Techno-economic viability of husk powered systems for rural electrification in Uganda: Part I: Sustainability and power potential aspects

Abstract

Rural electrification by biomass gasification is a fairly new technology in East Africa. A Husk Power System (HPS) is one of such technologies utilizing agricultural residues as feedstock for power generation. Since biomass is considered carbon neutral, replacement of fossil fuel-based electricity by HPS derived electricity is one way to mitigate climate change through greenhouse gas reduction. Uganda is one among the countries in Africa having limited modern energy services such as electricity, though endowed with abundant biomass resources. Limited technical capacity to efficiently utilize biomass resources has been one of the major constraints of modern energy accessibility. In the more advanced developing countries like India however, efficient and environment-friendly technologies, such as HPS, have been developed and disseminated. In this study, a pilot HPS was imported from India and installed in Tiribogo village, Muduma Sub-county, Mpigi district in 2012 to supply electricity to rural communities through an isolated grid. But before extending such modern energy service to other parts of the country, there was a need to assess its technical performance, power potential of the fuel source and its sustainability in the selected agricultural rural areas. Coffee husks and rice husks were considered as fuel sources of a 34 kWe HPS. The plant was operating for 6 h per day at a specific fuel consumption rate of 0.798 and 1.235 kg/kWh and overall conversion efficiency of 28.6 and 23.4% for coffee husks and rice husks, respectively. It was found that 36,355 tons of coffee husks and 12,591 tons of rice husks, equivalent to 21.1 and 4.6 MWe basing on HPS performance, were generated annually from coffee and rice processing villages; this could sustain a total of 615 and 136 HPSs, respectively. However, it was more difficult to operate and sustain HPSs in villages connected to grid electricity and villages generating less than 480 tons of rice husks per year.