Fuelled by compost bugs

Simon Gompertz
Working Lunch

Could your car run on compost?

It's not every day you look in a compost heap and find a bug which might help save the planet.

But a UK company is using just such a bug to make renewable fuel for cars.

Viewed through a microscope at TMO Renewables near Guildford in Surrey, hundreds of the new bacteria can be seen on the move.

Each is little more than 2% of the thickness of a human hair. But they have a potential which could be of enormous significance.

They turn rubbish into ethanol. And the bug, called TM242, licks its lips at a wide range of unappetising titbits, from rotten food to waste paper, grass and all sorts of leftovers from agriculture and industry.

Bug Brewery

TM242 is hungry for your rubbish.

"It's a mini-brewery. We are basically brewing beer," chief executive Hamish Curran told me as he showed off the TMO lab. From the beer, TMO extracts ethanol.

Back in the compost heap, TM242 would normally produce lactic acid. But the company has modified the inner workings of the bacterium so that when it eats complex carbohydrates, the by-product is ethanol instead.

"This bug has the ability to eat the material very quickly," adds Hamish Curran,"And it does it in a very energy-efficient fashion."

A little heating is needed, then it maintains its own operating temperature. This is a big deal for ethanol producers, because traditional yeast-based methods involve more heating throughout the brewing process.

Ethanol is a green alternative

Ethanol has been pushed as a climate-friendly substitute for petrol and an alternative to depending on unstable oil producing countries. In theory, using ethanol in vehicles reduces CO2 emissions, because CO2 has been absorbed by the plant used as a raw material, as it grows.

Hamish believes his big market will be the United States, where ethanol producers have a serious image problem.

The US has 200 ethanol factories using corn or maize as a feedstock. But environmentalists have attacked corn-based ethanol as a waste of money, energy and food.

TMO argues that its bug could give a new green tinge to America's ethanol producers: less energy needed, lower costs and more output.

Even the used corn pulp can be recycled to make more ethanol, by deploying TM242.