Solar-diesel-storage Hybrid Electrical Energy Access System Design and Optimization: Case of Unhcr Sub-office in Dadaab, Garissa County, Kenya

Abstract

The world’s latest strive involves the eradication of conventional fossil fuel utilization in electricity production. This is not only expensive but contributes a lot towards climatic change through the increased production of greenhouse gases that would have an eventual effect on global warming thus climatic change. Further effects also include environmental pollution and acidic rain which would cause corrosion. The existence of fossil fuels is also in doubt considering their extinction and security risk. In this spirit, governments across the world have been encouraging the venture into green energy supplies such as Solar Photovoltaic systems through the introduction of incentives to cushion the high prices of solar modules and their associated accessories which can be evidenced by the 21% increase in Solar PV penetration from 156 TWh in 2019 to 821 TWh in 2020. This research covers the UNHCR Sub-Office in Dadaab henceforth referred to as the facility. The analysis of the utilization of fossil fuels at the facility has proven to be expensive with cumulative costs approximated at as much as $493,853 annually translating to a unit electricity cost of about $0.362/kWh in the years 2020 and 2021. The carbon emissions have also skyrocketed thus increasing the carbon footprint to over 1,084 tCO2/yr. Over 1,158 simulations run by the HOMER software yielded 868 feasible solutions with a preferred hybrid solar PV system capacity of 756-kWp encompassing 443-kWh battery storage and one of the 550-kVA generators already installed at the facility. The system would command a renewable energy penetration of 60% with the remaining energy supplied by the diesel generator. The Energy conservation measures applicable at the facility were also explored with LED lighting retrofit coming out as a low-hanging fruit due to the huge amount of conventional fluorescent and incandescent luminaires currently installed. The economics of the proposed solar PV system is attractive for investment with the simple and discounted payback periods at 5.42 and 6.85 years respectively depicting a short time considering a 25-year lifetime. The simulated LCOE incurs a significant 21% drop from $0.31 to $0.246 for the base and proposed system respectively with a 17.5% IRR and 13% ROI further making a case for the feasibility of a renewable energy hybrid system over the sole conventional diesel power generation. The annual carbon emissions reduction is impressive at a 46% reduction.