Low Wind Speed Technology Phase II: Development of a 2-MW Direct-Drive Wind Turbine 

for Low Wind Speed Sites 

Northern Power Systems

Project Description: Previous design studies conducted by the U.S. Department of Energy (DOE) subcontractors have indicated that several new 

design configurations for wind energy technologies could offer significant 

opportunities for reducing the cost of energy (COE). These technology 

improvement opportunities include: reduction in the cost of and improvements in the efficiency of the drivetrain; increases in energy capture by 

increasing rotor diameter; and improved active wind turbine controls. 

The studies indicated that using several techniques can achieve these 

results. Many of these techniques are interrelated. For example, decreasing 

drivetrain weight can make the use of taller towers more cost effective, or 

introducing advanced rotor designs that decrease loads will allow greater 

rotor diameter, and hence, increased energy capture.

Consistent with this strategy, a team led by Northern Power Systems (NPS) 

has undertaken an effort to design, build, erect, and test a 2-MW wind turbine that integrates several technologies developed during earlier phases of 

the Low Wind Speed Technologies (LWST) project. The effort will utilize 

a high-energy-density, permanent-magnet, direct-drive generator based on 

work completed under the precursor WindPACT Program. In addition, the prototype will include an advanced power converter 

having insolated gate bipolar transitor (IGBT) active rectifier and line-side inverter stages that were developed and optimized 

under an LWST Phase 1 subcontract. Exploitation of these and other advanced technologies will increase energy capture, reduce 

erection and maintenance costs, capture other cost of energy advantages, and ultimately, generate electricity on a significantly 

more cost-effective basis than turbines using current technologies. The effectiveness of this design philosophy will be demonstrated in the final year of the subcontract, when a 2.2-MW prototype turbine will be tested at a low wind speed site in the 

United States.

Project Type: Prototype Development 

Total Project: $8,296,062 

Industry Cost Share: $2,654,011 

DOE Cost Share: $5,642,051 

Planned Project Duration: July 2005–June 2008

Contacts:

NREL/Sandia: Northern Power Systems:

Scott Schreck, NREL Peter Mattila, NPS

1617 Cole Blvd. 182 Mad River Park

Golden, Colorado 80401 Waitsfield, Vermont 05673

303-384-7102 802-496-2955

scott_schreck@nrel.gov Pmattila@northernpower.com

Current Status: Project Underway

Concept illustration of the NPS 2-MW direct-drive wind turbine.

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.

DOE/GO-102006-2232

March 2006