Energy diversity is not a feature intrinsically. Cheap, dispatchable, reliable, scalable energy enables maximum flexibility. In the real world this means nuclear fission.
"Cheap, dispatchable, reliable, scalable" are all functions of the environment. If the environment changes so do these values (for this and all other energy sources).
Nuclear is superior in all rational aspects (for use on Earth). Only in the irrational (unscientific regulation) can other sources be more efficient.
was it superior in the 1800s?
Researching other energy sources is fine, but keeping them alive artificially after proven inefficient is wasteful. Of course people are free to waste their own money if they like.
