Thermodynamic analysis of an air liquid energy storage system coupling Rankine cycle and methane steam reforming to improve system electrical conversion and energy efficiency

Abstract

To solve the problem of the low electro-electric conversion efficiency of air liquid energy storage (LAES) systems and the low energy and exergy efficiency of LAES coupled with solar energy, a LAES system coupled with Rankine cycle and steam methane reforming system has been proposed. The system utilizes solar energy and couples the Rankine cycle to enhance power generation. The coupled steam methane reforming subsystem utilizes low temperature heat that is unavailable from the Rankine cycle for methane reforming to produce efficient fuel hydrogen. The article established the LAES and Rankine thermodynamic models, the economic model, and the solar heat flow test device for analytical studies. The findings indicate that the coupled system attains a staggered energy utilization, exhibiting a notably high exergy efficiency of 59.63%. This represents a marked enhancement of 15.45% when compared to the LAES system coupled with solar energy. The proposed system boasts an electro-electric conversion efficiency of 140.24%, demonstrating a remarkable 71.43% enhancement over the LAES-alone system. Moreover, the 1 MW system can produce up to 522.11 kg/h of hydrogen, the static payback period of the system is 6.12 years and the internal rate of return of the system can be 23.28%.