Long-distance flights with zero emissions are entirely possible...as long as you don't rush. Solar Airship 1 will take 20 days to fly around the equator, a total distance of about 40,000 kilometers (about 25,000 miles). The 151-meter (495-foot) airship will be covered with solar film on its entire upper surface, covering an area of about 4,800 square meters, or about 90 percent of an NFL stadium.
During the day, the solar panels will power the airship's electric propulsion system, while storing additional electricity for nighttime flights by electrolyzing water into hydrogen. At night, the hydrogen will power the spacecraft via fuel cells.
The spacecraft will be piloted by a team of three: former French astronaut and air force pilot Michel Tognini, paraplegic plane crash survivor and stunt pilot Dorine Bourneton, and serial adventurer and "inspiration" Bertrand Piccard, who successfully completed the first non-stop balloon voyage around the world in 1999, and in 2015-16 drove "Solar Impulse 2" (Solar Impulse 2) for the first 16-and-a-half-month solar flight around the world.
The European airship team expects to reach an average speed of just over 83 km/h (52 mph), which is less than one-tenth the speed of an average fossil-fuel airliner. But airships do have some key advantages -- for example, you can dock and launch anywhere you like, without the need for a runway.
In fact, projects such as AirYacht and bootylicious Airlander aim to resurrect airships as a luxury mode of passenger transport, while others believe that hydrogen-filled airships are the future of zero-emission cargo transport, capable of carrying 8-10 times the capacity of cargo planes, costing only a quarter of the price of cargo planes, and being 10 times faster than freighters.
Solar Airship One is powered by renewable energy, but one of its key components is not. Its rigid structure contains 15 separate envelopes containing a total of 50,000 cubic meters (1.77 million cubic feet) of helium. Fun fact: Helium is the only element on Earth that is completely non-renewable, because when it escapes into the air, it rises directly out of the atmosphere and into space.
The European airship team is preparing for a zero-carbon circumnavigation in 2026, staying near the equator at an altitude of about 6,000 meters (19,700 feet).