Both would be awesome (though unlikely). I was thinking more of nuclear fusion, as we technically have the tech just not the financial backing to build the plants. There was a guy what, a decade or two ago that had all the math and proof of concept figured out, even a mostly working prototype. They were looking for more funding, needed 100 million or so to build a fully functioning plant.

As I recall it was all shut down by the existing nuclear energy commission. They trash talked the project as they need all the funding for the mammothly huge fission plants.

Fusion plants are a fraction of the size, are comparatively inexpensive, and generate a fraction of the waste material. So obviously we shouldn't have it. 🙄