Wave Energy
We will be hearing about niche applications of renewable energy until hell freezes over, and I have no problem with that. Having said that, I do object to developers of these technologies who claim that energy that is extracted from waves, river and ocean currents, the heat buried within the Earth, and solar thermal are, in general, economically competitive with wind and solar PV.
As presented here, wave energy makes sense in a few coastal regions of the world where fossil fuels are expensive to import, and solar and wind conditions are particularly bad.