Not quite a reply to your above question, but remember that hydrogen + oxygen = heat + water. However, as there is still a lot of money to be made from oil by greedy people, that kind of fuel is still a way off. For that reason, I am a bit of a conspiracy theorist as far as non-fossil fuel engines are concerned. I believe there already have been such inventions which have been quickly eliminated. Have a look on You Tube for hydrogen powered engines.

Hi 27 vet
Your comments are in keeping with many honest opinions about why ‘Detroit’ (and all global auto engine manufacturers) have really stayed (making bucks) with the internal combustion engines.
The same is true of aero engines.
I still believe that rather than my write a 12,000 word dissertation about Scottish Nationalists’ Politically correct gobbledegook about in/under sea Wave Machines and Wind Turbines (the medium to long term maintenence of which far outweighs any short term energy gains), I ‘d rather write something on a subject passionately close to my heart – aero engines of the future using less or non-fossil fuels.
I shall look as you sugegst on You Tube – Thanks