The solar-powered airplane Solar Impulse 2 (Si2) completed its historic round-the-world flight today, landing safely in Abu Dhabi after a record-breaking emission-free journey around the world without using a single drop of fuel.

By Erik Kirschbaum

In an epic demonstration of the potential of clean technologies, Swiss adventurer Bertrand Piccard landed the 5,500-pound sun-powered Solar Impulse 2 airplane in Abu Dhabi on Friday to complete the first circumnavigation of the globe with an aircraft that did not use any fuel.

Finishing the 17th leg of the history-making journey from Cairo at the same airport here where the airplane first took off on its mission on March 9, 2015, Piccard and his compatriot Andre Borschberg had alternated solo flights at the controls of the single-seat airplane that derives its power from 17,000 solar cells embedded in the wings — which are as large as a Boeing 747.

Piccard and Borschberg had been working on the project for 12 years and were supported by a crew of engineers, meteorologists and other specialists as mission control in Monaco.

The Solar Impulse 2, which is made out of carbon fiber and weighs about the same as a small truck, drew enthusiastic crowds of thousands of spectators at each of the stops, eager to learn more about the potential of clean technologies.

Aside from flying nonstop over the planet’s largest two oceans, the Pacific and Atlantic, and past some of the world’s most iconic landmarks such as the Himalaya, San Francisco’s Golden Gate Bridge, the Statute of Liberty in New York and the pyramids in Egypt, the pilots also set a number of aviation records. Borschberg shattered the record for endurance by flying solo for 117 hours and 52 minutes, or five days and five nights, non-stop across the Pacific Ocean from Nagoya, Japan to Hawa ii – a distance of 8,924 kilometers/ 7,272 miles.

Excess energy collected during daylight hours was stored in the airplane’s four batteries and used to keep the plane flying overnight. It was able fly as high as 28,000 feet (8,500 meters) but usually flew at lower altitudes at night to conserve energy. The pilots trained at staying alert for long stretches of time by practicing meditation and hypnosis that allows them to stay awake for multiple days interrupted only by several short naps each 24-hour cycle.

“Everywhere we went the reception we got was emotional and deep,” said Borschberg, who flew the penultimate leg to Cairo from Seville, Spain and said he was thrilled to prove that a solar-powered airplane could in theory “fly almost forever” because it does not need any fossil fuels to stay aloft. “It was great to show so many people why we’re doing this project, to show them the possibilities of clean technologies, conserving energy and en ergy efficiency.”

Starting in Abu Dhabi, the plane flew to Muscat, Oman, then across the Arabian Sea to Ahmedabad, India, before heading to Varanasi, India and then to Mandalay, Myanmar. From there it was to China for stops in Chongqing and Nanjing. Borschberg had planned to fly directly to Hawaii but was forced to re-route to Nagoya, Japan due to weather. The longest flight then followed to Kalaeloa, Hawaii, the first of seven stops in the United States: Mountain View, California; Phoenix, Arizona; Tulsa, Oklahoma; Dayton, Ohio, Lehigh Valley, Pennsylvania and then New York. From there, Piccard flew across the Atlantic to Seville, Spain for the second longest flight – just over 71 hours. The penultimate stop was in Cairo.

Pictures free for editorial usage: Si2 / The Green News