In utopian visions of the future, we won't have to burn anything to get anywhere. No fossil fuels, no coal, no burning of any sort.
For some, that future is already here--plenty of electric car owners run their cars using solar electricity generated from panels at their home or place of work.
It's a little trickier for aircraft though, which are more energy-intensive and have fairly significant risks should your battery run out at an inopportune moment.
However, the concept of a manned electric aircraft is certainly being investigated, and a new report from research group ASD investigates the near and further futures of electric air transport.
We're not able to bring you full details from the report--unless someone out there is willing to lend us the $3,995 it costs to download--but it looks into how electric aircraft will be powered in the future--for leisure aircraft, large solar cells on the roof of the hangar--and just what might be possible from electric aviation.
It also details how engineering is working from both the bottom up and the top down.
Hang gliders and sailplanes, which need very little motive power, are adopting electric propulsion, while some large helicopters are becoming hybrids, and airliners are using electric-powered nosewheels for movement on the ground.
As with electric road vehicles then, adoption of the technology will be gradual and varied--and the first mass production hybrid and electric light aircraft may not be far away.
Similarly to cars, several technologies will be tried in the pursuit of a truly usable option--supercapacitors, fuel cells, batteries and energy harvesting are all avenues being explored.
The technology may be further on than you'd expect, too. Beyond Aviation experimented a few years back with an electric Cessna 172:
Other companies, like Slovenia-based Solar Flight, have experimented with light solar gliders, like the main image on this page. Difficulties include making the solar panels smooth enough to be used on the aircraft's wings, and ensuring the heat of the panels doesn't damage the composite body--but it's a step closer.
Ground-based solar would eliminate these issues, but has its own problems--once you're up in the air, the power you have is all you've got.
It will be a long time until we see electric airliners, but just as with electric road vehicles: the technology is coming.