Cheaper natural gas from oilfields

some microbes have been breaking down petroleum into methane deep within the earth for ages. But we do not know the bacteria or how they do it. A recent study has revealed the answers, with scientists producing methane from petroleum in the laboratory by feeding these microbes.

Over millions of years, some bacteria have adapted to conditions deep below the soil, deriving their energy by consuming the oil. In turn, they lace the petroleum with impurities like sulphur, thereby making it unusable without refining. "This biodegradation of crude oil ... has affected the majority of the world's oil, making recovery of the purified oil costly,' said a paper published in the online edition of the journal Nature on December 12, 2007. The end result of the breakdown is methane.

"In a typical petroleum reservoir, you can extract 35 per cent of the oil, with 65 per cent remaining unextracted,' said microbial ecologist I M Head of the University of Newcastle in the uk, one of the authors. "The equivalent figure for gas is 70 per cent and 30 per cent. If we can convert oil into methane, then the recovery of energy goes up.'

A gas revolution Understanding how crude oil biodegrades into methane opens the possibility of recovering the clean-burning natural gas directly from deep oil sand deposits. This could eliminate costly