COMPOSITESWORLD.COM is the #1 website for composites materials and services. COMPOSITESWORLD.COM receives over 40,000 unique visitors a month and is projecting over 3 million page views in 2006. High Performance Composites, Composites Technology and
Issue link: https://ct.epubxp.com/i/178128
feature: Wind energy update Siemens AG (Erlangen, Germany) is building what is purported to be the world's largest wind turbine, the SWT-6.0-154. Each of its three B75 blades measures about 75m/246 f in length. Fabricated as a single cast part, comprising glass, epoxy and balsa wood, the blade is molded via the company's patented and trademarked IntegralBlade process. Te seamless blade has no bonded joints — weak points that could crack or separate, exposing the joint to water ingress and accelerated weathering. Additionally, a weight savings of about 20 percent, compared to conventionally produced blades, is achieved by incorporating a specially designed blade profle, shaped to maximize the rotor capacity factor at a variety of wind speeds. Te turbine has a cut-in wind speed of 3 to 5 m/sec, produces nominal power at 12 to 24 m/sec and has a cut-out wind speed of 25 m/sec. It is part of the company's D6 platform, which replaces the gearbox, coupling and generator with direct-drive technology that eliminates about 50 percent of wear-prone and geared parts. Te reduction in associated maintenance costs is especially advantageous for ofshore applications. Siemens is testing the B75 blades on a prototype 6-MW turbine at Denmark's Osterlid test station. Afer testing is complete, power supplier Dong Energy (Fredericia, Denmark) plans to pur- chase and install about 300 SWT-6.0-154 turbines of the British coast, according to a recent press release from Siemens. Meanwhile, Kolding, Denmark-based LM Wind Power's 73.5m/240-f blades were installed on Alstom's (Levallois-Perret, France) Haliade 150-6MW wind turbine in Carnet, France, this past year, and the company has plans to open a blade manufacturing plant in Cherbourg, France, and begin production of the blades there by 2016 (see "Learn More," p. 35). Te glass/polyester blades feature the company's SuperRoot design, which supports blades that are up to 20 percent longer without an increase in root diameter. Additionally, in 2012, LM Wind Power extended its GloBlade line of ultraslim wind turbine blades to 3-MW turbines. Originally introduced for the 1.5-MW segment, the GloBlade replacement blades are designed with "plug-and-play" features that make them compatible with a variety of turbine platforms and aerodynamic confgurations. Te new 3-MW line includes 58.7m and 61.2m (192.6-f and 200.8-f) blades, which the company says can improve annual energy production by as much as 14 percent, compared to the standard blades they replace. Molded Fiber Glass Cos. (MFG, Ashtabula, Ohio) custom molds blades and a variety of parts for wind turbines. For example, the Source | GE Global Research A different type of blAde? A potential paradigm shift in wind turbine blade manufacture is afoot at GE Wind Energy (Niskayuna, N.Y.). The companyÕs global research arm, along with Virginia Polytechnic Institute & State University (Blacksburg, Va.) and the National Renewable Energy Laboratory (Golden, Colo.), recently secured a three-year grant under the U.S. Department of EnergyÕs Advanced Research Projects Agency to investigate the use of resin- impregnated architectural fabrics as a substitute for conventional composite laminates in the construction of wind blade skins. In this design, as envisioned, fabric is stretched or ÒtensionedÓ around a spaceframe of stamped metal ribs. The fabric is impregnated with resin to make it impermeable to wind and water intrusion. Wendy Lin, GEÕs principal engineer and lead on the project, declines to identify the fabric; however, she stresses that the resin is nei- compositesworld.com ther an epoxy nor a polyester, but 32 a Òrubbery,Ó compliant material Wendy Lin, a principal engineer at GE Global Research, wraps resinimpregnated fabric around a prototype wind blade segment. The inspiration for GE's tensioned-fabric concept was a similar fabric used as the cover of an outdoor café (left) at GE's John F. Welch Technology Center in Bangalore, India. that allows GE to assemble the blade in large segments without risk of the blade buckling. Lin says the impetus for the project was an internal directive at GE and eliminate the logistical problem, and associated costs, of transporting long blades to turbine sites. Instead, the blade components could be to reduce the cost of manufacturing wind blades by 50 percent. If the shipped in container kits and assembled on site. ÒWe still have a ways fabric is successful, GE claims the new blade design could reduce blade to go to prove it out, however,Ó Lin admits. ÒSize constraints imposed by production costs by up to 40 percent and put wind energy on equal current technology require thinking outside the box.Ó But, she says, the economic footing with fossil fuels, without government subsidies. Lin concept could pave the way for blades as long as 130m/426.5 ft, mak- says the design would permit automotive-type precision and tolerances ing them suitable for harvesting wind in moderate wind locales.