It was last updated at 12:25 on April 28 2008. The US air force will this week call for the world's top scientists to come together in a 21st-century Apollo-style programme to develop greener fuels and tackle global warming. It wants universities, governments, companies and environmental groups to collaborate on a multibillion-dollar effort to work out greenhouse gas emissions of existing and future fuels. William Anderson, an assistant secretary of the air force, said the project aimed to calculate the overall carbon footprint of the world's energy sources, rather than merely measure their direct emissions.

He said controversy over the environmental impact of biofuels showed such an effort was needed to avoid making the situation worse: "If you look at the situation with bioethanol from corn, a lot of people saw that as a panacea, but now it seems that if you include the lifecycle greenhouse gas emissions, the carbon footprint may be worse than people realised. "If the world wants to get serious on greenhouse gas emissions, we have to figure out where they're coming from."

Anderson said the effort required was the modern equivalent of the Apollo missions to put a man on the moon, "and the US air force knows something about that". The project will be discussed on Wednesday at a meeting in Washington DC organised by the Connecticut Centre for Advanced Technology. Anderson said the project aimed to combine research already under way across the world, and to encourage governments and companies to release "billions of dollars" of funds.

US officials have already met the Royal Air Force and French air force to discuss ways to make their activities more environmentally friendly. A second meeting is scheduled for Paris in June. Anderson said the military could learn from civilian airlines, which have studied how to reduce weight and increase fuel efficiency. He said: "What everybody sees is the fighter aircraft, but the predominant part of what we do is transporting people and stuff around. And so do British Airways, so do Virgin and so do Fed Ex."

Concerned about future supplies of oil, the US air force plans to switch its aircraft to a synthetic liquid fuel made from coal. It has tested the new fuel in aircraft such as the B-52 bomber, and is encouraging the British and French to follow. Anderson said: "Energy demand is going to outstrip any gains from renewables. As oil starts to diminish, coal is going to play big."

Environmental campaigners have criticised such fuels, which they say have overall carbon emissions about double those from oil. But Anderson said much of the carbon pollution could be trapped and stored underground. He insisted the air force would not switch to new technology unless it "has a greener carbon footprint" than existing fuels.

(Por David Adam, The Guardian, 28/04/2008)