Process and levelized cost assessment of high CO₂-content natural gas for LNG production using membrane and CFZ CO₂ separation integrated with CO₂ sequestration

The study compared the techno-economic performance of two CO₂ separation technologies from high CO₂-content natural gas, membrane and controlled freeze zone (CFZ) separation, for liquefied natural gas (LNG) production integrated CO₂ sequestration. Process and economic performances of both technologies are compared based on process simulation and levelized costs, respectively. The process simulation was performed by using Aspen Hysys V11 software. The process performance results show that the CFZ-based separation process gives CO₂ capture of 99.47% and hydrocarbon recovery of 95.40%. The results show better performance compared to the membrane-based with CO₂ capture of 95.78% and 92.92% of hydrocarbon recovery. The LNG production process with feed gas from CFZ required 431.92 kWh/tonne-LNG, which is also a better performance than with feed gas from the membrane of 453.93 kWh/ton-LNG. From an economic perspective, the total levelized cost of LNG production, without the CO₂ sequestration, is 10.27 US$/MMBtu for the CFZ-based and 8.95 US$/MMBtu for the membrane-based. Adding the CO₂ sequestration process raises the total levelized cost of LNG production to 14.67 US$/MMBtu (CFZ) and 13.12 US$/MMBtu (membrane). Therefore, the East Natuna gas field's development has challenges in cost associated with bulk CO₂ separation and sequestration to monetize the resources' potential.