Solar Impulse 2, which would be the first plane to travel around the world powered only by solar energy, began its journey to Hawaii from Nanjing, China, on Saturday.

Solar Impulse CEO Andre Borschberg, who is piloting the plane, was planning a landing in Nagoya, Japan, early Monday to wait out a weather front before continuing to Hawaii.

Solar Impulse 2 co-founder Bertrand Piccard said he hopes the plane’s journey will showcase the power of clean technology. "Allowing an airplane to fly day and night with no fuel … We see that nothing is impossible," Piccard said. "Our goal is to raise millions and millions of voices of people who say, ‘Yes, we would like clean technologies for the future.’"

The journey across the Pacific will be the longest leg of the 25,000-mile trip around the world. Piccard said the pilots prepared to operate the plane nonstop for 120 hours with self-hypnosis and meditation.

Solar Impulse 2 pilots hope to become the first to fly a solar-powered plane around the world, and the key to their success is the flight from Nanjing, China, to Oahu.

The Solar Impulse 2 took flight for the 5,000-mile journey Saturday. The trip across the Pacific to Kalaeloa Airport will be the longest leg of the trip as Solar Impulse 2 CEO Andre Borschberg flies the plane alone, packed in the tiny cockpit.

"Hawaii — we’re coming," said Solar Impulse 2 pilot and co-founder Bertrand Piccard in a telephone interview from China. "We look forward to being in Hawaii."

The overall reason for the flight is to spread awareness about the capability of renewable energy, Piccard said.

"Our goal is to make a revolution in the mindset of the people when they think about clean technologies," he said.

Weather has proved to be a challenge for the Solar Impulse 2 crew as the team delayed the plane’s Hawaii trip multiple times before the takeoff Saturday. Early Monday the plane was to stop in Nagoya to wait out a weather front, prolonging what the team had hoped would be nonstop five-day leg.

Unsafe wind speeds pushed back the departure date from Chongqing to Nanjing, China, several times until Piccard took flight April 20 to the plane’s last destination before flying to Hawaii.Choosing the right window to fly was crucial because the plane — with the wingspan of a commercial airliner and the weight of a car — is sensitive to turbulence, Solar Impulse said.

More than 17,000 solar cells cover the plane’s 72-meter wingspan. The solar cells combined with the four electric motors and lithium batteries replace the need for fossil fuel.

Through the round-the-world journey of Solar Impulse 2, the team wants to show the power of renewable technology, Piccard said.

"Allowing an airplane to fly day and night with no fuel … We see that nothing is impossible," Piccard said. "Our goal is to raise millions and millions of voices of people who say, ‘Yes, we would like clean technologies for the future.’"

Completing the most challenging leg from China to Hawaii marks the seventh stop for Solar Impulse 2 as the plane travels across the globe.

After Hawaii, Solar Impulse 2 will fly to Phoenix, on to a yet-to-be announced Midwest city, then to New York.

Borschberg, 62, graduated from the Massachusetts Institute of Technology and trained as a pilot in the Swiss air force, flying for 20 years. He is also an entrepreneur who started Innovative Silicon, a microprocessor company.

The Solar Impulse 2 flight is not the first world trip for Piccard, 57. The founder and chairman of Solar Impulse completed a nonstop, round-the-world balloon flight in 1999. Piccard said his experience has helped him prepare for the Solar Impulse 2 journey.

"In the balloon I spent five days, another nine days and another time 20 days when I flew … around the world. But the balloon, if you do nothing, the balloon stays in the air," Piccard said. "It was much longer but also easier. Solar Impulse (has) only one pilot to fly the plane. You have the autopilot, but if the autopilot fails you have to fly the plane yourself. You need to be always in control … This makes it very demanding."

Piccard has been preparing for the round-the-world journey all of his life, he said. "(I) trained my memory, trained my concentration, trained my skill to work for a very long time without needing to take a break, and now I use it for Solar Impulse."

Piccard said he is confident in his abilities, especially after the 72-hour flight simulator tests that he and Borschberg completed.

"It is interesting to see that over the three days and three nights (there was) absolutely no deterioration of the concentration skills. We are well-trained, and this will be a big help for the flights of several days and several nights," Piccard said.

To maintain concentration while sitting in a cockpit 4 feet wide by 61⁄2 feet long, the pilot will practice yoga, meditation and self-hypnosis.

"You must remain calm," Piccard said, noting he prefers self-hypnosis while Borschberg uses different breathing techniques.

Piccard said the self-hypnosis helps him push through anxiety and fatigue while allowing him to be mindful of the task at hand.

"You do something that lasts for very long; don’t count the hours," Piccard said. "If you do that, you are in trouble. You have to live in the present moment and you have to carry your present moment awareness of yourself, with yourself. Then the flight … is not a problem anymore."

Accommodating sleep requirements will be most important as the pilots navigate the plane across the long distances, Piccard said.

"The most crucial thing we will have to manage is the naps of 20 minutes," he said. "If we do these naps of 20 minutes, we’ll be fine. If we cannot do that for a reason or another, technical or stress or human sickness … it will be a big problem and it will be very difficult."

During the day when the solar panels are generating power, the plane will climb to over 27,000 feet. At night it will run on battery power and gradually drop to below 5,000 feet.

If the equipment were to malfunction, the plane is designed to glide, Piccard said.

"From 9,000 meters to the ground it would take four hours to glide. (We) wanted to use very little energy to stay airborne," said Piccard in an in-flight press conference from Chongqing to Nanjing.

The project is estimated to cost $100 million. Sponsors include Omega SA, Google Inc., the Schindler Group, Solvay SA and ABB Ltd.