What sci fi movie (could have been a "TV" movie) was set in a cavern & dealt with electricity generation?
The struggle in the movie was "cowboy inventor dude" vs "evil corporation". Protagonist is a Robert Redford like dude maybe?.?
It might have had something to do with the sonic properties of the cavern harmonics?.?
I believe there might have been some large "Tesla coil" style lightning special effects during the destruction of the invention (but I could be conflating different movies together.)
Maybe in the 80's?.? (or late 70's / early 90's)?