[_heimdall]

Sure, nuclear may fit the bill. That avoids needing a new advancement if we're happy enough with the environmental impact of nuclear generation, but it doesn't avoid all the external costs beyond just the nuclear reaction.

Reactors themselves take a large amount of resources, some rare, to build. Infrastructure is another huge resource suck, all that copper has to come from somewhere. Nuclear has the nice benefit of being on-demand, so it does at least dodge resources needed for energy storage.