THE POTENTIAL OF BIO GAS

The enormous potential of biogas, estimated at 17,000 MW can be seen from table 1. The capacity was derived principally from estimated agricultural residues and dung from India's 300 million cattle. Biogas technology may have the potential to short-circuit the 'energy transition' Leach (1987) describes from biomass to 'modern' fuels. Biogas technology is a particularly useful system in the Indian rural economy, and can fulfill several end uses.

With the bourgeoning population in metro cities and growth of urban centres, the enormity of waste generated is proving to be a huge task for disposal by city municipal  authorities. Therefore, this process, driven further can turnout to be best boon in waste management. The scope for saving huge funds used for transporting the waste as at present is immeasurable. Also the search and location for land-fills and promotion of pollution in areas nearer to urban centres can be avoided.

The gas is useful as a fuel substitute for firewood, dung, agricultural residues, petrol, diesel, and electricity, depending on the nature of the task, and local supply conditions and constraints (Lichtman, 1983), thus supplying energy for cooking and lighting.

Biogas systems also provide a residue organic waste, after anaerobic digestion, that has superior nutrient qualities over the usual organic fertilizer, cattle dung, as it is in the form of ammonia (Sasse et al, 1991).    

Anaerobic digesters also function as a waste disposal system, particularly for human waste, and can, therefore, prevent potential sources of environmental contamination and the spread of pathogens (Lichtman, 1983). Small-scale industries are also made possible, from the sale of surplus gas to the provision of power for a rural-based industry, therefore, biogas may also provide the user with income generating opportunities (KVIC, 1993). The gas can also be used to power engines, in a dual fuel mix with petrol (Jawurek et al, 1987) and diesel (KVIC, 1993), and can aid in pumped irrigation systems.

 Apart from the direct benefits gleaned from biogas systems, there are other, perhaps less tangible benefits associated with this renewable technology. By providing an alternative source of fuel, biogas can replace the traditional biomass based fuels, notably wood. Introduced on a significant scale, biogas may reduce the dependence on wood from forests, and create a vacuum in the market, at least for firewood (whether this might reduce pressure on forests however, is contestable).