It looks like a fragile matchstick model glued together in somebody's basement, except that it is large enough to fill an airline hangar. And it flies. Barely.
On its first test flight here last month, the Solar Impulse HB-SIA rose less than a metre off the ground and travelled just over the length of three football fields. Scoff if you must, but that "flea-hop," as its designers call it, might represent the launch of a whole new world of aviation: the truly eco-friendly airplane.
"I don't foresee a solar-powered A380 or 787 flying any time soon," says Paul Steele, director of aviation environment with the International Air Transport Association, whose members include the world's major airlines. But Steele points to similarities with the Wright brothers' flight in 1903, which lasted only 12 seconds. "After that hop in Kitty Hawk, would anyone have thought that 40 years later they would be flying jets across the Atlantic with 100-plus people on board?" he asks.
The IATA has signed on as a sponsor of the Solar Impulse project as part of its commitment to cut carbon emissions by 50 per cent from 2005 to 2050, and hired Steele, a former chief operating officer of the World Wildlife Fund, to help lead the way.
To cut greenhouse-gas outputs, airlines are looking in the short term to new fuel-efficient planes, improved air-traffic-control measures and the gradual introduction of biofuels. But visionaries are already proposing radical changes to aviation that will not only protect the environment but also change the entire experience of flying. Just don't expect the science-fiction scenarios to kick in too soon.
"Remember that big technology improvements happen within a generation shift of aircraft," Steele says. Only after 2020 will aircraft makers incorporate outside-the-box ideas into future designs.
Here's a look at some of the environment-friendly proposals being adopted or studied by the world's airlines:
Solar power In 2012 or 2013, Solar Impulse founders Bernard Piccard and André Borschberg hope to fly a newer model solar-powered aircraft around the world. They will take four-day turns in the tiny cockpit, using vibrating vests to stay awake. Weight limitations mean there will be no room for passengers, a second pilot or a proper toilet.
Piccard came up with the idea for a solar-powered aircraft after he and Brian Jones made the first non-stop around-the-world balloon flight in 1999. "We almost failed because of a dependency on fuel," he says. "I made a vow that next time I flew around the world it would be with no fuel."
So he found funding, brought in Borschberg, an engineer and pilot who shared his vision, and started designing a craft that could fly at night using the sun's energy stored in batteries.
Using lightweight materials, the Solar Impulse designers built a plane with the wingspan of an A340 and weight of a single automobile.
With the enthusiasm of an after-dinner inspirational speaker, Piccard explains that even if his project never has commercial applications, it will focus attention on using new technologies to save the environment.
"This plane is not there to make a revolution in aviation," he says. "It's there to make a revolution in thinking." The IATA's Steele says there will be a role for solar energy in commercial flying, even if it never becomes a direct replacement for fuel. "Could we put solar panels on the wing surfaces, could we put them on the top of the fuselage, and use those solar panels to provide the power for in-flight systems to reduce the need for fuel burn?"
After 2050 The mid-21st century will see the introduction of a liquid-hydrogen-powered airplane carrying more than 1,000 passengers, IATA's Steele predicted in Departure 2093 - Five Visions of Future Flying , a book published last year by Finnair.
Using a blended-wing design for streamlined flying, the plane will have a futuristic look. To make it work, passengers will be spread out along the axis of the wings, instead of in rows in the fuselage.
In Departure 2093, as he pretended to look back at the first hydrogen plane from the distant future, Steele wrote that passengers felt claustrophobic because there was no access to windows. "However, the modified version, incorporating advanced lighting and screen technology for the interior, satisfied customer expectations," he wrote. "The screens provided a view outside the plane, and the experience was like floating over the clouds."
Hydrogen did not factor into his predictions for the near future. In an interview, Steele said that hydrogen, unlike biofuels, can't be mixed with traditional fuel in existing aircraft, and that its use would require a whole new pipeline system at the world's airports.
In the book, Steele did predict the introduction of a new breed of short takeoff and landing planes for regional routes that would use electric power elements, have significantly reduced noise and use runways as short as 500 metres.
But some predictions are less rosy. Atte Korhola, a professor of environmental change at the University of Helsinki, mused that the end of this century might see the return of airships that would use air streams and winds in the upper atmosphere.
"The future of aviation," he wrote, "may mean the abandonment of the Western concept of time: Perhaps we will no longer fly according to the clock and timetables, but when it is favourable, inexpensive and sensible to do so."
The near future Three new long-distance airplanes will drastically cut fuel use and therefore emissions through the use of lightweight components and streamlined design.
The Airbus A380, introduced in 2007, is "probably the most fuel-efficient plane in the sky," IATA's Steele says. Carrying 555 passengers, it consumes less than three litres of fuel per 100 kilometres per passenger, according to Airbus. Meanwhile, Boeing's Dreamliner, which made its first flight in December after a two-year delay, promises fuel use 20 per cent lower than similarly sized airplanes. As for smaller aircraft, less fuel burn and lower emissions are being promised by Bombardier for its CSeries and by Embraer for its E-Jets.
The gradual introduction of biofuels will also cut emissions. Over the past two years, five carriers - Virgin Atlantic, Air New Zealand, Continental Airlines, Japan Airlines and KLM - have made successful test flights blending biofuel with their regular fuel.
Biofuels made from corn and soy have been criticized for competing with food production. But these can't be used in the air because they freeze at high altitudes, Steele says. Instead, airlines are looking at fuel made from jatropha (an oily seed), camelina (a member of the mustard family) and algae that can be grown in deserts, salt water and waste water.
Airlines will increasingly mix biofuels with their jet fuel when the price comes down. "Because there is such a small quantity of these things being produced, the cost is quite high," Steele says. But as investments in new crops lead to greater availability, he adds, the price will drop over the next three to five years.
New air-control systems in Canada, the U.S. and Europe will also play their part in fighting climate change. As satellite tracking replaces ground radar stations, planes will be able to fly more direct routes. That will mean lower fuel use for the airlines, and shorter flight times for passengers. Nav Canada alone estimates its new technologies and procedures will save 8.4 million tonnes of aviation-related greenhouse- gas emissions from 2009 to 2016.
Steele says the aviation industry is committed to environmental change. "We have to take action."
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