CHANTILLY, Virginia (AP) — The plane parked outside the airport looks more like a giant exotic insect or maybe an outsized toy.
When it's in flight, there's no roar of engines. It's strangely quiet. And as it crisscrosses the U.S., the spindly plane doesn't use a drop of fuel. Day, and even night, it flies on the power of the sun.
It's that fact that has the U.S. energy secretary, and the plane's two pilots and fans around the world, so excited.
The one-man craft called Solar Impulse  has been flying cross-country in short hops as part of a 13-year, privately funded European project that is expected to cost $150 million.
Ernest Moniz, who heads the U.S. Department of Energy, praised the effort at a news conference Monday in Washington, where the plane landed early Sunday morning. Moniz said it highlighted a cleaner energy future for the nation.
"It's also a poetic project," said Bertrand Piccard, one of the pilots. "It's about flying with the sun. It's about flying with no fuel."
It's not that the experimental plane is going to change the way the rest of us fly, Moniz said. But it may change the way we drive and the buildings we live in sooner than we think.
The lightweight technology will pay off on the ground far more readily than in the air. This project should lead to cleaner appliances, greener cars and more energy-efficient building, said Solar Impulse CEO Andre Borschberg, who also is one of the pilots.
In an in-flight interview Friday, Borschberg said this experiment isn't about aviation being cleaner. Airplanes only produce 3 percent of the world's heat-trapping gases, he said.
"The potential is on the ground, the potential is not in aviation," he said. "On the ground, the potential is huge and is readily available."
Perhaps as early as 2015, an updated version of this solar plane will be flown around the world. Last year, the same plane flew from Switzerland to Morocco.
When he first came up with the idea a decade ago, Borschberg said he was told by experts: "Your project is impossible."
Now instead, Moniz said, Solar Impulse is highlighting four high-tech green energy fields that his office is trying to promote: solar power, better batteries that allowed Solar Impulse to fly at night, lightweight materials and integrating everything.
They'll pay off on the ground quickly, Moniz said. Take the lightweight carbon fiber and lighter solar cells. Once applied to rooftop solar panels, that will bring down costs for houses because much of the problem currently is the size and weight of the panels, he said.
Solar Impulse carries more than 11,000 solar cells — 10,746 of them on the long wing that stretches 208 feet. Although it has the wingspan of a jumbo jet, the entire plane weighs just 3,500 pounds (1,580 kilograms), the size of a small car.
The plane parked outside the airport looks more like a giant exotic insect or maybe an outsized toy. When it's in flight, there's no roar of engines. It's strangely quiet. And as it crisscrosses the U.S., the spindly plane doesn't use a drop of fuel. Day, and even night, it flies on the power of the sun.