So I've been giving this some thought, and I think I'm going to settle on "won't implement". Specifically, 1) I don't want to start getting into a thing where I'm having lots of individual requests for different fluids from different mods, and 2) IMO, Hydrogen as a fuel source goes kind of out of scope for this mod (kind of... it's a fine line).
That said, there are still ways to have this, just not officially through this mod. When I have some time this weekend, I'll write up some info and post it into a FAQ. Once done, I'll post back here to make you aware (if you have notifications turned on).