Ann: AGM Presentation , page-12

Biogenic gas is produced by microbes in the earth's crust - they seem to be digesting a source of carbon and excreting methane. In the normal course of events this would gradually seep into the earth's atmosphere but we are intercepting it at depths of up to 2000m. Gold mines in RSA have been doing same for many years when it proved hazardous to thir mining operations.
So far we are able to tap into gas at a rate well below the microbe's production rate - the challenge will be not to over draw this resource but to extract at a rate equivalent to the natural recharge rate. This could amount to many millions of scf per day for a very, very long time.