NREL Automates Wind Turbine Blade Finishing Operation

ARVADA, CO—Engineers at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) are using robots to improve the consistency of wind turbine blades. Although robots have been used by the wind energy industry to paint and polish blades, automation has not been widely adopted.

In the new application, a six-axis machine safely trims, grinds and sands blades. Those steps occur after the two sides of the blade are made using a mold and then bonded together.

Traditionally, post-molding operations require workers to perch on scaffolding and wear protective suits, including respiratory gear.

“This work is critical to enable significant U.S.-based blade manufacturing for the domestic wind turbine market,” says Daniel Laird, director of the National Wind Technology Center at NREL.

“Though it may not be obvious, automating some of the labor in blade manufacture can lead to more U.S. jobs, because it improves the economics of domestic blades vs. imported blades.”

“The motive of this research was to develop automation methods that could be used to make blades domestically at a cost competitive price,” adds Hunter Huth, a robotics engineer at NREL who worked on the R&D project. “Currently, offshore blades are not produced in the U.S. due to high labor rates.

“The finishing process is very labor intensive and has a high job-turnover rate due to the harsh nature of the work,” explains Huth. “By automating it, domestic offshore blade manufacturing can become more economically viable.”

The research was conducted at NREL’s Composites Manufacturing Education and Technology facility. A six-axis robot worked on a 5-meter-long blade segment.

Wind turbine blades are considerably longer, but because they bend and deflect under their own weight, Huth says a robot would have to be programmed to work on the bigger blades section by section.

Huth and his colleagues used a series of scans to create a 3D representation of the position of the blade, and to identify precisely the front and rear sections of the airfoil. Then, they programmed the robot to perform a series of tasks, after which it was judged on accuracy and speed.

The engineers found areas for improvement, particularly when it came to grinding. For instance, the robot ground down too much in some parts of the blade and not enough in others.

“Not everything operated as well as we wanted it to, but we learned [how] to make it meet or exceed our expectations,” claims Huth.

“As we’ve gone through this research, we’ve been moving the goal posts for what this system needs to do to be effective,” says Huth.

According to Huth, an automated system would provide consistency in blade manufacturing that is not possible when humans are doing all the work. For instance, a robot would be able to use “tougher, more aggressive abrasives” than a human could tolerate.