January 06, 2017

Testing Taller Wind Turbines — By Breaking Them Apart

 

Emma McGrath, Communications Fellow

Donning hard hats and protective goggles, in a 4,000 square-foot research lab packed with steel and concrete, a team of Northeastern University researchers is preparing for failure.

You know, the structural kind.

At the Structural Testing of Resilient and Sustainable Systems (STReSS) Lab in Burlington, Mass., a team of engineers and PhD students has been collecting cutting-edge data about wind turbines; how to make them a better, stronger and less expensive part of the renewable energy landscape.

They’re working to solve a well-known problem: the kinds of turbines we need are too big for transport, making wind projects costlier and more difficult to carry out.  

Stronger winds blow at high altitudes, so the taller that turbines are built, the more energy they can access. But taller towers need to be proportionally wider in diameter, making them too large to fit under most highway overpasses. The current fix, making tower walls thicker while keeping the diameter narrow, dramatically increases weight and production cost.

Originally designed by Keystone Tower Systems – then a group of Massachusetts Institute of Technology researchers – the solution involves a modification of spiral welding, rolling steel sheets into a tapered, “conical tower.” The process is highly automated, using one-tenth of the labor needed to construct traditional towers.

The sheets can be of varying thickness, too, and can be assembled directly at a wind turbine site, eliminating the need to transport a completed structure. This enables the building of taller turbines -- up to 460 feet -- that can generate 30 to 50 percent more energy than shorter models.

Northeastern’s STReSS Lab was tapped by Keystone to test the towers’ limit state -- what kind of, and how much, fatigue they can endure before they buckle under pressure.

Previous research on slender turbine towers, and spirally welded towers in particular, is lacking in volume and quality. The STReSS Lab team is working to bridge these gaps. The ultimate goal: a wind turbine that’s low-cost and easy to assemble, resilient enough to withstand the elements, and tall enough to generate the most energy possible.

Last month, with the help of a $96,000 grant from the Massachusetts Clean Energy Center, Keystone successfully installed its first demonstration turbine at the MIT-owned Bates Linear Accelerator Center in Middleton, Mass.

High costs and logistical hurdles are among the toughest challenges in the clean energy sector. Innovative ideas -- and the trailblazing research that makes them a reality -- give the entire industry a leg up.