Techno-economic analysis of an islanded energy system based on geothermal/biogas/wind/PV utilizing battery technologies : a case study of Woulde, Adamawa's region, Cameroon

The present paper performs a techno-economic and an environmental analysis of an islanded energy system based on Geothermal/Biogas/Wind/PV hybrid energy system using two battery technologies for electricity generation in the city of Woulde in Cameroon. The innovation of the present paper is threefold: (i) a geothermal plant was modeled, and coupled to various power sources and battery technologies; (ii) an environmental analysis of the hybrid system was performed; and (iii) a solar dual-axis tracker (DAT) was incorporated in the system. The study findings suggested that the integration of a DAT reduced the battery requirements. The results demonstrated that integrating the DAT in the architecture minimized the levelized cost of energy, i.e. from US$ 0.271/kWh to US$ 0.260/kWh for lead-acid (LA) batteries, and from US$ 0.269/kWh to US$ 0.256/kWh for lithium-ion (LI) batteries. It was revealed that the net present cost varied from US$ 61.3 million to US$ 58.9 million for LA batteries, and from US$ 61.0 million to US$ 58.0 million for LI batteries. For both energy storage technologies, the use of a DAT improved the photovoltaic electricity production (about 32.0 % more power). The solutions also revealed that the monthly electricity production of the biogas generator increased with the use of a DAT (about 227.74 % and 7.16 % more power with LA and LI batteries respectively). Concerning the monthly electricity production of the geothermal generator, it decreased with the use of a DAT (about 15.30 % and 7.96 % less power with LA and LI batteries respectively). In addition, the integration of a DAT in the hybrid system increased the emissions of Carbon dioxide and Carbon monoxide. The computation of the excess of electricity revealed a variation from 6,439.0 kWh/year (for fixed system) to 1,676.0 kWh/year (for the system incorporating a DAT) when the LA storage technology was used. For LI technology, it was shown that the excess of electricity increased from 657.0 kWh/year (for fixed system) to 2,420.0 kWh/year (for the system incorporating a DAT). It was also found no unmet load in the different architectures implemented, which simply indicated that the energy produced by the scenarios covered the electricity needs. It was also demonstrated that the electricity production was largely dominated by the geothermal plant for all the scenarios, followed by the PV panels, biogas, and wind turbine generators. It was also found that the wind turbine electricity generation was mainly recorded during the months of January, February, March, and December.