Feasibility study of an optimized solar-biomass hybrid power plant for University of Rwanda: Case study for college of science and Technology

Abstract

Rwanda Energy Group intends to increase the capacity of solar power plants to diversify the energy resources and to electrify rural areas by using this available resource so that by 2024 all Rwandan population will have electricity access through both on grid and off grid electricity generation systems. However, solar energy is unpredictable, intermittent and seasonally unbalanced and may not provide the greater security of supply system. The combination of solar energy with wind, biomass and hydro energy provides high portion of electricity demand with reliable and consistent power supply. Hybrid renewable energy system uses more than one renewable energy resource to increase the generation and system efficiency. Therefore, this Thesis work is mainly focused on feasibility study of an optimized hybrid power plant consisting of solar and biomass resources available at University of Rwanda- College of Science and Technology. The main purpose of this research work is to determine the feasible optimum model and performance of a hybrid energy system based on solar and biomass energy sources, which will satisfy the electrical energy demand for the College to replace the conventional grid system by making the college self-sufficient in its electric power need. The college hosts 7000 people including students, staffs, securities and other casual workers. The first part of this this research work was to assess the potential of solar and biomass resources as well as energy demand estimation and forecasting for the college. As per the assessment, the average energy demand for the college is 2230 kWh per day including the future load growth and by considering a minimum solar radiation of Gmin 4.54 kWh/m2/day, 8.5ton/day average biomass input produced in the College, a hybrid model was designed and evaluated using Homer software. Various combinations of components have been integrated in the system to find the optimum size for Hybrid Renewable energy system. In the result, different configurations of the system were evaluated according to their net present cost, from the least to the highest and the result having the least net present cost was considered the most feasible. The feasible configuration is found to be the one which contains 160 kW photovoltaic array, 200 kW Biogas generator, 469 Surrette 6CS25P Batteries and 180 kW converter with cost of energy COE $ 0.2001 and total net present cost $ 1,500,807. This system has zero unmet load and zero capacity shortage with electricity excess of 276 kWh/year and it has low COE compared to National tariff. This is the reason why this system has been selected for its Least Cost of Energy.