source and the level of heat to be used, the fluid must

have optimum thermodynamic properties at the lowest possible temperatures and pressures

and also satisfy several criteria, such as being economical, nontoxic, non-flammable,

environmentally friendly, allowing a high use of the available energy form the heat source,

etc. [30, 31].

FIGURE 44: ORC INTEGRATED WITH A BIOMASS BOILER (SOURCE: TURBODEN)


The ORC system can be connected to the electricity network, where all the electricity is

delivered to the grid or just one part, and the rest is consumed in the same place where the

demand is produced. A battery is normally not needed.


TABLE 76: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR ORC SYSTEMS


Thermal energy

Electricity (Pump)

Condensation water

Electricity

Mechanical energy

Thermal energy (condensation water)

Cold (through an absorption / adsorption machine)

Power range: 0.2 – 3 MWel

Cost: 1 – 4x103 €/kWel

Heat source: 100 – 350°C

Condensation temperature: 60 – 120°C

Electrical efficiency ≈ 18%

Thermal efficiency ≈ 80%



SWOT Analysis of ORC systems for industrial applications

TABLE 77: SWOT ANALYSIS OF ORC SYSTEMS – TECHNICAL ASPECTS


ST

RE

NG

HT

S

Take advantage of low and medium temperatures to produce electrical and/or mechanical energy, due to the low ebullition temperature of the working fluid.

Possibility of using different low temperature heat sources for power generation.

ORC systems are very flexible and can be used in different applications.

Facilitate an electricity supply to unconnected areas (self-production of energy).

Increase the energy efficiency in the industrial sector using the waste heat of the processes.

Can be used as a bottoming cycle, taking advantage of the residual thermal energy, or as topping cycle generating electricity and using the remaining residual heat for the processes.

Can be used with a lot of different heat sources (solar, geothermal, biomass, waste heat, etc.).

No high pressure (< 30 bar) compared to steam cycle (60 – 70 bar).

Automatic and continuous working.

Removal of corrosion problems by not using water.

Simple start / stop procedures.

Quiet operation.

Reliability and high efficiency even at partial load (the plants automatically operate down to 10% of the nominal load).

The layout of the ORC is somewhat simpler than that of the steam Rankine cycle.

There is no need for superheating in ORC cycles, contrary to steam cycles. The absence of condensation also reduces the risk of corrosion on the turbine blades, and extends its lifetime.

ORC cycles enable the use of once-through boilers. No superheating is needed.

Compatibility with conventional energy distribution systems.

Reduce the risk of electric grid disruptions and enhance energy reliability.

Offers the possibility of co-generating on a small-scale.

Very high turbine efficiency (up to 85%).

Low mechanical stress of the turbine, due to low peripheral speed.

Low RPM of the turbine, allowing direct drive of the electric generator (without gear reduction).

No erosion of turbine blades and casing, due to absence of moisture in the vapour nozzles.

No particular qualification or know how is required for the personnel operating the plant.

The chemical stability of the fluid used can limit the temperature of the heat source, because it can be broken down when exposed to certain temperatures, producing substances that could modify the way in which the cycle works.

The low temperatures that are intended for use with the ORC make the overall efficiency of the cycle was highly sensitive to inefficiencies in heat transfer.

Low electrical efficiency.

The maximum process temperature is limited.

High pump consumption.

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When there are lower and medium sources of temperature and where conventional technologies are not feasible.

Isolated buildings / regions.

Future building integration.

Improve the national energy security.


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TABLE 78: SWOT ANALYSIS OF ORC SYSTEMS – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S


Low maintenance and staffing cost (time required for ORC operation is around three hours per week).

Reusing the waste heat contributes to a reduction in production cost.

Energy savings (covering of own energy demand) and reducing the demand from traditional power generation plants.

Heat recovery systems have the advantage of not incurring fuel costs.

Marketing aspects

Modularity and versatility, as well as the possibility of using it at different temperature ranges, allows the repowering of plants currently in use.

Technology more adapted than steam power to the conversion of renewable energy sources, whose availability is generally more focused on fossil fuels, and whose temperature is lower than traditional fuels.


Positive environmental profile (mitigation of CO2 emissions).

ORC heat recovery systems, allow industrial companies to significantly improve their efficiency while not losing focus on their core activity.

Ecology aspects

Reusing the waste heat contributes to a reduction in deterioration of the environment.

There are no emissions or fuel consumption related to it.


High cost of the working fluid compared to water.

Initial costs are high compared with traditional systems.

Marketing aspects

Limited power ranges from 0.2 – 2 MWel

Difficult to find suitable equipment, mainly the turbine.

Difficult to find the most suitable working fluid. The fluid must have optimum thermodynamic properties at lower temperatures and pressures and must satisfy multiple criteria, such as being economical, nontoxic, non-flammable, environmentally friendly and allows a high use of the energy availability.

There are a few commercial plants.

There are very few ORC plants available in the kW power range, is more developed for the MW power range.

Ecology aspects

Some working fluids are or are being restricted by international agreement depending on their Ozone Depleting Potential (ODP) or on the Greenhouse Warming Potential (GWP).

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Excess energy can be sold to a utility if agreements and protocols can be arranged.


Available incentives for the production of green electricity.


Continuous increase in the number of companies involved in manufacturing these types of machines.

The ORC market is growing rapidly.

The ORC is a mature technology for waste heat recovery, biomass CHP and geothermal power, but still very uncommon for solar applications.

Systems are mainly installed in the MW power range and very few ORC plants exist in the kW power range.

The use of ORC systems creates direct jobs in manufacturing, engineering, installation, ongoing operation and maintenance, and many other areas.

ORC lead to the primary fuel consumption decreasing and therefore, the reduction of imported fuel (making them less fuel import dependent).




Competing against a wide range of contrasted technologies.

End user’s behaviour relates with system’s performance.

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2.3.2. THERMAL COOLING

Responsible Author:



Most heat pumps for cooling applications are mechanically driven. Thermally driven heat

pumps (TDHP) using environmental friendly refrigerants represent an energy efficient

alternative. Their use, in comparison with traditional vapour compression systems, can

create a benefit in terms of reduction of electricity peak load, mitigation of Global Warming

Potential and of primary energy saving, especially when waste heat or solar energy are used

as the driving energy. For these systems, thermal energy is needed to drive the cycle and

electricity is needed only for auxiliary components like pumps to circulate the working fluid.

Thermally driven machines are mainly used for cooling purposes. However, they can also

work as heat pumps with high efficiencies (see Chapter 2.3.4).

TDHP work at three levels of temperature: the machine is driven by a heat source at high

temperature (Th), heat is rejected at medium temperature (Tm) and extracted at low

temperature (Tc). The cold produced at low temperature is the useful effect provided in

chilling mode.

Different types of heat-driven cooling / heat pump systems are available. Liquid absorption

and solid adsorption closed-cycles are the most largely employed. These kind of TDHP are

based on the pairing of a refrigerant and a sorption medium. They use the same

thermodynamic cycle as electrically driven compression heat pumps, where the compressor

is replaced by a thermal sorption cycle. Figure 45 shows the schematics of absorption (a)

and adsorption (b) chillers.

FIGURE 45: SCHEMATICS OF ABSORPTION A) AND ADSORPTION B) CHILLERS (SOURCE: JER)



Absorption heat pump cycle:

As for compression heat pump cycles, in the absorption heat pump a refrigerant is

evaporated at low pressure using a low temperature heat source (useful cooling effect). To

remove refrigerant vapour from the evaporator, a suitable liquid is used absorbing the

vapour and creating a pressure difference that drive the flow of gas. During the absorption

process in the absorber heat is generated and has to be released. After the absorption

phase, the absorbent is diluted and has to be regenerated to maintain its absorption

capability. The diluted solution is therefore pumped to the higher pressure level into the

desorber where heat is supplied to boil off the refrigerant. The vapour refrigerant is

condensed in the condenser, and throttled to the evaporator pressure, so that the refrigerant

cycle can start again. The concentrated solution is also throttled and flows back to the

absorber where it can absorb the vapour refrigerant anew. Another heat exchanger, the so-

called solution heat exchanger, is used to increase the efficiency of the process by internal

heat exchange.

The affinity of the absorbent for the refrigerant enables it to keep the refrigerant in solution

when both evaporator and absorber are at the same pressure but the absorber is at

considerably higher temperature. The most common absorber / refrigerant pairs are: Lithium

Bromide / Water and Ammonia / Water.

Adsorption chillers:

In case of adsorption chillers, the refrigerant is adsorbed in the adsorption bed. This consists

of a heat exchanger and a porous solid medium with a high internal surface area (the

adsorbent). The most common adsorbent / refrigerant pairs are Zeolite / water, Silica

gel / water, activated carbon / ammonia, and activated carbon / methanol. The adsorbent

binds the refrigerant vapour on the surface in the pores and thereby causes the suction

effect. Like for absorption cycles, also during the adsorption process heat is released.

When the adsorbent is loaded up to a certain level it needs to be regenerated. This is

achieved, as in absorption machines, by heating the adsorbent up to a minimum

temperature and driving off the refrigerant vapour to the condenser.

The process of adsorption and desorption works discontinuously. The adsorbent either

adsorbs or desorbs refrigerant vapour. Therefore, usually at least two adsorption beds are

installed operating in opposite phases. During the adsorption phase the adsorption bed must

be connected to the evaporator while during desorption phase the adsorption bed must be

connected to the condenser. This could be controlled by actuated valves.

During the switching between adsorption and desorption, the heat exchanger needs to be

respectively warmed up and cooled down. The cyclic process requires additional heat and

leads to fluctuating outlet temperatures in all hydronic loops. This aspect represents one

weakness of adsorption TDHP with respect to absorption TDHP. To partially mitigate this

problem, an additional operation phase between adsorption and desorption might be

introduced, to reuse the sensible heat of the adsorbent and the heat exchanger.




Ad- and absorption chillers are considered a mature technology, resulting in sales of high

quality products by several manufacturers. Typical applications range from large scale

industrial installations (> 100 kW), down to small scale applications for domestic space

cooling purposes (8 to 50 kW). The low temperature level provided by sorption cooling

machines ranges from -40°C for refrigeration purposes or industrial processes to 6 to 18°C

for air-conditioning (chilled water). Figure 46 shows some typical configurations for TDHP

systems.

FIGURE 46: TYPICAL SOURCES, COLD DISTRIBUTION SYSTEMS AND HEAT REJECTION SINKS FOR A TDHP SYSTEM

(SOURCE: EURAC)

Absorption heat pumps for space heating and cooling are often gas-fired, i.e. are integrated

with a gas boiler that produces the driving thermal energy of the sorption heat pump.

Adsorption machines can be efficiently driven by lower temperatures, making them

interesting for using low temperature waste heat or thermal solar energy. Alternative

solutions include the coupling of TDHP with waste heat from power units or plants for the

cogeneration of electricity, heat and cold from a single fuel source.

In general, the driving heat level required depends on the temperature lift. A high

temperature lift requires a high driving temperature. Temperatures from typical driving heat

sources range from around 55°C (solar cooling) up to 95°C (district heat). Higher driving

temperatures, e.g. from industrial processes or concentrating solar collectors above 120°C

enable more efficient solutions (e.g. double-effect chillers).

Condensation and absorption heat are usually rejected to the ambient air directly or via a

cooling water circuit (dry cooler, wet or hybrid cooling tower) or to the ground (ground

probes, ground collector, ground water). The cooling water temperature range is mainly

between 23 and 40°C but may also be higher.




The performance of TDHP in cooling mode is defined as EER and is the ratio between the

useful cold at low temperature and the driving heat at high temperature.

Besides the EER, two other performance indicators are often used to rate TDHP. The

Seasonal Performance Factor (SPF) is the ratio of the delivered useful energy to the user

divided by the consumed driving energy on the system level. The PER is the ratio of the

useful heating and/or cooling energy in relation to the primary energy demand.

As TDHP systems generally require both thermal and electrical energy for the operation

which are not equivalent in terms of exergy content, price, emissions etc., a clear distinction

between a thermal performance factor and an electrical performance factor should be made,

except for the PER where all energy sources are valued by their primary energy content.

Typical working parameters and EERs for the most common ab- and adsorption chillers

(cooling operation) are reported in Table 79.

TABLE 79: OPERATING PARAMETERS FOR DIFFERENT TYPES OF TDHP FOR COOLING APPLICATIONS [32]

Adsorption Absorption

Refrigerant/ sorbent Water/

Silica gel

Water/

Zeolite

Water/LiBr

Single effect

Water/LiBr

Double effect

Ammonia/

Water

Temperature heat source [°C]

60 – 90 45 – 95 75 – 110 135 – 200 65 – 180

Capacity [kW] 75 – 500 9 – 430 10.5 – 20,000 174 – 6,000 14 – 700

EER 0.5 – 0.7 0.5 – 0.6 0.6 – 0.7 0.9 – 1.3 0.5 – 0.7

TABLE 80: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR THERMAL COOLING


Heat source:

Temperature level

Heat sink:

Temperature level

Outlet temperature

Temperature lift

Electricity, fuel or input heat consumptions

Machine performance curves at rated conditions

(COP as given by the manufacturer)


Machine capacity as function of the temperature



SWOT Analysis of thermal cooling systems for industrial applications

TABLE 81: SWOT ANALYSIS FOR THERMAL COOLING – TECHNICAL ASPECTS


ST

RE

NG

HT

S Need of external electricity input only for

auxiliaries

Compatible with conventional distribution systems

Need of higher drive temperatures to implement double or triple effects configurations

Complex hydraulics and controls for the most efficient configurations

Discontinuous working mode (adsorption chillers) with need of accurate control W

EA

KN

ES

SE

S

OP

PO

RT

UN

ITIE

S

Possibility of coupling with solar thermal systems to be used as drive energy

Increasing employment of RES in industrial processes

Can use waste heat as drive energy (both at low and high temperature levels)

Other technologies for cooling applications typically “more trusted

TH

RE

AT

S

TABLE 82: SWOT ANALYSIS FOR THERMAL COOLING – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S

Marketing aspects

Available also in large sizes (suitable for industrial applications)

State of the art technology: existing installations as best practice

Ecology aspects

Use of environmental friendly refrigerants


High investment costs


Relatively high maintenance cost





Lack of plug-and-play solutions W

EA

KN

ES

SE

S

OP

PO

RT

UN

ITIE

S


Availability of incentive schemes for solar cooling systems

Ecology aspects

Mitigation of electricity peak demand

Reduction of primary energy demand

CO2 reduction policies


Lack of international standard to assess their performance

Large diffusion of compression heat pumps

Lack of awareness among installers and planners T

HR

EA

TS



2.3.3. HEAT EXCHANGER





A heat exchanger is a piece of equipment built for efficient heat transfer from one medium

to another. For efficiency, heat exchangers are designed to maximize the surface area of

the wall between the two fluids, while minimizing resistance to fluid flow through the

exchanger.

There are four primary classifications of heat exchangers according to their flow

arrangement. In parallel-flow heat exchangers, the two fluids enter the exchanger at the

same end, and travel in parallel to one another to the other side. In counter-flow heat

exchangers the fluids enter the exchanger from opposite ends. The counter current design

is the most efficient, in that it can transfer the most heat from the heat (transfer) medium due

to the fact that the average temperature difference along any unit length is greater.

This procedure is not limited to only fluids it’s also possible mediums air or steam. But the

medium air does not make sense for process heat, because the temperatures are too low.

This technology can be used for heat recovery in the processes. It uses the excess (waste)

heat from the process with the upper temperature level to heat another process with lower

temperatures. So this heat does not have to produce new again.

This heat recovery can also be used for other technologies (like for sorption chillers etc.;

described in Chapter 2.3.2) to get eventually cold water.

FIGURE 47: FUNCTIONAL PRINCIPLE OF A HEAT EXCHANGER (SOURCE: JER)




Each manufacturing has different waste heat sources at temperature levels from 100 up to

1,000°C and above, which can be used for further processes.

So, for example: at the food industry the waste heat from the baking process (ca. 200°C)

could use for another process like drying (ca. 130°C). In the textile processing the heat from

sizing can be used for the dying processes. And in the industry of steal there are high

temperatures between 400 and 800°C. Therefore, a heat exchanger could save a lot of

energy because it does not have to be heated again.


TABLE 83: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR HEAT EXCHANGER SYSTEMS


Waste heat Heat for other processes Heat transfer depending on heat exchanger type and geometry



SWOT Analysis of Heat exchanger systems for industrial applications

TABLE 84: SWOT ANALYSIS FOR HEAT EXCHANGERS – TECHNICAL ASPECTS


ST

RE

NG

HT

S High COP achievable

Easy to install

Can be modular in terms of capacities

Can be custom-sized according to the specific application

Can be coupled with existing heating and cooling distribution networks

If it’s not a continuous process, coupled to the main process

Other smaller process or other source (heat, cold, etc.) is required

Reconstruction work at the network have to be performed

Old system may be unnecessary WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S

Currently a lot of research in the efficient sector, therefore higher potential of efficiency expected

Not suitable for all kind of applications (e.g. low temperatures waste heat recovery inappropriate)

TH

RE

AT

S

TABLE 85: SWOT ANALYSIS FOR HEAT EXCHANGERS – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S

Cost and Market related parameters

Short ROI times in industrial applications compared to other RES

Ecology aspects

Positive environmental profile – mitigation of additional CO2 emissions

Waste heat recovery


Maintenance cost required

Ecology aspects

An energy-efficient measure, but not a renewable energy source


Less published technology

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S




By public notice higher level of recognition


Although known but not often used

Lack of awareness among installers and planners

TH

RE

AT

S



2.3.4. HEAT PUMP

Responsible Author:



Heat pumps are employed for both heating and cooling purposes to transfer heat from a

heat source at a low temperature to a heat sink at a higher temperature through evaporation

and condensation cycles of a working fluid. To achieve this, an external drive energy is

needed, which can be either electricity (electrically driven heat pumps), fuel or high

temperature heat (thermally driven heat pumps). Heat pumps can also be classified

according to the medium from which they extract energy (i.e. air, water, ground or waste

heat), the heat transfer fluid they use (air or water) and their purpose (cooling, space heating

and water heating).

FIGURE 48: ELECTRIC MOTOR-DRIVEN VAPOUR COMPRESSION HEAT PUMP (SOURCE: JER)

The majority of existing heat pumps are electrically driven systems employing a vapour

compression cycle, schematically represented in Figure 48. The simplest circuit for a vapour

compression heat pump consists of a condenser, an expansion device, an evaporator and

a compressor. The refrigerant (at low pressure) passes through a heat exchanger

(evaporator) and absorbs heat from the low-temperature source. The refrigerant evaporates

into a gas as heat is absorbed (phase 1 in Figure 48). The gaseous refrigerant then passes



through a compressor where it is pressurized, raising its temperature (phase 2 in Figure 48).

The hot gas then circulates through a condenser where the heat is removed to the heat sink.

As the refrigerant rejects heat, it changes phase back to liquid phase (phase 3 in Figure 48).

The liquid refrigerant at high pressure exits the condenser and passes through an expansion

device, which reduces the pressure of the refrigerant, bringing it to its starting point (phase

4 in Figure 48).

Even though electric heat pumps are the most largely employed, other kind of heat pumps are

available. Engine driven heat pumps are also based on the vapour compression cycle of a

process fluid, but the compressor is driven by a gas or diesel engine. Heat from the cooling

water and exhaust gas of the engine is used in addition to the condenser heat (Figure 49-a).

Thermally driven he at pumps use the same thermodynamic cycle as electrically driven

compression heat pumps, but the compressor is replaced by a thermal sorption closed-cycle

(Figure 49-b). Electric input is only needed for the circulation pump and the control devices.

Thermally driven heat pumps are mainly used for cooling in combination with waste heat or heat

from renewable sources e.g. solar (see Chapter 2.3.2). However, they can also produce large

quantities of medium temperature heat with high efficiencies.

Thermally driven heat pumps for heating applications can be divided into two sub-categories.

“Type I” heat pump can use a lower and a higher temperature heat input to reject heat at an

intermediate level (e.g., upgrade the low temperature heat). A “Type II” heat pump (also called

thermally driven heat transformer) can use a medium temperature input to reject heat in one

lower temperature stream and one higher temperature stream.

Different working fluids can be used to run heat pumps. Chlorofluorocarbons (CFCs) have

been largely employed in the past but, due to their global environment damage potential,

are currently being replaced by Hydrochlorofluorocarbons (HCFCs), Hydrofluorocarbons

(HFCs) and natural working fluids (such as ammonia, water, hydrocarbons and CO2).

FIGURE 49: A) ELECTRICAL DRIVEN HEAT PUMP; B) ABSORPTION HEAT PUMP (SOURCE: JER)




Heat pumps can cover a broad range of applications, although the largest market share is

currently still represented by heating and cooling of residential buildings (residential

applications represents nearly 90% of the heat pump market, with average capacity installed

lower than 20 kW [33]. A very promising area for the application of heat pump systems,

where a market growth is expected, is represented by industrial processes where large

amounts of waste heat at relatively low temperatures are available. Large (> 100 kW) heat

pumps could be employed in these cases both to “upgrade” the low temperature heat or for

cooling purposes. Heat pumps to be installed in industrial processes are usually custom-

made, meaning that each component of the unit is sized according to the specific needs of

the application. Typical industrial applications, suitable for the employment of heat pumps

include:

Space heating

Heating and cooling of process streams (T = 40 – 90°C)

Water heating for washing, sanitation and cleaning

Steam production (T = 100 – 200°C)

Drying / dehumidification (T < 100°C)

Evaporation

Distillation

Concentration

The most commonly employed heat pumps for industrial waste heat recovery are

Mechanical vapor recompression systems (MVRs) where the process fluid itself is used as

working fluid in an open cycle. Typical working conditions include source temperatures of

70 – 80°C and deliver temperatures up to 110 – 150°C (in some cases up to 200°C).

Traditional absorption heat pumps are not largely employed in industrial applications; some

examples can be found with output temperatures in the range of 100°C and temperature lifts

of about 65°C. New generation absorption heat pumps, however, presents some key

features which could make them suitable for industrial purposes: they can deliver a much

higher temperature lift than compression systems (> 100°C) and their energy performance

does not decline steeply at higher temperature lifts. Moreover, they can be customized for

combined heating and cooling applications.

The final economical sustainability of installing heat pumps for waste heat recovery

purposes, as well as the final temperature lift achievable strongly depends on the kind of

installed systems, on the temperature level at which waste heat is available and on the

working fluid employed in the heat pump thermodynamic cycle.


The steady-state performance of a heat pump at a given set of temperature conditions is

referred to as the COP. It is defined as the ratio of heat delivered by the heat pump and the

driving power supplied to the unit. The COP relative to the cooling capacity is usually called

EER. Depending on whether electricity or heat is considered as driving energy, an electrical

or thermal COP can be calculated. Another largely employed performance figure is the

Primary Energy Ratio (PER), defined as the ratio of the useful energy output to the primary



energy input to the system boundary. To evaluate the system under real operating condition

it is useful to consider the SPF, defined as the useful energy output to the overall useful

energy input to the system within the respective boundary. The SPF may vary considerably

depending on the system boundary conditions considered for the energy evaluation.

The COP (or EER) strictly depends on the type of heat pump considered, and on the

operating conditions of the unit, particularly on the employed heat source and on

temperature lift obtained on the process fluid. Typical COP for heat pumps working with a

vapour compression cycle range between 3 and 5 (although heat pumps with higher COP

are available). Heat pumps working with an absorption cycle reach COPs of about 1.6 – 1.8.

MVR systems in industrial applications, where one or two heat exchangers might be

eliminated and where normally limited temperature lofts are required, might reach COPs

between 10 and 30. Table 86 summarizes some characteristic parameters of different heat

pumps.

TABLE 86: OPERATING PARAMETERS FOR DIFFERENT TYPES OF HEAT PUMPS

Heat Pump type Max. Sink Temp.

Max Temp. Lift

COP ranges

Electrical Motor Closed Compression Cycle 120°C 80°C 3 – 8

Diesel Motor Closed Compression Cycle 130°C 90°C 1 – 2

Mechanical Vapour Recompression 190°C 90°C 10 – 30

Absorption Cycle (Type I, Heat Pump) 100°C 65°C 1.0 – 1.8

Absorption Cycle (Type II, Heat Transformer) 150°C 50°C 0.45 – 0.48

A major barrier to the spread of heat pumps market is represented by the high initial

investments required. As a reference, in Table 87 the typical installation costs for three

common types of residential heating and cooling heat pumps are showed. Data for the

industrial sector are difficult to summarize since most heat pumps for process heat are

custom designed. As an order of magnitude, the typical installation costs of an heat pump

for industrial waste heat recovery and steam production range between 200 – 300 €/kW.

TABLE 87: TECHNOLOGY AND TYPICAL COSTS OF HEAT PUMPS FOR RESIDENTIAL SPACE HEATING, COOLING AND HOT

WATER SUPPLY OF SINGLE-FAMILY HOUSES [34]

OECD Europe North America

China & India OECD Pacific

Typical size (kW) 2 – 15 2 –19 2 – 4 2 – 10

Co

st

(€/k

W) Air-to air 424 – 1,087 274 – 475 137 – 171 304 – 407

Air to water 461 – 2,422 361 – 494 228 – 304 426 – 1,013

Geothermal 889 – 1,723 380 – 646 334 – 456 760 – 3,040

To partially overcome these barriers, many countries promotes policy measures to sustain

the use of heat pumps in the form of subsidies and grants.

The ROI for heat pumps largely depends on the kind and size of machine installed, on the

average number of hours in which the heat pump is run and on the existence of particular

subsides or tariffs in the considered country. Typical ROIs for residential installations range



between 3 – 5 years. For industrial applications with continuous processes, ROIs of 2 years

can be reached, again depending on the location and the kind of heat pump installed.

TABLE 88: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR HEAT PUMPS


Heat source:

Temperature level

Heat sink:

Temperature level

Drive energy type

(e.g. electricity, fuel, heat)

Outlet temperature

Temperature lift

Electricity, fuel or input heat consumptions

HP performance at rated conditions

(COP as given by the manufacturer)


HP capacity as function of the temperature

SWOT Analysis of heat pump systems for industrial applications

TABLE 89: SWOT ANALYSIS FOR HEAT PUMPS – TECHNICAL ASPECTS


ST

RE

NG

HT

S

High COP achievable and high potential for further increase

Can be modular in terms of capacities

Broad range of applications available

Can be custom-sized according to the specific application

Can be coupled with existing heating and cooling distribution networks

Primary energy efficiency dependent on the electricity production efficiency (or on the thermal energy source)

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S

Can be used for waste heat recovery both at low (0 – 95°C) and at medium (96 – 250°C) temperatures

Can be employed in industrial processes with continuous waste heat availability

Can be coupled to processes with relatively small temperature lifts required

Bridge technology between electricity and thermal smart grids

Possibility to be coupled with other RES systems (e.g. PV to cover the electrical consumptions of the compressor)


Not suitable for all kind of applications (e.g. high temperatures waste heat recovery)


TH

RE

AT

S



TABLE 90: SWOT ANALYSIS FOR HEAT PUMPS – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S


Short ROI times in industrial applications compared to other RES

Ecology aspects



The employment in industrial environments characterized by non-continuous operation might result in an economical non-sustainability of heat pump systems

High initial investments required

Maintenance cost required

Ecology aspects

Environmental threats if CFCs are employed as working fluid

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S



Available financial incentives schemes per country






Ecology aspect

CO2 reduction policies in industries


No financial incentives or reduction of the existing financial incentives, ceasing the technology being attractive (E.g. Spain)

Financial incentives for other type of technologies (E.g. Spain)

Legislation of the country supporting fossil fuels technologies (E.g. Spain)

Regulatory uncertainty (E.g. Spain)



Lack of awareness among installers and planners


TH

RE

AT

S



2.3.5. WHP SYSTEM (PRESSURE REDUCTION)





Waste thermal energy is one of the largest sources in the industry of inexpensive free

energy. Industrial processes that involve transforming raw materials into useful products

have often waste heat as a by-product, which is produced whenever the operation is

running, often 24 hours a day, seven days a week. As part of the energy supply for

productions steam networks are often used in manufacturing processes.

In such steam networks high vapour pressure is usually generated, which is then reduced

prior to the consumer according to the requirements. High pressures are advantageous for

the transportation of steam, because it allows smaller pipe diameters. A pressure reduction

is achieved by pressure drop during flow through a constricted flow area. Here, a throttled

shut-off valve can achieve the simplest form of pressure reduction. However, a change in

the throughput will also lead to a deviation of the downstream pressure. In a pressure-

reducing valve, the valve automatically adjusts the flow cross-section, so that the

downstream pressure remains constant even with fluctuations in the throughput.

An energy-efficient alternative is the use of so-called Waste Heat to Power (WHP) systems.

There are two different kinds of WHP systems for the pressure reduction in steam networks

available. The first system occurs in classical pressure reduction systems where the

enthalpy gradient is not often used. On the contrary the previously expensive generated

steam is often cooled by additional, expensive energy again. By integration of a WHP

system into existing steam networks additional electrical energy can be generated. The

cogeneration system uses the pressure drop and boiler potential in order to generate

electrical energy based on a screw expander. This system optimizes the energy efficiency

of the steam process. The available electrical power range is from 35 up to 400 kWel per

module.

FIGURE 50: MARKET AVAILABLE WHP SYSTEMS (SOURCE: ERGION)



The second WHP system allows the use of additional energy from different waste heat

sources e.g. pressurized hot water, thermal oil or steam from fuel, biogas or biomass boilers

at a temperature level of 170°C. Therefore, an internal heat exchanger is used, which

removes the heat transfer medium energy and thus cools the medium. In the case of steam

this is condensed. The outlet temperature of the additional thermal energy input is then

between 80 to 105°C, which can then be used for further processes. This WHP system will

be installed in parallel to an existing steam cycle, which then uses the waste energy from

production process or exhaust gases and the energy of the pressure drop in the primary

steam network to produce electricity using again a screw expander. In conjunction with CHP

engines this WHP system process increases the electrical output up to about 10% by

otherwise unused thermal energy. The available power range is from 30 up to 400 kWel.


WHP systems help to reduce energy costs for industrial processes. By using the enthalpy

gradient of steam pressure reduction and additional waste heat to generate emission-free

electricity, industrial users can put wasted energy back into the process that created it, route

the power somewhere else in the facility, or sell it to the grid to support clean energy

production, distribution and use. WHP systems are easy to integrate in conventional steam

networks through precise and fully automatic control. Furthermore, WHP systems can be

used either as pressure reducer and/or condensation routes.

FIGURE 51: SCHEME OF A WHP SYSTEM ONLY FOR PRESSURE REDUCTION (SOURCE: JER)



FIGURE 52: SCHEME OF A WHP SYSTEM INCLUDING ADDITIONAL WASTE HEAT INPUT (SOURCE: JER)


TABLE 91: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR WHP SYSTEMS


Steam

Additional pressurized hot water, thermo oil or steam at temperature level of 170°C

Electricity

Additional thermal energy at a temperature level of 80 – 105°C

Electrical efficiency of 5 – 15%

SWOT Analysis of WHP systems for industrial applications

TABLE 92: SWOT ANALYSIS FOR WHP SYSTEMS – TECHNICAL ASPECTS


ST

RE

NG

HT

S

Relatively simple technology


Robust low-maintenance screw expander



Compatibility with conventional steam networks

Highly integrative through precise and fully automatic control

Versatile use as a pressure reducer and/or condensation routes

No storage required

Installation only possible if production process is stopped

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S




TH

RE

AT

S



TABLE 93: SWOT ANALYSIS FOR WHP SYSTEMS – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S


No expensive turbine technology

Negligible operating cost









WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S






Global market for WHP systems, related technologies and support service

Several possible applications in industrial sectors where steam networks are used

The waste heat of some processes could be applied to the WHP system (which can be an additional input for the electricity conversion from thermal energy).





TH

RE

AT

S



2.4. ENERGY EFFICIENT HYBRID SYSTEMS

2.4.1. COMBINED HEAT AND POWER (NATURAL GAS)







CHP plants (also named cogeneration), produce electricity and useful heat from different

energy sources, in this case natural gas or oil. It represents a highly efficient method of

generating energy [12, 17 – 23].


















cogeneration.







plants.

Here, natural gas / oil is used to run an engine or turbine, which in turn drives an alternator

to produce electricity. This process also generates heat, the CHP process emphasizes

capturing it through generation by-products such as steam and hot water, which can then

be used for things like industrial processes or space heating.



CHP through gas turbines

In this technology, air is taken in, compressed, burned with a fuel (usually natural gas), and

then ejected to drive a turbine that generates power. Heat can be recovered from the

exhaust and put to use for heating, cooling (through an absorption machine), or industrial

processes.

CHP through gas / oil engine

The engines have a combustion chamber in which fuel is burned. The combustion pushes

a piston that drives a crankshaft to generate power. Heat can be recovered from the exhaust

and jacket water and put to use for heating, cooling, or industrial processes.

CHP through steam turbines

In these turbines, water is pressurized, heated by a burning fuel, and converted to steam,

which is then used to drive a turbine that generates power. Any exhaust steam left after the

power-generation step can be put to productive use for heating, cooling, or industrial

processes.

CHP projects are appealing to the industry, as they reduce energy bills and carbon

emissions, and allow them to generate their power independently.


The majority of today’s large industrial and commercial CHP applications are in the pulp and

paper, chemical, refining, food processing, ethanol and manufacturing sectors, which

require vast amounts of electricity and heat, and typically run on natural gas.

Figure 54 shows general schemes of CHP systems through steam and gas turbines, and

gas / oil engine.

FIGURE 53: SCHEME OF CHP SYSTEMS INTEGRATED TO INDUSTRY. GAS TURBINES OR GAS/OIL ENGINE (SOURCE: IESO)



FIGURE 54: SCHEMES OF CHP SYSTEMS INTEGRATED TO INDUSTRY. THROUGH STEAM TURBINES (SOURCE: IESO)









90% of the fuel’s potential energy into useful energy.

In the following table, the different technologies that can be used to produce energy based

on natural gas / oil CHP systems are shown. Depending the needs of the industry in which

is going to be installed this technology; one or another will be more suitable (thermal and

electrical needs, budget available, operation hours, fuel, etc.).



TABLE 94: MAIN PARAMETERS ACCORDING TO POWER GENERATION TECHNOLOGY THAT USE FOSSIL FUELS IN CHP

SYSTEMS

Diesel Engine

Natural Gas Engine

Steam Turbine

Gas Turbine Micro-turbine

Electric Efficiency (LHV)

30 – 50% 25 – 45% 30 – 42% 25 – 40% (simple)

40 – 60% (combined)

20 – 30%

Size (MWel.) 0.05 – 5 0.05 – 5 Any 3 – 200 0.025 – 0.25

Footprint (m2/kW) 0.02 0.02 – 0.03 < 0.01 0.002 – 0.057 0.014 – 0.14

CHP installed cost (€/kW)

600 – 1,100 600 – 1,100 600 – 730 510 – 650 365 – 950

O&M Cost (€/kWh) 0.0036 – 0.0058 0.0051 – 0.011 0.0029 0.0015 – 0.0058 0.0015 – 0.0073

Availability 90 – 95% 92 – 97% Near 100% 90 – 98% 90 – 98%

Hours between overhauls

25,000 – 3,000 24,000 – 60,000 > 50,000 30,000 – 50,000 5,000 – 40,000

Start-up Time 10 s 10 s 1 h – 1 day 10 min – 1 h 60 s

Fuel pressure (bar) < 0.34 0.069 – 3.1 n/a 8.27 – 34.47 (may require compressor)

2.76 – 6.89 (may require compressor)

Fuels Oil Natural gas Oil

Natural gas

Natural gas Natural gas

Noise Moderate to high (requires

building enclosure)

Moderate to high (requires

building enclosure)

Moderate to high (requires

building enclosure)

Moderate (enclosure

supplied with unit)

Moderate (enclosure

supplied with unit)

NOx Emissions (kg/MWh)

1.36 – 15 1 – 12.7 0.816 0.136 – 1.8 0.181 – 1

Uses for heat recovery

Hot water

LP steam

District heating

Hot water

LP steam

District heating

LP steam

HP steam

District Heating

Direct heat

Hot water

LP steam

HP steam

District heating

Direct heat

Hot water

LP steam

CHP Output (kWhth./kWhel.)

1 0.29 – 1.46 n/a 1 – 3.5 1.17 – 4.4

Useable Temp (°C) 80 – 480 150 – 260 n/a 260 – 600 200 – 340

TABLE 95: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR CHP SYSTEMS


Natural gas (Fuel)

Oil (Fuel)

Water (to produce steam and/or hot water)

Air for combustion

Electricity

Heat (Steam, hot water)

Cold through a thermal cooling machine

Exhaust gases

Global efficiency: 75 – 90%

Electrical efficiency: 30 – 35%

Thermal efficiency: 45 – 50%

Capacity range from 25 – 250 MWel

Estimated costs per installed kW range from 350 – 1,100 €/kW



SWOT Analysis of natural gas or oil fired CHP systems for industrial applications

TABLE 96: SWOT ANALYSIS FOR GAS AND OIL CHP UNITS – TECHNICAL ASPECTS


ST

RE

NG

HT

S

Fast start-up which allows timely resumption of the system e.g., after a maintenance procedure.

CHP systems that use fossil fuels have demonstrated availability in excess of 90%.

Gas-fired cogeneration plants are technologically and economically proven.

Good part load operation.

Reliable and long life: CHP systems that use fossil fuels have provided many years of satisfactory service given proper maintenance.

Quality thermal output: CHP systems produce a relative good quality thermal output suitable for most applications.


Thermodynamic efficient use of fuel. Conventional power generation discards up to 65% of energy potential as waste heat, while CHP plants have a global conversion efficiency of 75 – 90 %.


Proximity of the average cogeneration facility, compared to the 5 – 10% loss in transmission of electricity from typically remote traditional power stations.


CHP systems are typically scalable according to a facility’s electrical and thermal needs. It have a capacity range from 25 – 250 MWel

High energy content per volume

Require a very secure storage system because fuel source (natural gas / oil) is highly flammable and therefore can be dangerous if not properly maintained.

It could be necessary instead of the storage system for the natural gas, a connection point to the natural gas network.

Require large infrastructures and / or logistics aspects for the transport and distribution of these kinds of fuel sources.

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ITIE

S Continued availability of CHP systems is crucial, due to

its high efficiency.

In peaking or emergency power applications, CHP systems can quickly supply electricity on demand

Advances in electronics, controls and remote monitoring capability should increase the reliability and availability. Maintenance intervals are being extended through development of longer life spark plugs, improved air and fuel filters, synthetic lubricating oil, etc.

Compete against a wide range of emerging technologies. E.g., those that using renewable energies as fuel.

TH

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TABLE 97: SWOT ANALYSIS FOR GAS AND OIL CHP UNITS – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S

Cost related parameters:

Good cost effectiveness: Estimated costs per installed kW range from 350 – 1,100 €/kW.

Primary energy savings and therefore, production cost, compared with two generation systems that produce electricity and heat separately for covering own energy demand.

Reducing operating costs and downtime, compared to the renewable technologies which require a more complex operation and maintenance.

By generating on-site power and thermal energy, it is possible to displace as much as one-third to one-half of the overall energy expenditures at a facility, especially in regions where purchased power from utilities is relatively expensive.

Natural gas is one of the cheapest fuels used today.

Marketing aspects

Economical size range: CHP using fuel fossils are available in sizes that match the electric demand of many end-users (institutional, commercial and industrial).

Positive environmental profile - mitigation of CO2 due to decreased energy primary.

Power generation technology that use fossil fuels in CHP systems have been commercially available for decades (has a large and historical market.). A global network of manufacturers, dealers and distributors is well established.

Environmental

CHP reduces greenhouse gas emissions compare to other technologies.


Use of fossil fuels for CHP systems in some countries of EU causes an energetic dependence.

Price of fossil fuels for use in CHP systems is increasing and/or is volatile.

Supply chain for fossil fuel for use in CHP systems is characterized by long transport distances.

Marketing aspects

CHP systems use fossil fuels which are controlled by a few international companies.

Regulation of some countries restricts the auto-consumption.

Requires building enclosure because have from moderate to high noise levels.

Environmental

Use of fossil fuels in CHP systems contributes to global warming through greenhouse gas emissions, in addition to emit environmental contaminants as particles and sulphur oxides.

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CHP systems can also provide saleable steam and heat to other industry or nearby buildings.

Energy bill savings and additional revenue streams (e.g.: clean energy credits) provided by CHP systems can be reinvested in facilities (or companies at large) to support facility expansion and other capital projects, leading to an increase in competitiveness.




The use of CHP systems creates direct jobs in manufacturing, engineering, installation, ongoing operation and maintenance, and many other areas.

There is tremendous potential for greater deployment of CHP in industrial and large commercial/institutional applications.


CHP has strong dependence on fossil fuel prices (not particularly stable).

Natural gas and oil are a finite resource and as a result will not be a completely long term solution as more usage such as CHP will drive up costs.

Decrease in the price of other fuels and/or maturity of others technologies.


The use of renewable energies such as biomass.

Fossil fuel production is limited due to the limited availability of crude oil.

The market share of fossil fuels will decrease.

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2.4.2. COMBINED HEAT AND POWER (FUEL CELL)

Responsible Author:

Diego Bartolomé: CRIT, Vignola, Italy


A Fuel Cell CHP system generates both heat and electric power from an electrochemical

source, which consists of a reduction-oxidation (redox) reaction. Unlike classic CHP

systems, driven with fossil fuel combustion, CHP Fuel Cells (CHPFC) do not rely on a

thermodynamic Carnot cycle. On the contrary, they are closely related to electrochemical

batteries, because the operating principle is the same, having an anode and a cathode

connected by the electrolyte. Disparate to batteries, fuel cells can provide uninterrupted

energy as long as they are continuously supplied with fuel at the accurate temperature

through the porous cathode and anode. CHP fuel cells are typically driven with hydrogen

and oxygen to obtain water and direct electric current (DC). The diverse characteristic

reactions of CHPFC are shown in the Table 98 below.

TABLE 98: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR CHP SYSTEMS

Technology PAFC MCFC SOFC

Anode reaction

2H2 → 4H+ + 4e– 2CO3 2– + 2H2 → 2H2 O + 2CO2 4e– H2 + O2– → H2 O + 2e–

CO + O2– → CO2 + 2e–

Cathode reaction

O2 + 4H+ 4e– → 2H2 O 2CO2 + O2 + 4e– → 2CO3 2– O2 + 4e– → 2O2–

Overall reaction

2H2 + O2 → 2H2 O 2H2 + O2 → 2H2 O H2 + CO + O2 → H2O + CO2

The exothermic overall reaction liberates a lot of thermal energy. Unlike Polymer Electrolyte

Membrane or Proton Exchange Membrane (PEM) and Alkaline Fuel Cells, which operate at

temperatures close but below 100°C, CHP fuel cells operate at high temperatures. The three

technologies used for CHP are Phosphoric Acid Fuel Cells (PAFC), Solid Oxide Fuel Cells

(SOFC) and Molten Carbonate Fuel Cells (MCFC). All of them generate water vapour that

can be used for: space heating, water heating, and relatively low-temperature process

needs. PAFC operate normally at 150 – 200°C and low steam pressures but SOFC and

MCFC, working at 600 – 1,000°C and mid-pressure steam, may propel a Rankine Cycle

electric generator to obtain greater electrical efficiencies. CHPFC are characterized with

electrical efficiency, ranging 40 – 60%, and overall efficiency (electrical + thermal), 70 –

90%, depending on the technology used. Further output parameters are gas characteristics

(temperature, pressure, flow), which are significant to determine ancillary processes

(Rankine Cycle, heating, etc.).

For low-temperature fuel cells a Steam Reformer is normally used to obtain hydrogen

(gaseous) from natural gas (NG). On the other hand, SOFC and MCFC are capable of

carrying out an internal reforming process in the fuel cell, so they may operate directly with

NG, biogas, coal-bed methane or ‘syngas’. Fuel Cells, mounted on series configuration so

higher voltages are reached, require the installation of a power inverter, to switch from DC

to AC current at the grid voltage and frequency.



FIGURE 55: PEM TECHNOLOGY SCHEME FOR CHP (SOURCE: JER)


Fuel cells are closely related with the ‘Hydrogen Economy’, so important advances in this

way must happen before this hybrid alternative is considered a mainstream solution instead

of the promising opportunity that represents nowadays. Moreover, this technology is in

continuous development to improve its current performance and price competitiveness

compared to other energy efficient systems. Because of it, the current status of CHP Fuel

Cells is more R&D oriented SOFC, than commercially oriented PAFC and MCFC.

Anyway, if this technology is applied, its integration will have two different orientations. On

the one hand, it can represent an energy storage solution for RES by carrying out electrolysis

of water in a Distributed Generation environment. On the other hand, this energy efficient

system will generate electricity for the manufacturing plant needs, and the residual heat

should be adapted to be used with different on-site purposes: space heating, hot water,

steam production, etc., so the overall efficiency (thermal + electrical) is maximized. The

thermal applications will vary depending on the Fuel Cell (FC) technology used, because of

the different operating temperature ranges.



FIGURE 56: GENERAL CHP FUEL CELL SYSTEM (SOURCE: ENERGY SOLUTION CENTER)


Fuel cells are typically characterised with its electrical efficiency (ηel) and output electric

power (measured in kW), the highest quality energy that they provide. Furthermore, in CHP

systems it is of vital importance the overall efficiency (ηT), that may justify the adoption of a

hybrid system. Speaking about economic performance, current CHPFC technologies are

still very expensive compared to other CHP technologies. However, prices keep a sustained

downhill tendency that could allow this technology to become affordable in the future. The

principal indicators of two commercial CHP Fuel Cell solutions are shown below:

TABLE 99: COMMERCIAL PAFC [35] AND MCFC SOLUTIONS [36]

Type of CHP FC PAFC MCFC

Provider Clear Edge Fuel Cell Energy Solutions

Energy characteristics

Output Electric Power (kW) 400 2,800

Electrical efficiency – HHV 38% (42% - LHV) 42% (47% - LHV)

Output Thermal Power at high temp (kW) 188 (at 120°C) 1,298 (at 120°C)

Output Thermal Power at low temp (kW) 258 (at 60°C) 2,184 (at 50°C)

Overall average efficiency - HHV* 57% 62%

Fuel used Natural gas Natural gas

Fuel consumption (Nm³/h) 94.2 614

Costs

Total installation costs ($/kW)* 6,460 5,600

Variable O&M costs ($/kWhel)* 0.02 0.02

Fixed O&M costs ($/kWel year)* 300 300

*Last available data: 2010



The continuous development of this technology will improve both the energy and economic

performance. According to the Department of energy (DoE) Hydrogen and Fuel Cells

Program Record (USA, year 2012), it is foreseen to reach up to 90% overall efficiency (LHV)

and over 50% electrical efficiency for mid / long-scale commercial applications. Furthermore,

life expectancy should double, as well as increase system availability from the current 95%

to figures around 99%. On the other hand, total cost installations are expected to cut down

to one half of the current costs.

TABLE 100: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR FUEL CELL CHP SYSTEMS


Anode fuel:

Hydrogen, natural gas, syngas, etc.

Cathode gases:

Oxygen, carbon dioxide (depending on FC used)

Electrical voltage (V), current (A) and power (kW)

Excess fuel (hydrogen and unused air)

Recirculated CO2 (MOFC)

Water Steam (Thermal energy in kW at a determined temperature)

State variable (T,p), composition (%), and flows(Nm³/h) of anode & cathode input / output

Output Voltage (VDC)

Electrical efficiency and power (ηel, E)

Thermal efficiency and power (ηth, Q)

Overall efficiency (ηT = ηel + ηth = ET

∆G )

Working temperature

Sulphur, CO & other present impurities (%)

SWOT Analysis of fuel cell CHP systems for industrial applications

TABLE 101: SWOT ANALYSIS FOR FUEL CELL CHP UNITS – TECHNICAL ASPECTS


ST

RE

NG

HT

S

No Carnot cycle thermodynamic limitations

No rotating parts

Overall efficient process (70 – 90%)

Higher electrical efficiency, up to 60%, compared to conventional CHP

Clean and quiet process

Much better efficiency working at partial loads than conventional CHP

High quality heat, steam temperature > 200°C no Carnot cycle thermodynamic limitations

No rotating parts

Overall efficient process (70 – 90%)

Higher electrical efficiency, up to 60%, compared to conventional CHP

Clean and quiet process

Much better efficiency working at partial loads than conventional CHP

High quality heat, steam temperature > 200°C

Low energy density compared to oil, coal

Complex system

High working temperatures

Great temperature gap with most industrial processes

Slow ramping up and down (approx. half an hour)

Thermal stress and corrosion reduce fuel cell life

Complex Installations: Power inverter required, hydrogen storage may be necessary

Hydrogen associated risk prevention needs: freeze burns, fire and explosion

Low durability

Uncertain reliability

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More efficient, simpler and smaller devices can be designed and built with more R&D funding

Renewable Energy Sources (wind farms and solar PV) integration through electrolysis-based H2 production

Biomass gasification into biogas to propel high temperature CHPFC

Lately Biological (Algae) hydrogen production research could represent a boost of the H2 and fuel cell economy

Cupola combustion flue gases temperature share temperature range with SOFC & MCFC for fuel preheating

Increase of manufacturing plant energy efficiency

Foster innovative materials research

More convenient Li-ion battery electrical storage efficiency (80 – 90%) outshines fuel cells for mid-scale installations

Pumped hydro storage efficiency (70 – 80%), as great-scale electrical storage, is not reachable

Short maintenance and overhaul time intervals than other utilities may not be sufficiently improved

Lack of current support infrastructure

Great technology competence in the Asian market (Japan & S. Korea mainly) and USA

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TABLE 102: SWOT ANALYSIS FOR FUEL CELL CHP UNITS – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S


More convenient materials are used compared to low temperature fuel cells

80% approximate price drop since 2002, and 35% since 2008, according to the US Government.

Marketing aspects

Positive environmental profile – Economy of Hydrogen

State of the art equipment (MCFC, SOFC) in continuous development

Existing installations considered as best available techniques (mainly in Japan, S. Korea and USA)


High capital cost

High installation costs

High maintenance cost

High operating cost

Marketing aspects

High % of hydrogen comes from fossil fuels (natural gas and coal)

Non-adequately trained technical personnel in the EU-28

Small or practically neglect commercial market in the EU-28

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Unceasing fast price drop rate

National governmental loans, incentives and deductions in diverse countries

EU funding. Horizon 2020 framework programme.

Marketing aspects

Foster energy independence

Reduction of CO2 emissions by Renewable Energy Sources integration

Develop the “Hydrogen economy”: great number of mid-skilled and high-skilled jobs


Yet a too high investment for Small and Medium Enterprises (SME)

Marketing aspects

General belief of hydrogen as a dangerous technology: flammable and even explosive

Currently, the hydrogen economy is not a liable CO2 emissions reducer as H2 it is mainly obtained from CH4 reforming

(CH_4+H_2 O→CO+〖3H〗_2) at high

temperatures (700 – 1,000°C)

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2.4.3. CHPC (COMBINED HEAT POWER AND COLD)





CHPC is a combined system, which consists of a CHP (natural gas / oil, fuel cell, biogas or

wood pellets / chips) to produce electricity and heat (tri-generation system). In the

combination with a thermally driven sorption chiller (absorption or absorption chiller) the

waste heat of the CHP can be used to produce cold water for cooling applications.

FIGURE 57: SYSTEM SCHEME OF A CHPC SYSTEM (SOURCE: JER)

Generally, one differentiates between electricity and heating energy driven CHP systems.

For economic reasons the combined energy production is mostly heating energy demand

driven (temperatures 90 – 110°C). This means, a CHPC is operated, if heat is needed or

wanted to be produced for either heating applications or to run the sorption chiller to provide

cooling energy for e.g. process cooling and air-conditioning of factory spaces or office

buildings etc. The produced electricity is either used directly in the factory / building of the

CHPC or fed into the national grid. A CHPC with the main aim to produce electricity is

operated independently of the actual heating energy demand. Surplus waste heat in summer

months is released to the environment by air coolers if not needed. The application of a

sorption chiller offers the opportunity to use at least some amount of the surplus heat for

cooling applications.


CHPC systems can be easily integrated in factory sides supplying electricity, heat and cold

to existing manufacturing processes. They are combining the advantages of CHP systems

(Chapters 2.1.13, 2.1.14, 2.4.1 and 2.4.2) together with thermal cooling (Chapter 2.3.2).




TABLE 103: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR CHPC SYSTEMS


Fuel

Biomass

Hot water 90 – 110°C

Electricity power

Chilled water 6 – 18°C

Typical power range 5 kWel to several MWel

Typical corresponding cooling capacity 10 kW to several MW

SWOT Analysis of CHPC systems for industrial applications

TABLE 104: SWOT ANALYSIS FOR CHPC SYSTEMS – TECHNICAL ASPECTS


ST

RE

NG

HT

S Tri-generation (heat, cold, electricity)

Relatively easy combination with other technologies such as thermal collectors

High efficiency by year-round cooling needed

Coupled with an existing CHP unit

Storage for high efficiency required

Space for several components needed

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No space requirement for collectors

Still useable in low irradiation locations

Instead of various system only a single compact system (heat, cold, electricity)

Compete against a wide range of conventional technologies. E.g., those that using cheap electricity from the grid as input.

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TABLE 105: SWOT ANALYSIS FOR CHPC SYSTEMS – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S


Less installation and time costs

Rapid Amortization under long operation hours

Marketing aspects

Economical size range: CHPC using fuel fossils are available in sizes that match the electric demand of many end-users (institutional, commercial and industrial)

Environmental

CHPC reduces greenhouse gas emissions compare to other technologies


Relatively high capital cost

For small power ranges rather not profitable

CHPC with fuel (increase in fuel prices)

Marketing aspects

Lack of awareness in the industry W

EA

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SE

S

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Price reduction possible with higher production figures





The use of CHPC systems creates direct jobs in manufacturing, engineering, installation, ongoing operation and maintenance, and many other areas.


CHPC has strong dependence on fossil fuel prices (not particularly stable).

Natural gas and oil are a finite resource and as a result will not be a completely long term solution as more usage such as CHPC will drive up costs.


The use of renewable energies such as biomass.

The market share of fossil fuels will decrease.

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2.4.4. DISTRICT HEATING

Responsible Author:



District heating (DH) consists in the distribution of heat from one or more heat sources to

several consumers for space or water heating. It can be more energy efficient than

distributed generation of heat, in particular when exploiting waste heat from power plants or

industrial processes. It is significantly diffused in the Northern Europe countries (especially

Denmark, where DH heats about 60% of households), though notable installations can be

found in Southern Europe countries (see for example the DH of Turin in Italy).

The main components of a DH system are given by heat sources, distribution network, and

consumer sites. The distribution network typically runs a closed circuit, where heat transfer

with sources and consumers takes place through heat exchangers. The distribution pipes

are typically buried in the ground and water is the most common thermal vector fluid,

circulated by variable speed hydraulic pumps. Comprehensive overviews of district heating

can for example be found in [37, 38].

System layout

Different types of layouts are possible, the most common being the branch layout where

service lines for single households are derived from a main distribution line. In some cases,

a Daisy chain layout where some households are connected in series is also used. Typically,

a zoning approach is adopted, where buildings are grouped according to their relative

proximity. In the case of centralized heating, a single large heat source is present (e.g., a

waste incineration plant, see later). In the case of a decentralized system (less common),

multiple heat sources are integrated within the circuit.

FIGURE 58: LAYOUT OF A DH SYSTEM WITH HEAT STORAGE (SOURCE: RAMBOLL ENERGY)



System components:

Heat sources. CHP plants provide an excellent source, as the recovering of the waste

heat deriving from the electricity generation process significantly increases the overall

efficiency of the energy system. In the case where CHP plants are the main heat

source, a backup boiler is added to the system to cover peak demand and allow for

plant maintenance. Boilers can use natural gas or other fuels, often biomass. Another

common source for centralized DH systems is the heat generated by waste

incineration plants. For the manufacturing sector, decentralized DH systems are

probably of higher interest: possible sources are waste heat from industry, heat from

data centres, and solar heat. For the sake of completeness, nuclear plants and

geothermal plants (deep boreholes, e.g., 2,000 m depth as for the DH system of

Paris) should also be mentioned as possible heat sources.

Piping. Depending on the operating temperature of the system, two solutions are

possible: pre-insulated steel pipes (higher temperature) and flexible pre-insulated

plastic pipes (lower temperature). Several models with different insulation types and

sizes exist. The service life is always quite long (about 50 years is typically expected)

and the heat losses usually do not exceed 10%. At present, the tendency is to adopt

lower temperature solutions, where plastic pipes can be safely employed. In this

case, the inner service pipe is typically made of PE-Xa (cross-linked polyethylene),

with an insulating layer of foam (either PE or PU) and an external corrugated tube of

PE for protection. Plastic pipes typically offer lower costs and higher flexibility.

Thermal vector fluid. Three solutions are typically used: water, pressurized hot water,

steam.

Heat exchangers (HX). Plate heat exchangers are typically used within the pipe

network. They provide a good compromise between installation costs, pumping costs,

and heat transfer efficiency. Plate HX are modular and can hence be expanded after

installation, according to variations in heat demand. On the user side, plate heat

exchangers substitute usual boilers (consumer substations).

Hydraulic pumps. Variable speed pumps are the most common solution. They are

more expensive than fixed speed pumps but have several advantages: they allow a

finer control on the delivered heat (better match of demand), a lower electric

consumption and wear (operation only when needed), and lower heat losses (high

temperature in pipes only when needed). A back-up pump is often present (running

to cover peak demand/or in case of failure of the first pump).

Heat storage. Thermal storage is a good solution to cope with peak demand.

Moreover, in the case of coupling with the electricity grid (like for CHP), it offers

potential for peak shaving on the electric system. The storage system is often a large

water tank. Pit storage and geothermal storage are also used.

Heat meters. Through meters, users can pay according to consumption. Meters often

include remote reading, which allows the operating company for better planning and

monitoring (including alarm signals). As heat meters are more expensive, simple flow

meters are sometimes used (assuming standard operating temperatures). For

improved safety, pipes with embedded signal cables also exist.



Sizing and operating conditions:

Temperature. For plastic pipes the operating temperature is typically of about 80°C,

with a maximum temperature of 95°C. For steel pipes the operation temperature is

higher, of the order of 120 – 130°C. The temperature difference between flow and

return is usually at least 40°C. For a given thermal power demand, larger temperature

differences allow for lower flow rates, with consequent reductions in pump

consumption and/ or pipe size.

Flow rate. The nominal flow rate is typically determined by the heat demand and by

the flow-return temperature difference, used as design parameters.

Pipe diameter. The diameter can vary significantly, ranging from 25 mm for service

lines (for the final network of few houses / dwellings) to several hundreds of mm for

main distribution lines. It is convenient to keep the pipe size as small as possible, in

order to reduce pipe costs, installation costs, and heat losses. The pipe size is

determined by flow rate and pressure loss (the resulting velocity should be kept

smaller than about 3 m/s to avoid hydraulic issues).

Installation

Pipes are usually buried in the ground. The trench depth and width depend on the pipe size.

For plastic pipes, the depth is typically in the range 0.6 – 2.6 m, while the width extends

about 10 cm beyond the pipe size on each side; a spacing of the order of 10 cm between

flow and return is also recommended (unless pre-insulated double pipes are used). Similar

requirements exist for the distance from other utility pipes (gas, water, electricity). Plastic

pipes require some care in the laying process: in the proximity of the pipe, the trench is

covered with a layer of sand with specified grade.


Integration possibilities for DH networks strongly depend on the local situation. As the

installation of a DH network is quite costly, typically public institutions (municipalities) are

involved. In a few cases, however, DH associations are even started by private users.

For the manufacturing sector, DH can be an interesting option even more on the supply side

than on the demand side. There are examples of factories with a large availability of high-

temperature excess heat which found an agreement with public institutions in order to

provide heat to a DH network. This is of course much simpler in cases where the network

already exists, but it is also conceivable that, under proper conditions, it is the factory itself

that triggers the realization of the DH system.

Currently, a large interest in low-temperature DH network is present in Europe. Low-

temperature DH can reduce heat losses and can make easier the integration of multiple heat

sources, just as in the case of process heat from factories. In all the cases where a DH

network is already existent or at least taken in consideration by public institutions, the

possibility to use process heat as a source should be considered.

From the point of view of the physical connection with the pipe network, no particular issues

are present.




From the energetic point of view, the overall balance for DH systems is quite positive thanks

to the exploitation of waste heat from CHP or incineration plants. Heat losses due to the

network extension are typically contained within 10%.

In the present analysis, only the costs related to the piping network are considered. The

costs of integrating the DH network with heat sources and consumer substations are mainly

given by the adopted commercial components (heat exchangers, valves, heat meters).

Pipe overall installation costs for conventional (higher temperature) DH: 175 – 2,500

€/m depending on pipe size and location (e.g., city center vs. settlement areas) [39].

The pipe cost is typically of the order of 35% of the total [40].

The pipe cost for plastic pipes is roughly in the range 15 – 200 €/m for internal

diameters between 20 and 150 mm [41].

The costs for the end user are roughly in the range 0.025 – 0.1 €/kWh, depending on the

European country (for example, the cost is about 0.08 €/kWh in North Italy).

Modelling input / output information

The following table contains a short list of variables and parameters useful for the system

modelling.

TABLE 106: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR DISTRICT HEATING


Heat sources (operating temperature and temperature drop)

Distribution system (pipe length)

Consumer substations (heat power demand)

Supply temperature

Flow rate

Pipe size

Pressure difference

Storage volume



SWOT Analysis of district heating systems for industrial application

The following SWOT analysis is mainly conducted from the point of view of a manufacturing

company interested in exploiting / recovering waste process heat, becoming a supplier of a

DH network.

TABLE 107: SWOT ANALYSIS OF DIRECT HEATING SYSTEMS – TECHNICAL ASPECTS


ST

RE

NG

HT

S

Increases the overall energy use efficiency when waste heat is used as a source.

The technology cannot be installed in special areas.

Less convenient in areas with low heat demand (low density buildings and/or highly energy efficient houses and/or warm climate).

Higher noise than independent boilers.


WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S

Integration with different energy sources.

Low temperature districting heating with heat pumps.

Integration with district cooling.


TH

RE

AT

S

TABLE 108: SWOT ANALYSIS OF DIRECT HEATING SYSTEMS – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S



A DH system can convert waste heat into economic revenues.

Often convenient with respect to independent boilers on the user side.

Marketing aspects

No visual impact.

It can be related to public initiatives or consumer associations.


Installation costs are high.

Marketing aspects

Monopolistic aspects and lower independency for end user.

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S


Increase in fuel prices.

Convenient on the long run.


Presence of incentives when public investment is involved in DH.








Increasing performances and/or price lowering of other solutions.

TH

RE

AT

S



2.4.5. DISTRICT COOLING

Responsible Author:



District cooling (DC) consists in the distribution of cold from one or more cold sources (heat

absorbers) to several consumers for space cooling. It shares many aspects with DH, often

exploiting the same network. Due to the diffusion of DH in Northern Europe, district cooling

examples can be found in those countries in spite of the relatively low cooling demand. A

potentially large market is expected in Southern Europe.

The general layout of a DC system is the same as that of a DH system and therefore is not

repeated here. Instead, the main differences with respect to DH are pointed out [37, 38].

System layout:

For the general layout, please refer to the DH description (Chapter 2.4.4 and Figure 58).

System components:

Cold sources. The generation of cold can occur with three methods: compression

heat pumps, absorption heat pumps, and natural resources (lakes). Compression

and absorption heat pumps are described in the corresponding sections. Natural

resources requires special conditions to be exploited (e.g., proximity of lakes or sea)

and are not further described here. As far as the manufacturing sector is considered,

it is important to point out that absorption heat pumps can exploit waste heat for the

production of cold.

Piping. See the DH description. For independent DC systems, buried pipes are often

non-insulated, as the small temperature difference with the ground gives rise to

gains / losses whose cost is negligible with respect to the additional cost required by

insulation. The same piping network of a DH system can also be exploited, the most

natural integration occurring with low-temperature district heating and pre-insulated

plastic pipes (see DH description for more details).

Thermal vector fluid. Three solutions are typically used: water, water-glycol mixtures

(about 10% propylene glycol), ice slurry (water being by large the most common).

Heat exchangers. See DH description. Special solutions are required for ice slurry.

Hydraulic pumps. See DH description. Special solutions are required for ice slurry.

Note that for DC variable speed is particularly important also for pumps on the

consumer side, in order to ensure a large enough flow-return temperature difference.

Heat storage. Water or ice storages are used. Ice storages typically allow to save

75% of the volume used by a water storage, thanks to the higher energy density given

by latent heat. On the other hand, the management of ice storages is typically more

complicated.

Heat meters. See DH description.



Sizing and operating conditions:

Temperature. The flow temperature is typically 1 – 4°C, for ice-water or water

systems respectively. The return temperature is typically of 12°C, yielding a much

lower temperature difference than for DH. This determines higher challenges in terms

of flow rate, pipe size, and system control.

Flow rate. The nominal flow rate is typically determined by the cold demand and by

the flow-return temperature difference, used as design parameters.

Pipe diameter. See DH description. When sizing a pipe network for both heating and

cooling, it is necessary to consider the different thermal power demands and

temperature drops, verifying the limiting conditions.

Installation:

For the installation, please refer to the DH description (Chapter 2.4.4).


The general comments reported in the DH description are valid also for DH networks. It

should be emphasized the possibility of using waste heat to drive absorption chillers.


The general comments reported in the DH description are valid also for DH networks. In the

case of non-insulated pipes, significantly lower costs are obtained. The following table

contains a short list of variables and parameters useful for the system modelling.

TABLE 109: MAIN INPUTS, OUTPUTS AND GENERAL PARAMETERS FOR DISTRICT COOLING


Cold sources (operating temperature and temperature drop)

Distribution system (pipe length)

Consumer substations (cold power demand)

Supply temperature

Flow rate

Pipe size

Pressure difference

Storage properties



SWOT Analysis of district cooling systems for industrial applications

TABLE 110: SWOT ANALYSIS OF DIRECT COOLING SYSTEMS – TECHNICAL ASPECTS


ST

RE

NG

HT

S

Increases the overall energy use efficiency when waste heat is used with absorption pumps.

The pipe network cannot be installed in special areas.

Less convenient in areas with low cooling demand (low density buildings and/or highly energy efficient houses and/or cold climate conditions).

Higher noise than independent chillers.


A DC network might be absent.

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S

Integration with low temperature districting heating.


TH

RE

AT

S

TABLE 111: SWOT ANALYSIS OF DIRECT COOLING SYSTEMS – COSTS, MARKETING AND ECOLOGY


ST

RE

NG

HT

S



A DC system can convert waste heat into economic revenues.

Often convenient with respect to independent chillers on the user side.

Marketing aspects

No visual impact.

It can be related to public initiatives or consumer associations.


Installation costs of the network are high.

Marketing aspects

Monopolistic aspects and lower independency for end user.

WE

AK

NE

SS

ES

OP

PO

RT

UN

ITIE

S


The system is expected to be convenient on the long run.


Presence of incentives when public investment is involved in DC.




Increasing performances of building envelopes (lowering cooling demand and making it difficult to recover the high installation costs for the supplier).




Increasing performances and/or price lowering of other solutions.

TH

RE

AT

S



3. ASSESSMENT AND RANKING





3.1. METHODOLOGY DESCRIPTION

3.1.1. SWOT ANALYSIS

A SWOT analysis including economic and environmental factors has been used for the

assessment of screened technologies inside each cluster to prioritize the best technologies

to be then modelled. A ranking with 1 – 2 options for each cluster has been set up to create

the dataset or library as input for the development of the virtual decision support tool.

SWOT analysis related to screened / clustered technologies:Figure 59

Strengths: characteristics of the technology that

give it an advantage over others

Weaknesses: characteristics that place the

technology at a disadvantage relative to others

Opportunities: elements that the technology could

exploit to its advantage

Threats: elements in the environment that could

cause trouble for the technology

3.1.2. TECHNOLOGY RANKING

Introduction

As already explained in the introduction of this document, one of the goals of the REEMAIN

project is to help the industry field to adopt energy technologies with a higher efficiency and

sustainability. To this purpose, several potentially promising technologies were selected and

described in the previous sections. The next step, requires to compare and rank these

technologies, in order to identify the most suitable ones to be readily applied in the three

industrial sectors considered in REEMAIN.

Such a complex evaluation clearly involves different aspects. Several factors have to be

analysed, and the performance of each technology from different points of view has to be

considered. The SWOT (Strengths, Weaknesses, Opportunities, Threats) analysis

presented in each technology description provides a first step in this direction. However, its

qualitative results are not easily converted into an explicit ranking, where one technology is

clearly preferred to the other. In order to obtain a more quantitative comparison, a more

systematic approach is adopted in this section, following methods often used in the field of



multi-criteria decision analysis (MCDA). Framing the ranking problem in this context, a

methodology as flexible and transparent as possible was developed.

Weighted decision matrices

General description

There is a series of possible methods, which can be borrowed from MCDA [42]. The

approach adopted here is a weighted sum model based on a weighted decision matrix. In

practice, first a list of criteria influencing the choice (factors contributing to the performance)

of the considered alternatives (technologies) is compiled. Then, the importance of each of

these criteria is established through a weight (a number on a certain scale). Finally, for each

criterion, a score (another number on a different scale) is assigned to the considered

alternative. The global score of the alternative is calculated as the weighted average of the

scores corresponding to each criterion. Hence, with respect to the SWOT analysis, a more

structured list of key “questions” (criteria, factors) is decided and organized in a form, which

can be answered in a more “measurable” way.

Hereafter, the main ingredients of the weighted sum approach are summarized, along with

some general comments about their use and interpretation:

Criteria / factors: In the present context, factors are aspects, which are significant

to evaluate the potential of a certain technology. These include technical factors, cost

factors, and others. Factors can be arranged into categories, as done in the PEST

(Political, Economic, Social, Technological) analysis and its variants. The choice of

factors used here is specified below.

Weights: These are numbers representing the importance of each factor. Indeed,

while several aspects contribute to the evaluation of an alternative, their relevance is

typically different. Weights must be positive and include a normalization process (see

below).

Scores: These numbers represent the “performance” of an alternative for a given

factor. The corresponding scale can be chosen arbitrarily (see below for the chosen

one), but it is crucial that it be the same for all the factors.

The IFE/EFE matrices example

An example of weighted sum approach is provided by the IFE/EFE matrix technique (Internal

Factor Evaluation and External Factor Evaluation matrix). This method is interesting

because it keeps the distinction between internal/external and helpful / harmful factors as in

the SWOT analysis. Indeed, in the IFE/EFE matrices internal factors correspond to strengths

and weaknesses, while external factors to opportunities and threats. A weight 𝑤𝑖 ∈ (0,1) is

assigned to the 𝑖-th factor, so that the sum of all the weights is ∑ 𝑤𝑖𝑖 = 1 (normalization

conditions). Moreover, a score 𝑠𝑖 is assigned to the 𝑖-th factor as follows:

1 to major weaknesses / threats

2 to minor weaknesses / threats

3 to minor strengths / opportunities

4 to major strengths / opportunities



The overall score of a certain alternative is calculated as the weighted sum of all the factor

scores, that is

𝑆 = ∑ 𝑤𝑖𝑠𝑖

𝑖

.

In the case of uniformly distributed random scores, the average score is 2.5.

Implemented methodology

In the present case, a slight variation of the IFE/EFE matrices approach was implemented.

In the following, the adopted choices for the scales of weights and scores are explained in

detail.

Weights

As already explained, the weight is used to assess the level of importance of a given factor.

It was found to be unpractical to directly assign the weights in the range (0,1) under the

normalization condition ∑ 𝑤𝑖𝑖 = 1. Instead, here the importance level was rated with a 3-

value scale as low / medium / high. This is then converted into an integer number (𝑤𝑖 ∈

{1,2,3}) and a normalization factor is later applied (see below). This was decided to be a

reasonable compromise between flexibility and practicality.

Scores

The strengths / weaknesses distinction, while useful when assessing a single technology,

makes it more difficult to prepare a list of factors valid in general. Indeed, some factors would

more conveniently appear as strengths for some technologies and as weaknesses for

others. Hence, it is more natural to include them as “neutral” factors and rely on the score

to rate them as positive or negative. Similarly to the structure of the IFE/EFE scores, here it

was used a 5-value scale as very-low / low / medium / high / very-high rating, converted into

integer numbers so that 𝑠𝑖 ∈ {-2,-1,0,1,2}. This reflects the minor / major distinction used in

the IFE/EFE score, while adding a neutral value (0) for cases where the factor is neither a

strength, nor a weakness. The average score (with respect to uniformly distributed random

scores) is now 0 instead of 2.5.

Presence flags

Considering the exploratory nature of the present evaluation, a presence flag 𝑞𝑖 was

assigned to the 𝑖-th factor, so that 𝑞𝑖 = 1 if the factor has been evaluated and 𝑞𝑖 = 0

elsewhere. This was introduced to take into account the possibility that for some

technologies the evaluators could be unable to provide a score for all the included factors.

The overall score for a given technology is then evaluated as

𝑆 =∑ 𝑤𝑖𝑞𝑖𝑠𝑖𝑖

∑ 𝑤𝑖𝑞𝑖𝑖 ,

where the denominator corresponds to the normalization factor mentioned above.



Factors

In the following, a table reporting the chosen factors and their grouping is included.

TABLE 112: FACTOR AND GROUPING FOR RANKING MATRIX (SOURCE: EURAC, JER)

Factor group

Factor Help questions Factor type

Weight Relative group weights

Technical Applicability and

Flexibility Can the technology be applied

to several situations?

Is the technology versatile, e.g., does it apply to a wide range of temperatures?

Internal 1 9/20

(45%)

Space

compactness Can the technology be installed

within a compact space?

Is it typically possible to find an available space to install it?

Internal 2

Integration Is it easy to integrate the technology with existing buildings, plants, and processes?

Can it be typically installed without large modifications or refurbishments?

Can it be considered a "plug & play" technology?

Internal 3

Duration,

reliability, and

maintenance

How long is the life time?

Is it reliable (consider also intermittency issues)?

Does it require maintenance seldom?

Internal 3

Economic Installation and

investment costs Are investment (including

financial aspects) and installation costs cheap / viable?

Internal 1 2/20

(10%)

Operation and

maintenance

costs

Are operation costs cheap / viable?

Are maintenance costs low?

Internal 1

Marketing Country

independency Is the technical and economic

convenience the same for different countries across Europe?

External 1 3/20

(15%)

Acceptance and

diffusion Is the technology well

assessed?

Is it typically trusted?

Is it diffused on the market?

External 2

Environ-mental

Renewability Is the technology highly based on renewable sources?

Internal 3 6/20

(30%)

Pollution free Is this a “clean” technology?

Does it have a low emission of pollutants?

Internal 3



Table 112 shows the four categories chosen for the evaluation factors, some help questions

used to explain the meaning of the different factors, the factor type (internal or external in

the sense of the SWOT analysis), and the corresponding weights. Summarizing by category,

one has:

Technical (4 factors, category weight 45%)

Economic (2 factors, category weight 10%)

Marketing (2 factors, category weight 15%)

Environmental (2 factors, category weight 30%)

Concerning the weights, it should be noted that the present choice is clearly oriented by the

REEMAIN objectives. In the industrial sector, the importance attributed to the economic

factors is of course typically higher. In this context, however, where developing technologies

are considered and a strong focus on sustainability is adopted, it was important to provide

precedence to other factors. This is in line with the “roadmap” concept explained in the

document introduction: the present ranking aims at highlighting the most promising

technologies in an energy sustainability perspective, where the reduction of fossil fuel

consumptions is a priority.

It is anyway interesting to consider the influence of weights on the global score. As

previously explained, the global score 𝑆 is a weighted average (presence flags are not

relevant here)

𝑆 =∑ 𝑤𝑖𝑠𝑖𝑖

∑ 𝑤𝑖𝑖

The dependence of the global score on a single weight can be calculated in terms of

derivatives. The “marginal” score (score variation due to a variation of “1” in a weight) is

𝜕𝑆

𝜕𝑤𝑖=

𝑠𝑖 − 𝑆

∑ 𝑤𝑗𝑗

In our case the total weight is 𝑊 = ∑ 𝑤𝑗𝑗 = 20, while the maximum possible difference

between the scores at the numerator is ±(2-(-2)) = ±4. Hence

|𝜕𝑆

𝜕𝑤𝑖| ≤

4

20 ,

that is, the maximum possible variation in the global score due to a unit change in a weight

is 0.2.

Simultaneous variations of multiple weights can of course yield higher variations in the global

score, but the previous analysis can provide an order of magnitude for the global score

sensitivity with respect to weights.

Technology classification

As explained at the beginning of this document, different technology clusters were

considered. Indeed, different applications can be identified within the energy context. When

providing a ranking, it is therefore necessary to distinguish among these clusters, as it would



be of scarce interest, for example, to compare the score of a technology for energy

generation with that of a technology for energy storage. The performance of a device has to

be evaluated with respect to the corresponding application.

On the other side, a technology classification with a reasonable level of detail has to be

identified, in order to ensure the formation of comparison groups of significant size. Within

this task, a rather general analysis was carried out. Therefore, only the following distinction

was considered for the possible application of the various technologies:

Heat generation

Cold generation

Electricity generation

Poly-generation

Storage

These are rather broad clusters, which sometimes include devices actually applied in

different contexts. However, also in relation with the number of technologies in the list, this

was found to be an acceptable level of detail in order to separate systems belonging to very

different applications, while at the same time avoiding an excessive fragmentation of

technologies.

In the following, for the sake of completeness, a few possibilities for a more detailed

classification are outlined, also in view of possible extensions of this work.

Classification extensions

The proposed more detailed classification is based on energy-oriented and application-

oriented principles. Moreover, it considers the kind of analysis which is expected for the

decision making support tool to be developed in task T3.4. In that context, the evaluation

will start from specific needs, where the applications arising from the processes operating

at the factory sites will drive the technology choices.

In a rather schematic way, the following attributes to be used in the classification are

proposed.

Energy-oriented:

o Energy type (thermal, electrical, mechanical).

Energy quality (thermal: cold / low / mid / high temperature range)

Application-oriented:

o Energy treatment / manipulation

Energy generation

Energy storage

Energy transformation (transfer, transmission, distribution, exchange,

dissipation, conversion)

Energy-oriented and application-oriented attributes can be combined together to form a

“faceted” classification. For example, one could build a technology (sub-) cluster related to

the generation (application-oriented attribute) of thermal energy (energy-oriented attribute)

in the high (> 400°C) temperature range (energy-oriented sub-attribute).



Concerning the application-oriented attributes, it should be noted that while energy

generation and energy storage can be related to a single energy type and quality, energy

transformation typically involves an “input” and an “output” energy type and/or quality. This

would create a large number of sub-classes defined by the corresponding combinations. For

example, the sub-class given by all the technologies for the conversion of thermal energy in

the mid temperature (100 – 400 °C) range into electrical energy could be considered.

In principle, a technology classification can reach extremely high levels of detail (as

exemplified by the classification used in the patent context). The identification of meaningful

and useful classes would require some further analysis with respect to the short discussion

presented here. In the context of this project, however, more than a general theoretical

classification it was important to identify practical groups of technologies to be preliminary

evaluated and considered for the development of factory analysis software tools.

Possible extensions

In the field of MCDA, several different methods of evaluation have been developed. While

the main ingredients are typically always the same (factors, weights, scores), the way they

are evaluated and used can vary. According to the short literature review done for this task,

after the weighted sum approach, the two most frequently applied methodologies are the

weighted product approach and the analytic hierarchy process (AHP). In the following, a

short description of these two methods is presented, along with their advantages and

disadvantages with respect to the weighted sum.

Weighted product

In this approach, the overall score 𝑆 is obtained as the product of the scores 𝑠𝑖 assigned to

single factors, each of them weighted with a specific exponent 𝑤𝑖. The mathematical

representation is then

𝑆 = ∏ 𝑠𝑖𝑤𝑖

𝑖

.

To compare with the weighted sum approach used here, it is useful to take the logarithm of

the previous expression, which yields ln 𝑆 = ∑ 𝑤𝑖 ln 𝑠𝑖𝑖 . This shows that the weighted product

can be converted into a weighted sum, where, however, the scores are expressed in a

logarithmic scale. For obvious reasons, in the weighted product the scores are assumed to

be positive. The main difference with respect to the weighted sum is that, in the weighted

product, a single factor can affect the result in a critical way even in the presence of equal

weights. Indeed, if even only one single factor receives a zero score, also the global score

is zero. This can be useful in situations when several different conditions must be met,

similarly to the “AND” operator in Boolean expressions.

Analytic hierarchy process (AHP)

In the AHP approach, a simple weighted sum is used. However, the way in which the weights

and the scores are assigned follows a precise procedure, which can improve the reliability

of these values. Weights are established through pairwise comparisons among the different

factors (criteria). In practice, the importance of each factor with respect to another one is

evaluated and fixed in terms of a relative scale. Loosely speaking, it is decided “how many



times” one factor is more important than another. A consistent evaluation requires that, for

example, if factor B is two times more important than factor A, and factor C is three times

more important than factor B, than factor C is six times more important than factor A.

However, the mathematical procedure used to extract the final weight distribution allows to

cope with slight inconsistencies, so that the evaluation procedure for a given pair can be

done without having to keep accurately track of other evaluations. The same kind of analysis

allows to assign scores starting from the pairwise comparison of all the possible alternatives

for each given factor. In our case, the alternatives would be given by the different

technologies. Combining in a weighted sum the weights for each 𝑖-th factor with the scores

𝑠𝑖,𝑗 for the 𝑗-th alternative with respect to the 𝑖-th factor, one gets the total score for the 𝑗-th

alternative as

𝑆𝑗 = ∑ 𝑤𝑖𝑠𝑖,𝑗

𝑖

,

where here the normalization is implicit in the weights (i.e., in AHP the constraint ∑ 𝑤𝑖𝑖 = 1

is used).

It is worth noticing that in AHP the exhaustive pairwise comparison and the relative scale

used for the corresponding evaluation provide a sort of implicit benchmarking (i.e., the need

for an external benchmark is avoided). The result is a relative ranking among the considered

alternatives, without any absolute score. This is an advantage with respect to the weighted

sum used in our case.

On the other side, it is easy to see that the work involved in the AHP method quickly

increases with the number of factors / criteria and alternatives. In particular, the number of

pairwise comparisons is given by the binomial coefficient, i.e., for 𝑛 items one has

𝑛(𝑛 − 1) 2⁄ pairs to compare. Our case involves a number of factors and alternatives, which

would be rather challenging from this point of view, making this a disadvantage for the

application of AHP.

A final comment concerns the use of AHP in a “collaborative decision making” context. The

AHP analysis is typically more consistent (in the sense that the pairwise comparisons are

typically more harmonized) if a single evaluator carries out the full analysis. However, this

requires a significant effort from the evaluator and does not ensure better results (unless the

considered evaluator is provided with an extremely broad expertise on all the involved

matter). In real cases, more people participate in the evaluation. This is the approach

adopted also in this task: different experts for different technologies where involved, without

requiring that each evaluator had an advanced knowledge of all the technologies included

in the screening. To analyse and reduce biases among the different evaluators, an external

survey was carried out and its results were communicated to the internal evaluators before

the final ranking was completed. Since each internal expert was involved in at least a couple

of technologies and was aware of the scores assigned by external experts to a group of

reference technologies, it is expected that some compensation with respect to the possible

discrepancies caused by the interaction of different non-all-knowing individuals is provided.

The application of the AHP method with this collaborative approach (possibly reducing the

number of pairwise comparisons applying some recursive evaluation) could provide an

interesting development of this work.



3.2. RESULTS OF TECHNOLOGY RANKING

3.2.1. TECHNOLOGY RANKING FOR CLASSIFICATION CLUSTERS

For all screened and described innovative RES, storage, waste recovery and energy-

efficient hybrid systems the developed ranking methodology (Chapter 3.1) based on factors

and grouping for a ranking matrix (Table 112) was applied by each technology leader from

Activity 3 to evaluate their described technology. The overall results of this first technology

ranking are presented in Table 113.

TABLE 113: TECHNOLOGY RANKING FOR CLASSIFCATION CLUSTERS (SOURCE: JER)



FIGURE 59: TOTAL SCORES OF TECHNOLOGY RANKING FOR CLASSIFICATION CLUSTERS (SOURCE: JER)

FIGURE 60: SINGLE SCORES OF TECHNOLOGY RANKING (TECHNICAL, ECONOMIC, MAREKTING AND ENVIRONMENTAL)

(SOURCE: JER)



The total scores of the 32 ranked technologies is shown in Figure 60, where only thermal oil

storage (cluster no. S.1.1.3) has a negative score of -1.00. There are seven other

technologies also with a very low total score below 0.20. All the other technologies have

total scores more ore less above 0.50. The highest achieved total score is 1.75 for the PV

technology (cluster no. R.2.1).

Figure 61 indicates the difference in scoring within the four groupings (technical, economic,

marketing and environmental). In general, the technical scores of all technologies shows

that 29 of 32 technologies have positive scores. This means that from a technical point of

view the screened and described technologies are all technical wise feasible for the use and

integration into manufacturing processes. On the other hand, the economic scores show a

different picture, where 10 of 32 technologies (one third) have a negative score. This means

these technologies are not economical because of high investment costs and therefore need

incentives to be installed. The marketing of the various technologies is also valued

differently. 13 of 32 technologies have positive scores (good marketing to sell the

technologies), but the rest has either a neutral or a negative score (no good marketing or

the technologies are not well known in the industry). The environmental scores show a very

a nice picture, where all RES technologies have a very high score (mainly above 1.00) as

well as all waste recovery technologies have positive scores. On the other hand, three of

the 8 storage technologies have negative scores (thermal storage either with thermo oil,

concrete / rooks or cast iron / steel). Finally, four of the five energy efficient hybrid systems

have also negative environmental scores, because if fossil fuels are used as energy source.

3.2.2. TECHNOLOGY RANKING FOR GENERATION CLUSTERS

A different presentation and analysis shows the following Figure 61 where the ranking is

clustered after the different generation clusters (cold-, electricity-, heat-, poly-generation and

storage). This division makes the selection for the most promising innovative technologies

mainly related to the three industry sectors of the REEMAIN project easier. The comparison

of the total scores is also presented in Table 114.

FIGURE 61: TOTAL SCORES OF TECHNOLOGY RANKING FOR GENERATION CLUSTERS (SOURCE: JER)



TABLE 114: TECHNOLOGY RANKING FOR GENERATION CLUSTERS

The following Figure 62 – Figure 66 are presenting for each generation cluster (cold-,

electricity-, heat-, poly-generation and storage) the comparison of the total scores of the

ranked technologies in each generation cluster.

For the cold generation cluster the solar cooling technology (cluster no. R.1.5) with a total

score of 0.80 seems to be the best option. In the electricity generation cluster the PV

technology (cluster no. R.2.1) with a total score of 1.75 is the best option followed by wind

turbines (total score of 1.64, cluster no. R.2.4). For heat generation two technologies are

recommended for heat supply for manufacturing processes, especially solar thermal

collectors with a total score of 1.53 (cluster no. R.1.2) and solar concentrators with a total

score of 0.70 (cluster no. R.1.3). The ORC system has the best ranking within the poly-

generation cluster (cluster no. W.1.1.) where the total score is 1.00. Finally, in the storage

cluster the hot water thermal storage (total score of 1.40, cluster no. S.1.1.1) and the

battery / electricity storage (total score of 1.15, cluster no. S.3.1) are ranked as the best

options for both different applications.



FIGURE 62: TOTAL SCORES OF TECHNOLOGY RANKING FOR COLD GENERATION CLUSTERS (SOURCE: JER)

FIGURE 63: TOTAL SCORES OF TECHNOLOGY RANKING FOR ELECTRICITY GENERATION CLUSTERS (SOURCE: JER)

FIGURE 64: TOTAL SCORES OF TECHNOLOGY RANKING FOR HEAT GENERATION CLUSTERS (SOURCE: JER)



FIGURE 65: TOTAL SCORES OF TECHNOLOGY RANKING FOR POLY-GENERATION CLUSTERS (SOURCE: JER)

FIGURE 66: TOTAL SCORES OF TECHNOLOGY RANKING FOR STORAGE CLUSTERS (SOURCE: JER)



3.2.3. INTERNAL AND EXTERNAL SURVEYS

Based on the results of the internal technology ranking (Chapter 3.2.1 and 3.2.2) a further

internal and external survey was prepared to get an additional benchmark for six pre-

selected innovative technologies (solar concentrators, PV, solar cooling, CHPC, ORC,

battery storage) Therefore, an e-mail survey poll was set up based on the previous

developed ranking matrix (Table 112) using Excel where the reviewers had to fill in the

technology ranking survey for the six pre-selected technologies. The aim of this survey was

to evaluate our own scores given for the different main promising technologies and to

compare these scores with the scores given by the internal and external reviewers / experts

(as a benchmark).

The references for the pre-selected technologies are: parabolic trough collector, poly- and

mono-crystalline PV, solar cooling system with absorption chiller, engine-based CHPC

system, ORC applied to medium temperature sources and lithium-ion battery storage.

Based on 14 external reviewer returns (8 to 19 returns for the different technologies have

been expected -> average 13.3 reviews) a final assessment for the benchmark was carried

out. Depending on the technology finally 175% to 75% feedbacks were received, because

many external reviewers have filled in the survey for all 6 selected technologies! A similar

picture shows the additional internal review with 20 completed surveys from REEMAIN

experts, which were almost not involved in the preparation of the technology roadmap.

The results of the internal and the external survey (both based on pre-selected reference

technologies, validation and benchmarking purpose) are presented in the following Figure

67 – Figure 72. The figures show the total score comparison as well as the sub-score

comparison of each selected technology (REEMAIN expert vs. internal and external

benchmark).

The analysis for the Solar Concentrator technology survey comparison (Figure 67)

indicates that the REEMAIN expert has ranked the technology with 0.70 (total score) against

0.46 ±0.26 standard deviation (internal benchmark) and 0.61 ±0.39 standard deviation

(external benchmark). In general, the internal and external reviewers have similar scores as

the REEMAIN expert. At the sub-scores there are two deviations in the technical and

economic view between the internal reviewers and the REEMAIN / external experts.

Marketing seems to be an issue for this technology, which should be overcome in the future

to install more systems into manufacturing processes.

The PV technology has received again the highest total score from all reviewers among

the six pre-selected technologies (Figure 68). The REEMAIN expert has ranked the

technology with 1.75 (total score) against 1.12 ±0.37 standard deviation (internal

benchmark) and 1.20 ±0.31 standard deviation (external benchmark). All sub-scores of the

internal and external reviewers are similar and positive!

The third selected technology, Solar Cooling, is ranked by the internal and external

reviewer with a total score of 0.36 ±0.45 standard deviation (internal benchmark) and 0.53

±0.59 standard deviation (external benchmark), respectively, against 0.80 of the REEMAIN

expert. Only the economic rating is different between the internal reviewers and the



REEMAIN / external experts (Figure 69). All other sub-scores are similar, but again

marketing seems to be also an issue for this technology.

The CHPC technology assessment shows that REEMAIN expert has ranked the

technology with 0.50 (total score) against 0.12 ±0.47 standard deviation (internal

benchmark) and 0.22 ±0.59 standard deviation (external benchmark). Similar to the solar

cooling technology there is a mismatch of the economic and environmental ranking between

the internal reviewers and the REEMAIN / external experts (Figure 70). Furthermore, the

REEMAIN and external experts thinking that the technology itself is not very environmental

friendly.

The analysis of the ORC technology (Figure 71) indicates that the REEMAIN expert has

ranked the technology with 1.00 (total score) against 0.05 ±0.47 standard deviation (internal

benchmark) and 0.22 ±0.69 standard deviation (external benchmark). The REEMAIN expert

sees this technology much more positive then the internal and external reviewers. The

economic and marketing sub-scores are both negative from the perspective of the internal

and external reviewers.

The final reviewed technology is the battery storage technology. Here the REEMAIN

expert has ranked the technology with 1.15 (total score) against 0.23 ±0.61 standard

deviation (internal benchmark) and 0.21 ±0.55 standard deviation (external benchmark).

There are again different views for the economic, marketing and environmental sub-scores

between the REEMAIN expert and the internal / external reviewers. The external reviewers

view especially the environmental aspect negatively (Figure 72).

Comparison of total and sub scores:

FIGURE 67: TOTAL / SUB-SCORE COMPARISION OF SOLAR CONCENTRATOR TECHNOLOGY RANKING (SOURCE: JER)



FIGURE 68: TOTAL / SUB-SCORE COMPARISION OF PV TECHNOLOGY RANKING (SOURCE: JER)

FIGURE 69: TOTAL / SUB-SCORE COMPARISION OF SOLAR COOLING TECHNOLOGY RANKING (SOURCE: JER)

FIGURE 70: TOTAL / SUB-SCORE COMPARISION OF CHPC TECHNOLOGY RANKING (SOURCE: JER)



FIGURE 71: TOTAL / SUB-SCORE COMPARISION OF ORC TECHNOLOGY RANKING (SOURCE: JER)

FIGURE 72: TOTAL / SUB-SCORE COMPARISION OF BATTERY STORAGE TECHNOLOGY RANKING (SOURCE: JER)

The sensitivity analysis (Chapter 3.3) about the scores (including standard deviation, etc.)

shows narrower variance for more established technologies (PV), as reasonable. It is

possible that underlying effects (country dependency of reviewers, sectors dependency of

reviewers, etc.) influence the ranking. That could be interesting to investigate in the future,

but requires a much broader sample to achieve statistical significance. In general, there is

a rather narrow distribution of scores (maybe partly due to the similar level of the

technologies in the list and partly to the limited extension of the available scale). The

sensitivity analysis about weights was considered in Chapter 3.1 in terms of marginality.



3.3. SENSITIVITY ANALYSIS

Different alternatives were investigated in order to validate the proposed ranking tool. Based

on different perspectives, two alternatives were analysed in more detail. Reasons and

weights are declared in the following.

Original: Factors for the original ranking are oriented on the REEMAIN manufacturing

objectives as mentioned in Chapter 3.1.2.

Alternative 1: The aim of alternative 1 is a homogenisation across all factor groups. Each

factor group is weighted with 25%, thus it creates an equal weighting. To accomplish this,

values were adjusted to get the same sum of values in each category.

Alternative 2: For the second alternative, an attempt was made to generate an

entrepreneurial point of view. With 54.1%, the economic factor has the highest weighting.

Table 115 shows the weighting of these different proposals. The table presents value and

category weighting as well as the difference between the technical, economic, marketing

and environmental aspects.

TABLE 115: WEIGHT FACTORS FOR THE SENSITIVITY ANALYSIS

The weighting system described in the Technology Roadmap imposes weights to be integer

numbers in the range from 1 to 3. This was chosen because of the following reasons:

Simplicity: In this way it is straightforward to assign weights in terms of importance

(low/medium/high). Simplicity was especially important for the case where weights

could be established in a collaborative way among several partners.

Balancing: It seems not very reasonable to keep factors with very different importance

together. If a factor is 10 times less important than another, the most reasonable

choice is to exclude it from the list. The list of factors itself was chosen having in mind

simplicity: the number of factors had to be limited and the idea was to keep only most

representative factors. Anyway, the range of 1 – 3 allows to include factors 3 times

more important than others. This was considered a difference large enough.



The variation of the total score due to the variation of a single weight within the used scoring

system (i.e., variation of a weight by 1) can be calculated as the following derivative:

𝜕𝑆

𝜕𝑤𝑖=

𝜕

𝜕𝑤𝑖

∑ 𝑤𝑗𝑠𝑗𝑗

∑ 𝑤𝑗𝑗=

𝑠𝑖

∑ 𝑤𝑗𝑗−

∑ 𝑤𝑗𝑠𝑗𝑗

(∑ 𝑤𝑗𝑗 )2 =

𝑠𝑖 − 𝑆

∑ 𝑤𝑗𝑗=

𝑠𝑖 − 𝑆

20

where the sum of the weights was calculated with the used values.

The following Figure 73 – Figure 77 show the final results of the sensitivity analysis for the

five clusters. Within each figure a comparison is presented for the different alternatives

(orginal total score, alternative 1 and 2). The range of scores is chosen to be equal as the

investigations above (-2 until +2).

For the sensitivity analysis based on alternative 1 with equal weighting, only one technology

resulted in an opposite, negative total score against the original one, which is the thermal

heat storage with steel from the storage cluster (Figure 77). This shows, that an equal

distribution of the weighting doesn’t change the general picture of the calculated total scores

of the other technologies.

For alternative 2, an analysis with strong focus on economic conditions and with a total of

7 technologies from the five clusters get total scores below zero. These are thermal cooling

(Figure 73), CSP (Figure 74), biomass and heat pump (Figure 75), biogas driven CHP

(Figure 76) and thermal storage with steel as well as the PCM technology (Figure 77). This

results, that those technologies are not as attractive as the other analysed technologies, for

integration in efficient manufacturing from an economic point of view.

FIGURE 73: COMPARISON OF DIFFERENT ALTERNATIVES, COLD CLUSTER (SOURCE: JER)



FIGURE 74: COMPARISON OF DIFFERENT ALTERNATIVES, ELECTRICITY CLUSTER (SOURCE: JER)

FIGURE 75: COMPARISON OF DIFFERENT ALTERNATIVES, HEAT CLUSTER (SOURCE: JER)



FIGURE 76: COMPARISON OF DIFFERENT ALTERNATIVES, POLY CLUSTER (SOURCE: JER)

FIGURE 77: COMPARISON OF DIFFERENT ALTERNATIVES, STORAGE CLUSTER (SOURCE: JER)



Overall uncertainty derives from both weight sensitivity and score sensitivity. Therefore,

the role of both sensitivities in the overall picture was also investigated in further detail.

- Weight sensitivity: roughly estimated as the average “variability” of the results

obtained with the three alternatives using all available scores

→ 𝜎𝑤 ∼ 0.2

- Score sensitivity: roughly estimated as the standard deviation of the results obtained

from the surveys (int/ext) using the original weights

→ 𝜎𝑠 ∼ 0.5

- Overall uncertainty: mean square root of the two contributions (as typical for statistical

analysis)

→ 𝜎𝑜𝑣 = √𝜎𝑠2 + 𝜎𝑤

2 ∼ 0.5

→ Score sensitivity dominates

Additionally, a rounding score was calculated to classify the considered technologies.

Rounding steps of 0.25 were defined. The highest point in Figure 78 shows that a maximum

of 10 technologies can be found with a score around 0.5. It is worth to point out that this

means 31% of the investigated technologies (10 out of 32).

FIGURE 78: GAUSSIAN DISTRIBUTION OF RANKED TECHNOLOGIES (SOURCE: JER)

Overall conclusion of the sensitivity analysis:

The estimated accuracy appears to be sufficient for this purpose

Most technologies get an overall score of about 0.5

A few technologies emerge as clear winners or loosers



4. SUMMARY

Responsible Author:


This Technolgy Roadmap has assessed a set of innovative renewable energy sources

(RES), storage and waste heat recovery technologies for efficient manufacturing in a factory

environment to reduce and improve the overall conventional energy demand of production

processes. Energy efficient hybrid systems are also assessed and described as combination

of RES and waste heat recovery technologies. The focus is on energetic solutions mainly

related to the hree industry sectors of the REEMAIN project.

Therefore, the road mapping exercise has produced a technology dataset or library of the

evaluated technologies. This includes an extensive list of available RES, storage, and waste

heat recovery technologies with a ranking of the most appropriate ones for the factory

environment (based on Strengths Weaknesses Opportunities and Threats (SWOT)

analyses including estimations on Live Cycle Costs (LCC), Live Cycle Assessment (LCA),

carbon reduction, Return On Investment (ROI), etc.). The dataset includes also a

comprehensive description of the evaluated innovative technologies with a short list of input

and output parameters as well as average variables.

In total 32 different technologies are described and ranked in this technology roadmap. The

highest achieved total score is 1.75 for the PV technology. Only thermal oil storage has been

ranked negative with a total score of -1.00. There are seven other technologies also with a

very low total score below 0.20. All the other technologies have total scores more ore less

above 0.50. The assessment of the sub-scores shows that 29 of 32 technologies have

positive technical scores. This means that from a technical point of view the screened and

described technologies are all technically feasible for the use and integration into

manufacturing processes. On the other hand, the economic scores show a different picture,

where 10 of 32 technologies (one third) have a negative score. This means, these

technologies are not economically feasible because of high investment costs and therefore

need incentives to be installed. The marketing of the various technologies is also valued

differently. 13 of 32 technologies have positive scores (good marketing to sell the

technologies), but the rest has either a neutral or a negative score (technologies are not well

known in the industry). The environmental scores show a very a nice picture, where all RES

and waste heat recovery technologies have high positive scores. On the other hand, three

of the 8 storage technologies have negative scores (thermal storage either with thermo oil,

concrete / rocks or cast iron / steel). Finally, four of the five energy efficient hybrid systems

have also negative environmental scores, if fossil fuels are used as energy source.



Furthermore, an additional benchmarking for six pre-selected innovative technologies (solar

concentrators, PV, solar cooling, CHPC, ORC, battery storage) was carried out based on a

survey. In total 14 feedbacks have been received from external reviewers/experts in the

different fields as well as 20 completed surveys from REEMAIN experts, which were almost

not involved in the preparation of the technology roadmap.

The following innovative technologies are finally identified through the assessment and

ranking within this Technology Roadmap for Efficient Manufacturing as highly interesting

technologies for manufacturing processes depending on different applications:

Cold generation Solar Cooling systems

Electricity generation Photovoltaic

Heat generation Solar Thermal Collectors and Solar Concentrators

Poly generation ORC and CHPC systems

Storage Hot Water Thermal Storage and

the Lithium-ion Battery



LIST OF FIGURES

Figure 1: Working principle of a flat plate collector (Source: JER) ................................. 4

Figure 2: Working principle of evacuated tube collector (Source: JER) ......................... 5

Figure 3: System scheme of a typical solar collector system (Source: Solera) .............. 6

Figure 4: Functional principle of Parabolic trough collectors (Source: Solera) ............... 9

Figure 5: Functional principle of linear fresnel collectors (Source: JER) ...................... 10

Figure 6: Functional principle of aircollectors (Source: Grammer Solar GmbH) .......... 13

Figure 7: Principle of a solar process heat system (Source: JER) ............................... 15

Figure 8: Solar industrial process heat plants – distribution by industry sector

(Source: JER; Database: AEE Intec) ............................................................ 17

Figure 9: Solar industrial process heat plants – Distribution by country (Source: JER;

Database: AEE Intec) ................................................................................... 17

Figure 10: Collector type of installed solar process heat systems (Source: JER;


Figure 11: Collector size of installed solar process heat systems (Source: JER;


Figure 12: System scheme of a solar cooling system – Closed system (Source: JER) . 20

Figure 13: System scheme of a photovoltaic system (Source: Solera) .......................... 24

Figure 14: Structure of PVT collectors (Source: Solimpeks) .......................................... 26

Figure 15: Principle solar concentration systems – absorber tube (Source: JER) ......... 28

Figure 16: Principle of solar concentration systems – central receiver (Source: JER) ... 29

Figure 17: Basic electricity production scheme with parabolic collectors

(Source: Solera) ............................................................................................ 30

Figure 18: Basic electricity production scheme with linear Fresnel collectors

(Source: Solera) ............................................................................................ 30

Figure 19: HAWT and VAWT schemes (Source: JER) .................................................. 33

Figure 20: Construction of wind turbine (Source: Alstom) .............................................. 34

Figure 21: Different turbine types (Source: Alstom) ....................................................... 37

Figure 22: Hydropower is related to flow rate and head

(Source: Engineeringtoolbox) ....................................................................... 38

Figure 23: Relatively high cost of small hydropower schemes

(Source: renewablesfirst.co.uk) .................................................................... 40

Figure 24: Principle of low temperature geothermal system (Sources: JER) ................. 43

Figure 25: Working conditions of geothermal systems for heating and cooling

(Source: Caleffi) ............................................................................................ 43

Figure 26: Biomass boiler scheme (Source: wellonsfei.ca)............................................ 48

Figure 27: Biomass gasifier scheme (Source: Dockside Green, Victoria Canada) ........ 48

Figure 28: System scheme of a CHP plant with biogas as fueL

(Source: ZORG-Biogas.com) ........................................................................ 54

Figure 29: Scheme of a biomass cogeneration system (Source: Cartif) ........................ 61

Figure 30: Principle of a Thermal energy Storage (Source: JER) .................................. 67



Figure 31: Scheme of a steam accumulator – Ruths storage (Source: DLR) ................ 68

Figure 32: Simplified scheme of a solar thermal power plant with direct steam

generation (DSG) and integrated steam accumulator (Source: DLR) ........... 69

Figure 33: Process scheme of a solar energy generation plant with a direct two-tank

thermal oil storage system (Source: JER) .................................................... 69

Figure 34: Oil plus rocks passive storage system (Source: power from the sun.net) ..... 71

Figure 35: Process schematic of a solar energy generation plant with a concrete TES

(Source: W. D. Steinmann, M. Eck) .............................................................. 71

Figure 36: Schematic representation of a cast steel sensible heat storage system

(Source: JER) ............................................................................................... 72

Figure 37: Pictures of aN ice-storage (Source: Solera) ................................................. 78

Figure 38: Scheme of a solar cooling system with a latent heat storage

(Source: Solera) ............................................................................................ 79

Figure 39: Classes of materials that can be used as PCM and their typical range of

melting temperature and melting enthalpy (Source: ZAE BAYERN)............. 82

Figure 40: PCM classification (Source: JER) ................................................................. 82

Figure 41: Schematic representation of the integration of a Battery together with a PV

system on a Factory level / DC-Coupling (Source: Ikerlan) .......................... 86

Figure 42: Schematic representation of the integration of a Battery together with a PV

system on a Factory level / AC-Coupling (Source: Ikerlan) .......................... 87

Figure 43: Diagram of possible applications of orc according to the energy source

(Source: CARTIF) ......................................................................................... 89

Figure 44: ORC integrated with a biomass boiler (Source: Turboden) .......................... 90

Figure 45: Schematics of absorption A) and adsorption B) chillers (Source: JER) ........ 93

Figure 46: Typical sources, cold distribution systems and heat rejection sinks for a

TDHP system (Source: EURAC) .................................................................. 95

Figure 47: Functional principle of a heat exchanger (Source: JER) ............................... 98

Figure 48: Electric motor-driven vapour compression heat pump (Source: JER) ........ 101

Figure 49: A) Electrical driven heat pump; B) Absorption heat pump (Source: JER) ... 102

Figure 50: Market available WHP systems (Source: Ergion) ....................................... 107

Figure 51: Scheme of a WHP system only for pressure reduction (Source: JER) ....... 108

Figure 52: Scheme of a WHP system including additional Waste heat input

(Source: JER) ............................................................................................. 109

Figure 53: Scheme of CHP systems integrated to industry. gas turbines or gas/oil

engine (Source: IESO) ................................................................................ 112

Figure 54: Schemes of CHP systems integrated to industry. Through steam turbines

(Source: IESO) ........................................................................................... 113

Figure 55: PEM Technology scheme for CHP (Source: JER) ...................................... 118

Figure 56: General CHP fuel cell system (Source: Energy solution center) ................. 119

Figure 57: System scheme of a CHPC system (Source: JER) .................................... 122

Figure 58: Layout of a DH system with heat storage (Source: Ramboll Energy) ......... 124

Figure 59: Total scores of technology ranking for classification clusters

(Source: JER) ............................................................................................. 141



Figure 60: Single scores of technology ranking (technical, economic, marekting and

environmental) (Source: JER)..................................................................... 141

Figure 61: Total scores of technology ranking for generation clusters (Source: JER) . 142

Figure 62: Total scores of technology ranking for Cold generation clusters

(Source: JER) ............................................................................................. 144

Figure 63: Total scores of technology ranking for Electricity generation clusters

(Source: JER) ............................................................................................. 144

Figure 64: Total scores of technology ranking for Heat generation clusters

(Source: JER) ............................................................................................. 144

Figure 65: Total scores of technology ranking for Poly-generation clusters

(Source: JER) ............................................................................................. 145

Figure 66: Total scores of technology ranking for storage clusters (Source: JER) ...... 145

Figure 67: Total / Sub-score comparision of solar concentrator technology ranking

(Source: JER) ............................................................................................. 147

Figure 68: Total / Sub-score comparision of PV technology ranking (Source: JER) .... 148

Figure 69: Total / Sub-score comparision of solar Cooling technology ranking

(Source: JER) ............................................................................................. 148

Figure 70: Total / Sub-score comparision of CHPC technology ranking

(Source: JER) ............................................................................................. 148

Figure 71: Total / Sub-score comparision of ORC technology ranking (Source: JER) . 149

Figure 72: Total / Sub-score comparision of Battery storage technology ranking

(Source: JER) ............................................................................................. 149

Figure 73: Comparison of different alternatives, cold cluster (Source: JER) ................ 151

Figure 74: Comparison of different alternatives, electricity cluster (Source: JER) ....... 152

Figure 75: Comparison of different alternatives, heat cluster (Source: JER) ............... 152

Figure 76: Comparison of different alternatives, cold cluster (Source: JER) ................ 153

Figure 77: Comparison of different alternatives, storage cluster (Source: JER) .......... 153

Figure 78: Gaussian distribution of ranked technologies (Source: JER) ...................... 154



LIST OF TABLES

Table 1: Technologies in proposed clusters (Source: JER) .......................................... 2

Table 2: Main inputs, outputs and general parameters for flat plate collectors ............. 4

Table 3: Main inputs, outputs and general parameters for evacuated tube collectors .. 6

Table 4: SWOT analysis for low temerature collectors – Technical Aspects ................ 7

Table 5: SWOT analysis for low temerature collectors – Costs, Marketing and

Ecology ........................................................................................................... 7

Table 6: Main inputs, outputs and general parameters for parabolic trough collectors . 9

Table 7: Main inputs, outputs and general parameters for linear fresnel collectors .... 10

Table 8: SWOT Analysis for tracked Concentrating collectors for medium

temperatures – Technical Aspects ................................................................ 11

Table 9: SWOT Analysis for tracked Concentrating collectors for medium

temperatures – Costs, Marketing and Ecologoy ........................................... 12

Table 10: Main inputs, outputs and general parameters for air collectors .................... 14

Table 11: SWOT Analysis for Air collectors – Technical Aspects ................................. 14

Table 12: SWOT Analysis for Air collectors – Costs, Marketing and Ecology ............... 14

Table 13 Industrial sectors and processes with its temperature level [4] ..................... 16

Table 14: Main inputs, outputs and general parameters for solar cooling systems ...... 21

Table 15: SWOT Analysis of solar cooling systems – Technical Aspects .................... 21

Table 16: SWOT Analysis of solar cooling systems – Costs, Marketing and Ecology .. 22

Table 17: Main inputs, outputs and general parameters for photovoltaik modules ....... 24

Table 18: SWOT Analysis for Photovoltaik modules – Technical Aspects ................... 24

Table 19: SWOT Analysis for Photovoltaik modules – Costs, Marketing and Ecology . 25

Table 20: Main inputs, outputs and general parameters for photovoltaik thermal

collectors ...................................................................................................... 27

Table 21: SWOT analysis for photovoltaik thermal systems – Technical Aspects ........ 27

Table 22: SWOT analysis for photovoltaik thermal systems – Costs, Marketing and

Ecology ......................................................................................................... 27

Table 23: Main inputs, outputs and general parameters for parabolic trough- and

fresnel collectors ........................................................................................... 31

Table 24: SWOT analysis of concentrated solar power systems – Technical Aspects . 31

Table 25: SWOT analysis of concentrated solar power systems – Costs, Marketing and

Ecology ......................................................................................................... 32

Table 26: Main inputs, outputs and general parameters for wind turbines ................... 35

Table 27: SWOT analysis of wind turbine systems – Technical Aspects ...................... 36

Table 28: SWOT analysis of wind turbine systems – Costs, Marketing and Ecology ... 36

Table 29: Application and performance range of different turbines [11] ....................... 39

Table 30: Main inputs, outputs and general parameters for hydro electricity ................ 40

Table 31: SWOT analysis of hydro power systems – Technical Aspects ..................... 40

Table 32: SWOT analysis of hydro power systems – Costs, Marketing and Ecology ... 41

Table 33: Main inputs, outputs and general parameters for geothermal ....................... 45



Table 34: SWOT Analysis of geothermal systems – Technical Aspects ....................... 45

Table 35: SWOT Analysis of geothermal systems – Costs, Marketing and Ecology .... 46

Table 36: Types of gasifiers with their characteristic parameters [13] .......................... 49

Table 37: Main parameters according to power generation technology that use biomass

fuels systems ................................................................................................ 50

Table 38: Main inputs, outputs and general parameters for Biomass Combustion

systems ........................................................................................................ 50

Table 39: Main inputs, outputs and general parameters for Biomass Gasification

systems ........................................................................................................ 51

Table 40: SWOT Analysis of biomass heating systems – Technical Aspects............... 51

Table 41: SWOT Analysis of biomass heating systems – Costs, Marketing and

Ecology ......................................................................................................... 52

Table 42: Main parameters according to power generation technology that use

biogas ........................................................................................................... 56

Table 43: Main inputs, outputs and general parameters for Biogas CHP systems ....... 56

Table 44: SWOT Analysis for biogas chp units – Technical Aspects ............................ 57

Table 45: SWOT Analysis for biogas chp units – Costs, Marketing and Ecology ......... 58

Table 46: Main parameters according to power generation technology that can use

biomass as fuel ............................................................................................. 62

Table 47: Main inputs, outputs and general parameters for Biomass CHP systems .... 63

Table 48: SWOT Analysis for solid biomass chp units – Technical Aspects................. 63

Table 49: SWOT Analysis for solid biomass chp units – Costs, Marketing and

Ecology ......................................................................................................... 64

Table 50: Sensible heat thermal storage materials with corresponding working

temperature ranges ...................................................................................... 66

Table 51: Characteristic parameters for a hot water TES system ................................. 67

Table 52: Characteristics of thermal oils for TES systems............................................ 70

Table 53: Characteristics of rocks and concrete TES systems ..................................... 71

Table 54: Characteristics of cast iron / steel for TES systems ...................................... 72

Table 55: SWOT Analysis for Cold / Hot water storages – Technical Aspects ............. 73

Table 56: SWOT Analysis for Cold / Hot water storages – Costs, Marketing and

Ecology ......................................................................................................... 73

Table 57: SWOT Analysis for Steam Storages – Technical Aspects ............................ 74

Table 58: SWOT Analysis for Steam Storages – Costs, Marketing and Ecology ......... 74

Table 59: SWOT Analysis for Oil storages – Technical Aspects .................................. 75

Table 60: SWOT Analysis for Oil storages – Costs, Marketing and Ecology ................ 75

Table 61: SWOT Analysis for Concrete / Rock Bed storages – Technical Aspects ...... 76

Table 62: SWOT Analysis for Concrete / Rock Bed storages – Costs, Marketing and

Ecology ......................................................................................................... 76

Table 63: SWOT Analysis for Cast iron / steel storages – Technical Aspects .............. 77

Table 64: SWOT Analysis for Cast iron / steel storages – Costs, Marketing and

Ecology ......................................................................................................... 77

Table 65: Transition temperature and heat of latent heat subtances [26] ..................... 78



Table 66: Main inputs, outputs and general parameters for ice storages ..................... 79

Table 67: SWOT Analysis for ice storages – Technical Aspects .................................. 80

Table 68: SWOT Analysis for ice storages – Costs, Marketing and Ecology ................ 80

Table 69: Characteristics of PCM Storage.................................................................... 81

Table 70: Main inputs, outputs and general parameters for PCM storages .................. 83

Table 71: SWOT Analysis for PCM storages – Technical Aspects ............................... 83

Table 72: SWOT Analysis for PCM storages – Costs, Marketing and Ecology ............ 84

Table 73: Main inputs, outputs and general parameters for Battery storages ............... 87

Table 74: SWOT Analysis for Batterie storages – Technical Aspects .......................... 88

Table 75: SWOT Analysis for Batterie storages – Costs, Marketing and Ecology ........ 88

Table 76: Main inputs, outputs and general parameters for ORC systems................... 90

Table 77: SWOT Analysis of ORC systems – Technical Aspects ................................. 91

Table 78: SWOT Analysis of ORC systems – Costs, Marketing and Ecology .............. 92

Table 79: Operating parameters for different types of TDHP for cooling

applications [32] ............................................................................................ 96

Table 80: Main inputs, outputs and general parameters for thermal cooling ................ 96

Table 81: SWOT Analysis for thermal cooling – Technical Aspects ............................. 97

Table 82: SWOT Analysis for thermal cooling – Costs, Marketing and Ecology ........... 97

Table 83: Main inputs, outputs and general parameters for heat exchanger systems .. 99

Table 84: SWOT Analysis for heat exchangers – Technical Aspects ......................... 100

Table 85: SWOT Analysis for heat exchangers – Costs, Marketing and Ecology ....... 100

Table 86: Operating parameters for different types of heat pumps ............................. 104

Table 87: Technology and typical costs of heat pumps for residential space heating,

cooling and hot water supply of single-family houses [34] .......................... 104

Table 88: Main inputs, outputs and general parameters for heat pumps .................... 105

Table 89: SWOT Analysis for heat pumps – Technical Aspects ................................. 105

Table 90: SWOT Analysis for heat pumps – Costs, Marketing and Ecology .............. 106

Table 91: Main inputs, outputs and general parameters for WHP systems ................ 109

Table 92: SWOT Analysis for WHP systems – Technical Aspects ............................. 109

Table 93: SWOT Analysis for WHP systems – Costs, Marketing and Ecology ........... 110

Table 94: Main parameters according to power generation technology that use fossil

fuels in CHP systems .................................................................................. 114

Table 95: Main inputs, outputs and general parameters for CHP systems ................. 114

Table 96: SWOT Analysis for gas and oil CHP units – Technical Aspects ................. 115

Table 97: SWOT Analysis for gas and oil CHP units – Costs, Marketing and

Ecology ....................................................................................................... 116

Table 98: Main inputs, outputs and general parameters for CHP systems ................. 117

Table 99: Commercial PAFC [35] and MCFC solutions [36] ....................................... 119

Table 100: Main inputs, outputs and general parameters for fuel cell CHP systems .... 120

Table 101: SWOT Analysis for fuel cell CHP units – Technical Aspects ...................... 120

Table 102: SWOT Analysis for fuel cell CHP units – Costs, Marketing and Ecology .... 121

Table 103: Main inputs, outputs and general parameters for CHPC systems .............. 123

Table 104: SWOT Analysis for CHPC systems – Technical Aspects ........................... 123



Table 105: SWOT Analysis for CHPC systems – Costs, Marketing and Ecology ......... 123

Table 106: Main inputs, outputs and general parameters for district heating................ 127

Table 107: SWOT Analysis of direct heating systems – Technical Aspects ................. 128

Table 108: SWOT Analysis of direct heating systems – Costs, Marketing and

Ecology ....................................................................................................... 128

Table 109: Main inputs, outputs and general parameters for district cooling ................ 130

Table 110: SWOT Analysis of direct cooling systems – Technical Aspects.................. 131

Table 111: SWOT Analysis of direct cooling systems – Costs, Marketing and

Ecology ....................................................................................................... 131

Table 112: Factor and grouping for Ranking matrix (Source: EURAC, JER) ................ 135

Table 113: Technology ranking for classifcation clusters (Source: JER) ...................... 140

Table 114: Technology ranking for Generation clusters ............................................... 143

Table 115: Weight factors for the sensitivity analysis ................................................... 150



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