Biogas, as you know is a source of energy for cooking. Using a simple process, cattle dung is used to produce a gas (called biogas) that contains 55-70 per cent of inflammable methane gas. It is a clear and efficient fuel for rural areas. Water weeds like water hyacinth, water lettuce, salvinia, hydrilla, duck weeds and algae are found to be useful supplement to cattle dung. Biogas can also be used to generate steam, which in turn may be used for running engines or machines in factories or for running turbines to generate electricity. Biogas plants (see Fig. below) can supply the needs of a number of families or even small villages.
The residual dung or the digested slurry left after generating biogas can be used as manure for agricultural purposes. ‘Ibis is an economical way of obtaining energy from organic wastes. In India, great efforts are being made to install thousands of biogas plants in rural areas.