The end is finally in sight for the Solar Impulse 2. After a grueling series of flights that have spanned more than a year, the solar-powered aircraft is almost home. In the wee hours of the morning of July 24, the Solar Impulse 2 departed from Cairo, and is slated to reach its place of origin, Abu Dhabi, in the next two to three days. While this isn’t necessarily the most exciting leg of the journey in terms of geography or difficulty, it’s the last one — for now.

The incredible 16-month trek has proven that completely clean energy can indeed be used to power aircraft, even for the most ambitious trips. Swiss aviators Andre Borschberg and Bertrand Piccard have alternated being in the cockpit of the solar-powered plane for all of its journeys, and as Piccard told Reuters, “The round the world flight ends in Abu Dhabi, but not the project.”

And the project is an impressive one, to be sure. The four engines of the Solar Impulse 2 use no fuel whatsoever, instead relying upon the 17,000 solar cells in the wings and associated batteries to provide the necessary energy. The plane, made of carbon fiber, has a wingspan longer than that of a Boeing 747, but weighs just about the equivalent of a family car. Capable of reaching altitudes of up to 8,500 meters (28,000 feet), the solar-powered plane cruises at around 34-62 mph. Sure, it’s not the fastest way to get around the world, but it’s (almost) gotten the job done.

“The project is a big promotion of clean technologies around the world and the legacy of Solar Impulse is the created international community,” Piccard said.