Abu Dhabi –  is no conventional environmental activist. He hopes to raise awareness about the potential of renewable energy by flying a solar-powered aircraft around the world.

"What we want to do is to fly day and night to show that, with renewable energies, you can have unlimited duration of flight, no restriction," Piccard told AFP at the World Future Energy Summit in Abu Dhabi, where he had a booth to promote his venture.

The 51-year-old Swiss psychiatrist plans to fly his one-of-a-kind ‘Solar Impulse’ around the world over 20 to 25 days, traveling at an average of 70 kilometres (43 miles) an hour.

He will split the flying time with Andre Borschberg, a former Swiss fighter pilot.

"We believe that if an airplane can fly around the world with no fuel, nobody can say after that it's impossible to do it for cars, for heating systems, for air-conditioning, for computers and so on," he said.

The prototype of Solar Impulse made its first test flight near Zurich in December. The plane is made of carbon fibre, with solar panels along the top of its roughly 64-metre (209-foot) wingspan.

The aim is for the solar panels to absorb energy to power the aircraft during the day, and at the same time store energy in lithium polymer batteries to run the engines at night.

Piccard presents his "impossible" solar plane

Building the impossible
After aircraft manufacturers said Piccard's specifications would be impossible to meet, he turned to a racing yacht manufacturer to build the airframe.

"They did not know it's impossible, so they did it," he said.

The plane is powered by four electric engines, each making a maximum of 10 horsepower. Piccard said that, despite having a wingspan close to that of an Airbus A340, Solar Impulse weighs only 1,600 kilogrammes (3,500 pounds).