The first flight by a commercial airline to be powered partly by biofuel has taken place
A Virgin Atlantic jumbo jet has flown between London's Heathrow and Amsterdam using fuel derived from a mixture of Brazilian babassu nuts and coconuts.
Environmentalists have branded the flight a publicity stunt and claim biofuel cultivation is not sustainable.
Earlier this month, Airbus tested another alternative fuel - a synthetic mix of gas-to-liquid.
Virgin boss Sir Richard Branson said the flight marked a "vital breakthrough" for the entire airline industry.
"This pioneering flight will enable those of us who are serious about reducing our carbon emissions to go on developing the fuels of the future," he said.
But he said fully commercial biofuel flights were likely to use feedstocks such as algae rather than the mix used on the passenger-less flight.
Virgin's Boeing 747 had one of its four engines connected to an independent biofuel tank that it said could provide 20% of the engine's power.