Developing a Pilot Biogas-Solar PV System for Farming Communities in Botswana: Case of Palapye

Abstract

Palapye is one of the fastest growing urban centers in Botswana. The projection of this urbanization shows a subsequent high rate of waste generation in the future with a composition of over 50 % of organic compounds from discarded foods. Several studies show that there is currently no effective waste management system in this town. For this reason, this paper sought to succinctly propose the design of a pilot 9 kW Biogas-Solar Photovoltaic (PV) Hybrid Mini-grid (BSPVHM) as a tool for an effective waste management plan and an alternative energy and agricultural solution for local farming communities. The designed pilot BSPVHM is composed of four sections which are the power generation section (with a 5-kW biogas and a 4 kWp solar PV power units), the power back-up section (with a 5 kVA diesel genset and a 6-kWh lithium-ion battery), the energy management system (EMS) section (with a 4.6 kW inverter and remote and on-site monitoring instruments) and the power supply section (with a low voltage cable). The town of Palapye was selected as the site of the pilot project because of its high waste generation capacity estimated at an average of 0.20 kg/capita/day from various categories of domestic sources. Additionally, the noticeable presence of farming communities and the yearly solar photovoltaic power potential ranging between 1753 - 1899 kWh were other reasons for this selection. Based on these available ressources, it was assumed that BSPVHM will supply at domestic scale, solar power from panels for 12 hours from 6 AM to 6 PM, power from the biogas generator for 6 hours from 6 PM to 12 AM and power from the back up section from 12 AM to 6 AM. The supply of electricity will be done autonomously by the BSPVHM system under a limited physical monitoring.