Abandoned energy

Researchers from Newcastle University and Calgary University in Canada think they may have found a way of extracting more energy from the world's oil reserves.

The team of geologists and biologists have been studying the little-understood process by which naturally-occurring bacteria deep below the ground convert oil and coal to natural gas over many millions of years.

They believe that the process could be speeded up, possibly by simply feeding the bacteria nutrients like vitamins and minerals down boreholes.

If the theory works in practice, oil and possibly coal reserves that are currently uneconomic to extract from the ground could be converted to sources of natural gas, otherwise known as methane.

The research was led by Prof Ian Head and Dr Martin Jones, of Newcastle University, and Prof Steve Larter, who works at both Newcastle University and Calgary University in Canada.

It was already known that most of the world's oil reserves are affected by the bacteria, to some extent. This reduces the value of the oil by making it thicker and more costly to extract. Some reserves have been left in the ground because it would be uneconomic to work them.