A novel liquid air energy storage system integrated with a cascaded latent heat cold thermal energy storage

Liquid air energy storage system (LAES) is a promising Carnot battery's configuration that includes thermal energy storage systems to thermally connect the charge and discharge phases. Among them, the high grade cold storage (HGCS) is of paramount importance due to the waste cold recovery of the liquid air regasification process. As of now, most of the literature studies on LAES designed to store the cryogenic energy using sensible heat material and only few works (including one recently carried out by the authors) proposed the implementation of phase change materials (PCMs) as alternative promising solution. This paper goes a step further numerically investigating a novel configuration of the HGCS system utilizing a cascade of multiple PCMs in place of the single PCM HGCS. By enhancing the thermal buffer effect typical of PCM media, the cascaded HGCS augments both the capacity ratio of the charge phase (0.87 vs 0.81) and the utilization factor of the discharge phase (0.87% vs 0.80%). As a result, the novel LAES system based on cascaded PCMs is capable to achieve a liquefaction specific consumption of 0.27 kWhe/kgLA, increasing thus the liquefaction performance of the single PCM HGCS by 6%.