Many people that I have spoken with say they donâ€™t know much about it, so Iâ€™ll start with a short description from Wikipedia.
â€œCoalbed methane is a form of natural gas extracted from coal beds. In recent decades it has become an important source of energy in the United States, Canada, and other countries. Australia has rich deposits where it is known as coal seam methane. Also called coalbed gas, the term refers to methane adsorbed into the solid matrix of the coal. It is called â€™sweet gasâ€™ because of its lack of hydrogen sulfide. The presence of this gas is well known from its occurrence in underground coal mining, where it presents a serious safety risk.â€
That sounds simple enough, but what happens when you try to get it to the surface? It would appear that CBM extraction is not as nasty as some other ways of using energy from coal beds. However, there are still some environmental considerations. There always are.
From Wikipedia again: â€œCBM wells are connected by a network of roads, pipelines, and compressor stations. These structures can compromise the scenic quality of the landscape, fragment wildlife habitat, and displace local wildlife populations. Over time, wells may be spaced more closely in order to extract the remaining methane. Additionally, the produced water may contain undesirable concentrations of dissolved substances. Water withdrawal may depress aquifers over a large area and affect groundwater flows.â€
Ah yes, water. It seems that there is always something about water. CBM extraction is basicly accomplished by pumping water out of the coal seam, so it is clear that there is a potential for disturbing water supplies, at least indirectly. But what happens with the waste water?
This contaminated water is called â€œproduced waterâ€ by the industry. Disposal of this wastewater can have disastrous consequences for agricultural land, drinking water supply, and fish and wildlife. The problems vary from area to area and with the engineering solutions chosen, but it is certainly something which is worth keeping an eye on.
This article goes on to discuss topics like Underground Coal Seam fires that can start after the dewatered coalbeds are exposed to Oxygen. Click the link below to read more.