An optimisation tool for minimising fuel consumption, emissions and costs from biofuel powered diesel generator-PV-battery hybrid mini-grids in developing countries

The purpose of this research was to develop a cost optimisation tool to improve the performance of diesel generators within hybrid microgrids for increasing electrification rates in rural areas of developing countries, especially in sub-Saharan Africa. This study considered the use of widely available vegetable oils, such as castor oil, to widen the fuel options to power diesel generators and reduce their environmental impact and operating costs. Castor oil-diesel blends were used to assess the performance of a diesel generator and find new fuel estimation equations, which were used to develop a cost optimisation tool for diesel/PV/battery microgrids. The best performance occurred above 60% engine load for all the blends and higher fuel consumption was found for the blends with higher castor oil content. The developed cost optimisation tool was used to compare the Levelized Cost of Energy (LCOE) and the pollutant emissions (CO2e, PM2.5, and NOx) of 8 microgrid system configurations for three estimated electricity demand profiles (high, medium, and low) in the Lindi Region in Tanzania. Installing diesel/PV/battery hybrid systems gives lower LCOE than diesel/battery or conventional systems (only diesel generators). Hybrid systems reduce CO2e emissions between 20% and 24%, whereas PM2.5 and NOx can be reduced between 32% and 47%, relative to conventional systems.