Cogeneration plants can be powered by gas recovered during oil extraction and coal processing.
In the first case, these are gas naturally present in oil wells. Gas is predominantly composed by methane, which is also known as “associated oil gas” or “APG” which is in liquid form when is mixed with oil, and become gaseous as it approaches the surface.
In the second case, it is predominantly methane gas produced during coal mining. It is extracted from the mine to make mining operation safer and prevent uncontrolled leaks into the atmosphere. Mining is, in fact consistently exposed to gas explosion risks.