( BBC ) - The first flight by a commercial airline to be powered partly by biofuels is to take off from London.
The Virgin Atlantic flight, to Amsterdam, will not have any passengers on board.
The airline says the flight is an important milestone in the development of greener fuels.
But many environmentalists say cultivating the fuel is not sustainable and will lead to deforestation and reduced land for food.
The Boeing 747 will have one of its four engines connected to an independent tank filled with biofuel.
This reduces risk to the flight because there are three other engines which can power the plane using conventional fuel if there is a problem.
Virgin has so far refused to say what biofuel is being used.
One problem with flying planes using biofuel is that it is more likely to freeze at high altitude.
The technology is still being manufactured by companies GE and Boeing, but Virgin believes within 10 years airlines could routinely be flying on plant power.
Kenneth Richter, biofuels campaigner at Friends of the Earth, said the flight was a "gimmick", distracting from real solutions to climate change.
"If you look at the latest scientific research it clearly shows biofuels do very little to reduce emissions. At the same time we are very concerned about the impact of the large scale increase in biofuel production on the environment and food prices worldwide," he said.
"What we need to do is stop this mad expansion of aviation at the moment it is the fastest growing source of greenhouse gases in the UK and we need to stop subsidising the industry."
Paul Charles of Virgin Atlantic says it would reveal the biofuel after the flight but it was one which did not compete with staple food resources.
"Some of us in the industry are doing something about reducing our carbon emissions, I don't think that's a gimmick - it's progress," he said.
"This is about progress and reducing carbon emissions and that should be welcomed."