Never shy to put his money where his mouth is, Sir Richard Branson has committed himself to spending $3 billion to fight global warming. This represents all of the profits from his travel firms - Virgin Atlantic and Virgin Trains in Britain and Virgin Express in Europe and Virgin Blue in Australia - over the next 10 years.

"We must rapidly wean ourselves off our dependence on coal and fossil fuels," Branson said at the time of the announcement.

The money will be invested in schemes to develop new renewable energy technologies, through an investment unit called Virgin Fuels.

This business was launched in 2006 and is expected to invest $400 million in green energy projects. It has already backed a business in California called Cilion, which plans to make bio ethanol from corn.

Virgin Atlantic first took to the air in 1984, with Branson running services between London and New York. He entered the rail business in 1997 and owns 51 per cent of Virgin Trains, which operates two franchises between London and the south-east of England and London and Scotland.

Virgin Trains last year ran a six-month trial using biofuel to power its trains and said that its fleets could switch to using a mix of diesel and biofuel.

In the absence of a viable alternative fuel, Virgin Atlantic said that it was taking a number of practical measures to reduce the carbon footprint of its aircraft.

"We've been working hard to remove any extraneous weight from our aircraft," a spokeswoman said.