Have you ever seen a tidal inlet wave, this is where the wave goes from low tide to high tide and travels up a channel, river or inlet. If these waves happen every day at the changing of the tide, then we can collect that energy. If we are very smart about how we collect that energy, we can store the energy we collect and use it throughout the day. I would like to take your mind to a place that you perhaps haven't thought about before even if you have studied ocean wave generation technologies. Let's talk.
You see, many people do not see the potential here for tidal inlet waves, but I certainly do. It is quite possible that you could create a plow system on a long cable that the inlet wave could push thousands of yards if not miles. You might also build a sub channel where the tidal wave energy pushes the water in a channel built parallel to the river, or one which goes off on a "Y" with multiple fingers. Those fingers could get smaller and push the water into elevated water reservoirs.
The water in those reservoirs could be let back down to the level of the river as needed with small hydro-pumps along the way collecting that energy using the dynamic pressure of the water, just as hydroelectric power plants do. In essence the reservoir would be like a battery saving that kinetic energy until you wished to harvest that energy and allow the water to flow back into the river. Meanwhile you could use the energy and allow the water to flow out until which time the next tidal inlet wave were to occur.
In this case, one could ask; why hasn't anyone done this yet? Is it because the land near rivers is too valuable? No, I don't think so, that may be the case in some places, but certainly not all. Is it thought that that water doesn't move fast enough for there is not enough energy behind it? I doubt that because there is quite a bit of energy behind that tidal inlet waves, in some rivers it is incredible in fact. I'm not suggesting we do this where the tidal wave is not predominant, I'm suggesting we go to those places where it is a force to be reckoned with, and collect that energy and use it.
As far as I'm concerned ocean wave energy is the most renewable and sustainable energy source we could ever hope to use. First of all we know it sustainable because ocean waves have been going on for 4.5 billion years as far as we know. That's a lot of dynamic pressure, and it is as old as the moon which orbits our Earth. Why wouldn't we be using it, harvesting it, and taking advantage of this resource? Please consider all this and think on it.