UK fuel cell specialist Intelligent Energy and aviation giant Boeing have today announced that they have successfully undertaken the first-ever manned flights of a hydrogen fuel cell powered light aircraft, but immediately downplayed expectations that we could one day undertake flights in fuel cell powered airliners.

The three test flights were carried out in Spain earlier this year and saw the two-seat light aircraft climb to an altitude of 1,000m using a combination of battery and fuel cell power before cruising at a speed of 100km per hour using power solely generated by Intelligent Energy's Proton Exchange Membrane fuel cell system.

Speaking to BusinessGreen.com, Jon Moore of Intelligent Energy said the flights represented an important aviation first and proved that manned and unmanned light aircraft could be powered by fuel cells that emit nothing but water vapour.

Boeing said that it did not envisage fuel cells ever being used to power larger commercial aircraft, but insisted the technology could still have an important role to play in making aviation cleaner.

"At the moment the onboard power systems are either parasitic to the jet engines or are charged up using internal combustion engines on the ground," explained Moore. "What this flight proves is that fuel cells can be used successfully in an aviation context and could provide a much cleaner alternative to existing auxiliary power systems."

The flights represent another significant breakthrough in the aviation industry's attempts to develop zero carbon technologies. The International Air Transport Association has set itself the target of undertaking a large-scale zero carbon flight by 2050, while earlier this year the Solar Impulse project unveiled plans to undertake a solar powered round-the-world flight by 2011.

However, while insisting that research to increase the power output from fuel cells will continue, Moore expressed scepticism that fuel cells could ever replace jet engines.

"The problem is nothing can mirror the power to weight ratio of jet engines, " he said. "When everything else has changed and we're all driving round in electric cars, jet engines are likely to be the only [carbon emitting technology] that will remain."