CHAPTER 12
Future Developments in Wind Power

There is nothing new under the sun, but the sun begets the wind, whose unyielding, unpredictable force unearths what was once hidden.

—KEVIN SHEA

Wind technology is constantly evolving, with new frontiers of research being explored in multimillion-dollar industrial and university labs as well as in the garages of tinkerers. This chapter takes a look at some of these emerging designs, with an eye toward what may be powering the future, whether that’s rotating blimps or carouseling kites flying thousands of feet up in the air.

Although research is ongoing and field tests are limited, we’ll try to give some insight into the feasibility and limitations of such cutting-edge systems when it comes to small-scale applications, the subject of this book. Some of these new designs show definite potential, while others call for the invention of smart wallets that automatically lock up when sensing the presence of unfeasible technology.

One word of caution: although we enjoy reading about novel designs as much as anyone, we would advise against getting out your credit card and ordering your very own experimental wind turbine. Most of the technology in this chapter is at best unproven, if not totally speculative. If you have the time, money, and desire to serve as a test case, we salute you, and may the winds of invention blow great success in your direction. But if you are like the rest of us, on a budget and interested in producing some clean kilowatts today, we strongly recommend that you stick with a tried and true design that’s backed up with years of real performance data, manufacturer warranties, and a support network.

That exotic machine with 28 scissoring, helium-filled blades may look awesome when you first nail it to your roof, but what happens when a storm breaks it in half, or the complicated electronics go on the fritz?

Architectural Wind: Can Buildings Improve Wind Conditions?

We placed this section on so-called architectural wind in the future tech chapter, because although a few examples do exist “in the field” and the idea has received considerable media attention, the concept is unproven, and likely needs more refinement if it is ever going to contribute to meaningful amounts of energy. The term architectural wind refers to the fact that moving air often accelerates as it rushes past large buildings, leading enterprising people to wonder if they could harvest this energy with well-placed small wind turbines.

Up until recently, the dominant player in architectural wind was the California-based company AeroVironment, which was founded in 1971 by famed inventor and aeronautical engineer Paul B. MacCready, Jr. MacCready is perhaps best known for co-creating the Gossamer Condor, a pioneering human-powered aircraft. His follow-up, the Gossamer Albatross, became the first human-powered airplane to cross the English Channel. MacCready helped NASA develop solar-powered airplanes, and he helped General Motors build the prize-winning Sunraycer solar car and the ill-fated EV-1 electric car (star of the documentary Who Killed the Electric Car?). MacCready also built a working replica of the pterosaur Quetzalcoatlus for the Smithsonian, which received considerable media attention.

Today, AeroVironment is a public company that makes unmanned surveillance aircraft (aka drones) and various advanced power systems, including chargers for electric cars. As of this writing, they are installing home chargers for the Nissan Leaf, with the first customer having been ubercyclist Lance Armstrong. AeroVironment also recently flew a prototype of the first airplane powered by hydrogen fuel cells, the Global Observer. According to Steve Gitlin, AeroVironment’s vice president of marketing strategies and communications, the company’s name refers to the goal of taking aerospace technologies and applying them to the environment.

In recent years, AeroVironment has also been in the business of measuring air quality. In addition to monitoring pollution, the company has helped wind farms evaluate their potential resource. Given this pedigree, it’s perhaps not surprising that the company made the move into small wind turbines in 2004.

AeroVironment’s sleek, five-bladed AVX 1000 (1 kW) turbines were specifically designed to take advantage of architectural wind (Figure 12-1), which the company claimed would “increase the turbines’ electrical power generation by more than 50 percent compared to the power generation that would result from systems situated outside of the acceleration zone.”

FIGURE 12-1 AeroVironment AVX 1000 (1 kW) wind turbines installed on the roof of a “green” building at the Brooklyn Navy Yard. These “architectural wind” turbines were discontinued after buyers reported low energy production. Brian Clark Howard.

The small, compact turbines were also intended to provide a “visible, compelling, and architecturally enhancing statement of the building’s commitment to renewable energy.” Twenty high-profile installations were made, including at Boston’s Logan Airport, on an office building at the revitalized Brooklyn Navy Yard, on top of The School of Sustainability at Arizona State University, and on the roof of a Kettle Foods potato chip factory in Beloit, Wisconsin. The small, aviation-inspired turbines are extremely quiet and relatively easy to install, thanks to their modular design.

Perhaps not surprisingly, the AVX turbines earned several design awards, as well as thousands of inches of coverage in print and online. “They were very positively received,” Steve Gitlin told us in an in-person interview in New York, at the LEED Gold–certified Hearst Tower (home of The Daily Green). “People loved them,” said Gitlin.

However, despite their buzz and sexy profile, there was a problem with the AVX 1000. It turned out that the installed turbines were producing only small amounts of energy for their owners. In a scathing presentation, wind installer, author, and consultant Mick Sagrillo estimated that the 20-turbine Logan installation would take thousands of years to pay for itself. Paul Gipe calculated that the dimensions of the turbines—a “width” of 72 inches (1.83 meters) and swept area of 2.6 square meters—should be expected to produce a rating of 500 watts, half the manufacturer’s claim.

For his part, Gitlin told us, “They produce electricity, but not at a rate that is economically viable.” He added, “People want to go green, but they also want to make electricity.” Could that be a motto for this book?

Gitlin told us his company would have little trouble selling more of the turbines if they wanted to, but he said they recently made the conscious decision to put the product “on the back burner.” Asked if there was a problem with the architectural wind effect itself, Gitlin responded, “There is acceleration, but not enough when you take into account the cost.”

That cost was pretty substantial for the businesses that bought AVX 1000 turbines. An apartment building in the Bronx spent about $100,000 for a ten-turbine AVX 1000 installation on its roof. The idea was to generate power that could be used for the building’s hallways, elevators, and common areas. However, the results have been disappointing, according to Les Bluestone, principal for the developer, Blue Sea Development.

“If the wind was blowing consistently enough it could feasibly do that, but ‘if’ is a big question,” Bluestone told us via phone. “We’ve found that winds have not been as consistent as we would have liked them to be to make payback reasonable.” Bluestone admitted that the decision to install wind turbines had been “an experiment,” and he added, “It’s a little too early to tell, but I would guess we would not rush into it again.” Bluestone added that they had known their wind resource was “a bit iffy,” from looking at NOAA data, although he said they didn’t do any long-term data collection themselves.

“We’re in a very urban setting, with only a little bit of clearance, and there are all sorts of things that work against us,” Bluestone said. “This particular product takes advantage of updrafts up buildings, so we thought this was our best shot rather than trying to use a vertical axis or conventional turbine. But for our application there’s still not enough wind.”

When asked what the community thinks of the turbines, Bluestone said they’re very popular. “When they’re spinning everyone is in awe, and when they’re not some people ask if they’re fans to cool the neighborhood. People like them, and I haven’t heard any negatives,” said Bluestone.

“If we were going to [install the turbines] again we would have to have much more data before we would make that decision,” Bluestone concluded. He added that he was frustrated that AeroVironment is no longer manufacturing or supporting the turbines, and said he didn’t know what they’d do if they have a problem.

The disappointing results of the AVX 1000 in the field don’t necessarily prove that architectural wind will never work, but they do underscore the challenges of trying to harvest wind energy in an urban environment. As you should know now, wind speed is critical to the success of any wind turbine, regardless of what it looks like or where it is placed. Although it’s true that there can be an acceleration of wind around obstacles, like buildings or cliffs, it also tends to be true that the less flat the surface, the more turbulence you have (which is bad), and the more likely winds coming from other directions will get deflected.

A number of designers have recently proposed other turbine systems that purport to channel wind around buildings, sometimes with tunnels, flues, or other structures. It’s possible some configuration could work, but the site’s wind resource would have to be really strong to compensate for the expense of additional materials. Most likely, the owner would be better served by going higher, into unimpeded winds, rather than trying to wrangle fickle winds around buildings.

Others have proposed adding small turbines between large generators on wind farms, or lower on their massive towers. Although the idea of wringing more energy out of a utility turbine may sound appealing, it’s also true that wind farms take major capital investments, and few owners are going to want to risk damaging or hampering their main rotors by tinkering with unproven schemes. Lots of testing will need to be done.

Building Integrated Wind Turbines

In the aftermath of September 11, a number of bold designs were suggested for a new building at Ground Zero, for what was then going to be called the Freedom Tower. One of the more memorable proposals included several wind turbines, hung many stories above the city in a space between adjacent parts of the skyscraper. To many bloggers, the symbolism wasn’t subtle. This was a bold statement against our fossil fuel–reliant past and the dirty dealings with unstable regimes that it required. This was a symbol of hope for a cleaner, freer future.

Of course, it didn’t take long for skeptics to point out that the turbines would provide only a fraction of the massive tower’s energy needs. There were also concerns about cost, safety, and maintenance, especially since the guy who walked between the Twin Towers on a tightrope in the 1970s is getting on in years.

The plan for so-called building-integrated wind at Ground Zero was scrapped, but the concept has lived on, starting at the site of another world trade center. In 2008, the 50-story twin towers of the Bahrain World Trade Center went up in the Middle East. The towers are linked via three skybridges, each of which supports a 95-foot-diameter, 225 kW wind turbine (Figure 12-2). The turbines face north, where prevailing winds blow from the Persian Gulf. In an example of architectural wind, the sail-shaped towers are designed to funnel and accelerate the wind.

FIGURE 12-2 The 50-story twin towers of the Bahrain World Trade Center boast three 95-foot-diameter, 225-kW wind turbines, oriented to catch breezes off the Persian Gulf. Tim Miller/Wikimedia Commons.

The building’s designers hope the turbines will provide 11 to 15 percent of the towers’ total power consumption, or approximately 1.1 to 1.3 GWh a year. That’s roughly enough power to light 300 homes for a year. As of this writing, actual performance data is hard to come by.

In London, a 43-story residential high-rise was recently built with three building-integrated turbines. The building is officially known as Strata SE1, though it is often called the Razor, since it looks like a giant Norelco, with the turbines on top resembling shaving blades (Figure 12-3). The nine-meter turbines are rated at 19 kW each and are hoped to produce 50 MWh of electricity per year, enough for the common areas (8 percent of total building energy). Though the tower was completed in 2010, the turbines are undergoing ongoing testing, so actual performance data isn’t available.

FIGURE 12-3 London’s Strata SE1, often called “the Razor,” hosts three 19 kW integrated wind turbines, which are hoped to produce about 8 percent of building energy. Skyscrapercity User: SE9/Wikimedia Commons.

In the past year, a number of other building-integrated wind projects have been announced. The appeal is obvious, although the expense is considerable, and the results unproven. It’s possible that we may one day see a turbine as part of every building, but that seems pretty unlikely, given the limitations of current technology and the poor wind quality of most neighborhoods.

Long-time green building writer Alex Wilson recently wrote, “I want to like building-integrated wind. There’s a wonderful synergy in the idea of combining form and function by generating electricity with turbines that reach into the sky on the buildings they will help to power. But in most cases, at least with today’s technology, it just doesn’t make sense …”

Biomimicry: Wind Systems Inspired by Animals

Some new experimental wind turbines borrow directly from nature, in a design process now called biomimicry—literally mimicking life. Examples of biomimicry in action include buildings that use passive cooling based on the architecture of termite mounds, adhesives based on the natural secretions of mollusks, and coatings that naturally repel dirt based on the texture of the lotus flower.

When it comes to wind turbines, the Toronto-based company WhalePower is marketing blades modeled after the flippers of humpback whales (Figure 12-4). The idea is based on research done at Harvard and elsewhere on the bumps, called tubercles, on the leading edge of humpback flippers. The tubercles are thought to help reduce stall when gliding through the water, and therefore increase speed and make the giant mammals more agile. This discovery led researchers to suggest that tubercles could make airplanes easier to control and fans more efficient.

FIGURE 12-4a Toronto-based WhalePower is working on wind turbine blades with bumps, called tubercles, modeled after the flippers of humpback whales. Joseph Subirana/WhalePower.

FIGURE 12-4b Tubercles are thought to increase speed and decrease stall. Whit Welles/Wikimedia Commons.

WhalePower claims adding tubercles to wind turbine blades would reduce noise, increase stability, and improve energy performance up to 20 percent overall. The company says the bumps work by channeling the airflow and reducing stalling, just like a whale flipper in water. Theoretically, this means turbine blades can have steeper attack angles, and therefore draw more power out of the wind. WhalePower says tests show the bumps double performance at wind speeds of 17 miles per hour, and also help turbines capture more energy out of lower-speed winds.

WhalePower says existing wind turbine blades can be retrofitted with tubercles, in a process the company says makes the hardware even sturdier. We asked a representative of the company on when we might expect the technology.

Danielle Dewar told us WhalePower is currently working on small fans (Figure 12-5), computer fans, and large and small wind turbines. “These products are not yet commercialized, but we hope that they will be over the next 18 months to two years,” Dewar explained over e-mail.

FIGURE 12-5 WhalePower’s first commercial product, the Envira-North Altra Air Fan, also borrows from whale flippers. Joseph Subirana/WhalePower.

So, in the near future, you may be able to buy a turbine inspired by a whale … or maybe even something smaller.

A recent paper from researchers at the California Institute of Technology argued that planners of future vertical axis wind farms might do well to mimic the schooling patterns of fish. Robert W. Whittlesey and colleagues pointed out that spacing horizontal axis wind turbines too close together results in decreased performance, while that effect is diminished with VAWTs.

Publishing in the peer-reviewed journal Biosinspiration and Biomimetics, Whittlesey’s team concluded, “A geometric arrangement based on the configuration of shed vortices in the wake of schooling fish is shown to significantly increase the array performance coefficient based upon an array of 16 × 16 wind turbines. The results suggest increases in power output of over one order of magnitude for a given area of land as compared to HAWTs.”

There aren’t really any vertical axis wind farms around, for a number of reasons we covered earlier in this book. But the scientist’s research suggests they may one day play a role, possibly even at a small scale.

Let’s Go Fly a Wind Turbine

Since you already know that wind tends to get stronger and more consistent the higher up you go from the Earth’s surface, it would seem like an obvious invitation to loft a turbine into the heavens. In fact, a lot of designers have taken a crack at the idea and Google has invested $10 million into research, though the practical challenges remain formidable, and there are few working examples.

Still, so-called airborne wind energy has its boosters. Joe Faust, editor of UpperWindPower.com, told us, “Trees and towers sit in the boundary zone where little wind occurs; above the boundary zone is a vast resource that is thick, steady, predictable, fast, accessible, cleaner, and minable without tall expensive towers; the power affected by the velocity-cube law combined with those aspects opens a game-changer for wind energy via traction, task, and direct-electricity generation. A new aviation is being born.”

Of course, to harvest airborne wind energy, you probably have to get the power down to the ground, where it is useful. As you may know by now, wire isn’t that cheap, especially when you are talking hundreds of feet. Sure, you could try to beam the power down via microwaves or lasers, but that technology is currently expensive. That may be an option in the future, however. There are obvious safety concerns with lifting electricity generators above our heads, and no one wants to see their investment come crashing down. Pilots may also have a few concerns. So there are some issues to work out, but supporters of airborne wind energy argue that the challenges are solvable, and that the benefits of reaching strong winds will eventually outweigh the challenges.

Cristina L. Archer has studied the potential of high winds in her role as an Assistant Professor in the Department of Geological and Environmental Sciences at California State University, Chico. She told us via email, “Wind speeds can easily double between 100 and 500 meters above the ground, which causes a growth in the available power by up to 8 times. I found that between 500 m and 2000 m there is not much growth (on average), but actually above 2,000 m you get rapid gradients of winds, with the jet streams being La Mecca of winds.”

Archer told us she envisions a huge benefit in reaching the 500-meter height. “The same turbine would generate up to 8 times more there (the exact amount depends on the actual wind and air density, turbine design, and efficiencies, etc.),” she said. “Not to mention that it would be cheaper, lighter, and generally have a higher capacity factor due to the lower (although not insignificant) intermittency of winds.” Archer is currently working on mapping jet stream currents around the world that appear between 300 and 2,000 meters above the ground.

It’s certainly possible that new designs and advances in electronics and materials science will one day have us harvesting energy from floating turbines. Bryan Roberts, a professor of engineering at the University of Technology in Sydney, Australia, has proposed a helicopter-like turbine craft that would fly to 15,000 feet (4,600 m) altitude, where it would allegedly hover in place, buoyed by lift generated by action of the constant wind. It would be anchored to the ground by a very long cable.

Dutch ex-astronaut and physicist Wubbo Ockels has proposed a “Laddermill,” a big loop of kites that generates power as one end of the kites lifts itself up, as if climbing an endless ladder in the sky. In Italy, inventor Massimo Ippolito is building a prototype of his Kite Gen idea, which he says was inspired by watching kite-surfing. Big airfoils will be lofted into the sky, and tethered to a vertical shaft, which will generate energy as it rotates (Figure 12-6). A computer will control the airfoils to keep them optimally turned into the high winds.

FIGURE 12-6 Inspired by kitesurfing, Kite Gen’s airfoils will be tethered to a vertical shaft, which will generate energy as it rotates. Kite Gen Research.

Another Italian company, Twind Technology, promotes a concept of two tethered balloons, each with an inflatable sail. They would take turns being pulled by the wind, and thereby move a shaft or other mechanical device on the ground, to make power or do work like sawing.

One of the more well-known attempts in the space is by Magenn Power, which has offices in California and Ontario, Canada. The company is currently taking pre-orders for its 100 kW Magenn Air Rotor System (MARS), a helium-filled mini blimp that is designed to float up to 1,000 feet (Figure 12-7). When wind hits its fins, the cylindrical body rotates around a horizontal axis, generating electricity that it sends down the tether wire.

FIGURE 12-7 The 100 kW Magenn Air Rotor System (MARS) is a helium-filled mini blimp designed to float up to 1,000 feet. When wind hits its fins, the cylindrical body rotates, generating electricity that goes down the tether. Magenn Power.

The MARS system is said to stay especially stable in the air, and is said to meet FAA guidelines for airspace safety. The company is promoting it for use on oil rigs, in wilderness areas and other remote applications. As of this writing, pricing has not been announced.

Rival turbine designer Doug Selsam (see more below) has criticized the MARS design, and told us their turbine looks inherently inefficient. Magenn did not respond to repeated requests for comment.

Closer to the utility scale, California’s Makani Power claims to be developing a 1 MW airborne wind energy system, thanks in part to a $10 million investment from nearby Google. Makani’s 10 kW prototype is an airplane-shaped kite that flies in circles, while wing-mounted rotors extract energy and send it down a tether (Figure 12-8).

FIGURE 12-8 Makani Power’s 10 kW prototype is an airplane-shaped kite that flies in circles, while wing-mounted rotors extract energy and send it down a tether. Makani Power.

Makani also declined to comment for this book.

Supporters say airborne wind holds great potential, so in a few years, you may be able to order a floating turbine from a catalog, and tether it to your cabin for hours of free juice. But until they are more widely tested, you’ll likely have to keep your dreams more firmly anchored on the ground.

INTERCONNECT

WindMade Label Makes Supporting Clean Energy Easy as Shopping

Consumers will soon have another option to support wind power, without having to give any thought to towers, inverters, or wind patterns. They can simply do what consumers already do best: shop.

Just as shoppers can now support sustainable agriculture by choosing certified organic foods, or support just labor practices by looking for the Fair Trade seal, people will soon be able to buy products marked with a WindMade logo (Figure 12-9). As of this writing, the precise details of the program are still being worked out, but the founders hope WindMade will achieve global adoption, and that it will help support new wind energy capacity.

FIGURE 12-9 An ambitious new global label hopes consumers will choose products marked as “made with wind power.” The idea is to raise funds for new wind farms. WindMade.

WindMade was the brainchild of Morten Albaek, senior vice president for global marketing of Denmark’s Vestas, the world’s largest wind turbine manufacturer. Vestas provided startup funding to WindMade.org, the independent nonprofit that will actually administer the program. Certifications will be audited by PricewaterhouseCoopers, another founding partner. Other partners include the World Wildlife Fund, the UN Global Compact, Lego (yes, the toy maker), Bloomberg, and the Global Wind Energy Council.

When we met with Albaek in New York in winter 2011, he told us the WindMade working group was considering launching with a minimum requirement that 12.5 percent of a product’s energy footprint must come from wind, at least for initial certification. Albaek said they were hoping to be able to increase the requirement over time, and to eventually list the amount used for each product. Albaek also noted that they hoped to be able to certify whole companies, starting with a baseline of 5 percent of their operations powered by wind energy, “with a commitment to a fairly ambitious target to increase the amount of renewables used,” he said.

According to Albaek, WindMade would require a significant percentage of wind energy to come from new installations (probably turbines placed in service within two years). “This ensures we have more going into the grid,” he said. Albaek also added that he was hoping fees collected by WindMade could be put toward new wind farms in the developing world, “so they can avoid the same mistakes as us.”

It’s not hard to see why Vestas and others in the wind industry would be behind WindMade, since it has the potential to stimulate growth, or at least drive awareness of their business. For his part, Albaek hopes the program can become a model for other types of renewable energy. He added, “There’s also a reason why wind is first; it’s the most mature, developed, and organized clean energy.”

It’s an open question whether consumers will embrace the WindMade label, and if it will become powerful enough to actually influence purchasing decisions. Thousands of progressive labeling schemes have been launched around the world over the years, for everything from green hotels to less toxic dry cleaners. Most of these labels remain locally focused and niche players, although a few have broken into the global consciousness. But even if WindMade doesn’t become as big as certified organic food, it can still become a viable way for consumers to support the wind industry.

Ultra-Micro Wind Turbines

If a tiny solar cell can readily power a watch or a calculator, why can’t a tiny turbine charge up your cell phone? Actually, such products already exist, which we’ll get to shortly. Still, current ultra-small turbines are essentially novelties, or at best prototypes. The small WePOWER turbines on the Ricoh ad in Times Square didn’t last long, if they ever were installed in the first place. Not many sites on buildings are likely to have very good wind.

Still, if tiny turbines could be scaled up massively, could they make an impact?

The Hip HYmini

Billed as a portable charger for the active lifestyle, the HYmini is a sleek, handheld device that can charge cell phones or other small 5V electronics (Figure 12-10). Made by MINIWIZ Sustainable Energy Dev, the HYmini has an onboard lithiumion battery pack that can hold a charge from a wall outlet (ho-hum) or from renewable energy (yay!).

FIGURE 12-10 The sleek, handheld HYmini is designed to power portable devices with the power of the wind or sun. MINIWIZ Sustainable Energy Dev.

The product comes with a small external solar cell; or you can blow away your friends by charging with the built-in micro-turbine, which cuts in with 9 mph breezes. It glows green when charging; how cool is that?

It’s difficult to gauge how much power can actually be produced by the tiny turbine, though the manufacturer’s claims that it is “supplemental” are perhaps telling. Some consumers have complained that it takes a lot of wind to be able to charge a phone, and they question the practicality of the product. (Some people have taken to driving around town with a HYmini strapped to their roof, though it’s unclear if the power produced offsets the fuel cost resulting from additional drag.)

To skeptics, products like this discredit the renewable energy industry and fail to even pay back their embodied energy of production and shipping. To boosters, they educate the public about the possibilities of going greener. Funny, some say the same thing about small wind systems.

Tiny Piezoelectric Wind Turbines

You may have heard a news report about dance floors that harness energy through the stomping of feet, or speed bumps at drive-through restaurants that power lights by the passing of cars. Such motion-based energy harvesting works by taking advantage of the piezoelectric effect, which occurs when certain solids, typically crystals, emit a small amount of electricity after being placed under strain.

The precise electromagnetic properties that result in this phenomenon are beyond the scope of this book, but suffice it to say that inventers have envisioned tiny piezoelectric wind turbines, on the scale of centimeters, that produce electricity by flexing piezoelectric crystals as they rotate. According to Nature News, such tiny turbines would be 18 percent more efficient than if they harvested energy through a standard electrical and mechanical generator.

One potential application would be powering small electronic devices as stand-alones or perhaps as a finely distributed network.

The Windbelt

At the 2007 Popular Mechanics Breakthrough Awards ceremony, young inventor Shawn Frayne caused a sensation with his simple, ultra-small wind device, which he dubbed the Windbelt (Figure 12-11). Frayne’s device is built from off-the-shelf parts that cost only a few dollars, and it is said to generate 40 mW in 10 mph winds. Power is generated by the fluttering of the belt, which causes a pair of magnets fitted on a membrane to oscillate between two wire coils.

FIGURE 12-11 Young inventor Shawn Frayne examines his inexpensive Windbelt, which generates 40 mW in 10 mph winds. Frayne hopes the technology will be useful in the developing world. Humdinger Wind Energy.

Frayne envisioned the Windbelt as more than a toy, although it is a pretty nifty one. He hopes that it can be used in isolated communities in developing countries as an affordable source of power for lights, charging cell phones, or other small loads. He is currently working on larger and more efficient designs.

Traffic Turbines

Some clever folks have wondered if we could get energy out of the “wind” produced by moving cars, trucks, and trains (Figure 12-12). It’s a nice idea, but you should know by now that such wind is likely to be highly turbulent and intermittent. Current technology is unlikely to be able to harvest enough energy over time to recoup an investment in equipment, but it’s possible that such a scheme could work in the future, perhaps if turbines get cheap enough.

That would be good news for Tokyo drifters.

FIGURE 12-12 Some designers wonder if we can harvest the wind created by moving traffic. It seems like it would be highly turbulent and intermittent, but if turbines can become cheap enough one day…. Quietrevolution.

Alternative Turbine Designs

It sometimes seems that every engineer and their brother has an idea for an “alternative” wind turbine that promises to be “more efficient,” quieter, more bird-friendly, or some other superlative. As we have pointed out, there is no way to cheat nature, and it seems unlikely that any technology will beat the Betz limit of harvesting 59.3 percent of the kinetic energy from the wind.

But that hasn’t stopped inventors from trying, and the Internet is full of images of oddly shaped turbines. If you want to try your hand at inventing the next design, by all means go ahead. But be aware that few have succeeded.

In the next section, we take a look at a couple of the more interesting recent alternative designs, both of which have garnered significant press.

RidgeBlade

A startup company in North Yorkshire, England, called The Power Collective won the Netherlands’ 500,000-euro Postcode Lottery Green Challenge in 2009 for its RidgeBlade design, a low-slung wind generator intended to hug the peaks of rooftops, even in urban areas. With its wind-channeling louvers, the RidgeBlade resembles a hotel air conditioning unit or a bat house.

We hope this book has taught you to be skeptical of design awards, which often reward novelty, not real-world energy production. The Power Collective isn’t releasing any energy or price data at the time of this writing, but the group claims it will be going into production of a small run of products in the near future.

On their website, The Power Collective writes:

In the past there has been a lack of confidence in small wind turbines, because some of the systems sold simply did not deliver the sort of output that was promised—we want to be absolutely sure that the RidgeBlade performs well, and we will be working closely with a well known UK university to provide external verification of all our figures. Secondly, in the UK, we have a new requirement for all small wind turbines to be accredited under the MicroGeneration Certification Scheme (MCS) before they can be eligible for the generous feed-in tariffs, and this certification takes at least 12 months (and an awful lot of money)… What we can say is that we are quite confident that the RidgeBlade will pay for itself more quickly than any comparative technologies.

Will the RidgeBlade actually produce a meaningful amount of energy once installed on your roof? One potential red flag is that the company boasts it will start making energy in winds of 4 mph. As you should know by now, there is so little energy available in winds of that speed that it’s irrelevant. Further, the company admits that its device can’t yaw to face the winds, which are likely to be changing and turbulent on a roof.

As far as the underlying science, The Power Collective claims the RidgeBlade “uses the existing roof area to collect and focus the prevailing wind using the Aeolian wind focus effect. This is where the wind is forced to travel over the roof surface and forms a pinch point at the roof ridge, accelerating the airflow through the turbine.” The company claims this so-called effect boosts wind speed around the ridge two to three times.

We were unable to find any other references to the Aeolian wind focus effect online, and a representative from the company, Bernie Cook, declined to comment on it. The so-called effect sounds a lot like AeroVironment’s hopes for architectural wind, which clearly didn’t pan out, despite a significant investment by a company with decades of experience in the aerospace sector.

We asked Cook what he thought of AeroVironment’s failed project, and he claimed, “The RidgeBlade is a very different technology in terms of both concept and design, and we are currently engaged in a process of testing and assessment.” Cook said he couldn’t get into any more details of the RidgeBlade at this time, but indicated the company hoped to be ready to more openly discuss their technology in nine to twelve months.

He added, “Because micro-wind, as a sector, has suffered from controversy in recent times, we are committed to building a robust, third-party-verified set of real-world performance data before we start to communicate any outputs or commercial claims (other than that which is already in the public domain).”

Cook said, “We are working with a number of organizations that are keen to incorporate our technology into products, which is very much our preferred way of working—given our skill set and company strategy.”

Given AeroVironment’s experience and the fact that rooftops are usually high-turbulence zones—and at heights that normally do not give good wind speeds anyway—we’re highly skeptical of the RidgeBlade. However, we’d like to see independent field trials—and get our specific questions on turbulence, energy production, and so on answered—before passing further judgment.

The Honeywell/WindTronics “Blade Tip Power System” Turbine

Another unusual small wind generator that has received a lot of press, including a spot on the Today show and a Breakthrough Award from Popular Mechanics magazine, is the Honeywell WT6500 2.8 kW turbine (Figure 12-13). Made by Michigan-based WindTronics, the turbine is marketed under the Honeywell brand in North America, due to a licensing agreement. Calls to Honeywell International were not returned, but insiders say the Fortune 100 conglomerate had little to do with the design or marketing of the turbine that bears its name.

FIGURE 12-13 The Honeywell/WindTronics WT6500 2.8 kW turbine is a bold new design, but can it produce meaningful amounts of energy in the real world? Brian Clark Howard.

Outside of North America, the unique turbine is sold under the brand WindTronics. Note that the company is distinct from EarthTronics, which is also based in Muskegon, Michigan, and was founded by the same person, Imad Mahawili. EarthTronics also advertises the Honeywell turbine, and listed it as the “Earthtronics 760” at one point, but today focuses on lighting, medical equipment, and small motors. Mahawili, a chemical engineering PhD and wind energy consultant who grew up in Baghdad, invented the Honeywell turbine after being inspired by the 2004 Asian tsunami. His vision was an efficient, affordable generator that could one day help power the developing world.

WindTronics claims that its design “turns a wind turbine inside out.” The WT6500 uses many nylon blades, with a magnet attached to each blade tip. The stator is the ring around the outside of the generator, which has coils of copper inside. Mahawili’s idea was that the configuration would be inherently more efficient because it produces electricity in a single step, without a separate alternator.

At first glance, the WT6500 resembles the Éoliennes Bollée wind turbine patented by Ernest Sylvain Bollée in France in 1868. That design, also a HAWT with many blades arranged inside an outer ring, was the first to have wind pass through the blades of the stator before hitting the rotor. The Éoliennes Bollée was successful in France before widespread grid power, and numerous historic examples survive. Like the WT6500 today, the Éoliennes Bollée could yaw to face the wind or tip out of the wind under extreme conditions for protection.

As of this writing, about 50 Honeywell turbines have been installed, including one on the Solarium “green” apartment building in Queens (Figure 12-14). In a phone interview, Brian Levine, a co-founder of WindTronics and the vice president of business development and marketing, told us his company has an order backlog “in excess of $15 million.” Besides the head office in Michigan, the company has an R&D facility in Napa Valley and a new assembly plant in Windsor, Canada. Levine said the company has 50 to 60 employees, but has ambitious plans to set up more “modular” factories around the world.

FIGURE 12-14 A look through the back of the Honeywell/WindTronics turbine installed on the Solarium, a “green” apartment building in Long Island City, Queens. Brian Clark Howard.

According to a March 2010 report prepared for the Tulane University Climate Committee, a Honeywell turbine costs approximately $9,000 up front, with annual maintenance costs of $250. The six-foot-diameter machine weighs 170 pounds, and is “significantly smaller than classic horizontal-axis wind turbines,” according to the report. The estimated carbon reduction for each Honeywell turbine is 0.995 metric tons of carbon dioxide per year.

The Tulane report notes that Honeywell turbines are “designed to start generating electricity at 2 mph while high resistance traditional horizontal-axis turbines begin at 7 mph.” The report authors went on to explain that this was a “crucial feature,” given relatively low winds on campus. The authors failed to point out that there is actually very little energy in low winds, so the point is essentially moot. The authors did not question WindTronics’ claim that the turbine “need only be five feet above a roofline.”

The report indicated an average roof could support three WT6500 turbines, and that the suggested retail price was $5,995 each, plus an estimated $3,000 installation cost for each unit. The turbines are covered by a five-year warranty and are said to be designed to last 20 years.

Levine told us Mahawili’s design philosophy had been to break with what he called the problems of conventional turbines, which he said, “have to be really high, need a hell of a lot of wind, have impacts on animals, vibrate, and make noise.” Levine added, “What we’ve learned from users is that they’re concerned about noise, animals, vibration, and height. Those constraints have kept people from adopting this technology. I thought people would ask about ROI first, but they ask about that last. The first thing that drives them is whether it is feasible where they live, based on permits, neighbors, noise, and other constraints. Then they start looking at the economics.”

Levin said people like the fact that the blades seem shrouded inside the stator. “People tell us they’re scared of blades swirling in the background,” he said of more traditional wind turbines. “Our goal is to get the resistance and friction out of the turbine so it engages sooner and longer. That addressed these other issues: noise, height, vibration, etc.”

When pressed exactly how much resistance and friction were reduced, Levin said, “It has to do with the fact that there’s no gearbox.” When we pointed out most small wind turbines don’t have a gearbox, he said, “If you want to bring turbines closer to where we live and work, they’re going to have to be a lot more agile and durable, and take the volatility out of the wind. It’s in our interest to get small wind successful for everybody, not just for us.”

Perhaps not surprisingly, some in the small wind industry are critical of the WindTronics concept.

Green-trust.org wrote, “I keep telling folks that the new ‘Honeywell’ wind turbine is a case of marketing trumping science.” Dan Fink told us, “The claims on the WindTronics website defy the laws of physics, exceed the Betz limit, and overstate the amount of power that’s in the wind. I can’t believe Honeywell lent their name to something like that.” Rejecting their claim of “reducing resistance and friction,” Fink said energy “boils down to size of collector and speed of the wind.”

Fink added, “Honeywell is a high solidity rotor, so there’s no way they could get a coefficient of performance of even 30 percent, which is what most small wind turbines do, like the ones we build and the models from Southwest Windpower.”

Ian Woofenden told us, “I’m flabbergasted Honeywell would put their name on a product like that. It’s very unfortunate. It’s more of the same, marketed as rooftop. It’s another black eye for the industry. It marginalizes real machines. No one buys wind turbines to see something that spins. They want renewable kWh and cheaper kWh, and a rooftop turbine will not deliver either of those things.”

Paul Gipe wrote an essay that’s highly critical of the WindTronics. Among other issues, he pointed out that the WT6500 has a diameter of only 6 feet (1.8 m), or a swept area of 2.6 m². “Using the standard power rating, a turbine of this size should be rated at 500 W”—although the company lists it at 2.8 kW. Gipe also stressed that most small wind turbines don’t have a gearbox, and wrote, “Mechanical resistance is not a significant factor in wind energy generation.”

We asked Levine to respond to these experts. “Not one of those individuals has ever picked up the phone and called us or come to our labs. This is not a company cloaked in secrecy,” Levine told us. “I’ve never seen an industry more resistant.” Levin added, “I bet in a year we can double the output, but I need to go to market now, and be honest with people.”

Levin said he did not know “where we rate on the Betz scale.” He offered to put us in touch with the inventor, but repeated attempts to follow up were unsuccessful. Levin added, “You can’t only look at swept area, because when you move the magnets and stator to the perimeter you create a different generator. Rather than turning a generator with a wind turbine, we built a generator. There is no traditional gear-or generator-based turbine that is as efficient in class 4 winds.”

We asked Levin the most important question: How much energy are people actually seeing with the turbine in the real world? His answer: “We’re not old enough to do that yet.”

Levine added, “Our goal is to drive cost per kWh down to the lowest in the world. There’s no company less interested in putting product in the wrong place.” Levine went on to explain that although his company is known for targeting rooftops, he hopes the majority of buyers will use “poles” instead, on “open spaces.”

“We all subscribe to the exact same laws, but by changing friction and resistance, getting noise and vibration out, and getting size to a proper level we’re producing a mainstream product. This is the most flexible, lightest, quietest, least vibration-prone turbine, with the least constraints.”

Power Up! Our conclusion: Prove it. We wouldn’t think of buying a Honeywell turbine (Figure 12-14) until we see a few years of hard performance energy data, preferably from multiple sites at different wind speeds. Whether the company’s stated design advantages pan out remains to be seen. We think the burden of proof is on them.

Advantages of the Honeywell/WindTronics Turbine

• Looks novel

• Relatively inexpensive ($5,995, plus $3,000 installation)

• Quiet

• Five-year warranty

Disadvantages of the Honeywell/WindTronics Turbine

• Unproven technology

• Unlikely to produce much power on rooftops

• No available real-world data

• No long-term track record

Optimizing Existing Designs

Now that we’ve had some fun looking at kites, blimps, and pocket-sized turbines, let’s take a look at some of the advancements being developed for more conventional equipment. Many inventors claim to have made improvements on the standard HAWT, but not so many examples have caught on.

Here we take a look at some of the more promising areas of research.

Ducted Rotors

Also called diffuser-augmented wind turbines (DAWTs), this concept places the turbine inside a duct that flares out at the back. The idea is to enable the turbine to work in a wider range of winds and to get higher power per unit of rotor area. However, the ducts can also be bulky and heavy, which is a bummer.

Multirotor Turbines

Increasing the number of rotors would increase the total swept area, but it can also lead to turbulence problems that rob you of precious energy, not to mention maintenance headaches. Still, California-based inventor (and former heavy metal rocker) Doug Selsam has been working to overcome the challenges, and has built hundreds of prototypes. He has also sold several dual-rotor, 2 kW systems to homeowners (Figure 12-15).

FIGURE 12-15 Former heavy metal rocker-turned wind turbine designer Doug Selsam has sold a handful of his SuperTwin dual-rotor systems. Selsam Innovations.

Selsam charges $3,000 for the 10-foot diameter SuperTwin and $3,200 for the 12-foot diameter model. In both versions, both rotors combine their power to turn the same alternator.

Selsam worked on some of the fluid dynamics for his multirotor concepts while a student at the University of California Irvine, before he dropped out. He then began building generators and electronics for the wind industry, and eventually landed a grant from the California Energy Commission to support his inventions. He has tested numerous designs, including a “5-star superturbine” and a 7-rotor model (Figure 12-16). Selsam claims the rotors are carefully spaced and offset so that each one receives fresh wind, avoiding the wake of the previous. He says they all drive the same shaft, reducing the potential number of moving parts, and that their small size helps them easily achieve high RPMs.

FIGURE 12-16 Selsam says his multirotor creations offer more swept area for less blade material, plus higher RPMs. Selsam Innovations.

Selsam captured a lot of press with his prototype 25-rotor turbine, which he says produces three kilowatts. One end of this “Sky Serpent” is tethered to a small tower while balloons hold the other aloft. With the blades spinning, the whole thing looks like a giant party streamer or prayer flag.

Over email, Selsam told us that the Sky Serpent was constructed specifically at the request of Popular Science Magazine and that it won “Popular Science Invention of the Year 2008” and was the centerfold of the June 2008 Issue. He said he was also invited to speak about the project at the U.S. Patent Office.

“The Sky Serpent is the leading candidate for airborne wind energy and was the only working prototype at the first world Airborne Wind Energy Conference at Cal State Chico and Oroville in 2009,” Selsam explained. “This in a field against Boeing, Honeywell, etc.”

Selsam envisions the skies full of long strands of multirotor turbines, with some floating or anchored to the sea floor (Figure 12-17). It’s possible that a string of small turbines would be less likely to inspire NIMBY resistance than fewer large ones.

FIGURE 12-17 Selsam envisions millions of multirotor turbines placed out at sea and lofted into the air. Selsam Innovations.

Selsam says his designs get the same amount of power as a large turbine with less blade material and less weight. “The power multiplication by far outperforms any previous method of power augmentation for a wind turbine,” he told us. “This is a fact and not anyone’s opinion.” Selsam says his seven-rotor Superturbine was independently tested by Windtesting.com and verified to multiply output 6-7 times over a single-rotor turbine using the same blades (Whisper H-40 or Whisper 100 from Southwest Windpower). These promising results were published in a paper prepared for the California Energy Commission, which sponsored the project.

In 2008, Paul Gipe installed one of Selsam’s SuperTwin dual-blade turbines at his test facility. He tried to run a test for a year, noting, “The unit is more powerful than turbines I’ve tested before and this has required several time consuming and expensive modifications of our test equipment. These upgrades were never fully completed. Because of other commitments, testing the turbine has not been a priority. Consequently, the tests remain incomplete.”

Gipe concluded, “The Super Twin is experimental, but it is an option for someone who likes to tinker with their wind turbines.”

Over email, Selsam told us, “Paul also tested a Bergey of the same eight-foot diameter, but mine was more powerful, again proving beyond a shadow of a doubt that the extra rotor makes more power. Additionally, the Bergey uses the best NREL airfoils, whereas my SuperTwin used 2×4’s shaped on a belt sander, and still outperformed the Bergey.”

Selsam argued, “The dirty secret of all this clean energy stuff is that despite millions and millions in funding, the big labs categorically refuse to build or test anything truly new. They’d rather waste millions on a few select dubious ideas that passed through the gauntlet of bureaucrats than adopt a broader, high-throughput approach to research that could identify and leapfrog promising new technologies by building and testing many new ideas.”

Selsam did concede that some of that resistance to “new designs” is well founded. “Most ‘new’ designs are not new at all and most are over 1,000 years old,” he told us. “They almost invariably repeat past mistakes. Imagine an airplane sporting a riverboat paddle wheel for propulsion, and you can see how ridiculous most ‘alternative’ wind turbines seem to those of us with 101+ burnt-out turbines under our belts.” Still, he said, “But even a whole bushel of rotten apples can have one good apple in there somewhere!”

Selsam told us that rather than try to reinvent the wheel, his designs build on the time-tested “propeller” shape, but sweep more area with less material. “Imagine if the flashlight industry had never discovered stacking multiple batteries.” Selsam said. “Imagine if all cars had only single-cylinder engines! Imagine if you had to cover your roof with a single large tile (Fred Flintstone?) Sweeping a huge area with a single large propeller is the Fred Flintstone approach to wind energy.”

Doug Selsam has big ideas for wind power at large and small scales, and he hopes to get more support for his multirotor concepts. Early tests suggest that it’s something that certainly deserves more study. One thing to note is that, as expected, the power curves on Selsam’s website show that his multirotor concepts harvest very little energy out of low winds. There are no designs that cheat nature.

Counter-Rotating Dual Turbines

A typical wind turbine creates a significant amount of tangential or rotational air flow, the energy of which is wasted. However, clever engineers have suggested that this flow could be harvested by a second rotor spinning in the opposite direction.

In fact, a friend of German wind pioneer Albert Betz, Hans Honneff, wrote a book on counter-rotating dual turbines in the 1930s. According to an article in the e-magazine Alternative Energy, Honneff described an array of large turbines, set three to a tower, with each rotor revolving separately from the others. Honneff called for rotor diameters of 150 meters and a massive output of 21 MW. The Nazis gave his idea a whirl, and the Third Reich Wind Energy Ministry tested ten-meter-diameter models.

In the late 1970s, Trimble Windmills produced some small, 5 kW counter-rotating dual turbines, which were sold for farms and isolated heating operations. According to Alternative Energy, these machines had a contra-rotating permanent magnet alternator and sail wing blades attached to each half. They achieved a “respectable Cp (coefficient of performance) of 0.37,” although the magazine suggested that the two sets of blades were actually spaced too close together for optimal results.

In the early 2000s, Kari Appa tested counter-rotating turbines with funding from the California Energy Commission. Appa reported extracting 30 to 40 percent more power out of the winds versus a comparable single-rotor system.

So why aren’t more turbines dual-action? For one thing, they would cost more up front, although some supporters have argued that they are likely to be less expensive than choosing a larger single-rotor system. However, dual turbines are significantly more complicated machines. Although they can help minimize gyroscopic forces on equipment, dual-rotor systems must be configured just so, or they can quickly run into trouble. With more moving parts comes greater chance of failure and increased maintenance time and expense.

Still, if dual turbines can be developed that are easy to install and maintain, and that show consistently higher energy returns, they may become economically advantageous in the near future.

We may one day look back with amusement on the quaint old days of single rotors.

Telescopic Blades

Some designers have proposed making turbine blades telescopic so they can extend their swept area when winds are optimal, but retract during high winds to avoid damage. They would also be easier to ship and store.

However, making blades telescopic is also likely to make them less strong. If one of the blades gets stuck, it could be a real hassle to loosen it, especially if you don’t have a climbable or tilt-up tower.

Telescopic blades could also increase the price of the rotor in a way that could take a long time to pay off financially.

Laser-Guided Turbines

Danish researchers have recently been experimenting with laser-guided active controls for utility-scale wind turbines. The idea is to pair a laser with an anemometer to actively measure the winds.

Torben Mikkelsen, a professor at Denmark’s Risø DTU, told Science Daily, “The results show that this system can predict wind direction, gusts of wind, and turbulence. So we estimate that future wind turbines can increase energy production while reducing extreme loads by using this laser system, which we call wind LIDAR.”

So far, tests suggest lasers can boost energy production of wind turbines by around 5 percent. Although the expense and relatively low payoff is bound to keep such technology out of the hands of small wind farmers for years, it is conceivable that lasers could one day trickle down. Of course, most small wind turbines don’t currently use computer-assisted active controls, but that could change as technology improves and gets cheaper.

You may one day be able to boast to your neighbor about your turbine’s “frickin laser.”

Advanced Active Controls

As stated previously, most small wind turbines don’t have active controls, as utility-scale machines do. However, that might not always be the case. Active controls, in general, keep blades positioned to maximize energy harvested at every moment. They allow turbines to extract more energy at higher wind speeds, and help prevent damage during storm events.

A number of researchers are working on improving active controls through advanced software programming, algorithmic modeling, and improving sensory outputs, through the use of lasers and other devices. Some researchers are looking at ways to improve the evenness and “quality” of power generated to make it less spiky according to changes in the wind. One idea is to keep some of the energy from a strong gust in the form of kinetic energy—in the form of fast spinning blades—instead of converting as much as possible directly to electricity. Then, when the wind dies down a moment later, the blades will still be spinning fast, and the electricity can be produced at that point. The overall effect could be more even power production.

Other analysis seeks to better optimize the amount of power harvested at each wind speed by actively adjusting blade rotation speed as needed.

Given high costs of implementation and the relatively small size of most home systems, we don’t expect to see that many active controls on the market very soon. But they could become standard one day. True, some active controls are already available on Quietrevolution VAWTs (Chapter 8), though those machines tend to run a bit expensive.

Summary

We hope this book has been a useful introduction to the exciting world of small wind power (Figure 12-18). As we have shown, the industry is far from mature, and it faces a number of challenges, including relatively high cost of entry, a scarcity of qualified technicians and installers, and fairly demanding maintenance schedules. Oh, and you need a great wind resource, or you’re paying a lot of money for a fancy lawn ornament.

FIGURE 12-18 This Bergey Excel 10 kW turbine still serves as a teaching tool at the Liberty Science Center in New Jersey, which has gorgeous views of Manhattan. An early plan for the new World Trade Center included building-integrated wind turbines, but that idea was scrapped. AWS Scientific, Inc./DOE/NREL.

In this chapter, we presented a brief survey of cutting-edge wind technology, some of which may result in outstanding products in the near future. As we’ve mentioned, there tends to be a great deal of hype around novel designs. The mainstream media tends to breathlessly report on every press release from a rising number of secretive startups, which often claim to have invented “revolutionary” small wind turbines that can fit neatly on your roof, power a small village, and even start working in the faintest breeze. By the way folks, it is totally bird-and bat-friendly and can make you a nice hot cappuccino.

By now, you should be armed with the tools to evaluate initial claims of any wind power purveyor. You will ask to see real-world energy data, preferably from independent sources, and you will go to great pains to verify the quality of your wind resource, not to mention the local regulatory environment. You’ll know to run away from anything that claims to be a “Betz beater,” and you’ll insist on finding out the real coefficient of performance.

Of course, if you are an engineer or a hobby tinkerer, you may read this book and decide that you are ready to try out your design for an eight-rotor, kite-lofted piezoelectric power plant. If so, more power to you. Just stay safe, and let us know how she turns out. Don’t forget to send a picture.

For his part, Paul Gipe told us, “If you want a windmill as a statement, to be green, I’m fine with that. You want it as a recreational thing that also produces electricity, that’s better than a Jacuzzi, snowmobile, or wine bar, it will do something useful. But I’m talking about putting up a wind turbine to make a profit. The only way we’re going to get enough windmills to save our butts is that they have to be profitable.”

Dan Fink told us, “The general public understands solar panels pretty well, but the wind resource is totally confusing to people. If someone gave you a solar panel the size of a playing card, and said you could stick it on your roof and power an electric car, no one would believe you. Or if they said a one-ton pickup could get 50 mpg, no one would believe you. But people don’t understand wind energy.”

Fink added, “The small wind industry has a high proportion of dissatisfied customers, because people have unrealistic expectations.”

Ian Woofenden told us, “If you misunderstand how much energy is in a gallon of gas, who cares about your car design? If you don’t know your wind resource, you’re sunk.”

When we asked Hugh Piggott to look at the big picture, he said, “Most people have assumptions that they can put something on their roof that will generate most of their electricity in an urban environment. That’s a really, really long way from the truth.”

We hope this book has brought you closer to understanding wind energy.

Morten Albaek, senior vice president for global marketing of Vestas, told us he sees “a fairly bright future for microturbines.” The Dane added, “They’re tangible to consumers, just like solar panels on rooftops. We think most wind energy will [continue] to be developed by classic large wind farms, but we think the next developments in wind energy technology will be in micro-turbines. The amount of energy we will be able to get from micro-turbines is going to be limited, but important, compared to what we will get from large classical wind turbines, but I really hope the micro-turbine industry sees success.”

Albaek added, “The stupidest thing we can do is put a turbine, large or small, in a place that has no wind. It’s also stupid to drill in Saudi Arabia when we have such great wind here.”

May the wind always be at your blades!