LONDON, England -- Last Sunday a Virgin Atlantic Boeing 747, fueled partly by biofuel, touched down in Amsterdam.
Sir Richard Branson hailed the test "a biofuel breakthrough for the whole airline industry."
Speaking to CNN following the demonstration flight, Sir Richard Branson, the chairman of Virgin Atlantic, was jubilant. Just one year ago, flying biofuels at 30,000 feet was deemed impossible. But Virgin had nailed it, proving -- surely -- that technology is developing fast and the airline is serious about reducing carbon emissions.
Environmental groups were not so sure. Friends of the Earth derided the test as a publicity stunt. Large-scale production of biofuel, it pointed out, is leading to rainforest destruction, rising food prices and human rights violations.
Studies also suggest that converting land for crops, such as palm oil used for biofuel, can generate far more in carbon emissions than the savings delivered by the fuel.
But Virgin Atlantic has been eager to stress that its biofuel does not cause deforestation or compete with food supplies. The fuel being tested used a 20 percent mix of biofuel made from babassu oil and coconut oil. Babassu nuts and coconuts are harvested from the floor of existing and mature plantations. Babassu oil is found in everyday cosmetic products and coconut oil is used in oil for biodiesel.
Virgin concedes that, while babassu and coconut oil could potentially fuel a small fleet of aircraft, it is not a realistic fuel source for aircraft globally.
As Paul Charles, director of corporate communications at Virgin Atlantic says, this is not a "long-term solution", rather "the first stage on the journey through to biofuels for aviation."
The aim of the test -- conducted with partners Boeing, GE Aviation and Imperium Renewables -- was to prove aircraft could run on biofuels, that the fuel doesn't freeze at 30,000 feet and that it can work in a normal jet engine without having to make modifications to the aircraft or its engines.
Going forward, Virgin Atlantic and Boeing will test biofuel made from algae that is farmed on non-productive land in ponds of seawater.
Actual yields of algae are unclear. Assuming 10,000 gallons of algae can be grown per acre every year, Boeing says the world's fleet could be powered by algae grown in an area the size of West Virginia. Other reports suggest the land required may be four times that.
But early tests for algae look promising, says a Boeing spokesperson. Fuel derived from algae oil has a lifecycle CO2 advantage, he says, which means it absorbs CO2 when the feedstock is being grown. It may also produce fewer particulates or other non-CO2 emissions when used in an engine compared to conventional petroleum-based fuel.
"Our future work will provide more conclusive benefits as these fuels are developed for commercialization," he says.
PR hype or not, research such as this is part of a growing body of work by the industry to reduce its impact on the environment.
The International Air Transport Association (IATA) last year set itself a long-term, yet ambitious, goal to build a zero emissions aircraft in the next 50 years.
Aircraft and engine designers are investing in fuel efficient aircraft. Airbus' A380 superjumbo and Boeing's upcoming 787 Dreamliner both use new engine designs, lightweight composite materials and advances in aerodynamics to improve performance, increase fuel efficiency and lower emissions.
Boeing is planning another biofuel demonstration flight later this year with Air New Zealand.
And earlier this month, Airbus, in association with Shell, Rolls Royce and Qatar Airways, began a research project to test 'Gas to Liquid' (GTL) technologies that convert lower-emission natural gas and other synthetic fuels into liquid kerosene.
In the short-term, GTL could become a "drop-in" replacement for oil-derived kerosene in aero engines and airports without requiring any modifications to equipment, says Airbus. It could offer improvements in local air quality, fuel economy and reductions in carbon dioxide and other emissions.
"We should start to see airlines using this sort of fuel in a couple of years' time with a mix of kerosene," he told CNN. "There are estimates that suggest that by 2025 we might see about 25 percent of aviation fuel coming from an alternate source."
Kenneth Richter, Friends of the Earth biofuels campaigner, "welcomes" moves by the aviation industry to improve the fuel efficiency of its planes. But says there are more pressing concerns to attend to first.
"Even if every plane leaving the UK was able to run on 20 percent biofuels from tomorrow, any carbon savings would be wiped out in less than ten years by the rapid growth in flights," he says.
"The UK Government must get to grips with this by including Britain's share of international aviation emissions in its Climate Change Bill, scrapping plans to allow airport expansion and doing more to encourage people to switch to trains for journeys within the UK and to the continent."
Virgin, unsurprisingly, doesn't believe halting growth is the answer. "We would rather see incentives for companies that are creating the technology that creates the CO2," says Charles.
"If we can fly a plane on biofuels from algae in three to six years and save 40 percent carbon emissions, that is going to deliver far more CO2 savings and more quickly than the Climate Change Bill, that is going to take years to go through Parliament."
For now, Virgin is analyzing the data from Sunday's flight with results expected in the next few weeks.
Looking ahead, Charles says biofuels could be a reality on commercial flights in three to six years. "The rate of technological change is very rapid," he says. "Two years ago it was not foreseen that you could fly a plane on biofuel. This week it happened. Within a year's time spectacular changes could happen." E-mail to a friend