In a major triumph for alternative energy researchers and enthusiasts, an experimental, solar-powered plane Thursday successfully completed a 26-hour flight powered by 12,000 solar cells and sunlight-powered lithium batteries.
The Solar Impulse, a slender, long-winged airplane, flew through the night over Switzerland, fuelled by energy it collected during the previous day. Solar Impulse reached a height of 28,000 feet and a top speed of 78 mph in what project coordinators called the longest test flight of a piloted, solar-powered aircraft.
"We don't need to prolong the flight," a project team member tweeted Thursday morning. "Everything we wanted to prove with this flight has been proven ... and more."
The solar plane project was launched at the end of 2003 under the guidance of Bertrand Piccard, the first person to complete a nonstop balloon flight around the world.
"This is a highly symbolic moment: Flying by night using solely solar power is a stunning manifestation of the potential that clean technologies offer today to reduce the dependency of our society on fossil fuels," said Piccard, in a statement.
The aircraft landed where it had taken off - in Payerne, Switzerland. Andre Borschberg, 57, a former Swiss air force fighter pilot, flew the plane.
Dan Olds, an analyst with The Gabriel Consulting Group, called the flight a "showy win" that should help organizers gather support for solar power and solar-powered vehicles, in particular.
"What it basically proved is that if you have enough solar cells, you can keep one guy in the air almost indefinitely," Olds said. "The wing area of the plane, where the solar collectors are placed, is bigger than almost every commercial airliner. So it gathered enough energy during the day to both keep the plane aloft and to store up enough juice to keep it flying during the night. It's an interesting and showy demonstration of what solar power can do, but solar planes aren't coming our way anytime soon, if ever."
However, while we may not be flying to our next vacation or business trip on a solar-powered commercial jet in the near future, Olds said airplanes could get an energy boost from solar power.
"Down the road, we will probably see all sorts of vehicles get a boost from solar cells on their exteriors," he added. "But there are quite a few hurdles in the way. The first is the cost/benefit analysis. Are the cells efficient enough to actually pay off? And there are also durability considerations. Are they reliable enough, do they need special cleaning or servicing?"
Solar cells have been powering some novel projects. NASA's robotic rovers, which have been working on the surface of Mars, have been powered only by solar power. Astronauts and robots have worked hand in hand to install a massive solar array on the backbone of the International Space Station to power the orbiter.