This tidal turbine is located in Strangford Lough.
It can only power around 1,000 homes apparently.
It is still only a prototype, but all the same, unless these things can be made a lot more efficient, we are going to needing tens of thousands of these things before all the fuel oil runs out!
As you can see from this photo (and some of the other tidal turbine photos) the actual turbines of this tidal turbine are not even in the water a lot of the time.
I am guessing that this will reduce the energy generating potential of the equipment somewhat!