The nice thing about this example is that Heinlein makes clear that this technology is a really really big deal that has totally transformed technology and made the people who control the technology the masters of the world.
Sounds to me like Gil’s lightning-scepter.
Shipstones were just storage devices, an ultra-dense battery. Solves the distribution, but not the generation problem. Heinlein, as he nearly always did, postulated a whole bunch of consequential changes from this (independent households possible even in wilderness areas since they’re off the grid, different transportation possible due to virtual fuel independence, infrastructure changes since roads and transmission lines are essentially obsolete) but the things still needed to be charged somewhere.
Environmental damage would be localized since you could build enormous facilities with no need to spread them out in nodes, and the power plants would automatically be more efficient since there would be no transmission losses. Big changes, but not paradigm changing. I don’t remember if the power plants were mentioned, but even if he didn’t have fusion plants in the story, Heinlein wasn’t afraid of nuclear power; he’d just postulate the most efficient way he could think of for dealing with waste.