Unlocking the potential of solar heating for liquid air energy storage: Multi-regional techno-economic insights

This paper proposes a novel solar-integrated Liquid Air Energy Storage system (termed LAES-Solar) that addresses the efficiency-cost trade-off associated with compression configuration and thermal energy storage in conventional LAES systems. The proposed system employs a multi-stage compression configuration during the charging process, with the associated compression heat recovered and directly utilised for domestic heating. This configuration minimises liquefaction energy consumption while reducing capital expenditure associated with both the liquefaction process and thermal energy storage. During discharging, solar thermal energy from parabolic trough collectors is used to superheat the air, thereby enhancing power generation performance. Thermodynamic analyses of the proposed system show a round-trip efficiency (RTE) of 74.26% and a combined heat and power (CHP) efficiency of 136.07% when solar heat input is considered free. These represent improvements of 57% and 66%, respectively, compared to a standalone Liquid Air Energy Storage (LAES) system. To support the deployment of solar-assisted LAES in different geographical regions, a multi-regional solar-field design and operation framework is developed and applied to a 50 MW/400 MWh LAES-Solar system. Three solar field design strategies, peak-month, annual-average, and full-load, are systematically evaluated to demonstrate how optimal solar-field sizing and operation depend on regional solar resources and electricity market conditions. Case studies were conducted using data from three representative locations, Golmud and Turpan (China), and Almería (Spain). The results show that Almería achieves the shortest dynamic payback period (DPP) of 9.31 years with the full-load solar design strategy, primarily due to higher local energy prices. With potential future cost reduction in solar thermal technologies, significant economic performance improvement is found possible, for example, the DPP in Almería could be reduced to 4.59 years. Alternative solar thermal technologies, including parabolic dish and solar tower power, were also explored, with a solar heat supply temperature up to 1000 °C. The results demonstrate superior efficiency enhancement compared with standalone LAES system, highlighting solar integration as a promising approach to enhance both LAES efficiency and cost-effectiveness.