Originally Posted by
jantar99
Energy density per kg and per litre are important in aviation.
Which, according to
https://hypertextbook.com/facts/2005/MichelleFung.shtml and
https://hypertextbook.com/facts/2003/EvelynGofman.shtml is better for hydrogen.
Storage and safety are legitimate concerns, which is why I mentioned "working on a safe way"
The effect of water emissions at high altitude are not so great in terms of contrails, that is indeed what some studies have suggested. However, the water formed by hydrogen combustion might just freeze and fall to the ground. I'm not saying that this is happening, I'm saying that it would be worth studying.