Performance assessment of buoyancy work energy storage system with various buoy materials, coatings, and gasses

This study investigates the performance of a buoyancy work energy storage system. The sought operational and efficiency enhancements were examined by coupling various permutations of buoy material, working gasses, buoy surface coatings, and applied loads. A plastic buoy and a polyvinyl chloride (PVC) float are used as they are common materials for buoy construction. Both buoys are filled with different gasses, namely air and helium and examined with and without a lubricating exterior silicon coating. The air and helium-filled PVC floats exhibited the best energy output performance across the different loads, whereas the original plastic buoy performed the poorest. The inclusion of the silicon coating on the external surface of the PVC floats resulted in an energy output performance enhancement of 15.44 % and 5.01 % for air and helium-filled PVC floats, respectively, and a 4 % efficiency enhancement overall. However, the greater required input energy to descend (system charge) the silicon coated helium-filled PVC floats caused efficiency losses, with peak efficiency reaching 24.18 %. However, the silicon coated air-filled PVC float reached a higher maximum of 29.61 %. Moreover, Analysis of Variance (ANOVA) test was carried out to investigate the system performance dependence on the presented variables. Consequently, a scaled-up version of the proposed buoyancy energy storage system was presented to be utilized in the London Array offshore wind turbine farm, with a LCOE of 0.978 ¢/kWh. •Design and analysis of a mechanical energy storage system for off-shore wind turbines•The system is simple and modular. It can be scaled up with ease.•Utilizes buoyancy principle and the work of the resulting force•An experimental rig was constructed to test different buoy materials and surface coatings.