The document discusses the purification and utilization of biogas, a clean and environmentally friendly fuel generated from the anaerobic digestion of organic waste. It highlights India’s biogas potential, methods for purifying biogas by removing impurities such as carbon dioxide and hydrogen sulfide, and compares its calorific value to other fuels. Additionally, it examines applications of biogas for cooking, lighting, and power generation, emphasizing its benefits in improving rural livelihoods and reducing greenhouse gas emissions.

1. BIOGAS PURIFICATION AND
UTILIZATION

2. BIOGAS
 Biogas is clean environment friendly fuel
 Anaerobic digestion of animal residues and
domestic and farm wastes
 Biogas generally comprise of 55-65 % methane, 35-
45 % carbon dioxide, 0.5-1.0 % hydrogen sulfide
and traces of water vapour
 Average calorific value of biogas is 20 MJ/m3 (4713
kcal/m3)

3.  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
 Estimate indicates that India generating 6.38 X 1010
m3 of biogas from 980 MT/y of cattle dung
 The heat value of this gas amounts to 1.3 X 1012 MJ
 About 350 million tonnes of manure also generated
BIOGAS

4. 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 : 39.85M m3gas/day
Assuming 60% eff. equivalent to : 112695 M K.cal/day
= 12.37 ML kerosene
= 14.54 ML crude oil
= 16.26 M Kg.of coal
= 23.94 ML fire wood
= 31.04 M kWh e

5. CALORIFIC VALUE
 18.7 to 26 MJ/ m3 or 4,800 - 6,900 kcal/m3
CALORIFIC VALUE WITHOUT CO2
 between 33.5 to35.3 MJ/ m3
EXPLOSION LIMIT
 5 to 14 % in air
REMOVAL OF CO2
 Scrubbing with lime water or ethanol amine solution
REMOVAL OF H2S
 Adsorption on a bed of iron sponge and wood shavings
AIR TO METHANE RATIO
 for complete combustion is 10 to 1 by volume
PRESSURE AND TEMPERATURE NEEDED TO LIQUEFY
 Biogas needs 500 psi, at –83oC & LPG Needs 160 psi, at
ambient temperature

6. REMOVAL OF IMPURITIES
• Required gas quality = function of application
• Purification methods
 Traditional: scrubbing, pressure swing adsorption,
cryogenics
 Gas membranes
Application H2S CO2 H2O Traces
Gas heater
(boiler) < 1000 ppm no no yes (e.g. siloxanes)
CHP < 1000 ppm no
avoid
condensation yes (e.g. siloxanes)
Vehicle fuel yes yes yes yes
Gas Grid yes yes yes yes

7. CARBON DIOXIDE REMOVAL
• Removing CO2 leads to
o Increased heating value
o Consistent gas quality similar to natural gas
• Removal options
o Absorption (scrubbing)
o Pressure swing
adsorption

8. HYDROGEN SULPHIDE REMOVAL
o combustion product of H2S is SO2, which makes the exhaust
gases very corrosive (sulphuric acid) and contaminates the
environment (acid rain)
o Adequate removal of hydrogen sulfide to below 10 ppm is
important to reduce engine maintain requirement
o H2S changes the red blood pigment; the blood turns brown to
olive in colour. The transport of oxygen is hindered. The person
suffocates internally
o The symptoms are irritation of the mucous membranes (including
the eyes), nausea, vomiting, difficulty in breathing, cyanosis
(discoloration of the skin), delirium and cramps, then respiratory
paralysis and cardiac arrest
o At higher concentrations immediate respiratory paralysis and
cardiac arrest are the only symptoms
o Even if a person survives poisoning, long term damage to the
central nervous system and to the heart may remain

9. CO2 Removal
 Carbon dioxide is soluble in water. Water scrubbing uses the higher
solubility of CO2 in water to separate the CO2 from biogas.
 This process is done under high pressure and removes H2S as well as CO2.
 The main disadvantage of this process is that it requires a large volume of
water that must be purified and recycled.
Polyethylene glycol scrubbing
 This process is similar to water scrubbing; however, it is more efficient.
 It also requires the regeneration of a large volume of polyethylene glycol.
Carbon molecular sieves
 The carbon molecular sieve method uses differential adsorption
characteristics to separate CH4 and CO2.
 This adsorption is carried out at high pressure and is also known as pressure
swing adsorption.
 For this process to be successful, H2S should be removed before the
adsorption process.

10. Membrane separation
There are two membrane separation techniques:
High pressure gas separation
Gas-liquid adsorption
The high pressure separation process selectively separates H2S and CO2
from CH4. Usually, this separation is performed in three stages and
produces 96 per cent pure CH4.
Gas liquid adsorption is a new development and uses microporous
hydrophobic membranes as an interface between gas and liquids. The CO2
and H2S dissolve while the methane (in the gas) is collected for use.
H2S Removal
Activated carbon
 Activated carbon impregnated with potassium iodide can catalytically
react with oxygen and H2S to form water and sulphur.
 The reaction is best achieved at 7 to 8 bar and 50 to 70°C. Activated
carbon beds also need regeneration or replacement when saturated.

11. Biological desulphurization
 Natural bacteria can convert H2S into elemental sulphur in the
presence of oxygen and iron.
 This can be done by introducing a small amount (two to five per cent)
of air into the head space of the digester.
 As a result, deposits of elemental sulphur will be formed in the
digester.
 Even though this situation will reduce the H2S level, it will not lower
it below that recommended for pipeline-quality gas.
 This process may be optimized by a more sophisticated design where
air is bubbled through the digester feed material.
 It is critical that the introduction of the air be carefully controlled to
avoid reducing the amount of biogas that is produced.

12. Iron/iron oxide reaction
 Hydrogen sulphide reacts readily with either iron oxide or iron
chloride to form insoluble iron sulphide.
 The reaction can be exploited by adding the iron chloride to the
digester feed material or passing the biogas through a bed of
iron oxide-containing material.
 The iron oxide comes in different forms such as rusty steel
wool, iron oxide pellets or wood pellets coated with iron oxide.
 The iron oxide media needs to be replaced periodically. The
regeneration process is highly exothermic and must be
controlled to avoid problems.
Scrubbing and membrane separation
 As discussed in the section on CO2 removal, the CO2 and H2S
can be scrubbed by water, polyethylene glycol solutions or
separated using the membrane technique.

13. QUANTITIES OF BIOGAS CONSUMED FOR
DIFFERENT APPLICATIONS
Uses Specifications Biogas consumed (m3)
Cooking 2” Burner
4” Burner
6” Burner
0.33
0.47
0.62
Per person Per day
for cooking 0.24 m3/day
Gas Lighting
mantle lamp 100 Candle Power 0.13 m3/h
Dual fuel Engine 60-70%
Replacement
0.50 m3/ bhp /h
Electricity 1kwh 0.75

14. UTILIZATION OF BIOGAS FOR FUEL, LIGHT,
MANURE AND MOTIVE POWER GENERATION
BIOGAS - Methane (CH4) = 55-70 %, Carbon dioxide (Co2) =30-45%, other
gases like Nitrogen, Hydrogen, Co, Oxygen, and H2S in small quantities
ALMOST - 20% lighter than air and has ignition temperature of 650-750oC
It’s calorific value 4700 kcal/ m3
POTENTIAL GAS PRODUCTION FROM DIFFERENT FEED STOCKS
Type of Dung Feedstock per
day(m3)
Gas yield
(m3/kg)
Normal manure
availability per
animal per
day(kg)
Cattle 0. 36 0.036 10
Buffalo 0.54 0.036 15
Pig 0.18 0.078 2.25
Chicken 0.011 0.062 0.18
Human 0.028 0.070 0.40

15. COMPARISON OF VARIOUS FUELS
Name of Fuel Calorific value Thermal To replace Useful heat
k cal/kg) Efficiency (%) 1m3 Biogas (k cal/kg)
Bio gas (m3) 4713 60 1 2770
Kerosene (l) 9600 50 0. 620 lit. 4800
Fire wood (kg) 4700 10 3. 474 kg 470
Cow dung cake (kg) 2090 10 12. 29 kg 209
Char coal (kg) 6930 28 1. 458 kg 2079
Soft cake( kg) 6292 28 1. 605 kg 1887
LPG (kg) 10882 60 0. 433 kg 6529
Furnace oil (l) 9041 75 0. 417 6780
Coal gas (m3) 4004 60 1.177 2400
Electricity 860 70 4. 698 602

17. 5 hp Engine
for 1.5 Hrs
Cooking for 16
Person
Mantle lamp (100 CP)
25-28 Hrs
Electricity (5 Unit)
70-80 kg.wet Digested
slurry Enriched manure
10 Cattle or 6
buffaloes or 8
bullocks
100 kg. Dung
+ water equal
4 m3 gas/
day
APPLICATIONS OF BIOGAS

18. ENERGYCONSUMPTION IN RURALAREAS
Domestic
Cooking
Lighting
Wood
Dung
Biogas
Agrl. residue
Kerosene lighting
Electricity
Agriculture
Water pumping
Agrl. operations
Diesel
Electricity
Biogas
Electricity
Diesel
Animal
Human

19. Transportation
Industries
Vehicle Diesel / Petrol
Cart Animal
Coal
Electricity
Cottage industries
Diesel/Petrol
Biogas

20. BIOGAS TECHNOLOGY TO RURALAREAS
 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 excreta
 Improving the hygienic conditions
 Generate social benefits - reducing burden on forest,
reduction in drudgery of women and children
 Smokeless domestic fuel - reduces the eye and lung
diseases

21.  The primary domestic uses of biogas are cooking and lighting.
Because biogas has different properties from other commonly used
gases, such as propane and butane, and is only available at low
pressures (4 - 10 cm water), stoves capable of burning biogas
efficiently must be specially designed
 To ensure that the flame does not "lift off," the ratio of the total area
of burner parts to the area of the injector orifice should be between
225 and 300:1,because flame speed factor is 11.1(low)
 Recent Indian designs have thermal efficiencies of around 60%
 In China the Beijing-4 design has a thermal efficiency of 59 - 62%,
depending on the pressure
 Lighting can be provided by means of a gas mantle, or by generating
electricity
 Highest lamp efficiencies require gas pressures of 40 cm, which are
only possible with fixed dome digesters

22. UTILIZATION OF BIOGAS

23. GENERATION OF POWER
DIESEL / PETROL SAVING (DUAL FUEL MODE)
Air Filter
Exhaust pipe
Biogas
Diesel fuel
Injector
Piston -
Linear set up

24. QUANTITY OF DIESEL SAVED BY RUNNING
A 5 HP DUAL FUEL ENGINE ON BIOGAS
Size of biogas
(m3 /day)
5 hp engine is
run twice a day
Quantity of
diesel
8 4 hour 3.6
15 6.5 hour 5.8
25 12 hour 10.8

26.  Biogas, have been used successfully in dual fuel diesel engines. Normally
the modifications are simple
 The engine is usually started with pure diesel fuel and the biogas
increased gradually until it comprises around 80% of the fuel intake
 If the gas supply is interrupted, normal operation can still proceed with up
to 100% diesel fuel. With 80% biogas, engine performance is good and
20% more horsepower is delivered than with diesel alone
 The normal thermal efficiency of these engines is 25-30% and they use
approximately 0.45 m3 of biogas per horsepower-hour. Converting this to
electricity, approximately 0.75 m3 of biogas is required per kilowatt hour
 A recent report describes a 9000 kw station operating on biogas from
night-soil digestion
 Due to the low thermal efficiency of these engines, a large fraction of the
biogas energy can be recovered from the cooling water and exhaust gases
 This energy can be used to heat the digester, or for space heating of
animal sheds, greenhouses and buildings

27. 3800 M3 BIOGAS PLANT - BELGIUM

28. DISTILLERY
EFFLUENT, BRAZIL
WASTE WATER FROM
OIL MILLS

29. 1 MW BIOGAS BASED POWER PLANT, ANDHRA

30. CASE STUDY -170 m3
BHITBUDRAK – SURAT,
Gujarat
• Size of Biogas Plant - 2x 85 m3/day
=170 m3/day
• No. of Beneficiaries - 50
• Cow dung -2 Tons/day
• A complex of 20 community toilets
• Gas utilization - Cooking-2 hrs
morning & 2 hrs evening(1.5
m3/family per day)
• Pipeline length up to 1km distance
• Pipe quality - HDPE, pressurize
system - 0.3 kg/cm2(Rs. 2.5 lacs cost)
• Gas charge - 150/month-family
• Power -15kw
• Cost - Rs 28.00 lakhs

31. • Haibowal Dairy Complex,
Ludhiana
• 1 mega watt (MW) cattle
dung-based power project
• 235 tonnes/day
• Total cost power -Rs 14 crore
• Capacity -13-14,000 units of
electricity /day
• Forty-seven tonnes of bio
manure /day
• Biomanure - Rs 250/tonne
CASE STUDY - II 1 MW SOLID STATE BIOGAS
PLANT- PUNJAB

32. BUSES AND OTHER HEAVY
VEHICLES WITH BIOGAS

33.  Biogas is used as an alternative transportation fuel in light and
heavy duty vehicles, can use the same existing technique for
fuelling compressed natural gas vehicles
 In many countries, biogas is viewed as an environmentally
attractive alternative to diesel and gasoline for operating buses and
other local transit vehicles
 The sound level generated by methane-powdered engines is
generally lower than that generated by diesel engines and the
exhaust emissions are lower than the emission from diesel engines
 Application of biogas in mobile engines requires compression to
high pressure gas (>3000 psi) and may be best applied in fleet
vehicles
 A refuelling station may be required to lower fuelling time and
provide adequate fuel storage
VEHICULAR USE

34.  Biogas, if compressed for use as an alternative transportation fuel in
light and heavy duty vehicles, can use the same existing technique for
fueling already being used for compressed natural gas vehicles
 In many countries, biogas is viewed as an environmentally attractive
alternative to diesel and gasoline for operating buses and other local
transit vehicles
 The sound level generated by methane-powdered engines is generally
lower than that generated by diesel engines and the exhaust fume
emissions are considered lower than the emission from diesel engines,
and the emission of nitrogen oxides is very low
 Compressed biogas is becoming widely used in Sweden, Switzerland,
and Germany. A biogas-powered train has been in service in Sweden
since 2005
 Biogas also powers automobiles and in 1974, a British documentary
film entitled Sweet as a Nut detailed the biogas production process from
pig manure, and how the biogas fueled a custom-adapted combustion
engine
 In 2007, an estimated 12,000 vehicles were being fueled with upgraded
biogas worldwide, mostly in Europe

35. BIOGAS ENRICHMENT AND BOTTLING
 Potential of biogas is not fully utilized and
commercialized
 For commercialization, its area of application may
widen; from cooking fuel to vehicle fuel
 For use as a vehicle fuel, it should be bottled like CNG
 Before bottling-enriched in methane content 55 % to
95 %; similar to CNG

36. REFINING AND COMPRESSION OF BIOGAS
 Purification is carried out to enrich biogas by scrubbing off the
unwanted components (CO2 and H2S)
 More energy per unit volume of compressed biogas and to get rid
of the corrosive effect of H2S
 Easiest, simplest and cheapest method pressurized water as an
absorbent liquid
 Plants linked with dairy (350 cattle or more), sewage treatment
plants are suitable for this work
 Biogas bottling may start new business venture in villages
 Employment and income generation for village people
 Biogas manure enhances the organic content of soil-increases
water holding capacity of soil

37. Biogas Digester
Single Stage Compressor
Gas Storage Pressure Vessel
Moisture Removal
Biogas (CH4 CO2)
Biogas Scrubber
Dissolved CO2 in
Water
Flow Meter
Pump
Water Tank
Gas Storage Pressure Vessel
Moisture Filters
Pressure Reducers
Three Stage Gas
Compressor
High Pressure Cylinders for
Storage of Enriched Gas
Water
Enriched Biogas
PROCESS FLOW CHART OF BIOGAS ENRICHMENT
AND COMPRESSION SYSTEM

38. BIOGAS ENRICHMENT AND BOTTLING
SYSTEM

39. BDTC
Cow dung/bio gas
collection from
Existing dairies
Biogas/compressed
Bio gas production
Carbon credit
Bio
gas
Vermi
pack
Vermicompost/
Vermiwash
Vermi
wash
Domestic cooking
Irrigation
purpose
Rural
transportation
Land quality
improvement
Seed quality
improvement
Clean air
Development
Curbing GHGs
Cow dung collection from
rural women of villages
CNG/
LPG
Biogas/
scrubbing/
cleaning unit
•Increased
income for
rural
women
•Better
health of
women &
children
•Women
empower
ment
•Low cost
production
Increased
income of
farmer
INTEGRATED BIOGAS - FERTILIZER PLANT

40. 40
 Methane (Green house gas) released from
three landfills of Delhi during 2008 : 74,000 tonnes
(Indian Express 29.01.2010)
 Effect of methane is higher than from : 21 times
CO2 by
 Percentage of methane in harmful
green house gas : 18%(approx.)
Annual CO2 Emission reduction from
1.5 lakh biogas plants : 70.5375 tonne
 Expected Annual CER from 1.50
lakh biogas plants : Rs.75 lakh
BIOGAS- FERTILIZER PLANTS: MOST POTENT
TOOL TO HANDLE METHANE- A GREEN HOUSE
GAS

41. BIOGAS-POWERED FUEL CELL SYSTEM
 The solid oxide fuel cells built by
Acumentrics have the distinct advantage of
being able to run on biogas (which delivers
the most energy per hectare of crops), natural
gas, propane, ethanol, diesel or biodiesel and
don't require hydrogen
 Acumentrics, which specializes in the
manufacturing of solid oxide fuel cell systems
(SOFC) for power applications, won the 2007
New England Innovation Award

42. ANAEROBIC DIGESTION - UTILIZATION

43. THANK YOU