Turning Great Lakes wind into energy

Late this summer, Denmark inaugurated the world’s largest offshore wind farm, Horns Rev 2. Located nearly 20 miles from shore in the North Sea, the 209-megawatt wind farm consists of 91 turbines that together will generate enough energy for 200,000 households a year.

Closer to home, amid a growing interest in shifting from nonrenewable to renewable energy sources, the Great Lakes are attracting attention of their own as potential sources of wind energy. Ohio is currently working toward developing a pilot wind project in Lake Erie, while Ontario, Canada is seeking to develop projects in both Lake Erie and Lake Ontario. Meanwhile, Wisconsin is beginning to look more seriously at Lake Michigan’s wind-energy potential as the state works to meet its legislated goal of producing 10 percent of its electricity from renewable sources by 2015.

But while offshore wind as an energy source has advantages-it’s cleaner and consumes much less water than fossil fuel sources, and has the potential to produce more energy than land-based wind-it also will require addressing various environmental, technical, economic, and legal issues.

“[Great Lakes offshore wind] is an idea that’s worth considering. It has pluses and minuses-and agencies, industries, power producers, and customers will have to figure out if it can be done with more pluses than minuses,” said Steven Ugoretz, an environmental analysis and review specialist with the Wisconsin Department of Natural Resources (DNR). Ugoretz also served on a workgroup that produced a report earlier this year for the Public Service Commission (PSC) on the feasibility of offshore wind in Wisconsin.

Spawning Grounds

When it comes to aquatic resources, one of the top concerns related to Great Lakes wind energy is how wind farms might impact fish and fish habitat. Thus far, wind farms have been built only in marine environments, so solid information on how freshwater fish might interact with wind facilities is largely lacking. “It’s a big question mark,” said Jill Utrup, a biologist with the U.S. Fish and Wildlife Service (USFWS).

However, experts have identified a number of factors they think will be important to consider as potential wind farm locations are evaluated. One of those, according to the PSC report and a recent report from the Great Lakes Wind Collaborative (GLWC), is whether the site is a critical spawning area. Lake Michigan’s mid-lake reef, for example, has site potential from an engineering perspective, but it is also an important spawning ground for lake trout, a fish the DNR and USFWS are working to restore.

“It’s probably not a good idea to put these things where the trout are spawning, simply because we don’t know what the impacts would be,” said John Janssen, a scientist at UW-Milwaukee’s Great Lakes WATER Institute (GLWI) who studies the mid-lake reef. “We also don’t know what else might be spawning [at the mid-lake reef],” he said. “When we go over the reef with sonar, it seems to be a busy place, but we don’t know what it’s busy with.”

Utrup said that conducting surveys to identify important fish habitats can help minimize adverse impacts from wind farms. Surveys of breeding habits for birds and bats have proven useful for land-based wind projects, she said.

In areas without spawning habitats, wind farms would likely have less potential to adversely impact fish. In fact, wind farm structures might serve as spawning habitats in such areas and therefore actually have a positive impact, according to the PSC report.

Other Aquatic Issues

Another aquatic concern related to wind farms, cited in the GLWC report, is the potential for scouring of the lakebed by currents flowing around wind-turbine foundations. Scour could be beneficial or detrimental, said Janssen. It might expose more rock, thereby providing more spawning habitat for fish like perch, he said. Or, the exposed rock might act as an “attractive nuisance”-meaning fish might be drawn to spawn there, only to have their egg masses broken up by currents.

Other factors that could adversely affect fish-and therefore should be minimized or avoided-include noise and vibration from wind farm construction and operation, and the re-suspension of contaminated sediments during construction, according to the PSC and GLWC reports. Additional impacts that are harder to anticipate and detect in water than on land could also occur, cautioned Janssen.

On the plus side, wind farms could serve double duty as monitoring stations that would help scientists track fish and collect lake data, said Val Klump, GLWI director and scientist. “If we build these, we should build a monitoring network into them,” he said.

Overall, said Klump, “while offshore wind poses a number of technical and environmental challenges-like locating the structures to avoid habitat and ecological disruption-it also avoids some of the problems faced on land and has some real advantages. Given our increasing demand for energy, it’s definitely something we should be investigating.”

Jennifer Yauck is a science writer at the UWM Great Lakes WATER Institute. GLWI (glwi.uwm.edu) is the largest academic freshwater research facility on the Great Lakes.

• View the PSC report: psc.wi.gov/globalWarming/05EI144/index-WindonWater.htm.
• View the GLWC report: glc.org/energy/wind/pdf/Siting-Principles-and-Guidelines-for-Wind-Development-on-the-Great-Lakes_FINAL.pdf.