Benchmarking of liquid air energy storage with and without added firing against batteries and gas-fired power plants

Rapid deployment of variable renewables is broadly viewed as the primary mechanism for reducing the carbon intensity of electricity systems, motivating the development and implementation of technologies such as liquid air energy storage (LAES). This study investigates the thermodynamic performance of LAES and evaluates the improvements attained through natural gas added firing (AF), determining the coefficients of structural bonds to identify design optimization priorities. Subsequently, LAES configurations are benchmarked against mid-scale natural gas combined cycles (NGCC) and batteries through an economic optimization based on electricity price profiles from different European markets for the year 2023. At a CO2 emissions tax of 100 /ton, results reveal that the LAES-AF concept located in Germany could compete with an NGCC plant if natural gas prices exceed 8.3 /GJ, while for prices above 9.1 /GJ batteries (with cost reduction projected to 2030) were the preferred option. In this range, the LAES-AF plant reduced fuel consumption by 24.0-27.2 % relative to the NGCC benchmark, which would reduce emissions when using natural gas or costs when using costlier carbonneutral fuels. The standalone LAES plant did not prove economically viable in any location, being outperformed by batteries and requiring a CO2 price above 300 /ton to compete with LAES-AF. As electricity price volatility keeps rising with growing wind and solar market shares, the economic attractiveness of LAES should improve as longer periods of near-zero electricity prices negate its lower round-trip efficiency and capitalize on its lower cost for energy storage. Therefore, further work on the development of innovative LAES cycles is recommended.