Offshore wind

Bruce Nichols

February 1, 2013

Ocean energy is not just in the water. There’s offshore wind, which tends to be steadier than onshore wind. But turbines are harder to build and maintain in a marine environment than they are on land. The Bureau of Ocean Energy Management (BOEM) estimates theoretical US offshore wind potential is four times current US power output, although practical recoverable power will be smaller.

Entrepreneurs have taken notice. One company, Bostonbased Energy Management, plans to start building what likely will be the first US offshore wind farm later this year. The company envisions a 130-turbine, 468MW capacity, 65km2 facility in Nantucket Sound and already has pre-sold three fourths of the power.

Other companies are waiting in line, and the US Department of Energy is trying to help with challenges that include stiffer permitting requirements and higher capital and operating costs than onshore wind operations.

DOE recently awarded grants to seven projects on the Atlantic, Gulf and Pacific coasts. Among them is Seattle-based Principle Power’s plan to build a truly oceanic wind machine, a floater that does not have to anchor on the bottom in coastal waters like virtually all its predecessors (pictured above right is a prototype which has been operating offshore Portugal since October 2011).

As with wave and tidal energy, the UK is the world leader. The world’s largest offshore wind farm, the London Array, is in the outer Thames Estuary. It was declared finished in December 2012 upon installation of the 175th turbine (pictured below). The London Array started generating power last October and is due to be running at maximum capacity of 630MW – enough for 470,000 homes – this spring.

The London Array was built by UK-based E.On, Abu Dhabi’s Masdar and DONG Energy, based in Denmark, the nation that pioneered offshore wind in 1991.

An even larger UK offshore wind project, Dogger Bank, is being developed in the North Sea, off the coast of Yorkshire. The ultimate goal is huge, 9.6GW, equal to nearly 10% of UK power demand, by 2020. Cost estimates have not been disclosed.

Dogger Bank is being developed by Forewind, a consortium of UK-based SSE, Norway-based Statkraft and Statoil, and RWE power renewables – the UK subsidiary of the German renewable energy company RWE Innogy.

“There’s a lot of public support for renewable energy in the UK and for offshore wind in particular,” says Lee Clarke, Forewind director and general manager. “The UK government has really got behind finding ways to exploit this fast renewable energy source off our coasts.”