Bio gas unit produce cooking fuel or electricity. A viable small scale commercial bio gas unit should be minimum 2 cubic meter. It would require around 35 square feet area. There two different models with respect to waste, one is cow dung and other is kitchen/bio-degradable waste. Minimum waste to be fed in this unit everyday is 30 kg/day that produce 1-1.5 cubic meter gas. The cost would vary between Rs. 25-30 thousand. If the unit is set up in the farm then the farmer can take government subsidy. The percentage/amount of subsidy varies from state to state.
The slurry obtained is excellent manure for farming. However, it is strongly recommended to get the slurry tested in the laboratory to check on the nutrient content precisely NPK and other nutrients. If potash is less then it needs to be supplemented additionally in order to ensure the crops get a balance feed of manure as required.
There is no legal permission required to install the bio gas unit. If the farmer wants to claim the subsidy then the procedure needs to be followed and the installation needs to be done through bio-gas turnkey providers. They are being authorized by the zila panchayat to assist the farmer in all aspects.
Once the plant is set up then it is mandatory to run it every day. It can’t be shutdown even for a day atleast for minimum one year from installation. Later to which occasionally it might be kept running without feeding the raw material for 1-2 days then the pressure shall be reduced but the microbes alive shall be able to survive. But it is advised to keep the plant running always.
If the plant is set up for cow dung based unit then in it even poultry or goat dung can also be added. It is in a way good as the slurry obtained will have a good mix of nutrients but once again the slurry needs to be tested for the nutrients’ content. Subsequently it has to be supplemented as required by the crop.
When the safety aspect is considered bio gas is better than LPG. It is lighter than air hence it is safe unlike LPG that is heavier than air. In case of any leakage, bio gas escapes and gets mixed in the atmosphere therefore there is no probability to any fatal accident contrast to the LPG leakage that instantly catches fire.
Bio Gas is the most apt solution to turn waste into revenue. These days there are pre-fabricated small plants of 15 kg capacity are also available in the market. It is easy to install and run. The small plants come in plastic drum. It does not corrodes hence is maintenance free. The plastic is FRP that is fiber reinforced plastic, safe to use. For more details contact -
Dr. S Shamsundar, Director, National Institute of Engineering, Mysore
Email Address:
niecrest@gmail.com