Experimental investigation of the power storage system for Savonius turbines in wind and water

The Savonius turbine is practical in generating off-grid electrical power for hydrokinetic applications due to its simple design, particularly for small rivers in rural areas. However, despite many studies on methods to improve turbine performance, the electrical aspect of the turbine system is rarely discussed. Therefore, the present study aims to evaluate the performance of a simple and affordable power storage system using a conventional 2-bladed Savonius turbine. The experiment was conducted in a wind tunnel and a water channel with flow speeds of 6 m/s and 0.33 m/s, respectively, corresponding to a Reynolds number of 62700. A power coefficient of 0.09 was discovered for the wind experiment and 0.11 for the water. The total amount of energy extracted from the water was 60% less than from the wind due to the lower available power. It was observed that the tip speed ratio decreases over the charging period due to the constant current and voltage of the Lithium-Ion batteries. This will allow for a fluctuation in the amount of required current and consequently affect the torque needed to spin the generator. The findings confirmed the functionality of the electrical storage system and contributed to the low manufacturing and maintenance cost of the hydrokinetic turbines.