As I said in  today's Guardian newspaper;

"According to the world offshore wind report 2008-2012, published a week ago, only 4.5 GW will be installed in the whole world over that period. Maybe the government should have paid attention to the supply constraints the report highlights before it takes a stand on something it can't possibly deliver. The government is deluding itself on a grand scale. There will be no race by investors to build offshore wind farms - the returns are just not high enough and there are supply-chain constraints in installation vessel capacity and insufficient turbines."

The world offshore wind report by the way, is available here from Douglas Westwood Ltd.

Right now, there's only 1.1 GW of offshore capacity in the entire world. That compares to a global onshore wind capacity of at least 75 GW as at the end of 2006 , which you could probably easily inflate by another 15 GW for 2007 so far.  Basically then, offshore wind constitutes just over 1% of global capacity - no great shakes.

And the vessels to put these offshore wind turbines are rare and extraordinary looking beasts . . . for the techy detail on this boat, the Mayflower Resolution, see here, built in China. As you'll see, it stands on stilts which can only take it out to a depth of 45 metres or so. That actually rules out a lot of windy sea. Nevertheless, there is a long queue to rent out this ship.

My final thought about offshore wind is that the turbines are just not big enough to be economic. Plans have been made for a 10 MW model and theoretically, 20 MW is possible using today's technology. But that will probably require an installation vessel twice the size of the Mayflower. One more technological shift in increasing the strength of the blades and reducing their weight would be a huge breakthrough.