Sustainable Energy

'The definition of adventure': Solar Impulse 2 completes round-the-world flight

Solar Impulse completes world tour

The pilots of the Solar Impulse 2 have described their year-long attempt to fly around the world powered solely by the sun as the "definition of adventure."

Speaking to CNBC shortly after landing in Abu Dhabi Tuesday, pilot and chairman Bertrand Piccard said the round-the-world trip had "some elating moments but also difficult moments, setbacks even, and this is the definition of adventure."

Solar Impulse 2 landed in Abu Dhabi more than a year after its initial take off, marking the end of an epic 25,000-mile (40,000-kilometer) journey. The plane made 16 stops, including in India, China, the U.S., Italy, Egypt and the United Arab Emirates -- where it first took off.

The Swiss-engineered single-seater aircraft is powered by 17,248 solar cells and runs on battery power at night. Its average airspeed was 46 mph, though that increased during the day when the sun's rays were strongest.

It took 70 hours for the plane to cross the Atlantic and 118 hours across the Pacific.

On Sunday, Piccard took off from Cairo in Egypt to complete the last leg of the journey, landing 48 hours and 37 minutes later in Abu Dhabi at 2:05 a.m. CEST on Tuesday.

"It really shows that you can do incredible things with clean technologies, renewable energies, like flying day and night on solar power with an airplane (with) unlimited endurance because you don't need to refuel," Piccard told CNBC.

The trip has not been without its hiccups. Last year, the plane suffered "irreversible damage to overheated batteries" after a record breaking flight between Nagoya and Hawaii that lasted more than four days. It had to be grounded for several months while repairs took place.

Efficiency and endurance

What’s next for Solar Impulse?

"We arrived… thanks to two things: first, that the airplane is using solar energy as the only source of energy and second, that this airplane is extremely energy efficient," André Borschberg, chief executive and pilot of Solar Impulse, told CNBC.

"Thanks to this efficiency… (we can) fly through the night with an airplane powered by the sun only," he added before going on to explain that Solar Impulse 2 was the first airplane ever developed with "unlimited endurance."

The world first trip has drawn praise from around the world.

In a live streamed chat with Piccard during the last hours of the flight, United Nations secretary general Ban Ki-moon expressed his "deepest admiration and respect" for the pilot's courage. "This is a very historic day, not only for you (but) for humanity," Ki-moon added.

While the journey is an undoubted feat of human endurance, for Piccard the message is bigger.

This plane just ended its round-the-world trip—without fuel

"Very often when you speak about the protection of the environment it's boring and expensive and we wanted to demonstrate that it's exactly the opposite, that you have now clean technologies that are profitable, they create jobs, they make profit, they sustain growth and at the same time if they were implemented everywhere they would divide by two the CO2 emissions of our world and save natural resources and decrease pollution," he said.

Piccard added that best way to demonstrate this was to embark on a "spectacular" project like Solar Impulse that would attract the attention of people and offer solutions. "This is one of the solutions… not only for aviation, but for energy in general to be more efficient with natural resources of our planet and show that there are other ways of thinking and other ways of doing."

The Associated Press contributed to this report.

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