Eh. Hate to be a killjoy, but I'll believe it when it happens. The concept of a Tidal Harness has been around for decades and we've done exactly jack shit with it and kept burning oil happily.
There's an interesting historic lesson you can take from Hero of Alexandria. One of his inventions was basically a steam engine. It was a hollow sphere with two spouts pointing in opposing directions, suspended by a bar off the ground. When water was poured into it and a fire was put under it, the water would boil and rush out as steam from the nozzles, causing it to spin. Hero, by all other counts a genius, never went any further with it and it was basically just considered a toy and curiosity; the "leap" from this phenomenon to harnessing it for power was never made. A half-step away from steam power, thousands of years ago.
A theory I heard that's both fascinating and a bit grim is that it wasn't that he didn't realize the potential; but that he saw no need for it. His civilization at the time had enough slave labor to build and power any work of architecture imagineable. With all the manpower, there was no want for energy.
A superior energy source, or even just a superior method of doing something, can be completely ignored if things are currently copacetic. Until whatever's been propping people up runs out entirely and the panic sets in.
