Offshore wind will reach 70.1 GW of capacity by 2017, says Pike Research. That's 17 times its current capacity, which is 4.1 GW, and amounts to several times the current maximum solar capacity of the most solared-out country in the world, Germany.
Europe is currently in the lead on offshore power, but by 2017, China will pull even. (The U.S. will be in the mix somewhere too, if we can get those Nantucket swells to settle down.) We’re mostly talking about ocean wind farms, but a portion of this new capacity will come from freshwater offshore installations, such as in the Great Lakes.
Currently, offshore wind power is still 2-3 times as expensive as on-shore wind, but it's getting cheaper. Some of the world's steadiest, strongest winds are offshore, so it seems inevitable they'll be an important part of any renewables mix.
Offshore Wind Power Capacity to Boom in the Next Six Years, Pike Research.