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Capturing the Wind: Power for the 21st Century
(Released June 2008)

  by Ethan Goffman  


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Advantages and Disadvantages of Wind Energy


The advantages of wind energy are rather obvious, and follow from its renewability. Once a wind installation is up, the power generated is free except for operating costs. And, unlike the burning of fossil fuels, the generation of wind energy gives off no harmful emissions. As the American Wind Energy Association explains, "Wind energy system operations do not generate air or water emissions and do not produce hazardous waste. Nor do they deplete natural resources such as coal, oil, or gas, or cause environmental damage through resource extraction and transportation" (FAQs 14). An enormous percentage of our pollution comes from power plants, notably coal plants. For instance, "in 1997, U.S. power plants emitted 70% of the sulfur dioxide, 34% of carbon dioxide, 33% of nitrogen oxides, 28% of particulate matter and 23% of toxic heavy metals released into our nation's environment" (AWEA FAQs 14).

smokestack spewing pollution
Coal is one of the dirtiest energy sources
Replacing fossil fuel generated energy with wind power reduces such emissions depending, of course, on how dirty the replaced sources are. According to a 2002 study, in the New England area, "one wind turbine rated at 660 kW with a 28% capacity factor (i.e. about 1.5 million kWh/year) eliminates the production of about" 5,300 pounds of SO2, 1,800 pounds of Nox, and 1,100 tons of CO2. (University of Massachusetts). With global warming emissions a huge concern, wind energy's clean nature is more important than ever.

Another advantage of wind power is that converting to it creates jobs. Indeed, "the European Wind Energy Association (EWEA) estimates that every megawatt (MW) of installed wind capacity creates about 60 person-years of employment and 15-19 jobs, directly and indirectly" (AWEA Economic). Conversion to wind power is part of the heralded green jobs explosion. Some portions of a green, sustainable economy are labor intensive; they also require a range of employees, from highly technical to manual labor.

At first a clean, inexpensive, inexhaustible energy such as wind might seem trouble-free. As with most things, though, problems appear on closer examination. The National Research Council sums up possible adverse effects as follows: "use of geologic and water resources; creation or increase of geologic hazards or soil erosion; localized generation of airborne dust; noise generation; alteration or degradation of wildlife habitat or sensitive or unique habitat; interference with resident or migratory fish or wildlife species, including protected species; alteration or degradation of plant communities, including occurrence of invasive vegetation; land-use changes; alteration of visual resources; release of hazardous materials or wastes; increased traffic; increased human-health and safety hazards; and destruction or loss of paleontological or cultural resources" (NRC 20). Many of these problems, however, would occur with any kind of energy facility. Wind power, furthermore, lacks many of the adverse effects of power generation by fossil fuels, but like them, does damage ecosystems through land clearing, roads, and power transmission lines. Problems specific to wind power are chiefly of three kinds: intermittency—wind is variable and undependable; aesthetic issues—people might not like having wind farms near their homes; and environmental issues—notably, wind turbines kill birds and bats.

Intermittency: It comes and goes, then comes again

Wind's intermittent nature leads to probably the chief problem with wind power: its unpredictability. Because it cannot be counted, it must be either supplemented or stored. Wind may therefore work in conjunction with conventional power sources on an electrical grid, relieving them when it is available and saving on the consumption of nonrenewable fuel. It may also be stored for later use.

turbines against the sky
Turbines at sunrise
Most wind turbines are linked to the electrical grid, where wind's intermittent nature can be a problem. The key is to balance wind with other means of generating energy that may be more dependable but less environmentally friendly. Explains one source, "wind farms have the capability of helping stabilize weak grids or areas where loading is variable and heavy. They can be equipped with control mechanisms that allow them to provide reactive power for distribution system maintenance, even when they are not generating active power" (Welander). Energy facilities, then, must "carefully plan how to integrate wind into the mix of power sources" (Schneider). Just what percentage can be safely given to wind is still being worked out. One important test case is Denmark, which balances wind and hydroelectric power in a way that "allows the two renewable-energy sources together to provide cheap and reliable power to the grid at all times" so that "Denmark currently gets about a fifth of its electrical energy from the wind" (Schneider). Similarly, the American Wind Energy Association estimates that wind could theoretically provide 20% of U.S. energy (FAQs 8).

Beyond balancing with other energy sources, wind power can also be stored so that the energy resources captured on a blustery day can be later used during a dead calm. Air compression, water elevation, and batteries are three forms of storage. With compressed-air energy storage, "the basic strategy is to use excess electric power to run compressors that inject air into underground storage fields" (Schneider) where it can be held until needed to feed generators. With pumped hydro, "water generates power as it flows through turbines from a reservoir at high elevation to a lower one. The same water can be pumped back upward using the electricity available at times of lessened demand, allowing the excess energy to be stored" (Schneider). Finally, an Irish wind farm is installing "a vanadium redox flow battery, which in some ways resembles a giant fuel cell, except that it can be charged and discharged repeatedly" (Schneider).

Another potential use of windpower is in the production of hydrogen batteries, a process now performed mostly by electrolysis. Currently, however, such production is so energy inefficient as to be impractical (Heiman).

The Birds and the Bats: The Facts of Life at Wind Facilities

All energy generation has some impact on the environment, at the very least through the resources consumed and habitat cleared in constructing power stations. With wind energy, perhaps the biggest concern is with birds and bats, whose flight paths may take them into collision with wind turbines and towers. Certain species may be prone, through their migratory paths, to collisions with wind farms.

Harm to a single species concentrated in one area could have unforseen impacts. One reason is that "species that are important predators [and] species that are important prey sources can be keystone species in both natural and human-altered ecosystems. . . . Notably many raptors and insectivorous bats fill these roles" (NRC 70). Bats also help to pollinate plants. Destruction of pecies crucial to the ecosystem is thus a concern.

dead raptor
A bird of prey killed at California's Altamont wind farm
The number of bird fatalities due to wind power is relatively small. The US Fish and Wildlife Service estimates that 97-976 million bird collisions with buildings occur annually, at least 130 million with high-tension lines, but only 20,000-37,000 with wind turbines (NRC 71). Only if a very specific bird species is endangered are bird collisions with wind energy facilities any environmental concern. Indeed, "the National Academy of Sciences has published a study that says pesticides and collisions with cars or buildings kill more birds and bats. The Audubon Society has even endorsed wind turbines" (Welander). Currently, "among bird species, nocturnal, migrating passerines are the most common fatalities . . . probably due to their abundance, although numerous raptors fatalities have been reported, and raptors may be most vulnerable" (NRC 7).

The number of bat fatalities appears larger, although data collection is insufficient. Indeed, "the majority of empirical data from wind facilities around the world reside in unpublished reports" so that "knowledge of factors influencing bat fatality is unsatisfactory" (Arnett). Unlike birds, however, bats do seem particularly attracted to wind turbines: "Although bats collide with other tall anthropogenic structures, the frequency and magnitude of fatalities is much lower than those observed at wind turbines" (Arnett). Bats appear to be drawn toward the spinning blades, or confused by them and unable to evade them.

Still, the possibility of wind turbines wiping out a specific species seems remote. A synthesis of available reports shows that "no study reported a species of bat listed as threatened or endangered under the Endangered Species Act killed at a wind facility. However, there were few facilities operating within the range of threatened and endangered species such as the Indiana bat" (Arnett). Migratory bats appeared most at risk, a point which provides a reason for future vigilance.

Fatality patterns provide clues to avoiding further harm to bat communities. A synthesizing review found the "peak of turbine collision fatality in midsummer through fall" (Arnett). Most bats were found to collide "on nights with low wind speed (<6 m/sec). Curtailing operations during low wind periods, particularly in late summer and fall, could reduce bat fatality substantially" (Arnett). Another report also suggests mitigation efforts based on time: "We found that most of the bat activity near wind turbines occurs in the first 2 hours after sunset" (Horn 131). Identifying patterns of bat migrations, and finding out why they are attracted to turbines, thus suggest future mitigation strategies. The more that researchers know, the better: "Future research should concentrate on determining the causes of collisions, potential population effects and development of mitigation strategies to avoid or minimize bat mortality at wind plants" (Johnson). By turning off turbines or otherwise preventing collisions at peak periods of fatalities for endangered species, lasting harm to bat communities and the ecosystems with which they interact can probably be prevented.

Aesthetics and Local Opposition: Can You Stop the Wind?

Quality wind power depends on selecting the areas where the wind is most consistent and strong, but this is not necessarily where there are large numbers of people demanding energy. On the contrary, "the highest-quality largest-scale wind resources usually are far from the main centers of demand, i.e., where people live and work" (NRC 33). Building far away means additional costs and environmental impacts due to transportation, transmission lines, etc.

protestors & signs
Protest against wind turbines in South Gippsland, Australia
On the other hand, building close to people has aesthetic impacts that can raise local opposition. Although some find wind facilities attractive and dynamic, to others they are strange and unwieldy and detract from an area's local character. Frequently, they do not fit in with planning and zoning; "the turbines often are taller than any local zoning ordinance ever envisioned, and they are impossible to screen from view" (NRC 143). At times they may disrupt an area's historic or even religious significance. Moreover, turbine noise can reach troublesome levels within a half mile radius, although generally no further (NRC 153). In addition, their flickering shadows can cause unsettling feelings, at least in northern Europe because of the obliqueness of the sun's angle, although this is not a problem in the continental United States (NRC 160).

All of these problems can generate local opposition to a given wind project, through what is sometimes called the "Not in My Back Yard," or NIMBY, factor. For instance, North Carolina residents objected to a wind power project, raising "questions about the prospect of living near wind turbines that would dwarf the Cape Lookout lighthouse and stand taller than the Wachovia building in downtown Raleigh" (Rawlins). More famous is the Cape Cod project "to install 130 windmills taller than the Statue of Liberty across a shallow 24-square-mile area about 6 miles off Cape Cod" (Ebbert). Local opposition dramatized their objections through "a troupe of actors who wore fisherman's gear, a chef's hat, and a bird costume to represent, respectively, the commercial, tourism, and avian interests they say would be hurt by the wind farm. The bird, wearing Band-Aids, begged fervently to be saved" (Ebbert). The project was also opposed by environmental icon Robert F. Kennedy, who regularly vacations in Cape Cod, and led to division within the environmental movement.

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