Human energy requirements in Jatropha oil production for rural electrification in Tanzania

Abstract

Mini-grids connecting households to a generator can be a solution for providing rural communities in developing countries with electricity. Substituting diesel with locally produced Jatropha oil can improve economic and environmental sustainability of rural electrification. Jatropha is known as a labor intensive crop, but little is known about how inclusion of human energy input will affect the energy balance of production of Jatropha oil. In this study we investigate human labor requirements in rural electrification with Jatropha oil. Jatropha in this study in Tanzania was grown as living fences and provided multiple benefits. An energy flow chart of generation of electricity from Jatropha oil is presented, and it is shown that human energy expenditure in production of Jatropha oil is small relative to the overall energy in the system. Time consumption however is extensive, and 7.5 hour work is required to harvest and de-hull Jatropha fruit equivalent to 1 kg Jatropha oil. 1 kg Jatropha oil can in turn provide the community with 2.5 kWh electricity through a Multi Functional Platform connected to a local grid. Potential income from harvesting Jatropha is considered so low in the study area that farmers are reluctant to venture into it. Poorer people and children in the community are allowed by the farmers to harvest for free. Collection of seeds for Jatropha oil depends on the availability of labor willing to work for an income of approximately 0.9 USD/day. Social and economic sustainability of rural electrification based on Jatropha oil can be enhanced through generous subsidy.