The sun is an incredible source of clean, free energy. The only drawback  is that when there's no sun, there's no power.

That didn't stop the Solar Impulse, a 40-horsepower zero-emissions aircraft from embarking yesterday on its first 24-hour trip. Such an endeavor wasn't without serious risk and required split-second decision making from the pilot.

Thankfully, the overnight experiment was a huge success!  "The deal is done, we’ve won, we’ve won!" blogged an exuberant Lucas Chambers, member of the Solar Impulse staff when the plane touched down. Using lithium batteries that store a charge from the 11,000-plus solar cells on the craft, the plane was able to complete it's flight without the sun.