Runs off water! We actually use a modified diesel engine. We want cone heads, to increase the maximum pessure from 8 atmospheres to 10! This is a veery little change. We spray water drops into the cylinder, and it does MNF
A diesel does a bit of Molecular Nuclear Fusion today
The way to double the power of a diesel engine, is to Ti plate the cylinder body and pistons. This will increase 'r' by a factor of 2.
So we inject our regular water into the engine. And get out a whiff of helium and ozone – as today from a diesel engine. So no Fossil Fuels burn, nd no CO2.
We can use standard river water – we didn't get around to trying salt water. In principal, it should not matter – except salt does tend to erode the engine. Better off with distilled.
So no petrol or diesel burn, and no expensive trip to a garage for fuel.