Technology

Offshore wind power gaining strength

 By Robin Wylie

Offshore wind represents one of the largest sources of untapped energy on Earth…

(Click on to enlarge the infographics below)

The waters along the coast of the United States alone have an estimated potential wind power yield of 2000 GW—approximately two times the combined generating capacity of the country’s electric power plants.
Winds at sea tend to be more powerful and consistent than those on land, and, while construction and power transmission are more challenging offshore, the space conflicts associated with onshore wind turbines are significantly reduced. This potential led the International Renewable Energy Agency (IRENA) to list offshore wind in third place in its Innovation Outlook arrangement.
Offshore wind is currently lagging far behind onshore wind power in terms of installed capacity, however, the offshore sector has seen impressive growth in the past 15 years, and seems poised to play a much greater role in renewable energy generation in the coming years.

Sheringham Shoal offshore wind farm, England (Harald Pettersen/Statoil, Wikimedia)

So far, the majority of the world’s offshore wind installations are located in Europe. Since 2002, when Europe’s first business-scale wind farm came online in Denmark, the continent’s installed offshore wind capacity has grown from approximately 250 MW to around 12,600 MW.
The United Kingdom makes up the largest share of Europe’s offshore wind capacity, with 41 percent (~5200 MW), followed by Germany with 33 percent (~4100 MW) and Denmark with 10 percent (~1300 MW).

The share of offshore installations in Europe’s wind energy market is still small—representing around 8 percent of the continent’s approximately 154 GW of installed wind capacity—but its growth spurt shows no signs of slowing. According to estimates by WindEurope, a major wind advocacy group based in Brussels, approximately 16,000 MW of additional offshore wind capacity are set to go online in Europe by 2021, which would bring the total installed capacity to approximately 29,000 MW. An additional 65.6 GW of projects are currently in the planning phase.

Aside from Europe, which accounts for 88 percent of the world’s offshore wind capacity, China is the most significant emerging market, with around 11 percent of global installed capacity.

But the United States could soon join the pack. Its offshore wind power program is still in the very early stages of development—to date, the only operational offshore wind farm in the U.S. is the 30 MW Block Island Wind Farm, located off the coast of Rhode Island—however numerous offshore wind projects are at the planning or construction stage, suggesting that the European boom in offshore wind could soon be emulated across the Atlantic.
The US Department of Energy has allocated around $200 million since 2011 for research, development and demonstration projects for offshore wind. Permits have also been granted for a 24 MW offshore wind farm in New Jersey, and a 468 MW project in Nantucket sound. A project is also under development off the coast of Point Estero, California, which with a proposed capacity of 650 MW, would be the largest offshore wind farm on Earth.
Another offshore wind project, currently at the proposal stage, could set the bar even higher. If given approval, Bay State Wind, an offshore wind farm backed by DONG energy, located 15 miles off the coast of Martha’s Vineyard, could have an installed capacity of up to 1000 MW.

Offshore wind may represent a huge potential source of renewable energy around the world, but harnessing it is far from trivial. Offshore wind turbines can face significantly harsher conditions than land-based turbines, with storms, waves and salt spray corrosion leading to higher failure rates of turbine components. Costs are considerably higher for offshore wind because of the additional cost for foundations and connection of the offshore wind parks to the grid. The price per megawatt-hour is now between 73 and 140 Euros ($83-159) for offshore wind, compared to 50-96 Euros ($57-109) for onshore wind and 65-70 Euros ($74-79) for gas and coal.

But the price of offshore wind power has been falling—by around 50 percent in the last few years—and the construction of larger offshore wind farms, such as those planned in the U.S., is expected to lower them further.
Recent technological advances could also help expand the offshore wind market. The most important of these are floating wind farms, which have the potential to allow offshore wind farms to be situated in much deeper water. The world’s first floating wind farm, a 30 MW wind farm in Scotland, is set to be operational by 2017.

A semi-submersible type floating offshore wind turbine foundation (Untrakdrover, Wikimedia)

By 2030, the offshore wind market is anticipated to achieve 100 GW of aggregate introduced capacity. With the promise of bountiful supplies of untapped energy, coupled with its strong green credentials, onshore wind looks set to become a significant presence in the world’s energy development in the near future.

about the author
Robin Wylie
Freelance earth/space science journalist. Currently finishing off a PhD in volcanology at University College London.