RABAT  - A solar-powered plane on a record-breaking trip to showcase renewable energy attempted a flight over the Moroccan desert Thursday, even as a key summit in Rio discussed "greening" the world economy.An earlier attempt by the Swiss-made Solar Impulse to reach Ouarzazate last week was foiled by rough conditions but the giant sun-powered plane flew away from Rabat into a clear sky Thursday at dawn."The sky is magnificently beautiful and I am pretty confident of arriving at the destination," pilot Andre Borschberg told AFP. "Mother Nature seems to be more favourable than the last time." When Borschberg on June 13 made his first attempt to cross the desert on the final stage of a trip that has taken him from his native Switzerland to Spain and then to Morocco, he had to turn round because of strong winds and turbulence near the Atlas mountains.Earlier this month, fellow inventor and adventurer Bertrand Piccard - who made the first non-stop around-the-world balloon flight 13 years ago - flew Solar Impulse from Madrid to Rabat.It was the first ever flight between two continents by an aircraft that does not require a single drop of fuel."Our journey shows that there are other ways of saving energy and of saving the environment and the planet," Borschberg told AFP from the cockpit of his plane, which looks like a giant glider.About half-way into the final and toughest leg of the solar plane's trip, no incident was reported and the craft was flying over the Atlantic towards the port city of Casablanca at about 62 kilometres per hour (38.6 mph).It was expected at around 11:30 pm (2230 GMT) in Ouarzazate, where the Moroccan authorities plan to build the largest solar power station in the world."I can see far away the Moroccan coast in a superb blue... Today everything seems possible. In Ouarzazate, the weather forecast is good," Borschberg said on the phone.Speaking of his foiled bid the previous week, he said that people "should not talk of failure, but of experience. It's training, you learn a lot of things."The flight was described as the most challenging Solar Impulse has yet faced because of the arid, baking hot nature of the terrain and the proximity of the mountains, which are more than 3,000 metres (9,800 feet) high.The giant high-tech aircraft, which has the wingspan of a jumbo jet but weighs no more than a medium-sized car, is fitted with 12,000 solar cells feeding four electric motors driving propellors.Ouarzazate is 550 kilometres (340 miles) from the Moroccan capital. The flight is expected to take about 16 hours because of the slow speed of the prototype aircraft and the unpredictable climate.The flight has been jointly organised by the Swiss Solar Impulse company and the Moroccan agency for solar energy (Masen). When he reaches Ouarzazate, Borschberg will fly over the future site of the solar power complex.Masen is responsible for building a power station with an initial capacity of 160 megawatts and plans to raise this capacity to about 500 MW to 2015.Last month, the solar-powered plane made the 2,500-kilometre (1,550-mile) journey from Madrid to Rabat, its longest to date and its first between continents, after an inaugural flight to Paris and Brussels last year.The flights are intended as a rehearsal for the goal of a round-the-world trip in 2014 by an updated version of the plane.