To reduce emissions of greenhouse gases, related global warming, and dependency on fossil fuels, it is very important to promote the use of renewable energy, and in many parts of the world, in order to reduce GHG, they are taking efforts to convert biomass and organic waste into energy. Biogas technology plays a vital role in this, as livestock waste is considered to be a substantial source of ambient greenhouse gases, which causes climate change. In most developing and developed countries, Biomethanation technology has been promoted for the same.
As per data in 2019 provided by National Dairy Development Board, India sheltered 192.5 million castles and 109.9 million buffalos.
According to the United Nations Food and Agriculture Organisation, the animal waste on this planet produces around 55-65% of methane, which when released into the atmosphere can cause global warming 21 times higher than the rate of CO2. Cow dung is a very serious problem for people around the farm. The problem is often caused by cow dung which is not handled professionally. Its existence pollutes the environment and can act as a transmitter of disease.
The proper management of livestock manure has a much greater potential to reduce methane emissions, especially in the case of cattle manure, It should be emphasized that manure stored in piles is a source of important methane emissions, the scale of which may reach tens of thousands of tons per year.
Biomethanation Plant
Biogas plants can be designed and constructed as per the requirement, depending upon the amount of and the type of waste available and the amount of gas needed.
The unprocessed cattle dung or burning of the cattle dung is more dangerous as it emits greenhouse gases and CO2 and thus polluting the environment. Whereas the combustion of biogas provides a clean source of energy, as it does not produce soot, like firewood. This helps reduce indoor air pollution, which in turn prevents respiratory infections and associated diseases. It can be a good alternative to LPG which is getting costlier.
Biogas plants significantly curb the greenhouse effect: the plants lower methane emissions by capturing this harmful gas and using it as fuel. Biogas generation helps cut reliance on the use of fossil fuels, such as oil and coal, the most important of its many advantages is that biogas can offer a decentralized energy solution.
Economic Viability
Generally setting up Biogas plants is considered expensive, to promote and support sustainability, Govt. of Inda is supporting by providing subsidies for setting up biogas plants, which may range from 25000 to 5cr, and the payback period of a biogas plant is generally considered to be 3-4yrs. Besides supplying energy and manure, provides an excellent opportunity for mitigation of greenhouse gas emissions and reducing global warming and thereby earning carbon credit, which in turn can be encashed on a yearly basis, thus making biogas plants economically viable.
Biogas as an alternative to LPG for cooking
As the price of conventional cooking gas (LPG), is constantly increasing and becoming unaffordable for the major population, The gas produced from the biogas plant can be used as an alternative and thus affordable, as the gas is produced by the digestion of cattle dung, it is more economical and environment friendly.
Biogas as an alternative to electricity
The expenses on power used in a dairy processing unit are so huge as they must food processing units, and other major electrical appliances, the major expenses on the electricity can be reduced by converting the biogas produced to electricity by installing a biogas Genset.
Biogas as an alternative for pollution-free fuel
If the biogas produced from the dairy farm which may include the cattle dung and any organic wastes generated in the farm, is considerably high, it can be further purified to CBG, which is equivalent to CNG and can be used in vehicles or filled in cylinders and sold to restaurants and other industries.
Nutrient Rich BioManure and other Bioproducts
The slurry that is produced post the anaerobic digestion process, is considered black gold as it is very much rich in N, P, and K a very good fertilizer that can be sold to farmers.
Table – I Composition of Biogas Slurry/Vermicompost/ Cow Dung
| Slurry Type | Nitrogen (%) | Phosphorus (%) | Potash (%) |
| Digested Slurry | 1.5 – 2.0 | 1.0 | 1.0 |
| Vermicompost | 0.5-1.5 | 0.1 – 0.30 | 0.15 – 0.56 |
| Cow Dung | 1.19 | 0.3 | 0.48 |
The nutrient-rich bio manure can be further processed into Phosphate Rich Manure (PROM), which can be used as an alternative to DAP and thus maintain the fertility of the soil without adding any chemicals.
The electricity produced, and the sale of organic fertilizers either raw manure or processed manure as PROM are the most important sources of income that are expected from the biogas system.
These biodigesters can offer benefits to all spheres of society but are more beneficial to dairy farms. They can use the gas produced for cooking, running biogas generators, and fertilizing crops with the residual waste or sell them.
A farm with 100 cows can be benefited from the following.
| Biogas Produced | 16kg/ day |
| Annual Power Generation | 60 Units of Power per day |
| Central Financial Subsidy | 3.5 Lakhs (approx.) |
| Carbon Credit Claim (Annually) | 0.20 Lakhs |
| Bio Slurry obtained (Annually) | 2400 kg/yr. |
| Revenue Generated from Manure Sales (Cost @ Rs.1/ kg) | INR 24000/ yr. |
Thus, cow dung management can be efficiently handled which can help the farm owners benefit economically and contribute to the reduction of GHG and also fall in line with the different laws imposed by the pollution control board.
