The first commercial aircraft powered partially by biofuel completed a test run from London to Amsterdam, but scientists are conflicted on the environmental implications.
The jumbo jet belongs to Virgin Atlantic, the airline of flamboyant British entrepreneur Richard Branson.
Branson said that the flight was a first step towards reducing carbon emissions of aircraft.
"This breakthrough will help Virgin Atlantic to fly its planes using clean fuel sooner than expected," Branson said Sunday before the Boeing 747 flew from London's Heathrow Airport to Amsterdam's Schiphol Airport.
He said the flight would provide "crucial knowledge that we can use to dramatically reduce our carbon footprint."
The aircraft's engines were not modified and were fueled with a biofuel mixture of coconut and babassu oil in one of the four main fuel tanks. Virgin Atlantic claims the oils don't compete with staple food sources.
The jet carried pilots and several technicians, but no passengers. It lifted off at 11:30 a.m. local time on Sunday and touched down in Amsterdam about two hours later.
Not all agree
While some have seen the test flight as potentially useful, others have criticized it as a Branson publicity stunt.
The test also comes as more questions are being raised about the environmental benefits of biofuels.
"If Virgin would power its entire fleet with biofuel, it would have to use about half of the U.K.'s arable land," said Jos Dings, the director of the European Federation for Transport and Environment.
Scientists are conflicted over whether biofuel is actually more climate-friendly than traditional fuels, when its production emissions are factored in.
"It's great that somebody like Richard is willing to put some of his billions into an experiment aimed at reducing the climate change impact of aviation," said James Halstead, an airline analyst at the London stockbroker Dawnay Lochart.
"But there are a lot of unanswered questions about the usefulness of biofuels in the battle against global warming."
Virgin Atlantic claims the analysis of data collected during the test flight will take weeks to complete.
Air travel forms a relatively small but growing part of carbon emissions. Environmental advocates have said that a jet trip from Canada to Europe releases as much carbon as driving a car for a year.
The European Union has said that air travel accounts for about three per cent of EU carbon emissions but have grown by 87 per cent since 1990.
The experiment by Virgin Atlantic and its partners -- Boeing, General Electric and Imperium Renewables -- is the latest example of how the world's airlines are trying to find ways of reducing aviation's carbon footprint.
These efforts have included finding alternative jet fuels, developing engines that burn existing fuels more slowly, and changing the way planes land.
Air New Zealand, the Rolls-Royce Group and Boeing plan to conduct a test flight of a Boeing 747 next year that will partly run on biofuel.
With files from The Associated Press
