Design and Optimisation of PV-Biogas Hybrid system for rural electrification in Rwanda

Abstract: Access to clean energy such as electricity, is a problem and challenge for utility companies in developing countries. Diesel engines for generation of electricity have been used for remote rural villages, but extensions of the electrical grid are often not economical considering the low power demand relative to the costs. Furthermore, fossil fuels are expensive and not environmental friendly adding to the climate change with greenhouse-gases. Other options are needed. This thesis suggests a hybrid system with renewable energy sources, consisting of PV and biogas with a battery storage. The system is designed for application in a village of Gakenke district in Northern part of Rwanda. An inventory of existing renewables is made and the village’s load profile is estimated. The hybrid system is modelled and optimized for technical and economic viability using the HOMER software. Two alternatives based on 42 respectively 21 tons of biomass, can give 88.86 MWh/year to a cost of $0.130/kWh and 87.35 MWh/year to a cost of $0.154/kWh. These figures are compared with an optimized solar home system with the cost of $0.457/kWh and the current electricity price of $0.240/kWh. Based on these optimized results it is evident that a hybrid system with PV and biogas is more cost-effective than the solar home system and the current price for electricity. Hence, the implementation of off-grid hybrid systems can be a solution for remote rural electrification in Rwanda.