| Application of biomass-energy technologies |
|VI. Conversion of biomass into electricity|
The ASTRA group in Bangalore (Ravindranath et al, 1990; Ravindranath and Mukunda, 1990) had carried out studies, at the micro-level, of biogas and producer-gas-driven electricity generating sets in the village of Hosahalli in Karnataka State. They believe that
"The field experiments at Hosahalli village have demonstrated so far the technical feasibility of a decentralized electricity generation system based on wood gasifier biogas technology for meeting various energy needs of remote rural settlements" (Ravindranath et al, 1990 p. 1975).
The wood gasifies provides gas to drive a 7 HP dual-fuel engine (80 per cent woodgas and 20 per cent diesel) and a 5 kVA 3-phase generator. The life of the engine has been taken to be 20,000 hours, after which the engine has to be replaced. The cost of the system is based on an operating time of 15 hours/day. Table 12 shows the operational and capital costs of a 3.7 kW wood system for generating electricity. The operational cost considering diesel and labour is Rs. 1.22 per kWh if wood is free, and Rs 1.54 if wood is to be purchased. The capital cost amounts to Rs. 63,600; in contrast, the capital cost of an equivalent engine running on diesel is estimated to be around Rs. 39,600.
According to Ravindranath and Mukunda (1990), at the current level of operation for lighting only for 4 hours/day, the wood-gasification system would be economic only if electricity is priced at Rs 3.5 per kWh. However, if the gasification system operates beyond 5 hours/day, the unit cost of energy becomes cheaper than the diesel system. The economic viability could be improved further by: (a) matching of the gasifier-diesel engine capacity (5 kW) since currently a 3.7 kW generator is connected; and (b) by diversifying the use of the gasifier system for meeting other energy needs such as pumping water which would lead to increased capacity utilization. At present, a subsidy is still required at this stage of development, but there is a strong possibility that the system will become economically viable in the near future. It should be noted that the centralized electricitygeneration and distribution systems are also subsidized in the district. For comparison, the present subsidized price of grid-based electricity is Rs. 0.65/kWh.
An important aspect of this project is that the villagers are prepared to pay over twice as much for their electricity (Rs. 1.3/kWh) because: (a) the supply is reliable; (b) it provides ancillary benefits (clean drinking water, flour mill etc.); (c) quality of supply; and (d) of emergence of self-reliance (the formation of a village management committee) (Ravindranath, in press).