US aircraft giant Boeing claimed Thursday a world first in putting into the air a plane powered by a hydrogen-cell battery, a breakthrough that could herald a greener future for the industry.
"For the first time in the history of aviation, Boeing has flown a manned airplane that was powered by a hydrogen battery," Boeing chief technology officer John Tracy said.
The development was "a historical technological success for Boeing (and) ... full of promises for a greener future," Tracy told a news conference at the firm's research centre in the central Spanish town of Ocana.
At the same time, the company said that although hydrogen fuel cells could be used to power small planes it did not believe they could become the primary power source for large passenger aircraft.
The test plane was a small, white prop-driven aircraft capable of carrying two people.
It flew at a speed of 100 kilometres (62 miles) an hour for about 20 minutes at an altitude of some 1,000 metres (3,300 feet) using only the hydrogen battery for power and with just the pilot on board.
It has a wing span of 16.3 metres (51 feet) and is 6.5 metres long, and weighs approximately 800 kilograms (1,760 pounds). The plane was flown over the airport at Ocana.
Hydrogen power uses "fuel cells" that tap the energy produced from the chemical transformation of hydrogen and oxygen into water.
It holds the promise of a cleaner and renewable energy resource as it produces only harmless water vapor as waste.
In the Boeing test plane, the battery was kept in the passenger seat while the pilot had an oxygen tank similar to the ones used by divers on his back. Boeing said the plane had a flying time of 45 minutes.
During takeoff, the airplane's batteries were used to provide an additional boost but while it was in the air, it relied only on the hydrogen cell.
The director of Boeing's research centre at Ocana, Francisco Escarti, said it "could be the main source of energy for a small plane" but would likely not become the "primary source of energy for big passenger planes.
"The company will continue to explore their potential as well as that of all durable sources of energy that boost environmental performance," he said, adding the test plane had the advantage of "not making any noise."
Engineer Nieves Lapena, who was responsible for the test flight, said the technology could be sued as a secundary source of energy for large planes but this would still take some time.
"In my opinion, we are talking about a delay of about twenty years," she said.
Demand for cleaner, safer and more fuel-efficient vehicles and airplanes is growing amid rising costs and concerns over pollution and climate change.
Several auto makers, including General Motors, Nissan and BMW, are working on the development of hydrogen-powered cars.
"Boeing recognizes that pollution represents a serious environmental challenge," Tracy said.
Boeing's first new model in over a decade, the Dreamliner, uses high-tech composites which reduce weight, allowing it to consume 20 percent less fuel then similar-sized planes already on the market.
The International Energy Agency has said that hydrogen and hydrogen fuel cells could play a key role in weaning energy users away from oil, gas and coal which have been blamed for climate change.