BAR: Big Adaptive Rotor Project

BAR aims to to maximize the advantages of large-scale rotors and their potential for increased energy generation.

The project involves researchers from NREL, Sandia National Laboratories, Oak Ridge National Laboratory, and Lawrence Berkeley National Laboratory.

Wind turbine

Hanging on the leading edge. Science and engineering advances in rotor growth can increase capacity factors, or the amount of power a turbine outputs on average over the course of a year. Photo by Dennis Schroeder, NREL 27205

Building Better (Highly Flexible) Blades

The past few decades have seen substantial reductions in the cost of wind energy largely because of increases in rotor size. Increases in rotor size on the same machine rating lead to low-specific-power turbines that can reduce the cost of wind energy by creating a greater swept area which helps wind power plants more consistently capture wind energy, as well as access higher wind speeds at elevated heights.

The U.S. Department of Energy's BAR project seeks to overcome transportation challenges associated with the creation of the giant, land-based turbines of the future by exploring innovations like highly flexible blades that simultaneously boost wind energy capture while resolving transportation challenges of moving giant wind blades by rail.

Coding Advances for Larger Land-Based Wind

To help clarify and better articulate the science and engineering hurdles facing potential turbine concepts, researchers are using NREL's turbine design models OpenFAST and the Wind-Plant-Integrated System Design and Engineering Model (WISDEM) to model turbine performance and turbine system-level interactions.

BAR researchers also developed cOnvecting LAgrangian Filaments (OLAF), a new free-vortex wake module included in NREL's OpenFAST wind turbine simulation tool. OLAF models the turbine wake using particles connected via filaments and is programmed to generate realistic representations of large, flexible turbine blades, providing users an alternative to traditional aerodynamic models.

As an open source mid-fidelity tool, OLAF enables designers throughout the wind industry to use it to more accurately and predictably model their own designs, reducing their development costs, while further developing the software collaboratively.

Bar Project Team


Co-Project Lead: Nick Johnson

NREL research engineers include:

  • Ben Anderson
  • Pietro Bortolotti
  • Emmanuel Branlard
  • Scott Carron
  • Chris Kelley
  • Nicole Mendoza
  • Andy Platt
  • Kelsey Shaler.

Sandia National Laboratory

Co-Project Lead: Josh Paquette

Sandia National Laboratory research engineers include:

  • Evan Anderson
  • Ernesto Camarena
  • Chris Kelley.


Nick Johnson

Big Adaptive Rotor Co-Project Lead