ECONOMICS OF BIOGAS PLANTS AND THEIR ROLE

IN SAVING THE ENVIRONMENT

• Biogas, its composition and uses

• Energy equivalence and Commonly used organic matter for biogas generation

• Overall scheme for anaerobic digestion of organic matter

• Nutrient Contents of Digested Slurry from biogas plant and FYM

• Types of biogas plants

• Role of Biogas plants in saving of environment

• Status of biogas development in India

• Economics of family size biogas plants

What is Biogas• A gas obtained due to anaerobic decomposition of

organic matter (cattle dung)

• It is a mixture of methane, carbon dioxide, hydrogen sulphide, water vapor, oxygen, nitrogen and hydrogen.

• Biogas has been known as swamp gas, sewer gas, fuel gas, marsh gas etc.

In India, it is more commonly known as ‘gobar’ gas.

• The digester in which the decomposition takes place is known as BIOGAS PLANT

Composition of Biogas

• Methane 50-70%

• Carbon dioxide 30-45%

• Hydrogen 0-1%

• Nitrogen 0-1%

• Water 0.1%

• Hydrogen sulphide 0-1%

• Oxygen 0-1%

Common Uses of biogas

• Cooking

• Lighting

• Power generation

• Engine running

Energy Equivalence of biogas

Use of 1m3 of biogas as fuel can save other sources of energy as:

• 0.52 litre of diesel• 0.62 litre of kerosene oil• 3.40 kg of wood• 12.30 kg of cow dung cakes• 0.43 kg of LPG• 1.46 kg of coal• 4.70 KW of electricity

Commonly used organic matter used for generation of biogas

• Cattle dung• Kitchen and dining hall waste• Vegetable market waste• Poultry dropping• Crop residue• Pig and horse excreta• Aquatic weeds such as water hyacinth• Agro industrial waste • Sewage Sludge

Comparative Biogas Production of Different Feed Stocks

S No Type of feed stock Gas Yield per Kg ( m3 )

Normal Feed availability per animal per day (Kg)

1 Cattle dung 0.036 10 to 15

2 Human excreta 0.07 0.5

3 Horse dung 0.045 10

4 Sheep dropping 0.042 1

5 Camel droppings 0.056 6

6 Piggery waste 0.08 2.25

7 Poultry droppings 0.062 0.18

Overall scheme for anaerobic digestion of organic matter

1st Phase- hydrolysis of complex organic materials, i.e.,carbohydrates,fats,proteins, nitrogen compounds,salts etc. into soluble organic compounds, i.e., sugars,fatty acids,amino acids etc.

2nd Phase- soluble organic compounds are reduced to simpler compounds, i.e., organic acids (acetic acid, propionic acid etc.) , simpler alcohols and acetone.

3rd Phase- Organic acids ,mainly acetic acid and certain other oxidised compounds are converted to methane and carbon dioxide by methanogenic bacteria.

(

and digested slurry

Nutrient Contents of Digested Slurry from biogas plant and FYM

S.No. Nutrient FYM Biogas slurry

Range % Average % Range % Average %

1. Nitrogen (N2) 0.5 to 1.0 0.8 1.4 to 1.8 1.6

2. Phosphorus

(P2O

5)

0.5 to 0.8 0.7 1.1 to 2.0 1.55

3. Potash (K20) 0.5 to 0.8 0.7 0.8 to 1.2 1.0

Source: Biogas Technology: A training manual for extension, FAO

TYPES OF BIOGAS PLANTS

• FLOATING DRUM TYPE

• FIXED DOME TYPE– JANTA BIOGAS PLANT– DEENBANDHU BIOGAS PLANTS

KVIC MODEL BIOGAS PLANT (Floating drum type)

JANTA BIOGAS PLANT (Fixed dome type)

Deenbandhu biogas plant

Modified Deenbandhu and Janta biogas plants

• The inlet in the traditional biogas plant is designed and modified by providing 12 inch dia pipe inclined at about 75 degrees with horizontal.

• The outlet is accordingly modified as per requirement

• The water requirement : 30 % of cattle dung as compared to 100 % of cattle dung in traditional biogas plants

• Digested Slurry is more thick hence easy to manage

Modified Janta biogas plant

• Inlet 30 cm diameter PVC pipe • Angle of inclination of pipe with horizontal=75o

DEMONSTRATION OF MODIFIED JANTA BIOGAS PLANT AT THE RESIDENCE OF SH. TARSEM SINGH, RURKI KHURD

DEMONSTRATION OF MODIFIED JANTA BIOGAS PLANT AT THE RESIDENCE OF MANJEET KAUR, BHARBHURGARH

DEMONSTRATION OF MODIFIED DEENBANDHU BIOGAS PLANT AT THE RESIDENCE OF LABH SINGH, BEEPUR

Role of Biogas plants in saving of environment

• Direct and immediate impact :– Save other fuels and hence less stress on other fuels

– Using biogas as a kitchen fuel can prevent deforestation and hence soil erosion

– Change of environment in the house as biogas is a clean fuel. Other fuels being commonly used creates pollution by generating smoke.

– The use of biogas prevents chances of eye diseases and respiratory diseases. Hence healthy life of rural woman.

– Clean kitchen and utensils and hence saving in the time of women

– Clean House and hence less expenditure for maintenance of house

Role of Biogas plants in saving of environment (contd)

• Reduction in green house gases:– How?

Green house gases• The gases which trap heat in the earth's atmosphere and

cause rise in temperature are known as green house gases.

– Greenhouse gases are the major cause of global warming.

Different green house gases • Naturally present green house gases in the atmosphere

– carbon dioxide, – methane– nitrous oxide– water vapor and– ozone

• Green house gases due to human activities– hydroflurocarbons (HFCs) – perfluorocarbons and – sulphur hexafluride.

Some activities responsible for green house gases

• Agriculture and industrialization

• Fossil fuel burning like that of coal in power plant leads to high emissions of carbon dioxide gas.

• Methane generated during Anaerobic decomposition of organic material

• Emission of nitrous oxides due to nitric acid production, use of cars with catalytic converters, the use of fertilizers in agriculture and the burning of organic matter

.

Kyoto Protocol for Control of green house Gas emission

• An international agreement signed (December 1997) by  about 180 countries with the aim to reduce green house gases emissions in order to save the environment

• Countries have been assigned maximum carbon emission levels and can participate in carbon credit trading.

Carbon Creditsystem and carbon trade

• The carbon credit and carbon trade system was ratified in conjunction with the Kyoto Protocol. Its goal is to stop the increase of green house gas emissions. 

For example, – if an environmentalist group plants enough trees to reduce emissions by

one ton, the group will be awarded a credit. – If a steel producer has an emissions quota of 10 tons, but is expecting to

produce 11 tons, it could purchase this carbon credit from the environmental group. 

– The carbon credit system looks to reduce emissions by having countries honor their emission quotas and offer incentives for being below them

Potential of methane wrt carbon dioxide as green house gas

• Green house gas methane is more than 20 times as powerful as carbon dioxide at entrapping heat in the atmosphere.

• Reaction during burning of methane (biogas).

• Hence one molecule of methane is converted into one molecule of carbon dioxide and as such the effect of methane will be reduced to 1/20th of its effect as compared to when it is released as such in the atmosphere.

HeatOHCOOCH 2224 22

Theoretical computation of carbon credit for 3 m3 biogas plant

• 1 m3 CO2 = 0.483 kg of carbon at about 30o C• 1 m3 of CH4 = (20-1)0.483 =9.18 kg of carbon

For a 3 m3 biogas plant• Estimated biogas generated per day= 3 m3

• Assuming 60 % methane in biogas• As such 3 m3 of biogas = 0.6*3 m3 of CH4 = 1.8 m3 of methane• 1.8 m3 of methane =1.8*9.18=16.52 kg of carbon/day • In one year = 365*16.52 =6030 kg of carbon=6 tonne of carbon• 1 tonne of carbon credit = 17 Euro• Equivalent credit earned in one year by 3 m3 biogas plant= 102

Euro• 1 Euro= Rs 59• 102 Euro = 6018 Rs• Thus a 3 m3 biogas plant can theoretically earn carbon credit

equivalent to Rs 6018 in one year.

Status of biogas development in India

• Total potential of biogas plants based on cattle dung in India: 1,23,39,300

• Biogas plants installed as on 31-12 2009 :41,85,442

• % of total potential exploited : 33.9

For Punjab

• % of total potential exploited for Punjab : 24.7

• % of total potential exploited for Punjab : 17.8

• Change for India in last 2.5 years : 2.8 %

• Change for Punjab in last 2.5 years :5%

S No

State/ Union Territories

Estimated Potential (Nos. of Biogas Plants)

Cumulative achievements* as on 31/12/2009

Percentage of Biogas Plants

installed against total

potential

1 Sikkim 7300 6926 94.9

2Maharashtra 897000

773410 86.2

3 Kerala 150000 124202 82.8

4 Mizoram 5000 3770 75.4

5 Gujarat 554000 404973 73.1

6 Karnataka 680000 411241 60.5

7 Nagaland 6700 3743 55.9

8 Goa 8000 3878 48.5

9 West Bengal 695000 305760 44.0

10

Andhra Pradesh

1065000

452499 42.5

11 Orissa 605000 235393 38.9

12

Arunachal Pradesh

7500

2818 37.6

13

Himachal Pradesh

125000

45488 36.4

14 Tamilnadu 615000 215033 35.0

15Meghalaya 24000

6058 25.2

16 Punjab 411000 101705 24.7

17 Assam 307000 74187 24.2

18Uttar

Pradesh1938000

419516 21.6

19

Madhya Pradesh

1491000

287549 19.3

20 Haryana 300000 53345 17.8

21 Bihar 733000 125688 17.1

22 Pondicherry 4300 573 13.3

23Uttarakhand 83000

9590 11.6

24

Tripura 28000

2771 9.9

25

Dadra & Nagar Haveli

2000

169 8.5

26 Chattisgarh 400000 30576 7.6

27 Rajasthan 915000 67172 7.3

28 Chandigarh 1400 97 6.9

29

A&N Islands

2200

137 6.2

30 Manipur 38000 2128 5.6

31 Delhi 12900 679 5.3

32 Jharkhand 100000 4408 4.4

33

Jammu & Kashmir

128000

2352 1.8

  Total 1,23,39,300   41,85,442 33.9

Economics of Family size Deenbandhu Biogas Plants

S.No. Item Capacity of Biogas Plants (m3)

3 4 5 6

1. Estimated cost (Rs.) 14000 15500 16500 18000

2. Equivalent Biogas produced per month in terms of LPG (Cylinders)

2.57 3.42 4.28 5.14

3. Monthly saving from Biogas in terms of LPG (Assumed cost of LPG cylinder =Rs.330/-)

771 1026 1284 1542

4. Approximate pay back period of Biogas Plant (years)

1.50 1.25 1.10 1.00

Estimated cost and Payback period for Deenbandhu biogas plants on the basis of saving of LPG

Economics of Family size Biogas Plants

• The initial cost of the plant can be recovered in a very short time due to savings in the use of alternate fuels.

• The user will be getting the biogas from the plants for more than 25 years.

• User is saved from the increase in cost of alternate fuels during the life of plant

• All the farmers rearing animals should adopt this technology as it requires one time investment and its benefits are derived for rest of the life of plant.

• Government of India provides an incentive of Rs. 8000/- or 50% of cost which ever is less for the installation of biogas plants.

Economics of Family size Biogas Plants (contd)

• An additional incentive of Rs 1000/- is provided for connecting the toilet to the biogas digester

• Attachment of toilet to the biogas plant will decrease the cost of toilet significantly as no separate septic tank will be required for the toilet.

• Value of the good manure and carbon credit earned has not been considered in computing the payback period.

• Keeping all the incentive into consideration the initial cost will be recovered in a very short time.

• There is no major maintenance cost for the plant and the operation of the plant is very simple.

Requirement of dung and number of

animals for different size of biogas plants Capacity of

biogas plant

(m3 )

Approximate

No. of

animals

required

Quantity of

fresh dung

required

(kg)

Cooking for

number of

persons

1 2-3 25 2-3

2 4-5 50 4-5

3 6-7 75 7-8

4 8-10 100 10-11

6 13-15 150 14-16

Alternate model of promoting Biogas programme

• Some farmers may feel difficulty in arranging the initial capital for installation of biogas plant

• For such farmers a programme may be framed in which the bank provides interest free loan to the farmers.

• The loss in to the bank is compensated from the incentives to be provided to the farmers.

• The direct incentive to the farmers may be reduced in such cases

Installment for 20000/- loan at different rates of interest

Rate of

Interest

Monthly Installment for 20000

loan(Rs)

Total Interest paid (Rs)

Period of Return (Months) Period of Return (Months)

36 48 60 36 48 60

8 643 497 411 2491 3363 4260

7 633.5 488 402 2170 2925 3700

0 571.5 425.5 339

0 0 0

Hence• The use of biogas plants reduces the green house effect

due to anaerobic decomposition of organic matter to a large extent and helps to save our environment.

• Attaching the toilet to the biogas plant will improve the sanitary condition in villages and help in reducing the cost of the toilet.

• The biogas plants are easily affordable and economically viable and must be installed at a rapid rate to achieve 100 % potential of biogas plants . The investment is one time and the benefits are derived for rest of the life of plant.