Coal seam gas – our next renewable energy source?
CSIRO scientists are investigating whether injecting coal seams with certain kinds of bacteria and carbon dioxide can produce commercially viable quantities of natural gas.
Australia is blessed with large volumes of natural gas – enough to last centuries at current consumption rates. One of the biggest sources of natural gas comes from underground coal seams. This is often referred to as coal seam gas (CSG).
CSG can be either biogenic or thermogenic. Biogenic natural gas occurs as a product of microorganisms under the surface of the earth, whereas thermogenic natural gas results from chemical reactions that occur without the presence of microorganisms. These decomposition reactions are instead triggered by the application of extreme heat.
Most, but not all CSG is thermogenic. Researchers are now interested in the nature of biogenic CSG, and how it can be enhanced. The challenge is to find a way to encourage the microbes to produce more methane or natural gas to either replace gas reserves that have been used, or to supplement existing reserves.
The CSIRO is currently developing a program on microbial enhancement of coal seam gas production. This is aimed at understanding the processes involved and finding ways to replenish depleted and unproductive coal seams.
The trick is to find and supply nutrients to the right microbes, which occur naturally in the environment, to produce methane.
In effect, these microbes produce methane as they grow and live, much as we produce carbon dioxide when we breath.
These ‘bugs’ can feed on carbon dioxide , converting it to usable methane, and on buried coals or special food injected underground to stimulate the gas production.
These processes are already going on naturally, and scientists are looking for ways to exploit this activity. The result could be an important new source of renewable energy.
CSG: potentially the next renewable energy source!