Review on Liquid Piston technology for compressed air energy storage

International audienceCompressed air energy storage systems (CAES) have demonstrated the potential for the energy storage of power plants. One of the key factors to improve the efficiency of CAES is the efficient thermal management to achieve near isothermal air compression/expansion processes. This paper presents a review on the Liquid Piston (LP) technology for CAES as a timely documentary on this topic with rapidly growing interests. Various aspects are discussed including the state-of-the-art on LP projects all over the world and the trend of development, the coupled fluid flow and heat transfer during the compression/expansion operations, and different actions proposed and implemented to enhance the heat transfer inside the piston column.It has been found that LP is a promising concept for isothermal CAES. However, the complex and transient fluid flow and heat transfer behaviors inside the LP are difficult to characterize and master. To enhance the heat transfer and increase the efficiency of the compression/expansion processes many approaches have been tested including liquid spray, wire mesh, porous media, optimal trajectory, hollow spheres and optimal geometry of the piston column. Numerous empirical correlations of Nusselt number have also been proposed to estimate the heat transfer in different types of LP, as reviewed and summarized in this paper