We still rely on steam engines....in a turbine form, to push our nuclear ships and subs. If their systems could be miniaturized....
They can. They still have the problem of taking time to build up a head of steam. (That expression actually means something).
We use gas turbine engines to power ships, airplanes, and tanks. They take a little longer to start than piston engines, but the difference isn't nearly as great.
Power plants for energy. Steam. We still use it massively. Saying “nuclear” or “oil” or “coal” is just the fuel to heat up steam.
Steam engine is the greatest invention ever IMO. Massive change due to them.
Our NUCLEAR ships? Technically, I suppose Nuclear propulsion is steam-based, but I’m thinking getting regulatory feasibility might be tough.