Could one realistically power air travel with renewable energy sources?

Peanut-explosive propelled gliders?

I think what we need to consider at least as much as the source of fuels and materials is the scale we’re talking about. Probably not renewable to have everyone flying around, but maybe a few people now and then.

@incendiary_dan Dangit, I want my jetpack.

there have been several planes that have been built that are powered by burning Hydrogen and Oxygen, though not exactly renewable, all that pops out of the exhaust is really hot water vapor. They’re just expensive as hell.

i’m not sure but if anyone can Dr Nakamat can. Over 3000 inventions patented, but alas not an invention to treat his incurable megalomania.

This guy talks about human powered flight. His speech is very dull and I am very tired, so I’m not going to listen to it now, but it looks interesting.

http://www.ted.com/talks/lang/eng/paul_maccready_flies_on_solar_wings.html

Human powered plane

Solar powered plane

Those were both made in the 70’s, so I’m sure there are better ones that have been made.

I think it’s likely that we will eventually use massive train systems for efficient transport, instead of airplanes.

Biodiesel is a likely choice. It has similar specific energy density as other fuels.
Batteries and fuel cells are out for practical flights. The best batteries are about 1/80 the energy density of diesel fuel. Unless you are willing to travel very slowly, solar is out since the best sun load you can expect is about 1 kW per sq meter, and with solar cells running at 10% efficiency that means you need about 10 sq meters for 1 hp. (Rough numbers.) Sure, you can make one plane that works but it flies at a crawl and takes up as much surface area as your house.
The Laws of Physics are hard to beat.

I think a solar-powered airship would be awesome. But slow, as @worriedguy points out. I think people are too used to getting there fast: London to New York in five hours, not five days.

Renewable energy will never give us the volume and relative cheapness of air travel today. We need cheap oil for that and it is rapidly running out.

Post removed by yours truly. Postmortem: Stupid remark resulting from not reading earlier posts.

I believe hydrogen has adequate specific impulse to power a jet engine.

So, assuming that electricity can be generated entirely from renewable sources someday, then electricity can be used to manufacture hydrogen, and hydrogen can be the fuel used to power jet engines.

The Hindenberg illustrated why pure hydrogen as fuel is not so clever. Unless you have a way of creating and using it “on the fly” (pardon the pun). Perhaps by breaking down water into Hydrogen & Oxygen?

The Hindenberg used hydrogen as a lifting gas, not as fuel. Bad idea! Modern derigibles use helium, which is inert and not combustible. As a fuel, hydrogen is no more dangerous than petrol (that’s not to say that it isn’t dangerous, for it is, as is petrol). It just has to be contained differently because it’s a gas a room temperatrure, rather than a liquid.

@HungryGuy H2 does have the potential except the tanks required to store the required quantity of fuel (at 5000 psi) are large and heavy. If they ever develop some magic zeolite for solid state storage maybe the tanks can have reduced pressure but it most likely won’t happen in the next 30 years.

For the next 20 years figure on biodiesel, ehtanol and butanol as your best bet for renewable aviation fuel.

It’s a lot tougher than replacing fossil-fuel-powered trains, cars, and ships. Because of the excellent energy density of kerosene.

I think in 2025 the airship idea will see a revival with lots of new innovation. Photovoltaic-powered planes carrying 300 people are difficult to imagine.

I will be possible for one pilot next year to fly around the world, see

http://en.wikipedia.org/wiki/Solar_Impulse_project

http://www.solarimpulse.com

I could imagine that in 2035 we will have solar-powered orbiters that don’t take off and land and just keep flying around the globe using the jet stream. Helium and water/steam based airships will shuttle between airports and these orbiters. Next stop New York. Next stop Boston. Next stop London. Next stop Frankfurt. And so forth.

Dead cats cause global warming. It’s a fact.

It’s untapped because of its greenhouse gas effects! Didn’t you read the really super accurate scientific reports on this?

Dead cats ate mice.
Mice ate grain.
Grain stored carbon it took out of the air.

Dead cats don’t drive cars powered by dead plants rotting away 250 million years ago.