I'll start by pointing out that as yet I know nowt about how this idea is to be constructed, but I do know about SW gales! :roll:
If these devices are to be secured to the sea bed I would ask how they will accomodate the occasional extreme wave, those same waves that have been suggested as sinking super tankers so rapidly that no SOS was sent.
Despite what most people believe sea waves do not move water, untill the sea bed shallows and the wave in effect strikes the bottom, thus logic suggests that theses devises could not be used in shore, if they were I concur with Roger M.
Thus far, AFAIK, the tests have only been conducted in the Thames.
So far, all the green alternatives have produce more heat than light!