A solar-powered plane, known as the Solar Impulse, is cable of flying both day and night without fuel, courtesy of 12,000 photovotaic cells and batteries. The plane, “born in Switzerland”, is set to commence a cross-country journey from San Francisco to New York on May 1, following a test flight in the Bay area on Friday. It is scheduled to make a number of stops along the way, flying some 20 to 26 hours each leg.

In the face of long standing concerns about global pollution from jet aircraft, Solar Impulse is a positive step, but still a ways from being a practical one given the size of the one seat aircraft and a top speed that is only about 40 mph.

But its still pretty cool. The major goal of the project is for a round-the-world flight, now scheduled for 2015. Here’s a look at an earlier 2010 test flight of Solar Impulse, back when its goal for a global flight was still scheduled for 2012…