A solar powered airplane just flew from Hawaii to California, in the process taking us one step closer to the future, where clean, abundant, free solar power increasingly replaces dirty and dangerous fossil fuels.
Solar Impulse 2, which seats one person and has wings longer than those of a Boeing 747, originally took off from Abu Dhabi, the capital of the United Arab Emirates, in March 2015. Since then, piloted alternately by Bertrand Picard and André Borschberg, the plane has stopped in Muscat, Oman; Ahmadabad, India; Varanasi, India; Mandalay, Myanmar (Burma); Chongqing, China; Nanking, China; Nagoya, Japan and now Mountain View, California.
The leg from Japan to Hawaii took five days and nights (117 hours), while the leg from Hawaii to California took three days and two nights (62 hours) — which included a couple of hours flying above the Golden Gate bridge creating photo opportunities while waiting for night to fall.
It’s a slow way to fly certainly; the plane’s maximum speed is just 87 miles per hour, and it’s usually flown even slower to conserve energy. Plus, conditions need to be near perfect for takeoff and landing, with very little wind—which often means taking off at dawn and landing at night.
Still, the plane, which is powered by 17,000 solar cells that feed four 41 kWh lithium polymer batteries that each power one propeller, is breaking records. And its human pilots (Borschberg flew the Japan to Hawaii route, while Picard flew the Hawaii to California route) are doing the same. While most people complain about being stuck in a plane seat for longer than a few hours, these men do it for days at a time — and they don’t watch any movies!
To me, one of the most interesting aspects of the plane’s long-distance flights is the way it needs to climb to high altitude (roughly 30,000 feet) while the sun is out, so that it can drift slowly downward overnight, and then use battery power to maintain altitude while waiting for the power of the sun’s rays to power another climb to altitude. The following graph, which depicts both the altitude and the battery power stored during the California leg, shows that cycle.
The plane is scheduled to make three more stops in U.S. before crossing the Atlantic, and if you get a chance, I urge you to see it. The future is bright!