Overheated lithium batteries for the solar-powered Solar Impulse 2 this summer forced the single-seat experimental plane to sit out the winter in a hangar in Hawaii, part-way through its historic round-the-world flight. But dreams of solar-powered flight are taking off despite this grounding.
An unlikely, but well-heeled trio of corporate giants has an interest in Swiss-based Solar Impulse's progress. Google, Facebook and Airbus Group each are working on their own solar-powered, unmanned aerial vehicles, better known as drones. Several other smaller firms worldwide also are involved in solar-powered drones.
The solar-powered Solar Impulse 2, piloted by Andre Borschberg, approaches Kalaeloa Airport in Hawaii. Google and Facebook say they want to loft autonomous aircraft, with wingspans rivaling those of Boeing 767 jets, miles in the air. Their main goal is for the aircraft to perform the same relay functions as cell towers over areas around the globe that have yet to connect online.
Airbus sees a future for its Zephyr aircraft in communications, weather, surveillance and other areas.
The goal is to keep these planes continuously in the air for months or years. "It's definitely a niche area," said Mike Blades, an analyst with Frost & Sullivan. "But eventually, anything you can do with communication satellites, you will be able to do (with solar drones)."
Airbus calls its vehicles high-altitude pseudo-satellites, or HAPS, which describes most solar drone projects. Small drones, including those that Amazon.com says it will use to deliver goods, can't reliably run on solar power because they are often below sun-shielding clouds. Replacing satellites is an attractive opportunity. Satellites are expensive to develop and launch, and it is getting more difficult to find open orbits among all the other craft, Blades says. He estimates that, for the foreseeable future, it would cost 10 times as much for satellite development and placement as it would to develop a drone and get it properly positioned and operating.
Cost comparisons are difficult, though, because no company has had a drone up for longer than a couple weeks. The technology for Google, Facebook and Airbus is largely the same. All top surfaces of an ultra-light and spindly aircraft are covered in dark sheets of hair-thin solar cells that charge a heavy load of batteries. The engines and instruments feed off the batteries. Airbus would get a direct return on its investment through aircraft sales. Google's and Facebook's gains would come primarily from bringing more people online, people who presumably would use their services and click their ads.