Techno-economic analysis and dynamic power simulation of a hybrid solar-wind-battery-flywheel system for off-grid power supply in remote areas in Kenya

Sub-Saharan Africa (SSA) has the lowest energy access rates globally. The need for transformative energy sources ranging from solar off-grid and mini-grid solutions to hybrid micro-grid power systems has rapidly grown to deliver clean energy admittance. This research proposes a hybrid photovoltaic-wind turbine power system coupled to a hybridized storage system composed of a Lithium-Ion battery and a flywheel storage system which ensures reliability for off-grid electrification for rural and less accessible remote areas of Makueni County in Kenya. The optimal size of the proposed Hybrid Renewable Energy System (HRES) is estimated, using a multi-objective optimization modeling approach, taking into account the Levelized Cost of Electricity (LCOE) and reliability (energy index of self-reliance (EISR)) of the system as the main objective functions, using epsilon (epsilon)-constraint technique as the solving approach. A resultant Pareto front is analyzed to obtain the best compromise for COE at 0.519 USD/kWh and reliability indicator, energy index of self-reliance (EISR) at 0.997. The optimal size of the HRES was realized at 26 PV panels (330 W) and 3 wind turbines (1 kW) which satisfies the annual local load requirement of 37.94MWh. Next, the hourly performance of the proposed HRES, under different operating conditions, is evaluated, using a dynamic power control simulation model developed in Matlab-Simulink. The results revealed the proposed off-grid HRES is highly reliable, meeting the load demand sufficiently in all meteorological conditions experienced in the area of study. Furthermore, adopting a hybrid energy storage system (HESS) realized an annual potential of 858kWh storage capacity gain in the battery when coupled with the flywheel storage system.