Energy consumption and greenhouse gas emissions of shale gas chemical looping reforming process integrated with coal gasification for methanol production

Abstract

Abstract More than 65% methanol in China is produced by a coal-to-methanol route, which suffers from low carbon utilization, high energy consumption, and serious CO2 emission. On the other side, shale gas chemical looping reforming is an efficient syngas production technology, but its hydrogen content is much higher than the requirement of methanol production. Therefore, this study proposes a novel high-efficient methanol production process integrating coal gasification and shale gas chemical looping reforming & combustion via systems engineering method. At the cost of additional shale gas consumption of 0.485 t/t, the coal consumption of the novel process is reduced from 1.45 t/t to 0.20 t/t, which leads to the high exergy efficiency of 71.04% achieved in the novel process. From the aspect of life cycle, the abiotic depletion fossil consumption of the novel process is reduced to 37.2 GJ/t (41.8% lower than that of the coal-to-methanol process) due to the mass and energy integration between coal gasification and chemical looping units. The impact ratios of the novel process/coal-to-methanol are 0.35, 0.39, 0.53, and 0.59 for the global warming potential, acidification potential, eutrophication potential, and photochem ozone creation potential, respectively. It is concluded that the above coupling process has significant application prospects in improving mass-energy utilization efficiency and reducing air pollutant emissions of the coal-based methanol production process.