Integrated Renewable Energy and Resource Network Optimisation for Off-Grid Energy Supply to Rural Communities

This study develops an optimal integrated energy network for 15 decentralised rural neighbourhood structures (sectors and clients) that are isolated from the main energy grid in Tsumkwe, Namibia. The structures have different demand profiles dictated by the type of building, the time of day, as well as the season. Because of the logistical difficulty and cost implication associated with bringing fuel (such as diesel) from distant suppliers to remote locations, the isolated communities need to make optimum use of the locally available biomass resources and have effective planning of outsourced fuel in their supply chain (SC). Biomass resources considered in this study are animal dung, fuel wood, human waste, and crop residue. These biomass sources were coupled with photovoltaic (PV) units and lithium storage batteries. The optimal network showed PV-SC selection with minimal battery storage selection. The SC shows a favourable cost advantage over the energy storage batteries and can support most of the intermittency of the PV supply. The SC contributed 94.1 % and 42.7 % with regard to the total cost and energy supply to demand structures. The PV panel was the preferred energy supply technology for the Distributed Energy System (DES) because of its cost effectiveness (57.2 % and 5.94 % energy and cost contribution to the network). The total annual power supply of the minigrid is 0.465 GWh/y. The total annual cost (TAC) of the minigrid was found to be N$ 2,580,000. The minigrid power production cost was found to be 39 % more expensive than energy from the National grid tariff. However, it does not require long-range transmission and makes provision for local job opportunities.