The Scotsman reports that Sir Richard Branson yesterday announced plans to power his planes on plant waste as a greener alternative to conventional aircraft fuel.

The Virgin Atlantic chairman said he was considering opening refineries to produce cellulosic ethanol, which he claimed could replace kerosene.

However, the move surprised environmental campaigners, who said studies had shown ethanol was unsuitable as aircraft fuel, and no viable alternatives were on the horizon.

Sir Richard said: "We are going to start building cellulosic ethanol plants to make fuel that is derived from the waste product of the plant. It is 100 per cent environmentally-friendly and I believe it‘‘s the future of fuel.

"Over the next 20 or 30 years, I think it actually will replace the conventional fuel that you get out of the ground." Sir Richard said cellulosic ethanol differed from ethanol, which came from corn or fruit.

Richard Dyer, a campaigner for Friends of the Earth, said research had concluded that nothing would replace kerosene for several decades.

But Norman Baker, the Liberal Democrats‘‘ Westminster environment spokesman, said: "It is very important we maximise technology to minimise the impact of aviation on the environment. I welcome any steps taken to move in this direction."