A New Crop Takes Root
Windmill farms are proliferating in Pennsylvania and other mid-Atlantic states, as modern wind turbines generate clean energy . . . and profits too.
By Tom Gibson
Driving through the countryside, up and down hills and past bucolic farm land replete with split rail fences, we come to the top of Laurel Ridge above Cranberry Lake. Rain had fallen that morning, and a foggy mist shrouds the mountain. We soon realize something else is combining with this to create an eerie scene: a series of huge windmills towering like statues along the ridge as cows graze below them.
A steady wind blows, and the windmill blades rotate slowly with a steady hum and slight squeak. While we wait, cars stop, and people get out and gawk at the huge airplane-like propellers. Mimi Abel, a summer engineering intern with Zilkha Renewable Energy, drives up. Then comes Gary Verkleeren, project manager at Zilkha. "Boy those things are cooking," he observes as he looks up at the windmills.
This is the Mill Run Wind Project, recently built near the town of Mill Run in southwestern Pennsylvania. Wind farms like this have started popping up in greater numbers in the Mid-Atlantic, especially in Pennsylvania. In years past, western and Great Plains states garnered the lion's share of wind farms, but today, states east of the Mississippi account for the majority of new wind projects. Brent Alderfer, an electrical engineer and president of Community Energy, a partner in mid-Atlantic wind ventures, says, "In 1999, Pennsylvania and the Mid-Atlantic had no wind energy at all, and we now have more than 100 megawatts coming online." That's enough to power 38,000 homes.
The Mill Run wind farm and a sister one nearby in Somerset represent the new breed of wind farms built as legitimate money-making operations, not just for environmental reasons. Theodore de Wolff, an engineer and owner of Atlantic Renewable Energy in Richmond, Virginia, reports, "Within three months, the output of the Pennsylvania projects was sold out to universities and private companies. So commercially, it has been successful."
Between 1981 and 2000, windmills improved in power output by 125 times while increasing only 20 times in cost. As Alderfer says, "That's the story of the rapid worldwide expansion, particularly in more moderate wind regimes like Pennsylvania and the Mid-Atlantic, New York, and New England. It's basically taller towers and longer blades, so a bigger rotor comes on at much lower wind speeds. Rotors have diameters of over 200 feet and very thin blades, so they can come on and generate power in as low as 8 miles an hour of wind. That kind of technology really brings down the price because you can harness that much more of the wind."
Meanwhile, machines have become friendlier to their surroundings, as well, in response to early-generation models that annoyed neighbors and killed large numbers of birds. Towers consist of tubular steel with fewer perches for birds, and slower-rotating rotors kill fewer of them. Tubular towers, usually painted off-white or gray to blend with the sky, also prove quieter than the lattice structures previously used. Verkleeren, project manager for the Mill Run and Somerset sites, notes, "One thing that surprised me most is how quiet they are."
So why build wind farms in Pennsylvania and surrounding states? Alderfer, explains, "The simple answer is, that's where the people are. The challenge is how to bring renewable energy on line where we use the most energy, which is the Northeast. The Mid-Atlantic is where I grew up, so I have an interest in the environment here as well. Pennsylvania is ground zero for acid rain, as it has some of the highest acidity levels in natural rainfall thanks to coal plants in Pennsylvania and to the west. So it's a good place to start."
More than most states, Pennsylvania has shifted to a deregulated power market, and many consumers are choosing to support renewable energy. Alderfer says, "It's all based on customer demand. We grow only when we find customers who will support wind energy, and the more sign up, the more turbines we put up. That's our simple formula."
The most productive wind energy regions generally fall in mountain or coastal terrains, with the northern portion of the Appalachian chain -- southwestern Pennsylvania, western Maryland, and the West Virginia panhandle -- among the areas with the highest potential. The mountain ridges of Pennsylvania, also including the Poconos in the eastern part of the state, offer some of the best wind resources in the East.
As Theodore de Wolff, says, "Of course wind power has disadvantages. We can provide power only when the wind is blowing. Therefore, wind power can only be combined with power from fossil resources -- coal and gas plants -- or other renewable energy forms." To get around the problem of wind variability, wind mill output feeds to the main electrical power grid spread throughout the country. Sophisticated power electronics make the output of turbines at Mill Run and other projects suitable for grid interconnection and distribution.
A Complex Effort
As we stroll up the access road to the first windmill, Verkleeren explains how he's a civil engineer by training who went to Penn State. Before this job came along, the Pittsburgh native worked at consulting firms doing geotechnical work and foundation design. He was living 15 or 20 minutes away when he heard about the Mill Run and Somerset projects coming to the area. Seeing a unique opportunity, he contacted Zilkha and Atlantic about working for them. "I told them I'm the ideal person you need for this job." He started out consulting for them, arranging local permits, and then they hired him fulltime a year before construction began. After he managed construction, "They thought I could pick up the operational aspects and then run it, and it's worked out that way. You can learn anything if you're really interested in it," Verkleeren recalls. "I always had an interest in renewable energy, going off grid and all that."
Because of the tremendous upfront costs associated with huge windmills, projects only become feasible after a customer such as a large utility makes a long-term commitment to purchase the energy output. Exelon Powerteam made a 20-year agreement to buy the power produced by the Mill Run and Somerset projects wholesale. Exelon Corporation, Powerteam's parent, ranks as one of the nation's largest electric utilities and the largest nuclear power plant operator.
Based in Wayne, Pennsylvania, Community Energy Inc. (CEI) markets clean energy, and under its New Wind Energy brand, it partners with existing electric suppliers such as Exelon to make wind-generated electricity available to commercial and residential customers. In this case, CEI brought in pioneering customers including several colleges such as the University of Pennsylvania, Carnegie Mellon University, and Penn State as well as Philadelphia Suburban Water Company and grocer Giant Eagle.
Having grown up in Montgomery County, Pennsylvania, Alderfer founded Community Energy with a partner in 1999. This came after he got an electrical engineering degree and then went to law school and practiced law for more than 16 years. "Towards the end of that practice, I got more interested in my engineering roots," he reveals. "For me, making a difference in the environment in an engineering field I like took me right to the new renewable energy technologies like wind. It was coming home for me." As a lawyer, he represented small to medium-sized companies in litigation and finance transactions and worked with startups putting entrepreneurial ventures together, so now he finds himself combining his backgrounds.
Walking further up the hill toward its crest, Verkleeren remarks, "It's always windy up here. At the top of this hill, we'll be at 3000 feet." Coming to another windmill, he opens a hatch at the base of its tower, and we walk inside as if venturing into a submarine, only one standing on end. "It's 23 stories straight up," he tells me as we stare up the tube that forms the tower.
Having overseen construction at Mill Run and Somerset, Verkleeren has become an authority on the work involved at a windmill construction site. It initially meant building gravel roads to accommodate trucks carrying up to 190,000 pounds, counting the monstrous windmill nacelles (the generator unit at the top with the blades). Much of the engineering comes from the turbine manufacturer, who sends engineers to the site. Construction firms are of the type that build highrise buildings or roads for state transportation departments. The construction phase usually takes six months to a year.
The most complex phase of construction comes with building the concrete foundation for each turbine. Usually 30 to 40 feet in diameter, these use standard concrete construction, but sometimes with a twist. When bedrock lies in the earth below, the foundation can extend 30 or 40 deep and anchor on it. The Somerset project was built on reclaimed mining land with soft overfill, so they used a much broader foundation that floats on the softer soil. Verkleeren says each foundation has 180 to 200 yards of concrete and 50,000 pounds of steel reinforcing bar in it.
Prospects Look Bright
All this should mean more work for engineers like Verkleeren, although the job of windmill engineer and operator isn't always as glamorous as it may seem. "It's very demanding. It's a 24/7 job," Verkleeren says. He has to cover both sites, Mill Run and Somerset, about 20 miles apart. "You're on the road all the time." And he deals with a host of issues that arise between the multitude of partners involved in playing a new game in the utility arena. But he says, "It's still fun. I like doing my job every day."
Fortunately for Verkleeren, he has the help of Mimi Abel for the summer. Having just graduated from Penn State with a B.S. in electrical engineering, she relates, "I was looking for something interesting for the summer. I found it." Her main job consists of studying computer programs used with the windmills and the data coming from them to put it in a better format for usability and daily logging.
As we wrap up the tour and head back down the ridge, Abel reveals she plans to go to UCLA to graduate school in the fall to study atmospheric science, specifically changes taking place in the atmosphere. Verkleeren sees this as fitting because scientists link changes in the atmosphere to fossil fuel power plants common in Pennsylvania and midwestern states, and here companies are generating energy that should result in a cleaner atmosphere. All the while, the farmer's cows can exist side-by-side with the monolithic but quiet windmills, and local citizens can marvel at them.
Let's Get Technical: Details on the Mill Run and Somerset Wind Projects
The Mill Run project in southwestern Pennsylvania uses ten GE Wind Energy turbine generators, while the Somerset project uses six. Each turbine costs $1.5 million and is rated at 1.5 megawatts at 25-mph wind speed.
Each windmill has a tower height of 210 feet and rotor diameter of 231 feet, making them some of the largest commercial wind turbines in the country. The blades consist of fiberglass with a steel frame.
The rotors use blade pitch regulation and variable-speed operation to allow the turbines to generate more power at higher winds, keep the turbine at maximum efficiency, and minimize turbine drivetrain loads. Continually adjusting the blade pitch angle achieves optimal rotational speed and maximum lift-to-drag at every wind speed. It also provides active damping, resulting in less tower oscillation compared to constant-speed turbines.
Being variable speed, the turbines aren't synchronized to the electrical grid, so they have a pulse-width modulated frequency converter that shapes the AC output voltage to match the grid. A transformer at the base of each turbine steps up the voltage for transmission to a substation. All lines from turbines run underground.
Rotor speeds range from 11 to 20 rpm. Turbines have a three-step planetary spur gear box yielding a 72:1 speed ratio, so the generator turns a maximum 1440 rpm.
The nacelle, or unit with rotor and generator, tracks the wind based on information it receives from a computer-based weather station. The computer calculates average wind speed and the length of time it blows in various directions to determine the optimum direction for orienting the windmills. This way, it doesn't continually chase every slight wind change. Windmills shut down at 55 mph.
The turbines use a programmable logic controller for remote control and monitoring.
For more information on Community Energy, visit www.newwindenergy.com