Jatropha curcas oil, powering conventional small diesel generators, provides a low cost method of providing electricity for illumination to thousands of African villages. This practice complements the use of wood-fired power plants and hydroelectric power for grid electrification, serving large cities and secondary towns. Jatropha curcas oil is a more expensive energy source than wood, but is economical for the small amounts of electricity required for village electrification. Small autonomous village electrification projects can be implemented at a small fraction of the cost required to extend grid electrification to rural areas.

The efficiency of the diesel generator and wood-fired power plant is very similar; roughly 20 to 25% of the energy in the fuel is converted to electricity. A diesel generator consumes roughly 0.4liters (0.36 kg) of Jatropha curcas oil per kilowatt-hour of electricity produced. At a price $0.50 per liter, currently practiced in Senegal, the energy cost per kilowatt-hour is $0.20. By comparison, a wood-fired power station uses 1 kg of air dried wood per kilowatt-hour, though at a cost of only $40 per ton ($0.04 per kg); this gives an energy cost of $0.04 per kilowatt-hour. Costing five times as much as wood, Jatropha curcas oil is clearly uneconomic for large scale power generation, just as it cannot compete with wood as fuel for cooking. Its important niches are for small stationary diesel engines, where fuel consumption is modest, and for transportation, where wood is at best an inconvenient fuel.

The affordability of village electrification based on Jatropha curcas oil depends on the efficiency with which the electricity is distributed and used. We envision distribution within a smal1 radius, probably no more than 500 meters, from a centrally located generator. While inexpensive aluminium and even steel fence wire may be used for distribution because of the short distances and low amperages, the wire should be properly sized to keep distribution loss below 10%. The European standard 220 volt 50 hertz service gives lower line loss than U.S. 110 volt service, and can be used for village scale electrification, avoiding the need for expensive transformers.

The capital cost of village electrification can be reduced by using a single engine to power the village generator (alternator) and cereal mill. The engine would be placed between the two loads so that the transmission belts can be moved from the mill to the alternator or vice-versa. A more could drive the mill or alternator. This would allow continual service while one engine undergoes maintenance. It is not advisable to use electricity from the alternator to drive the mill via electric motor because the combined losses of the alternator and motor would increase fuel consumption for rnilling by about 25%. This would require a more powerful engine and alternator. In the case of larger village electrification systems, the alternator capacity would be substantial1y larger than the load of the village cereal mill (5 to 8 kilowatt), and electricity may be needed during the daytime for refrigeration and other purposes.

Village electricity users will use the same 20 and 40 watt florescent tubes as their urban counterparts, having probably less than 100 watts of lamps per family. Assuming that three hours of light are provided per day, a family would use : roughly 10 ki1owatt-hours of e1ectricity per month, requiring four litres of Jatropha curcas oil at. a cost of $2.00. Poorer families would use less than half this much energy. Families would be billed according to the
total wattage of their installed lamps and appliances, on the assumption that these would be used continuously for the duration of electric service. This would avoid the high cost of metering each household. Such a system could be operated by existing vi1lage governance, on the basis of popular consent and arbitration.

Vil1age electrification is a1most non-existent in most African countries, and villagers often respond to the idea with incredulity or skepticism, believing that rural incomes are too low to support the 1 costs. On the other hand, when asked whether the use of electricity would improve their quality of life, villagers almost uniformly believe it
would. Village women in particular mention the difficulty of cooking and caring for their children after dark, particularly during the rainy season, when they are busy in the fields during the day. While many villages will not be able to afford the capital cost of electrification, those that have cash crops like coffee, cocoa, or cotton are in a good position to do so. The production of electricity from a locally grown fuel is essential to its long-term affordability, and provides income to farmers who grow Jatropha curcas seed, who extract oil from the seed, or who use the seed cake to fertilize their crops.

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last modification  07.06.02