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As wind whistles down the eastern slopes of the Rocky Mountains, it picks up a lot of speed. It’s not unheard of for gusts of up to 100 miles per hour to slam into the rolling green foothills just outside of Boulder, Colorado.
Those conditions, which can be quite harsh sometimes, also make the area the perfect place for evaluating wind turbines. In fact, for the last few years, engineers from the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) in Colorado and GE have been pushing a 3-megawatt turbine to its limits and beyond, validating new blade designs, devising better ways for wind turbines to handle strong gusts of wind and developing software that can make wind turbines more efficient and smarter. The grueling series of assessments, which concluded in May, provided insights for a new generation of GE turbines that have already started popping up in the U.S., Europe and elsewhere in the world. “This turbine went from initial certification to being a test bed for new technology,” says Albert Fisas, an advanced technology manager at GE Renewable Energy.
Research facilities like NREL’s National Wind Technology Center near Boulder are important proving grounds for new technology as wind keeps increasing its share of the energy mix. For example, the U.S. Energy Information Administration says that 2019 could mark the first year when wind generation exceeds hydropower generation in the U.S. The same agency estimates that wind operators will add 54.2 gigawatts in generation capacity between 2018 and 2022.
The 3-megawatt turbine Fisas has helped erect, validate and retire was originally developed by Alstom, the French company whose energy businesses GE acquired in 2015. Back in 2010, the plan was simply to work with NREL to certify the wind turbine for the U.S. market. But after the successful two-year certification process, Fisas’ team and NREL reached an agreement to leave the turbine in place and try new tricks on the machine.
Over the years, the turbine has helped GE develop several innovations that are widely used on wind turbines today. One important research project involves a load damper. This technology helps wind turbines deal with sudden bursts of wind — bursts that can cause vibrations capable of damaging the turbine tower. “When you assess something in the field, you have much more information than if you’re just simulating it on a computer,” Fisas says.
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Top image: NREL’s Pulitzer Prize-winning staff photographer, Dennis Schroeder, won a photo contest by capturing a blade inspection at the 3-megawatt GE wind turbine. Caption and image credits: Dennis Schroeder/NREL. Above: Two cranes support the removal of a blade on the GE turbine. Image credit: Lee Jay Fingersh/NREL.
The dampers work like shock absorbers on a car. Three large metal supports are bolted to the concrete foundation and then attached to the turbine tower about one-third of the way up from the ground. As wind loads bear down from wind hitting the turning blades, the dampers absorb the induced forces and keep the tower stable. At NREL, GE engineers were able to confirm that the dampers cut down on vibrations. Such technology could prove important as engineers develop larger offshore wind turbines, such as the Haliade X, a 12 MW offshore wind turbine with a rotor diameter measuring 220 meters, which will be the largest in the world. Dampers for large offshore turbines will protect the turbines not just from wind, but also from loads induced by tide and waves.
Another innovation to come from the NREL site: using a Lidar system. Lidar, short for “light detection and ranging,” records distance by bouncing lasers off a target and measuring the reflected pulses. It can read wind speeds up to 30 second before it hits, then feed the data to software that automatically adjusts the turbine to absorb the blow. “It was a very powerful moment when the outcomes of evaluations in the field matched performances of simulations in a computer,” Fisas says. “Now we can take all of this learning and apply it to new products.”
Last month, GE ended the 3-megawatt turbine’s eight-year research effort with NREL. Engineers used giant cranes to reverse the process they had gone through in 2010 when they installed the turbine. First, they removed the blades one by one. Then they took down the nacelle, which houses the turbine’s generator and other technology. And finally they carted away the tower in five sections. The blades will be shipped to Mexico, where they will spin new generators. The nacelle may be shipped to a GE wind energy learning center, where the company can use it to train future wind turbine operators.
Fisas, who originally hails from Barcelona, now lives in Schenectady, New York, and focuses on offshore wind turbines. Still, the decommissioning was a bittersweet affair. “I’m happy I got to be a part of it,” Fisas says. “On the day we were taking down the last tower part, I was hosting seven NREL scientists and engineers in Schenectady. This is a collaboration that I know will continue.”