There was a lot of "outstanding inventions" of cheap energy. None of them give anything interesting. Even hardcore replicators like J.P.Naudine get nothing.

IDK, in all that stuff the most annoying thing is "inventors" themselves, really. Talking about "saving world" they somehow leave worst possible documentation, if any.

Meanwhile, any energy we could have is eventually from our Sun. From obvious solar panels to even nuclear. Every single kind. So, with high probability any new energy source will be also solar. :)