EEI > Delivering The Future
Iowa Wind Turbine Reaches New Heights
March 2016

​MidAmerican Energy’s new wind farm in Adams County, IA includes a first for the company—a concrete wind turbine tower.
According to Mike Gehringer, MidAmerican Energy’s vice president of renewable energy, the concrete tower provides support for the tallest land-based wind turbine ever built in the country, and will be able to capture wind energy generated at higher altitudes.
“Advancements in turbine design and construction techniques are opening up new opportunities for development of renewable resources,” said Gehringer. “We want to continue to lead in bringing innovative energy solutions to our customers and the state of Iowa.”
MidAmerican Energy contracted with Siemens for the supply and construction of the concrete tower design. Gehringer said both companies view this tower as a prototype that could serve as a model at future wind farms and open low-to-medium wind resource areas of Iowa for future wind development.
“The process of building a concrete tower is quite different from the process we use to construct turbines with steel towers,” Gehringer continued. “Instead of building the tower sections in a factory and transporting them to the site to be fitted together, crews pour the concrete in segments and manufacture the tower onsite.”
Using concrete instead of steel provides the option to install a taller wind turbine that can capture more wind energy. “Generally speaking, the higher the altitude, the greater the wind resource available,” Gehringer explained. The 2.4 megawatt (MW) concrete tower turbine at the Adams wind farm measures 377 feet from ground to hub, compared to 263 feet for most of the turbines in use at other MidAmerican Energy wind farms. With blades extended, the turbine reaches a height of 554 feet, making it about as tall as the Washington Monument.
In addition to the local supply and construction of the Siemens concrete tower, Siemens sourced the concrete formwork from EFCO Corporation in Des Moines and supplied the wind turbine blades for the entire Adams project from the Siemens blade factory in Ft. Madison, Iowa.
The concrete turbine is one of 64 wind turbines that make up the 154-megawatt Adams wind farm, which was placed in service January 30, 2016.