December Newsletter

Up to Wind Speed is a quarterly newsletter from NREL's National Wind Technology Center (NWTC).

For more than two decades, research conducted by NREL's Wind Program has helped industry advance wind energy technology, increasing reliability and lowering the cost of energy. As we continue our efforts with the wind industry in 2011, we will keep you up to speed on what's happening in wind energy research and development and provide you with links to NWTC's recent publications.

In this issue:

• Vendors Selected for Dynamometer Upgrade
• Labs Collaborate to Improve Theoretical Blade Models
• Wildlife Among the Turbines
• Distributed Wind Works – Recent Workshops
• Nebraska Wind for Schools Surpasses Goals
• Recent Publications

Vendors Selected for Dynamometer Upgrade

Work proceeds on the development and construction of an upgraded 5-MW dynamometer facility at the NWTC. Brad Foote Gearworks, a Broadwind Energy Company, has been awarded the contract for the final design and fabrication of a 5.8-MW gearbox. The contract to perform due diligence on the gearbox design and fabrication has been awarded to Romax. ABB has been awarded the contract for fabrication of a 6-MW motor and its associated regenerative variable-speed drive. BEW Engineering has been awarded the contract for due diligence on the motor and drive system design, fabrication, and commissioning.  BEW also won a contract for the conceptual design of control and data acquisitions systems and for the dynamometer upgrade. A contract will also be awarded for the final design and fabrication of a non-torque loading system. An RFP was issued in November to a short list of three pre-qualified companies for the dynamometer building design and construction. The dynamometer upgrade is scheduled for completion in 2012.

Labs Collaborate to Improve Theoretical Blade Models

The NWTC, in collaboration with Sandia National Laboratories (SNL), is working to develop a publicly available data set that relates the deflection of a wind turbine blade with respect to an applied load. Using SNL's 9-meter CX-100 blades, which have been extensively modeled and tested, the team will attempt to capture an experimental data set of deflections, rotations, and loads, with a focus on the inboard 30% of the blade, to develop a detailed stiffness distribution of the blade. In addition, it will be used to investigate the accuracy of current theoretical blade models and identify potential improvements such as cross-sectional warping.

Historically, many multi-body structural dynamics modeling programs have employed Euler-Bernoulli (EB) beam theory for three-dimensional motion predictions of wind turbine blades. The degrees of freedom in this theory include flapwise and edgewise deflection and rotation, spanwise deflection, and torsion about the span axis. It represents applied forces and moments in (and about) the flapwise, edgewise, and spanwise directions. The central assumption of the EB beam theory is that the flap-edge cross-sectional plane, defined by the flapwise and edgewise axes, always remains perpendicular to the spanwise axis at the intersection of the spanwise axis and the flap-edge cross-sectional plane. Furthermore, the cross-sectional plane is assumed to remain a plane. These assumptions are typically valid for thin cross-sections with small angles of deformation. However, for real structures, thick structures, and large deflections, these assumptions are generally not valid due to the occurrence of Timoshenko-type sectional motion and cross-sectional warping.

This collaborative effort between NREL and SNL will provide the wind industry with a reference set of blade data that can be utilized for improvement of structural blade models and to validate the theoretical assumptions typically employed.

Wildlife Among the Turbines

Sharing their home along the front range of the Colorado Rockies with the NWTC research facilities, creatures both great and small live among—and fly by—turbines also both great and small.

From large predators like coyotes and mountain lions to the smallest mice and nesting birds, life abounds here.

NREL senior biologist Brenda Beatty and other NREL biologists are conducting studies to assess the site's mammals, birds, and bats.

Four avian studies currently in progress include fixed-point, raptor, breeding, and mortality surveys. These studies assess the kinds of birds using the site and in which seasons. The fixed point surveys record a list of species and their locations, from visual sitings at 12 points on and off the site, over the course of a year. The raptor survey, completed in April of this year, documented raptor migration through the site. In May and June of 2011, walking transects will be conducted to look for nesting birds in the trees, shrubs, and grasses on the site.

Mortality surveys for birds and bats typically are conducted at wind farms after wind farm installation. Observers monitor the area beneath the turbines and meteorological towers over the course of several years looking for avian and bat fatalities. "Although the NWTC is a research facility, and not a wind farm, the mortality surveys will help to document whether or not mortalities are occurring at the wind site," explains Beatty.  Mitigation of fatalities is important because most birds onsite are protected by the Migratory Bird Treaty Act, or the Bald and Golden Eagle Protection Act.  As a federal facility, NREL complies with these protections.  NREL also has a commitment to environmental stewardship during the course of its activities.  For bat species using the site, it will be important to understand if mortalities are occurring and if so, to determine the population level impacts.  This may become important in the future if white-nose syndrome (a fungus affecting bats in the northeastern U.S.) comes to Colorado. Biologists hope to establish a good baseline of site conditions concerning bats. 

Site vegetation studies are also being conducted to map individual plant communities including weed areas in need of treatment.  Wildlife surveys are currently being done to determine small mammal populations (using trap and release methods), deer and elk numbers, large predator counts (using motion-detector cameras), and bat surveys (using detectors that measure the echolocation signals of the flying mammals).

Biologist's efforts and the results of these studies will be used to describe the NWTC's biological resources in an update to NREL's Sitewide Environmental Assessment, which will be initiated early next year.

Distributed Wind Works

Recent Workshops
The DOE Wind Power Program held a workshop on October 28 to develop a suggested list of high-impact, top-down solutions for federal policy, legislation, and actions that can be implemented to streamline distributed wind (small and midsize) turbine deployment. The compilation of solutions will be considered by policymakers and DOE. Specifically, the workshop addressed deployment barriers: zoning, permitting, installation, site assessment, interconnection, net metering, and financing.

The public was invited to brainstorm and develop concepts that would benefit from federal legislative involvement to accelerate distributed wind deployment. In addition, workshop participants considered strategies to disseminate distributed wind energy education to local officials.

On August 11-12, the Built-Environment Wind Turbine (BWT) workshop was held at NWTC and included both international and national experts from academia, national labs, wind consultants, architects, modeling companies, and public utilities.

The workshop began the process of developing a focused roadmap on turbines in the built environment, including barriers, action plans, and potential collaborators. Top-level technical presentations on BWT theory, designs, and empirical results of BWT turbines. Additionally, computational fluid dynamic (CFD)/mesoscale modeling and measurements of the built environment were given to determine what work had already been accomplished and what future work is needed in terms of improving safety, understanding wind resource, and measuring costs.

This workshop was co-organized by Lawrence Livermore National Laboratory, University of California-Davis engineers, and NREL Distributed Wind Team members.

Nebraska Wind for Schools Surpasses Goals

Federal and state grant programs funded a record number of wind turbine projects across Nebraska through the Wind for Schools program. Since 2007, more than 21 partner schools have installed, or are in the process of installing, wind turbines on their campuses. Interested rural schools incorporate wind curricula, stimulating interest in renewable energy at the K-12 school level. College student teams facilitate the wind application process, providing college juniors and seniors with hands-on experience with which they can enter the wind industry workforce.

The Nebraska project exceeded its original program goal to add three to five schools annually. Wind Powering America sponsors the Wind for Schools project to raise awareness in rural America about the benefits of wind energy while simultaneously developing a wind energy knowledge base in future leaders of our communities, states, and nation.

Recent NWTC Publications

• 2009 Wind Technologies Market Report.

• 2009 Wind Technologies Market Report: Executive Summary.

• Advanced Unit Commitment Strategies for the U.S. Eastern Interconnection: Preprint.

• Advancing Wind Integration Study Methodologies: Implications of Higher Levels of Wind.

• Aeroacoustic Noise Measurements of a Wind Turbine with BSDS Blades using an Acoustic Array. AIAA 2010-642.

• Assessment of Offshore Wind Energy Resources for the United States.

• Benefit of Regional Energy Balancing Service on Wind Integration in the Western Interconnection of the United States: Preprint.

• Blade Pitch Control with Preview Wind Measurements. AIAA 2010-251.

• Blade Testing at NREL's National Wind Technology Center (NWTC) (Presentation).

• Combining Balancing Areas' Variability: Impacts on Wind Integration in the Western Interconnection.

• Comparative Assessment of Direct Drive High Temperature Superconducting Generators in Multi-Megawatt Class Wind Turbines.

• Conventional Hydropower Technologies (Fact Sheet). Wind And Water Power Program (WWPP).

• Development of an Equivalent Wind Plant Power-Curve: Preprint.

• Development of Regional Wind Resource and Wind Plant Output Datasets for the Hawaiian Islands.

• Earthquake Response Modeling for a Parked and Operating Megawatt-Scale Wind Turbine.

• Examples of Wind Energy Curtailment Practices.

• Gearbox Reliability Collaborative: Gearbox Inspection Metadata.

• Investigation of Various Wind Turbine Drivetrain Condition Monitoring Techniques.

• Large-Scale Offshore Wind Power in the United States: Assessment of Opportunities and Barriers.

• Large-Scale Offshore Wind Power in the United States: Executive Summary.

• Low Frequency Shedding Prompted by Three-Dimensionality under Rotational Augmentation. AIAA 2010-640.

• Low Wind Speed Turbine Developments in Convoloid Gearing: Final Technical Report, June 2005 - October 2008.

• Market Characteristics for Efficient Integration of Variable Generation in the Western Interconnection.

• New England Wind Forum: A Wind Powering America Project - Newsletter #6 - September 2010, (NEWF). Wind and Water Power Program (WWPP).

• Small Wind Independent Testing (Fact Sheet). National Wind Technology Center (NWTC). (2010).

• Testing Further Controls to Mitigate Loads in the Controls Advanced Research Turbine. AIAA 2010-252.

• Unique Dynamometer Enables Rapid Advancement of Industry Leader; The Spectrum of Clean Energy Innovation (Fact Sheet).

• User's Guide to MBC3: Multi-Blade Coordinate Transformation Code for 3-Bladed Wind Turbine.

• Utilizing Load Response for Wind and Solar Integration and Power System Reliability.

• Water Power for a Clean Energy Future (Fact Sheet). Wind And Water Power Program (WWPP).

• Wind Energy Ordinances (Fact Sheet). Wind And Water Power Program (WWPP).

• Wind Energy-Related Atmospheric Boundary Layer Large-Eddy Simulation Using OpenFOAM: Preprint.

• Wind Farm Wake Simulations in OpenFOAM. AIAA 2010-825..

• Wind for Schools Project Curriculum Brief (Fact Sheet). Wind And Water Power Program (WWPP).

• Wind Resource Assessments and Mapping; Knowing and Showing Where the Wind Resource Can be Found (Fact Sheet). National Wind Technology Center (NWTC).

• Wind Turbine Design Innovations Drive Industry Transformation; The Spectrum of Clean Energy Innovation (Fact Sheet).

• Wind Turbine Generator System Duration Test Report for the Gaia-Wind 11 kW Wind Turbine.

• Wind Turbine Safety and Function Test Report for the Mariah Windspire Wind Turbine.

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