Go-With-the-Flow Wind Turbine, Conceived by UVA Prof, Completes Successful Demo

Eric Loth Headshot

About 15 years ago, University of Virginia engineering professor Eric Loth started thinking about how he could help with climate-related dilemmas, which led to his big idea about improving the design of wind turbines. What if a turbine’s blades could gracefully bend when subjected to high winds, morphing with the weather conditions like palm trees do during a hurricane? After all, it’s the blustery winds at the coast where the greatest energy opportunities lie.

Loth’s Personal Challenge

Given the billions of dollars required to develop wind farms, investors want turbines that can last their full potential lifespans, about 25 years, while maximizing energy production at a low cost. One way to do that is by using the longest blades feasible in the strongest winds possible.

But traditional wind turbines have had a problem: The bigger the blades get, the more likely they are to strike the tower supporting them, especially in high winds.

The personal challenge for Loth was, essentially, go big or go home.

He went big, with rotors the size of a football field. Then he went to the National Wind Technology Center in the mountains near Boulder, Colorado, where a multi-institutional research team put them to the test at one of the best wind turbine test facilities in the world.

UVA partnered with the University of Texas at Dallas, the University of Colorado, the Colorado School of Mines, the University of Illinois and Sandia National Labs. Together, these institutions took the concept from paper and computer models to fabrication and execution of the 20%-scale demonstrator.

The biggest wind turbines currently being demonstrated or in use (at the so-called “extreme scale”) typically produce around 15 or 16 megawatts of power, Loth said, although European engineers are working on a 22-megawatt design, he added.

At 25 megawatts, SUMR would be taller than the Eiffel Tower, which is just over 1,000 feet tall.

While an increase to 25 megawatts is a significant step, a jump to 50 megawatts would be an industry-changing leap forward. And Loth said an upcoming journal publication by the team will show that such a design is possible as well.

A turbine that size could reduce the cost of reaping energy by as much as 20%.

Bigger (and Lighter) Is Better

Loth, who next month steps down as chair of the Mechanical and Aerospace Engineering Department, is a Rolls-Royce Commonwealth Professor and also director of UVA’s Fluids Research Innovation Lab. He illuminated SUMR’s advantages as compared to other wind turbines. (And for the record, he said, it’s pronounced “summer” – not that he would ever dispute anyone who said it differently.)

SUMR’s secret is a patented, aero-elastically flexible downwind design. “Typical turbines are upwind,” Loth said. “We flip the script and place them downwind.”

Doing so lightens the load and permits their longer length, as does the construction of the blades themselves, which are built in segments and hinged. This reduces the mass of the rotor relative to the power it can generate.

“Saving system mass saves money,” Loth said, quoting an aerospace engineering truism.

However, a downwind orientation has traditionally caused some problems – namely noise, wind flow obstruction issues (due to the closeness of the blades to the tower, which is upwind) and electronic-controlling issues.

SUMR has overcome all three, Loth said.

“In terms of noise, our demonstrator turbine turns out to be very quiet,” he said. “And we designed the blades to be far enough apart, so we got rid of the tower-shadow effect. It also has more intelligent control systems. The software is levels above what we could do 10 or 20 years ago.”

Loth said the project had to be scaled down to fit within the Department of Energy’s $6 million project budget. Sizing up, he noted, is just a matter of careful extrapolation.

Juliet inspecting a wind turbine prototype

Juliet Davis, who has worked on Loth’s SUMR wind turbine project, holds the latest model. (Photo by Chris Tyree)

The Wave of the Future

Given the size of the turbines, their ultimate rollout in perhaps a decade or more won’t be in your backyard, but more likely about 25 miles out to sea. There, the turbines would be less visible to coastal residents and vacationers, and mostly out of the path of migratory birds, which tend to hug the coastline during their travels.

“I think that’s going to happen for sure,” Loth said of U.S. widescale offshore wind farming, which he expects to see span the Eastern coastline from North Carolina to Massachusetts.

Loth continued to refine the idea. Now, having completed a successful demonstration of his 10-story tall Segmented Ultralight Morphing Rotor, he is another step closer to making the turbine a reality – one that could provide massive amounts of clean wind energy for the world.

As a Department of Energy demonstration project, now wrapping up, SUMR has demonstrated that its highly flexible blades and control system not only work, but that they can be adapted to an extreme-scale, 25-megawatt power-generating system, which would be a record in terms of size. Last month for the first time, Loth and partners publicly shared evidence of their successful testing at an annual international meeting in the Netherlands.

“I think that the project has gone really well,” Loth said of the six-year study, conducted under the DOE’s Advanced Research Projects Agency.

That may be an understatement. His turbine, in fact, operated nonstop for two years, including surviving an unexpected 110-mph gust and a bomb cyclone.

SUMR now appears to be a leading design in the international race to optimize offshore wind power.

Dominion Energy is currently endeavoring to build a large offshore wind power project in the United States, off Virginia Beach.

These Giant Wind Turbines, Inspired by Palm Trees, May Be the Future of Renewable Energy

Video: These Giant Wind Turbines, Inspired by Palm Trees, May Be the Future of Renewable Energy

SUMR is one example of the type of projects UVA is encouraging through its Grand Challenges Research Investments, which are meant to leverage the capacity for the University’s brightest minds to innovate solutions to some of the biggest problems that confront the world. UVA announced recently it will apply $60 million toward the development of clean-energy research and other measures to promote environmental resilience and sustainability.

Loth joined the UVA faculty in 2010. In 2015, Popular Science named him one of its 12 “Brilliant Minds Behind The New Energy Revolution” for his promising turbine design.

Then and now, he gives ample credit to his partners, who have helped him solve problems and publish papers that have moved the project forward. Current or recent UVA doctoral students who worked on the demonstration project include Chao “Chris” Qin, now a UVA research scientist, and Vanessa Awate, Michael Jeong, Meghan Kaminski, Carlos Noyes and Juliet Simpson.

“Like so many others, we want to do whatever we can to save the planet, and we are excited to do so with wind,” Loth said.

Loth first worked on wind turbine projects as an undergraduate in aerospace engineering at West Virginia University, nearly 40 years ago. His graduate degrees are in aerospace engineering as well. He earned his master’s from Pennsylvania State University and his doctorate from the University of Michigan.

But wind left his life as he worked on other types of engineering projects, not only for major universities, but for the Naval Research Laboratory in Washington, D.C., and other employers. He has developed jet propulsion systems, even spacecraft nozzles. He holds several U.S. patents.

Like a turbine, though, his career has circled back. SUMR could be the innovation of his that changes the world, although Loth remains modest about the possibility.

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