It’s not often that we get a chance to combine Warren Buffett with the topic of concrete wind turbine towers, so we pricked up our ears earlier this week when the legendary investor’s MidAmerican Energy Company announced that its new Iowa wind farm will include a 2.3 megawatt wind turbine perched atop a tower made of concrete. At 377 feet from ground to hub, the tower will top most conventional, steel-tube towers by more than 100 feet, easily making it the tallest in the US.
As wind energy fans know, all this racing to erect the tallest wind turbine tower isn’t just for bragging rights for the tallest er, tower. Winds are stronger and steadier at higher altitudes, ensuring a more reliable input while potentially reducing the cost of the electricity generated.
Why A Concrete Wind Turbine Tower
Before we get to that, let’s pause for an update on a separate collaboration between Siemens and Iowa State University with a financial assist from the Department of Energy, so group hug all you taxpayers.
CleanTechnica first caught wind of the project in 2013. At that time the typical steel wind turbine tower clocked in at about 80 meters, and the engineers at Iowa State set a relatively modest goal of increasing that by at least 20 meters, to achieve a wind turbine tower height of at least 100 meters.
We checked in on the project again in 2014, when we noted a couple of reasons why concrete makes sense for wind turbine towers in some situations, despite the issue of carbon emissions related to cement production (cement is a component of concrete).
The US has a thriving domestic concrete industry and Iowa also has a strong homegrown cement industry, which would reduce shipping costs and shipping emissions for turbine towers. More to the point, concrete wind turbine towers can be assembled on site from relatively small components.
In contrast, each section of a tubular steel tower needs to fit in, over, and around existing bridges, tunnels and other infrastructure. With the size of the lowermost section limited, the ripple effect is to limit the height of the tower to — you guessed it — about 80 meters.
Why A Hexcrete Wind Turbine Tower
As one of the world’s top wind turbine manufacturers, Siemens is naturally interested in something bigger and better upon which to park its bigger, better wind turbines, so the partnership with Iowa State is a natural. As described by Siemens, the mission of the “Hexcrete Tower for Harvesting Wind Energy at Taller Hub Heights” collaboration 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.
Siemens has considered steel components with vertical instead of horizontal seams, but determined that in light of the engineering and quality control factors, the potential payoff for concrete was more attractive.
The company’s Wind Power and Renewables division has provided an assist in the form of 3D modeling, and other support aimed at coming up with a cost-effective design. “Hexcrete” refers to the tower sections, consisting of concrete panels and columns hooked together by cables to form hexagons.
Iowa State updated the wind turbine tower project just last week with news that cross sections of the tower have been sailing through their stress tests.
Here’s a rundown on the funding from Iowa State:
Current research and development of the Hexcrete towers is supported by an 18-month, $1 million grant from the U.S. Department of Energy, a grant of $83,500 from the Iowa Energy Center and $22,500 of in-kind contributions from Lafarge North America Inc. of Calgary, Alberta, Canada. The project’s industry partners also include the Siemens Corp.’s Corporate Technology center in Princeton, New Jersey; Coreslab Structures (OMAHA) Inc. of Bellevue, Nebraska; and BergerABAM of Federal Way, Washington.
A Concrete Wind Turbine Tower For Iowa
Now for the Warren Buffett connection. It looks like MidAmerican Energy is confident enough about the concept to engage Siemens for constructing the new concrete wind turbine tower on a prototype basis, as part of the 64-turbine, 154-megawatt Adams wind farm now under construction.
Completion of the wind farm is expected by the end of this year so we’ll be sure keep watch for any updates once the blades start spinning.
Consistent with the overall goal of the project, both the concrete work and the turbine blades are coming from Iowa manufacturers, with the blades from Siemens’s own factory in Fort Adams.
Thanks to MidAmerican, the Fort Adams factory lays claim to the world’s largest single order of wind turbines, a 448-unit behemoth put in back in 2013, as part of the company’s $1.billion wind energy investment in Iowa.
The timing of the massive order was perfect. In 2012 the factory had to lay off hundreds of workers partly due to uncertainty over extension of the federal Production Tax Credit for wind, but the credit was restored in 2013 (thanks, Terry!) and things seem to be humming along with the MidAmerican order.
So…what was all that fuss about “losing” Keystone XL pipeline jobs?
Photo credit: “Hexacrete” wind turbine tower section testing via Iowa State University.
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