Exergy and pinch assessment of an innovative liquid air energy storage configuration based on wind renewable energy with net-zero carbon emissions

Abstract

Given the rising global energy demands and the fluctuating nature of load demand, advancing various energy storage systems to enhance their efficiency is essential. Moreover, the increase in greenhouse gas emissions from various industries has prompted governments to implement carbon dioxide (CO₂) capture systems and invest in renewable energy sources. In this research, a cryogenic energy storage configuration is developed according to the air liquefaction process, liquefied natural gas (LNG) regasification operation, CO₂ capture cycle, and organic Rankine plant. During off-peak times, the air entering the energy storage system is compressed and liquefied using wind energy and the cold energy from LNG vaporization, producing 83.12 kg/s of liquid air. During on-peak times, the liquid air and LNG after recovering the cold energy enter the power generation cycle, generating 119 MW of electrical power. This power generation cycle includes a combustion chamber, gas turbine power plant, and organic Rankine cycles. Flue gases from the power generation cycles enter the amine-based CO₂ capture and then the output CO₂ is stored in liquid form. The storage and round-trip efficiencies of the present energy storage configuration are 67.97 % and 62.50 %, respectively. The results of exergy analysis show that the exergy efficiency of the whole system, off-peak, and on-peak sections are calculated as 64.88 %, 82.40 %, and 74.03 %, respectively. The pinch method for multi-stream exchangers (HX6, HX7, and HX8) is accomplished and the exchanger network related to each one is determined. Three-dimensional sensitivity analysis indicates that storage and round-trip efficiencies increase up to 80.45 % and 66.20 %, respectively when the power generation section pressure increases up to 110 bar and compressed air pressure decreases to 135 bar.