A novel integrated system of hydrogen liquefaction process and liquid air energy storage (LAES): Energy, exergy, and economic analysis

Abstract

With the global positive response to environmental issues, cleaner energy will attract widespread attention. To improve the flexible consumption capacity of renewable energy and consider the urgent need to optimize the energy consumption and cost of the hydrogen liquefaction process, a novel system integrating the hydrogen liquefaction process and liquid air energy storage (HLP–LAES) is proposed. The operating strategy of the system ensures that it can produce liquid hydrogen and has the function of energy storage and power generation. A 3E study (energy, exergy, and economics) is carried out to evaluate the techno-economic performance of the proposed energy-intensive process. After optimization of key parameters, when the daily output of liquid hydrogen is 50 tons, the maximum daily power generation can reach 131.3 MWh, accounting for 1.21% of the daily electricity consumption of urban and rural residents in Qinghai Province, China. The round-trip efficiency of the proposed process is 58.9%, the specific energy consumption of liquid hydrogen is 7.25 kWh/kgLH2, and the total exergy efficiency is 53.2%. The payback period will be reduced to 1.7 years when the liquid hydrogen is sold at 7.0 $/kgLH2. If the proposed process is retrofitted from a stand-alone hydrogen liquefaction plant, the shortest retrofitting payback period is 9.2 years. The charging and discharging processes of the LAES are innovatively redesigned to better match the hydrogen liquefaction process, while achieving deep coupling and good synergy between the systems. This work aims to provide a reference for the efficient consumption of renewable energy, grid load balancing, and commercialization of the combination of liquid air energy storage and hydrogen liquefaction plants.