“There is no alternate to energy but

certainly there is an alternate

energy”…….

Turning Wastesinto

Watts

Gas produced by the anaerobic digestion or fermentation of organic

matter under anaerobic conditions.

Biogas = CH4 + CO2 + H2S + N2 + H2 etc

Typical biogas composition:

Methane, CH4 : 55-70%

Carbon dioxide, CO2 : 25-40%

Nitrogen, N2 : 0-2 %

Hydrogen Sulphide, H2S : 0-3 %

Hydrogen, H2 : 0-2 %

Oxygen, O2 : 0-2 %

• pH-value : 6.5 to 7.5

• Due Point : < - 80° C

What is biogas?

Methanogenesis

Complex Organic Carbon

Monomers & Oligomers

Organic Acids

Acetate – H2 / CO2

CH4 + CO2

Hydrolysis

Acidogenesis

Acetogenesis

Anaerobic Digestion

COMPLEX

ORGANIC

MATTER

SIMPLE

ORGANICS

ACETATE

H2

/ CO2

METHANE and CARBON DIOXIDE

LOW ODOR EFFLUENT

LIQUEFACTION

PHASE

GASIFICATION

PHASE

ACIDOGENS METHANOGENS

WHERE DOES BIOGAS COME FROM?

• Vegetation - When vegetation decomposes, it

gives off methane gas

• Farm and ranch animals - cattle, chickens, pigs

• Sewage – The treatment of human waste in

anaerobic digesters produces methane

• Landfills

• Garbage produces methane as it decomposes

Electrical and/or

thermal energy

Biofertilizer

Organic

wastesAnaerobic digestion

Biogas

Solar energy

Biomethane production

Animal husbandry

Crop harvesting

Industrial processing

Human consumption

Photosynthesis

H2O

CO2

Biogas Cycle

Energy

crops

Natural gas

pipeline

Cleaning &

UpgradingEnergy crops

CO2

Potential wastes that can be used for

biogas power generation

Leather Industry Wastes

Abattoir Industry Wastes

Fruit/Food Processing Wastes

Pulp & Paper Industry Wastewater

Municipal Wastewater/Sewage

Vegetable Market Yard Wastes

Animal/Agro Residue

Major types of biogas plants in

India

1. Fixed dome type

2. Floating drum type

3. Bag type

Flexible balloon biogas plant

“BIOGAS TO POWER”……….WHY?

Power is in short supply. 78,000MW planned in 11th Plan.

1.25 lac villages and 56 % of household are non electrified-

Power is in big deficit.

Rural, decentralized and renewable power -A Priority.

Enactment of Electricity Act 2003 and Renewable policy

2005 in place.

Process industries need high quality and uninterrupted

power.

Any expansion /New downstream projects will require

additional, quality power.

Power generation/Cogeneration is becoming an important

revenue stream.

“BIOGAS TO POWER”……….WHY?

Successful reference plants available –reduced risk.

Elemental Sulphur as a high value biproduct from

Bioskrubber process , an added advantage.

CDM benefits – Generate more power, get more benefit

Therefore generating additional power from biogas now

makes good business sense.

Biogas application from “ Heat to Power ” A High Value Shift

Current utilization of biogas - mostly as heat value.

Biogas fired Gas Engines - for high value shift.

1 m3 of gas fired in engine can give 2 units of power .

High efficiency - Electrical 40.8%+17.5%+22.9% =81.2%

System configuration -Biogas+Scrubber+Gas engines

H2S in the biogas must be removed for gas engine

application.

Typical H2S in biogas is 3% to 5%.Should be brought

down to 250 ppm.

Electricity status in India

Break-up of Power

• Thermal Power Plants – 75%

• Hydro Electric Power Plants - 21%

• Nuclear Power Plants - 4%

• Installed wind power Generation – 9655 MW

• 30% to 40% of electrical power is lost in transmission and distribution

*(2008)

Contd…

• Per capita electricity consumption: 600 kWhr per year.

• 84% villages electrified, 44% of rural households

electrified. i.e. still a long way to go to achieve a dark

free India.

• Per capita power consumption – 612 KWH

• Annual power production – 680 billion KWH

Energy in India

Electricity Generation : 557.97 TWh

INSTALLED CAPACITY FROM RENEWABLE ENERGY

Source: Ministry of New and Renewable Energy

Power demand…

• India’s economy - high growth rate and growing energy demand. Currently a shortage ≈ 18% and power cuts are very frequent – affecting the industry and continuous production.

• The Government of India gives special incentives to encourage the use of renewable sources of energy.

• MNRE has set a goal of installing 10 percent of the additional power generation capacity in the country through grid connected renewable power by 2012.

• Power generation from biogas has been the least utilised opportunity in India so far.

Ways to produce power

from biogas…

1. Biogas used in duel fuel engine with 75% - 80

% replacement of diesel

2. Through 100% biogas engines

3. Through fuel cells – direct conversion of

biogas into electricity.

4. Through burning biogas in boiler steam

turbineelectricity

Facts need to keep in mind….

• Biogas can be burned and used as a heat source (produce hot air,

hot water or steam).

• Biogas can be used to operate an engine generator set that

produces electricity and if the waste heat is captured and used,

(Combined Heat & Power-CHP), plant efficiency improves.

• The monetary benefit occurs when the electricity generated is used

to replace electricity that’s normally bought at retail.

• A Combined Heat & Power (CHP) unit increases the cost of an

anaerobic digester system.

• You can store gas – but can’t store electricity.

Biogas into Electricity conversion

through Engines

Power generation from biogas…..

Contd….

General Process flow diagram….

In Internal Combustion engines…

1. Adequate removal of hydrogen sulfide to below 10ppm is important to reduce engine maintainrequirement.

2. Often more frequent changing of engine oil and testingfor oil sulfur content can increase engine componentlife.

3. Dual-fuel carburetor can be employed to start-up and

shut down the engine system effectively - removing

trace sulfide from the internal parts.

4. Waste heat may be used for digester heating, space

heating, hot water and or refrigeration.

Treatment of biogas…

Treatment includes removal of hydrogen sulfide, water,

mercaptans, carbon dioxide, trace organics, and

particulates.

Treatment of biogas is necessary to maintain the engine

in good condition

It reduces greenhouse gas emissions

Will enhance calorific value of biogas

Biogas can be injected into a natural gas pipeline. i.e.

can be used as a replacement for natural gas

How comes H2S?

• Concentration of hydrogen sulfide in the gas is a function of feedsubstrate and inorganic sulfate content.

• Wastes high in proteins containing sulfur based amino acids(methionine and cysteine) - significantly influence biogas hydrogensulfide levels.

(For instance, layer poultry waste containing feathers made ofkeratin may produce biogas sulfide levels up to 20,000 ppm).

• Sulfate present in the waste, either from an industrial source (eg.pulping of wood) or from seawater (marine aquiculture) will bereduced to sulfide by sulfate reducing bacteria.

SO--4 S--

• H2S – High toxic and corrosive in nature

• The burning of the gas releases sulfur dioxide which is also a corrosive and toxic gas.

Can H2S be removed from Biogas?

• Removal of H2S from Biogas is possible

• Physical Methods: Absorption in water, adsorption in

activated charcoal/peat

- Large quantity of scrubber, high cost, useful for low

conc.

• Chemical Methods: Alkali, Alkaloamine, ferric oxides,

Zinc salts

- High cost, chemical waste generation

• Biotechnological Methods : Biofilter,Bioscrubber

Biotrickling filter

- High efficiency, Lower investment costs, Lead to

savings on energy, Avoid catalysts, Avoid formation of

secondary contaminants.

Biomethane

• Biomethane – the gas obtained after removing the impurities in the

biogas, such as carbon dioxide and hydrogen sulfide (H2S).

Sr.NoBiomethane Methane

1. Limited supply Unlimited supply

2. Renewable Not renewable

3. Good for environment Not good for environment

4. Biomethane recovery,

use and production

generates "Greentags" or

a "Renewable Energy

Credit" for the owners.

Natural gas sold by the gas

company does NOT generate

these incentives and new

revenue streams.

Basic Concept: How biogas is

converted into electricity in engines

Biogas as fuel

To alternator

- Electromechanical device

- Convert mechanical energy

into AC electric energy

- also known as AC generators

- based on Faraday's law of

electromagnetic induction

Alternator

Also called as ‘Flexible-fuel engine’.

Two different fuels (Biogas 70-80 % and other fuel

(generally diesel)) mixed together – the resulting blend is

combusted.

Operation produces less complex-hydrocarbon pollution,

and the engines have fewer internal problems.

Compression ignition is used.

Biogas Power generation

through

dual-fuel Engine

7

• Also called as gas engines

• Both compression and spark ignition can be employed

• Carburetor is replaced by venturi system to introduce

gas into the air flow

• Maximum power output is lower than dual fuel engine

• Electrically efficiency is lower than duel fuel engine

• Will cause corrosion in mechanical parts

• Overall, the dual-fuel engine perform well and have great

potential for use on-farm energy utilization.

Power generation through 100% biogas engine

Genset??

• Known as Engine-generator set

• Combination of an electrical generator and an engine

(prime mover) mounted together - a single piece of self-

contained equipment.

• Located in proximity to the end-user rather than in a

central location

• Economic, easy, and safe to install even on the domestic

level

• Ranging from small to very large size

GE Jenbacher engine models

Type 2 – 250 – 330 kWe

Introduced 1976 – 30 years continuous development

8 cylinder

GE Jenbacher engine models

Type 3 – 500 – 1,100 kWe

Engine

Generator set:

Internal

combustion

engine with 135

kW 240 VAC

electrical

generator.

Caterpiller 3406

Advanced Reciprocating Engine System

• ARES: High efficiency, low emissions gas engine

• US DOE, Caterpillar, Cummins, Waukesha Engine

• Biogas to electricity efficiency: 42% now, target 50%

• (Conventional efficiency 30%)

• Reduces NOX by 90%

• Biogas Technology Group is able to provide modular

power generation units ranging from 300KW – 1MW,

using mostly Caterpillar or Perkins engines

Example of 1030kW & 300kW

Generators

What is CHP?

‘Combined Heat and Power (CHP) – is a highlyefficient and environmentally friendly technology forgenerating heat and power (usually electricity) on sitefrom a single fuel source usually gas.’

Power generation systems create large amounts of heat– when converting fuel into electricity. Avg. central utilitypower plant turns ≈ 60% of the energy content of theinput fuel into heat and wasted.

Typical Co-generation Efficiency- 30% conversion of biogas to electricity- 50% recovery of waste heat

Capturing these waste heat - increase energy efficiency,operating cost savings, and reduced air pollution andglobal warming.

How does CHP work?

The basic elements of a CHP plant:

1.A prime mover (gas engine)

2.Electrical generator driven by the engine

3.Heat exchangers recovering heat from the engine

• Jacket cooling water

• Lubricating oil

• Turbocharger intercooler

• Exhaust gases

4.System control panel

GE Jenbacher gas module

Heat recovery -

heat exchanger

EngineEngine control

panelGenerator

Process flow diagram of CPH in Genset

Typical CHP flow diagram

Gas input

Engine hot

water circuit

Se

co

nda

ry h

ea

t

exch

an

ge

r

Electrical output

Exhaust heat

exchanger

Building hot

water return

Building hot

water feed

Exhaust

Engine hot

water circuit

Biogas plants in India

• Potential -12 million family type biogas plants

• Achieved - 4.12 million family type biogas plants - 34% of the potential.

• Functionality of the biogas plants is about 95.80%

• Domestic biogas plants can supply few hours of electricity for domestic needs .i.e. More beneficial in rural areas.

• Electricity can simply be produced by using Biogas generators of few kW capacity.

*APITCO Survey

Power generation Potential in Distillery

Units

• 1 litre alcohol distilled 15 litre wastewater

• Anaerobic Digestion

1 litre wastewater 15 litre of biogas

Per litre of alcohol distilled 225 litre biogas

• No. of distilleries: Nearly 300

• Total alcohol production : 3.20 billion litres/year

• Wastewater : 45 billion litres/year

• Biogas production: 1200 million m3 biogas

• Electricity Generation: 1 M3 Biogas 2KWh

• Total electricity: 2.4 million MWh/year

.

Directory of Indian Distilleries, All India Distillers' Association.

TARGET DISTILLERIES

Biogas to Power project will benefit all Distilleries such as:

Those having high power consumption from the grid.

Those having other plants/offices in Group companies

buying high and expensive power from the grid.

Those attached to sugar factory having cogen unit and

selling power to the grid.

Those wanting to sell power to a Third party

Alternative: Biogas Engine

• Very few distilleries have gone for power generation using biogas engines although it can be an attractive alternative:– Significant savings can be achieved by supplying the

entire electricity demand of the facility from own source

– Additional revenue can be achieved by exporting the surplus power to the National Grid.

– Distilleries can earn additional revenue through the CDM mechanism

CDM in distilleries

• The Clean Development Mechanism (CDM),

under the Kyoto Protocol, has introduced the

possibility of earning CERs - Certified Emissions

Reductions, “Carbon Credits” through utilisation

of the biogas for power (electricity) generation.

Hypothetical case in distillery

Theoretical case study of electricity generation

using biogas engine in a typical distillery:

1. CDM project development • CER revenue options

2. Power generation example, considering two

scenarios:• Case 1 – Selling the electricity to the grid and royalty to the client

• Case 1 – Selling the electricity to the Client; Savings for the Client

Process flow diagram with CDM and power

generation

Distillery35 KLPD

Raw materials

Power

Steam

A.D.

Facility

Raw

Spent

Wash

Alcohol 35 KL

Bio

composting

Press mud

Compost

for sale

1 MW Power

generation

package Boiler

Furnace

Oil

power

966 KW

Option 2

Biogas

Bagasse

Option 1

(to Grid)

Treated

Spent

Wash

Hypothetical Process Flow diagram before

CDM

Distillery35 KLPD

Raw materials

Power

Steam

Open

lagoon

Raw Spent Wash

Alcohol

BoilerFurnace Oil

Puente Hills 50 Megawatt Boiler run by Biogas, Los Angeles

in U.S

.

A waste-to-energy power plant located in Westchester

County, U.S.A

58 megawatt Waste-to-Energy power plant – biogas obtained from

wastes, expanded in 2007, Florida, US

Sandon Dock waste water treatment works, Liverpool

*CHP for digester heating water

Shakarganj Mills Ltd , Pakistan5 fully mixed digesters (CSTR) tanks

(each above 12,000 m3), gas holder and control room

Jack’s Gulley MBT plant, New South Wales, Australia

A Major Boost for Promotion of the

Renewable Energy Sector in India

“Electricity Act 2003'' notified on 10th June, 2003 - The most important

legislative development - encouraged the recent growth in renewable

power

Important features of this Act w.r.t. renewable energy:

It identifies the role of renewable energy technologies for supplying

power to the utility grid as well as in stand-alone systems.

The Act provides for the Independent Power Producers (IPP) to set

up renewable power plants for captive use, third party sale, power

trading and distribution.

It empowers the State Electricity Regulatory Commissions (SERCs)

to promote renewable energy and specify, for purchase of

electricity from renewable energy sources, a percentage of the

total consumption of electricity in the area of a distribution licensee.

Sample of Basic data for power generation

Parameter Unit Data

Distillery Operational Data

Distillery capacity KL/day 35

Spent wash generation m3/day 438

Inlet COD mg/L 110000

Biogas generation m3/hr 587

Methane content % 60

H2S content after H2S scrubber ppm < 300

Methane quantity fed to biogas engine m3/hr 352

Methane quantity fed to biogas engine m3/day 8446

Basic evaluation data

Power consumption

Present in house power consumption KWH/d 500

Present power consumption pattern through out the day uniform

hours/year for power consumption (270 days/year) hrs/year 6480

Present in house power consumption/yr KWH/yr 3240000

Power generation through biogas engine

Biogas engine rated power generation KW 1136

Biogas specific power generation for the biogas engine

@ 65% methane

KWH/m3 1.94

Auxiliary power for the biogas engine (85% efficiency) KWH 170

Net power generation KWH 966

Yearly power generation for say 6000 hrs KWH/yr 5,793,600

Engine sizing for biogas

• Engine has fixed energy input

– Rated electrical & thermal output

– Electrical efficiency

Points to ponder before engine selection:

1. Assess feedstock to digesters

– Food waste, energy crops?

2. Estimate biogas CH4 content

3. Estimate biogas volume

4. Determine biogas energy content (kW)

5. Select appropriate engine

“……the time is running out…soon,

there will be nothing left to burn on

earth but earth itself…”

BENEFITS OF RENEWABLE ENERGY

Avoid the high costs involved in transmission capex.

Avoid distribution losses – Technical & otherwise

Avoid recurring fuel cost

Boost the rural economy

Encourage self help groups & self dependence

Enable village co-operatives to supply and / or monitor

distribution

Make available much needed energy for basic needs at

the doorstep at affordable prices.

Potential of urban wastes in India

1. About 50 million tonnes of solid waste (1.48 lakh tonnes

per day) and 6000 million m3 of liquid waste are

generated every year by our urban population.

2. This translates into a potential for generation of over

2600 MW of power from urban wastes.

3. Generating substantial decentralized energy besides

reducing the quantity of waste for its safe disposal.

4. Requires 1750 acres of land for land filling/year.

*MNRE 2008-2009 Annual report

The major benefits of recovery of energy

from urban wastes are:

• Reduction in the quantity of waste by 60 % to

90%.

• Reduction in demand for land as well as cost for

transportation of wastes to far-away landfill sites.

• Net reduction in environmental pollution, and

generation of substantial quantity of energy.

Contd..In case of projects for generation of only biogas for thermal

application, the financial assistance is limited to Rs.1.0

crore/MWeq (i.e. biogas production of 12000 cu.m/day).

The Central Financial Assistance (CFA) in the range of

Rs.40,000 to Rs.30,000 per kW is available for

implementation of the programme by State Nodal Agencies

through village level organizations, institutions and private

entrepreneurs in rural areas for sale of electricity to individual/

community/grid etc.

Capital subsidy on re-imbursement basis is provided for

projects ranging from Rs.50 lakh to Rs.100 lakh per MW,

depending upon the systems, configuration and type of

project.

The Scheme is open to private and public sector enterprises

and organizations, as well as NGOs.

Potential from Industrial wastes

• India’s rapid industrialization has resulted in the generation of huge

quantity of wastes, both solid and liquid.

• Industrial sectors such as

-sugar, pulp and paper, fruit and food processing,

-sago/starch, distilleries, dairies, tanneries,

-slaughterhouses, poultries, etc.

• The potential for recovery of energy from industrial wastes is

estimated at about 1300 MW.

* MNRE annual report 2008-09.

Installed projects on Biogas power

generation in India

A total of 48 projects with aggregate

capacity of about 69.62 MWeq have been

installed in distilleries, pulp and paper

mills, slaughter houses, tanneries, starch

industries, sea-food processing, poultry

and oil extraction industries.

* MNRE annual report 2008-09.

Industrial waste-to energy projects…

Projects under Installation:

(i) A 6 MW power project in Andhra Pradesh based on poultry litter;

(ii) Two projects of 1 MW capacity each in Andhra Pradesh based on biogas;

(iii) A 5MW project in Maharashtra based on biogas from distillery effulents.

(iv) A “National Working Group” for the development of Biogas based power projects in distilleries aimed at installation of 500 MW capacity projects in distilleries by the year 2012

MNRE’s Financial assistance for projects of

various types :Setting up five pilot projects on energy recovery from Municipal Solid Wastes:

Rs.2 crore per MW, subject to ceiling of 20% of project cost and Rs.10.00 crore

per project, whichever is less, is provided for five pilot projects.

Power from biogas generated at Sewage Treatment Plants: 40% of the project

cost subject to a maximum of Rs.2.0 crore/MW for projects

Power generation from other Urban Wastes and mix of Urban and Agricultural /

Agro industrial Wastes: 50% of project cost subject to a limit of Rs.3 crore per

MW for projects.

Biomethanation technology for power generation from a mix of cattle dung,

vegetable market and slaughterhouse wastes along with agricultural residues

and agro-industrial wastes: Financial assistance of 30% of project cost subject

to upper limit of Rs.3.0 crore/MW is provided for projects.

Contd…

• In Jan 2006, the Ministry launched a programme on biogas based distributed/grid power generation of unit capacity from 3 kW to 250 kW.

• The Central Financial Assistance (CFA) in the range of Rs.40,000 to Rs.30,000 per kW is available for implementation of the programme by State Nodal Agencies through village level organizations, institutions and private entrepreneurs in rural areas for sale of electricity to individual/ community/grid etc.

Few installations in industries …1

PROJECT SECTOR Type Of

Gas

FLOW

M3/hr

H2S

In

%

H2S

Out

ppm

POWER

Equivalent MW

Kanoria Chemicals & Ind. Ltd.,

Ankleshwar, Gujrat

Distillery Biogas 875 2.0 500 2.0

SOM Distilleries,

Bhopal, M. P.

Distillery Biogas 1250 3.0 500 2.7

BMSS Ltd.,

Shripur, Dist. Solapur,(Maharashtra)

Distillery Biogas 500 3.0 1000 1.0

Degremont India Ltd.

For Delhi Jal Nigam Delhi. At Rithala

Sewage

Treatment

Plant

Biogas 840 1.0 1000 2.0

India Glycols Ltd

Kashipur, Uttranchal

Distillery

& Allied

Chemicals

Biogas 800 4.6 0.1 1.8

VA Tech Wabag Ltd..

For Chennai Metro-Perungudi

Sewage

Treatment

Plant

Biogas 381 1.0 630 0.60

VA Tech Wabag Ltd.

For Chennai Metro-Kodungaiyur

Sewage

Treatment

Plant

Biogas 521 1.0 630 1.0

Contd..

PROJECT SECTOR Type Of

Gas

FLOW

M3/hr

H2S

In

%

H2S

Out

ppm

POWER

Equivalent

MW

MMS Steel & Power Pvt. Ltd

Narimanan ,T.N.

Power

Plant

Natural

Gas

3333 0.08 10 10.0

MMS Steel & Power Pvt. Ltd

Kovilkallapal, T.N.

Power

Plant

Natural

Gas

1666 0.08 10 5.00

Luna Chemicals Ltd.

Asnad, Gujrat

Power

Plant

Biogas 650 3.5 500 1.30

Riddhi Siddhi Gluco Biols Ltd.

Gokak, Karnataka

Starch

Plant

Biogas 1200 2.0 500 2.0

Trichy Distilleries & Chem. Ltd.

Trichy, T. N.

Distillery Biogas 750 5.0 500 1.4

1.89 MW Power Generation Project Based on Biogas Produced from Starch

Industry Liquid Waste Through 100% Biogas

Engines by Riddhi Siddhi Gluco Biols Ltd., Golak, Belgaum Dist, Karnataka

Kanoria Chemicals Ltd.Ankleshwar, Gujarat

8.25MW biogas based power project in a distillery at Banur, Dist.

Patiala, Punjab

Brihan Maharashtra Sugar Syndicate Ltd.Akluj ,Maharashtra

A 30 tonnes/day capacity Biomethanation Plant for Power Generation

in Koyambedu Vegetable Market, Chennai

A 5500 M3 biogas plant for power generation using starch

industry waste at Phagwara, Punjab

A 1 MW Biogas Plant using distillery effluents installed at a

Sugar Mill in West Godavari District, A.P.

2.5 MW poultry litter based power generation project under

construction at Namakkal, Tamil Nadu

Biogas based power generation project (1x20kW and 1x40 kW) setup at a Dairy Farm in

Dist. Satna,

Madhya Pradesh

INDIA LYCOLS Ltd.Kashipur,Uttaranchal

INDIA GLYCOLS Ltd.Kashipur,Uttaranchal

8.25 MW biogas based Cogeneration power plant by M/s Chandigarh

Distillers and Bottlers Ltd., Banur, Distt. Patiala, Punjab

3 MW power generation project based on palm oil Industry Waste by

Sai Renewable Pvt. Ltd, West Godavari District, A.P

A biomethanation plant of 0.15 MW based on vegetable market and

slaughter house wastes for generation of power at Vijayawada, A.P.

5 MW power and 75 tonnes per day biofertiliser from Municipal Solid

Waste of Lucknow city, by M/s Asia Bioenergy India Ltd., Chennai

25 KWe Bio-methanation project based on leather solid waste (chrome

shavings) at M/s. Tata International Ltd., Dewas, M.P.

0.2 MW power generation project utilizing Sago industry liquid waste at

Ms. Varalakshmi Company, Salem, Tamil Nadu

Biogas power generation by steam turbine

• Utilise the biogas for power generation by burning as

supplemental fuel in the boiler.

• High pressure steam produced is used to generate

power using a steam turbine.

Biogas Power Generation through boiler

Cooling tower

Turbine

Generator

TransformerBoiler

biogas

What does

each part do?

The boiler is where the biogas is burnt to boil water

The steam from the boiler is used to turn a turbine

The turbine is connected to the generator, which acts like a dynamo – it generates electricity out of movement

The steam is cooled down and turned back into water in the cooling tower

Biogas power generation

through fuel cells

Basic principles of fuel cell (FC)

•Related to battery: both convert chemical energy into electricity

•Battery: the chemical energy has to be stored beforehand

•FC only operates when it is supplied from external sources

•Fundamental mechanism: inverse water hydrolysis reaction

Anode: 2H2

® 4H ++ 4e -

Cathode:

4e - + 4H + + O2

® 2H2O

Net reaction:

2H2 + O2 2H2O

• A fuel cell is an electrochemical conversion device

• It produces electricity from fuel (on the anode side)

and an oxidant (on the cathode side), which react in

the presence of an electrolyte.

• The reactants flow into the cell, and the reaction

products flow out of it, while the electrolyte remains

within it.

• Stationary equipment for power generation

• Generating Fuel cells can operate virtually continuously as long as the necessary flows are maintained

Biogas power generation through fuel cells

Contd..

• They consume reactant from an external source, which

must be replenished – a thermodynamically open system.

• By contrast, batteries store electrical energy chemically

and hence represent a thermodynamically closed system.

• Many combinations of fuels and oxidants are possible.

• A hydrogen fuel cell uses hydrogen as its fuel and oxygen (usually from air) as its oxidant.

• Other fuels include hydrocarbons and alcohols. Other

oxidants include chlorine and chlorine dioxide.

Working of Fuel cell

Technical Feasibility of Biogas Fuelled

Fuel Cells

• Numerous demonstrations have already proven the technical feasibility

– phosphoric acid fuel cell (PAFC) – Low Temperature

– molten carbonate fuel cell (MCFC) – High Temperature

– solid oxide fuel cell (SOFC) – High Temperature

• Most technical problems have been overcome

– wide array of contaminants to clean up

– high degree of variability in fuel quality

PAFC Demonstrations

• UTC Fuel Cells PC-25 currently in

operation

200-kilowatt PC25 that

converts anaerobic digester

gas generated by the

wastewater treatment facility

into usable heat and

electricity for the facility.

MCFC System on

Wastewater Treatment BioGas

1 Megawatt

Fuel Cells

Solid Oxide Fuel Cell powered by biogas, Finland

New York City WWTP Fuel

Cell Systems

Technical Challenges

Gas Clean Up• Contaminant removal requirements are highly dependent

on type of fuel cell used and the type of biomass. H2S,

organic acids, siloxanes, alkali metals, halogens.

• PAFC clean up system has been successfully

demonstrated and a performance verification report

published.

• PAFC more sensitive to poisons than SOFC and MCFC

• Siloxanes are a more serious problem!

• In high temperature fuel cells siloxanes form glassy

deposits

• Moisture removal

– Need dry gas

Gas Clean Up – Siloxane Removal

• Siloxane removal is one of the more

challenging aspects of using landfill or AD

biogas

• Agricultural waste ADG does not contain

siloxanes

– cows don’t use cosmetics and conditioner!!

Economic Feasibility

• The economics of biogas fuelled fuel-cell systems are stillvery difficult to assess. Even for PAFC systems that havehad a long operating history the predicted cost per kW andthe actual cost per kW can differ by a factor of two orthree.

• The cost of the fuel cell is also very vague.

• Based on material costs SOFC stacks look verycompetitive

– near term projected cost = US$400 per kW

– the potential cost reduction with large-volumemanufacturing methods is as low as US$180 per kW.

Biogas

Fuel Processing

• A fuel processor changes - composition of the

biogas - can be fed to a fuel cell system to a

hydrogen-rich mixture that can be fed to a

fuel cell

• The process adds complexity to the system

but usually is necessary in order to obtain

acceptable fuel cell performance and lifetime.

Conclusions

1. Biogas-fuelled fuel cell systems are technicallyfeasible and can operate for extended periods withgood reliability and performance

2. Economic feasibility is much more difficult toassess but it appears that costs are too high

- The impact of carbon credits on the economicsof biomass fuelled fuel cell systems may be asignificant factor in the near future.

3. Utilising waste biomass for power generation willnot solve our energy and GHG problems but it cansignificantly reduce GHG emissions

Sr.No Fuel cell system Engine Generator System

1. Cost per kilowatt is very high. Cost per kilowatt is low.

2. The biogas must be cleaned up to

strict specifications. Adds cost and

complexity while consuming energy.

The biogas can be used directly from the

digester with no cleanup.

3. The fuel cell is an emerging

technology.

It is a mature technology.

4. The greenhouse emissions and

particulates are very low

The greenhouse emissions of carbon

dioxide, sulfur dioxide carbon monoxide

and particulates are significant.

5. The fuel cell technology is

continuously improving at a rapid

rate.

The technology is mature and changing

slowly

6. The system is very quiet. The noise level is very high and sound

mitigation is necessary

7. There are few moving parts. There are many moving parts, most

moving in a hot environment needing oil

and cooling

Usable fuel

Useful by-products from the biogas process

Reduces Greenhouse Gas emissions

Sustainable Resource as long as we have wastes

Could fulfill the gap in the peak electricity demand and

supply

Highly possible in community and institutional biogas

plants

Advantages of biogas

based

power generation

So, in a word…A plethora of renewable energy is all around us, with even more ways

to make use of it.

The Three Rs of Recycling

Plus One!Reduce

Recycle Reu

seRECOVER