Wind Energy Reaches Greater Heights

Wind turbines across the globe are being made taller to capture more energy from the stronger winds that blow at greater heights.

But it’s not easy, or sometimes even economically feasible, to build taller towers, with shipping constraints on tower diameters and the expense involved in construction.

Now Keystone Tower Systems — co-founded by Eric Smith, Rosalind Takata, and Alexander Slocum, the Pappalardo Professor of Mechanical Engineering at MIT — is developing a novel system that adapts a traditional pipe-making technology to churn out wind turbines on location, at wind farms, making taller towers more economically feasible.

Keystone’s system is a modification of spiral welding, a process that’s been used for decades to make large pipes.  In that process, steel sheets are fed into one side of a machine, where they’re continuously rolled into a spiral, while their edges are welded together to create a pipe — sort of like a massive paper-towel tube.

Developed by Smith, Takata, and Slocum — along with a team of engineers, including Daniel Bridgers and Dan Ainge — Keystone’s system allows the steel rolls to be tapered and made of varying thickness, to create a conical tower.  The system is highly automated — using about one-tenth the labor of traditional construction — and uses steel to make the whole tower, instead of concrete.  “This makes it much more cost-effective to build much taller towers,” says Smith, Keystone’s CEO.

With Keystone’s onsite fabrication, Smith says, manufactures can make towers that reach more than 400 feet.  Wind that high can be up to 50 percent stronger and, moreover, isn’t blocked by trees, Smith says.  A 460-foot tower, for instance, could increase energy capture by 10 to 50 percent, compared with today’s more common 260-foot towers.

“That’s site-dependent,” Smith adds.  “If you go somewhere in the Midwest where there’s open plains, but no trees, you’re going to see a benefit, but it might not be a large benefit. But if you go somewhere with tree cover, like in Maine — because the trees slow down the wind near the ground — you can see a 50 percent increase in energy capture for the same wind turbine.”

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