A novel coal chemical looping gasification scheme for synthetic natural gas with low energy consumption for CO2 capture: Modelling, parameters optimization, and performance analysis

Natural gas is regarded as a clean energy source, but its global supply is seriously insufficient. An alternative route to synthetic natural gas production from other energy sources is thus urgently needed. There is the conventional coal gasification to synthetic natural gas process, but it suffers from high energy consumption because of air separation and CO2 capture. Coal chemical looping gasification is regarded as a state-of-the-art technology that avoids conventional air separation and reduces energy consumption. A new process of coal chemical looping gasification that creates synthetic natural gas is therefore proposed, where low energy consumption for CO2 capture is achieved simultaneously by increasing the CO2 concentration. The results show that the exergy efficiency of the new process is increased by 21%; the internal rate of return is increased by 9%; the fixed capital investment and production costs are reduced by 36% and 29%; and the CO2 emissions are reduced by 15% in comparison with the conventional coal to synthetic natural gas process. This study provides a promising method for the energy-saving, profitable, and sustainable development of coal into synthetic natural gas.