Governments and electric utilities worldwide are pursuing offshore wind generation as one of their strategies for meeting renewable energy objectives. Ironically, some projects are being held up by environmental concerns, particularly in North America.
According to renewable-energy consultancy BTM Consult, 3.16 gigawatts (GW) of offshore wind generation were operational worldwide as of October 2010, with 75 GW expected by 2020. As things stand now, most of the capacity is in Europe; the largest facility is the Thanet Offshore Wind Project in the UK.
- Impulsive noise from seismic surveying and construction pile-driving
- Ongoing operating noise from wind turbines
- Physical damage to the seabed from construction
- Effects of the physical presence of the structure on bird and marine life – for example, marine organisms colonizing structures or birds colliding with turbines
- Visual intrusion and negative aesthetic effects of wind turbines
- Chemical spills and atmospheric emissions during construction or maintenance of facilities
- Electromagnetic effects on sensitive species from undersea power cables
(Photo Credit: By Phil Hollman from London, UK. Off-shore Wind Farm Turbine at Kentish Flats [CC-BY-2.0], via Wikimedia Commons )
Push-Back on Offshore Wind Energy
The proposed Cape Wind project, planned off the Massachusetts coast between Cape Code and the islands of Nantucket and Martha’s Vineyard, has generated considerable opposition. The project, now in the permitting process, would construct 130 turbines and produce up to 454 megawatts (MW).
Opposers of the Cape Wind project emphasize dangers to the sensitive environment of Nantucket Sound as a key objection. The Alliance to Protect Nantucket Sound has filed a lawsuit claiming that the project violates multiple environmental laws. The group writes that
Noise and disturbance from the wind farm during construction, operation, and maintenance may result in damage to or loss of habitat, changes in species behavior and usage, increased avian mortality, and overall changes in the Sound’s ecology, including water quality and species distribution.
The Alliance argues that, although the project is moving forward in planning and permits, it is by no means a done deal and can be stopped. The organization writes that the project would have a devastating effect on views from the three land masses. The turbines (440 feet high from the water to the highest blade tip) would encompass “an area the size of Manhattan” and “would be highly visible both day and night from Cape Cod and from the islands of Nantucket and Martha’s Vineyard.”
Energy Management Inc. (EMI), the developer for the project, counters that “from the closest beach on Cape Cod, in clear conditions, the wind turbines will appear one half-inch above the horizon.”
Opposition to a proposed 200-turbine 1,000 MW wind farm by developer Deepwater Wind in the waters off Rhode Island has run into opposition from the commercial fishing industry. To start with, the fishermen were cooperating with planning the project, until Deepwater’s expansion of its plans in late 2010 from the original objective of 100 turbines. The new 200-turbine scope would encroach on prime fishing grounds, the fishermen complain.
Besides the project’s effects on fishing grounds, some of those in opposition are questioning the environmental effects of undersea cables that would carry power to Long Island, N.Y.
In February 2011 the government of Ontario, Canada, declared a moratorium on development of off-shore wind farms pending research on their environmental impact. Projects planned in Ontario involve the Great Lakes; these are freshwater bodies, whereas nearly all projects globally up to now have been in saltwater.
John Wilkinson, environmental minister, issued a statement saying that, whereas scientific research on land-based wind power is extensive, “Offshore wind on freshwater lakes is a recent concept that requires a cautious approach until the science of environmental impact is clear.” Wilkinson recently told CBC News that his ministry plans to study the effect of wind turbines on local ecology and wildlife, as well as how the sounds of wind turbines travel over water.
Texas, the U.S. leader in wind energy, is planning to erect a test turbine by the end of 2011 in the waters off of Galveston. The federal government plans to fund wind-farm studies in varies areas along the U.S. Continental Shelf.
Concerns About Construction and Turbine Noise
The effect of noise on marine life has emerged as one of the key concerns of offshore wind’s critics.
Gero Vella, marine biologist with the University of Liverpool’s Centre for Marine and Coastal Studies, writes that offshore wind farms present two potential environmental concerns, “the noise effect on marine wildlife and the ‘artificial reef effect.’”
Wind turbines, he says, can produce noise along a range of frequencies and intensities. Marine animals vary in their ability to hear noises and in their behavioral response to them. Some species, such as cod, can hear the lower-frequency sounds, whereas others, such as bottlenose dolphin, can’t. For many species, their sensitivity to noise and their response to it simply haven’t been measured.
Dr. Arthur Popper, biology professor at the University of Maryland, and director of the school’s Laboratory of Aquatic Bioacoustics, tells me that he does have concerns about the possible effect of wind farm construction on marine life. But, he points out, “the pile-driving occurs only over a relatively short period of time and is very intermittent.” The real problem, he says, is that
… there are really no data that inform us as to whether the construction sounds would be sufficiently loud to cause behavioral changes in nearby fish. Nor do we really know if the operational sounds would cause behavioral effects. Considerable research needs to be done.
What type of research? Popper responds,
Behavioral studies of fish in the field — not in the lab — to determine how they respond to construction and operational sounds would be of real value. This has to be done comparatively — by this I mean that we need to study responses of a wide range of different fish species, since species differ considerably in their ability to detect sounds.
In an article for Marine Scientist (“Are We Drowning Out Fish in a Sea of Noise?,” May 2009), Popper makes the point that “sound plays a critical role in the life of many animals.”:
Animals use sound not just for communication but also to keep a track of what is happening around them. Under the water an animal’s vision is limited to line of sight, but sounds travel over much vaster distances and so can give an animal a much better three dimensional picture of their surroundings. Indeed, most animals glean a great deal about the world around them from the so-called ‘acoustic scene.’
Given the energy needs and the promise of wind power, Popper is not convinced that offshore wind projects should be delayed. He thinks it is likely that any acoustical effects of construction or operation of turbines could be mitigated. “The real issue,” he tells me, “is whether the construction or operations results in behavioral changes that could cause changes in feeding behavior, reproductive behavior, survival, and so on.”
Vella seems to agree. In a study that he conducted, Vella found that
… when wind farms are operating normally, fish appear to readily habituate and utilize wind farm sites at higher than normal densities, taking advantage of the shelter provided and probably also the additional food resources provided by colonizing animals.
Here he refers to the “artificial reef effect” mentioned before. This could be a good thing – but Vella’s point is that the effects of turbine structures on marine life are simply not well-understood. That’s the point, really – continued research is needed to make sure that the undersea environment is protected as new development takes place. Vella writes,
Offshore wind is a good idea. Certainly, when considering the bigger picture – the reduction of greenhouse gas emissions and subsequent reduction in global warming – it is difficult to find any argument for impeding the progression of this novel technology. However, we must take care not to overlook the smaller picture – the possible impacts on the local environment and the organisms that live there.
Effects on Marine Life “Small in Scale”?
For the most part, the DECC report from the UK, mentioned previously, downplays the potential for environmental problems with wind farm construction. The report’s authors maintain that construction noise is “unlikely to have a significant disturbance effect” on aquatic animals; erosion and seabed damage would be “small in scale and local in extent”; and disturbance of animal species on the seabed would be “negligible in scale relative to natural disturbance and the effects of … fishing.”
DECC acknowledges that the large number of structures required for wind farms could affect marine and bird life. Nevertheless, the report indicates that such structures are unlikely to have real large-scale impact: “The assessment of these effects concludes that based on available evidence, displacement, barrier effects and collisions are all unlikely to be significant to bird populations at a strategic level.”