Arthur Clarke once commented (brilliantly, I think) that humans are over optimistic in the near term and under optimistic in the long term.
I don’t think a sufficiently advanced culture would have much use for huge amounts of energy. I think the definition of “sufficiently advanced” would eliminate such a need. Any research objectives might well be accomplished with with far more modest amounts of energy.
Just an opinion.
Agreed—nanotechnology on a massive scale could be indistinguishable from nature.
That is one of many reasons why SETI is a pathetic joke.