Low Wind Speed Technology Phase II: Reducing Cost of Energy through Rotor 

Aerodynamics Control

Global Energy Concepts, LLC

Project Description: The WindPACT Rotor Study evaluated a wide range of wind turbine configurations and their impact on overall cost of energy (COE). These studies assumed baseline approaches consistent with current designs that use tapered twisted 

blades and collective pitch actuation for aerodynamic control. A wide range of other technologies can modify rotor aerodynamics 

and geometry, and may reduce COE. This study explores two major technologies:

• Devices or methods that can be used to actively alter the local aerodynamic properties of the rotor blade. These devices would 

typically have response times about the same as, or faster than, a full-span, variable-pitch system. Reduced systems loads, 

increased energy capture, or some combination of these may reduce COE. 

• An actively controlled variable-diameter rotor. Its primary advantage is increased energy capture; the engineering challenge is 

to mitigate cost increases caused by increased loading and added mechanical systems.

The goals of this project are to: 

• Develop detailed performance and loads for active aerodynamic and geometry 

control parameters at a rating consistent with the current market for utility-scale 

turbines.

• Incorporate the most current technology in controls, materials, and mechanisms. 

• Identify technical barriers to achieving Low Wind Speed Technology Project COE 

targets, and suggest ways to surmount these barriers.

Researchers and turbine designers can use the results with COE models to determine 

how much such systems could add to the cost of a wind turbine without increasing 

the COE, and determine how much a proposed approach is likely to reduce the COE. 

Project Type: Conceptual Design Study

Total Project Budget: $199,678

Industry Cost Share: $0

DOE Cost Share: $199,678

Planned Project Duration: August 2004–March 2006

Contacts:

NREL/Sandia: Global Energy Concepts, LLC:

Scott Schreck, NREL Dayton Griffin, GEC

1617 Cole Blvd. 5729 Lakeview Dr. NE, Suite 100

Golden, Colorado 80401 Kirkland, Washington 98033

303-384-7102 425-822-9008

Scott_schreck@nrel.gov dgriffin@globalenergyconcepts.com

Current Status: Project Underway

A Strong Portfolio for a Strong America • Energy efficiency and clean, renewable energy will mean a stronger economy, a cleaner environment, and greater energy 

independence for America. Working with a wide array of state, community, industry, and university partners, the U.S. Department of Energy’s Office of Energy Efficiency 

and Renewable Energy invests in a diverse portfolio of energy technologies.

For more information contact EERE Information Center • 1-877-EERE-INF (1-877-337-3463) • www.eere.energy.gov

Produced for the U.S. Department of Energy by the National Renewable Energy Laboratory, a DOE national laboratory

Printed with a renewable-source ink on paper containing at least 50% wastepaper, including 10% post consumer waste.

Candidate devices for active aerodynamic control.

DOE/GO-102006-2195

March 2006

Micro-Tabs

Vortex Generators

‘Morphing’ trailing-edge shape