Thermo-chemical storage for renewable energies based on absorption: Getting a uniform injection into the grid

Renewable energies, such as solar, wind or wave energies show intermittent production patterns that complicates their injection into an electrical grid. In order to overcome this inherent drawback, this paper proposes an innovative permanent storage system that uses both thermal and mass transfer internal processes based on absorption to store mechanical/electrical energy at large scales. This enables a manageable smoother power output to the grid, more suitable for trading. The system consists of two storage tanks for accumulating a liquid solution at two different pressures, connected with a compressor and an expander of the vapor absorbed/desorbed. An additional heat exchanger allows for recovering the absorption heat from the high-pressure tank seeking for storage efficiency. A detailed numerical simulation has been developed in order to predict the performance of the storage system under transient operating conditions and to determine the appropriate design parameters. The results show interesting and relevant conclusions about both the energy exploitation and the efficiency parameters of the energy storage system for reducing the intermittent electricity production.