Quote Originally Posted by Crocodile
Quote Originally Posted by Johanna
I am not aware of any clean low emission way of flying. Can you tell me about it?
How much cleaner is it than, say, a normal Boeing 707?
Basically, the only by-product (=the pollution) of the hydrogen oxidation is water. Can it be any more clean?
It's not that simple. Large amounts of water vapor may change the weather patterns the same way today's CO and CO2 do.
Heavy clouds - nearly 100% humidity, etc...

Presently, the most common way to produce hydrogen is to extract it from water by means of electricity.
And you spend more energy on producing hydrogen this way than it will produce when burning in oxygen.