Vivekananda Kendra - Natural Resources Development Project (VK- NARDEP)
has sold and installed 2,000 biogas plants in southern Tamil Nadu,
India, to provide clean biogas for household cooking and fertiliser from
the biogas residue.
The southern part of Tamil Nadu is hot and humid. Most people work in
agriculture and grow rice, sugar cane, mangoes, coconuts and a range of
vegetables. The biogas plants sold by VK- NARDEP use cattle manure to
produce biogas which saves fuelwood, allows cleaner cooking and gives a
healthier environment, with reduced air pollution and fly-borne
diseases. VK- NARDEP has also recognised the significant potential of
the output residue from biogas plants. This is normally used directly as
a fertiliser and weed suppressor which gives significant benefits in a
rural agricultural environment. The value of the residue can be
increased by using it to grow Azolla, a nitrogen-fixing fern used as
animal fodder or green manure. Alternatively, the residue can be made
into an improved fertiliser using vermin-composting techniques. The
financial savings from avoiding the purchase of wood and chemical
fertiliser allow the cost of a biogas plant to be paid back within two
to three years.