It makes sense in the UK at any rate, what with us being an island and all.
I think there's an island in the highlands that's powered by tidal.
(
Smallbrainfield,
Thu 31 Mar 2011, 13:46,
archived)
There's one in France
that's been on the go almost 50 years, and generates 600GWh per year.
(
sandettie light vessel automatic New Twitter - @bollocksreally,
Thu 31 Mar 2011, 13:51,
archived)