Experimental assessment of compressed air energy storage (CAES) system and buoyancy work energy storage (BWES) as cellular wind energy storage options

This paper presents the experimental evaluation of two compact energy storage devices directed towards wind energy storage applications. The first is a compressed air energy storage (CAES) system with its low infrastructural cost, easy coupling with existing wind resources and high round-trip efficiency. The second system utilizes the harvesting of the work of buoyancy forces resulting from submerging styrofoam buoys in a liquid at times of abundant energy supply and harnessing energy back by allowing them to ascend when demand arises. While the systems considered here are compact in size, the results obtained on performance parameters such as efficiency of energy conversion and electrical output are sought to be generalized as a storage option for real offshore wind farms. The main challenges in designing larger systems are the heat generated due to air compression and the considerable friction drag affecting the buoys. Larger systems, however, have higher potential energy enabling them to operate at higher pressures and depths for the compressed air and the buoyancy systems, respectively. The proposed modular systems, composed of many cells of air cylinders or buoys are expected to decrease heat and friction losses intrinsic to large-scale systems while at the same time reducing infrastructure costs and transmission losses and enhance overall energy efficiency.