According to Luca, the biogenic creation of methane from a higher molecular weight hydrocarbon source is a multi-step process, most likely accomplished by a consortium of anaerobic microbes acting together in a symbiotic fashion. Through a series of steps, various organisms in the consortium breakdown the large hydrocarbon molecules in coal or oil into intermediate, water-soluble compounds, which are then reduced to even smaller hydrocarbon molecules, and finally metabolized into methane by a group of organisms known as methanogens.

Luca has termed these areas where biogenic methane formation occurs Geobioreactors.

There’s an interesting twist to this. In order for a Geobioreactor to function, according to Luca, the appropriate environmental conditions must be present, including an abundant hydrocarbon substrate (such as a coal bed), a water-saturated environment, a complete absence of free oxygen (the microbes are anaerobes), and the presence of the correct consortia of organisms.

However, conventional techniques for extracting existing coalbed methane involve pumping groundwater out of the coal beds to enable recovery of the gas sequestered within them. An unforeseen consequence of this pumping is the influx of air, which contains abundant free oxygen that is toxic to the methane-producing microorganisms. The practice also removes water, damaging the microorganisms. In other words—assuming Luca’s scenario is correct—the extraction of coalbed methane destroys the mechanism for producing more methane.

There is much to do to confirm and to leverage this discovery. Luca is working to engineer methods for optimizing the natural gas-producing activity of natural Geobioreactors it identifies, as well as methods of turning other energy resources—such as oil wells that are no longer actively producing—into efficiently functioning Geobioreactors.

Background Paper: Active Biogenesis of Methane in Wyoming’s Powder River Basin