Microbial enhancing coal-bed methane generation potential, constraints and mechanism - A mini-review

Microbial enhancing coal-bed methane generation (MECMG) is a feasible and environment-friendly approach for improving coal-bed methane production. In order to understand the potential of biogenic methane generation and factors controlling the process, the biogenic methane yield, coal intrinsic characteristics and incubation conditions are assembled from the published data. Results show that sub-bituminous and high volatile C-B bituminous coal have higher biogenic methane generation yield than that in peat and anthracite. Contents of H, N, and volatile matter in the coal contribute positively to the biogenic methane generation yield. The optimized conditions for ex-situ biogenic methane generation are headspace gas type, culture temperature, particle size, solid-liquid ratio and pH of N2:CO2 (4:1 v/v), 28-30 °C, 60 μm, 1:10, and 7.0-7.5, respectively. The organic composition and molecular structure collected from coal-bed produced water, culture solution, and biodegraded residuals would provide effective evidences for revealing biogenic methane generation mechanisms.