Evaluation of power performance and economic viability of a wind-solar hybrid energy system for Installation in Low Wind Speed Regimes in Kenya.

Abstract

Global energy sector is rapidly shifting into renewable-based energy generation technologies, these being the most realistic avenues for avoiding the worst effects associated with conventional energy sources. This shift is motivated by the urgency to have safe energy, attain sustainable development and limit climate change. This study evaluates the power performance characteristics of a wind-solar hybrid energy system and its viability for installation. A wind turbine rotor was installed at a hub height of 8 m, then hybridized with solar PV for field tests. A data logger was connected to the controller interface for data collection. Wind shear analysis was conducted to determine the power extractable at higher turbine hub heights.  At a turbine hub height of 8 m to 100 m, average wind speed range of 3.2 m/s to 6.0 m/s with power density range of 20 W/m² to 140 W/m² is reported. The hybrid energy system (HES) generated an average of 36 W from wind and 143 W from solar, which translates to 0.864 kWh and 0.835 kWh for 5.84 peak sun hours, respectively. Wind shear analysis projected a wind speed of 5.1 m/s at a turbine hub height of 50 m translating to a power density of 79 W/m². This power density would generate 5.4 kWh daily, which is comparable to the daily energy need of 3.432 kWh estimated at 50 m using the power law. The investment cost of the hybrid system was USD 631 based on which its economic viability was determined at a discount rate of 6 % p.a. Installation of the HES was found economically viable with a net present cost of USD 537, a payback period of 5.47 years and a profit index of 1.85. The study projected that a single household would reduce 2.11 tons of CO₂ within the 20-year system economic life span. With these findings, a hybrid energy system was found to be more flexible and a feasible solution to wind and solar intermittence. Moreover, HES has been found to be economically viable for installation in low wind speed regime areas.