Architecture, Instrumentation and Control of Liquid Piston Compressor for Energy Storage Applications

Efficient energy storage can address the local intermittency of renewable sources, with isothermal liquid piston (ILP) compression emerging as a viable solution that enhances the efficiency of compressed air and cryogenic energy storage. This work presents the advantages of the ILP, which has provided improved reliability and repeatability during longterm testing with autonomous control. The presented ILP (mk1) utilizes pressure and liquid level sensors with high accuracy and swift response for control sequencing. The results for selection of gas outlet valve, liquid carryover, pressure surge during discharge, bulk temperature under steady state, influence of cylinder materials etc., are contrasted to the earlier ILP (mk-0). The 35 minutes of operational results showed nearisothermal compression, with the end gas temperature at only $31^{\circ} \mathrm{C}$, compared to $\sim 300^{\circ} \mathrm{C}$ for a 3 to 30 bar adiabatic compression. Hence, establishing the foundational architecture, instrumentation and control requirements of ILP for successful application in energy storage systems.