Renewable Energy Sources

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Introduction to Energy Science and Energy Technology, Renewables and Conventionals

• What is Energy ?-Energy, Exergy, Anergy-Forms of Energy-Various Sciences and Energy Science-Energy Technology-Energy, Man and Environment-Law of Conservation of Energy-Thermodynamics and Energy Analysis -First and Second Laws of Thermodynamics.

• Energy chains and Energy Links- Energy Resources-Primary Energy -Intermediate Energy-Usable (Secondary) Energy -Energy Calculations-Units and Conversion Factors.

• Conventional, Renewable, Non-conventional and Alternate Sources of Energy. Energy Demand - Energy Requirements by various sectors-Energy Routes of conventional energy-Renewable Energy. Wind Energy-Solar Energy -Biomass Energy-Energy from Ocean-Geothermal Energy-Changing Energy Consumption trends.

• Electrical Energy - Load curves-Peak Load/Base Load, Generating Units-Energy Storage Plants. Energy

• Supply System in India - Coal and Coal Technologies-Petroleum and Natural Gas-Nuclear Fuels and Power Plants-Hydro Resources and Power Plants-Energy Strategies-Energy Conservation-Energy Audit-Cost of energy-Scope of subject - Summary - Questions.

Energy is the capability to produce motion; force, work; change in shape, change in form, etc.

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What is Energy?

The concept drawn from classical physics while explaining work

Energy exists in several forms. Energy transformations are responsible for various activities

.

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Hydrogen energy conversion paths

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Energy exists in many forms such as • chemical energy (Ech), • nuclear energy (Enu), • solar energy (Eso), • mechanical Energy (Eme)• electrical energy (Eec), • internal energy in a body (Ein),• bio-energy in vegetables and animal bodies (Ebi), • thermal energy Eth, etc.

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coal, petroleum, solar, wind, geothermal, etc

steam, chemicalsfuels, electricity etc

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Energy Technology? distinguish between 'Energy' 'Useful Energy' and Worthless Energy' with reference to useful work content.

Energy Science

Science is a systematized body of knowledge about any department of nature, internal or external to man.

The energy science deals with scientific principles, characteristics, laws, rules, units/dimensions, measurements, processes etc. about various forms of energy and energy transformations.

Science involves experimentation, measurement, mathematical calculations, laws, observations, etc.

Energy Technology

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concerned with 'demand' for various forms of secondary energy (usable energy) and the methods of 'supply‘

various alternative routes. deal with plants and processes

involved in the energy transformation and analysis of the useful energy (exergy) and worthless energy (anergy). Energy Technology includes study of efficiencies and environmental aspects of various processes.

The applied part of energy sciences for work and processes, useful to human society, nations and individuals is called Energy Technology. Energy technologies deal with various primary energies, processing, useful energies and associated plants and processes. The coverage including exploration, transportation, conversion, utilization.

Mother Science

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Energy science has interface with every other science. Energy science is the mother science of physics, thermodynamics, electromagnetic, nuclear science, mechanical science, chemical science, bio sciences etc. Each science deals with some 'activity'. Energy is the essence of activities.

Energy technology deals with the complete energy route and its steps such as :

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- Exploration of energy resources- Discovery of new sources - Extraction or Tapping of Renewable or Growing of Bio-farms - Processing - Intermediate storage -Transportation/Transmission - Reprocessing - Intermediate storage - Distribution -Supply - Utilization.

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Energy Strategies include

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long term policies, short-term and Mid-Term

Planning, Economic planning, Social and Environmental Aspects

of various energy routes.

These are analyzed from the perspectives of the world, Region, Nation, States, sub-regions, various economic sectors, communities and individuals

Energy Science and Energy Technology is of immense interest to the Planers, Economists, Scientists, Engineers, Professionals and Industrialists, Societies and Individuals, etc.

Various Sciences and Energy Science

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Physics : It is a branch of natural science dealing with properties and changes in matter and energy. Physics deals with continuous changes in matter and energy and includes mechanics, electromagnetic, heat, optics, nuclear energy etc. and laws governing the energy transformations. Energy science has been developed by Physicists.

Thermodynamics : It is a branch of physics dealing with trans formation of thermal energy into other forms of energy, espe6ially mechanical energy and laws governing the conversions. Ther­modynamics­plays a dominant role in Energy Technologies.

Biological Sciences deal with biomass and biological processes.

Bio sciences are concerned with the physical characteristics,' life processes of living vegetation and animals on land and in water and their remains.

Biomass­is the matter derived from vegetation and nimals. Biomass­is­a­natural­renewable­source­of­energy­and is being given highest priority in recent years. (1980s onwards) Biomass is the important renewable energy for the 21st century.

Chemistry­is a science dealing with composition and properties of substances and their reactions­to form other substances. The chemical reactions are accompanied by release of thermal energy (exothermic reactions) or absorption of thermal energy (endothermic reaction). Chemical­Reactions­are intermediate energy conversion processes.

Many useable energy forms are obtained from chemical reactions. (e.g.­petroleum products, synthetic gases and liquids). Natural­Gas­and­Petroleum­products are most important energy forms in the world during 20th and 21st century.

Electromagnetic : The flow of electrons and electrical charges through a circuit produces associated electromagnetic fields and electrical energy. Electromagnetic is a branch of physics dealing with electricity, magnetism and various transformations of ·other forms of energy (mechanical, thermal, chemical etc.) into electrical I energy and vice-versa.­Electrical­energy­is­the­most­superior;­efficient,­useful­form­of­energy­which­can­be­generated,­transmitted,­distributed,­controlled,­utilized.­Electrical­energy­is­an­intermediate­and­secondary­form­of­energy­being­used­very­widely­all­over­the­world.­

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Science : Finally figured out

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Energy science and other sciences are co-related

Energy Technology and Energy Sciences

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Energy Science and Technology deal with several useful natural and artificial (man-made) energy systems. The basic objectives are to extract, convert, transform, transport, distribute and reconvert different types of energy with least pollution and with highest economy.

Energy technology is a systematized knowledge of various branches of energy flow and their relationship with human society as viewed from scientific, economic, social, technological, industrial aspects for benefit of man and environment.

Science of energy is concerned with the natural rules and characteristics of energy, energy resources, energy conversion processes and various phenomena related directly or indirectly to the extraction conversion and use of energy resources essential to the economy and prosperity.

Science of energy deals with the phenomena related with energy conversion plants and processes for generating secondary energy (electricity, heat, steam, fuel, gas, etc.) by converting various kinds of primary energy sources. It also deals with aspects of useful energy, (exergy), work, power, efficiency and worthless energy (anergy) losses etc.

Energy, Man and Environment

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Close liason between Energy, Energy Conversion Processes, Man and Environment.

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Renewables & Non-conventionals Renewables

Conventional & Non-conventionals

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Renewables are those which are renewed by the nature again and again and their supply is not affected by rate of consumption

Sources: solar, wind, geothermal, ocean thermal, ocean wave, ocean tide, mini-hydro, bio-mass, chemicals, waste fuels etc. These are available from nature in renewable but periodic/intermittent form.

Global Status: Renewables in the world is less than 2% (excluding hydro). This is likely to increase to about 10% by 2000 AD and to about 15% by 2015· AD.

Merits & Demerits: Renewables are cheap, clean energy resources. However, solar and wind sources are intermittent, diffused and their conversion technologies are presently costly and suitable only of smaller plant capacities.

Energy resources which are in use during 1950-1975 are called conventionals.

Energy resources which are considered for large-scale use after 1973 oil crisis are called Non-conventional or Alternate.

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Renewables and Non-conventionals

Feature Conventional/ Nonrenewable

Renewables

- Technologies Established Under development

- Plant size Large (MW range) Small (kW range)

- Main Power Plants Suitable Not sufficient

- Energy density of source High Low

- Pollution problems More Less

- Energy reserves Limited Will continue to renew

- Cost of generation Low High

-Storage Easy Uneconomical

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Conventional and Renewable Resources for Electrical Generation

Conventional Alternative, Renewable*Coal Wind power

Petroleum oils Solar power

Natural Gas Geothermal

Hydro Ocean waves

Nuclear fission fuels Ocean tide

Fire-wood Bio-mass fuels

Waste-fuels

Bio-gas

Synthetic gases

Nuclear fusion fuels+

Fuels for fuel cells

Firewood*

Ocean-algae fuel

Ocean salinity gradient+

*Considered on priority after 1973 oil crisis.

+ Not yet on commercial scale. *For power plants

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Non-renewable energy resources can not be get replenished after their consumption. e.g. coal once burnt is consumed without replacement of the same (Fossil fuels, Nuclear fission fuels).

The energy resources which are formed very slowly in nature and which are likely to be exhausted in a few more decades or centuries are called Non-renewable. World is presently dependant on such resources (90% supplies of world primary resources are by Non renewables-1990)

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Energy Demand

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Rising rapidly with growing population and industrialization.

Secondary (usable) energy forms of importance are :

- Fuels: Coal, petroleum (Oil), Natural Gas, Chemicals, Fire- wood etc.

- Electrical power

- Chemicals for processes.

- Renewables such as solar heat, bio-gas, wind, bio-mass etc.

Energy in various secondary (usable) forms for various activities.

- Domestic, Social, Municipal - Agriculture

- Commercial

- Industrial

- Transportation

- Defence, Medical, Scientific work etc.

Increasing demand of primary energy resources in India

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Total annual primary energy consumption between 1994 and 2004. Key: kWh, kiloWatt hours.

Source: US Dept of Energy Information Administration

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World consumption of primary energy by fuel type between 1994 and 2004. Key: GSWW, geothermal, solar, wind and wood/waste; kWh, kiloWatt hours

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Energy consumption per capita in 1994 and 2004, by region. Total is the average global energy use per capita. Key: kWh, kiloWatt hours

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Increase in primary energy consumption per capita between 1994 and 2004. Total is the average global increase, per capita, over the period.

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Carbon dioxide emissions from fossil fuel consumption, in 1994 and 2004, by region

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Percentage increase in carbon dioxide emissions from fossil fuel consumption, between 1994 and 2004, by region. Note: emissions in Eurasia actually fell slightly. Total is the average global increase over the period.

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Projected increase in primary energy consumption from 2003 to 2030, by energy type. Key: energy "other" in this case is hydroelectricity together with renewables (GSWW); kWh, kiloWatt hours

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Projected percent increase in primary energy consumption from 2003 to 2030, by energy type. Key: energy "other" in this case is hydroelectricity together with renewables (GSWW)

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The higher the demand for primary energy is in a country, the higher is its gross domestic product and therefore the  (measurable) standard of living.

The cycle consisting of the gross domestic product and the demand for primary energy, which determines the standard of living.

Correlation between the gross domestic product and the demand for primary energy of selected countries in 2000

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During past several decades, the energy demand of the world has continued to increase at an annual growth rate of 3 to 4% due to the following reasons:

- Increasing per capita energy consumption with increasing standard of living.

- Increasing population.

- Increasing industrialization.

-Invention of large energy conversion machines. (Electric motors, gas turbines internal combustion engines etc.

- Increasing transportation.

- Development of energy supply systems and availability of electrical energy and fuels.

Energy needs of man vary with life-style, climatic conditions, season, industrial progress etc.

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Industry needs coal, steam, electrical energy, furnace oils, diesel, chemicals, lubricating oils etc. Raw materials, like steel, copper, aluminum, etc. are produced by energy-intensive processes. Water is pumped and distributed by using motor-pumps which consume electrical energy. Transportation by road, rail, ocean and air requires high energy input.

Higher per capita energy consumption of a country indicates industrial progress and prosperity. For example, the annual per capita electrical energy consumption of India in 1988 was 2388 kWh against 92,000 kWh of USA.

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Historical Review of Growing Energy Demand of Man

Daily per capita Energy Consumption, kWh per day, per capita

Historical age Food Agriculture Domestic Industry Transport Total

-Cave Man (10,00,000 years ago)

3 3

-Hunting Man (1,00,00 years ago) 4 3 7

- Agricultural Man (5000 BC) 5 2 6 13

-Industrial Man- (20th Century) 10 5 60 100 85 260

- Technologically advanced man (21st Century)

10 5 60 150 185 410

1 kWh = 1 kilo-watt hour = 1000 Watt. hour = 3.6 x 106 J

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India’s electrical power plants: India's demand for electrical energy is growing at an annual increase by 8 to 10%.

Conventional Relative use % Non conventional

Renewable

Relative use %

1. Coal Fired Steam Thermal 68 1. Wind-power

2. Hydro-electric Plants 25 2. Solar power

3. Nuclear Plants 5 3. Geothermal

4. Gas-Turbine Plants 4. Ocean-Thermal

5. Combined Cycle 2 5. Ocean-waves

-Gas 6. Waste incineration

-Steam 7. Biomass

8. Fuel cells

6. Cogeneration Plants 1 9. Nuclear Fusion

-Heat 10. Others

-Steam Total <1% - Electricity

7. Renewable 1

Age of Renewables and Alternatives

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Fossil Fuel age is expected to span only 1000 years of human civilization (1700 AD to 2700 AD).

The prices of petroleum are increasing.

Environmental imbalance created by combustion of coal; nuclear waste deposits, deforestation by hydro power plants etc.

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Some alternate energy power plants have been built on commercial basis in several advanced countries. Developing countries have also initiated ambitious projects for harnessing the Renewables.

Present installed capacities of non-conventional renewable energy plants (except hydro) in India are negligible.

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U.S. Energy Consumption by Energy Source, 2003-2007 (Quadrillion Btu)Energy Source 2003 2004 2005 2006 2007Total 98.209 100.351 100.503 99.861 101.605Fossil Fuels 84.078 85.830 85.816 84.662 86.253  Coal 22.321 22.466 22.795 22.452 22.786  Coal Coke Net Imports

0.051 0.138 0.044 0.061 0.025

  Natural Gasa 22.897 22.931 22.583 22.191 23.625  Petroleumb 38.809 40.294 40.393 39.958 39.818Electricity Net Imports

0.022 0.039 0.084 0.063 0.106

Nuclear 7.959 8.222 8.160 8.214 8.415Renewable 6.150 6.261 6.444 6.922 6.830    Biomassc 2.817 3.023 3.154 3.374 3.615        Biofuels 0.414 0.513 0.595 0.795 1.018        Waste 0.401 0.389 0.403 0.407 0.431        Wood Derived Fuels

2.002 2.121 2.156 2.172 2.165

   Geothermal 0.331 0.341 0.343 0.343 0.353   Hydroelectric Conventional

2.825 2.690 2.703 2.869 2.463

   Solar/PV 0.064 0.065 0.066 0.072 0.080   Wind 0.115 0.142 0.178 0.264 0.319a Includes supplemental gaseous fuels.b Petroleum products supplied, including natural gas plant liquids and crude oil burned as fuel.c Biomass includes: biofuels, waste (landfill gas, MSW biogenic, and other biomass), wood and wood-derived fuels.MSW=Municipal Solid Waste.Note: Ethanol is included only in biofuels.  In earlier issues of this report, ethanol was included both in petroleum and biofuels, but counted only once in total energy consumption.  Totals may not equal sum of components due to independent rounding. Data for 2007 is preliminary.Sources: Non-renewable energy: Energy Information Administration (EIA), Monthly Energy Review (MER) March 2008,  DOE/EIA-0035 (2008/03) (Washington,DC, March 2008,)  

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Global Carbon Cycle (Billion Metric Tons Carbon)

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World Renewables Energy SourcesResource Form of delivered energy

(Application) comments

Solar: Total Solar radiation ab sorbed by the earth and its atmosphere is 3.8 x1024 J/yr.

Low temperature heat (space heating water heati ng and electricity)

Million of solar water heaters and solar cookers are in use.

Solar cells and power towers are in operation.

Wind: The kinetic energy available in the atmosphere circula tion is 7.5 x1020 J

Electricity Several multi-megawatt wind turbines are in operation and many more in construction.

Mechanical energy (Pump ing transport)

There are numbers of small wind turbines and wind pumps in use.

Biomass: Total solar radiation ab sorbed by plants is 1.3 x 1021 J/yr.

High temperature heat (cooking, smelting etc.)

Bio-mass (principally wood accounts for about 15% of the world's (commercial fuel) consump tion; it provides over 80% of the energy needs of many developing countries.

The worlds standing biomass has an energy con tent of about 1.5 x 1021 J.

Bio-gas (cooking, mechani cal power etc.)

There are millions of biogas plants in opera tion, most of them are in China.

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World Renewables Energy Sources Resource Form of delivered energy

(Application) comments

Alcohol(transport) Several thousand, million liters of alcohol are being produced notably in Brazil and the U.S. Production is increasing rapidly ; many countries have lunched liquid bio-fuel programmes.

Geothermal: The heat flux from the earth's interior through the surface is 9.5 x 1020J/yr.

Low temperature heat (bathing. space and water heating)

Geothermal energy supplies about 5350 MW of heat for use in bathing principally in Japan, but also in Hungary, Iceland and Italy. More than a lakh houses are supplied with heat from geothermal wells. The installed capacity is more than 2650 MW (thermal).

The total amount of heat stored in water or stream to a depth of 10 km is estimated to be 4 x 1021J ; that stored in the first 10 km of dry rock is around 1027 J.

Electricity Installed capacity is more than 2500 MW but output is expected to increase more than seven fold by 2000.

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World Renewables Energy Sources Resource Form of delivered

energy (Application) comments Tidal: Energy dissipated in con nection with slowing down rotation of the earth as a result of tidal action is around 1026 J/yr.

Electricity Only one large tidal barrage is in operation (at La Rance in France) and there are small schemes in Russia and China. Total installed capacity is about 240 MW and the output around 0.5 TWh/yr.

Wave: The amount of energy stored as kinetic energy in waves may be of the order of 1018 J.

Electricity The Japanese wave energy research vessel, the Kaimei, has an installed capacity of about 1 MW. There are, in addition several hundred wave powered navigational buoys: Designs after large prototype wave energy converters are being drawn up.

Hydro: The annual precipitation land amounts to about 1.1 x 1017 kg of water. Taking the average elevation of land area as 840 m, the annually accumulated potential ener gy would be

9 x 1020 J.

Electricity Large hydroscheme15 provide about one quarter of the world'l5 total electricity supply and more than 40% of the electricity used in developing countries. The installed capacity is more than 363 GW. The technically usable potential is estimated to be 2215 GW or 19000 TWb/yr. There are no accurate estimates of the number of capacity of small hydroplants currently in operation.

Primary Energy

Resources

Non-electric routes

Electrical route

Final Energy

consumption

Two alternate route of energy supply

World’s 48%

World’s 40%

12% by non-commercial route

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.

The yield ratio of the total sequence with n = 2 respectively n = 3 stations is calculated according to the product rule

.The factors have values which depend on the state of technological development in every county. At the beginning of the 21. century the values in fully developed countries were

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Primary Energy Processing Electrical power plant

Electrical energy

Consumer

Electrical energy route

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Efficiencies for various conversion engines

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The second image above shows some of the conversions used in powering vehicles

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Individual fuel consumption in 24 years and the years of complete exhaustion of individual fuels

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Global primary energy structure, shares (%) of oil and gas, coal, and non-fossil (zero-carbon) energy sources - historical development from 1850 to 1990 and in SRES scenarios. Each corner of the triangle corresponds to a hypothetical situation in which all primary energy is supplied by a single source - oil and gas on the top, coal to the left, and non-fossil sources (renewables and nuclear) to the right. Constant market shares of these energies are denoted by their respective isoshare lines. Historical data from 1850 to 1990 are based on Nakic´enovic´ et al. (1998). For 1990 to 2100, alternative trajectories show the changes in the energy systems structures across SRES scenarios. They are grouped by shaded areas for the scenario families A1B, A2, B1, and B2 with respective markers shown as lines. In addition, the four scenario groups within the A1 family A1B, A1C, A1G, and A1T, which explore different technological developments in the energy systems, are shaded individually. In the SPM, A1C and A1G are combined into one fossil-intensive group A1FI. For comparison the IS92 scenario series are also shown, clustering along two trajectories (IS92c,d and IS92a,b,e,f). For model results that do not include non-commercial energies, the corresponding estimates from the emulations of the various marker scenarios by the MESSAGE model were added to the original model outputs.

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Global renewable energy potentials for 2020 to 2025, maximum technical potentials, and annual flows, in EJ. Data

sources: Watson et al., 1996; Enquete-Kommission, 1990.

  Consumption Potentials by Long-term Technical Potentials

Annual Flows  1860-1990 1990 2020-2025

Hydro 560 21 35-55 >130 >400Geothermal - <a 4 >20 >800

Wind - - 7-10 >130 >200,000

Ocean - - 2 >20 >300

Solar - - 16-22 >2,600 >3,000,000

Biomass 1,150 55 72-137 >1,300 >3,000

Total 1,710 76 130-230 >4,200 >3,000,000

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Non-electrical energy route

Primary energy Processing Secondary energy

Transport by road/rail/ocean/pipeline

Consumer

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Renewable Energy sources like wind, solar heat, waves etc. cannot be stored in original natural form. It is converted continuously to electrical form. transmitted, distributed and utilized without long-term intermediate storage. The Renewables are available free of cost. Hence, consumption of renewable should be maximized. Non-renewable should be conserved for some more decades / centuries.

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Thank you for your kind attention

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Solar Energy Storage

Introduction • Solar energy is a time dependent and

intermittent energy resource• The need for energy storage of some kind

is almost immediate evident for a solar electric system.

• solar energy is most available will rarely coincide exactly with the demand for electrical energy

• high insolation times could be used to provide a continuous electrical output or thermal output

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• Permit solar energy to be captured when insolation is highest

• it possible to deliver electrical load power demand during times

• Be located close to the load• Improve the reliability of the solar thermal

as well as solar electric system• Permit a better match between the solar

energy input and the load demand output

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Storage of solar energy in a solar system may:

Optimum capacity of an energy storage system • The expected time dependence of solar radiation

availability. • The nature of load to be expected on the process. • The degree of reliability needed for the process. • The manner in which auxiliary energy is supplied. • The size of the solar thermal power system or solar-electric

generator. • The cost per kWh of the stored energy. • The permissible capital cost allocated to storage. • Environmental and safety considerations. • An economic analysis that determines how much of the

total usually annual loads should be carried by solar and how much by auxiliary energy sources.

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Solar Energy Storage Systems

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Thermal StorageEnergy can be stored

by heating, melting or vaporization of material, and the energy becomes available as heat.

I. Sensible heat storage

II. Latent heat

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I. (A ) water storageThe most common heat transfer fluid for a solar system

is water, and the easiest way to store thermal energy is by storing the water directly in a well insulated tank.

Characteristics for storage medium• It is an inexpensive, readily available and useful

material to store sensible heat. • It has high thermal storage capacity. • Energy addition and removal from this type of

storage is done by medium itself. thus eliminating any temperature drop between transport fluid and storage medium.

• Pumping cost is small

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I. (B) Packed Bed Exchanger Storage

Sensible heat storage with air as the energy transport mechanism, rock, gravel, or crushed stone in a bin has the advantage of providing a large, cheap heat transfer surface.

Rock does have the following advantages over water• Rock is more easily contained than water.• Rock acts as its own heat exchanger, which reduces total

system cost. • It can be easily used for thermal storage at high

temperatures, much higher than 100°C; storage at high temperature where water can not be used in liquid form without an experience, pressurized storage tank.

• The heat transfer coefficient between the air and solid is high. • The cost of storage material is low. • The conductivity of the bed is low when air flow is not

present.

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II. (B) Latent heat storageMaterials that undergo a change of phase in a suitable temperature range may be useful for

energy storage • The phase change must be accompanied by high latent heat • The phase change must be reversible over a very large number of cycles without

degradation. • The phase change must occur with limited super cooling. • Means must be available to contain the material and transfer heat into it and out of it. • The cost of materials and its containers must be reasonable. • Its phase change must occur close to its actual melting temperature. • The phase change must have a high latent heat effect, that is, it must store large

quantities of heat. • The material must be available in large quantities. • The preparation of the phase changing material for use must be relatively simple. • The material must be harmless (non-toxic, non-inflammable, non-combustible, non-

corrosive). • A small volume change during the phase change. • The material should have high thermal conductivity in both the phases.

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Materials for phase change energy storage.

• Glauber's salt (Na2S04.10 H20), water, Fe(N03)2 .6 H20, and salt Eutectics

• Organic­compound­or substances­serve as heat storage materials Paraffin­and fatty­acids

• Refractory materials (MgO, Al203, SiO2) are also suitable for high temperature sensible heat storage in addition to Rock or pebble bed storage. Some thermal storage materials such as ZnCI2, Na(OH)3, NaOH, KOH-ZnCl2 KCl-MgCl2-NaCI, MgCl2 NaCl, etc. are also used for the temperature range of 200-450°C.

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Latent Heat Storage Arrangement

Electrical StorageCapacitor storageInductor storageBattery storage: stored electrochemically,­

and later regained as electrical energy. Battery­storage­system­may­be­included­under­chemical­energy­storage­also.­

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Chemical Storage1. Storage­in­the­form­of­fuel:

• storage battery in which the reactant is generated by a photochemical reaction brought about by solar radiation. The battery is charged photo -chemically and discharged electrically whenever needed.

• It is also possible to electrolyze water with solar generated electrical energy, store O2 and H2 and recombine in a fuel cell to regain electrical energy

• Solar energy could be used by the anaerobic fermentation• Photosynthesis has been mentioned as a method of solar energy

conversion• The carbohydrates are stable at room temperature; but at high

temperature the reaction is reversed, releasing the stored energy in thermal form.

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2. Thermo-chemical­energy­storage­(Reversible­chemical­reactions).

Thermo-chemical storage systems are suitable for medium or high temperature applications only. For storage of high temperature heat, some reversible chemical reactions appear to be very attractive.

Advantages of thermo-chemical storage include high energy density storage at ambient temperatures for long periods without thermal losses and potential for heat pumping and energy transport over long distances.

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3. Hydrogen­storage.

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Mechanical Energy Storage(i) Pumped hydroelectric

storage:

the water is allowed to flow back down through a hydraulic­turbine­which drives an electric generator. The overall efficiency of the pumped­storage,­that is, the percentage or the electrical energy used to pump the water is recovered as electrical energy is about 70%.

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(ii) Compressed Air Storage. when the wind is not blowing the energy stored in the air could be utilized to drive an air turbine, whose shaft would then drive a generator

(iii) Flywheel storage.

The energy is stored as kinetic energy, most of which can be electrically regained when the flywheel is run as a generator

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Electromagnetic energy storage Electromagnetic energy storage requires the

use of super conducting materials. These materials (metals and alloys) suddenly lose essentially all resistance to the flow of electricity when cooled below a certain very low temperature. If maintained below this temperature a super conducting metal (or alloy) can carry strong electric currents with little or no loss.

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Introduction: A natural or artificial body of water for collecting and absorbing solar radiation energy and storing it as heat. Thus a solar pond combines solar energy collection and sensible heat storage.

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Solar Pond

FeaturesThe simplest type of solar pond is very shallow, about 5 - 10

cm deep, with a radiation absorbing (e.g., black plastic) bottom.

All the pond water can become hot enough for use in space heating and agricultural and other processes.

the water soon acquires a fairly uniform temperature. Solar ponds promise an economical way over flat-plate

collectors and energy storage by employing a mass of water for both collection and storage of solar energy.

The energy is stored in low grade (60 to 100ºC) Salt-gradient solar pond or non convecting solar pond' are

also often used, as to distinguish these ponds from 'shallow solar pond'.

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The salt used in a solar pond for creating density gradient should have the following characteristics:

It must have a high value of solubility to allow high solution

densities. The solubility should not vary appreciably with temperature. Its solution must be adequately transparent to solar radiation. It must be environmentally benign, safe to handle the ground

water. It must be available in abundance near site so that its total

delivered cost is low, and It must be inexpensive.

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Extraction of Thermal EnergyThe process of heat extraction, accomplished

by hot brine with drawn and cool brine return in a laminar flow.

Thermal energy from solar pond is used to drive a Rankine cycle heat engine. Hot water from the bottom level of the pond is pumped to the evaporator.

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Applications of Solar Ponds1. Heating and

Cooling of Buildings. Because of the large heat storage capability in the lower convective zone of the solar pond, it has ideal use for heating even at high latitude stations and for several cloudy days.

2. Production of Power.

A solar pond can be used to generate electricity by driving a thermo-electric device or an organic Rankine cycle engine-a turbine powered by evaporating an organic fluid with a low boiling point.

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3. Industrial Process Heat.

Industrial process heat is the thermal energy used directly in the preparation and of treatment of materials and goods manufactured by industry.

4. Desalination.

The low cost thermal energy can used to desalt or otherwise purify water for drinking or irrigation.

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5. Heating animal housing and drying crops on farms.

6. Heat for biomass conversion. Site built solar ponds could provide heat to convert biomass to alcohol or methane

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Thank you for kind attention

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Solar Energy Storage

Solar Energy Storage

Introduction • Solar energy is a time dependent and

intermittent energy resource• The need for energy storage of some kind

is almost immediate evident for a solar electric system.

• solar energy is most available will rarely coincide exactly with the demand for electrical energy

• high insolation times could be used to provide a continuous electrical output or thermal output

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• Permit solar energy to be captured when insolation is highest

• it possible to deliver electrical load power demand during times

• Be located close to the load• Improve the reliability of the solar thermal

as well as solar electric system• Permit a better match between the solar

energy input and the load demand output

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Storage of solar energy in a solar system may:

Optimum capacity of an energy storage system • The expected time dependence of solar radiation

availability. • The nature of load to be expected on the process. • The degree of reliability needed for the process. • The manner in which auxiliary energy is supplied. • The size of the solar thermal power system or solar-electric

generator. • The cost per kWh of the stored energy. • The permissible capital cost allocated to storage. • Environmental and safety considerations. • An economic analysis that determines how much of the

total usually annual loads should be carried by solar and how much by auxiliary energy sources.

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Solar Energy Storage Systems

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Thermal StorageEnergy can be stored

by heating, melting or vaporization of material, and the energy becomes available as heat.

I. Sensible heat storage

II. Latent heat

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I. (A ) water storageThe most common heat transfer fluid for a solar system

is water, and the easiest way to store thermal energy is by storing the water directly in a well insulated tank.

Characteristics for storage medium• It is an inexpensive, readily available and useful

material to store sensible heat. • It has high thermal storage capacity. • Energy addition and removal from this type of

storage is done by medium itself. thus eliminating any temperature drop between transport fluid and storage medium.

• Pumping cost is small

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I. (B) Packed Bed Exchanger Storage

Sensible heat storage with air as the energy transport mechanism, rock, gravel, or crushed stone in a bin has the advantage of providing a large, cheap heat transfer surface.

Rock does have the following advantages over water• Rock is more easily contained than water.• Rock acts as its own heat exchanger, which reduces total

system cost. • It can be easily used for thermal storage at high

temperatures, much higher than 100°C; storage at high temperature where water can not be used in liquid form without an experience, pressurized storage tank.

• The heat transfer coefficient between the air and solid is high. • The cost of storage material is low. • The conductivity of the bed is low when air flow is not

present.

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II. (B) Latent heat storage

Materials that undergo a change of phase in a suitable temperature range may be useful for energy storage

• The phase change must be accompanied by high latent heat • The phase change must be reversible over a very large number of cycles without degradation. • The phase change must occur with limited super cooling. • Means must be available to contain the material and transfer heat into it and out of it. • The cost of materials and its containers must be reasonable. • Its phase change must occur close to its actual melting temperature. • The phase change must have a high latent heat effect, that is, it must store large quantities of

heat. • The material must be available in large quantities. • The preparation of the phase changing material for use must be relatively simple. • The material must be harmless (non-toxic, non-inflammable, non-combustible, non-corrosive). • A small volume change during the phase change. • The material should have high thermal conductivity in both the phases.

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Materials for phase change energy storage.

• Glauber's salt (Na2S04.10 H20), water, Fe(N03)2 .6 H20, and salt Eutectics

• Organic­compound­or substances­serve as heat storage materials Paraffin­and fatty­acids

• Refractory materials (MgO, Al203, SiO2) are also suitable for high temperature sensible heat storage in addition to Rock or pebble bed storage. Some thermal storage materials such as ZnCI2, Na(OH)3, NaOH, KOH-ZnCl2 KCl-MgCl2-NaCI, MgCl2 NaCl, etc. are also used for the temperature range of 200-450°C.

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Latent Heat Storage Arrangement

Electrical StorageCapacitor storageInductor storageBattery storage: stored electrochemically,­

and later regained as electrical energy. Battery­storage­system­may­be­included­under­chemical­energy­storage­also.­

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Chemical Storage1. Storage­in­the­form­of­fuel:

• storage battery in which the reactant is generated by a photochemical reaction brought about by solar radiation. The battery is charged photo -chemically and discharged electrically whenever needed.

• It is also possible to electrolyze water with solar generated electrical energy, store O2 and H2 and recombine in a fuel cell to regain electrical energy

• Solar energy could be used by the anaerobic fermentation• Photosynthesis has been mentioned as a method of solar energy

conversion• The carbohydrates are stable at room temperature; but at high

temperature the reaction is reversed, releasing the stored energy in thermal form.

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2. Thermo-chemical­energy­storage­(Reversible­chemical­reactions).

Thermo-chemical storage systems are suitable for medium or high temperature applications only. For storage of high temperature heat, some reversible chemical reactions appear to be very attractive.

Advantages of thermo-chemical storage include high energy density storage at ambient temperatures for long periods without thermal losses and potential for heat pumping and energy transport over long distances.

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3. Hydrogen­storage.

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Mechanical Energy Storage(i) Pumped hydroelectric

storage:

the water is allowed to flow back down through a hydraulic­turbine­which drives an electric generator. The overall efficiency of the pumped­storage,­that is, the percentage or the electrical energy used to pump the water is recovered as electrical energy is about 70%.

04/13/2023Solar Energy Storage145

(ii) Compressed Air Storage. when the wind is not blowing the energy stored in the air could be utilized to drive an air turbine, whose shaft would then drive a generator

(iii) Flywheel storage.

The energy is stored as kinetic energy, most of which can be electrically regained when the flywheel is run as a generator

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Electromagnetic energy storage Electromagnetic energy storage requires the

use of super conducting materials. These materials (metals and alloys) suddenly lose essentially all resistance to the flow of electricity when cooled below a certain very low temperature. If maintained below this temperature a super conducting metal (or alloy) can carry strong electric currents with little or no loss.

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Introduction: A natural or artificial body of water for collecting and absorbing solar radiation energy and storing it as heat. Thus a solar pond combines solar energy collection and sensible heat storage.

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Solar Pond

FeaturesThe simplest type of solar pond is very shallow, about 5 - 10

cm deep, with a radiation absorbing (e.g., black plastic) bottom.

All the pond water can become hot enough for use in space heating and agricultural and other processes.

the water soon acquires a fairly uniform temperature. Solar ponds promise an economical way over flat-plate

collectors and energy storage by employing a mass of water for both collection and storage of solar energy.

The energy is stored in low grade (60 to 100ºC) Salt-gradient solar pond or non convecting solar pond' are

also often used, as to distinguish these ponds from 'shallow solar pond'.

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The salt used in a solar pond for creating density gradient should have the following characteristics:

It must have a high value of solubility to allow high solution

densities. The solubility should not vary appreciably with temperature. Its solution must be adequately transparent to solar radiation. It must be environmentally benign, safe to handle the ground

water. It must be available in abundance near site so that its total

delivered cost is low, and It must be inexpensive.

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Extraction of Thermal EnergyThe process of heat extraction, accomplished

by hot brine with drawn and cool brine return in a laminar flow.

Thermal energy from solar pond is used to drive a Rankine cycle heat engine. Hot water from the bottom level of the pond is pumped to the evaporator.

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Applications of Solar Ponds1. Heating and

Cooling of Buildings. Because of the large heat storage capability in the lower convective zone of the solar pond, it has ideal use for heating even at high latitude stations and for several cloudy days.

2. Production of Power.

A solar pond can be used to generate electricity by driving a thermo-electric device or an organic Rankine cycle engine-a turbine powered by evaporating an organic fluid with a low boiling point.

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3. Industrial Process Heat.

Industrial process heat is the thermal energy used directly in the preparation and of treatment of materials and goods manufactured by industry.

4. Desalination.

The low cost thermal energy can used to desalt or otherwise purify water for drinking or irrigation.

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5. Heating animal housing and drying crops on farms.

6. Heat for biomass conversion. Site built solar ponds could provide heat to convert biomass to alcohol or methane

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Thank you for kind attention

APPLICATIONOF

SOLAR ENERGY

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Introduction Three general categories: (a) Direct­ Thermal­ Application­make direct use of heat, resulting from the

absorption of solar radiation, for space heating (and cooling) of residences and other building, so provide hot water service for such buildings, and to supply heat for agricultural industrial, and other processes that require only moderate temperatures.

(b) Solar­ Electric­ Applications­are those in which solar energy is converted directly or indirectly into electrical energy. General conversion methods being investigated are :

I. Solar thermal methods involve production of high temperatures, such as are required to boil water or other working fluid for operating turbines which drive electric generators. These are considered under solar­thermal­electric­conversion.­

II. Photovoltaic­Methods­make use of devices (Solar Cells) to convert solar energy directly into electrical energy without machinery.

III. Wind­ Energy­ is the form of solar energy that can be converted into mechanical (rotational) energy and hence into electrical energy by means of a generator. This is indirect­use of solar energy to generate electricity.

IV. Ocean­ thermal­ energy­ conversion­ depends on the difference in temperature between solar heated surface water and cold deep ocean water to operate a vapor expansion turbine and electric generator. This is indirect use of solar energy.

(C) Energy from Biomass and Bio-gas, refers to the conversion into clean fuels or other energy related product of organic matter derived directly or indirectly from plants which use solar energy to grow.

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Direct solar energy applications are:(1) Solar water heating.(2) Space heating. (3) Space cooling. (4) Solar energy: Thermal electric conversion. (5) Solar energy: Photovoltaic electric conversion. (6) Solar distillation. (7) Solar pumping. (8) Agriculture and industrial process heat. (9) Solar furnace. (10) Solar cooking. (11) Solar production of hydrogen, and (12) Solar green houses.

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The basic elements of a solar water heater are:

I. Flat plate collector.

II. Storage tank.

III. Circulation system and auxiliary heating system.

IV. Control of the system. 04/13/2023Application of Solar Energy16

5

(1) Solar water heating.

Some typical and commercial designs of solar water heaters are:

(I) Natural circulation solar water heater (pressurized).

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(ii) Natural circulation solar water heater (non-pressurized).

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(iii) Forced circulation solar water heater

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(2) Space-Heating (or Solar heating of Building)

passive­systems:­in which solar radiation is collected by some element of the structure itself, or admitted directly into building through large, south facing windows.

Active­systems:­­which generally consists of (a)­separate solar collectors, which may

heat either water or air, (b)­storage devices which can

accumulate the collected energy for use at nights and during inclement days, and,

(c)­a back up system to provide heat for protected periods of bad weather.

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Solar Heating Systems (A) Passive Heating Systems.

If a building is designed properly:

(i) It will function as a solar collector, collecting heat when the sun is shining and storing it for later use.

(ii) The building will function as a solar store house. It must store the heat for cool times when the sun is not shining, and store the cool for warm or hot periods when the sun is shining. Buildings which are made of heavy materials such as stone or concrete do this most effectively.

(iii) Building will function as a good heat trap. It must make good use of the heat (or cool) and let it escape only very slowly. This is done primarily by reducing the heat loss of the building through the use of insulation, reduction of infiltration and storm windows.

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The basic design principles of passive solar space-heating systems, that is, without mechanical components, fall into the following five general categories:

I. Direct gainII. Thermal storage wall: Dr. Felix FranceIII. Attached sun space IV. Roof storage V. Convective loop.

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Attached sun space

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Roof Storage

Convective Loop04/13/2023Application of Solar Energy17

7

Active Space-Heating Systems (I)Basic hot water system

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Advantages I. In case of water heating, a

common heat transfer and storage medium, water is used, this avoids temperature drop during transfer of energy into and out of the storage.

II. It requires relatively smaller storage volume.

III. It can be easily adopted to supply of energy to absorption air conditioners, and Relatively low energy requirements for pumping of the heat transfer fluid.

Disadvantages I. Solar water heating system will

probably operate at lower water temperature than conventional water systems and thus require additional heat transfer area or equivalent means to transfer heat into building.

II. Water heaters may also operate at excessively high temperatures (particularly in spring and fall) and means must be provided to remove energy and avoid boiling and pressure build up.

III. Collector storage has to be designed for overheating during the period of no energy level.

IV. Care has to be taken to avoid corrosion problems.

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Basic Hot air System

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Advantages

I. There is no problem with freezing in the collectors.

II. Corrosion problems are minimized.

III. Conventional control equipment for air heating is already available and can be readily used.

IV. Problems of designing for over heating during periods of no energy removal are minimized, and,

V. The working fluid is air and the warm air heating systems are ill common use.

Disadvantages

I. Relatively higher power costs for pumping air through the storage medium.

II. Relatively large volumes of storage units.

III. Difficulty of adding absorption air conditioners to the system.

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I. Low temperature cycles using flat plate collector or solar cycle.

II. Concentrating collectors for medium and high temperature cycle.

III. Power tower concept or central receiver system.

IV. Distributed collector system.

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(4) Solar energy: Thermal electric conversion.

Low temperature system

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Medium Temperature Systems with Concentrating Collectors.

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High Temperature Systems

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Solar distillation.

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H

hw

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Solar pumpingThe basic system consists of the following

components :1. The solar collectors, may be

(a) Flat plate collectors or solar pond (b) Stationary concentrator (CPC) (c) Sun-tracking concentrators, (cylindrical

parabolic trough concentrator or heliostats).

2. The heat transport system. 3. Boiler or Heat Exchanger.

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4. Heat engine, it may be (a) Rankine engine (b) Stirling hot gas engine(c) Brayton cycle gas turbine(d) Rotary piston engine.5. Condenser. 6. Pump, it may be­

(a)­Reciprocating pump (b)­Centrifugal pump (c)­Diaphragm pump (d) Rotary pump.

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Reciprocating engine

Vapor turbine

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The collector area to a large extend is determined by the overall efficiency of the system

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Agriculture and industrial process heat

Solar energy for thermal applications in industries has proved to be economically viable at present for temperatures less than 100°C. With intensive development in the area of fixed and tracking con centrators, temperatures 0 to 300°C will be feasible. The technology is expected to be matured in near future. In the present energy context, it is desirable to provide thermal energy below 300°C from solar

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These applications of solar energy may be considered in three general categories, according to the temperature range within which the heat is supplied.

1. Low temperatures below 100°C: based on the use or flat-plate collectors, with either air or water as the heat transport medium.

Among the potential applications of low temperature heat in the agriculture­are the following:

Heating and cooling of commercial green houses. Space heating of livestock shelters, dairy facilities and

poultry houses. Curing of bricks, plaster board etc. Drying grain, soybeans,

peanut pods, fruits, tobacco, onions and kiln (Lumber) Solar energy can also be used to convert salty water (or other impure water) into potable. water by distillation.

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2. Intermediate temperatures 100 to 175°C:LaundriesFabric drying Textile dyeing Food processing and can washingKraft pulping (in paper industries) Laminating and drying glass fiberDrying and baking in automobile industriesPickling (in steel industries) etc.

3. High temperatures above 175°C:Steam at temperatures above 175°C is used extensively in

Industry particularly in the generation of electric power.

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The several advantages of industrial applications over residential or commercial ones are :

Industrial loads are mostly on continuous basis throughout the year.

Industrial plants have maintenance crew, or in small plants ,killed people, who can attend to smooth operation of solar systems.

Total quantum of energy replaced by solar is significantly more causing higher reduction in oil imports and diversion of coal for high temperature tasks.

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limitations Intermittent availability of solar energy.

Instantaneous area. In all the cases roof area may not be adequate to accommodate required collector area. Additional costly land may have to be used. In some cases, roof have east west slopping, instead of north glazing type, rending placement of collectors to be costly and unaesthetic.

Industrial effluents can be harmful to the transparent covers and reflecting surfaces.

Through pay back period has come down to 3-5 years (hot water and air only), high initial capital investment is a major impediments.

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Solar Furnace A solar furnace is an instrument to get high temperatures by

concentrating solar radiations onto a specimen. Solar furnaces have long been used for scientific investigations.

Applications: Used for high temperature application in chemical reactions

French scientist Lavoisier used 1774with a lens as tall as man

German scientist Strauble devised1921a solar furnace composed of a paraboloidal concentrator and a lens.

Specific points: The first large solar furnace with a thermal power of 45 kW was

completed in France in 1952. A­similar furnace with a power of about 35 kW, was constructed for

the U.S. Army at Natick, Massachusetts, in 1958. The world's largest solar furnace, with a design thermal pee of

1000 kW, commenced operation at Odeillo in the French Pyrenees in 1973 consisting 63 heliostats having an area 45 sq. m.

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Principle of Working

Uses of solar furnace The solar furnace is an excellent means for studying

properties of ceramics at high temperatures above the range ordinarily measured in the laboratory with flames and electric currents.

Physical measurements include melting points, phase changes, specific heat, thermal expansion, thermal conductance, magnetic susceptibility and thermionic emission.

Several useful metallurgical and chemical operations have been carried out at high temperatures in the solar furnaces.

The melting and sintering of temperature ceramics such as zirconia is easily accomplished.

Direct high temperature production or zirconia from zircon and alkali, beryllia from beryl, and tungsten from wolframite is carried out in solar furnaces.

Purification of a refractory (Al203) by sublimation at high temperatures also has been carried out

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Advantages In a solar furnace heating is carried out without any

contamination and temperature is easily controlled by changing the position of the material in focus.

It gives an extremely high temperature. It provides very rapid heating and cooling. Various property measurements are possible on an open

specimen. Contamination by ions does not occur in fusion which might

happen in the case of plasma or oxy hydrogen flame. Proper desirable atmosphere can be provided to the specimen

Limitations Its use is limited to sunny days, and to 4-5 hours only (maximum

bright sun shine hours), and high cost.

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Advantages and Limitations of a Solar Furnace

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Solar Cooking The first solar cooker was developed in the

year 1945 by Mr. M.K Ghosh of Jamshedpur a freedom fighter.

Later in 1953 NPL of India developed a parabolic solar cooker

Basically there are three designs of solar cooker:

Flat plate box type solar cooker with or without reflector

Multi reflector type solar oven and Parabolic disc concentrator type solar cooker.

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Flat plate box type design is the simplest of all the designs. Maximum no load temperature with a single reflector reaches up to l50°C.

In multi reflector oven four square or triangular or rectangular reflectors are mounted on the oven body. They all reflect the solar radiations into the cooking zone in which cooking utensils are placed. Temperature obtained is of the order of 200°C. The maximum temperature can reach to 250°C

Parabolic disc concentrator type solar cooker, temperatures of the order of 450°C can be obtained in which solar radiations are concentrated onto a focal point

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Merits of a solar cooker: No attention is needed

during cooking as in other devices.

No fuel is required. Negligible

maintenance cost. No pollution. Vitamins of the food

are not destroyed and food cooked is nutritive and delicious with natural taste.

. No problem of charring

of food and no over flowing.

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Limitations of a solar cooker

One has to cook according to the sun shine, the menu has to be preplanned.

One can not cook at short notice and food can not be cooked in the night or during cloudy days.

It takes comparatively more time.

Chapaties­are not cooked because high temperature for baking is required and also needs manupulation at the time of baking. Box Type Solar Over (Multi reflector Type)

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Solar Green Houses Definition: 1. A green house is a growth chamber which offers the possibilities

of year round plant production. These are effective solar collectors. These can also be geared to the needs of the rural, urban and suburban populations. A green house attached to a residence creates a pleasant improvement in the physical and mental environment of its occupants; designed in a truly passive solar collection manner with a well-applied heat store, this type of solar collector (or power house) may also provide much of the required winter heat. Solar green houses are relatively easy to build with simple technology and low cost materials.

2. Green houses provide crop cultivation under controlled environment. A green house is a structure covered with transparent material that utilizes solar radiant energy to grow plants and may have beating, cooling and ventilating equipments for temperature control.

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Soil temperature Air temperature Air humidity Soil moisture Light Air composition Root medium composition Protection from plant enemies Exposure to rain Hail storm etc.

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The plant environment refers :

Advantages of Green housesA source of inexpensive, good quality food

that one grows one A source of additional heat (temperature

control) for the house attached to it, A source of moderator for the humidity

(humidity control) in the house.

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Attached­ green­ house:­which may be joined onto almost any suitable building structure.

Porch­ type green houses: which may be designed as the entrance to a house, factory or office.

Free­ standing­ green houses: which may be situated on any convenient patch or piece of waste ground.

Pit­ type green houses: which are usually employed on differing level or sloping land scapes, and for the purpose of heat retention.

Cold­ frame­ type of green houses: which are simply hot-bed, or plant facing frames equipped with a sloping roof.

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Types of Green Houses

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Solar Production of Hydrogen Methods of producing hydrogen from solar

energy There are four basic methods: 1. Direct thermal, 2. Thermo chemical, 3. Electrolytic, and 4. Photolytic.

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Direct thermal

Water is heated up to 3000o C

X1, X2 and X3 are mole fractions

Water should be decomposed at fairly high temperature (for equilibrium decomposition) combined with a reduced pressure. The energy for dissociation of hydrogen can be obtained from the solar energy. An optical system which collects solar radiation and con centrates

Advantages of this methods are :

1. High thermal efficiency,

2. Negligible environmental impact, and

3. Intermediary chemicals are not required.

4. Because of high temperature requirements, it requires extensive research for commercial application.

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2322212 O xH x OHxheat OH

Thermo chemical

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ElectrolyteThe cell consists of electrodes dipped in an electrolyte and connected

to a d.c. supply. Water with some conducting chemicals is used as an electrolyte. When sufficient poten tial is applied between the electrodes to cause a current to flow, oxygen is liberated at the anode and hydrogen at the cathode.

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In this method, the solar energy is first converted to d.c. electric power, then hydrogen through electrolysis. Hence it is especially suited for coupling with ocean, thermal, wind, hydro and photovoltaic forms of solar energy since in these cases solar energy is converted to electricity.

Photolytic

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Photons in the ultraviolet region of radiation spectrum passes the energies needed for the direct photolysis of water, in the presence of catalyst.

Note that photo catalyst X is not consumed, but is regenerated and available for reuse. Biological photo catalysts are also in existence.

Among the four basic methods for producing hydrogen from solar energy. the direct thermal method has the potential of highest thermal efficiency. followed by thermo chemical. electrolyte and photolytic method.

Schematic representation of the two-step water-splitting cycle using theZn/ZnO redox system for the solar production of hydrogen

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Solar Hydrogen from Landfill Gas

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Reaction 2CO + H2O H2 + CO2 ∆Hf = 40.6 kJ/mole

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Components for coupling solar-driven, photosynthetic water oxidation to hydrogen (H2) production in photobiological systems are shown on the left. Solar-driven water splitting by the photosynthetic apparatus generates charge that is transferred to a mobile charge carrier, ferredoxin, and ultimately to hydrogenase for catalytic H2 production. On the right, components of an artificial, solar biohybrid H2 production device. If used as a cathode in a solar capture device (black arrows), charge generation and transfer from the solar device to the cathode drives catalytic H2 production. If the biohybrid is composed of semiconducting materials of appropriate energetics, the material itself generates the charge for catalytic H2 production (red arrows). e–: Photogenerated charge. D, D+: Reduced, oxidized state, respectively, of a sacrificial dono molecule.

Biohybrid catalysts for solar hydrogen production

Diagram shows that photovoltaic material behind the film converts the rest of the solar spectrum into electricity, supplying the device with extra voltage to boost hydrogen production.

BUBBLING WITH HYDROGEN. In this tandem cell, a nanostructured metal-oxide film absorbs the sun's ultraviolet and blue light to split water.

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CO2 Capture from Air and Co-production of Hydrogen

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Pounds Carbon Dioxide Emissions Per Pound of Hydrogen Produced

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Thank you

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Introduction - Applications - Utilization of Geothermal Energy Geothermal Energy Resources - Characteristics of Geothermal Resources - Geothermal Gradients - Non-uniform Geothermal Gradients Hydro Geothermal Resources - Geopressure Geothermal Resources Geopressure Energy Reserves - Hot Dry Rock Geothermal Resources Merits and Demerits of Petro-Geothermal Energy Plants - Fracture Cavity by High Pressure Water – Fracture Cavity by Chemical Explosives - Geothermal Fluids for Electrical Power Plants - Geothermal Electrical Power Plants.

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Geothermal Energy

Geothermal Energy

Introduction The thermal energy contained in the interior of

the earth is called the geothermal energy

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IMPORTANT ASPECTS ABOUT THE GEOTHERMAL ENERGY

Characteristics RemarksForm of energy Thermal energy in the form of hot water, steam, geothermal

brine, mixture of these fluids

Availability Generally available deep inside the earth at a depth more than about 80 km. Hence, generally not Possible to extract

In a few locations in the world, deposits are at depths of 300 m to 3000 m. Such locations are called the geothermal Fields.

Method of extraction Deep product.ion wells are drilled in the geothermal fields. The hot steam/water/brine is extracted from the geothermal deposits by the production wells, by

pumping or natural pressure.

Geothermal fluids Hot water.

Hot brine

Wet steam, Mixture of above.

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Characteristics Remarks

Countries which have - Chile - New Zealand - EI Salvadir

known Geothermal - Philippines -Hungary - Indonesia

Resources. - Iceland -Turkey - Italy

- U.S.A. -Japan - U.S.5.R.

- Mexico

Application of - Hot water for baths, therapy

Geothermal Energy - District heating, space heating

- Hot water irrigation in cold countries

- Air conditioning

- Green house healing

- Process heat

- Minerals in geothermal fluid

- electrical power generation.

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Engineering criteriafor applications of Geothermal hot water.

Application Temperature (more than)

·C

Depth (less than)

km

Discharge(more Than)

m3/day

Electrical power generation by steam water cycle

100·C 3km 10000

Electrical power generation by binary cycle

70°C 2.5 km 25000

District healing 70·C 2.5 km 1000

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Range of Geothermal Power plant installed capacity - 5MW - 400MW

Average geothermal gradient - 30°C / 1000 m depth

Geothermal energy Released through earth's crust

- 0.06W/m2 About 1/1000th of solar energy on earth's surface

Total geothermal reserves in the earth - 4 x 1012 EJ

Renewable energy deposits available for use in upper 3 km zone - 4000 EJ

Rate at which the renewable can be tapped for production of electricity - 2 to 10 EJ/Yr.

Types of Geothermal energy deposits

- hydrothermal Hot water and steam, hot brine

- petrothermal Hot dry rock (HDR)

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Until 1904, the use of naturally available geothermal energy had been limited for the use of warm water baths, therapeutic treatments etc. After 1904 the geothermal energy is being used for many electrical power generation and non-electrical applications. The non-electrical applications include

Space heating Air-conditioning Greenhouse heating Process heat Medical therapy Mineral extractiondesalination plants heating houses, agricultural water, aquaculture water

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Applications of Geothermal Energy for Various Purposes

CountriesUtilization

Electrical Power Production

Non-electrical Applications

Chile

El Salvadore

Hungary

Iceland

Italy

Japan

Mexico

New Zealand

Philippines

Turkey

USA

USSR

France

Important criteria for engineering applications of geothermal water are

Temperature of geothermal fluid, °C Discharge rate, m3/day Useful life of production well, years. Depth of Aquifer (m) Mineral Contents gram/m3

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Engg. Criteria for resources for geothermal power

Type of powerAvg. Temp. of geothermal fluid, oC

Discharge of production well m3/day

Depth of drill hole (m)

Mineral content g/kg

Electrical power plant with steam-water cycle

185 to 255 10,000 650 to 3000 3 to 20

Electrical power generation with binary fluid cycle (Ammonia/water or Hydrocarbon/water, Freon/water)

70 to 150 25,000 500 to 2500 6 to40

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Geothermal Energy Resources

Depth increases

Temperature increases

30°C per 1000 m (Geothermal Gradient)

300°C geothermal fluid is available at 10 km depth

A few favorable geothermal deposits at relatively less depths (300 m to 3000 m)There are two types of geothermal­energy­deposits1. Hydro-geothermal energy resources

hot water and steam at relatively lesser depths (3000 m). Hot water, hot brine and steam can be extracted from such deposits

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2. Petro-geothermal energy deposits (HDR) The hot dry rocks at temperature around 200°C and depth about 2000 m form important deposits of geothermal energy.Two types of wells­are drilled in HDR sites. These are

called production wells and injection wells.

Water is pumped in through the injection well into the Hot Dry Rock fracture. The injected water collects heat from the hot dry rock and forms a deposit of hot water and steam in the fracture­within the rock.

Production­well­extracts the hot water and steam from the geothermal deposits in the hot dry rock. Petro Geothermal Energy Deposits may deliver mixture of hot water and steam of temperatures up to about 200°C for several decades

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Cross section of the earth with geothermal energy deposits, various types of rocks, volcanoes. furmoroles, hot springs etc.

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When hot water and steam reach the surface, they can form fumaroles, hot springs, mud pots and other interesting phenomena.

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When the rising hot water and steam is trapped in permeable and porous rocks under a layer of impermeable rock, it can form a geothermal reservoir.

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Origin of Geothermal Resources The earth was originally a mass of hot liquids, gases and

steam. As the fluids cooled by loosing heat to the ,atmosphere, the outer solid crust, oceans, lakes were formed. The average thickness of cooler outer crust is about 30 km. Hot dry rocks, hot gases and liquids are deposited in the region below average depth of 2800 km. The magma­(molten mass) in the temperature range of 1250°C to 1500°C. The centre of the earth is at temperature about 4500°C.

The earth is loosing heat slowly through the outer crust with average energy loss of about 0.025 W/m2.

The earth's outer crust and internal rock formation is non­uniform.­The liquid magma­in the upper mantle approaches earth's surface at some points resulting in higher thermal gradients and higher heat flows through surface of the earth.

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1. Average geothermal gradient app. 30°C/IOOO m.

2. Theoretical increase in boiling point of water with increase in depth allowing for decrease in density of water at higher temperature.

3. Temperature of water in vigorous upflowing spring.

4. Effect of impermeable rock.

5. Leaky spring which discharge large quantities of hot water.

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Hydro-geothermal energy resources

The earth's surface have potential hydro­geothermal­resources­in the form of hot water, wet steam and mixture of hot water and steam of medium temperatures (below 200°C).

The water gets heated and rises through defects in the solid impermeable rocks and gets collected in the fractures within the permeable rocks. The upper impermeable rock provides insulating covering to the hot water deposits.

The hot water deposits without much steam content are called liquid­dominated­hydro­geothermal­deposits.­The temperature of water in such deposits is usually in the range of IOO°C to 310°C.

When wells are drilled in the ground over such deposits, there are three possibilities: -The hot water and steam rises naturally through the production well (Geo-

pressure system). - The hot water should be pumped up through the production well. -Geothermal brine rises through the production well. The geothermal liquid

having high mineral content (calcium chloride, boron. clay, etc.) is called geothermal brine.

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Geopressure Geothermal Resources

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Depth = 3 to10 km

Temperature = 170ºC

Pressure = 135 kg/cm²

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Reference data of a Geopressure hydrothermal aquifer and well

Aquifer,

Depth of reservoir(deposit) 3660 m

Radius of reservoir (deposit) 16 km

Initial pore pressure 680 kg/cm2

Thickness of stratrom 60 m

Rock porosity 20 %

Well diameter (I. D. of pipe ) 23 cm

Production Well

Well diameter (ID of pipe) 23 cm

Temperature of discharge 37 oC

Temperature at reservoir at surface 125 oC

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Hot Dry Rock Geothermal Resources (Petro Geothermal Resources) The hard rock (igneous and crystalline

rock) surrounding the magma is at high temperature. Water does not exist in the surround ings and the heat exists in hot dry rock (HDR).­ The known tempera tures .of hot rocks at useful depths up to 3000 m are between 150°C and 290°C. The HDRs are impermeable. HDR resources represents highest (about 85%) of total extractable geothermal energy deposits in the world.

Technique employed for thermal energy extraction:

- To produce a large fracture (F)­in the hot dry crystalline rock.

- To drill production wells and injection wells up to the fracture cavity.

- To pump in (inject) cold heat transport fluid (generally water) into the cavity of the fracture by means of injection wells.

- To pump up hot water and steam from production well.

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The petro geothermal energy is extracted from Hot-Dry Rock (HRD) at relatively medium depths (2500 m). Fracture cavity is produced inside the rock by one of the following means.

- Fracture produced by high pressure water injected in existing fracture.

- Fracture produced by underground nuclear explosion or under ground chemical explosion.

- The fracture cavity created in the dry hard rock is typically of

-Conical chimney shape produced by explosive techniques, or

- Cylindrical disc shaped produced by high pressure hydraulic techniques.

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Reference data of Petro Geothermal (HDR) Fracture and Well

Depth of production well 2300 m

Depth of injection well 1450 m

Shape of fracture Vertical dish

Depth at bottom of fracture 2400 m

Depth at top of fracture 3300m

Diameter of fracture 900

Volume off fractured cavity 1.27 x 108 m3

Injection fluid pressure 110 kg/cm2

Injection fluid temperature 20 oC

Production fluid pressure 136 kg/cm2

Production fluid temperature 262oC

Merits and Demerits of Petro-Geothermal Energy Power Plants

Merits Operational flexibility

Water flow rate and temperature may be selected by different depths of production wells.

Large heat resources can be tapped.

Several wells can be drilled in the geothermal field to obtain high flow rate essential for large power plants,

Very long life of production wells 10 to 30 years or even more

Demerits Leakage of injected water from

the artificial fracture cavities into underground layers or rock.

High cost of fracture, drill wells etc.

Several mechanical, thermodynamic, metallurgical, economic

Studies are necessary before finalizing the location of plant.

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Types of Geothermal FluidsGeothermal Fluid Type of Turbine, Cycle

Dry steam Steam- turbine cycle

Hot water temperature > 180°C Steam- turbine cycle

Hot water, temperature< 150°C Binary cycle

Hot brine (pressurised) Binary cycle

Hot brine (Flashed) Special Turbine:

- Impact turbine

- Screw expander

- Bladeless turbine

Geothermal Fluids for Electrical Power Plants

The classification of Geothermal Electrical Power Plant is based on

- Type of Geothermal Energy Resource

- Geothermal steam

- Geothermal brine

- Geothermal hot water

- Hot rock.

- Type of Thermodynamic cycle

- Steam Turbine ... Cycle.

- Binary cycle

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Dry­steam­geothermal­sources­are very rare. So far only three such sources have been located.

- The Geysers, USA- Laderello, Italy - Matusukawa. Japan.

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These geothermal plants are operating successfully in a Philippine

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Development of primary energy consumption in Iceland since 1940. The impact of rising oil prices in the 1970s can be seen clearly

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Sectoral share of utilization of geothermal energy in Iceland in 2005. Direct application

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The first modern geothermal power plants were also built in Lardello, Italy The first geothermal power

plants in the U.S. were built in 1962 at The Geysers dry steam field, in northern California. It is still the largest producing geothermal field in the world.

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Flash technology was invented in New Zealand. Flash steam plants are the most common, since most reservoirs are hot water reservoirs. This flash steam plant is in East Mesa, California.

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Power Technology Expected Capacity Factor (%)*

Nuclear 90

Geothermal 86 – 95

Biomass 83

Coal 71

Hydropower 30 – 35

Natural Gas Combustion Turbine

30 – 35

Wind 25 – 40

Solar 25 – 33 (~60 with heat storage

capability)^

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A short glimpse at geothermal power

Principle of EGS system for geothermal power production

Drilling rig at the European R&D site Soultz-sous-Forêts (F)

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Thanks

Introduction - Historical Background - Classification and Types of Geothermal Power Plants - Vapour Dominated (Steam) Geothermal Electrical Power Plant - Schematic Diagram - Thermodynamic cycle on T.S. Diagram - Number of Geothermal Production Wells and Unit Rating - Liquid Dominated (Hot Water) Geothermal Electric Power Plants: Types and Choice - Liquid Dominated Flashed Steam Geothermal Electric Power Plant - Schematic Diagram - Thermodynamic Cycle, T.S. Diagram - Mass Flow and Power per Well: Flashed­ Steam­ Geothermal Power Plant - Double Flashed System: Liquid Dominated Geothermal Plant - Thermodynamic Cycle on T.S. Diagram - Binary­Cycle­Liquid­Dominated­Geothermal­Power­Plants­ - Working Fluids for Binary Cycle Systems - Merits of Binary Cycle Geothermal Power Plant Description of Heber Binary Project in California. USA - Description of East Mesa Binary Cycle Geothermal Power Plant - Liquid Dominated Total Flow Geothermal Power Plant – Petro-thermal­ (Hot­ Dry­ Rock)­ Geothermal Energy Power Plant - Hybrid Conventional and Geothermal Power Plants.

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Geothermal Electric Power Plants

Geothermal Electric Power Plants

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Basic Aspects Regarding Various Types of Geothermal Power Plants

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The following aspects have decisive influence on the rating and configuration of Geothermal Power Plants.Geothermal­Fluid.­Steam, hot water, brine. Temperature and Pressure of the

geothermal fluid at the discharge point of the production well.

Total dissolved minerals and solids in the geothermal fluid (g/kg).

Rate of discharge by production wells (mass flow per well kg/hr).

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Growth of geothermal power plant installed capacity in the world.

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Types of Geothermal Electric Power PlantsType of Plant Geothermal Fluid Type of Turbine

1Vapour dominated geothermal power plants (dry steam type power plant)

-Dry steam at temperature 200°C -Steam turbine

2 Liquid dominated flashed steam type geothermal power plant

-Hot. water and wet steam, At temperature> 10oC -Steam in flashed from the geothermal fluid

-Steam turbine

3Liquid dominated binary cycle geothermal power plant

-Hot geothermal brine at temperature < 150oC

Organic fluid gas turbine

4 Liquid dominated total flow type geothermal power plant

-Hot geothermal fluid (brine) Special turbine driven by hot geothermal brine

5Petro thermal(HDR) Geothermal power plant

-Hot water + steam from production well 280°C

Steam turbine

-Cold water injected into fractured cavity in HDR

6. Hybrid geothermal fossil fueld power plants

-Hot water of Temperature 70oC to 150oC used for preheating the feed water or air

Conventional steamthermal power plant Conventional gas turbine plant

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Countries and Locations of Geothermal Electrical Plants (1985)

Country and Place

Average depth of well

Average Temp. of fluid

Type of Fluid Dissolved solids

Total installed capacity

m C g/kg MW

Chile 650 230 S+W 15 15

El-Salvador 1000 230 S+W 20 95

Iceland 1000 250 S+W 1 63

Italy 700 200 S.S+W - 421

Japan 1000 220 S.S+W 5 300

Mexico BOO 300 S+W 17 180

New Zealand 800 230 S+W 4.5 350

Philippines 920 200 S+W - 665

Turkey 700 190 S+W 5 5

USA 1500 250 S.S+W - 1400

USSR 800 185 S+W 3 64 Annual increase in total installed capacity of geothermal plants is 7% (Approx)

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Historical review of geothermal electric power plants

1904 Larderello, Italy -Electrical power generated from geothermal energy for the 1st time

1914 Larderello, Italy -8.5 MW power plant with steam turbine generation units.

1944 Larderello, Italy -127 MW steam geothermal power plant

1958 Japan/Mexico/Philippinesetc. - geothermal power plant installed

1960 The Geysers, USA -11 MW steam turbine generator unit commissioned

1982 The Geysers, USA -109 MW steam turbine generator unit commissioned. Total plant capacity 909 MW

1979 USA, Italy. Newzealand. Japan. Mexico. El-Salvadore, Iceland, USSR. Philippines. Turkey, Hungary, France

- Total installed capacity 1900 MW

1987 USA -70 MW binary cycle geothermal power plant. Commissioned in California.

1988 The World - Total installed capacity 3500 MW

2000 The World -Total installed capacity 8000 MW to 10,000 MW

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3. Flashed Steam Geothermal Power Plant:

It is a type of Liquid Dominated Geothermal Power Plant. Production well produces mixture of water and steam at temperature more than 180°C and with low content of dissolved minerals.

The geothermal fluid is a mixture of two phases (water and steam). The mixture is passed through a flash separator to obtain dry­steam.­

Steam turbine is the prime mover. Geothermal fluid is flashed to obtain steam.

4. Binary Cycle Liquid Dominated Geothermal Power Plant:

The geothermal fluid is mixture of water and steam at temperature less than 150°C.

The geothermal heat is exchanged with the working fluid of low boiling point in a heat exchanger gas turbine drives the generator shaft.

5. Binary Cycle Geothermal Power Plant with Hot Brine:

When geothermal fluid is liquid with high mineral content, binary cycle similar to (4) is preferred.

- Working fluid of low boiling point and suitable thermodynamic characteristics. Isobutane. Isobutane + isopentane. Freon Ammonia

6. Total Flow Geothermal Power Plant: The entire geothermal fluid is

passed through the special turbine (Impact turbine, Helical screw expander, Bladeless. turbine etc). Such system is used when the geothermal fluid has very high content of­mud, dissolved minerals etc.

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The main differences between conventional steam thermal power plant and a geothermal power plant are:-

1. Geothermal power plants have smaller unit sizes (5 MW, 10 MW, 15 MW), where as the conventional steam thermal power plants have large unit sizes (200 MW, 500 MW. 800 MW).

2. A variety of systems are used in geothermal power plants for extraction of steam from geothermal energy source.

3. Geothermal power plants need a large flow of geothermal fluid (due to lesser temperature and pressure).

4. Geothermal power plants are located on the geothermal field. It is not technically feasible to transport hot geothermal fluid over long distances due to the drop in pressure and temperature.

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Choice of Turbine for Geothermal Power Plant

Heat Source Type of turbine

Dry steam Steam turbine

Hot water (T> 180°C) Steam turbine

Hot water (T < 150°C) Binary cycle

Hot water with moderate solinity Hybrid cycle

Hot brine, pressurized Binary cycle

Hot brine Special turbine

Vapour dominated (Steam) Geothermal Electrical Power Plant

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T=180ºC to 240ºCPressure = 35 bar

Thermodynamic cycle on T.S. Diagram

The segments of the thermodynamic cycle are as follows:

A­: Steam at the bottom of well.

AB:­Slight superheating at point B­due to pressure drop.

BC­: Slight temperature drop in centrifugal separator.

CD­: Expansion through the turbine.

DE­: Condensation in the condenser.

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Comparison of Vapour Dominated Geothermal Power Plant and Coal Fired Steam Thermal Power Plant Dry steam Centrifugal steam separator Steam turbine Electric Generator Consumer

The main differences between the geothermal electric power plants and coal fired steam electric power plants are:-

Geothermal power plants require much larger flow of steam, per kWh of electrical energy generated.

Unit sizes of steam turbine generators. Power available per well is relatively small. The working fluid in conventional steam thermal coal fired power

plant is high temperature high pressure steam produced from clean water with very low particulates and low dissolved solid matters.

Geothermal steam has higher content of particulates and dissolved impurities.

Additional equipment are necessary in geothermal power plants for production of clean steam.

The configuration of power plants and equipment is influenced by the temperatures, pressure, solid particulates and dissolved impurities in the geothermal steam water produced by the production well.

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COMPARISON OF GEOTHERMAL POWER PLANT AND COAL FIRED STEAM THERMAL POWER PLANT

Vapour Dominated Geothermal Power Plant

Cool Fired Steam Thermal Power Plant

Unit sizes of turbine-generator

5MW to 10MW 100 MW to 600 MW

Steam temperature 270·C 500°C

Steam pressure 8 bar 30 bar

Steam per kWh (relative) 2.5X X

Volume of steam (Relative)

50Y Y

Number of Geothermal Production Wells and Unit Rating

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Electrical power rating per well for a vapor dominated geothermal power plant. (Power rating depends on mass flow and temperature of geothermal steam).

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Data regarding the Geysers--Geothermal Steam Power Plant

Name The Geysers

Location Sonoma country, San Francisco, California, USA

Geological situation Jarassic-Cretaceons, graywackes, shales, basalt.

Average drill hole depth 1500m

Maximum drill hole depth 29OO m

Discharge from well Dry steam

Installed capacity total 9OOMW

Power plant size (largest) 110 MW

Power per production well 7.5MW

Type of turbine Steam turbine

- Inlet steam temperature 176oC

- Inlet steam pressure 8.7 bar

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-Liquid dominated geothermal sources are available in many geothermal fields in the world. The choice of geothermal power plant is generating as follows:

Dry steam Vapour dominated (steam) geothermal power plant

Mixture of hot water and steam with low content of dissolved impurities. Temperature> 180oC

Liquid dominated steam turbine geothermal power plant.

Mixture of hot water and steam, Temperature < 150°C with low dissolved impurities

Liquid dominated binary cycle geothermal power plant with heat exchanger and gas turbine.

Mixture of hot water and steam with high content of dissolved impurities

Liquid dominated binary cycle geothermal power plant.

Hot brine (geothermal fluid is hot brine with high proportion of dissolved impurities and particulate impurities)

Total flow geothermal power plant with special turbine.

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GEOTHERMAL ELECTRIC POWER PLANT IN THE WORLD

Country & LocationLocation

Total installed Capacity

Geothermal Fluid

Temp. °C

USA, The Geysers 1100 MW Steam 285

Italy, Larderello 406MW Stearn,

Steam + water260

New Zealand, Weirakai 290MW Steam + water 260

Japan, various sites 1I0MW Steam + water 280

Chile, El Tatio 15MW Steam + Water 260

El Salvador, Ahuchapan 80MW Steam + water 250

Mexico. Cerro Prieto 150MW Steam + water 370

Turkey, Kizildere 1OMW Steam + water 210

Former USSR, Puauzhetsk 7MW Steam + water 200

Iceland, Namaflijali 2.5MW Steam + water 280

Liquid Dominated Flashed Steam Geothermal Electric Power Plants

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T>180°CP~ 35 bar

Thermodynamic Cycle, T.S. Diagram• A : Water in Underground geothermal

deposit (1)

• AB: Drop in pressure in the production well (2)

• BC : Throttling and flashing of steam in the flash steam separator (4)

• CD : Admition of steam to the steam turbine.

• CE: Liquid (brine) from flash separator sent to reinjection well

• DF: Expansion of steam in the turbine (5)

• FG : Condensation of exhaust steam in the condenser (8)

• GH : Admitting the condensate to cooling tower.

• HI: Injection of water into the ground.

• IA : Supply of hot water to the production well.

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T.S. Diagram of a liquid dominated geothermal power plant

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Comparison: Liquid Vs Vapor Dominated Power Plants

Double Flashed System: Liquid Dominated Geothermal Plant

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Thermodynamic Cycle on T.S. Diagram• A : Geothermal fluid in the well in

form of hot water plus steam.

• AB : Drop in temperature in the production well (2) and inlet piping.

• BC : Drop in temperature in first flashed steam separator (4).

• CD : Throttling from first flashed separator into pipe towards steam turbine.

• DI : Expansion of steam in first stage of steam turbine (5).

• CE : Separation of brine in first flash steam separator (4).

• EF: Flashing of steam in second flash steam separator (4')

• FG : Throttling of steam into inlet pipe of second stage of steam turbine (5').

• GJ: Inlet to second stage steam turbine.

• JK: Expansion in second stage steam turbine (5')

• FH : Separation of liquid (brine) in second flash steam separator (4').

• KL: Condensation in the condenser (8).

• LM : Discharge of condensate to ground

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328

T-S diagram of double flashed system geothermal power plant

Binary Cycle Liquid Dominated Geothermal Power Plants

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Working Fluids for Binary Cycle Systems• Isobutane (2-methyl propane) C4HlO

Boiling Point - 10°C, at one atm pressure. • Freon-12 (normal boiling point - 29ºC)• Propane (Normal boiling point - )• Ammonia (NH3), (Normal boiling point - )

Merits of Binary Cycle Geothermal Power Plant

• No problems of corrosion or scaling in the working fluid loop component (Turbine, condenser, heat exchanger.) Scaling and corrosion problems are only confined to the geothermal liquid loop.

• There is no contact between geothermal fluid and the working fluid.

• The geothermal fluid is returned to the earth. Therefore, there are no environmental problem associated with hydrogen sulphide emission.

• Geothermal energy in low temperature brine can be extracted. About 80 percent of geothermal resources in the world are in low and moderate temperature range.

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Liquid dominated total flow geothermal power plant.

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The thermodynamic cycle of the total flow concept is simplerA : Geothermal brine in the well at high temperature. A-B: Drop in temperature in the production well (2) B-C: Expansion of total flow fluid in the special turbine.C-D : Condensing of steam and vapours in condenser (8). D-E: Reinjection of spent fluid in the ground through the reinjection well

The total flow concept has following problems:

1. Brine handling.

2. Scaling and corrosion of turbine, inlet piping, valves etc. due to high temperature corrosive brine.

3. Precipitation of salts on turbine blades and in pipes, valves.

4. Design of special turbine which converts heat in brine into rotary energy.

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Theoretical Comparison of efficiencies of various Liquid Dominated Geothermal Systems

Geothermal (Hot Dry Rock) Geothermal Energy Power Plant

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APPLICATION OF GEO-HYDROTHERMAL RESOURCES IN INDIAField Particulars and Likely Applications

Puga, J & K -Geo-Hydrothermal-115 springs, 50 to 84°C-total discharge 18 kl/h-field area 3 m2 -Borax deposits also present -A few exploratory wells in shallow depths of 110 m have yielded hot water (l35°C) -Applications: - Green house cultivation - Borax extraction - Space heating - Drying of wool - Binary cycle power plants

West Coast Fields, Maharashtra & Gujarat

-Geo-Hydrothermal -18 springs, 34 to 72°C -Some locations with water at 120°C at 200 to 500 m depthsNa-Ca-CI-SO4 contents-Applications: - Green house cultivation - Mashroom farming - Animal husbandary - Biogas production - brewing of low alcohol content beverages - from sugar cane, grapes. - drying of sea-fish

Tattapani Field. M.P -Geo-Hydrothermal-23 Springs, 50 to 98°C-total discharge 3600 l/h -some shallow depth reservoir with water at 80 to 110oC - Applications: - making hardboards from forest and agricultural waste- production of biogas - drying of timber - drying of cotton -drying of fruits and fish - binary cycle power plant

Summary

Geothermal resources are of following types:

-Steam. water, hot dry rock, mixtures.

Production­wells­extract geothermal fluid.

Geothermal­power­plant­converts thermal energy into electrical energy,

Wells upto 3 km are considered to be economical.

The types of geothermal power plants are called

- Vapour dominated (use steam)

- Liquid dominated (use geothermal brine)

- Hot dry rock (use heat in hot dry rock by injecting water and producing hot water/steam).

Thermodynamic­cycles­include

- Total flow concept

- Steam cycle

- Binary cycle

About 20 nations in the world have known geothermal resources. Total installed capacity of geothermal power plants in the world is around 10,000 MW. 04/13/2023Geothermal Electric Power Plants33

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Thank you for kind attention

Introduction - Energy chains - Applications - Historical background Merits and Limitations - Nature of Wind - Planetary and local/day-night winds - Wind energy quantum - Variables and units used in calculations - Wind power density Pw­ - Power Calculations - Power in Wind -Power by turbine - Efficiency - Kinetic energy - incoming velocity Vi­ - Exit velocity Ve- Power, torque, thrust calculations - Solved problems Velocity at different heights - Site selection - Favorable wind speed range - Mean wind velocity - Wind energy - Wind velocity duration Energy pattern factor - Terms and definitions regarding speeds - Summary.

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Wind Energy-Fundamental and Applications

Wind Energy - Fundamentals and Applications

Introduction to Wind EnergyWind power was used

earlier for several centuries for

Propelling ships, Driving windmills, Pumping water, Irrigating fields and Numerous other

purposes like…...-Pumping water - Grinding grains-Driving generator rotors to

produce electrical energy-Operating wood-saw-Stone crushers,

By late 1980s commercial production of wind turbine generators has commenced. Several wind farms have been installed particularly in

Denmark, Canada, Netherlands, Sweden, U.K., U.S.A., Germany, India etc

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Unit ratings of wind-turbine generators can be broadly classified is as follows

Very small 0.5 to 1 kW

Small 1 to 15 kW Medium 15 to 200 kW Large 250 to 1000 kW

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Data of Smith-Putman-Karman Wind Power Plant, USA

Location: Mountain 610 m high Rotor Speed: 28 r.p.m.

Type: Horizontal shaft. Propeller type, 2 blades.

Generator: A.C. Synchronous

Blade Diameter: 55 m (tip-to-tip) Connection: Grid-connected

Rotor Weight: 16 t Year: 1941

Height of Tower: 34 m Operated: 1941 to 1945 Proved Uneconomical

A wind-turbine­converts the kinetic energy in the wind to rotary mechanical energy and drives the gears and the generator shaft. The electrical generator converts the mechanical energy to electrical energy.

Wind­farms­are located in geographical areas which have continuous, steady, favourable wind in the speed range between 6 m/s to 30 m/s. Annual average wind speed of 10 m/s is considered to be very suitable.

Horizontal shaft wind turbine. Vertical shaft wind turbine.

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Sustainable Development : Energy and Environment convergence

– Energy• World is running out of fossil fuel• The last two years has seen highest • Demand for energy is outstripping the growth in

generation capacity– Environmental problems

• Air – Emissions (SOx, NOx, CO, SPM), ozone depletion, global warming

• Water-Acid precipitation, degradation, loss of bio-diversity

– Sustainable development of “Energy + Ecology + Economy”

– Harnessing renewable energy holds the key

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Cumulative Carbon Savings

CumulativeCarbon Savings

(2007-2050, MMTCE)

Present Value Benefits(billion 2006$)

Levelized Benefit of Wind($/MWh-wind)

4,182 MMTCE $ 50 - $145 $ 9.7/MWh - $ 28.2/MWh

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Worldwide… Developments

• Nearly 74,000 MW of wind power capacity has been installed all over the world

• There has been 29% average annual growth between 1997-2006 and a ten-fold increase during this period

• At the end of 2006, Germany had the highest installed capacity of 20,622 MW followed by Spain(11,615 MW), US (11,603 MW) and India (7000 MW)

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Wind Energy Development – India

• Wind Power Potential in excess of 65,000 MW

• 7082 MW set up by March 2007

• Power and energy shortages, RPS regime the main drivers for wind projects

• High industrial tariff is another reason

• A target of 10,500 MW of capacity addition from wind has been proposed till 2012 for the 11th five year plan of the Government of India.

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0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

55000

60000

65000

70000

75000

80000

85000

Cap

acity

(MW

)

United States Europe Rest of World

1. Germany: 21283 MW2. Spain: 13400 MW3. United States: 13223 MW 4. India: 7000 MW5. Denmark: 3134 MW

World total Oct 2007: 82,255 MW

Total Installed Wind Capacity

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Total Installed Capacity in 1947 – 1362 MW

Present Installed Capacity – 121000 MW

Planned Installed Capacity – 240000 MW By 2020Planned Addition Installed Capacity – 10000

MWEvery year.

Power Scenario in India

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Present Energy Mix

Hydro - 24%

Thermal - 67%

Nuclear - 3%

Renewable - 6%

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Renewable Energy PotentialTechnology Units Estimated

Potential

Wind Power MW 45,000

Small Hydro Power (<25MW) MW 15,000

Bio-Mass MW 19,500

Urban & Industrial Waste

MW 1,700

Solar Photo Voltaic MW/Sq Km 20

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0

0.5

1

1.5

2

2.5

3

2003 2004 2005 2006

Year

Gro

wth

rate

ove

r 200

3 Coal

Gas

Nuclear

Thermal (Total)

Wind

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India…developments

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India… capacity­addition

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0

1000

2000

3000

4000

5000

6000

7000

8000

2004 2005 2006 2007

Installed Capacity (MW) – India

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Historical review and Applications of Wind EnergyApplications RemarksTransportations -Ships with sails

-Discontinued after 1930 with development of engine/turbine driven ships

-Several centuries in past.

-Likely to be used for local transport in some sites

Agricultural and Rural

-Windmills for farm use grinding, pumping. wood-saw. lift irrigation etc.

-Since 12th century in China, Europe. -More than 10,000 wind mills were operating in the world during early 1930s.

Electrical power generation

-First commercial use in Denmark 1885

-Several small units 5 to 25 kW in Europe during 1920s.

- First large unit 1.25 MW in USA, 1943. - Large scale use planned in several countries after 1970s . -Present trend• Wind farms with small units rated 150 to 300 kW• Large grid connected units rated 1 MW to 3 MW each

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Merits and Demerits of Wind Energy

Merits of wind Energy Limitations of wind Energy

Important renewable, energy available free of cost Low energy density

Clean pollution free. Favourable winds available only in a few geographical locations away from cities, forests.

Available in many off-shore, on-shore remote areas. Variable, unsteady, irregular, intermittent, erratic, sometimes dangerous, irratic.

Earth receives vast wind energy. Cost effective and reliable wind power generators are being developed

Direction of wind changes and is never constant or regular.

Will help in supplying electric power to remote areas. Wind turbine design manufacture, installation have proved to be most complex due to several variables and extreme stresses.

Will help in energy conservation of non-renewable sources.

Small units are more reliable but have higher capital cost per kWh. Large units require high tech and have less capital cost per kWh

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No pollution Requires energy storage batteries and/or standby diesel generators for supply of continuous power to load.

Low operating cost Solar energy can be directly converted to heat or electricity. Wind energy can be converted into mechanical energy, then to electrical energy.

Economically competitive Wind farms can be located only in vast open areas in locations of favourable wind. Such locations are generally away from load centres.

Ideal choice for rural and remote areas and areas which lack other energy sources.

Wind farms require flat, vacant land free from forests.

Wind energy can be used for obtaining mechanical energy for grinding, Pumping etc. resulting in energy conservation.

Presently high cost per MWhr. In future, the cost is likely to compete with fossil fuel plants in certain areas.

Very clean and pollution-free operation. Only in kW and a few MW range. Does not meet the energy needs of large cities and industry.

Wind Energy Quantum

P α V3

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1 MW Turbine Power Curve

0

200

400

600

800

1,000

1,200

0 2 4 6 8 10 12 14 16 18 20 22 24Wind speed (m/s)

Po

we

r (k

W)

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Wind Turbine Efficiency

etc.fraction spillage, no assuming efficiency l theorticapossible Maximum

turbine windof Efficiency Actual

Wstream, in windpower TotalP

W,by turbinepower RealP

P P

max

a

t

ta

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Turbine of the Le Nordais Windfarm, Quebec, Canada

Coastal Windfarm, DenmarkWindfarm in Palm Springs, California, USA

Substation, California, USA

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Worldwide… TrendsInstalled Capacity

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Worldwide… TrendsAnnual Capacity Addition

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Worldwide… Projections

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0

5000

10000

15000

20000

Year

MW

(cu

mm

)....

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U.S. Electricity Generation by Energy Source, 2004

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Wind As a Percentage of Electricity Consumption

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Power for a TelecommunicationsTower, Arizona, USA

Power for a RemoteVillage, Brazil Hybrid Wind Energy System, Chile

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KPCL Wind FarmKappatagudda

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Schneebergerhof, Germany

Erkelenz, Germany

Brewster, MN

Jutland, Denmark

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Price Trends : Trading

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Wind Capital Cost

0

500

1000

1500

2000

2500

3000

2005 2010 2015 2020 2025 2030

Insta

lled

Cap

ital

Co

st

(2006 $

/kW

)

Land-based

Offshore

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Futu

ristic Desig

ns

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Sum-up

• Wind energy can go a long way to establish the energy security in India

– More than 1,700 MW added in the last financial year – 98% by private sector

• Wind energy can easily meet 5% of total energy generation in India on the shorter run

– Countries like Germany & Denmark have increased this share to as high as 20%

• Instruments like production tax credit would commercialise this source of energy in the near future

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Wind Energy Investors

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Thank You

For

Listening

Wind Turbine-Generator Units

OrientationTurbines can be categorized into two overarching classes based on the orientation of the rotor

Vertical Axis Horizontal Axis

Vertical Axis Turbines

AdvantagesOmnidirectional

Accepts wind from any angle

Components can be mounted at ground levelEase of serviceLighter weight towers

Can theoretically use less materials to capture the same amount of wind

Disadvantages Rotors generally near

ground where wind poorer

Centrifugal force stresses blades

Poor self-starting capabilities

Requires support at top of turbine rotor

Requires entire rotor to be removed to replace bearings

Overall poor performance and reliability

Have never been commercially successful

Lift vs Drag VAWTs

Lift Device “Darrieus”Low solidity,

aerofoil bladesMore efficient

than drag device

Drag Device “Savonius”High solidity, cup

shapes are pushed by the wind

At best can capture only 15% of wind energy

VAWT’s have not been commercially successful, yet…Every few years a new company comes along promising a revolutionary breakthrough in wind turbine design that is low cost, outperforms anything else on the market, and overcomes all of the previous problems with VAWT’s. They can also usually be installed on a roof or in a city where wind is poor.

WindStorMag-Wind

WindTree Wind Wandler

Tip Speed Ratio

Cap

acity Factor

Horizontal Axis Wind Turbines

Rotors are usually Up-wind of tower

Some machines have down-wind rotors, but only commercially available ones are small turbines

Active vs. Passive Yaw Active Yaw (all medium & large

turbines produced today, & some small turbines from Europe)Anemometer on nacelle tells

controller which way to point rotor into the wind

Yaw drive turns gears to point rotor into wind

Passive Yaw (Most small turbines)Wind forces alone direct rotor

Tail vanesDownwind turbines

Airfoil Nomenclaturewind turbines use the same aerodynamic principals as aircraft

Lift & Drag Forces The Lift­Force is perpendicular to

the direction of motion. We want to make this force BIG.

The Drag­Force is parallel to the direction of motion. We want to make this force small.

α = low

α = medium<10 degrees

α = HighStall!!

α

VR = Relative Wind

V

ΩR Ωr

V

α = angle of attack = angle between the chord line and the direction of the relative wind, VR .

VR = wind speed seen by the airfoil – vector sum of V (free stream wind) and ΩR (tip speed).

Apparent Wind & Angle of Attack

Tip-Speed RatioTip-speed ratio is the ratio of the speed

of the rotating blade tip to the speed of the free stream wind.

There is an optimum angle of attack which creates the highest lift to drag ratio.

Because angle of attack is dependant on wind speed, there is an optimum tip-speed ratio

ΩRV

TSR =

ΩR

R

Where,

Ω = rotational speed in radians /sec

R = Rotor Radius

V = Wind “Free Stream” Velocity

PERFORMANCE OVER RANGE OF TIP SPEED RATIOS

• Power Coefficient Varies with Tip Speed Ratio• Characterized by Cp Vs Tip Speed Ratio Curve

0.4

0.3

0.2

0.1

0.0

Cp

12 10 8 6 4 2 0 Tip Speed Ratio

Twist & TaperSpeed through the air

of a point on the blade changes with distance from hub

Therefore, tip speed ratio varies as well

To optimize angle of attack all along blade, it must twist from root to tip

Pitch Control vs. Stall Control Pitch Control

Blades rotate out of the wind when wind speed becomes too great

Stall ControlBlades are at a fixed pitch

that starts to stall when wind speed is too great

Pitch can be adjusted for particular location’s wind regime

Active Stall ControlMany larger turbines

today have active pitch control that turns the blades towards stall when wind speeds are too great

Airfoil in stall

• Stall arises due to separation of flow from airfoil• Stall results in decreasing lift coefficient with increasing angle of attack• Stall behavior complicated due to blade rotation

Rotor Solidity

Solidity is the ratio of total rotor planform area to total swept area

Low solidity (0.10) = high speed, low torque

High solidity (>0.80) = low speed, high torque

R

A

a

Solidity = 3a/A

Betz Limit

Betz Limit

V1

(1) (2)

5926.27

16C max,p

Rotor Wake

Rotor Disc

All wind power cannot be captured by rotor or air would be completely still behind rotor and not allow more wind to pass through.

Theoretical limit of rotor efficiency is 59%

Number of Blades – OneRotor must move more

rapidly to capture same amount of wind

Gearbox ratio reduced Added weight of counterbalance

negates some benefits of lighter design

Higher speed means more noise, visual, and wildlife impacts

Blades easier to install because entire rotor can be assembled on ground

Captures 10% less energy than two blade design

Ultimately provide no cost savings

Number of Blades - Two Advantages &

disadvantages similar to one blade

Need teetering hub and or shock absorbers because of gyroscopic imbalances

Capture 5% less energy than three blade designs

Number of Blades - ThreeBalance of

gyroscopic forcesSlower rotation

increases gearbox & transmission costs

More aesthetic, less noise, fewer bird strikes

Blade Composition Wood

WoodStrong, light

weight, cheap, abundant, flexible

Popular on do-it yourself turbines

Solid plankLaminatesVeneersComposites

Blade CompositionMetalSteel

Heavy & expensiveAluminum

Lighter-weight and easy to work with

ExpensiveSubject to metal fatigue

Blade ConstructionFiberglassLightweight, strong,

inexpensive, good fatigue characteristics

Variety of manufacturing processesCloth over framePultrusionFilament winding to

produce sparsMost modern large

turbines use fiberglass

HubsThe hub holds the rotor

together and transmits motion to nacelle

Three important aspects How blades are

attachedNearly all have

cantilevered hubs (supported only at hub)

Struts & Stays haven’t proved worthwhile

Fixed or Variable Pitch? Flexible or Rigid

AttachmentMost are rigidSome two bladed

designs use teetering hubs

Drive TrainsDrive Trains transfer

power from rotor to the generator

Direct Drive (no transmission)Quieter & more

reliableMost small turbines

Mechanical TransmissionCan have parallel or

planetary shaftsProne to failure due to

very high stressesMost large turbines

(except in Germany)

Direct Drive Enercon E-70, 2.3 MW (right)

GE 2.3 MW (above)

Multi-drive Clipper Liberty 2.5 MW (right)

Rotor Controls“The rotor is the single most critical element of any wind turbine… How a wind turbine controls the forces acting on the rotor, particularly in high winds, is of the utmost importance to the long-term, reliable function of any wind turbine.” Paul Gipe

Micro TurbinesMay not have any

controlsBlade flutter

Small TurbinesFurling (upwind) – rotor

moves to reduce frontal area facing wind

Coning (downwind) – rotor blades come to a sharper cone

Passive pitch governors – blades pitch out of wind

Medium TurbinesAerodynamic StallMechanical BrakesAerodynamic Brakes

TowersMonopole (Nearly

all large turbines)Tubular Steel or

ConcreteLattice (many

Medium turbines)20 ft. sections

GuyedLattice or monopole

3 guys minimumTilt-up

4 guysTilt-up monopole

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Biomass Energy Resources and Conversion Processes

Introduction - Photosynthesis and origin of biomass energy - Biomass Energy Resources - Cultivated Biomass Resources - Waste - to Biomass Resources - Terms and Definitions - Some liquid and gaseous fuels derived from biomass - Important Biomass to Energy Conversion Processes - Direct Combustion(incineration) - Wood and Wood Waste - Harvesting super trees and energy forests - Fluidized Bed Combustion Boilers for Waste Solid Fuel to Heat Conversion - Phyrolysis – Thermo-chemical Biomass Conversion to Energy - Gasification - Anaerobic Digestion - Fermentation - Gaseous Fuel from Biomass - Summary of Biomass Energy Conversion Processes - Summary.

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6 MW Biomass Power project, Andhra Pradesh

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What is Biomass? Biomass energy is energy from the sun captured in

organic materials derived from plants or animals.  Sources of biomass include:

Forestry residues (green waste from landfills, sawmill waste, other vegetative and wood waste)

Agricultural crops grown for energy purposes and other agricultural waste

Woody construction and debris waste Animal waste Ethanol waste Municipal solid waste (sewage sludge or other

landfill organics) Landfill gas Other industrial waste (i.e. paper sludge from paper

recycling processes)

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AVERAGE HEAT CONTENT OF SELECTED BIOMASS FUELS Fuel Type Heat Content Units

Agricultural Byproducts 8.248  Million Btu/Short Ton

Black Liquor 11.758  Million Btu/Short Ton

Digester Gas 0.619  Million Btu/Thousand Cubic Feet

Landfill Gas 0.490  Million Btu/Thousand Cubic Feet

Methane 0.841  Million Btu/Thousand Cubic Feet

Municipal Solid Waste 9.945  Million Btu/Short Ton

Paper Pellets 13.029  Million Btu/Short Ton

Peat 8.000  Million Btu/Short Ton

Railroad Ties 12.618  Million Btu/Short Ton

Sludge Waste 7.512  Million Btu/Short Ton

Sludge Wood 10.071  Million Btu/Short Ton

Solid Byproducts 25.830  Million Btu/Short Ton

Spent Sulfite Liquor 12.720  Million Btu/Short Ton

Tires 26.865  Million Btu/Short Ton

Utility Poles 12.500  Million Btu/Short Ton

Waste Alcohol 3.800  Million Btu/Barrel

Wood/Wood Waste 9.961  Million Btu/Short Ton

   Source: Energy Information Administration, Form EIA-860B (1999), "Annual Electric Generator Report - Nonutility 1999."

Introduction Organic matter derived from biological

organisms (plants, algae, animals etc.) are called Biomass.­The energy obtained from biomass is called Biomass­Energy.­

The raw organic matter obtained from nature for extracting secondary energy is called Biomass­Energy­Resource.­

Biomass energy resources are available from botanical plants, vegetation, algae, animals and organisms living on land or in water.

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431

Biomass resources are broadly classified into two categories:

1. Biomass from cultivated fields, crops. forests and harvested peri odically.

2. Biomass derived from waste e.g., Municipal waste (Urban Rubbish), Animal excreta/dung, forest waste, agricultural waste, bioprocess waste, butchery waste, fishery waste/processing waste etc.

Biomass is considered as a renewable­source­of­energy­because the organic matter is generated every day/year.

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Some Specific points Biomass energy is well known from

Agricultural Age (5000 years B.C.). wood,­cow­ dung­ etc.­ are­ used­ as fuels­particularly­ in­ rural­ and­ tribal­ areas­ in­India.­

The use of waste-to-energy processes by incineration, Biogas, Bio-chemicals etc. is comparatively recent.

Biomass­ energy­ is produced by green plants by photosynthesis­ in presence of sun light. Biomass energy is a result of solar­ energy­ converted to biomass­energy­by green plants.

Fossil­ Fuels­ (Coal, Petroleum Oil and Natural Gases) are produced from dead, buried biomass under pressure and in absence of air during several millions: of years. However, they are considered separately as fossils and are not­included in the category of Biomass.

Biomass­ cycle­ maintains the environmental balance of oxygen, carbon dioxide, rain etc. Hence­Biomass­ Energy­Technology­ is­ an­ Environment­ Friendly­Technology.­

Biomass is being used for production of process heat and electricity, producing gaseous and solid fuels, liquid chemicals etc.

The scope of Biomass Energy is considered in three categories.

- Rural applications of biomass energy.

- Urban and Industrial applications of biomass energy.

- Biomass as a primary source for large scale Electrical Power Generation.

Biomass energy processes serve many purposes. - Energy supply: Fuels, Biogas, Organic Chemicals. - Rural development - Waste disposal - Environmental balance.

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Types of biomass Periodicity of renewal

Urban waste daily

Rural waste (Dung) daily

Agricultural waste and crops

Yearly, six monthly

Forest crops Three to six years

Aquatic crops Three months to one year

The­range­of­these­technologies­couers­plants­of­a few­watts­to a few hundred MW.

For example, a domestic chulha­which burns wood or charcoal is rated less than 2 kW,

a large urban waste incineration power plant is rated 150 MW. Biogas plants are available in sizes from 3 m3/day to 2000 m3/day of biomass feed.

Green plants absorb photo-energy from sun-light. oxygen from air. water and minerals from soil water and produce­organic matter by 'photosynthesis.' The other living organism derive the energy from the green plants (Food). Organic matter from all the living/dead organisms is called Biomass.

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Origin of Biomass

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The biomass­is obtainable from

- land based plants and animals

- aquatic plants and animals

-micro-organisms, algae etc.

The biomass­can be converted to useful secondary energy forms such as

- heat

- gaseous fuels

- solid fuels

- organic chemical

- liquid fuels

Photosynthesis converts solar energy and chemical energy into biomass energy

Waste biomass­serves double purpose

-disposal of waste in a safe, economical and environmentally healthy manner.

- generating useful energy locally from the waste. 04/13/2023Biomass Energy Resources and conversion processes

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rcarbon/yea of tonne102 11

J21103

Biomass Energy Resources Biomass from Cultivated Crops. (Energy farms) Biomass from 'Waste Organic Matter.

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Principal Biomass Energy Resources

Category Name of the

Biomass Source Conversion Process

Cultivated Energy Resource

1. Trees, (Wood chips, saw dusts)

1.1. Burning to produce heat and electricity·

2. Aquatic crops, algae, green plants

1.2. Producing biogas and biochemicals.

3. Agricultural crops 1.3. Production of wood-gas. Wood gasification

4. Fruit farms 1.4. Production of wood. oil and charcoalWood to oil process.

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categoryName of the Biomass Source Conversion Process

Waste-biomass resources from farms and bio-industry

l. Rice and wheat husk

1.5. Production of ethyl alcohol by fermentation of molasses, beet root, fruits. Potatoes, cereals.

2. Bagasse of sugar cane

3. Coconut husk, groundnut shell. straw of rice, wheat etc.

4. Waste of furniture industry, wood industry

5. Waste of poultry industry. Fishery industry, food industry. Brewery tannery, butchery etc.

6.Carbohydrates, glucose, fructose etc.

Waste to Biomass Resources. The waste-to- energy processes convert organic

wastes to intermediate or secondary energy forms such as heat, biogas, alcohol, fuels, chemicals etc.

The waste is classified as - Urban (Municipal) Waste. - Industrial organic waste, Process waste. -Agricultural farm waste. -Rural animal waste. - Forest waste. -Fishery, Poultry, Butchery waste. -Animal and human excreta.

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BIOMASS CONVERSION PROCESS The biomass conversion process (Bio

conversion process) has several routes depending upon temperature, pressure, micro-organisms utilized, process and the culture conditions. These routes are classified in following three broad categories.

Direct Combustion (Incineration) Thermochemical Conversion. Biochemical Conversion.

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Biomass Energy Conversion Processes and End Products

Biomass resource

Conversion Process

Energy Products

Users

l. Dry biomass

(a) Combustion Heat Steam Electricity

- Industry

-Wood - Domestic

- Residue

(b) pyrolysisOil Char Gas

- Industry

- Transport

(c) Hydrolysis and Distillation

Ethanol (Ethyl alcohol)

- Transport

- Industry

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Biomass &source Conversion

Process Energy

Products Users

2. Wet biomass -Sewage Sugars from fruits, beet. molasses

(a) Anaerobic digestion

Methane - industry

- Domestic

(b) Fermentation and Distillation

Ethenol (Ethyl alcohol)

- Transport

- Chemical

3. Water - Photochemical - Photobiological - Catalytic

Hydrogen

- industry

- Chemicals

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S.No. State

upto 31.03.2002 2002-03 2003-04 2004-05 2005-06 2006-07 2007-08 Total

1 Andhra Pradesh 101.20 58.85 37.70 69.50 12.00 22.00 33.00 334.25

2 Chhattisgarh 11.00 -- -- -- 16.50 85.80 17.50 130.80

3 Gujarat 0.50 -- -- -- -- -- -- 0.50

4 Haryana 4.00 -- -- 2.00 -- -- -- 6.00

5 Karnataka 75.60 33.78 26.00 16.60 72.50 29.80 8.00 262.28

6 Madhya Pradesh 0.00 -- 1.00 -- -- -- -- 1.00

7 Maharashtra 24.50 -- -- 11.50 -- 40.00 19.50 95.50

8 Punjab 12.00 10.00 -- -- 6.00 -- -- 28.00

9 Rajasthan 0.00 -- 7.80 -- 7.50 8.00 -- 23.30

10 Tamil Nadu 106.00 -- 44.50 22.50 -- 42.50 12.00 227.50

11 Uttar Pradesh 46.50 -- 12.50 14.00 48.50 -- 22.00 143.50

  Total 381.30 102.63 129.50 136.10 163.00 228.10 112.00 1252.63

STATE-WISE/YEAR-WISE LIST OF COMMISSIONED BIOMASS POWER /  CO-GENERATION PROJECTS

(AS ON 30.09.2007) in MW

COMBUSTION OF BIO-MASS(INCINERATION)

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Dry shredded biomass

Burning

Air

Heat of combustion

Urban waste to energy incineration plants are 1000 to 8000 t/day and 15 to 150 MW installed capacity

THERMOCHEMICAL CONVERSION OF BIOMASS

Biomass is decomposed in thermo-chemical processes having various combinations of temperatures and pressures,

Gasification of Biomass This is carried out by one of the following two processes.

1. Heating the biomass with limited air or oxygen.

2. Heating at high temperature and high pressure in presence of steam and oxygen.

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PYROLYSIS

Biomass can be converted into gases, liquids, and solids through pyrolysis­at temperatures of 500 -900°C by heating in a closed vessel in the absence of oxygen. The pyrolytic­destructive­distillation­of­wood­has­long been used to recover methanol,­acetic­acid,­turpentine­and­charcoal.­Pyrolysis can process all forms of organic materials, including rubber and plastics which are difficult to handle by other processes. The gases produced are a mixture of nitrogen, methane, carbon monoxide, carbon dioxide, and other hydrocarbons. The liquids produced are oil like materials and the solids are similar to charcoal. ­

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BIOCHEMICAL CONVERSION There are two principal conversion processes in Biochemical

Conversion:

1. Anaerobic Digestion Anaerobic digestion is a type of biochemical conversion involving microbial digestion of biomass. The process and end products depend upto the microorganisms cultivated and culture conditions.

An anaerobe­is a microscopic organism that can live and grow without external oxygen or air. It extracts oxygen by decomposing the biomass at low temperatures up to 65°C, in presence of moisture (80%).

Anaerobic digestion of biomass generates mostly methane­and carbon dioxide gas with small impurities such as hydrogen sulfide. The output gas obtained from anaerobic digestion can be

• directly burnt, or • upgraded to superior fuel gas (methane) by removal of C02

and other impurities.

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The residue of the anaerobic digestion may consist of protein-rich sludge and liquid effluents. These can be used as animal feed or for soil treatment after certain processing.

Anaerobic Digestion Technologies are being widened for using following feed stocks:

Urban (Municipal) waste Agricultural biomass (Straw of rice, wheat, sugar cane

bagasse etc.) Forest biomass (Trees, Leaves) Aquatic biomass (algae, water-plants) Human and animal excreta.

In the presence of moisture and the absence of oxygen, most organic materials will undergo natural fermentation in which 60-80% of the carbon in the organic material is converted to a mixture of carbon dioxide, methane,­traces of hydrogen sulfide, and nitrogen.

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FERMENTATION The fermentation is a process of decomposition of organic

matter by microorganisms especially bacteria and yeasts. Examples of fermentation include:

decomposition of grains, sugar to form ethyl alcohol (ethanol) and carbon dioxide by yeast (in making of wine)

ethyl alcohol forming acetic acid (in making Vinegar)

About 15% of ethanol produced in the world is through fermentation of grains and molasses.

Ethanol (Ethyl Alcohol) can be blended with gasoline (petrol) to produce gasohol­ (90% petrol and 10% ethanol). Processes have been developed to' produce various fuels from various types of fermenta tions.

Ethanol­ fermentation­ of biomass occurs at 20 to 30°C. The process takes about 50 hours. Yield is about 90% liquid. This contains about 10 to 20% of alcohol depending upon the tolerance of yeast to alcohol. Concentration of alcohol is increased by distillation.­

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Various Types of FermentationsName of

fermentationIn-feed Products of process

Ethanol fermentation Sugar cane, Sugar beets, molasses, fruit juices, cereals (starch), potatoes (starch), cellulose: Wood

-Ethanol and carbon dioxide

- Ethanol can be blended with gasoline (petrol) to the extent of 10 to 25%

Butanol-Isopropanol Fermentation

Carbohydrates Mixed solvents -n-butane

-Iso-propanol

- acetine

-ethanol

Methane fermentation Acetic acid

Propionic acid

Firmic acid

Lower alcohols

Aldehydes

Ammonia

Hydrogen sulphide

H2 and CO2

Methane and CO2

Hydrogen Fermentation Hydrogen mixed with acids

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Summary of Biomass Energy Conversion Processes

S.No.

Process Input Feedstock Conversion Temperature

Conversion Pressure

Characteristics of Process

Product Form

Process Yield (% of original Mass)

l. Anaerobic fermentation

Aqueous slurry (3-20% solids)

20°C to 50°C Atmospheric Fermentations of wastes or algae grown on wastes of energy crops

50 to 70% Methane Remainder C02

(biogas) 20 to 26%

2. Bio-photolysis

Aqueous slurry for algae, bacteria and/or protein-enzyme complexes

20°C to 500°C Atmospheric Sunlight produces intracellular enzymatic reduction of H2O

Hydrogen

3. Acid hydrolysis

5% acidified slurry (H2S04 with cellulose)

20°C to 50°C Atmospheric Glucose fermented to ethyl alcohol. Cellulose hydrolyzed to glucose

Ethyl alcohol

4. Enzyme hydrolysis

Aqueous slurry (cellulose-rich)

20°C to 50°C Atmospheric Extracellular enzymatic conversion of cellulose to sugar to alcohol

Ethyl alcohol 90%

5. Combustion Dried feedstock (10% to 25% H2O)

1200°C to 1300°C

Atmospheric Augments (i.e. 5 to 20%) boiler fuel (i.e., coal, oil or gas)

Heat, Steam can be converted to electricity.

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6. Pyrolysis Dried feedstock

500 oC > 1300°C

Atmospheric

All of the gas and 1/3 of the char produced is used to supply heat in typical process. Oxygen free environment used.

Oil Char

Gas

40% 20%

7. Chemical reduction

Aqueous slurry (15% solids)

250°C to 400 °C

Uses CO and H2 3/8 of

Product oil used by process

Oil 23%(2 barrels/ton)

8 .

Hydro . Gasification

.

Animal manure (other wastes can also be used)

550°C

Hydrogen atmosphere produced from manure. Purification and methanation of product gas required.

C2H

6 (12%)

40%

CH4 (42%)

CO2 (37%)

or

CH4/C2H6

9.

Catalytic Gasification

!

Dried feedstock, mixed with alkali carbonate (12%-25% by wgt.)

650° to 750°C

Nickel catalysts used for second conversionstep. Inert atmosphere required.

CO2

CH4

orCH4 only

90%

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Biomass and Energy Product in Various CountriesS. No Country Product and Source

1. Brazil (1977) Ethanol from sugarcane (ex distillery) Gasoline (retail)

2. Australia (1975) Ethanol from Cassava Industrial ethanol

3. Canada (1975 & 1978) Methanol from wood

4. Switzerland ( 1980) Combined heal, electricity, steam from Urban Waste incineration Plant

5. New Zealand(1976) Ethanol from pine trees (500 t/day capacity: credits from byproducts)

6. New Zealand (1977) Biogas from plants. Natural gas, Coal gas

7. Upper Volta (976) Fuel wood from plantation ,Kerosene (retail) ,Butane gas (retail) ,Electricity

8. Philippines(977) Electricity from Leucaena fuel wood-fired generating station (same cost as oil-fired. station)

9. Tanzania(1978) Biogas from dung (for cooking and lighting) Electricity

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India (Tamil Nadu) (1978)

Casuarina fuel wood to replace coal-fired electricity generating station

Rural Areas (1980-1990s)

Cow-dung to methane by Gobar Gas Plants. Methane as fuel for rural areas, community centres. Agricultural waste to combined heat and power by FBCB.

Europe USA Australia (1988)

Landfill Biogas Projects 146 Projects. Biogas from Urban Landfill Waste by Anaerobic Digestion. Biogas (methane) used as fuel.

Europe USA Japan (1988)

Waste Incineration Energy Projects 155 projects Urban Solid Waste is burnt. Heat is used for producing steam and electricity.

Europe (1993) Wet Fermentation Process and dry fermentation Process for production of Biogas on large scale from Municipal Solid Waste (MSW) 100 large projects (5000 to 55000 m.t. of MSW per year)

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CONVERSION PROCESSES

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Texas bio -mass energy

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Biomass conversion

direct combustion, such as wood waste and bagasse (sugar

cane refuge)

thermochemical conversion

biochemical con version

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Thermochemical conversion

Gasification:­ ­ takes place by heating the biomass with limited oxygen to produce low heating value gas or by reacting it with steam and oxygen at high pressure and temperature to produce medium heating value gas.

Liquefaction:

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Biochemical conversion

Anaerobic digestion involves the microbial digestion of biomass.The process condition: low temperature= 65°C, and a moisture content = 80 %Products are CO2 + CH4

Impurities: H2S

Fermentation : breakdown of complex molecules in organic compound under the influence of a ferment such as yeast, bacteria, enzymes, etc.

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Wet Processes

Anaerobic digestion: Biogas is produced by the bacterial decomposition of wet sewage sludge, animal dung or green plants in the absence of oxygen. Feed stocks: wood shavings, straw, and refuse may be used, but digestion takes much longer. Yield: kilogram of organic material (dry weight) can be expected to yield 450-500 litres of biogas (9-12 MJ)

Fermentation

Chemical reduction. Chemical reduction is the least developed of the wet biomass conversion processes. It involves pressure-cooking animal wastes or plant cellulosic slurry with an alkaline catalyst in the presence of carbon monoxide at temperatures between 250°C and 400°C. Under these conditions the organic material is converted into a mixture of oils with a yield approaching 50%. If the pressure is reduced and the temperature increased, the product is a high calorific value gas.

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Dry

Pro

cesses

Pyrolysis: Energy-rich fuels can be produced by roasting dry woody matter like straw and wood-chips. As the temperature rises the cellulose and lignin break down to simpler substances which are driven off leaving a char residue behind. This process has been used for centuries to produce charcoal. The end products of the reaction depend critically on the condi tions employed; at lower temperatures-around 500°C--organic liquid predominate, whilst at temperatures nearer 1000'C a combustible mixture of gases results. Liquefaction: Liquid yields are maximized by rapid heating of the feedstock to comparatively low temperatures. The vapours are condensed from the gas stream and these separate into a two-phase liquor : the aqueous phase (pyroligneous acid) contains a soup of water-soluble organic materials like acetic acid, acetone and methanol (wood alcohol)

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Gasification. Pyrolysis of wet biomass produces fuel gas and very little liquid. An alternative technique for maximizing gas yields is to blow small quantities of air or oxygen into the reactor vessel and to increase the temperature to over 1000°C.

Steam gasification. Methane is produced directly from woody matter by treatment at high temperatures and pressures with hydrogen gas. The hydrogen can be added or, more commonly, generated in the reactor vessel from carbon monoxide and steam. Recent analyses suggest that steam gasification is the most efficient route to methanol. Hydrogenation. Under less severe conditions of temperature and pressure (300-400°C and 100 atmospheres), carbon monoxide and steam react with cellulose to produce heavy oils which can be separated and refined to premium fuels.

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Photosynthesis

CO2 + H20 + light + Chlorophyll (H2CO)6 + O2+Chlorophyll (Sugar)

or 6C02 + 12H20 C6Hl206 + 6H20 + 602

The absorbed light is in the ultraviolet and infrared range. Visible light having a wavelength below 700 Å is absorbed by the green chlorophyll

Biogas Generation Biogas, a mixture containing methane =55-65 % carbon dioxide =30-40 % impurities (H2 , H2S, and some N2)

Produced from the decomposition of animal, plant and human waste.

calorific value = 5000 -5500 kcal/kg directly used in cooking by reducing the demand for

firewood.

A few other materials through which biogas can be generated are algae, crop residues (agro-wastes), garbage kitchen wastes, paper wastes, sea wood, human waste, waste from sugarcane refinery, water hyacinth etc., apart from the above mentioned animal wastes. Any cellulosic organic material of animal or plant origin which is easily biodegradable is a potential raw material for biogas production.

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Biogas technology

Biogas technology is concerned to micro organisms. They are called bacteria, fungi, virus etc. Bacteria again can be classified

beneficial bacteria: Compost making production of biogas, vinegur, etc.

harmful bacteria : Bacteria causing cholera, typhoid, diphtheria are examples of harmful bacteria. This type of bacteria which cause disease both in animals and human beings is called pathogen.­

Bacteria can be divided into two major groups based on the oxygen requirement. Those which

grow in presence of oxygen are called aerobic­

grow in absence of gaseous oxygen are called anaerobic.­

This anaerobic digestion consists broadly of three phases:

(i) Enzymatic hydrolysis cellulosic biomass are broken down into simple compounds.

(ii) Acid formation complex organic compounds are broken down to short chemical simple organic acids.

(iii) Methane formation organic acids as formed above are then converted into methane (CH4) and CO2 by the bacteria (methane fermentors)which are strictly anaerobs.

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Advantages of anaerobic digestion

1. Calorific value of gas

2. New sludge production

3. Stable sludge. 4. Low running cost. 5. Low odour. 6. Stability. 7. Pathogen reduction8. Value of sludge. 9. Low nutrient

requirement.

Factors affecting Biodigestion

1. pH or the hydrogen-ion concentration:

6.5<pH>7.5 micro organism will be very active

4<pH>6 acidic

9<pH>10 alkaline

2. Temperature

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CH4 productio

n

3. Total solid content of the feed material : It should be 1 : 1 by weight

4. Loading rate : MST plants operate at loading rate of 0.5 – 1.6 kg

5. Seeding :

6.Uniform feeding:

7.Diameter to depth ratio 0.66 to 1.0

8.Carbon to Nitrogen ratio C/N=30

9.Nutrients :

10. Mixing or stirring or agitation of the content of the digester

11. Retentation time or rate of feeding 45 - 60 days

12. Type of feed stocks Ca, Mg, K reduces the production

13. Toxicity due end product

14. Pressure It must be low

15. Acid accumulation inside the digester pH of the sludge reduces

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Classification of Biogas Plants1. Continuous and batch types (as per the process).Continuous plant

Single­stage­process

The main features of continuous plant are that: It will produce gas continuously; It requires small digestion chambers It needs lesser period for digestion; It has less problems compared to batch type and it is easier in

operation.

Double­stage­process:­

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The batch Plant: The feeding is between intervals, the plant is emptied once the process of digestion is complete. In this type, a battery of digesters are charged along with lime, urea etc. and allowed to produce gas for 40-50 days. The biogas supply may be utilized after 8-10 days.

The main features of the batch­plant­are : (i) The gas production in it, is intermittent, depending

upon the clearing of the digester.

(ii) It needs several digesters or chambers far continuous gas production, these are fed alternately.

(iii) Batch plants are good for long fibrous materials.

(iv) This plant needs addition of fermented slurry to start the digestion process. There may be a direct change to the acid phase in absence of the fermented slurry, which affects formation of methane.

(v) This plant is expensive and has problems comparatively, the continuous plant will have less problems and will be easy for operation.

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2. The dome and the drum types.(i) The floating gas holder plant: Known as KVIC plant(ii) Fixed dome digester: Chinese plant

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Advantages of Floating Drum Plant :

(1) It has less scum troubles because solids are constantly submerged.

(2) No separate pressure equalizing device needed when fresh waste is added to the tank or digested slurry is withdrawn.

(3) In it, the danger of mixing oxygen with the gas to form an explosive mixture is minimized.

(4) Higher gas production per cu m of the digester volume is achieved.

(5) Floating drum has welded braces, which help in breaking the Cum (floating matter) by rotation.

(6) No problem of gas leakage.

(7) Constant gas pressure.

Disadvantages of Floating Drum Plant :

(1) It has higher cost, as cost is dependent on steel and cement.

(2) Heat is lost through the metal gas holder, hence it troubles in colder regions and periods.

(3) Gas holder requires painting once or twice a year, depending on the humidity of the location.

(4) Flexible pipe joining the gas holder to the main gas pipe requires maintenance, as it is damaged by ultraviolet rays in the sun. lt may be twisted also, with the rotation of the drum for mixing or scum removal.

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Advantages of Fixed Dome Type Plant

(1) It has low cost compare to floating drum type, as it uses only cement and no steel.

(2) It has no corrosion trouble.

(3) In this type heat insulation is better as construction is beneath the ground. Temperature will be constant.

(4) Cattle and human excreta and long fibrous stalks can be fed.

(5) No maintenance.

Disadvantages Fixed Dome Type Plant

(1) This type of plant needs the services of skilled masons, who are rather scarce in rural areas.

(2) Gas production per cum of the digester volume is also less.

(3) Scum formation is a problem as no stirring arrangement.

(4) It has variable gas pressure.

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3. Different variations in the drum type.

Two main variations in the floating drum design

One with water seal and the other without water seal. Water sealing makes the plant complete -- anaerobic and corrosion of the gas holder drum is also reduced.

The other variations are of materials used both in construction of the digester and the gas holder.

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Commonly used Biogas plants in India

(1) Fixed Dome Biogas plant, examples are Janta Biogas plant and Deen bandhu Biogas plant.

(2) Floating gas holder plant, examples are Khadi and Village Industries type Biogas plant, Pragati Design biogas plant, Ganesh Biogas plant, Ferro-cement digester biogas plant.

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Community Biogas Plants

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Flow sheet of a community Biogas plant for a village

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Possible energy conversion routes and productions from biomass

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Urban Waste-to-Energy by Incineration Process and Energy from Incineration of Wood

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Composition of Municipal solid waste in Mumbai

15%0.75%

0.80%

0.40%

35%

37.50%

10.55%

Paper and cardboardPlasticsMetals (ferrous)GlassSand & fine earthCompostable matterOthers

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WTE plants located in the heart to the city. Such energy plants are rated in MW range (50 to 200 MW) and serve the following functions

Safe and economical disposal of urban waste.

Supply of electrical and thermal energy to the consumers 10 the city.

Environmental protection from urban waste

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Waste Material % Waste Material %

Paper 51 Plastic. rubber 4

Food-rubbish 20 Wood 2

Metal-scrap 10 Textile 2

Glass 9 Miscellaneous 2

Typical Composition of Urban Waste in Europe

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7

Waste-to-Energy Incineration Process

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8

Bio mass energy from

nature

Thermal energy from

incinerator

Mechanical energy

from steam

Electrical energy from

generator

Electrical Energy to user or grid

Choice of In-feed, Range and Location of Plants

The incineration Process accepts a wide variety of biomass inputs including:

Semi dried wood, trees, tree residues, wood-chips, saw-dust Semi dried garbage (urban waste). Semi dried farm waste (dried cow-dung, straw, sugar,

bagasse, etc. Mixtures of fossil fuels and biomass for higher heat content

of the in feed. Steam is supplied to steam-turbine power plant (50 to

150MW) Heat (hot water) is supplied for district heating in cold

countries. Steam is supplied to process industry.

04/13/2023Biomass Energy Resources and conversion processes52

9

Location of the waste to power plant

In Feed Location or Plant Output

Forest Produce

- Trees, tree residue Forest Electric power

- Wood Near furniture industry Heat/steam for

- Wood waste furniture industries

Sugar bagasse Near sugar Electric power

producing plants Hent, steam for

sugar plant

Urban waste In a large city Electric power

Heat and steam for

urban consumer

04/13/2023Biomass Energy Resources and conversion processes53

0

04/13/2023Biomass Energy Resources and conversion processes53

1

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2

WTE Plant for UW Incineration

04/13/2023Biomass Energy Resources and conversion processes53

3

04/13/2023Biomass Energy Resources and conversion processes53

4

Environmental Considerations The Urban Waste-to-Energy plants have to meet

stringent standards of pollution control regulations. The typical limiting­ values­ of­pollutants­ discharged by a Waste-to-Energy Plant are:

04/13/2023Biomass Energy Resources and conversion processes53

5

The equipment provided in a typical power plant for controlling pollutants are:

• Electro-Static Precipitators (ESP)For controlling particulates

• Bag house Filter For controlling particulates

• NOx Scrubber For removal of NO x­

• Chemical treatment For removal of chemicals such as HCL, SOx

04/13/2023Biomass Energy Resources and conversion processes53

6

Fluidized Bed Combustion Boilers (FBCB) for Burning Solid Biomass and Fossil Fuels

Fluidized bed is a layer of solid particles of fuel and ash in tur bulent motion of air-swirl forced into the bed from bottom. Solid pieces of fuel are added in the bed and gets burnt.

Biomass burning process has been simplified by FBCB. Fluidized Bed Technology has been developed during 1970s and has become very successful all over the world for burning solid fuels.

Heat is produced by swirling churning solid particles (ash) (which are only about 99% of bed). Fuel particles constitutes only 1% of bed volume, gets heated and burnt.

Heat is transferred to water and steam flowing through the tubes which are in intimate contact with the solid particles. Some tubes are in the path of hot gases.

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7

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8

Advantages of FBCB1. Coal burnt in the presence of limestone at relatively low

temperatures does not give objectionable SOx, NOx etc.

2. Lower temperatures (app. 850 °C) gives lesser SOx, NOx and longer life of materials, reduces maintenance cost.

3. A variety of fuels can be accepted.

4. Quick cold start with auxiliary fuel burners and slightly slower start without auxiliary burners.

5. No need for costly pollution control equipment for SOx, NOx removal.

6. Lower installation cost maintenance cost.

7. Low objectionable emission products. Hence can he located in the large cities.

8. Calcium oxide in limestone absorbs sulphur oxides (Sox). Fly ash is collected by ordinary fly ash collecting equipment such as fabric filters.

9. Superheated steam even at low ends.

10. No pulverization of coal is needed. Small pieces upto a few cm. dia. of coal can be used.

11. Can be used with combined cycle power plants for giving heat to HRSG and producing steam.

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540

Thank youFor

Kind attention

04/13/2023541

Ocean Energy Technologies

Ocean Energy Technologies

Specific pointsThe oceans, large lakes and bays are huge reservoirs of various

useful and renewable­energy­resources.­World's total estimated ocean energy reserves are about 130 x 106 MW.

Ocean is a great collection of salt water that covers approximately 70% of earth's surface. Five principal oceans are:

Indian Ocean Pacific Ocean Atlantic Ocean Arctic Ocean Antarctic Ocean

The Oceanography­is the science which deals with the­environment­in­the­oceans­including­the­waters,­depths,­beds, biomass, energy resources etc.

04/13/2023Ocean Energy Technologies542

The important ocean energy conversion technologies under active consideration include:

Ocean Biomass EnergyOcean Wave Energy Ocean Geothermal Energy Ocean Salinity Gradient energyOcean Tidal Energy Ocean Thermal Energy Ocean Chemical Energy These technologies are based on entirely

different principles of energy conversion. 04/13/2023Ocean Energy Technologies54

3

Ocean 'Wave Energy refers to the waves of water from ocean to the shore. Ocean waves occur due to the rotation of earth and the winds over ocean surface.

Ocean Thermal Energy refers to the thermal energy acquired by the ocean water from solar radiation.

Ocean Biomass Energy refers to aquatic organic matter such as algae, kelp, and water hyacinths grown in oceans and lakes, marine animals and fishes etc.

Ocean Tidal Energy refers­to­the­hydro-energy­in­ocean­tides.

­Ocean Salinity Gradient Energy

is a type of chemical energy. The salinity of ocean water differs from that of river water. The difference in salinity can be used for generating electrical energy directly from ocean water.

Ocean Wind Energy refers to off shore wind energy resources over oceans.

Ocean Nuclear Energy Resources refers to nuclear energy resources obtainable from ocean water or ocean beds.

Ocean Geothermal Energy refers to geothermal energy available from off shore geothermal fields.

04/13/2023Ocean Energy Technologies544

Ocean­Chemical­Energy­refers to the chemical energy in ocean water. Ocean water contains Sodium, Chlorine, Hydrogen, Oxygen, Iodine, etc. Ocean Chemical Energy is converted to useful secondary energy forms by

Photochemical processes, fuel cells. Photo biological conversion processes. Hydrogen and nitrogen are obtained from

these processes. These are used as fuels and oxidants in fuel cells.

Electrical energy is obtained from fuel cells. 04/13/2023Ocean Energy Technologies54

5

04/13/2023Ocean Energy Technologies546

04/13/2023Ocean Energy Technologies547

Biogss plant. Biogas and other products to consumers

ocean Ocean salinity power plant Electric power

Salinity convertor DC to gradient Cells of fresh and AC

saline water Electric power Series/Parallel to consumers connections

Ocean Ocean current energy Electrical

current converter energy to energy - Turbine consumers

- Generator

Ocean Photochemical conversion Chemical fuels

Chemical oxygen Energy Photo bio conversion hydrogen

Fuel cells or Electrical Energy convertors energy for

consumption

04/13/2023Ocean Energy Technologies548

Type of Ocean Energy Total of World Potential

MW Present installed

Capacity

Ocean Thermal (OTEC) 10,000,000 Negligible Ocean Waves 5,000,000 Negligible Ocean Tides 200,000 250 Ocean Currents 50,000 nil Ocean Salinety Gradient 3,540,000 nil Off-shore Geothermal (for 100 years) 30,000,000 nil Ocean Biomass Resources 800,000 Negligible Ocean Uranium Resources 80,000,000 Negligible

Total World Power 129,590,000 MW

Current utilization of all type 1000MW

Potential of Renewable Power Sources in the Ocean in terms of Total Power in MW

Ocean Energy Resources Ocean Thermal EnergyThe solar energy absorbed by all the oceans in the

world is estimated at 2000 EJ/yr. Only a small fraction of this energy is recoverable (l EJ/yr).

Ocean Thermal Energy Converter (OTEC) converts ocean thermal energy to electrical energy. The total potential of ocean thermal power plants in the world is 10,000,000 MW. However, considering techno economic difficulties, only a small fraction of about 5000 MW may be recoverable in near future. Present use of OTEC is negligible.

04/13/2023Ocean Energy Technologies549

OTEC processes are of two distinct types

1. Flashed steam, steam­turbine­cycle­OTEC Plant using steam water as working fluid, (open cycle OTEC)

2.­­­­­Binary­cycle­OTEC­plant­based on working fluid of low boiling point (e.g.­NH3, Propane) and special turbine (closed cycle OTEC)

In the first alternative, warm ocean water is directly flashed to steam and steam turbine generator delivers energy.

In the second alternative warm water gives heat to working fluid.

In both the types, cold water from bottom of ocean is used for condenser. Major problems in OTEC plants are: Corrosive sea water. Large size of heat exchanger and large volumes' of sea water to be circulated. High installation costs. Low temperature­of ocean water. low efficiency of thermal cycle. High cost of electrical energy obtained from OTEC plants. Large commercial plants based on acceptable OTEC Technologies have not

been built yet (1993) 04/13/2023Ocean Energy Technologies55

0

Advantages and Limitation of Ocean Energy Conversion Technologies

Though ocean energy resources are enormous, only a negligible portion is being recovered.

Ocean energy resources are with low energy density. They are intermittent. Large water must be circulated through the energy conversion plant to extract­

the energy. This requires a larger plant with lower power rating. Ocean water is corrosive. Special materials, surface coatings are required to

prevent corrosion. Ocean energy plants require costly civil works. Ocean energy from high seas requires costly off-shore energy conversion plant and Submarine HVDC of electric power to shore. Presently, the cost of electricity from ocean energy plants is not competitive. The merits of ocean energy technologies are:

Renewable energy available in very large quantities in many parts of the world. Technologies have been developed on pilot scale successfully during 1980s. Considering depleting fossil fuels and increasing cost of fossil fuels, ocean

energy resources provide a viable alternative. Commercial ocean energy conversion plants are being planned and installed

under various schemes of Non-Conventional Renewable Energy. These plants wiII supply useful energy during coming decades.

04/13/2023Ocean Energy Technologies551

The various ocean energy technologies are presently in infant

stage. The ocean energy technologies are characterized by

Small and medium plant capacities (50 kW to 100 MW) Higher capital cost, often prohibitive. Long distances from on-shore load centers. Require favourable topology, geology, ecology. Intermittent nature of ocean waves, ocean tides,

resulting in low average energy output of the plants.

Only 1/6 to 1110 of available energy may be recoverable. Costly HVDC technology is required for transmission of

power from off-shore plant to load centre on land. High cost of electrical energy, generally non-competitive.

04/13/2023Ocean Energy Technologies552

Ocean Energy Routes

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Thank you for kind attention

Ocean Thermal Energy Conversion Plants (OTEC) convert thermal energy from ocean water to electrical power. OTEC cogeneration­plants deliver electrical energy and fresh water.

OTEC Technology is in infant stage. Conceptual designs of open cycle OTEC plants and closed cycle OTEC plants have been finalized. The unit size of turbine generators are in the range of 10 MW to 50 MW. The plant ratings are of 50 MW and 100 MW.Electric energy generated in the OTEC ship Plant

will be used on the board of the ship itself for -Extracting and converting biomass energy into methane,

hydrogen etc.

04/13/2023Ocean Energy Technologies557

Ocean Thermal Energy Conversion

Principle of OTEC

04/13/2023Ocean Energy Technologies558

1

21

T

TTC

Two types of OTEC system under active consideration are,

1. Open­Cycle­(Claude cycle, steam cycle) In Open­ Cycle,­ the warm ocean water is converted into, steam in an evaporator. The steam drives steam-turbine­ generator to deliver electrical energy.

2.­Closed­Cycle­(Anderson Cycle, Vapour Cycle) In Closed­ Cycle,­ the ocean thermal energy is given to liquid working fluid (Ammonia, butane or Freon). Vapour of the working fluid drives vapour­ turbine­generator to deliver electrical energy.

04/13/2023Ocean Energy Technologies559

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Efficiency of OTEC plantsDue to low efficiency, the OTEC plants should

have • Large­intake­of­warm­water­requiring large

pipe line, pumps, heat exchanger, larger size of power plant per kW rated generation.

• The cost of plant per kW is prohibitively high. • High cost of generation (Rs./kWh) • Limited unit capacity of turbine generator unit

(25 kW). • Large number of units required to obtain large

power of 100 MW, 500 MW. 1000 MW etc. required for network. 04/13/2023Ocean Energy Technologies56

2

Open Cycle (Steam Cycle OLTC)

04/13/2023Ocean Energy Technologies563

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Limitation of Open Cycle OTEC System

Very large flow of ocean water in terms of mass and volume. Turbine operates at very low steam pressure. Specific volumes are very

large (2000 times that of fossil fuel plant). Turbine is physically large. Cost of plant is high. Cost of electrical energy from open cycle OTEC is very high. Hence, such

plants are not economically viable at present. Plant is subjected to ocean storms, high waves, etc. The plant is subjected

to extremely

severe stresses Corrosion of metal parts due to saline water. Erosion of metal parts due to

particles in flowing water. Algae and kelp grows in pipes and obstructs water flow. Salts get deposited in pipes and equipment. Maintenance is difficult. Construction of floating power plants is difficult. Power transfer from off-shore OTEC plant to land based load centre is

difficult and costly Plant size is limited to about 100 MW due to large size of components. 04/13/2023Ocean Energy Technologies56

6

Historical Review of Open Cycle OTEC Plants

First OTEC Plant, Cuba, 1929 built by Claude. Second Plant built by French company, Energy

Electrique at Abidjan, Ivory Coast, Africa, 1950.

First OTEC plant planned in India is based on open cycle principle.

India's First Ocean Thermal Energy Conversion (OTEC) Plant in KuIasekharapatnam, Tamil Nadu

04/13/2023Ocean Energy Technologies567

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Closed Cycle OTEC (Anderson Cycle, Vapour Cycle)

04/13/2023Ocean Energy Technologies569

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Combination of hydrogen production by seawater electrolysis and carbon dioxide methanation

04/13/2023Ocean Energy Technologies574

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Many Thanks to All

04/13/2023579

Hydro Energy

IntroductionThe kinetic energy of flowing water as it

moves downstream. Turbines and generators convert the energy into electricity, which is then fed into the electrical grid to be used in

homes, businesses, and by industry.World's hydro energy resources are

enormous (2000000 MW), however only about 25% have been exploited so far. (1994). 04/13/202358

0Hydro Energy

04/13/2023581

Hydro Energy

04/13/2023582

Hydro Energy

04/13/2023583

Hydro Energy

Merits and Demerits of Hydro-Electric EnergyHydro-energy is a clean­ and renewable­ energy.­ The

hydroelectric power generation does not produce pollution. The hydro energy is renewed­naturally­by rain-water and by melting of snow on high mountains during summers.

The natural renewable energy is stored­ in the high level reservoir and used whenever necessary. In this regard. it is different from the solar and wind energies which can not be stored in huge quantities.

Very huge Hydro-electric power plants in range of several hundred to a few thousand MW rating are operating satisfactorily with lowest operating costs and no pollution in several nations in the world (35, 1000MW, some of them are 5000MW). Hydro-Energy Technology is environment-friendly, renewable and simple.

04/13/2023584

Hydro Energy

Transport of raw energy is natural by gravity. The other fossil fuelled power plants have to depend

on transportation of fuel upto power plant. The operating cost of hydro electric power plants is low

and the renewable energy resource occurs free of cost. The price rise of fossil fuels does not affect the price of hydro energy.

The life of hydro-electric plants is 40 to 80 years. They do not become obsolete.

Initial capital cost is high and construction periods are long for conventional large Hydro-Electric Power Plants.

Large hydro potential is usually away from load centers and additional investment is necessary for transmission of bulk power from large remote hydro-electric power plants to distant transmission network.

04/13/2023585

Hydro Energy

Hydro-electric power plants have operational­flexibility.­They can be started quickly, stopped quickly. Auxiliaries are simple. Hydro-electric plant can be operated as a base load plant or a peak shaving plant.

Hydro-Thermal coordination helps in conserving precious fossil fuels and utilizing natural water during monsoon (or summer water from snow).

Hydro reservoirs are multipurpose.­The reservoirs are neces sary for supplying water for drinking, irrigation, industries, power plants, fisheries, aqua-bio energy farms, forests etc. and the water let out from tail race is usable for these multipurposes. Thus the electric power is received as a renewable bonus.

04/13/2023586

Hydro Energy

Primary Hydro Energy Resources in the World

04/13/2023587

Hydro Energy

04/13/2023588

Hydro Energy

The exploitable hydro resources in the world are enormous. The total estimated Hydro-electric resources in the world are 2261000 MW. The estimated exploitation in terms of installed capacity by year 2000 will be 553,800 MW, i.e. 24.49%.

India stands seventh in the serial list of nations with hydro Resources. India's total exploitable hydro resources are 70,000 MW and exploitation by year 2000 will be about 30 1OO MW.

The percentage of unexploited hydro resources is higher in less developed in Asian and African countries. Hydro energy resources are available for exploitation, the hydro schemes involve huge capital outlay spread over several years, though running cost is very low.

Presently the energy strategies are in favour of rapid growth of fossil fuel plants followed by slow growth of long term Hydro- Electric Schemes. This strategy has resulted in environmental problems and drain in foreign exchange.

04/13/2023589

Hydro Energy

Hydro Thermal Nuclear NCR Total

Installed MW 22000 47000 5000 150 74150

% of Total 29.6 63.38 6.74 0.2 100%

Break-up of India's Electrical Energy Generation (1990)

04/13/2023590

Hydro Energy

Auerage Storage Storage Storage Total

Basin Annual Flow Completed On going Planned Storage

cubic kilometres l. Ganga 501 32 15 7 54 2. Brahmpulra 628 0.47 0.83 46 47 3. Godavari 119 19 12 2 33 4. Mahanadi 67 9 5 12 26 5. Narmada 40 3 14 1 18 6. Drahmani, 36 1 3 6 10

Baitarani 7. Other Rivers 469 78 30 7 117

All Rivers in India 1860 143 80 82 305 7.6% 4.3% 4.4% 16%

Data or Annual Flow and Storage on Selected Flood Proms Rivers in India

Hydro electric projects rated upto 15 MW are covered under Nonconventional Energy Resources Schemes. The total potential of small hydro resources in India is about 9000 MW (about 9% of total exploitable hydro resources).

04/13/2023591

Hydro Energy

Types of Hydro-Electric Plants and Energy Conversion Schemes

The most common method of classifying the types of Hydro Electric Power Plants is on the basis of available­head­of­water­between the reservoir level and the turbine tail race level. - High head (more than 150 m) - Medium head (200 m to 150 m) - Low head (2 m to 20 m)

04/13/2023592

Hydro Energy

Energy reserve in the reservoir is proportional to the head (H) of water and quantity (Q) of water in the reservoir.

04/13/2023593

Hydro Energy

Recently, the small, mini, micro hydro power plants have been given priority by Energy Planners.

The classification is as follows: Small Hydro (Less than and upto 15 MW) Mini Hydro (upto 1 MW)) Micro Hydro (upto 100 kW)

Note: World’s largest Hydro-Electrical Power Plant rated 12000 MW.A single hydro power plant delivers about 12000 MW. A coal fired thermal power plant of such a capacity would result in environmental pollution beyond permissible limits.

04/13/2023594

Hydro Energy

04/13/2023Hydro Energy595

04/13/2023Hydro Energy596

04/13/2023Hydro Energy597

Hydro-turbine are classified as : Impulse Type (Pelton) .. for high head:

water from high­head­received with high velocity and high kinetic energy impinges on the buckets of the wheel and the wheel rotates.

Reaction Type (Francis and Kaplan), .. for medium and low head: the water glides over the curved blades and pushes the blades. Water does not­strike the blades

Reaction Types has further two versions: Reaction Type Francis­and Propeller Type: Kaplan.­

04/13/2023Hydro Energy598

HYDRAULIC TURBINES

04/13/2023Hydro Energy599

04/13/2023Hydro Energy600

Pelton-type impulse turbine with housing cover removed

04/13/2023Hydro Energy601

04/13/2023Hydro Energy602

Impulse Turbines - Pelton Wheel

04/13/2023Hydro Energy603

Reaction Turbines - Francis Turbine - Centrifugal Pump

04/13/2023Hydro Energy604

PELTON -impulse turbines TURGO -impulse turbine

BANKI - It is also called CROSS-FLOW and it is an impulse two-stage turbine.

04/13/2023Hydro Energy605

BULB TURBINE- reaction turbine

KAPLAN-reaction turbines and they are divided into two types: double (true KAPLAN) or single (semi-KAPLAN) regulation

FRANCIS-reaction turbine

04/13/2023Hydro Energy606

04/13/2023Hydro Energy607

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Merits of Hydro Turbines Quick starting, loading, stopping. Flexibility of operation. Excellent peaking performance. Suitable for remote. rural, agricultural areas. Efficiency of turbine is very high. Long service life. Low operating cost. Requires few operating staff. Civil construction is simple and compact with local

materials and labour. Can be constructed to augment existing hydro-electric

schemes. Standard Schemes with Standard Turbines of wide

choice. The suitable type is selected. This eleminates delays.

04/13/2023Hydro Energy611

04/13/2023Hydro Energy612

04/13/2023Hydro Energy613

614

Hydropower

615

Course OutlineRenewable

Hydro PowerWind EnergyOceanic EnergySolar PowerGeothermalBiomass

SustainableHydrogen & Fuel CellsNuclearFossil Fuel InnovationExotic TechnologiesIntegration

Distributed Generation

616

Hydro Energy

617

Hydrologic Cycle

http://www1.eere.energy.gov/windandhydro/hydro_how.html

618

Hydropower to Electric Power

PotentialEnergy

KineticEnergy

ElectricalEnergy

MechanicalEnergy

Electricity

619

Hydropower in Context

620

Sources of Electric Power – US

621

Renewable Energy Sources

Wisconsin Valley Improvement Company, http://www.wvic.com/hydro-facts.htm

622

World Trends in Hydropower

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

623

World hydro production

IEA.org

624

Major Hydropower Producers

625

World’s Largest Dams

Ranked by maximum power.

Name Country YearMax

GenerationAnnual

Production

Three Gorges China 2009 18,200 MW

Itaipú Brazil/Paraguay 1983 12,600 MW 93.4 TW-hrs

Guri Venezuela 1986 10,200 MW 46 TW-hrs

Grand Coulee United States 1942/80 6,809 MW 22.6 TW-hrs

Sayano Shushenskaya Russia 1983 6,400 MW

Robert-Bourassa Canada 1981 5,616 MW

Churchill Falls Canada 1971 5,429 MW 35 TW-hrs

Iron Gates Romania/Serbia 1970 2,280 MW 11.3 TW-hrs

“Hydroelectricity,” Wikipedia.org

626

Three Gorges Dam (China)

627

Three Gorges Dam Location Map

628

Itaipú Dam (Brazil & Paraguay)

“Itaipu,” Wikipedia.org

629

Itaipú Dam Site Map

http://www.kented.org.uk/ngfl/subjects/geography/rivers/River%20Articles/itaipudam.htm

630

Guri Dam (Venezuela)

http://www.infodestinations.com/venezuela/espanol/puerto_ordaz/index.shtml

631

Guri Dam Site Map

http://lmhwww.epfl.ch/Services/ReferenceList/2000_fichiers/gurimap.htm

632

Grand Coulee Dam (US)

www.swehs.co.uk/ docs/coulee.html

633

Grand Coulee Dam Site Map

634

Grand Coulee Dam StatisticsGenerators at Grand Coulee Dam

Location Description NumberCapacity

(MW)Total (MW)

Pumping Plant Pump/Generator 6 50 300

Left PowerhouseStation Service Generator 3 10 30

Main Generator 9 125 1125

Right Powerhouse Main Generator 9 125 1125

Third PowerhouseMain Generator 3 600 1800

Main Generator 3 700 2100

Totals   33   6480

635

Uses of Dams – US

Wisconsin Valley Improvement Company, http://www.wvic.com/hydro-facts.htm

636

Hydropower Production by US State

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

637

Percent Hydropower by US State

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

638

History of Hydro Power

639

Early Irrigation Waterwheel

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

640

Early Roman Water Mill

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

641

Early Norse Water Mill

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

642

Fourneyron’s Turbine

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

643

Hydropower Design

644

Terminology (Jargon)Head

Water must fall from a higher elevation to a lower one to release its stored energy.

The difference between these elevations (the water levels in the forebay and the tailbay) is called head

Dams: three categorieshigh-head (800 or more feet)medium-head (100 to 800 feet)low-head (less than 100 feet)

Power is proportional to the product of head­x­flow

http://www.wapa.gov/crsp/info/harhydro.htm

645

Scale of Hydropower Projects Large-hydro

More than 100 MW feeding into a large electricity grid Medium-hydro

15 - 100 MW usually feeding a grid Small-hydro

1 - 15 MW - usually feeding into a grid Mini-hydro

Above 100 kW, but below 1 MWEither stand alone schemes or more often feeding into the grid

Micro-hydro From 5kW up to 100 kW Usually provided power for a small community or rural industry in

remote areas away from the grid. Pico-hydro

From a few hundred watts up to 5kWRemote areas away from the grid.

www.itdg.org/docs/technical_information_service/micro_hydro_power.pdf

646

Types of Hydroelectric Installation

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

647

Meeting Peak DemandsHydroelectric plants:

Start easily and quickly and change power output rapidly

Complement large thermal plants (coal and nuclear), which are most efficient in serving base power loads.

Save millions of barrels of oil

648

Types of SystemsImpoundment

Hoover Dam, Grand CouleeDiversion or run-of-river systems

Niagara FallsMost significantly smaller

Pumped StorageTwo way flowPumped up to a storage reservoir and returned

to a lower elevation for power generationA mechanism for energy storage, not net energy

production

649

Conventional Impoundment Dam

http://www1.eere.energy.gov/windandhydro/hydro_plant_types.html

650

ExampleHoover Dam (US)

http://las-vegas.travelnice.com/dbi/hooverdam-225x300.jpg

651

Diversion (Run-of-River) Hydropower

652

ExampleDiversion Hydropower (Tazimina, Alaska)

http://www1.eere.energy.gov/windandhydro/hydro_plant_types.html

653

Micro Run-of-River Hydropower

http://www1.eere.energy.gov/windandhydro/hydro_plant_types.html

654

Micro Hydro Example

http://www.electrovent.com/#hydrofr

Used in remote locations in northern Canada

655

Pumped Storage Schematic

656

Pumped Storage System

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

657

Completed 1967Capacity – 324 MW

Two 162 MW unitsPurpose – energy storage

Water pumped uphill at nightLow usage – excess base load capacity

Water flows downhill during day/peak periodsHelps Xcel to meet surge demand

E.g., air conditioning demand on hot summer daysTypical efficiency of 70 – 85%

ExampleCabin Creek Pumped Hydro (Colorado)

658

Pumped Storage Power Spectrum

659

Turbine Design

Francis TurbineKaplan TurbinePelton TurbineTurgo TurbineNew Designs

660

Types of Hydropower Turbines

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

661

Classification of Hydro Turbines

Reaction TurbinesDerive power from pressure drop across turbineTotally immersed in waterAngular & linear motion converted to shaft powerPropeller, Francis, and Kaplan turbines

Impulse TurbinesConvert kinetic energy of water jet hitting bucketsNo pressure drop across turbinesPelton, Turgo, and crossflow turbines

662

Schematic of Francis Turbine

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

663

Francis Turbine Cross-Section

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

664

Small Francis Turbine & Generator

"Water Turbine," Wikipedia.com

665

Francis Turbine – Grand Coulee Dam

"Water Turbine," Wikipedia.com

666

Fixed-Pitch Propeller Turbine

"Water Turbine," Wikipedia.com

667

Kaplan Turbine Schematic

"Water Turbine," Wikipedia.com

668

Kaplan Turbine Cross Section

"Water Turbine," Wikipedia.com

669

Suspended­Power, Sheeler, 1939

670

Vertical Kaplan Turbine Setup

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

671

Horizontal Kaplan Turbine

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

672

Pelton Wheel Turbine

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

673

Turgo Turbine

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

674

Turbine Design Ranges

KaplanFrancisPeltonTurgo

2 < H < 40  10 < H < 350 50 < H < 1300 50 < H < 250

(H = head in meters)

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

675

Turbine Ranges of Application

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

676

Turbine Design Recommendations

Head Pressure

High Medium Low

Impulse PeltonTurgo

Multi-jet Pelton

CrossflowTurgo

Multi-jet Pelton

Crossflow

Reaction   FrancisPump-as-Turbine

PropellerKaplan

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

677

Fish Friendly Turbine Design

www.eere.energy.gov/windandhydro/hydro_rd.html

678

Hydro Power Calculations

679

Efficiency of Hydropower Plants

Hydropower is very efficientEfficiency = (electrical power delivered to the

“busbar”) ÷ (potential energy of head water)Typical losses are due to

Frictional drag and turbulence of flowFriction and magnetic losses in turbine &

generatorOverall efficiency ranges from 75-95%

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

680

Hydropower Calculations

P­=­power in kilowatts (kW)g­=­gravitational acceleration (9.81 m/s2) = turbo-generator efficiency (0<n<1)Q­= quantity of water flowing (m3/sec)H­= effective head (m)

HQP

HQgP

10

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

681

Example 1aConsider­a­mountain­stream­with­an­effective­head­of­25­meters­(m)­and­a­flow­rate­of­600­liters­(ℓ) per­minute.­How­much­power­could­a­hydro­plant­generate?­Assume­plant­efficiency­()­of­83%.­

H­=­25 mQ­=­600 ℓ/min × 1 m3/1000 ℓ × 1 min/60secQ­=­0.01 m3/sec

= 0.83

P­­10QH­=­10(0.83)(0.01)(25) = 2.075P­ 2.1 kW

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

682

Example 1bHow­much­energy­(E)­will­the­hydro­plant­generate­each­year?

E­= P×tE­= 2.1 kW­×­24 hrs/day × 365 days/yrE­= 18,396 kWh annually

About­how­many­people­will­this­energy­support­(assume­approximately­3,000­kWh­/­person)?

People = E÷3000 = 18396/3000 = 6.13About 6 people

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

683

Example 2Consider­a­second­site­with­an­effective­head­of­100­m­and­a­flow­rate­of­6,000­cubic­meters­per­second­(about­that­of­Niagara­Falls).­­Answer­the­same­questions.

P­­10QH­=­10(0.83)(6000)(100)P­ 4.98 million kW = 4.98 GW (gigawatts)

E­=­P×t­=­4.98GW­×­24 hrs/day × 365 days/yrE­= 43,625 GWh = 43.6 TWh (terrawatt hours)

People = E÷3000 = 43.6 TWh / 3,000 kWhPeople = 1.45 million people

(This assumes maximum power production 24x7)

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

684

Economics of Hydropower

685

Production Expense Comparison

Wisconsin Valley Improvement Company, http://www.wvic.com/hydro-facts.htm

686

Capital Costs of Several Hydro Plants

Note that these are for countries where costs are bound to be lower than for fully industrialized countries

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

687

Estimates for US Hydro Construction

Study of 2000 potential US hydro sitesPotential capacities from 1-1300 MWEstimated development costs

$2,000-4,000 per kWCivil engineering 65-75% of totalEnvironmental studies & licensing 15-25%Turbo-generator & control systems ~10%Ongoing costs add ~1-2% to project NPV (!)

Hall et­al.­(2003), Estimation­of­Economic­Parameters­of­US­Hydropower­Resources,­Idaho­National­Laboratoryhydropower.id.doe.gov/resourceassessment/­pdfs/project_report-final_with_disclaimer-3jul03.pdf ­

688

Costs of Increased US Hydro Capacity

Hall, Hydropower­Capacity­Increase­Opportunities­(presentation), Idaho National Laboratory, 10 May 2005www.epa.gov/cleanenergy/pdf/hall_may10.pdf

689

Costs of New US Capacity by Site

Hall, Hydropower­Capacity­Increase­Opportunities­(presentation), Idaho National Laboratory, 10 May 2005www.epa.gov/cleanenergy/pdf/hall_may10.pdf

690

High Upfront Capital Expenses5 MW hydro plant with 25 m low head

Construction cost of ~$20 millionNegligible ongoing costsAncillary benefits from dam

flood control, recreation, irrigation, etc.

50 MW combined-cycle gas turbine~$20 million purchase cost of equipmentSignificant ongoing fuel costs

Short-term pressures may favor fossil fuel energy production

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

691

Environmental Impacts

692

Impacts of Hydroelectric Dams

693

Ecological ImpactsLoss of forests, wildlife habitat, speciesDegradation of upstream catchment areas due to

inundation of reservoir areaRotting vegetation also emits greenhouse gasesLoss of aquatic biodiversity, fisheries, other

downstream servicesCumulative impacts on water quality, natural flooding Disrupt transfer of energy, sediment, nutrientsSedimentation reduces reservoir life, erodes turbines

Creation of new wetland habitat Fishing and recreational opportunities provided by new

reservoirs

694

Environmental and Social Issues Land use – inundation and displacement of people Impacts on natural hydrology

Increase evaporative lossesAltering river flows and natural flooding cyclesSedimentation/silting

Impacts on biodiversityAquatic ecology, fish, plants, mammals

Water chemistry changesMercury, nitrates, oxygenBacterial and viral infections

Tropics

Seismic Risks Structural dam failure risks

695

Hydropower – Pros and Cons

Positive NegativeEmissions-free, with virtually no CO2, NOX, SOX, hydrocarbons, or particulates

Frequently involves impoundment of large amounts of water with loss of habitat due to land inundation

Renewable resource with high conversion efficiency to electricity (80+%)

Variable output – dependent on rainfall and snowfall

Dispatchable with storage capacity Impacts on river flows and aquatic ecology, including fish migration and oxygen depletion

Usable for base load, peaking and pumped storage applications

Social impacts of displacing indigenous people

Scalable from 10 KW to 20,000 MW Health impacts in developing countries

Low operating and maintenance costs High initial capital costs

Long lifetimes Long lead time in construction of large projects

696

Three Gorges – Pros and Cons

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

697

Regulations and Policy

698

Energy Policy Act of 2005

Hydroelectric Incentives Production Tax Credit – 1.8 ¢/KWh

For generation capacity added to an existing facility (non-federally owned)

Adjusted annually for inflation10 year payout, $750,000 maximum/year per facility

A facility is defined as a single turbineExpires 2016

Efficiency Incentive10% of the cost of capital improvement

Efficiency hurdle - minimum 3% increase Maximum payout - $750,000 One payment per facility Maximum $10M/year Expires 2016

5.7 MW proposed through June 2006

699

World Commission on Dams Established in 1998

Mandates Review development effectiveness of large dams

and assess alternatives for water resources and energy development; and

Develop internationally acceptable criteria and guidelines for most aspects of design and operation of dams

Highly socially aware organizationConcern for indigenous and tribal peopleSeeks to maximize preexisting water and

energy systems before making new dams

700

Other Agencies InvolvedFERC – Federal Energy Regulatory Comm.

Ensures compliance with environmental law IWRM – Integrated Water & Rsrc Mgmt

“Social and economic development is inextricably linked to both water and energy. The key challenge for the 21st century is to expand access to both for a rapidly increasing human population, while simultaneously addressing the negative social and environmental impacts.” (IWRM)

701

Future of Hydropower

702

Hydro Development Capacity

hydropower.org

703

Developed Hydropower Capacity

World Atlas of Hydropower and Dams, 2002

704

Regional Hydropower Potential

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

705

Opportunities for US Hydropower

Hall, Hydropower­Capacity­Increase­Opportunities­(presentation), Idaho National Laboratory, 10 May 2005www.epa.gov/cleanenergy/pdf/hall_may10.pdf

706

Summary of Future of Hydropower

Untapped­U.S.­water­energy­resources­are­immense Water­energy­has­superior­attributes­compared­to­other­renewables: Nationwide­accessibility­to­resources­with­significant­power­potential Higher­availability­=­larger­capacity­factor Small­footprint­and­low­visual­impact­for­same­capacity

Water­energy­will­be­more­competitive­in­the­future­because­of: More­streamlined­licensing Higher­fuel­costs State­tax­incentives State­RPSs,­green­energy­mandates,­carbon­credits New­technologies­and­innovative­deployment­configurations

Significant­added­capacity­is­available­at­competitive­unit­costs Relicensing­bubble­in­2000-2015­will­offer­opportunities­for­capacity­increases,­but­also­some­decreases

Changing­hydropower’s­image­will­be­a­key­predictor­of­future­development­trends

Hall, Hydropower­Capacity­Increase­Opportunities­(presentation), Idaho National Laboratory, 10 May 2005www.epa.gov/cleanenergy/pdf/hall_may10.pdf

707

Next Week: Wind Energy

708

Extra Hydropower Slides

Included for your viewing pleasure

709

Hydrologic Cycle

710

World Hydropower

Boyle, Renewable­Energy,­2nd edition, Oxford University Press, 2003

711

Major Hydropower ProducersCanada, 341,312 GWh (66,954 MW installed) USA, 319,484 GWh (79,511 MW installed) Brazil, 285,603 GWh (57,517 MW installed) China, 204,300 GWh (65,000 MW installed) Russia, 173,500 GWh (44,700 MW installed) Norway, 121,824 GWh (27,528 MW installed) Japan, 84,500 GWh (27,229 MW installed) India, 82,237 GWh (22,083 MW installed) France, 77,500 GWh (25,335 MW installed)

1999 figures, including pumped-storage hydroelectricity

“Hydroelectricity,” Wikipedia.org

712

Types of Water Wheels

713

World Energy Sources

hydropower.org

714iea.org

OECD: most of Europe, Mexico, Japan, Korea, Turkey, New Zealand, UK, US

Evolution of Hydro Production

715iea.org

OECD: most of Europe, Mexico, Japan, Korea, Turkey, New Zealand, UK, US

Evolution of Hydro Production

716

Schematic of Impound Hydropower

717

Schematic of Impound Hydropower

718

Cruachan Pumped Storage (Scotland)

719

Francis Turbine – Grand Coulee

720

Historically…Pumped hydro was first used in Italy and

Switzerland in the 1890's. By 1933 reversible pump-turbines with motor-

generators were availableAdjustable speed machines now used to

improve efficiencyPumped hydro is available

at almost any scale with discharge times ranging from several hours to a few days.

Efficiency = 70 – 85%

http://www.electricitystorage.org/tech/technologies_technologies_pumpedhydro.htm

721

Small Horizontal Francis Turbine

722

Francis and Turgo Turbine Wheels

723

Turbine Application Ranges

Definition: Energy conservation means reduction in energy consumption but without making any sacrifice of quantity and quality of production.

Energy conservation can be defined as the substitution of energy with capital, labour, material and time.

04/13/2023724

Energy conservation and energy audit

Energy Conservation

04/13/2023Energy conservation and energy audit725

Principles Maximum thermodynamic efficiency in

energy use is termed as maximum work done production by using a given amount of primary energy input, as defined in the following form:

Maximum work = (Energy input) - (Energy loss in transfer) - (Energy discharge).

04/13/2023726

Energy conservation and energy audit

Energy Audit The energy audit would give a positive

orientation to the energy cost reduction, preventing maintenance and quality control programmes which are vital for production and utilies activities. Energy audit attempt. to balance total input of energy with its use.

Energy audit broadly covers the following questions:

(i)­How much energy are we consuming? (ii)­Where is the energy consumed? (iii)­How efficiently is the energy consumed? (iv)­Can there be improvements in energy

use?

04/13/2023727

Energy conservation and energy audit

Sankey diagram for energy audit

04/13/2023728

Energy conservation and energy audit

Benefits of Energy AuditBetter and most precise monitoring of

utility consumption points. Elimination of wastage. Reduction in operating costs. Increase in process output. Reduction in process equipment downtime. This will give an edge you strategic

business advantages in living up to global industries standards.

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types of energy audit:

Preliminary audit

Preliminary audit is carried out in the limited time i.e.­from 1 to 10 days and it highlights the energy cost and wastages in the major equipments and processes. It also gives the major energy supplies and demanding accounting

Detailed audit.

Detailed audit includes engineering recommendations and well defined projects with priorities. It accounts for the total energy utilized in plants. It involves detailed engineering for options to reduce cost/consumption. The duration for the visit would be l to 10 weeks.

04/13/2023Energy conservation and energy audit730

The action plan towards the achievement of energy conservation through energy audit may be drawn up into three phases:

(i) Short term: no capital investment or least investment to avoid energy wastages and minimizing non-essential energy users and improving the system efficiency through improved maintenance programme.

(ii) Medium term: Plan requires a little investment to achieve efficiency improvement through modifications of existing equipments and other operations

(iii) Long term: Plan is aimed to achieve economy through latest energy saving techniques and innovations. The capital investments are required to be studied thoroughly while finalizing the long term action-plan.

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Energy Conservation Approach/Technologies 1. Method of installation:

(a) Re-cycling, (b) Retro fitting, (c) New process

2. Method of Energy use: (a) Waste energy recovery, (b) Waste material usage, (e) Waste energy utilization, (d) Process efficiency improvement/co-generation.

3. Size of investments: (a) Administrative and information process to create awareness and

reduce individually controlled energy use. (b) Small incremental investments to recover wastage energy, alter

process flows and retrofit facilities for better utilization. (c) Major capital expenditure to re-design production process

overtime. 04/13/2023Energy conservation and energy audit734

(a) Special boilers and furnaces:

(i) Igni-fluid/fluidized bed boilers.

(ii) Flameless furnaces.

(iii) Fluidized bed type heat treatment furnaces.

(iv) High efficiency boilers (thermal efficiency higher than 75 per cent in case of coal-fired and 80 per cent in case of oil/gas fired boilers).

(v) Waste heat boiler design for gas turbine combined cycle station.

(b) Instrumentation and monitoring systems for monitoring energy flows:

(i) Automotive electrical load-monitoring systems.

(ii) Digital heat loss meters.

(iii) Micro-processor-based control systems.

(c) Waste heat recovery equipment and generation system:

(i) Economizers and feed water heaters.

(ii) Recuperators and air preheaters.

(iii) Back pressure turbines for co-generation.

(iv) Heat pumps.

(v) Vapour absorption refrigeration system.

(vi) Organic Rankine cycle power systems.

(d) Power factor-correcting devices: shunt capacitors and synchronous condenser & system

04/13/2023Energy conservation and energy audit735

Energy Saving Devices Eligible for higher Depreciation

Renewable energy devices eligible for higher depreciation(i) Flate plate solar collectors.

(ii) Concentration and pipe-type solar collectors.

(iii) Solar cookers.

(iv) Solar water heaters and systems.

(v) Air/gas/fluid heating systems.

(VI) Solar crop driers and & system

(vii) Solar refrigeration, cold storage and air conditioning sys tems.

(viii) Solar stills and desalination systems.

(ix) Solar-power generating systems.

(x) Solar pumps based on solar thermal and solar photo-voltaic conversion

(xi) Solar photo-voltaic modules and panes for water pumping and other applications.

(xii) Wind mills and any specially designed devices which run on wind mills.

(xiii) Any special devices including electric generators and pumps running on wind energy.

(xiv) Biogas plants and biogas engines.

(xv) Electrically operated vehicles including battery powered Or fuel cell powered vehicles.

(xvi) Agricultural and municipal waste conversion devices producing energy.

(xvii) Equipment for utilizing ocean waves and thermal energy.

(xviii) Machinery and plants used in the manufacture of any of the above items. 04/13/2023Energy conservation and energy audit736

Co-Generation In a cogeneration system, the mechanical

work is converted into electrical energy in an electric generator, and the discharged heat, which would otherwise be dispersed to the environ ment, is utilized in an industrial process or in other ways. The net result is an overall increase in the efficiency of fuel utilization.

04/13/2023Energy conservation and energy audit737

04/13/2023Energy conservation and energy audit738

efficiencygenerator steamη

efficiencyplant electricη

ΔHE

E

outputenergy totaloffraction electricale

η

e)(1

η

e

: isput out energy unit totalper addedheat the

steam, andy electricit of generation separateFor

plant toaddedHeat Q

steam processin energy heat or energy,Heat ΔΗ

generatedenergy electricE

Q

ΔHEη

h

e

s

he

A

s

A

sco

04/13/2023Energy conservation and energy audit739

hc

ee

)1(

1c

c

bygiven for thereis

generation separate

for η efficiency combined The

topping cycle

primary heat at the higher temperature end of the Ranking cycle is used to generate high-pressure and temperature steam and electricity in the usual manner. Depending on process requirements, process steam at low pressure and temperature is either

(a) extracted from turbine at an intermediate stage, such as for feed water heating, or

(b) taken at the turbine exhaust, in which case it is called a back­pressure­ turbine.­ Process steam pressure require ments vary

widely, between 0.5 and 40 bar.

bottoming cycle

primary heat is used at high temperature directly for process requirements.

04/13/2023Energy conservation and energy audit740

Types of Co-generation

In addition most process applications require low grade (temperature availability) steam. Such steam is conveniently produced in a topping cycle. Some are :

(a) Steam-electric power plant with a back pressure turbine: most suitable only when the electric demand is low compared with the heat demand.

(b) Steam-electric power plant with steam extraction from a condensing turbine: suitable over a wide range of ratios.

(c) Gas turbine power plant with a heat recovery boiler (using the gas turbine exhaust to generate steam).

(d) Combined steam-gas turbine power plant. The steam turbine is either of the back-pressure type : most suitable only, when the electric demand is high, about comparable to the heat demand or higher, though its range is wider with an extraction-condensing steam turbine than with back-pressure turbine.

(a) Or of the extraction-condensing type, (b) above. 04/13/2023Energy conservation and energy audit74

1

04/13/2023Energy conservation and energy audit742

150-220°C

04/13/2023Energy conservation and energy audit743

Combined cycle power generationThe combined cycle power generation

system has the following advantages over combined system;

(i) Higher efficiency. (ii) Low specific cost of the gas turbine. (iii) Smaller space requirement. (iv) Less cooling water demand.

04/13/2023Energy conservation and energy audit744

Waste Heat Utilization Various possibilities are being considered for making use of the

large amount of heat heat is dissipated to the environment by direct discharge of the

warmed water 50 to 65% of the heat is removed by the cooling water. heat discharged from the high temperature cycle can be used

to generate steam for a conventional turbine

Gas turbineDiesel enginePotassium vapour cycleThermionic conversionMagneto-hydro-dynamic conversion

04/13/2023Energy conservation and energy audit745

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The combined cycle power generation from coal two different routes may be considered. These are ;

(1) Combined cycle power generation through pressurized fluidized bed combustion of coal (PFBC).

(2) Integrated gasification combined cycle (lGCC) power generation

1. Combined cycle power generation through pressurized fluidized bed combustion of coal (PFBC)

The major advantages of pressurized fluidized bed combustion of coal are :

(i) Ability to use a wide range of fuels. specially high sulpbur, high ash coals.

(ii) Elimination of separate fuel desulphurization unit.

(iii) Low combustion temperature, restricting NOx formation.

(iv) Increased heat transfer coefficient.

(v) Reduce combustor size and number of fuel feed points com pared to atmospheric FBC with similar power levels.

(vi) Improved volumetric heat releases relative to atmospheric FBC.

(vii) Increased thermal efficiency in combined cycle operation.

The two basic systems used with PFBC are:

(a) Pressurized steam-cooled combustor.

(b) Pressurized air-cooled combustor. 04/13/2023Energy conservation and energy audit74

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(1) The efficiency of the combined cycle plant is better than a simple gas turbine or steam cycle.

(2) The capital cost of combined plant with supplementary firing is slightly higher than a simple gas turbine plant and much below those of a classical steam plant of the same power capacity.

(3) The combined plant is more suitable for rapid start and shutdown than a steam plant.

(4) The cooling water requirement of a combined cycle is much lower than a pure steam plant having the same output.

(5) The combined steam offers self-sustaining features if unfortunately, power station is shut down due to some fault, the gas turbine offers a way to start the station from the cold shut conditions. No outside power source is required. Gas turbine is always equipped with a diesel engine to start from cold.

(6) Many utilities are planning and installing simple gas turbine units which will later to be converted into combined cycle operation. This two phase development requires short installation time for peaking power plus the future capability for efficient operation for base load generation.

(7) The present trend to increase the thermal efficiency of gas turbine plant is to increase the turbine inlet temperature. Higher turbine inlet temperature reduces the heat rate, fuel cost and generation cost. The present combined cycle efficiency may reach 50% soon then better turbine material would be available.

(8) The environmental standards of many old fossil fuel plants are not acceptable and they are likely to be closed. These can be renovated by replacing the old boiler with a gas turbine unit and heat recovery boiler. With these modification exhaust emission can be reduced and thermal efficiency and generating capacity can be increased.

04/13/2023Energy conservation and energy audit752

Advantages of combined cycle power plants

Heat Recuperators Heat recuperators, or heat exchangers: which can abstract sensible heat from

one stream of flowing fluid and supply it to another stream.

Main uses of Heat Recuperators

1. To extract useful heat from waste hot liquids and gases. The heat is transferred to secondary fluids, which can then he used for either space heating or for the supply of hot water to kitchens and bathrooms.

2. To operate calorifiers, which are particularly widely used in the district heating field. Thermal energy is transferred from the circulating fluid, which has had to be closed with poisonous substances such as hydrazine, morpholine and caustic soda in order to protect mild steel pipes from corrosion. The heat is given off via heat exchangers to highly purified town water to enable it to be used for cooking and washing purposes.

3. In district and group heating practice, heat exchangers are used to provide indirect hot water supply to, for example, high building. This supply hot water may he at a pressure insufficient to enable it to service either the top floors of a tall building or one sited on top of a hill. In such cases it is advantageous to use water/water heat exchangers to transfer the heat to the secondary medium, which can then be pumped to the top by a separate system.

4. For normal heat transfer from steam heaters or flues to circulating air, in order to raise this air to the required working temperature.

5. For the operating of air-conditioning equipment, in which heat is being abstracted from room air by the refrigeration fluid or by chilled air.

6. For the supply of heating to swimming pools, where heat generated by either conventional heat sources or by solar batteries is transferred to the large volume of swimming pool water.

7. For heat recovery from exhaust air, flue gases and other sensible heat sources.

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Thermal conductivity Thermal conductivity

Material W/M°K Material W/M °K

at 20°C at 20°C

Aluminium 237 Water 1.964

Copper 166 Toluene 0.44

Iron 147 Petrol 0.47

Magne8ium 159 Glycerol 0.97

Silver 427 Oil 0.75

Zinc 115 Air

(no convection) 0.025

Thermal Conductivities of Various Solids and Liquids

Heat exchangers can be subdivided conveniently into three categories:

Liquid/liquid heat exchangers. Liquid/gas heat exchangers or gas/liquid heat

exchangers. Gas/gas heat exchangers.

The heat transferred is a product of the following three variables:

The area of interface between the two flowing liquids,

The U-value of the interface, and The temperature difference between the two

fluids. 04/13/2023Energy conservation and energy audit75

8

(W) J/s )tdA.U.(tdQ ch

04/13/2023Energy conservation and energy audit759

Co-current and counter-current heat exchangers

Heat Regenerators The exhaust heat is absorbed by a soled thermal storage

material. This heat is then given off, to the incoming fresh air supply. The classical method of using heat regeneration is used in the gas industry to make hydrogen.

04/13/2023Energy conservation and energy audit760

222 CO HOH CO

22 COO2

1 CO

04/13/2023Energy conservation and energy audit761

Schematic of a typical installation of a heat regenerator

04/13/2023Energy conservation and energy audit762

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Percentage Fuel Saved through Reheating of Combustion Air

04/13/2023Energy conservation and energy audit765

Regenerator Materials

04/13/2023Energy conservation and energy audit766

Cost of energy lost to compressed-air leaks

04/13/2023Energy conservation and energy audit767

The heat-regenerative adsorption unit with its two sub-systems:

A = adsorptive system, B = HX-fluid loop

04/13/2023Energy conservation and energy audit768

Typical Heat Recovery Installation

Different companies use different methods of constructing the slowly rotating thermal wheel. The main criteria of construction must be:

(i)­Strength and durability. (ii)­High thermal storage capacity. (iii)­Ease of heat transfer with a minimum of

pressure drop of exhaust gases and supply air. (iv)­Correct thermal resistance design depending

upon tempera ture of heat supply gas used. (v)­Corrosion resistance.

04/13/2023Energy conservation and energy audit769

04/13/2023Energy conservation and energy audit770

Heat PipesA heat pipe is a heat transfer mechanism

that can transport large quantities of heat with a very small difference in temperature between the hot and cold interfaces.

Heat pipes are extensively used in many modern computer systems.

04/13/2023Energy conservation and energy audit771

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Length (nominal) 1500mm /1800mmOuter tube diameter 58mmInner tube diameter 47mm

Glass thickness 1.6mm Thermal expansion 3.3x10-6 oC

Material Borosilicate Glass 3.3Absorptive Coating Graded Al-N/Al

Absorptance >92% (AM1.5)Emittance <8% (80oC)Vacuum P<5x10-3 Pa

Stagnation Temperature >200oCHeat Loss <0.8W/ ( m2oC )

Maximum Strength 0.8MPa

04/13/2023Energy conservation and energy audit773

 Axial Groove  Fine Fiber  Screen Mesh  Sintering

 Wicking Material

Conductivity 

Overcome Gravity 

Thermal Resistance

Stability Conductivit

y Lost 

Axial Groove Good  Poor  Low  Good  Average 

 Screen Mesh Average  Average  Average Average  Low 

Fine Fiber Poor Good High  Poor  Average 

Sintering (powder)

Average  Excellent  High  Average  High 

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Temperature Range ( °C)

Heat Pipe Working Fluid

Heat Pipe Vessel Material

Measured axial(8) heat

flux ( kW/cm2)

Measured surface(8) heat flux ( W/cm2)

-200 to -80 Liquid Nitrogen Stainless Steel 0.067 @ -163°C 1.01 @ -163°C

-70 to +60 Liquid AmmoniaNickel,

Aluminum, Stainless Steel

0.295 2.95

-45 to +120 MethanolCopper, Nickel, Stainless Steel

0.45 @ 100°C(x) 75.5 @ 100°C

+5 to +230 Water Copper, Nickel 0.67 @ 200°C 146@ 170°C

+190 to +550

Mercury* +0.02%

Magnesium +0.001%

Stainless Steel 25.1 @ 360°C* 181 @ 750°C

+400 to +800 Potassium*Nickel, Stainless

Steel5.6 @ 750°C 181 @ 750°C

+500 to +900 Sodium*Nickel, Stainless

Steel9.3 @ 850°C 224 @ 760°C

+900 to +1,500 Lithium*Niobium +1%

Zirconium2.0 @ 1250°C 207 @ 1250°C

1,500 + 2,000 Silver*Tantalum +5%

Tungsten4.1 413

Typical Operating Characteristics of Heat Pipes

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The rate of fluid flow is determined by the following factors : The­pressure­drop­caused­by­differences­in­pressure­between­the­evaporator­section­and­the­condensing­section.

Capillarity­is the main effect causing the fluid to flow from the condensing end to the evaporator end of the heat pipe.

The­gravitational­head­

The four heat transport heat pipe limitations can be simplified as follows;

Sonic­limit - The rate that vapor travels from heat pipe evaporator to condenser

Entrainment­limit - Friction between heat pipe working fluid and vapor that travel in opposite directions

Capillary­limit - The rate at which the heat pipe working fluid travels from heat pipe condenser to evaporator through the wick

Boiling­limit - The rate at which the heat pipe working fluid vaporizes from the added heat

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Nature of fluids to be used in a heat pipe: Fluids used in a heat pipe must:

Be chemically stable over long periods of time. Be easy to purify and degasify. Be reasonably cheap. Not react with the materials of construction of the heat pipe Boil at the approximate temperature of heat input and delivery

without requiring the heat pipe to be pressurized excessively as this would involve a considerable and disadvantageous increase in the thickness of tube walls.

Classification of Heat Pipes Multiple tube type capillary heat pipe Gravity-induced fluid flow heat pipe. Osmotic flow heat pipe. Electro-Osmotic heat pipes. Inverse Thermo-siphon. Heat Plates. Flexibility heat pipes. The rotating heat pipe.

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Reclamation or Recovery of flue gas heat.Thermal recovery units in an air conditioning

system Use in industrial plant. Use in public buildings. Indoor swimming pools.Industrial heat recovery Process to process heat transfer

Indirect heating and cooling systems Cooling electronic components. Supply of heat or cold to moulding machines. Improvement in running of engines.

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Applications of Heat Pipes

List of industrial processes from which heat can be abstracted in order to preheat air used for space heating in other areas:

Paint drying ovens, Curing ovens Spray dryers

Forging areas Boilers Rubber vulcanizing units

Textile ovens Plating processes

Desiccant dehumidifiers Bleaching ovens Brick kilns

Paper dryers Heat treatment areas Reverbatory furnaces

Vinyl ovens Casting plant Paint spray booths

Foundries Baking ovens Timber dryers

Waste steam exhaust Grinding areas

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Heat PumpsA heat pump is a vapour-compression type

refrigerator, consisting of an evaporator unit (where latent heat is taken up) and a condenser unit (where heat is discharged), with a mechanical compressor between them.

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The major parts of a heat pump include:

Compressor: This increases the pressure of the refrigerant so that it will accept the maximum amount of heat from the air.

Condenser: Coils that move heat to or from the outside air.

Evaporator: Coils that move heat to or from the air inside the home.

Air handler: Fan that blows the air into the ducts of the home. Components 1, 2, 3 and 4 are found in all standard air conditioners.

Reversing valve: Changes the heat pump from air conditioning to heating, and vice versa. This is not part of the thermostat.

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Air-source heat pump in cooling mode

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Air-source heat pump in heating mode

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Ground-source (geothermal) heat pump in cooling mode

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Ground-source (geothermal) heat pump in heating mode.

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A boiler/tower heat pump system

A geothermal heat pump system

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Applications of Heat Pumps

As a domestic heat pumps Industrial and commercial applications of

Heat Pump Industrial

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Put Step towards the

energy conservation…………….

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Conserve Energy…

Thank You