Cleantech Market Intelligence
Building a Better (and Bigger) Wind Turbine
In early 2014, MHI Vestas, a joint venture between Vestas and Mitsubishi Heavy Industries, announced its new V164-8.0 wind turbine. Designed for offshore use, the massive wind turbine is currently the largest in production and already has secured orders at multiple offshore wind farm projects including the Burbo Bank Extension, the Walney Extension, and the 448 MW Borkum Riffgrund II project in Germany. At 80 meters long, the blade is the largest in the industry, not counting the 83.5 meter blades used in the Samsung S7.01-171 turbine currently in limbo. A team of researchers has been given a grant by the Department of Energy’s Advanced Research Projects Agency-Energy program to develop a 50 MW wind turbine that would require a blade at least 200 meters long. The idea is that a single machine capable of producing the same amount power normally generated by 10 to 20 machines will reduce overall construction and maintenance costs.
Researchers from several different institutions will collaborate to design this massive turbine. Led by the University of Virginia, the project will also include engineers from Sandia National Laboratories, the University of Illinois, the University of Colorado, the Colorado School of Mines, and the National Renewable Energy Laboratory. Corporate advisors will include Dominion Resources, General Electric (GE), Siemens, and Vestas. The project will be a continuation of the work Sandia has completed on a 100-meter blade (328 meters in diameter) that would go into a 13 MW wind turbine. Doubling the length of a turbine blade is no small task. Segmenting the blades can help solve the construction and transportation issues; however, the massive weight and associated blade fatigue, peak stresses, and cost are major limiting factors.
Cutting the Weight
Sandia has experimented with several different technologies in an attempt to reduce the weight of the blades. The addition of a carbon spar cap, new core materials such as balsa, and flatback airfoils have all been examined. The company accomplished a weight reduction of over 50% from its original 100-meter blade design, which weighed in at 114 tons. Studies and testing have continued in order to quantify potential issues such as tip deflection, panel buckling, flutter speed, and aerodynamic design load.
Palm Trees for Turbine Inspiration
(Source: Popular Science)
These blades will utilize a design called the segmented ultralight morphing rotor. They will be built and assembled in segments to avoid the difficult logistics of transporting blades built as a single unit. Because of the blades’ adaptability to windflow, they will have less structural mass (i.e., ultralight). Unlike conventional turbines that are configured upwind of the rotor, these turbines would be placed downwind. This feature, combined with the segmented nature of the blade, allows them to bend forward in order to reduce stress in strong windstorms such as hurricanes. This feature was inspired by the way palm trees move in wind storms. When speeds are within the optimal power-producing range, the blades will spread out in order to maximize energy generation.
Chances are slim to none that this technology makes it into the marketplace anytime soon, if at all. However, people today are surrounded by once seemingly impossible technology deployments from the nano to macro scale. At the very least, research projects like this are showing that when it comes to advancements in wind turbine technology, turbine vendors and researchers alike are not afraid to think big.