What's cooking in India's largest biogas plant

Methan village in Sidhpur tehsil, Patan district of Gujarat saves 500 metric tonnes of fuelwood annually. They've been doing it for the last 15 years. This village is home to India's largest biogas plant, run by Silver Jubilee Biogas Producers and Distributors Cooperative Society Limited. "The biogas plant has been running since April 25, 1987, with minor repair works, and supplies gas to the villagers. Our cooperative runs the plant with no external assistance. This is the largest biogas plant in the country,' claims Kasimbhai Khan, former supervisor of the cooperative society.

Mehsana-based Dudh Sagar Dairy (dsd) and the state government's Gujarat Energy Development Agency had initially helped set up the plant. dsd officials approached the villagers with their plan for the plant, and educated them in the utilisation of cowdung to produce biogas. This, they said, would reduce both indoor pollution and dependence on firewood. With an aid of Rs 19.91 lakh from the then department of non-conventional energy sources (now, ministry of non-conventional energy sources) of the Union government, the biogas plant was inaugurated.

The biogas plant has eight digesters with a total capacity of 630 cubic metres (cum). Six digesters have a capacity of 85 cum each, and two have a capacity of 60 cum each. When the plant was used for the first time, 25 tractor trolleys of cowdung were fed into the digesters. Now the plant needs only one trolley of cowdung per digester. The digesters are used on a daily rotation basis.

Everyday, one digester is filled with a trolley of cowdung that is mixed well with water in a mixer-well. The cowdung then passes from the mixer-well to the digester. The temperature inside a sealed digester is maintained at 35