Methane Production from Biomass by Thermochemical Conversion: A Review

Methane, the main component of natural gas, is one of the primary sources of energy extensively employed worldwide. However, the utilization of natural gas is limited by reserves and geographical availability. Thus, a thermochemical method of converting biomass to methane is appealing, especially gasification. Important factors affecting methane production are discussed in the review including operating parameters, catalysts of methanation and gas conditioning effects. Low temperature and high pressure are beneficial to promote methanation reaction. Ni-based catalysts are widely used as methanation catalysts, but suffer from deactivation problems due to carbon deposition, sintering and poisoning. The methods of gas conditioning include using water gas shift reaction and adding hydrogen from electrolysis. In addition, environmental and economic views are discussed. Other thermochemical process including hydrothermal gasification, fast pyrolysis and direct methanation at low temperature are also introduced briefly. Based on the above discussion, potential research directions for optimizing methane production are proposed.