CHAPTER 2
Second Wind: Challenges and Impacts of Small Wind Energy

Most people never run far enough on their first wind to find out they’ve got a second.

–WILLIAM JAMES

Not to deflate the helium out of your Magenn wind turbine balloon (see Chapter 12 on new and future technology), but no energy source is perfect, even if some enthusiasts can’t see beyond their own nacelles.

Even if you are a small wind advocate, you may want to read about these common myths and shortfalls. For one thing, opponents to your wind turbine might appear at your zone appeal or during construction, with a hair-raising study about wind turbines that you might not be prepared to process.

Without advocates like you to clear the air, local ordinances could require an endless list of study reports and certifications, similar to what is required for utility turbines. To give you an idea, here is what is currently required for utility-sized turbines, although thankfully not for small turbines … yet:

• Soil survey of the entire area

• Tower engineering

• Tower foundation engineering

• Structural certification for the tower

• Bird, bat, and noise studies

• Ice “throw” engineering and calculations

• Blade throw calculations

• Telecommunication interference testing

• Environmental impact

• Study average wind speed monitoring power

• Output reporting and economic viability analysis

• Agricultural impact statement

• Architectural projections of what the turbine will look like on the property

• Documentation of nearby sensitive environmental areas

• Wind access agreements with neighbors

• An abandonment plan

• Determination of the area affected by shadow flicker

• Stray voltage testing

• HAZMAT (hazardous material) reports

• Well testing

• Electrical wiring insulation testing

• Site reclamation plan

• Bonding

Obviously, every neighborhood is not so restrictive. There are many areas in the world where wind turbines are as welcome as a hot apple pie at the windowsill. However, some of these requirements came about due to previous experiences with older wind or related technology. Most of the reported negatives of wind energy relate primarily to industrial-scale turbines, and historically, many experts and researchers have essentially ignored small wind (Figure 2-1), assuming that it lacks a significant size or quantity to even warrant research. Still, some work has been done, and many questions continue to be raised, sometimes by zoning boards and others with decision-making powers. At the very least, we think it’s important to give some of these issues a thought when you envision your dream system so it can be as truly sustainable as it can be and meet all your expectations.

FIGURE 2-1 How’s that for a breath of fresh air? Whisper 0.9 kW small wind turbine in Spanish Fork, Utah. Windward Engineering/DOE/NREL.

We cover these challenges in detail, but also include a concise chart that you can rip out of your own personal book (not from the library book!), or better yet scan and bring wherever you go. If that isn’t good enough, we provide some footnotes and web links. Remember, information is power.

Energy Storage and Transmission

I want it, and I want it now!

If you want reliable electricity, wind will always be here, and you can count on it long after you pass. That makes it a reliable energy resource. Yet, wind does not blow 24/7/365 in most locations. If it did, we would certainly like to see the people who live there and their culture. They would probably be applying ChapStick to their faces and using some clever transport utilizing the prevailing winds, not unlike sailing ships. And they might all commute to work in a similar direction. For the rest of us, wind currents are typically strongest in the late fall, winter, and early spring, but generally calmer during the summer, unless you are in a monsoon or hurricane zone. And even during the day, wind speeds vary based on your location and terrain.

So, this reliable, renewable energy has an Achilles heel. Unlike Odysseus, you can’t just open up a woven bag to release the wind force. One of the biggest advantages of coal-burning power facilities is dispatchability. Dispatchability, or maneuverability, is the ability of a given power source to increase and/or decrease output quickly on demand. Maneuverability is one of several ways grid operators match output (supply) to system demand. Need more energy? Insert more coal. Need less energy? Burn less coal. Unlike conventional fuels, we cannot slow down or speed up the wind. And shutting down a wind turbine is not the answer. Disengaging the rotor from existing wind force is technically not the same as controlling dispatch—it is more like letting the fuel line leak.

The increasing role of the wind’s variable renewable sources has prompted concerns about grid reliability and raised the question of how much wind can be placed into the grid before vast energy storage is needed. The question becomes an economic issue. Currently, the grid can accommodate a substantial increase without energy storage, so long as we share the resources and loads over larger areas, perhaps over continents. Beyond this level, the impacts and costs are less clear, but currently, storing electricity is more expensive than dispatching when needed.

For the most part, practical options of storing energy at a time when demand is low are still in the exploratory phase. They consist of a number of strategies, including batteries, pumping water, conversion to heat, and other ideas.

Batteries are certainly one possibility (Figure 2-2), but they require maintenance, and they are currently way too expensive to use on the scale of the grid. Some analysts have predicted that electric and plug-in hybrid cars may soon be able to leverage their on-board batteries for energy storage. The idea, often called vehicle-to-grid (V2G), is that much of the excess energy that is generated by wind turbines at night, when the winds are blowing but people are asleep and not using energy, would be “stored” in the batteries of cars that are undergoing charging. Then, during the day, for those people who aren’t using their cars—because they’re at work, say, or home sick—they could sell back power to the grid at a time when demand is high, the wind isn’t blowing as hard, and electric rates are higher. The concept of wind-powered cars also means that clean power would be directly offsetting use of foreign oil, which is something that has broad political appeal.

FIGURE 2-2 Batteries can be used to store renewable energy, but they are expensive, require maintenance, and are not completely efficient. These batteries in Mexico got corroded since they sit in an equipment room that hits 122 degrees Fahrenheit. Charles Newcomber/DOE/NREL.

The catch is that we are, at best, several years away from V2G, in part because our grid isn’t yet “smart” enough to have that fine a level of two-way control. Only a relative handful of smart meters have thus far been installed, and they aren’t cheap. Further, there are very few electric and plug-in hybrid cars on the road, although that is expected to change over the next few years.

Finally, current battery technology isn’t quite up to the task. At a recent media event, Andrew Tang, who heads up smart grid development for the utility Pacific Gas & Electric, said that he doesn’t think it will be worth it for consumers to “rent out” their batteries for some time. That’s because each time power is put in and then taken out of a battery, that cycle decreases its lifespan, and that’s a significant concern when car battery packs cost several thousand dollars. According to Tang, the pennies that a V2G participant would be credited from a utility wouldn’t cover the wear and tear on their battery—at least until batteries improve and electricity rates go up.

Another grid energy storage method that is being researched is to use off-peak or renewable-generated electricity to compress air, which could then be stored in an old mine or some other kind of geological feature. Then, when electricity demand is high, the compressed air can be heated and expanded to generate electricity. Similarly, some power plants use their excess energy at night to pump water uphill. Then, when they need extra juice during the day, they release the water, and convert the energy into electricity via water turbines, just like in the Hoover Dam.

In a more complicated process, utilities could make hydrogen at night with their excess energy, then run that through a fuel cell during the day to provide extra power, or use it to run fuel-cell cars (Figure 2-3). It would be a clean process, especially if the initial energy were generated by the wind. Fuel cells are currently too expensive to work on such a scale, but may be coming.

FIGURE 2-3 This Honda prototype car runs on hydrogen, thanks to an onboard fuel cell. If the hydrogen is produced by electricity generated by a wind turbine, that makes for a completely clean loop. Brian Clark Howard.

Another option is to convert the surplus electricity to public or residential heating services. The Bonneville Power Administration (BPA) has recruited homeowners in Washington to install special devices on their water heaters that communicate with the electrical grid. They tell the heaters to turn on or off, based on grid conditions and the amount of renewable energy that’s available.

The benefit of your grid-tied small wind turbine is that energy storage is much less of a problem, because small generators are distributed, meaning they produce power right where it is being used. However, if your system is off the grid, then you currently have few options to store wind energy for later use: namely, batteries, and trust us, you aren’t likely to be able to afford, or want, that many of them. In a few years, you may be able to invest in a home fuel cell. (They’re selling pretty well in Japan now, thanks to big government subsidies.) Ideally, you will be able to find some uses for any extra power you generate, such as running an electric saw, power washer, or floor cleaner. So, we guess you should have your wind dictate when you should get off the couch.

If your system is tied into it, then the grid can effectively act as your storage bank. In most places, where there is some type of net metering agreement, you’ll get credited for energy you put into the grid, and that’s likely the best deal you’ll find. Even if there is a massive ramping up in the number of wind turbines, the grid should be well equipped to handle it, since it will be so distributed.

Finally, one more potential problem with new utility wind farms is that they often require new expensive transmission lines to pump the power they produce into the grid. Installing high-voltage lines is a major undertaking that disrupts the environment and makes for angry neighbors. However, with small wind, everything is at a much smaller scale.

Environmental Impacts

Everything we do has some kind of impact on the environment, and wind power is no exception. For the most part, wind turbines are very eco-friendly, when you consider their whole lifecycle and how much clean power they can produce. Still, there are a few things to be aware of.

Noise

Just like all moving things, wind turbines make some noise (Figure 2-4). It’s definitely an important issue to consider, and you may notice that turbine manufacturers tend to heavily tout the alleged quietness of their respective machines. Brian Levine, cofounder and vice president for business development of Michigan-based manufacturer WindTronics, told us that, according to his experience, noise tops the list of consumer concerns (followed by effects on animals, vibration, and tower height). Levine’s core product, a Honeywell-licensed small turbine, is said to be exceptionally quiet, although some wind experts say the technology is still unproven.

FIGURE 2-4 Wind turbines have moving parts, so they make some noise, but they are usually comparable to many other mechanical devices we are regularly in contact with. GE Reports/Designed by Group SJR.

So, the question is, are small wind turbines loud enough to be considered annoying, and might they have physiological effects? There have been some reports of complaints about noise from small wind turbines, ranging from perceived annoyance to alleged illness.

However, an expert panel in 2009 prepared by AWEA and CanWEA concluded the following:

• There is no evidence that the audible or subaudible sounds emitted by wind turbines have any direct health effects.

• The ground-borne vibrations from wind turbines are too weak to be detected by, or to affect, humans.

• The sounds emitted by wind turbines are not unique.¹

“Wonder why I can’t hear my turbine while watching football on TV?”

Let’s take a closer look. Sound volume is measured in decibels, dB(A), with a range from 0 dB(A) (imperceivable) to over 150 db(A) (damaging over the long term). The human ear can distinguish sound differences of about 3 dB(A), or greater than ambient noise. But don’t be fooled: 3 dB(A) is not 3 percent, it is a 50 percent increase in the sound level. Nearby trees on a breezy day will measure about 55 to 60 dB(A) on a decibel meter. The average ambient noise in a house is about 50 dB(A). A conversation is about 40 to 50 db(A).

The good news is that most of today’s residential wind turbines produce the same level of sound as a conversation or background noise—40 to 50 decibels—over most of their operating range.

The second component of sound to consider is frequency. That’s because even though the volume of sound coming from a wind generator may be the same as the ambient noise, the frequency, measured in Hertz (Hz), may be different. Dogs, traffic, radio, and kids could be at the same decibel level, yet at a different sound frequency. Therefore, wind turbine sounds may be distinguishable from ambient noise even though they are not louder. Does this necessarily mean they are annoying? That’s a subjective question, and something everyone has to experience.

Now, not many people live at the base of the tower, so distance plays an important role as well. As you double your distance from the origin point of sound, you reduce the intensity by a factor of four—the inverted square ratio (or I/d²). Therefore, any audible sound emitted from a wind turbine will quickly blend into the background noise with increasing distance from the tower.

Sound from a wind generator normally originates from two sources: the drive-train and the blades. In machines that have a drivetrain—mostly utility-scale turbines—there is a gearbox transmission, high-speed generator, and mechanical brakes, all of which can make noise. However, most newer small wind generators are direct drive, meaning the rotor is directly connected to the alternator/generator, without a transmission, similar to computer disc drives. Because they are direct drive, the generators used in these systems are slower speed, and they do not usually produce mechanical or tonal noise.

Most of the sound that comes from a wind turbine is aerodynamic noise caused by the air resistance, or lift drag, as the fiberglass or carbon fiber blades pass through the air. As wind speed increases, so does the speed of the blades, and they get louder.

Aerodynamic noise is also a function of the speed of the blades as measured from the blade tips. If you are selecting your turbine, the data sheet should mention its tip speed ratio (TSR). This is a term that refers to the speed of the tip of a wind generator blade in relation to wind speed. For example, a wind system that operates with a TSR of 10 means that when the wind speed is 12 miles per hour (mph), the tips of the blades are moving at 10 × 12, or 120 mph. Increasing tip speed results in more noise. A well-designed, three-bladed rotor with a TSR of about five to seven (125 to 175 mph) will emit sound that is barely discernible from ambient noise with a decibel meter.

Large commercial wind turbines can have an additional aerodynamic noise that is often referred to as “blade thump.” Some observers say this sound is usually only audible within 300 feet of the turbine, but blade thump has been reported at distances of up to 1.5 km away. This sound is caused by the large blades passing the tower of the turbine. Although measurements indicate the noise is not particularly loud, recent surveys from people who live near wind farms claim it can be irritating over time because of its heartbeat-like, rhythmic nature.²

For small turbines, depending on the design type, there are three scenarios in which sound can increase above normal operating conditions:

• Loss of grid connection

• When the batteries are full

• Exceedingly high wind speeds

When a utility blackout occurs with a grid-tied wind system (without backup), the wind system loses its load, the grid. Some turbine systems are still designed to “freewheel” during such an event; that is, the rotor is temporarily disengaged from the generator, permitting the rotor to spin freely in the wind. At this point, it can become noticeably louder. The system resets to normal as soon as the grid is reconnected. If you are home, the solution is easy: if you don’t want the neighbors to complain about a whining machine, like bringing your barking dog in the house, simply shut the wind generator off with a manual braking mechanism that is included with these types of purchased models until the grid is back on.

Note that freewheeling will damage or even destroy many turbines, and wind experts like Ian Woofenden often train people to design their systems to avoid it, so in all likelihood this potential source of noise won’t apply to you. Some models, like Southwest Windpower’s Skystream 3.7, have protection systems that engage a dynamic magnetic brake if power is interrupted. Strong winds could not budge those blades.

The second scenario involves off-grid wind systems when the batteries are full and cannot accept more energy, resulting in an overvoltage in the line. This most often occurs during prolonged periods of sustained high winds. Some systems have a safety feature designed to freewheel when this event occurs. Or, as is more commonly recommended, the excess energy can be diverted, or “shunted,” to a dump load, converting the electrical energy to heat. This effectively keeps sound within normal operating parameters.

The last scenario is achieved when the wind speed exceeds the turbine’s cutoff speed. At this time, the turbine has already furled as far as it can go and the rotor will freewheel, creating aerodynamic noise not only from common drag, but also from the air turbulence as a result of the wind hitting the blades at an angle of more resistance.

According to Karen Sinclair, a senior project leader with the National Renewable Energy Laboratory (NREL)’s National Wind Technology Center in Colorado, consumers should shop for turbines that have been tested to international standards, which she says include noise standards. (American standards for small wind have recently been developed, but as of this writing few turbines have yet finished qualifications.) “But even with standards, if turbines are not properly sited they can be annoyingly loud,” Sinclair told us via phone. Similarly, some home-brew turbines can be quite noisy.

Small-scale wind turbine manufacturers are improving their technology and making it quieter. For example, sound insulators are now commonly installed on the tower stub to minimize sound conductance from the turbine. Dynamic braking, which controls the rotor in high speeds, effectively increases resistance via electromagnetic force applied onto the spinning rotor, slowing it down. Consequently, it also increases its efficiency.

Boosters of vertical axis wind turbines (VAWTs) often argue that their products are quieter than horizontal axis wind turbines (HAWTs). In fact, it’s one of the reasons why VAWT manufacturers sometimes promote them for urban areas, although that’s also controversial.

Colin Malaker, a dentist in Columbia, Missouri, recently installed a small WePOWER VAWT in front of his practice, which he says delights his patients (Figure 2-5). “It’s very quiet, I never hear it,” Malaker told us. “When it’s spinning really fast it maybe sounds like a B-52 at 30,000 feet. But a microwave oven is twice as loud,” he added. In addition to dentistry, Malaker runs a small renewable energy business on the side, and he plans to sell WePOWER products.

FIGURE 2-5 Colin Malaker, a dentist in Columbia, Missouri, recently installed a small WePOWER VAWT in front of his practice. He says the turbine is very quiet. Colin Malaker.

We’ll get into the differences between horizontal and vertical wind turbines later, but it’s worth noting that noise is often brought up in the discussion.

Power Up! We recommend that you try before you buy, especially since perception of sound can be fairly subjective. It’s a good idea to visit several installed examples of the turbine you are considering. Go during different wind and weather patterns, and walk around it. Measure out the distances on your site from your residence to the tower and to any other important features. Make sure you have detailed conversations with your family and neighbors before you pour the concrete and start moving electrons. Otherwise, you could end up with an angry family and angry neighbors.

Infrasound and Low-Frequency Sound

Infrasound is a sound that is lower in frequency (<20 Hertz) than human hearing can perceive. Think the opposite of a high-pitched dog whistle.

Infrasound is generated internally in the body (by respiration, heartbeat, coughing, etc.) and by external sources, such as wind and breaking waves, work environments, industrial processes, birds, vehicles, and air conditioners. In short, it is ubiquitous. Turbines are also capable of generating infrasound, but usually at levels that are similar to what’s already prevalent in the environment.

Studies suggest that the levels of infrasound near modern commercial-scale wind turbines are in general not perceptible to humans, either through our ears or any part of our body. Putting it in perspective, the levels as measured from dwellings in proximity are no different from what’s measured from natural gas compressor stations, industrial sewage pumping stations, and other power plants. In addition, there is no evidence of adverse health effects due to infrasound from wind turbines.

No obvious health effects are found among those who are exposed to infrasound below 100 dB(A). However, those who are chronically exposed to infrasound above 110 to 120 dB(A) “present notable subjective sensation of autonomic neurobehavioral dysfunction (somatization, depression, hostility, phobic anxiety, and psychotism)”.³ Thankfully, all modern wind turbines are typically designed to well below half of this level as measured to any occupied building.

Dr. Nina Pierpont, a population biologist, recently completed a self-published report speculating that a constellation of physiological symptoms, which she christened “wind turbine syndrome,” are caused by low-frequency noise and vibration, as well as shadow flicker, from large wind turbines, affecting the body’s various balance organs of the inner ear. Low-frequency sounds are caused by eddies of turbulent air that form off the blades, and they travel much farther than infrasound and high-frequency sounds.⁴ Pierpont’s small case study obtained reviews and notices from several practitioners in related fields, but there are as yet no reports in the peer-reviewed clinical literature linking wind turbines to these or any other symptoms. British sleep expert Christopher Hanning, however, has noted that sleep deprivation can cause most of the reported symptoms.⁵

All that being said, it is important to remember that these effects are greatly diminished when it comes to small-scale wind. In conclusion, there is scant evidence of harm from infrasound produced by wind turbines, although it is worthwhile to keep abreast of current research and common perceptions. In order to give the benefit of the doubt, turbines can be sited a sufficient distance from human habitation. It may also be possible to further modify the blades to reduce turbulence.

Perception and Annoyance

Wind turbines are among the more recent technologies encroaching onto our landscapes. The public has already adjusted to power lines, water towers, and cell towers. Those things are so common that we usually don’t take notice. But even some of the best advocates of wind power and renewable energy are not always enthusiastic about seeing wind turbines close to home. (Just ask the local environmentalists who have spent years opposing plans for a wind farm out in Nantucket Sound.)

Unfortunately, if someone already didn’t like turbines, having to see one or more from their residence tends to make the person like the technology even less.⁶ In addition, in several surveys of homes near large wind farms, turbine noise was said to be more annoying than transportation or industrial noise at comparable levels, possibly due to the intermittent nature of the sound. The exception is people who benefit economically from wind turbines, who tend to have a higher threshold for annoyance, despite exposure to similar sound levels.⁷

Perception and annoyance are also linked to terrain and urbanization:

1. There is some evidence that people are more annoyed with turbines in rural areas versus suburban areas.

2. In a rural setting, hilly terrain may increase annoyance versus flat terrain.⁸

Therefore, it may pay to take the unique local environment into account when planning a new wind turbine.⁹ However, it’s also important to remember that any annoyance issues are greatly reduced when it comes to small wind turbines, and that most studies on the issue have only looked at large systems.

Flicker Effect

Shadow flicker effect can occur when a wind turbine’s rotor casts a moving shadow on an observer. The phenomenon only occurs when, to the viewer, the sun appears to set or rise behind the spinning blades of a turbine. The effect creates a pulsating light that can last for 15 to 30 minutes.

Many factors must be present for a shadow flicker effect. It occurs only in specific directions, depending on the latitude (west-northwest and east-northeast in the Northern Hemisphere, east-southwest and west-southwest in the Southern Hemisphere), and needs penetrating sun at certain specific times of the day. In addition, the size of the turbine blades has to be substantial (Figure 2-6), meaning that micro-and residential-size systems are not large enough to cause the effect.

FIGURE 2-6 Most of the issues people bring up with regard to wind turbines relate only to utility-scale installations, such as flicker effect and low-frequency noise. Brian Clark Howard.

Shadow flicker from commercial-scale turbines has occasionally been blamed for health effects, ranging from distraction while operating equipment to vertigo, headache, and nausea. Scientists are currently researching whether any shadow flicker from wind turbines might cause a response, such as seizures, in the approximately 0.025 percent of the population that suffers from photosensitive epilepsy.¹⁰

A few studies found there is a negligible risk that three-blade, commercial-size turbines in specific conditions will have the blade interrupt sunlight to your eyes more than three times per second (60 revolutions per minute). This factor is known as the flash frequency. For this effect to occur, the viewer would need to be located in alignment with persistent sunlight and the turbine rotor, with the sun appearing at a position relatively low in the sky.

However, until such results are irrefutable, researchers at the Neurosciences Institute in Birmingham, United Kingdom recommend that, regardless of the viewing distance, shadows cast by turbines “should not be viewable by public”¹¹ if the flash rate exceeds three per second (60 revolutions per minute) and when the sun appears low in the sky (usually sunrise and sunset).

Fortunately, morning events rarely coincide with waking hours and usually pass unnoticed, but evening events can cause nuisance, similar to the sun’s glare in the car window. Large wind farm planners can take steps to reduce the flicker effect by proper siting in relation to occupied or traveled areas or with tree plantings in the area of the shadow.

The Danish Wind Industry Association has graciously offered a shadow calculator to use for your assessment guidedtour.windpower.org/en/tour/env/shadow/shadowc.htm.

Resource

Online Shadow Calculator

bit.ly/shadowcalculator

Visual Influence

Perhaps the most commonly voiced opposition to wind turbines is along viewshed lines.

Technically, a viewshed is an area of land, water, or other environmental element that is visible to the human eye from a fixed vantage point.¹² In other words, a viewshed is what people see. Of course, what people like to look at is highly subjective and individualized, although many people can agree that natural is good, especially as the world becomes more urbanized.

Many people report that they find wind turbines aesthetically appealing, even awe inspiring or beautiful. To these folks, wind turbines fit right into the landscape. Others, however, just plain don’t want to look at them sticking up in the air—spinning continuously and “making noise.” Other factors also affect the visual appearance of a wind generator. Larger turbines rotate more slowly than smaller ones, and a wind farm of fewer larger turbines is often preferable to an installation of many smaller ones. In some cases, arranging the machines in a straight line makes them more favorable to the public.¹³

Occasionally, neighbors ask if a turbine could be painted a certain color, say blue, to “blend into the sky,” or green, to “blend into the hills” (Figure 2-7). Whether you seriously consider such a request is up to you, though note that there’s little evidence to suggest that any particular color ultimately helps a turbine blend in. Some people have made up turbines to look like spinning flowers, and Kevin had the idea to paint a nacelle to appear like a propeller airplane. Obviously, blade size ratio to the plane would be exaggerated, but what a creative solution for alternative energy at an airport or aviation museum!

FIGURE 2-7 After Rosalie Bay Resort installed a wind turbine in Dominica in 2008, one neighbor asked if it could be painted blue or green. However, there’s little evidence this will make a difference. Rosalie Bay Resort.

Opinions definitely change, although it can take diligence, time, and patience. Commonly, public support of wind turbines tends to rise once the machines are installed and operating, according to several surveys carried out in the United Kingdom and Spain.¹⁴ Like other improvements—high tension wires, water towers, cell towers, oil refineries—all utility landmarks eventually become ubiquitous within the community. If someone gave you local directions in your own town and used the city’s water tower as a landmark, you might say, “Where is that?” The opposite can also be true for wind. It could be a landmark that represents the community’s stand on some ideal lifestyle. In fact, in 2008, the city of Rock Port, Missouri, proudly announced that it was America’s first town to be wholly powered by wind energy.

Sometimes, attempts to oppose wind turbines may have their roots in a feeling that the community has had no control over previous developments. Being that wind turbines don’t yet have the same acceptance rate as other tall structures like electric, cell, and water towers, some people feel they have more opportunity to oppose them at zoning hearings. Did you know that when windmills were first introduced in Holland, many people considered them undesirable?¹⁵ People have long been resistant to change. But then things change.

Property Value

As the pace of wind project development increases, opponents raise claims in the media and at siting hearings that property values will be hurt. As we have pointed out, wind turbines do generate some noise, can produce flicker effect, and are visible with moving parts (Figure 2-8). But again, such issues are greatly reduced, or even eliminated, when it comes to small turbines. So do wind turbines affect property values, positively or negatively? This is a serious question that deserves to be empirically examined.

The Department of Energy sponsored a study in 2009 that involved collecting data on almost 7,500 sales of single-family homes situated within 10 miles of 24 existing wind facilities in nine states. The conclusions of the study are drawn from eight different pricing models, as well as both repeat sales and sales volume models. The research concluded that

FIGURE 2-8 Are wind turbines beautiful or eyesores? It’s a highly subjective question, but one worth asking in your community. Brian Clark Howard.

“Neither the view of the wind facilities nor the distance of the home to those facilities is found to have any consistent, measurable, and statistically significant effect on home sales prices.”

This conclusion does not dismiss the possibility that individual homes or small numbers of homes have been or could be negatively impacted. The results suggest that if these impacts do exist, they are either too small and/or too infrequent to result in any widespread, statistically observable impact.¹⁶

Another study done by the Renewable Energy Policy Project (REPP) found no evidence that property values decreased as a result of large wind farms. Quite the contrary:

“For the great majority of projects the property values actually rose more quickly in the viewshed than they did in the comparable community. Moreover, values increased faster in the viewshed after the projects came online than they did before.”¹⁷

In Europe, several countries have conducted similar studies and came to similar conclusions.^{18, 19}

However, there still can be a difference between actual property values and the perception of what will happen to property values. According to an economic analysis of a proposed (and controversial) wind farm in Nantucket Sound in Massachusetts, a survey of tourists, residents, and real estate agents suggests

“Homeowners expect the project to decrease their home values by an average of 4 percent.”²⁰

That proposed wind farm hasn’t been built yet, as of this writing, so the actual effect cannot be reported, although historical trends suggest that the homeowners will be pleasantly surprised that their fears were unjustified.

Noise has also been the bigger factor in determining property value. In the United States, lawsuits and complaints have been filed in several states, citing lost property values in homes and businesses located close to industrial wind turbines due to noise and vibrations. As of this writing, these cases are unresolved.²¹ In one case in DeKalb County, Illinois, at least 38 families have sued to have 100 turbines removed from a wind farm there. A judge rejected a motion to dismiss the case in June 2010.

Opponents and proponents have surmised that negative environmental effects may be abated by better placement, new sound reduction technology, corporate buy-outs, and better municipal policies.

Interestingly, Denmark adopted a policy in 2009 that requires developers to pay compensation for alleged loss of property value following erection of a wind turbine more than 25 meters (82 feet) high. The value must be determined by an appraisal authority.²²

Still, there is some evidence that wind turbines placed in strategic locations may actually improve property values of the community. It can represent to a new homebuyer savings in energy costs, and holds the image of reducing their carbon footprint. In fact, a number of residential developments have been announced across the country that will feature small wind turbines, with that feature prominently promoted in advertising materials. As Rick Rosa of the Solarium apartment building in Queens told us, a wind turbine can help a property get noticed.

Indeed, many wind turbines are themselves tourist attractions. In a popular vacation area of Scotland, a poll found that 80 percent of tourists said they would be interested in visiting a wind farm if it were open to the public. An impressive 91 percent of respondents said they would not be put off from visiting an area because of the presence of wind farms. In Denmark, many tour agencies run boat trips to take visitors to see the offshore wind farm at Middelgrunden, near Copenhagen. In the United States, a National Renewable Energy Tour visits homes that showcase clean technology. In Swaffham, Norfolk, over 50,000 tourists have climbed the wind turbine tower to see the spectacular sights from the viewing platform, 65 meters above the ground.²³ If you are seeking more than increasing your property value but are into some passive income, wind turbines evidently have a particular market appeal, and certainly are more visible than the towering large panel signs.

In summary, it’s undeniable that a small wind turbine could affect your property value or that of the neighbors around you. This is highly dependent on many factors, although the evidence we do have, particularly from studies of large wind farms, suggests that fears are overblown. With proper design, placement, and diligence in educating others within the community, you are promoting a positive image that few can refute, and buyers might find of value. If recent studies and historical trends are any indication, chances are good that your turbine will not harm property values, and may actually contribute to them.

INTERCONNECT

Kevin’s Unique Dome Home

When we talk about property value and visual appeal, I must insert my own unique structure. In 2004, I directed the construction of my “green” dome home (Figure 2-9). It didn’t receive positive feedback from the neighbors. I got yelling and suggestions of where I could place my dome.

FIGURE 2-9 When Kevin started building his dome home in 2004, some of his neighbors were initially upset. But he found that they were more accepting of his small wind turbine. Kevin Shea.

When I planned to build my wind turbine, I was well aware of what I would expect. But I got the opposite reaction. I have found eager guests in my driveway, asking about the wind turbine and how they can get one. When passersby see the 70-foot-wide dome, they might think it is a salt or grain storage facility (I do live next door to a farm), but put up a wind turbine and they were attracted like bees to a flower.

I would like to absolve myself of any responsibility for any vehicle accidents that were caused by drivers who inappropriately stopped in the middle of the busy road to view the turbine. You know who you are. In addition, I don’t know how these accidents affect the property value.

Electromagnetic Transmissions

Some people ask if wind turbines might interfere with radio, television, or cell phone signals. Your neighbor might want to know if your proposed turbine is going to cut off that critical Superbowl play or the finale of Lost, or that emergency phone call or Pandora Internet radio streaming from their Wi-Fi.

Some studies have looked at such issues as:

• Electromagnetic interference (EMI), which happens when a wind turbine creates and radiates a frequency in the radio band that is being used

• Near-field effects, which is the change of the characteristics of an antenna when in close proximity to another object

• Diffraction, which is a signal loss when a radio wave is partially blocked

• Scattering (reflection), which is when the radio waves are reflected from a metallic surface²⁴

All of these issues sound serious. Fortunately, small wind turbines have never been found to create interference with signals.²⁵ Importantly, the materials used to make the blades are typically nonmetallic (composites, plastic, wood) that don’t cause reception problems. Small turbines are too small to “chop up” any signal. In fact, small wind systems are commonly used today to power remote telecommunication stations for both military and commercial uses. Many years ago, a few wind turbines equipped with long, metallic blades did cause some localized problems, but they are no longer commonly used.

Today, it is only large wind turbines, which may use metal in their blades, that can interfere with radio or TV signals, but only if a turbine is in the “line of sight” between a receiver and the signal source, and that’s something installers can plan against.²⁶

Radar

Radar is basically designed to filter out stationary objects and display moving ones, so moving wind turbine blades can create radar echoes. Only the newer large wind turbines have been noted to affect the 50-year-old defense radar technology, due to their enormous coverage. They tend to create a “mirage” on radars. Peter Drake, technical director at Raytheon, a major provider of radar systems, has said, “A wind turbine can look like a 747 on final approach.”²⁷

After elements in the British and U.S. military expressed concern, some wind projects were halted until a study was conducted. Research by the British government concluded that some radar installations may require no change, while others can be modified to ensure that air safety is maintained in the presence of wind farms.²⁸ It’s a purely technological issue—potential fixes include new coatings for wind turbine blades, software patches for existing radar systems, and overhauling obsolescent radar systems.²⁹

If your wind project is proposed near an airport or military airfield, this issue might attract some wind turbine opponents. However, rest assured that interference is generally limited to small, low-flying airplanes that are physically shadowed by your turbine. So, even if the radar technology is outdated, there is low risk that a small-scale turbine would have any effect on radar.

Ice Throwing

Some people have a vision of wind turbines in winter as spinning pinwheels of death, flinging dagger-sized icicles off their blades at 100 miles per hour (Figure 2-10). However, in reality, wind turbines shut down during icing events, due to either imbalance detection or the control anemometer icing (the control anemometer tells the turbine how fast the wind is blowing). Any ice buildup tends to shed in thin pieces while the turbine is at rest or while it is starting up. Not too much different from the eaves of a roof.

FIGURE 2-10 Although many people are afraid wind turbines will fling shards of ice, we aren’t aware of any damage. Pictured is the 1.5 MW wind turbine at Jiminy Peak in Massachusetts, which provides about a third of the ski resort’s power needs. Brian Clark Howard.

Current turbine setbacks from roads and residences should be sufficient to protect the public from ice shed. To date, we are not aware of any insurance claim for injury due to ice shed from turbines.³⁰

Ecological Impacts of Small Wind Turbines

Small wind advocates sometimes brush off the potential environmental impacts of their machines, arguing that their devices are too small to make much of an impact on nature. However, we feel that it’s worthwhile to give a thought to the entire lifecycle of the project, from the energy it takes to produce and transport the equipment to preparation of the site and operation and maintenance. Not only will you be participating in a process that’s as “green” as possible, but you’ll also do credit to the industry, which has its fair share of critics. And we can follow that with a more socially and politically popular topic—we shall teach you about the birds and bats!

Embodied Energy

As with anything manmade, there is going to be some environmental impact involved with the hardware itself. According to Ian Woofenden, freestanding manufactured towers require more energy to produce than other tower types, largely because they require more steel and concrete, the latter of which is particularly energy-intensive.

“You could also make a case for the cheapest tower for the job being the most eco-friendly, because it will probably require the [fewest] resources,” Woofenden told us. “That would probably be tilt-up for the tower, since they need less concrete,” he said.

Wind turbines will take some time to “pay off” the amount of emissions that went into setting them up, so it’s good to get something in place that has a shot of actually producing energy. The more clean power you make, the greener your machine. Similarly, aim for longer-lasting equipment, as that means fewer resources are needed.

The better tuned you keep your machine, the fewer problems you’ll have down the line. Where possible, choose locally produced equipment, as that decreases transportation costs and impacts. Hire help locally, too, as that cuts down on mileage and builds local expertise. When a part is no longer useful, recycle it at your nearest scrap yard.

Site Preparation

Setting up a wind turbine can cause disturbance to soil and vegetation, particularly if large earth-moving equipment or cranes are needed (Figure 2-11). Still, since the scale is relatively small, the impact should be pretty minor and relatively temporary.

FIGURE 2-11 Preparing the site for a turbine tower can be fairly invasive, and can require large earth-moving equipment. Take care to minimize erosion and long-term impact to the ecosystem. Paul Anderson/Wikimedia Commons.

Even so, you can do your part to try to minimize impact by making sure you don’t cause problems with erosion or soil compaction. Occasionally, when turbines have been set up in very sensitive, or very remote, areas, they are installed via helicopter. That reduces impact of overland trucking, but it can be expensive.

Potential Impacts on Birds

Kevin would like to preface this section by mentioning that he is building a wildlife reserve, which will hopefully support an abundant bird and bat population. In our opinion, mitigating bird mortality is a serious matter.

In fact, for every person who asks if wind turbines “throw” ice, we’ll introduce you to four who insist the spinning blades chop up birds like the Iron Chef whacking at an onion. Part of the reason for that perpetuated perception is that, yes, some early wind farms did have a noticeable impact on birds, namely the famous installation in Altamont Pass. However, a number of specific factors were at play, most of all turbine placement in proximity to existing bird migration, mating, and nesting areas. We shall say this for energy production as well as avian life preservation: location, location, location. The utility-scale industry has learned a lot about mitigating effects on birds by conducting extensive analyses, raising the heights of towers, and slowing down the blade revolutions (Figure 2-12).

FIGURE 2-12 A great horned owl perches on a 65-kilowatt Micon turbine during a low wind period at Altamont Pass in California. Scientists have learned to reduce the impacts of the technology on birds. Shawn Smallwood/DOE/NREL.

Do small wind turbines kill birds? Occasionally. Sure, that’s unfortunate, and not just because people tend to like the pretty winged things. Birds play critical roles in the ecosystem, and many species have seen stark declines over the past century or so. In working on this book, we did an informal survey of small wind owners and asked if any of them had ever encountered a dead bird at their tower. Most said no, although one person admitted to “seeing one,” and another “knew someone who had.”

What kills them? Collisions with turbine blades have been recorded, as have occasional collisions with towers. How much of a problem is this when it comes to small wind, and can it negatively impact the health of avian populations?

According to Karen Sinclair of the National Wind Technology Center, there is almost no reliable data that can answer those questions. Sinclair is one of NREL’s top researchers on the environmental impacts of wind turbines, and she told us that small wind owners should give the issue some thought.

“Everything has an impact, so the question from a societal standpoint is, what’s a tolerable impact?” Sinclair asked. “If you knowingly put something up that could impact a threatened species, then that’s a problem,” she added. In fact, Sinclair pointed to some small wind turbines that have been sited in important habitat for the endangered Indiana bat.

If you are considering a turbine, Sinclair says it’s first important to understand the nature of your site. “There’s a lot of literature out there on what species might be of concern in that area,” she explained. This is important, because species can differ in their vulnerability to collisions, as well as in the health of their local populations. “It’s not likely that the flight patterns of condors would put them in conflict with small wind, but that could be an issue with commercial wind farms,” Sinclair explains as an example.

Sinclair suggests checking in with your local Audubon Society chapter and natural resources office to see if there are any known species at risk. “Maybe soon there will be maps available to small wind installers [that show species of concern],” said Sinclair. “We know that thousands of small turbines are installed and they don’t go through the rigors of commercial wind farms. But there is concern on the part of the U.S. Fish and Wildlife Service.”

Sinclair points out that when her U.S. team installs a small wind turbine with federal money, the project has to go through a National Environmental Policy Act (NEPA) review. This involves a pretty comprehensive checklist, covering any potential impacts on wetlands, cultural history, water, and a host of other facts. “We’re not saying people have to do a full NEPA review, but they should think about what the impacts could be,” said Sinclair. “Remember, all impacts are site specific. These turbines are not a benign technology, and the industry needs to be thoughtful and proactive.”

If we look at birds, its helpful to note that total bird mortality in the United States is estimated at 1 billion animals per year.³¹ Recent data show wind turbines account for less than 0.003 percent of all annual U.S. bird fatalities—and most of that tiny percentage is attributed to utility wind farms. So clearly, bird deaths caused by wind turbines are a minute fraction of the total anthropogenic bird deaths.

Having said this, in Table 2-1 we provide U.S. estimates summarized by Erickson et al. (2005) and the U.S. Fish and Wildlife Service. Those sources emphasize the uncertainty in the estimates, but the numbers are so large that they are not overly obscured by the uncertainty.

TABLE 2-1 In the scope of human influence, wind turbines represent a vanishingly small threat to birds. That doesn’t mean the industry isn’t taking the issue seriously, however, and taking steps to reduce impact further.

There is currently no evidence that fatalities caused by wind turbines result in measurable demographic changes to bird populations, with the possible exception of raptor fatalities in the first wind farm in Altamont Pass, California. There an estimated 1,300 raptors are killed annually, among them 70 golden eagles, which are federally protected.³²

The probability of bird fatality is affected by both abundance and behavior of the species. Small songbirds that migrate at night are the most common fatalities at wind-energy facilities, probably due to their abundance and the fact that they can’t see obstacles as well after dark. However, fatalities probably have greater detrimental effects on raptor populations because of their characteristically long life spans, low reproductive rates, and low abundances. Interestingly, long-lived geese and ducks have seemed to do a good job detecting and avoiding wind farms.

Experts agree that more research needs to be done on the potential impacts of turbines on birds. Remote technology could be used to monitor collisions, which could lead to new mitigation measures.³³

Some progress has already been made. Newer, larger turbines appear to cause fewer raptor fatalities, likely due to higher towers and larger blades, which move slower.

Going further, some research has been done on making blades more visible to raptors. “There was some indication that one black blade and two white blades made them more visible,” Sinclair explained. However, she cautioned that the concept may not apply to small turbines, which spin relatively faster.

It has long been known that wind turbines attract insects, which in turn bring birds within range of the spinning blades. Scientists have discovered that by tinting the blades the color purple, it seems to reduce the number of insects that are attracted during the day and at night.

More work is also being done to study the flight pattern of coastal birds, including a project at the Rødsand II wind farm in Denmark. Researchers have generated what is called a theoretical maximum distance (TMD) from the coast for raptor species. If the nearest turbine of a marine wind farm is placed farther away from the coast than the estimated TMD, the collision risk would be reduced.³⁴ Again, this doesn’t necessarily apply directly to your backyard wind turbine, but it’s good to be aware of.

It’s worth revisiting the infamous example of Altamont (Figure 2-13). It is commonly repeated in the popular press that one of the reasons for the wind farm’s high reported bird fatalities was the lattice structure of the towers, which allegedly attracted birds to nest and perch on them. However, according to Sinclair, more recent analysis of the data suggests that was never the problem. (Incidentally, we also asked small wind turbine owners if they had ever seen birds nesting in their towers, and they all said no.)

FIGURE 2-13 A golden eagle soars above a 100-kilowatt wind turbine at Altamont Pass in northern California. One of the oldest wind farms, Altamont has a reputation for killing raptors, although engineers have been redesigning the site. Shawn Smallwood/DOE/NREL.

According to Sinclair, the reason abundant turkey vultures were not being killed at Altamont but raptors were boils down to behavior. “Red-tailed hawks were at greater risk at Altamont because there were rock piles that had been moved to make way for the turbines, and they provided habitat for California ground squirrels, which the hawks hunt,” explained Sinclair. “During foraging, they collided with the turbines.”

In sum, wind turbines seem to have a relatively insignificant effect on bird populations, predictably more so with small turbines. If you are comfortable keeping your cat, living in a building with windows, using electricity supplied by hightension wires, driving in your car, and talking on your cell phone, you can rest assured that your wind turbine is vastly less harmful and provides more ecological benefit.

Still, one more thing to keep in mind is that if you are considering an installation, it’s a good idea to factor in how construction and maintenance may alter the ecosystem through vegetation clearing, soil disruption, and potential for erosion. This could result in fragmentation and loss of habitat for some bird species or their prey. Try to avoid creating rock piles next to the turbine that might attract ground squirrels.

If bird fatalities still remain a sensitive issue for you or your community, you could conduct pre-siting and post-siting studies. It is relatively expensive and time-consuming, but it would provide helpful information. At a minimum, before you build, try to find out what species are in your area and if their behavior may put them at risk (Figure 2-14).

FIGURE 2-14 Hoary bats (Lasiurus cinereus) seem to be the most common species killed by commercial wind turbines, and scientists think the culprit may be near-contact barotrauma—lung failure from abrupt pressure change. Paul Cryan/U.S. Geological Survey.

Impacts on Bats

Although bats might not be everyone’s favorite flying creatures, it is important to remember that these bug vacuums reduce insect populations during birds’ off-hours, making life more bearable for us (and saving you money on bug spray). Although there isn’t a lot of conclusive data to adequately evaluate the effects of turbines on bats, there is some evidence that commercial projects may be having a negative effect, and some scientists are concerned (Figures 2-14 and 2-15).

FIGURE 2-15 U.S. Geological Survey (USGS) biologist Paul Cryan is studying bat fatalities at large wind turbines. Little is known about potential impacts of small turbines, but so far there is little evidence of harm. Paul Cryan/U.S. Geological Survey.

Recent studies have found significant deaths of migratory, tree-roosting bats at utility wind power facilities in forested regions of eastern North America.^{35, 36, 37} A study in Pennsylvania and West Virginia reported 466 dead bats in 42 days (11.1 bats/night or 0.26 bats/turbine/night) as a result of collisions with large wind turbines.³⁸ This does not suggest that all areas and all turbines may see similar results. However, these fatalities have a greater detrimental effect on bat populations because of their relatively long life spans and low reproductive rates.³⁹

Data on small wind effects on bat populations are sparse. According to Sinclair, the U.S. Fish and Wildlife Service is concerned about potential impacts of small wind turbines on the endangered Indiana bat. “They’re taking a very conservative perspective and saying, ‘Don’t put small turbines in these areas,’ even though there’s no data,” Sinclair explained. She added that there is some concern that bats may be more at risk than birds because of the altitude at which they commonly fly. (They also tend to fly at night.)

Given that bats use echolocation and generally detect moving objects better than stationary ones, it may seem surprising that they would run into turbines. A number of theories have been proposed to explain it, including that bats may be attracted to ultrasonic sounds produced by turbines, to bugs that congregate around turbine lights, or to the cleared land around towers. Some scientists have suggested that many bats may be killed not by striking turbines directly, but by the sudden differences in air pressure around them, in a process called near-contact barotrauma. The change in pressure is thought to result in internal bleeding, and bats are thought to be more susceptible than birds. Further, it is thought that bats are unable to detect the sudden pressure changes.⁴⁰

In any case, migratory tree-roosting (they-sit-in-trees) and insectivorous (theyeatinsects) species of bats—such as hoary bats—appear to be the most susceptible to trouble around wind turbines (Figure 2-16). Another hypothesis is that bats view these tall structures as roost trees.^{41, 42, 43}

FIGURE 2-16 Most of the concern for birds and bats revolves around large utility-scale wind farms like this one near Bickelton, Washington, but that doesn’t mean small wind installers shouldn’t give any thought to potential impacts. Iberdrola Renewables/DOE/NREL.

Clearly, more research is needed on the impacts of wind turbines on these bug vacuums. In the meantime, there are some things you can do to minimize risk. Contact your local bat conservatory association for migrating patterns in your region, and change the location of the turbine if need be. In addition, you might also consider looking into one of these emerging strategies: (1) color, (2) electromagnetic frequency, (3) periodic shut-down, or feathering.

As we mentioned in the section on birds, painting or tinting the turbine system purple may help make it less attractive to insects, and therefore bats.⁴⁴ In other studies, applied electromagnetic fields seemed to keep bats away (but not pesky insects).⁴⁵ Bat deaths might also be reduced by feathering the turbine blades (changing their pitch angle) or slowing or stopping rotation during short periods of high bat activity.⁴⁶

Another interesting idea comes from a biologist with Bat Conservation International, Ed Arnett, who suggests raising the cut-in speed, or the wind speed at which wind turbines switch on, to 11 mph. According to Arnett, bats usually don’t fly when it’s too windy. In his trial, bat fatalities were reduced up to 93 percent, while annual energy output loss was reportedly less than 1 percent.⁴⁷ Admittedly, you’d need to have a great wind resource to have the flexibility to do that.

Summary

Wind turbines have many benefits, but they also have some limitations and challenges. There is also a lot of misinformation about them. As author Paul Gipe told us, “They’ll always be somebody who says it’s going to electrocute them or make their hair fall out. Twenty-five years ago, people in the Mojave Desert were afraid wind turbines would make rattlesnakes come out. Others have accused wind turbines of shocking the teats of their cows [through automatic milkers].” In case you are worried, according to Gipe, the latter effect is the result of improperly grounded barn electricity, not renewable energy.

It’s more than likely that you now know more about wind power than most of your neighbors, angry though they may be. They will need some form of education, and you can get them started, with this book as your primer. It’s definitely a good idea to be respectful of your neighbors. “If you create a bad vibe, it just takes one person to create a major barrier down the road,” Sinclair warns.

The next page includes this information in a brief table (Table 2-2), and as noted, most of these issues will not apply to your small wind turbine. But as an enthusiast of wind power, you have absorbed quite a bit of information in these pages, and found a few kernels that might have surprised you. What kind of images do your conscientious neighbors and community have about wind turbines? The probability is that they are more likely to generalize all wind turbines in a bunch. They will need some form of education, and you can help.

So, it has been a long trip on your second wind.

TABLE 2-2 Environmental Impacts of Small Wind Turbines

The following is a quick list of common challenges of wind turbine projects. Please use this information when issues arise about the installation of micro-to commercial-size wind turbines.