[Piwoslaw]

I watched a vid or 2 recently about tidal power.
And there are places on Earth where due to the natural landscape the flow is already pretty decent without additional damming (the constuction of which would upset the environment and use resources), e.g. Ireland and eastern Canada.

Also, experience has shown that the sound made by the underwater machinery is enough to keep many sea animals at a safe distance, reducing the sushi production. One project mentioned sensors which slowed down the turbines should any whales, etc., approach too close. Whether it is to save marine lives, or save servicing of damaged equipment, still a gain.

What I haven't come across (mostly because I haven't searched) is whether the marine environment is more or less harsh on the hardware than on wind turbine, hydro plants, etc.