Techno-Economic design of reliable wind-solar hybrid energy system with battery storage for off-Grid electrification of pate Island in Lamu,Kenya

Abstract

Approximately 1.5bn world population don’t have electricity access and most of them live in offgrid locations[2,3]. Major source of electricity in off-grid locations is diesel generator. Occasional increase in fuel price leads to increased electricity cost. Greenhouse gas emission, noise and smoke from diesel generator pose negative environmental effects. Frequent blackouts due to generator failures [1] in these areas result to system unreliability. There is need to find solutions to the challenges posed by diesel generators through adoption of renewable energy source like wind and solar. System of hybrid renewable energy is capable of meeting high energy demand and solving the challenge of individual energy resource intermittency[2]. This study aims to achieve technical and economic design of reliable wind-solar hybrid energy system with battery storage for Pate Island in Lamu, Kenya. Theoretical modeling of the hybrid system components capacity and cost was achieved by reviewing previous publications. Twenty-year average of wind speed (7.55m/s), solar radiation (6.25kWh/m2/d) and temperature (27.200C) values were obtained from MERRA-2 satellite data. Electrical load assessment was based on 2019 Kenya energy access diagnostic report based on the multi-tier framework. HOMER Pro software was used in design, simulation and optimization of various hybrid systems capable of meeting load of 4891kWh/d. 10 hybrid configurations and standalone diesel generator were feasible. Set of evaluation criteria that include zero capacity shortage, zero emission, cost of energy within the range of tariff for renewable energy projects in Kenya and lower discounted payback period were used. The best hybrid system was solar PV/Wind turbine/battery consiting 815kW Photovoltaic array, one-660kW wind turbine, battery storage capacity of 16,305kWh and 757kW bi-directional converter. Cost of energy of US$ 0.153/kWh, discounted payback-period of 10.05yrs, internal rate of return of 13.8%, initial capital cost of US$ 2.35M, O&M of US$ 54,314/yr and net present cost of US$ 3.04M.