A solar energy plane made the world's first international flight powered by the sun on Friday to show the potential for pollution-free air travel.

The Solar Impulse took off from an airfield at Payerne in western Switzerland on Friday morning and landed at Brussels airport after a 13-hour flight.

"The objective is to demonstrate what we can do with existing technology in terms of renewable energy and energy savings," project co-founder and pilot Andre Borschberg told Reuters by telephone during the flight.

Borschberg believes such solar-harnessing technology can be used to power cars and homes. "It is symbolic to be able to go from one place to another using solar energy," he said.

The Solar Impulse project began in 2003 with a 10-year budget of 90 million euros ($128 million) and has involved engineers from Swiss lift maker Schindler and research aid from Belgian chemicals group Solvay.

The plane, which requires 12,000 solar cells, embarked on its first flight in April 2010 and completed a 26-hour flight, a record flying time for a solar powered aircraft, three months later. With an average flying speed of 70 km/h (44 mph), Solar Impulse is not an immediate threat to commercial jets, which can easily cruise at more than 10 times the speed. A flight from Geneva from Brussels can take little more than an hour.

Project leaders acknowledged it had been a major challenge to fit a slow-flying plane into the commercial air traffic system. Friday's flight was Solar Impulse's fifth. Previous flights did not leave Switzerland. A larger prototype is scheduled to fly around the world in 2013.