Microbes can turn oil into gas
The research team, headed by Steve Larter, a petroleum geologist, carried out a series of experiments showing how oil-eating microbes can convert heavy oil into methane by a process of anaerobic fermentation in the absence of oxygen. It is this natural biodegradation of hydrocarbon deposits that produces natural gas fields.
Biodegradation of crude oil into heavy oil in petroleum reservoirs is a problem worldwide for the petroleum industry. The natural process makes what is called bitumen; viscous oil which contains contaminants and pollutants such as sulphur. This makes recovering and refining heavy oil difficult and costly.
Scientists believe that if the technique can be demonstrated to work on a large scale on underground deposits, it could lead to a massive increase in the availability of fossil fuel without a corresponding increase in greenhouse-gas emissions.
They estimate, for instance, that by ’fertilizing’ the populations of subterranean microbes that already exist in oil fields it may be possible to speed up the conversion of heavy oil to natural gas by many thousands of times, and possibly double the exploitable reserves of fossil fuel.
Oil sands companies would be able to recover only the clean-burning natural gas directly from deeply buried, oil sands deposits, leaving the hard-to-handle bitumen and contaminants deep underground.
The oil industry expends significant energy extracting heavy oil deposits such as tar-like bitumen, which has to be melted with superheated steam injected down boreholes. If such deposits could be broken down by microbes into methane, or natural gas, the extraction would be cleaner and more efficient, said Professor Steve Larter, of the University of Calgary in Canada. Per energy unit, methane is a much lower carbon dioxide emitter than bitumen.
The research team also discovered an intermediate step in the biodegradation process, which involves a separate family of microbes that produce carbon dioxide and hydrogen from partly degraded oil, prior to it being turned into methane.
This paves the way for using the microbes to capture this CO2 as methane, which could then be recycled as fuel in a closed-loop energy system. This would keep additional carbon dioxide out of the atmosphere.