Simulation and Environmental Sustainability Assessment of an Integrated LNG-Power Cycle-Electrolyzer-Methanol Process for Clean Energy Generation

The growing demand for clean energy and sustainable industrial processes has driven interest in integrated energy systems that optimize resource utilization while minimizing environmental impacts. This study presents the simulation and environmental sustainability assessment of an integrated process combining liquefied natural gas (LNG), Allam–Fetvedt cycle, solid oxide electrolysis’ system, and methanol synthesis to produce clean energy. The proposed system enhances overall efficiency and sustainability by utilizing the Allam–Fetvedt cycle to generate power while capturing CO2, which is then used in the manufacture of syngas and hydrogen by the electrolysis of water and CO2. Syngas is subsequently transformed into methanol, a viable alternative fuel characterized by lowcarbon emissions. A comprehensive process simulation is conducted to evaluate energy efficiency, material flows, and system performance. The sustainability assessment focuses on environmental impact indicators, including carbon footprint reduction, energy efficiency improvements, and resource optimization. The results demonstrate that the integrated system significantly reduces CO2 emissions while maximizing energy recovery, making it a promising approach for decarbonized energy production. In this study, the integrated process including the ASU, power cycle, electrolyzers, methanol production units, and LNG unit results in carbon emissions of 0.29 kg CO2 per kg of LNG produced, which is very close to the literature-reported lower limit, even though it also has methanol production. On the other hand, when the identical process is assessed solely for methanol production (without the LNG unit), it attains net-zero carbon emissions. Despite the incorporation of high-energy electrolyzer systems, the overall energy demand of the proposed integrated process remains comparable to that of existing conventional technologies with high emission outputs.