BIOGAS PLANT A FIT OPTION FOR RURAL ENERGY

SEMINAR REPORT

OMANAKUTTAN. M

REG NO 89010736

INTRODUCTION

Biogas is clean environment friendly fuel that can be

obtained by anaerobic digestion of animal residues

and domestic and farm wastes, abundantly available

in the countryside.

Biogas is an important renewable energy resource for

rural areas in India

Biogas generally comprise of 55-65 % methane, 35-

45 % carbon dioxide, 0.5-1.0 % hydrogen sulfide and

traces of water vapor.

Average calorific value of biogas is 20 MJ/m3 (4713

kcal/m3).

• Biogas like Liquefied Petroleum Gas (LPG) cannot be liquefied under normal temperature and pressure.

• Critical temperature required for liquefaction of methane is -82.1oC at 4.71MPa pressure, therefore use of biogas is limited nearby the biogas plant.

• An estimate indicates that India has a potential of generating 6.38 X 1010 m3 of biogas from 980 million tones of cattle dung produced annually.

• The heat value of this gas amounts to 1.3 X 1012 MJ. In addition, 350 million tones of manure would also produce along with biogas.

INTRODUCTION

POTENTIAL OF BIOGAS IN INDIA* Cattle population : 300 million* Farm families : 75 million* Own 4 or more cattle : 43 million

* Potential of setting up family size BGP : 12 million * Established till Dec 2009 : 4.1 million* Dung collection (55% efficiency) : 1575 million kg/day*Gas production : 39.85million cu.m.gas/day*Assuming 60% eff.equivalent to = 112695 million

K.cal/day = 12.37 million lit.of kerosene

= 14.54 million lit. of crude oil= 16.26 million Kg.of coal

= 23.94 million lit. of fire wood = 131.04 million kWh.of

electricity

ADVANTAGES OF BIOGAS

• Less labour than tree felling • Trees can be retained • Biogas is a quick, easily controlled fuel • No smoke or smell (unless there is a leak)

so reduced eye/respiratory irritation • Clean pots • Sludge is a better fertilizer than manure or

synthetic fertilizers (andis cheaper then manufactured products)

• Reduced pathogen transmission compared to untreated waste

GENERATION AND FUEL PROPERTIES OF BIO GAS

Biogas, a mixture containing 55-65 percent

methane 30-40 percent carbon dioxide and

the rest being impurities (H2,H2s and some

N2), can be produced from the decomposition

of animal, plant and human waste. It is clean

but slow burning gas and usually has a

calorific value between 5000 to 5500 Kcal/Kg

(20935 to 2328 KJ/Kg) or 38131 KJ/m3.

ANAEROBIC & AEROBIC DIGESTION

Aerobic and anaerobic fermentation can be used to

decompose organic matter. Normally aerobic

fermentation produces CO2, NH# and small

amount of other gases. Anaerobic fermentation

produces Co2, CH4, H2 and traces of other gases

along which a decomposed mass. In aerobic

digestion the residue is rich in C, N2, P, K and other

nutrients. In a biogas plant the main aim is to

generate methane and hence anaerobic digestion

is used.

FACTORS AFFECTING GENERATION OF BIOGAS PH or hydrogen concentration

Temperature Total solid content Loading rate Seeding Uniform feeding Carbon nitrogen ratio of the Input material Diameter to depth ratio Nutrients Mixing or stirring retention time or rate of feeding type of feed stocks toxicity pressure acid accumulation inside the digester

BIOGAS PRODUCTION PROCESS

Biogas production process (Anaerobic digestion) is a multiple-stage process in which some main stages are:

Chemical reactions involved in biogas production:

C6H12O6 → 3CO2 + 3CH4

CO2 + 4H2 > CH4 + 2H2O  CH3COOH  > CH4 + CO2

THE QUANTITY, RATE AND COMPOSITION OF BIOGAS GENERATED DEPENDS ON

– The nature and concentration of the substrate,

– Feed rate,

– pH value,

– Bacterial population,

– Temperature, and

– Chemical inducers.

BIOGAS PRODUCTION POTENTIAL FROM DIFFERENT WASTES

UTILIZATION OF BIOGAS

• Cooking: Biogas can be used in a specially designed burner for cooking purpose. A biogas plant of 2 cubic metres capacity is sufficient for providing cooking fuel needs of a family of about five persons.

• Lighting: Biogas is used in silk mantle lamps for lighting purpose. The requirement of gas for powering a 100 candle lamp (60 W) is 0.13 cubic metre per hour.

• Power Generation: Biogas can be used to operate a dual fuel engine to replace up to 80 % of diesel-oil. Diesel engines have been modified to run 100 per cent on biogas. Petrol and CNG engines can also be modified easily to use biogas.

• Transport Fuel: After removal of CO2, H2S and water vapor, biogas can be converted to natural gas quality for use in vehicles.

ENERGYCONSUMPTION PATTERN IN RURAL AREAS wood

Cooking dung, Biogas Agri.residue

Domestic kerose Lighting Lighting Kerosene

Electricity

Biogas

Water Pumping DieselElectricity

Agriculture Diesel

Agri.operations electricityAnimal

Human

Vehicle Diesel/ petrol

Transportation

Cart Animal

Electricity

Industries Cottage Ind. Coal

Diesel /Petrol

Bio mass / Biogas

Overview of commercially viable technologies

• Family size biogas plants (1 to 10 m3 ) – KVIC, Deenbandhu, Janta, Pragati, Flexi etc.

• Large scale biogas plants (10 to 140 m3) – KVIC

• Large scale plants above 1000 m3 – UASB, Modified UASB, BIMA Digester (suitable for industrial effluents, MSW, fruit and vegetable waste etc.)

Out let Pipe

In let Pipe

Digester

Drum

FLOATING DRUM TYPE BIOGAS

PLANT

Gas outletInlet

Outlet

Biogas Plant

20 m3/day Capacity Biogas Plant installed at IIT Delhi

Biogas Plant Designs

Floating Drum

Fixed Dome

Fixed Dome type family size Biogas plant

[1] Deenbandhu

[2] Modified for solid state * Water : (-) 3/4th * Space : (-) 3/4th

* Gas : (+) 30% * Operation easier * Cost almost same

1

2

An outline of fixed dome biogas plant

Detailed structural design of fixed dome biogas plant

Out let

In letGas Out let Dome

Digester

FIXED DOME TYPE BIOGAS PLANT

PRAGATI DESIGN BIOGAS PLANT

*

KVIC MODEL

*

JANATA BIOGAS PLANT

DEEN BANDU BIOGAS PLANT

BIOGAS PLANT BASED ON KITCHEN WASTE

BIOGAS PLANT BASED ON KITCHEN WASTE

The biogas plant has following components.

1.  A mixer/pulper (5 HP motor) for crushing the solid waste

2. Premix tanks (3)

3. Predigester tank

4. Solar heater for water heating

5. Main digestion tank (35 m3)

6. Manure pits (4)

7. Gas lamps for utilisation of the biogas generated in the plant

BIOGAS PLANT BASED ON KITCHEN WASTE

The waste generated in kitchen in the form of vegetable refuse, stale cooked and uncooked food, extracted tea powder, waste milk and milk products can all be processed in this plant. The waste is converted into slurry by mixing water (1:1) in this mixture. From the predigestor tank, the slurry enters the main tank where it undergoes mainly anaerobic degradation by a consortium of archaebacteria belonging to Methanococcus group. These bacteria are naturally present in the alimentary canal of ruminant animals (cattle). They produce mainly methane from the cellulosic materials in the slurry. The undigested lignocellulosic and hemicellulosic materials then are passed on to the settling tank. After about a month, high quality manure can be dug out from the settling tanks.

SELECTING SITE FOR A BIO GAS PLANT

DISTANCEThe distance between the plant and the site of gas

consumption should be less in order to achieve economy in pumping of gas and minimizing gas leakage.

OPEN SPACE The sunlight should fall on the plant, as temperature between

150-300 is essential for gas generation at good rate.

SEASONAL RUN OUTProper care has to be taken to prevent the interference of run

off water during monsoon. Interfering bunds may construct.

SELECTING SITE FOR A BIO GAS PLANT

DISTANCE FROM WELLS

The see page of fermented slurry may pollute the well

water. So a minimum of 15m should maintain from the

wells.

SPACE REQUIREMENTS

Sufficient space must be available for day-to-day

operation and maintenance.

AVAILIBILITY OF WATER

Plenty of water must be available to use 7% to 9% slurry.

CONTRIBUTION OF BIOGAS TECHNOLOGY TO RURAL AREAS

* Better and cheaper fuel for cooking, lighting and power generation.

* Produces good quality enriched manure to improve spoil fertility.

* Effective and convenient way for sanitary disposal of human excreata, improving the hygienic conditions.

* generate social benefits - reducing burden on forest, reduction in drudgery of women and children.

* As a smokeless domestic fuel it reduces the incidence of eye and lung diseases.

5 hp Engine

for 1.5 Hrs.

Cooking for 16 Person

Mantle lamp (100 C.P.) 25-28 Hrs.

Electricity (5 Unit)70-80 kg.wet Digested slurry Enriched manure

FIG : POSSIBLE APPLICATION OF BIOGAS

10 Cattle or 6 buffaloes or 8

bullocks

100 kg. Dung + water equal

4 cum gas/ day

Cooking: Typical0.45m3 (16cubic feet) per hour stove, popular dimension are: jet size 2.25mm dia,area of jet -3.98mm2 Flame past size:6.0mm dia,No. of pasts :20, total area of posts =565mm2 ratio of jet area to flame post area = 1:142 Length & Dia of gas mixing pipe = 20mm

ON- OFF Valve

Gas jetAir

Adjuster

Flame parts

Gas mixing pipe

Biogas flame

Venture Tube

ON - OFF Gas Lock

Gas Regulator

Clay Nozzle

Opening screw

Mantle

Glass Globe

INSIDE TYPE Lamp

Biogas Lamp for Lighting