Feasibility of microbial production of new natural gas from non-gas-producing lignite

• Stimulated microbial methane generation from non-producing coals.
• Differences in microbial response to treatments based on methane generation amount.
• Indicated regional differences in microbial growth based on molecular analyses.

This work reported real-time generation of microbial natural gas (methane) from lignite. Lignite (brown coal) samples and formation water were collected from locations in Australia, Indonesia, and China with no history of natural gas production (zero gas baseline). These samples were set up in microcosms and stimulated for new gas production by amending with essential nutrients. Results show that the Indonesian lignite yielded the highest methane production rate along with the highest enumeration of total bacteria and methanogens. The Australian lignite also produced methane that was associated with a decrease in CO2 composition. The Chinese lignite generated methane, but showed a decrease in methanogen counts, presumably due to microbial community shift. Overall, the results from this preliminary study indicate that application of nutrients to lignite can realize real-time methane production. Further molecular biology analysis is required to determine the constitution and shift in microbial populations during the process of methane generation from lignite.