Optimum sizing of mini-grid wind power plant with energy storage system for rural electrification in Zambia: a case study of Mpika district

Abstract

The Government of the Republic of Zambia (GRZ) has set an ambitious target of raising the rural electrification rate from 3.4% (in 2008) to 51% by the year 2030.However, as at 2017 - almost 10 years down the line, the Rural Electrification Authority (REA) indicated that access to electricity in rural areas stood at only 4.4% which implies that, if things remain unchanged, the 51% rural access to electricity may not be achieved in the target year. In Zambia, the delay in rural electrification may be attributed to the sparsely settlement in rural areas as most rural communities are established away from each other as well as from the national grid and, hence, require huge investments to extend the national grid. It would be helpful for Zambia to consider exploiting other efficient and least-cost options for generating and supplying power to rural areas. This study employed a combined theoretical and applied approach to assess the technical and financial viability for setting up small wind power system with mini-grid to supply electricity to some rural areas as opposed to grid extension. Using the case of Mpepo Chiefdom in Mpika District, the study sized a wind power system with an energy storage system (ESS) and assessed its viability for rural electrification based on community’s energy demand and wind speed, and compared the cost of wind power system against grid extension. The study considered the Battery Energy Storage (BES) system and the Hydrogen Fuel Cells (HFC) as ESS for power back up in times of low supply. The study established that some parts of Zambia receive wind speeds higher than 4m/s and suitable for power generation as standalone mini-grid system for rural electrification. Based on the financial analysis in this study, the WPP without ESS would offer a cheaper option than the WPP-HFC and WPP-BES systems. However, on account of reliability and stability of power supply, the WPP-BES system would to be more viable than the WPP without ESS and, would also provide a least cost option compared to WPP-HFC. Further, the study revealed that for communities experiencing wind speeds of 4m/s and above, and located more than 74Km from the point of connection to the national grid, the WPP-BES would be a least cost option compared to the grid extension. Based on the foregoing, the study recommends that rural areas, whose locations are in high wind zones and more than 74km from the national grid, be considered for electrification using the WPP-BES. Keywords: Rural electrification; wind power plant; grid extension; mini-grid, electrification rate, technical and financial viability.