Hydrogen planes

[BBHighway]

At some point, when we have all the ground transportation problems solved , we'll need to figure out what to do about aircraft. Most likely, batteries will always be too heavy for airplanes. I've always thought that's where hydrogen can finally find its place. Even for that application, hydrogen may lose out again to biodiesel.

[Cobos]

I've also got some hope for H2 as a airplane fuel. Cryogenically frozen H2 is very energy intensive to freeze, but it is safer than compressed H2. And for airial applications you care more about high power/kg than about efficiencies since the freezing might be done with renewable sources.
They say that any CO2 emmitted up at flight height is a lot worse than the same amount emitted by cars at ground level, so that goes against biodiesel in the long run. On the other hand water vapour is also a strong climate gas so I suppose emitting lots of it right there in the atmosphere might not be a good idea either

Cobos

[BBHighway]

Water vapor is has a greenhouse effect that is about 20 times stronger than CO2, but while CO2 stays in the atmosphere for 100's of years, water vapor tends to condense out as rain in only 30 to 60 days or so.

That makes the cumulative greenhouse effect of water vapor just a tiny fraction of CO2.

[TEG]

Another thing about commercial aircraft is that they are trying to fly them all the time, and so they tend to refuel just before taking off. As with rockets you could consider having a fuel that is stored at a special temperature because you know you will use all the fuel soon after refueling. They all have a fixed distance flight plan so you can add just the amount of fuel you plan to use.

Private aircraft and cars, on the other hand, need a fuel that can sit in the tank for long periods of time between use.

[Cobos]

Water vapor is has a greenhouse effect that is about 20 times stronger than CO2, but while CO2 stays in the atmosphere for 100's of years, water vapor tends to condense out as rain in only 30 to 60 days or so.

That makes the cumulative greenhouse effect of water vapor just a tiny fraction of CO2.

Don't get me wrong I do know that, I've actually taken a small University course on our atmosphere (not that I passed, it seemed I needed to study for 3 days not 2 as I did

The point I was making was that down on the ground a water vapour exhaust is fine as it will condense almost immediately and have almost 0 effect on the climate. Hence why a H2 fuel cell car has no harmful exhaust. For a plane on the other hand it might be different since the water vapour WILL have an effect on the climate and thus the advantage of H2 compared to organic combustion might not be as good. I don't have any data on that.

Cobos

[doug]

I'd think that one could easily design a condenser into the plane. Especially since it's cold up there. Then the plane could dribble liquid water out of the exhaust instead of vapor.


I should point out that water vapor is a normal byproduct of combustion. So standard aircraft are already putting water vapor up in the atmosphere, as well as generating contrails.

[doug]

An actual H2 fuel cell plane:
Boeing fuel cells up in the air - AutoblogGreen

[dpeilow]

On the subject of hydrogen planes - both H2 powered jets and fuel cell powered light aircraft have been demonstrated. The main issue is storing enough hydrogen to make practical flight times.

DASA, one of the founder companies of Airbus, looked at this in the 90s with their cryoplane project.

Is there a cryoplane in our future ?

[doug]

An actual H2 fuel cell plane:
Boeing fuel cells up in the air - AutoblogGreen