Iowa State professor researching new wind turbine design

Source: By Julie Ferrell, Staff Writer, Ames Tribune • Posted: Monday, October 6, 2014

One Iowa State University professor is leading the development of a new way to increase national wind energy production.

Sri Sritharan, ISU’s Wilson Engineering professor in civil, construction and environmental engineering and leader of the College of Engineering’s wind energy initiative, is developing new details for his Hexcrete project, a concrete alternative to create taller wind turbines across the country.

Along with graduate student researcher Grant M. Schmitz, Sritharan has been developing the product for the last six years. By using concrete instead of the current steel model to create wind turbines, Sritharan’s design could allow future turbines to reach 100 meters (328 feet), 20 meters (65 feet) taller than current models seen across the country.

The idea came to Sritharan following his 2008 endowment, which was given in honor of Boeing’s former CEO Thornton “T” A. Wilson. At the same time, Sritharan was approached about using concrete as a viable resource for building turbines, and he decided to seize the opportunity.

“I thought with the money coming in and the endowment coming from T. A. Wilson, I knew he was passionate about wind and aircraft. I just thought I should do something related to it,” he said.

Sritharan’s design is composed of a hexagonal structure, formed by high-strength concrete. The shape allows for easy assembly and has a flat surface on each of its six sides, making it easier to transport than the curved steel shells used in current models. Because the structure is also stronger, Sritharan’s turbine also allows for taller towers. The current plan is to develop 100-meter-tall models, but Sritharan said he hopes to eventually create designs capable of reaching 120 or even 140 meters, or about 460 feet.

The new concrete design also allows for easier and cheaper transportation, Sritharan added. Current turbines are transported in three large segments but when designs for larger turbines are finalized, companies will need to find new methods of transportation.

“If you take the same concept and increase the height (of the turbine) to 100 meters or above, the base becomes so big that you cannot actually transport because it won’t clear the vertical clearance on bridges,” Sritharan said.

The concrete model would not require special transportation, but could instead use typical semi-trucks.

Sritharan said the new design could also help reduce costs the U.S. spends on international steel for current models. Not only could the Hexcrete concrete pieces be created in the country, Sritharan said, but they could likely be created by local companies surrounding each turbine station.

“We could find a precaster within 200 miles of any site in the U.S.,” he said. “Right now, we bring towers from Taiwan. Taiwan to 200 miles is a big difference.”

Sritharan said the U.S. Department of Energy is interested in reaching at least 100 meters, as wind conditions are more favorable the higher the turbine reaches. By increasing turbine models to 100 meters, wind energy production is estimated to increase by 10 percent. For his research, Sritharan has been awarded an 18-month, $1 million grant from the Department of Energy, and is also being supported by the Iowa Energy Center, with contributions from Lafarge North America Inc. in Calgary, Alberta, Canada. The research also has partners spanning the country, ranging from Siemens in New Jersey to Nebraska and Washington.

Sritharan said the new design has the potential to reach untapped areas across the country, where the current steel model may not be effective. The creation of new fields could help meet the Department of Energy’s goal to increase the nation’s current production of 60 gigawatts by five- or six-fold in the next few decades. Sritharan added that Iowa, which currently produces 5 gigawatts of energy from wind power, has a goal of reaching 20 gigawatts in the coming decades.

“There will be multiple-fold increase in the next 10 to 20 years,” Sritharan said, “so what we’re trying to do is ask, can we actually provide a means to do that cost-effectively and continue to reduce the wind energy cost

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