Need More Energy? Look to the Islands
6 Jan, 2009 09:02 pm
Islands offer many advantages for hosting wind farms without the problems of mounting wind turbines in a hostile marine environment.
The U.S. Department of Energy (DOE) estimates that more than 900,000 megawatts (MW) of wind generation capacity—roughly equivalent to the current amount of total installed electricity capacity for the entire country—exists within 50 miles of the country’s coasts. The largest areas of Class 7 wind power, the strongest class, in the United States are located in Alaska, with regions (in the Aleutian Islands) containing winds with exceptionally strong speeds. Of course, much of this distantly located wind resource cannot be usefully harnessed or transmitted to load centers, but the U.S. hosts several offshore sites on the east coast that contain wind resources of Class 5 or higher.
Why do the numbers of estimated offshore wind potential appear so good? Offshore wind turbines can harness stronger, more consistent winds than those that course through mountain passes or across open plains. Moreover, offshore wind farms may be able to utilize more efficient and larger blades, exploiting the basic physical laws governing wind turbines that provide huge economies of scale for long blades.
From a policy perspective, offshore wind turbines may have other advantages. The best technically designed—and largest—turbines often run into opposition by landowners who object for aesthetic and practical reasons. The biggest turbine blades sometimes interfere with beautiful viewscapes and make disturbing noises. Rather than try to site these behemoths near population centers, they can be located in the sea, thus avoiding “not-in-my-backyard” and other local concerns.
Despite these potential advantages, offshore wind farms face significant obstacles. Most important, offshore wind turbines cannot be used in waters deeper than around 30 meters, significantly impeding the amount of wind resources that can be exploited. Because this limitation requires offshore wind turbines to remain relatively close to land, they often face serious public opposition, as has been the case with proposals for wind farms proposed near Long Island and in New England. Some concerned citizens contend that offshore wind farms mar the natural beauty of the coastline, interfere with fishing, diminish property values, damage recreation and tourism, and harm marine wildlife and migratory birds.
Meanwhile, researchers still need to address a host of technical problems dealing with anchoring turbines in the seas, and they need to deal with novel and sometimes unique environmental and logistical problems. Though free of habitation from humans, the seas have great commercial, military, and recreational value that requires careful negotiation between developers and a host of stakeholders.
The DOE notes that the U.S. experience with construction of deep water-based turbines that can harness high wind speeds is “literally nonexistent.” Few (or no) projects have yet incorporated alternative substructures such as foundations, floating platforms, and anchoring. Moreover, little research has been conducted on lightweight materials that can handle wave and ice loading. Though Europeans have built several offshore wind projects, lessons learned from their efforts do not generally apply to the United States, where deeper waters, higher wind speeds, and more severe turbulence complicate design and construction.
The use of wind turbines on islands, however, may help overcome some of the obstacles that hinder widespread use of offshore wind resources. Island wind farms could help harness the greater wind speeds in the ocean while reducing the expense of constructing, mooring, and stabilizing offshore turbines to the ocean floor. Moreover, they would help escape public opposition directed towards near-shore wind farms, especially if the islands are lightly populated or deserted, and they would be less susceptible to severe storms and weather events. Of course, the picture isn’t totally rosy. After all, bringing the island-produced electricity to the mainland using underwater transmission lines will face technical and economic challenges. Still, the approach deserves serious consideration.
Excluding Hawaii and the small land masses in the Great Lakes, the United States is home to around 1,300 islands, roughly half of which are uninhabitable or unpopulated. These unpopulated islands constitute around 0.003 percent of U.S. land area, or approximately 10,612 square miles, with a high concentration of islands off the coasts of California, Washington, Alaska, and New England.
By hosting wind turbines on islands, developers can gain the advantage of huge offshore wind resources without the difficulty of building turbines in shallow or deep-water environments. Most obviously, the country’s extensive experience in building land- based turbines could be more easily adapted to islands, since the land masses would serve as platforms for wind farms. Focusing on islands would also avoid the need to conduct extensive surveys of the seabed and ocean floor. They would also minimize requirements for performing studies of the interactions of turbine materials with subsurface materials, marine biology, and the ocean current. Finally, placing wind turbines on remote and uninhabitable islands (or islands that are not visible from the coast) would help deflect public opposition to objectionable (in some people’s opinions) viewscapes.
However, several development challenges must be overcome if island-based wind energy systems are to find greater use. These challenges represent opportunities that researchers in the United States and elsewhere can address. In particular, investigators could focus on a specific niche of wind-turbine technology—that of relatively small-blade designs that can exploit Class-7 winds in a corrosive environment. Moreover, related studies of complementary energy technologies, such as those that take wind-produced electricity to make a form of storable energy, such as hydrogen, will require special efforts. Finally, social scientists need to perform more detailed economic and political analyses of these proposed energy systems. Though this engineering and social-science endeavor may seem ambitious, the benefits appear equally significant.
For Further Reading
Benjamin K. Sovacool and Richard Hirsh, “Island Wind-Hydrogen Energy: A Significant Potential U.S. Resource,” Renewable Energy 33(8) (August, 2008), pp. 1928-1935, available at linkinghub.elsevier.com/retrieve/pii/S0960148107003825.