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Judith Gap wind turbines go online(Billings Gazette (MT) (KRT) Via Thomson Dialog NewsEdge) Jan. 8--When Billings residents plugged in their Christmas lights this year, there's a chance the glow was compliments of a steady breeze through Judith Gap. In late November, the first of Invenergy's turbines at the Judith Gap Wind Energy Center started fueling the grid with wind power. As of this week, 50 more turbines have come online and by the end of January, the company hopes to have all 90 up and running. Now the flurry of crews that dug trenches, poured concrete and "flew" rotors to the tower tops earlier this year has been replaced with reclaimed roadsides, a handful of technicians and 90 giant turbines visible from more than 25 miles away. John Bacon, onsite manager for Invenergy, the Chicago-based company that owns the wind farm, checked his computer Thursday morning to determine how much energy the wind farm was producing. The wind, gusting furiously only 50 miles away in Big Timber, was barely breezing through the gap at 10 mph -- well below the optimal 20 mph. "This should be producing 76 megawatts," he said, "but we're only producing 24." Every morning, Bacon calls NorthWestern Energy, which purchases the wind power for its customers, to report how much energy he expects to send online. "NorthWestern determines which way they're pushing power, either toward Great Falls or Billings," said Troy Ryan, the site lead for General Electric, the company that supplied the 1.5 megawatt wind turbines for the project. The Judith Gap project straddles Northwestern's 270-kilovolt transmission line that runs between the two cities. "They look at Billings or Great Falls as sinks. However many people are turning the lights on, it (electricity) will gravitate toward that." To make the best forecast for NorthWestern, Bacon frequently checks into the National Oceanic and Atmospheric Administration Web site. But, he said, NorthWestern plans to add three strategically placed meteorological towers to improve his predictions. In an office next to Bacon's, Ryan makes two daily phone calls. Every morning when he comes on shift and every night when he leaves, he dials up a GE office in Tehachapi, Calif. Via computer, staff in California monitor the Judith Gap Wind Energy Center 24 hours a day, every day. When Ryan comes in, he calls for an update of the previous night's activity and he lets his California contacts know he's back on site. At the end of the day, he calls to "turn the controls" back over to his California counterparts. The "nuts and bolts" of the Judith Gap wind farm involve literally thousands of interconnections and operations. But the complex system, linked via a network of fiber optics, funnels into a computer program that shows up on a computer monitor in California and another in the Judith Gap operations center. "You can do the bulk of your troubleshooting from here," Ryan said, noting that staff in California can even reset some faults that occur in Montana. "The only difference from being up in the turbine are the sights, sounds and smells." And the smells vary, depending on what went wrong, he said. When the "crowbar" fires -- that's the term given to an internal device that protects the generator -- it smells like a firecracker, he said, smiling. This week, a handful of technicians were busy climbing towers to reset faults detected by the monitoring system. "It's still pretty new technology," he said. Once all the bugs have been worked out, probably by late January, the entire park will be run through a reliability test. After that, it's pretty much just maintenance, cleaning and an occasional repair, Ryan said. When asked to explain how wind translates to electricity, Ryan puts it succinctly. "It hits the ground at the substation. It's sold to the utility and it goes to the homes," he said. The technology involved in a large-scale wind farm is complex, but Ryan's assessment is not far off when it comes to the basic principles of wind power. To begin with, wind power is actually a spinoff of solar power. The heating and cooling that take place when sunlight strikes the earth's surface stir up air currents that breed wind. As soon as the wind surges through the rotor of a wind turbine, the kinetic energy takes a path that involves a number of "steps up" and "steps down" before it can illuminate Christmas lights in your home. As the wind through Judith Gap turns the rotor on a wind turbine, it spins the blade at 20 revolutions per minute. A gear box inside the turbine bumps that up 76 times, so that by the time it hits the generator, the revolutions per minute have reached 1,440, the rotational speed required for the generator to convert the mechanical power into electricity. The 600 volts coming off each turbine is fed through a cable to the base of the tower, where a transformer steps up the voltage to 34.5 kilovolts. From there, the electricity travels to the on-site substation along a system of buried cables. A large transformer at the substation steps up the power again, this time to 230 kilovolts -- the same voltage that's passing through NorthWestern's transmission lines. "If you think of the substation as a giant electrical outlet, the wind farm will plug into the substation at the site," said Claudia Rapkoch, spokeswoman for NorthWestern Energy. "Connecting to our substation is access to our transmission lines. Once it's come into the system, it can go anywhere on our transmission system." She likens the grid to a network of streets. Electricity will travel along the high-voltage transmission lines -- the virtual "highways" of electricity transportation -- as it traverses the state. Transformers in substations along the way "step down" the high-voltage power to lower-voltage distribution lines that serve Montana's communities. The power may be "stepped down" several times again before it arrives at a home or office building, where the consumer uses 110 volts to power lights and electric toothbrushes -- or even a fan to create wind. Unlike some resources, electricity cannot be stored. So the challenge of providing power is being able to meet the demand at any given time. "Energy pulsing through the lines always has to remain balanced," Rapkoch said. "What goes on a system always has to be equal to what comes off." The unpredictability of wind requires energy suppliers to coordinate backup supplies. For that reason, "free" wind isn't exactly free. Besides the cost of developing the wind farm -- Bacon says, as a "turnkey deal," the wind energy sells at about $1,000 per kilowatt, about the same as other resources -- the cost of wind power is blended with the cost of backup energy. To get the best price for consumers, energy suppliers consider the reliability and cost of a resource, along with the benefits of diversifying their energy portfolio, Rapkoch said. Consumer demand also played into NorthWestern's decision to invest in wind power. "It's difficult to say with a degree of certainty whether it (wind) will lower or increase the costs," Rapkoch said, but added that NorthWestern's aim is to find the right balance of reliable energy at the lowest cost possible. Until the Judith Gap Wind Energy Center came online, small wind farms and individual turbines dotting the Montana landscape have produced only about 1 megawatt of power. But when all 90 turbines at the gap are spinning to capacity, they will produce 135 times that amount. Each turbine alone will provide enough energy for approximately 350 to 400 homes -- or essentially 8 percent of NorthWestern's supply. But the 135-megawatt wind farm is dwarfed by Colstrip's coal-fired plants, which produce 2,200 megawatts at full capacity. And the demand for electricity continues to grow. Rapkoch said NorthWestern projects a 1.5 percent increase annually. The contract between Invenergy and NorthWestern, which locked in 20 years' worth of wind, has been permitted for up to 188 megawatts, which leaves the door open for Invenergy to expand the project by another 30 turbines. Whether or not that will happen, Bacon said he expects to know by spring. Beyond that, NorthWestern Energy has no immediate plans to include more of Montana's wind in its energy portfolio. "This is what we feel is the right amount for the time being," Rapkoch said. "From a default supply standpoint, there's nothing immediately on the horizon." |