In an editorial published in the latest edition of journal Science, London-based Dr Steven Koonin said biofuels are more energy-efficient than many experts had realised and were capable of supplying a big slice of global vehicle fuel demand.

“Credible studies show that with plausible technology developments, biofuels could supply some 30% global demand,” he wrote.

“To realise that goal, so-called advanced biofuels must be developed from dedicated energy crops, separately and distinctly from food.”

The same edition of Science also published a review of the energy efficiency of ethanol made from agricultural products such as corn, cane sugar and grain.

The review’s findings would surprise many – ethanol as it is currently produced is more energy efficient than at first thought, but its environmental benefits are modest

University of California, Berkeley energy resources expert Alexander Farrell and colleagues evaluated six major studies of ethanol, and found that it was 95% as energy efficient as petrol.

But Farrell concluded making ethanol using current technology was expensive and had its own environmental costs, which meant that ethanol cut greenhouse gas emissions by only 13%.

“[The environmental cost] comes from making fertiliser, running the tractors over the farm and operating the biorefinery,” Farrell said.

One environmentally sound way to produce ethanol would be to produce it from waste material. Farrell has suggested deriving the fuel from woody parts of plants, using what is known as cellulosic technology to break down the tough fibres.

But at the moment, this technology is expensive and big advances would have to be made for this to be cost-effective.

Writing in the same issue of Science, scientists from Imperial College London, Georgia Tech and Oak Ridge National Laboratory in Tennessee said they had teamed up to find ways to make a facility that would biomass to make fuels and other products with no part of the plant going to waste.

“We’re looking at a future for biomass where we use the entire plant and produce a range of different materials from it,” Imperial College researcher Dr Charlotte Williams said in a statement.

“Before we freeze in the dark, we must prepare to make the transition from non-renewable carbon resources to renewable bioresources.”

Even without such production facilities, the US, European Union and India expect that at least 5% of their road fuels with be biofuels within five years.

Australia has a non-binding target of 350 million litres of biofuels per year by 2010, less than 2% of the country's road fuel. However, the government has said it is confident that this target will be exceeded.