Iowa Wind and Siemens IP

Iowa is receiving significant new investments in wind energy thanks to MidAmerican Energy’s record-setting 448 ordered turbines in December 2013 and Caroll Area Wind Farm LLC’s 9 ordered turbines in May 2014. These investments mean Iowa’s wind energy production should increase and grab more of a share in the composition of Iowa’s total power generation from an already impressive 24% stake in 2012.

Wind turbines on a farm,

Both of these orders were for wind turbines from Siemens Energy Sector, a division of Siemens AG. The orders call for 2.3 megawatt (MW) turbines with rotor diameters of 108 meters, where each blade is 53 meters long. This diameter and blade length creates a “swept area” of 9,150 square meters. Once produced, the blades will not need to travel very far because they will be manufactured at Siemens’ production facility in Fort Madison, Iowa.

Each order is for Siemens SWT-2.3–108 wind turbines. Siemens describes the turbines as providing “[e]xtra energy output in low to moderate wind conditions.” More interesting for the purpose of this post, the turbines use Siemens B53 quantum blades with an innovative blade design. The design incorporates Siemens aeroelastically tailored blade (“ATB”) technology.

Close-up of B53 blades,

The B53 blades have a unique shape because of their use of the ATB technology. Siemens provides a simple illustration of what a traditional blade looks like compared to an aeroelastically tailored blade. The ATB technology adds length to the blade and introduces curvature to the end of the blade. Siemens explains the curvature allows the blades to not only bend, but also twist. The company designed the twisting to improve wind load management by increasing the blade’s ability to flex and redistribute force. The benefit of improved management capabilities is a decreased rate of blade fatigue and, correspondingly, an increased service life.

Blade comparison from Siemens marketing materials
ATB technology description from Siemens’ Living Energy magazine

The uniqueness of the blades immediately raises questions whether the ATB technology is protected by any patents. Siemens is one of the largest patent owners in the world and they have thousands of U.S. patents. Learning what patent applications might cover the blade technology takes some digging, but traces of protection efforts pop up.

Siemens applied for a patent to a “Method of Modifying the Surface Shape of Wind Turbine Rotor Blade and Tool for Use in this Method” under application 13/490,575 (the ‘575 Application). The application was published December 13, 2012 under the publication number US 2012/0313291. The application is currently under its first final rejection from the USPTO, posted August 14, 2014.

The ‘575 Application appears to describe the curvature incorporated into the aeroelastically tailored blades. The application explains that modifications to blade shapes are usually for alteration to aerodynamic properties. Perhaps strategically, the ‘575 Application does not elaborate on what aerodynamic properties the method is intended to alter. Nevertheless, the ‘575 Application figures show a curved end to a rotor blade through the casting of a “shape modifying element”.

Cover figure to U.S. Patent Publication 2012/0313291 (the ‘575 Application)
Figures 1–3 to U.S. Patent Publication 2012/0313291 (the ‘575 Application)

The casting described in the ‘575 Application is meant to create a “seamless or almost seamless connection of [the] shape modifying element to the surface of the wind turbine rotor blade.” A liquid resin is applied to the shape modifying element’s inner mould surface and the resin is cured to bond the element to the surface of the rotor blade. The seamless connection is likely important for functional and branding purposes. Functionally, a seamless connection means there won’t be undue drag that would affect the aerodynamics and aesthetics of the blade. With respect to branding, Siemens has an IntegralBlade® mark to describe its blade casting process that relies on patented technologies.

Assuming the ‘575 Application represents an important part of the ATB technology, it is interesting that Siemens would deploy the new blade designs in the U.S. before securing a patent under the application. It is feasible other patented techniques address the ability to cast its blades with greater curvature than traditional blades. In fact, Siemens has a whole series of patents with regard to shaping a blade. The U.S. patents include:

  • US 7,980,840 — Mould and method for vacuum assisted resin transfer moulding
  • US 8,007,624 — Method of manufacturing wind turbine blades comprising composite materials
  • US 8,079,818 — Method for manufacturing of a fibre reinforced laminate, use of a wrinkle-preventing material, wind turbine blade and wind turbine
  • US 8,191,255 — Method for manufacturing wind turbine blade with an integrated lightning conductor
  • US 8,202,454 — Mould and method for vacuum assisted resin transfer moulding
  • U.S. 8,282,874 — Method for manufacturing a composite and a wind turbine blade
  • U.S. 8,647,545 — Method to manufacture at least a component of a blade of a wind-turbine
  • U.S. 8,656,627 — Determining a distribution of multiple layers of a composite material within a structural volume

The list of patented moulding methods and techniques is extensive, but none include figures that would suggest a curved blade tip that signifies ATB technology. Siemens began production using ATB technology in 2012, twelve years after IntegralBlade® technology first arrived. Incremental improvements in casting may have led to increased abilities to incorporate curvature into a blade’s tip. In the ‘575 Application’s favor, though, is that Siemens introduced the ATB technology just one year removed from the ‘575 Application’s earliest priority date. Thus, it is not unreasonable to think the ‘575 Application is correlated with the ATB technology.

More in-depth analysis would likely pin down which patents and applications cover ATB technology. For now, I think it is exciting to see Iowa on the forefront of wind energy and a beneficiary of a major patent player’s intellectual property.

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