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sts.components.contact.mr.placeholder Sebastian Webel
Mr. Sebastian Webel

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Pictures of the Future
The Magazine for Research and Innovation
 

Sustainable Power Generation

Hexcrete: A New Concept for Taller Wind Turbine Towers

In the U.S. today, steel tubular towers with a hub height of 80 meters dominate utility-scale wind farms (picture: a Windfarm in Iowa / U.S.). A research-project is currently working on a concept for harvesting wind energy at 120 to 140 meter rotor hub heights, where favorable wind conditions exist.

Wind power’s potential can be more fully realized with higher towers. Hexcrete Tower is designed to address this issue.

Taller turbine towers would not only allow access to higher wind speeds and steadier conditions, but also to increased wind production time and maximized opportunities to harvest energy. This is true for parts of Europe and the United States where favorable wind conditions exist above 100 meters and electricity demand is relatively high. With this in mind, Corporate Technology (CT US) has partnered with Iowa State University to adapt the Hexcrete Concept — a structural engineering innovation used for tall bridge towers in suspension and cable-stayed bridges — to taller wind turbine towers.

The goal of the “Hexcrete Tower for Harvesting Wind Energy at Taller Hub Heights” project is to create a new wind turbine tower design and manufacturing concept for harvesting wind energy at 120 to 140 meter rotor hub heights, and reducing the per-kilowatt-hour cost of building and operating wind towers in the United States. CT US is performing design analysis and optimization for the wind tower designs that are created for this effort.

“For a long time, turbine manufacturers have aspired to building taller towers, because wind resources are more consistent and dependable at higher altitudes. This project has real potential for making this plan a reality,” said Kurt Bettenhausen, Head of the Automation & Control Technology Field at CT US. 

Siemens Corporate Technology has partnered with Iowa State University to adapt the Hexcrete Concept — a structural engineering innovation used for tall bridge towers in suspension and cable-stayed bridges — to taller wind turbine towers.

Concrete instead of Steel

In the U.S. today, steel tubular towers with a hub height of 80 meters dominate utility-scale wind farms. The towers are manufactured and transported in three long segments with a base diameter of approximately 4.1 meters, which is just under the vertical clearance allotted on state highways. If the currently prevailing towers were lengthened by an extra 20 or 60 meters, wind turbines could produce more energy and make wind energy more economically viable in places where it currently is not. However, modularizing steel tubes in the field that require vertical seams is expensive and demands a high degree of quality control. 

In view of this, Iowa State University Professor Sri Sritharan is working with a Siemens CT US team led by Suraj Musuvathy to make taller wind turbines a reality. “The key to taller towers is to build with concrete instead of steel,” says Sritharan, who is developing a tower made of prefabricated modular concrete members that could be assembled to reach a desired hub height.

The Hexcrete Tower is named for its hexagonally-shaped, pre-tensioned concrete columns and hexagonally-shaped tower sections. The entire tower is assembled using prefabricated columns and panels made from High Performance/Strength Concrete and/or Ultra High Performance Concrete.

The Advantages of Modularity

The CT team, with support from Siemens’ Wind Power and Renewables division, is working on 3D modeling, simulation and optimization algorithms to perform design space exploration of the modular concept, with a view to finding design parameters that minimizes the per-kilowatt-hour cost of building and operating wind towers while also satisfying structural and design criteria. Modularity lends to increased flexibility regarding both the construction and transportation of the towers.

The key to taller towers is to build with concrete instead of steel, who is developing a tower made of prefabricated modular concrete members that could be assembled to reach a desired hub height. Advantage: Unlike steel, concrete is widely and locally available across the U.S., which leads to shorter transport routes and reduced costs. Picture: transport of a conventional tower module.

A modular concrete system could be transported on a tractor-trailer and would eliminate the need for expensive specialized trailers that currently carry steel towers — consequently addressing the constraints and roadblocks associated with taller towers.  By using a modular system of concrete members, the base of the tower could be built wider than 4.1 m, which would facilitate even taller towers. And a tower’s height could not only be increased by larger base dimensions but also by increasing its column and panel dimensions, or combinations thereof. Finally, unlike steel, concrete is widely and locally available across the U.S., which leads to shorter transport routes and reduced costs. 

The project “Hexcrete Tower for Harvesting Wind Energy at Taller Hub Heights” (led by Iowa State University) was awarded $1.0 M by the Department of Energy, Office of Energy Efficiency & Renewable Energy.


“Acknowledgment: The information, data, or work presented herein was funded in part by the Office of Energy Efficiency and Renewable Energy (EERE), U.S. Department of Energy, under Award Number DE-EE0006737.”

“Disclaimer: The information, data, or work presented herein was funded in part by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference here in to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.”

Natasha Azar