In late 2014, we described how precast concrete is helping wind turbine towers reach new heights. By selecting precast in lieu of steel, owners can construct towers that reach more than 330 feet, where steadier wind conditions result in higher overall energy output.
Since then, Sri Sritharan, a professor at Iowa State University and a member of the College of Engineering’s Wind Energy Initiative, has expanded his research into the Hexcrete system. The tower consists of several precast concrete components manufactured with high-strength or ultra high performance concrete. The system offers many advantages, including:
- Simplified transportation.
- Easy tower assembly on site.
- Reduced costs.
As part of a $1 million grant from the U.S. Department of Energy he obtained for his research, Sritharan and his team recently put the Hexcrete system through a series of stress and fatigue tests. One full-scale test (shown above) examined design assumptions and verified the force transfer in a Hexcrete cell. The other test involved taking a 12-foot-high, 6.5-foot-wide precast section and applying 100,000 pounds of force to it every 1.25 seconds. Sensors attached to the unit collected data for weeks, and, according to Sritharan, the precast performed to expectation. Additional fatigue tests to ensure the structural integrity of the precast towers are ongoing.
The DOE claims that all 50 states in the U.S. can benefit from wind power with increased hub heights, something that can be made possible with precast. But in order to do so, towers must be able to reach approximately 460 feet high. That height would make turbines viable for areas of the U.S. previously not considered for wind energy production. Sritharan’s research team is currently designing Hexcrete towers to reach this new height.
For Sritharan, this means two things: greater wind energy production for a reduced cost and the ability for precasters across the U.S. to manufacture a new product line. This would ultimately benefit local economies.
“By doing columns and panels like we are using, most precasters can produce (the Hexcrete system),” he said.
Later this year, Sritharan will continue his research by hosting workshops. Additional information is available on the project website.
A video depicting a Hexcrete installation can be viewed below.