Solar District Heating with Seasonal Thermal Energy...

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Solar District Heating with Seasonal Thermal Energy Storage in Germany

Steinbeis Research Institute

Dipl.-Ing. Thomas Pauschinger

esea c st tutefor Solar and Sustainable Thermal Energy Systemswww.solites.de

Meitnerstr. 870563 Stuttgart, Germanywww.solites.de

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Solar District Heating with Seasonal Thermal Energy Storage

• Introduction

• National research programmes

• Pilot plants

Steinbeis Research Institute for Solar and Sustainable Thermal Energy Systemswww.solites.de

Solites - Steinbeis Research Institute for Solar and SustainableThermal Energy Systems

Member of the Steinbeis Foundation:

• turnover in 2010 over 100 Mio Euro

• technology transfer, consultancy and research

• Concept- and project development of sustainable energy supply systems(heat, cold and electricity, high reduction of CO2-emissions)

• Comprehensive energy concepts for buildings (adjustment of architectural concept, thermal insulation, building services and RES)

• Advisor to different ministries and international organisations (IEA/ OECD, EU, GER)(R&D for large scale solar thermal systems, STES and RES)

• Surveyor for large scale solar thermal systems with STES


Surveyor for large scale solar thermal systems with STES

• Chairman of the German experts group on seasonal thermal energy Storage

• Member of several international experts groups(R&D for large scale solar thermal systems, STES and RES)

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Background of scientific R+D

• 1992 – 2003: Solarthermie-2000 – Part 3

part 3: Central Solar Heating Plants with Seasonal Storage (CSHPSS)

• Development of seasonal storage concepts• Realisation of eight pilot plants

• 2004 - 2008: Solarthermie2000plus

one central point: Seasonal Thermal Energy Storage (STES) for:

• solar • waste heat• cooling• combined heating & cooling• CHP, biomass• etc.


etc.

• Since 2009: R+D programme for solar thermal systems and storages

-> Fundamental: Funding of ca. 50 % of investment costs for solar system

System concept of a central solar heating plant with seasonal storage

Solar collectors

Target: solar fraction of total heat demand: 50 %

Central heating plant


Seasonalthermal energy storage (STES)

District heating network

Solar network

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CSHPSS in Hamburg, 1996


(Source: Gockell)

Solar fractions of solar thermal systems 7 – 10 %

Solar fraction:

15 – 20 %

~ 50 %

Hea

t am

ount Solar irradiation

Total heat demand


Central Solar Heating Plant with

Seasonal StorageDomestic hot water system (100 % solar in summer)

Combisystem (hot water and space heating)

Jan AprFeb Mar May June July OctSepAug Nov Dec

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Seasonal Thermal Energy Storage (STES) – Concepts

Pit thermal energy storage (PTES)(60 to 80 kWh/m³)

Tank thermal energy storage (TTES)(60 to 80 kWh/m³)

Pit thermal energy storage (PTES)(60 to 80 kWh/m³)

Tank thermal energy storage (TTES)(60 to 80 kWh/m³)

Borehole thermal energy storage (BTES) Aquifer thermal energy storage (ATES)(30 to 40 kWh/m³)(15 to 30 kWh/m³)

Borehole thermal energy storage (BTES) Aquifer thermal energy storage (ATES)(30 to 40 kWh/m³)(15 to 30 kWh/m³)


Hamburg (1996)

3.000 m² FPC

4.500 m³

Tank

Friedrichshafen

(1996)4.050 m² FPC12.000 m³Tank

The pilot plants from the programs Solarthermie-2000 / 2000plus (1)

Neckarsulm (1997)5.300 m² FPC63.300 m³ BTES

Steinfurt (1998)510 m² FPC1.500 m³ Pit

Rostock (2000) Hannover (2000)


1.000 m² FPC20.000 m³ ATES

1.350 m² FPC2.750 m³ Tank

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Chemnitz, 1st CS

(2000)

540 m² VTC

8.000 m³Pit

Attenkirchen (2002)

800 m² FPC500 + 9.350 m³Tank + BTES

The pilot plants from the programs Solarthermie-2000 / 2000plus (2)

Pit

Munich (2007)2.900 m² FPC5.700 m³Tank

Eggenstein (2008)

Crailsheim (2008)5.300 m² FPC100 m³ + 480 m³Buffer Tanks37.500 m³BTES


1.600 m² FPC

4.500 m³Pit

The CSHPSS in Munich: installation of solar collectors, 2007

Start of operation: 2007

24.800 m² heated area (2.300 MWh/a)

2 900 m² solar collectors


2.900 m solar collectors

5.700 m³ tank

Solar fraction: 47 %*

*simulation results ZAE

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Construction of the seasonal heat storage in Munich , 5.700 m³, 2007


Munich - Buildings

• Solarisation of development scheme:

• south-orientation of buildings with solar collectors

• building distances and heights optimised with respect to shading effects

20° f l f b ildi ith l ll t• 20° roof slope of buildings with solar collectors

• intersected collector fields for better illumination of roof apartments

• Requirements on building companies:

• limitation for heat demand (60 kWh/m²a)

• low-temperature heating systems (max. 55/30 °C supply/return at design conditions)


• apartment transfer substations for heat delivery

• strong requirements for return temperatures (max. 30 °C)

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Solar district heating with pit storage in Eggenstein, 2008


school, sports center from 1970sall energetically renovatedconstruction of solar system: 2008

12.000 m² heated area (1.150 MWh/a)1.600 m² solar collectors4.500 m³ pit storagesolar fraction (design): 37 %

Pit storage in Eggenstein, 4.500 m³, 2008


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Concept of the pit storage in Eggenstein, 4.500 m³

foam glass gravel

gravel

sand

fleece

HDPE liner

fleece

compound liner with vapour barrier

expanded glass granules

gravel

well1m 70cm


gravel

50cm

sand

The CSHPSS in Crailsheim


service area: 260 apartments, school, gym.heat demand: 4.100 MWh/yearsolar collectors:7.300 m² (aperture) buffer storage: 100 + 480 m³ (water tank)

STES: 37.500 m³ (BTES)el. heat pump: 530 kWsolar fraction: 50 % (design)solar heat cost: 19 Euro-Cent/kWh

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Solar collector fields in Crailsheim

(Source: Stadtwerke Crailsheim)


BTES in Crailsheim, 37.500 m³, 2008


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BTES in Crailsheim

No. of Boreholes: 80Depth: 55 mVolume: 37.500 m³BHE: 2xU (PEX)Insulation: 40 cm foam

Gras

SoilProtective foil

Gras

Drainage

Foam glass gravel

(to the surface) glass gravel

Thermally reducedgrouting

Casing

Double U-pipeborehole heat

exchanger (BHE)

Layer withinter-mittentstratumwater

4 m

Lime-

GOK


Thermallyenhancedgrouting

stone

System and solar heat cost for solar thermal systems

700

800

900

1000

m² F

P]

0.35

0.40

0.45

0.50

€/kW

h]

Cost basis 2005

0

100

200

300

400

500

600

Sys

tem

co

st [

€/m

0 00

0.05

0.10

0.15

0.20

0.25

0.30

So

lar

hea

t co

st [

€


0

Small DHW System

AColl < 10 m²fsol ≈ 7-15%

Small Combi-system

AColl < 20 m² fsol ≈ 12-20%

Large DHW System

AColl ≈ 100 m²fsol ≈ 3-10%

Large Combi-system

AColl ≈ 200 m²fsol ≈ 15-20%

CSHPSSAColl ≈ 5000 m²

fsol ≈ 50%

0.00

DHW: domestic hot water, AColl: solar collector area; fsol: solar fraction; CSHPS/DS: Central Solar Heating Plant with Seasonal/Diurnal Storage

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Investment cost of seasonal thermal energy storages

350

400

450

500v

ale

nt

[€/m

³]

realisedstudyTanksPitsBTESATES

Rottweil

Steinfurt

Ilmenau Crailsheim

100

150

200

250

300

350

nv

estm

en

t c

ost

per

m³

wa

ter

equ

iv

Neckarsulm

Stuttgart

Hamburg

Friedrichshafen (HW)

Berlin-Biesdorf

Chemnitz

Bielefeld

Hanover

Kettmann-hausen

MunichEggenstein


0

50

100 1,000 10,000 100,000

In

Storage volume in water equivalent [m³]

(1. phase) Potsdam

RostockCrailsheim

Outlook: R&D-targets for STES

• Materials and wall constructions for combined thermal and pressure stress (>100 °C water / steam)

• Two fields of developments:

• Large scale storages above 1.000 m³

• Buffer storages between 100 und 500 m³.

• Improved reliability of storages

• Multi-functionality (heat sources, long-term / short-term etc.)

• Optimisation on total system level

• Comprehensive design and realisation process


Target 2020: The first technologies of seasonal thermal energy storage for high solar fractions and excess heat storage are ready for the market.

Solar District Heating with Seasonal Thermal Energy...

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