Energy efficiency analysis of biomass-based synthetic natural gas production process using interconnected fluidized beds and fluidized bed methanation reactor

Biomass-based synthetic natural gas (Bio-SNG) has attracted extensive attention in recent years. In order to analyze the energy efficiency of Bio-SNG production system, a simulation model of this system via interconnected fluidized beds and fluidized bed methanation reactor is built and validated. Then, the influences of operating conditions and biomass categories on the energy efficiency are studied. The results show that the Bio-SNG production process can achieve energy efficiency higher than 64 %. There exists an appropriate gasification temperature (around 750 °C), gasification pressure (about 0.3 MPa), ratio of steam to biomass (ranging from 0.4 to 0.8), methanation temperature (around 350 °C), and pressure (around 0.3 MPa) to maximize the energy efficiency. With respect to the typical biomass, the highest energy efficiency is found in sawdust, while the lowest is in rice straw. After comparing with the hydrogen production and diesel oil production from biomass, the Bio-SNG production is more competitive in the energy efficiency.