Liquid Air Energy Storage: Analysis and Prospects

Energy supply is an essential factor for a country’s development and economic growth. Currently, our energy system is dominated by fossil fuels that produce greenhouse gases. Thus, it is necessary to switch to renewable energy forms and increase efforts in waste-to-energy systems. However, once renewable energy sources are introduced in the industrial system, the most important considerations are stability and sustainability of the energy supply because of the intermittency of renewable energy. Based on the previous considerations, storage technologies for electrical energy are discussed to compensate for this problem. A few mature technologies are introduced, such as pumped hydroelectric energy storage (PHES), compressed air energy storage (CAES), H2 energy storage and batteries. However, they have not been widely applied due to some limitations such as geographical constraints, high capital costs and low system efficiencies. Liquid air energy storage (LAES) has the potential to overcome the drawbacks of the previous technologies and can integrate well with existing equipment and power systems. In this chapter, the principle of LAES is analysed, and four LAES technologies with different liquefaction processes are compared. Four evaluation parameters are used: round-trip efficiency, specific energy consumption, liquid yield and exergy efficiency. Capacity and response time are also essential properties. The results indicate that LAES with hot and cold energy storage has considerable advantages over the other processes. Finally, the prospects of a hybrid system with higher system efficiency and performance, where LAES is integrated with renewable energy, waste heat and batteries are discussed.