It was interesting realizing that a lot of our power is still, at its core, a steam engine
We discovered a banger like 400 years ago and have held on tight until right about now with wind/solar/hydro.
Still going to be using them geothermal/fission/fusion for at least another 100 years though.
Hydro is just more dense steam, wind is less dense steam, it’s steam engines all the way!
The only really new kinds are thermocouples (mostly garbage) and solar panels (poor efficiency, but abundant fuel).
Some fusion might end up using magnet pumping, which is basically just a plasma powered piston.
There’s also fuel cells, where fuel is not burned to create steam to move something, but combined with oxygen in a different way (the end products still being the same) so the electrons shuttled around during this reaction can be utilised as electricity. Think of combustion as oxidation of your fuel, the oxidation meaning that you (among other things) move electrons from the fuel to oxygen. In combustion, unfortunately you can’t access the electrons directly, as they are always stuck in the chemical bonds of the molecules, that’s why we take the detour via heat/mechanical - the steam engine. The fuel cell now separates fuel and oxygen, and thus divides the combustion reaction into two parts that happen at opposite sides of the cell. Those sides are divided by a membrane that does not allow the electrons to transfer across, so they need to take a detour through an electric circuit, in which we can harvest them as electrical power.
I always found it really fascinating that fuel cells are the only other technology than solar where the electrons we use as electrical power are more or less directly generated as opposed to the detour via a generator. Unfortunately, fuel cells are still a very niche technique.