Materials and Innovations for Large Blade Structures: Research Opportunities in WInd Energy Technology

Abstract

The significant growth in wind turbine installations in the past few years has fueled new scenarios that envision even larger expansion of U.S. wind electricity generation from the current 1.5% to 20% by 2030. Such goals are achievable and would reduce carbon dioxide emissions and energy dependency on foreign sources. In conjunction with such growth are the enhanced opportunities for manufacturers, developers, and researchers to participate in this renewable energy sector. Ongoing research activities at the National Renewable Energy Laboratory and Sandia National Laboratories will continue to contribute to these opportunities. This paper focuses on describing the current research efforts at Sandia's wind energy department, which are primarily aimed at developing large rotors that are lighter, more reliable and produce more energy. I. Introduction Wind energy as a utility power source continued to expand dramatically in 2008. Figure 1 [1] shows the yearly and cumulative installed capacity in the United States from 1995 to 2007, with 2008's entry as an estimate. The actual installed capacity in the U.S. has exceeded most, if not all, expectations and predictions over the past several years. The 2008 number actually came in at 8.5 GW, as reported by AWEA (www.awea.org), well ahead of an estimated 6.5 GW. It is expected that the 2009 number will be down due to financial market pressures, but new orders are expected to pick up again in 2010. Installed wind energy capacity worldwide has also grown exponentially over the past few years, and BTM predictions [1] are that this growth will continue for many years (Fig. 2).

Renewable Electricity Futures Study. Volume 2. Renewable Electricity Generation and Storage Technologies

“…• Use of high-tech composite materials or curved blades to allow passive shedding of loads achieved through engineered blade deformation and twisting (Ashwill 2009) • Development of partial blade span actuation and sensing strategies to adapt to localized variability in wind speed and turbulence across the rotor disk (Buhl et al 2005;Lackner and van Kuik 2009) • Incorporation of trailing edge flaps or micro tabs coupled with sensors that can "see" the wind and preemptively react to changes in wind speed and turbulence (Andersen et al 2006;Berg et al 2009). …”

IEA Wind Task 26: The Past and Future Cost of Wind Energy, Work Package 2

“…Some weight reductions may be achieved by incremental design refinements and optimizations or the application of new materials with lower mass-to-strength ratios. More significant weight reductions might be achieved with designs that passively shed loads by twisting (Ashwill 2009) or that include partial blade span actuation (i.e., the ability to control different sections of a single turbine blade) coupled with sensing capacities that allow the rotor to adapt to variability in wind conditions and turbulence in different parts of the rotor disk (Buhl et al 2005, Lackner and van Kuik 2009, and UpWind 2011. Trailing edge flaps that react to the wind as it is moving towards the rotor rather than the wind that has already passed by could also assist in load shedding and ultimately weight reductions (Andersen et al 2006, Berg et al 2009).…”

Carbon nanotube reinforced hybrid composites: Computational modeling of environmental fatigue and usability for wind blades

“…A number of experimental and computational studies have been carried out to develop better materials for wind turbines [1][2][3][4][5][6][7]. Among various ideas to enhance the performances of the composite materials for wind energy applications, two approaches attract a growing interest of research community and industry: hybrid composites and nanoreinforced composites.…”

“…Hybrid composites (e.g., mixed carbon and glass fibers) allow to combine the advantages of both groups of fibers (for the case of carbon/glass composites, low price of glass fibers, low weight and high tensile strength and stiffness of carbon fibers) and compensate their weaknesses (again, high costs and low compressive strength of carbon fibers) [4][5][6][7][8][9][10][11][12][13][14][15][16][17]. So, Ong…”