Biogas: Cooking gas that can be produced at home

With the price of cooking gas increasing frequently, we must remember the importance of the hope of biogas. Biogas is a gaseous mixture of about 60% methane, 40% carbon dioxide, and small amounts of nitrogen and hydrogen sulfide, obtained from anaerobic fermentation of manure by microorganisms. Cattle dung is a suitable raw material for making biogas in India. In the absence of organic matter such as cow dung, other organic wastes such as plantain, maize stalks, African moss etc. can also be used for biogas production. The water obtained when rubber milk solidifies into sheets is also suitable for biogas production. Biogas can be used not only for cooking but also for lighting, running motors and agricultural machinery.

One kilogram of green manure produces 0.04 cubic meter of biogas per day and 10 kg of cow dung per day. The size of the plant depends on the purpose for which the biogas is to be used. About 0.34 cubic meters of biogas per person per day for cooking purposes means a household of 5-6 members would require a 2 cubic meter capacity biogas plant and 50 kg of dung per day. 4-5 cows need to be fed to get this much dung daily.

Chemistry of Biogas Production

First Step :

Micro organisms break down complex polymer fibers into monomers.

 (CH2O)6 CH2O

Second step:

At this stage the monomers are converted into organic acids as a result of the action of microorganisms.

(CH2O)6 CH3COOH

Third step:

Microorganisms that live only in aerobic environments produce methane and carbon dioxide from carbonic acid.

CH3COOH   CH4+ CO2

Factors Affecting Biogas Production

Temperature

Biogas is produced at the highest rate at 35°C. If the temperature is below 15°C, biogas production will be greatly reduced.

Fill rate

The digester, which is the core part of the biogas plant, is filled with manure according to its capacity. Only 10 kg of cow dung should be filled per cubic meter of digester capacity.

Density of the solid

A 1:1 ratio of green manure and water is mixed inside the plant and the solids concentration of the manure water is 7-9 percent.

PH value

High biogas production occurs when the pH value inside the digester is between 7 and 8.

Advantages of Biogas

The dung of 4-5 cows can be used to produce biogas for the cooking needs of a family of 5-6 members. The nitrogen in the manure is completely destroyed when it is dried. But there is no reduction in the nutrients of the manure discharged after biogas production. It can be very effective if applied in the field. By being able to reduce the consumption of firewood, unnecessary deforestation can be avoided to some extent. Biogas for cooking is much easier to use than fuels that cause smoke and health problems (coal, firewood, dry dung, kerosene). Biogas can be produced on an increased scale and used not only for cooking but also for lighting lamps and running motors and agricultural machinery. Using biogas can reduce rural population's dependence on petroleum products. Apart from this, the eye diseases of the villagers are reduced. Cleanliness increases. The standard of living is rising. It acquires public health importance as it destroys dangerous pathogens, eggs and larvae of intestinal worms in manure. Adding to this is the fact that the technology behind a biogas plant can be operated by any common man