Re: Tidal?
You could put floating waterwheels on many rivers.
These are anchored but can rise or fall with river levels.
These would use the flow of water to turn the wheels. As the majority of rivers flows 24/7/52 then there is always a flow of power.
These could be placed under bridges (where the water speeds up) or at the sides in multiples
It wouldn't take an enginnering genius to get a design that could be mass produced thus lowering the cost.
Ok, so it might not be in the mega or goga watt range but as the tesco advert says
'Every little helps'.
Just think what a thousand of these on the River Thames/Severn/Trent might produce?
Maintenance? just lift them out of the water, replace with another one and cart the old one off to a base for work.
But hey, I'm just dreaming. The planners would put a stop to this sort of thing in an instant.