Modern — overdeveloped — societies in the West are already in a severe crisis. Something, which will eventually turn into a long global emergency in the years and decades ahead. A five centuries long era of economic growth — ushered in by colonization and leading to the plundering of natural, mineral and most of all fossil fuel resources —
Yep, even nuclear reactors use some form of steam engine to generate electricity out of the heat they produce. It’s remarkably effective.
But of note to OP is that steam engines aren’t necessarily unsustainable. The heat to produce motion that generates electrical current can be generated by renewable means. Molten salt solar basically does that, for example, and it fits most definitions of “sustainable”.
What types of electric generation that aren’t heat related? I can think of wind and solar, and hydro? But nuclear and fossil fuels are steam, aren’t they?
You answered your own question - correct on all counts! 😊 There are really very few physical principles to base power generation technology off to begin with; it’s all going to come down to either inducing a current in a conductor by spinning a magnetic field (molten salt solar, nuclear, fossil fuels, hydro, wind, and anything else involving a turbine at any point all operate on this principle), or inducing a current by futzing with quantum mechanics (photovoltaic cells alone operate off this principle, as far as I understand such things - and I understand just enough to know I understand nothing at all).