A novel liquid air energy storage system with efficient thermal storage: Comprehensive evaluation of optimal configuration

Liquid air energy storage (LAES) stands out as a highly promising solution for large-scale energy storage, offering advantages such as geographical flexibility and high energy density. However, the technology faces challenges inherent in the cold and heat storage processes. While systems with liquid-phase medium can offer high efficiency, it comes with drawbacks including environmental pollution, safety concerns, and high costs. Alternatively, systems with solid-phase media in packed beds can address these issues, yet it profoundly weakens system performance. Compounding these issues, many current economic evaluations of LAES rely on inaccurate or outdated data, resulting in skewed assessments. In response to these challenges and to drive scientific evaluation and engineering advancements in LAES, this study introduces an innovative LAES system with efficient thermal storage (ETS-LAES). An original thermal storage method is introduced for the first time, based on gravity-driven solid-phase particle flow and gas-solid direct contact heat transfer. The study establishes thermodynamic and heat transfer models, along with a universally applicable economic evaluation model. The ETS-LAES system is comprehensively assessed utilizing different operational modes introduced in the study. Research findings showcase a round-trip efficiency (RTE) of 58.76%, currently standing as the highest RTE record for cold and heat storage based on solid-phase media. The economic evaluation reveals substantial advantages for the ETS-LAES system during the transition from demonstration projects to commercial projects and guides the selection of the scale for the LAES system. The levelized cost of storage (LCOS) for the ETS-LAES system can decrease to 0.0982 USD/kWh as the capacity increases to 1000MW, due to the use of inexpensive solid-phase thermal storage media throughout. The investment payback period (IPP) is halved compared to conventional LAES systems, indicating a strengthening of the profitability. The proposed solution in this study holds great potential, particularly in offering valuable insights into the practical implementation and commercialization of LAES.