Saturday, June 22

Professor Looks to Concrete in Designing Taller Wind Turbines

The next push in renewable energy may be supported by an unlikely material: concrete.

Midwest Energy News reported Oct. 20 that Sri Sritharan, an engineering professor at Iowa State University, is working on a modular tower design for wind turbines that would allow them to reach above the 80-meter limit of current steel towers.

Sritharan has developed two pieces that can be precast from concrete, a panel and a column, that can be assembled in as many combinations as are necessary to reach the desired height.

“It’s flexible,” he told Midwest Energy News. “If you’re using a GE turbine, you use one set of dimensions. If you’re using a Siemens turbine, you have a different set of dimensions.”

The Limitations of Steel

Steel cannot be used to create taller towers because steel towers are transported via specialized trucks, typically in only three sections. Since taller towers must also have wider bases — the current maximum height requires a base of about 14 feet — these trucks would no longer suffice.

The problem is not the width of the truck bed, but rather the overhead clearance heights of highway overpasses. Since steel is manufactured in only a few places in the U.S., long-distance transportation is nearly always necessary.

“When the tower gets wider, you cannot transport it. Period,” said Sritharan.

Onward and Upward

Sritharan predicts that his modular design could allow towers of 100 or 120 meters, allowing wind turbines to reach the more consistent wind patterns of higher air.

There may be cost benefits as well, since concrete is often manufactured locally. “You can manufacture these towers within a couple hundred miles of where you want to build the tower,” Sritharan said, pointing to savings in shorter transportation distances by traditional tractor-trailers.

There is a concrete prototype turbine, built by Acciona Wind Power, near Iowa City.

Sritharan’s research team has accelerated its pace, courtesy of a $1.25 million grant from the U.S. Department of Energy, and says the design will be market-ready in about two years.

Concrete has been used in construction for thousands of years due to its strength — the dome of the famous Roman Pantheon is even made of over 4.5 metric tons of non-reinforced concrete.

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