Simulated process evaluation of synthetic natural gas production based on biomass gasifcation and potential of CO2 capture using membrane separation technology

Abstract

Synthetic natural gas (SNG) production using biomass gasifcation has recently become important as SNG has been suggested as an alternative to fossil fuels. In the process, CH4 synthesis (methanation) must be considered in addition to biomass gasifcation. By integrating exothermic methanation and endothermic gasifcation, the required heat energy can be lowered in an autothermal process. In this study, the performances of autothermal SNG production were estimated from process simulations. In this process, CO 2 separation after methanation is inevitably energy-intensive. Therefore, feasibility analysis was conducted on the autothermal SNG production process with CO2/CH4 membrane separation, which is expected to achieve drastically lower energy consumption. These assessments can determine whether membrane separation has the potential as an alternative to the conventional separation unit. Using a membrane process, CH4 loss can become less than 2 %, if the separation factor of CO2 over CH 4 exceeds 50. Therefore, we conclude that this value should be set as the minimal target value for the CO2/CH4 separation factor. Achievement of this goal will probably facilitate widespread use of SNG production by biomass gasifcation.