The Appropriate Rural Technology Institute (ARTI) in Pune has developed a biogas plant which uses food waste rather than manure as feedstock and supplies biogas for cooking. The plant is sufficiently compact to be used by urban households, and over 700 are currently in use. Pune is a relatively affluent city in south India, and many people use liquid petroleum gas (LPG) or kerosene for cooking. Waste food is often discarded at the side of the road, as in many cities, attracting stray dogs, flies and rats and creating a public health hazard. The ARTI compact biogas plant is made from two standard high-density polyethylene (HDPE) water tanks: the larger tank acts as the digester and the smaller one is inverted and placed into it to serve as a gas-holder. The plant safely digests kitchen waste, food waste or waste flour from mills, thus reducing the problem of waste disposal. A 1,000 litre plant produces sufficient biogas to at least halve the use of LPG or kerosene for cooking in a...