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Published on June 12th, 2017 | By: April Gocha, PhD

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Taller concrete wind turbine towers may finally get off the ground to expand wind power potential

Published on June 12th, 2017 | By: April Gocha, PhD

[Image above] Credit: nate2b; Flickr CC BY-NC-ND 2.0

 

 

Almost 3.5 years ago, we reported on Ceramic Tech Today about an Iowa State University team that was developing taller wind turbine towers using a precast concrete technology called Hexcrete.

 

The Iowa State team had, at that time, just landed a $1 million investment from the DOE to develop the technology, and develop they did.

 

Then, in late 2015 we reported that the Iowa State team, led by Sri Sritharan, had completed some pretty intense tests of their high-performance concrete system. The team measured no damage in Hexcrete sections that were fatigue-tested for almost 200,000 load cycles—indicating that taller wind towers were becoming even more of a reality.

 

Fast forward to today, and things keep looking up for the Iowa State team.

 

But wait—why do the Iowa State researchers want wind turbines to tower even taller?

 

It all comes down to potential. According to studies of wind power potential from towers positioned 80 m off the ground—today’s current standard for wind turbine height—in comparison to towers positioned 140 m off the ground, there’s a big difference in potential that would make wind power viable in a much wider region of the United States (and more broadly, in the world) than is currently feasible. This graph nicely demonstrates that difference in potential.

 

Chart of the 48 contiguous states shows potential gigawatts of rated capacity above a given gross capacity factor (without losses) at heights of 80-m, 110-m, and 140-m above ground. Credit: US DOE

 

The reason is simple—at higher elevations, winds are stronger and more consistent, both pluses for energy generation from wind turbines. According to an Iowa State news release, Sritharan says that increasing the height of a wind turbine tower in Iowa by just 20 m can increase energy production by 10%.

 

To reach such great heights, however, wind towers must be really structurally sound to continue standing tall even when challenged with those strong winds—or else this may happen.

 

So Sritharan and the Iowa State team have been thoroughly vetting their Hexcrete system to make sure that it can stand up to the challenge of building taller towers. The system consists of precast panels of high-strength concrete that can be shipped to the site of installation, where they are bound together with cables into hexagonal cells that are stacked up to build towering wind towers.

 

Simulation showing how Hexcrete cells can be assembled and stacked on-site. Credit: Sri Sritharan; Iowa State

 

The researchers have continued testing their materials since our last report, and they say that even after 2 million cycles of pushing and pulling a test section of Hexcrete with 100,000 pounds of force, the high-strength concrete still passes the test.

 

“The testing was very successful,” Sritharan says in the news release. “The testing did show the system will work as we expected. There are no concerns about the cable connections or the concrete panels and columns.”

 

Testing setup for a full-sized Hexcrete cell. Credit: Iowa State

 

So, it seems that these taller concrete towers may really be getting off the ground soon—especially considering that the researchers also say that their technology will be cost-competitive. In fact, their calculations show that considering cost over the expected life of the taller towers brings their cost under that of the standard 80-m wind towers.

 

And considering the wider application area taller towers would enable, the winds may be shifting for renewable energy.

 

“Tall towers,” Sritharan says, “can add more capacity for renewable energy in all states across the nation.”

 


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