Carbon sequestration with enhanced gas recovery (CSEGR) for a novel natural gas value chain: Synergy with cold energy utilization

Liquefied natural gas (LNG) plays a primary role in long-distance transportation; however, its production is energy-intensive, and CO2 emissions from its use are unavoidable. To address these challenges, a liquid CO2-mixed refrigerant (LCO2MR) process is proposed, utilizing CO2 in two distinct ways: (i) recovering cold energy from LNG regasification for use in the natural gas liquefaction process and (ii) injecting CO2 into gas fields for enhanced gas recovery (EGR), boosting natural gas production. This study comprehensively analyzes the proposed process, focusing on thermodynamic, economic, and environmental impacts. The energy consumptions for the propane precooled mixed refrigerant (C3MR) and LCO2MR processes are 970 and 815 kJ/kg of LNG, respectively. The LCO2MR process has an annual expense 18.94 % lower than C3MR process when considering carbon tax, due to its simpler structure and lower energy requirements. Environmentally, the LCO2MR process reduces CO2 emissions by 53.33 % across the value chain compared to the C3MR process. Additionally, using CO2 for EGR is projected to increase natural gas production by 81.67 tons/h. These results indicate that utilizing CO2 as a cold energy carrier and for increasing natural gas production is energetically and economically advantageous, significantly reducing CO2 emissions and contributing to a cleaner LNG value chain.