The traditional farmers in the state of Kerala, in India have mostly small holdings which are well under one hectare. These homestead farms are under multi-cropping systems with several perennial crops grown side by side. To make the system viable these fragmented farms are integrated with various sub-systems like, dairying, poultry, apiculture, piggery etc. The high amount of biomass and the large quantity of the crop residues which are usually wasted and cause pollution can be effectively utilized to produce energy for the farm.
The Deenabandhu type of biogas plant with a fixed dome is a very popular model in the country. The size of the plant is decided by the quantity of feed material regularly available on the farm. The animal dung, animal urine, crop residues, food wastes and even slaughter house waste can be successfully digested to produce biogas. The plant is a simple and practical model as it does not require any additional power source for feeding it as well for the slurry removal.
The biogas plant has been found to be a very viable solution for the garbage disposal also. The hotels, slaughter houses and the public markets find it a practical solution not only for energy production but also for the safer and economical disposal of the wastes. The biogas slurry is enriched manure, which can be applied to the crops directly as slurry or composted in separate tanks with the crop residues of the farm. The slurry has been effectively used for the backyard kitchen garden in the villages as well as the rooftop vegetable gardens in the towns.
Biogas plants, provide very practical solutions to the energy supply, garbage disposal as well as soil nutrition. It is even more viable as it can work just on the recycling of the unutilized resources. The ambient climatic conditions of the humid tropics, makes it a very economical and eco-friendly option. Presently, the gadgets available to utilize the biogas are biogas stoves, used for cooking and the biogas lanterns for lighting in the farms. Biogas engines are other options available in the market are expensive and not viable for the small farm operatives. More studies are needed to improve the efficiency of the existing designs as well as to develop gadgets for utilizing the energy for the various operations in the farm.