Lattice IsoTruss Structure for Wind Turbine Towers

Lead:

IsoTruss

Partners:

TPI Composites & University of Tennessee, Knoxville

% cost share:

IACMI: 68%
Industry: 32%

Duration:

October 2022 – October 2023

Problem statement:

Typical wind turbine towers are tubular steel, tubular concrete, steel lattice or steel guyed structures. Steel and concrete towers are heavy, use carbon-intensive materials, and are subject to corrosion especially in humid areas or offshore turbines.

Project goal:

To explore innovative solutions to make wind blades larger, lighter, and more efficient by exploring composites in the support tower for turbines.

Technical approach:

Four tower solutions were designed and fabricated to test and match stiffness and torsional rigidity: steel, carbon fiber, IsoTruss monopole, and a Modular IsoTruss solution. The Modular design used 40-inch diameter, 20-foot long sections with a maximum of 1-inch diameter for any member. Two types of connections were used in the Modular design: longitudinal-longitudinal and longitudinal-helical connections. Longitudinal members were vertical or axial members, while helical members were diagonal and horizontal members. The number of Modular IsoTruss sections used, the placement of the sections, and the diameter of the base were optimized to reduce weight while meeting performance requirements.

Conclusions:

• Composites show promise in infrastructure applications such as wind turbine towers because of installation savings and corrosion resistance.
• Composite solutions can (and should be) unique to take advantage of their unique capabilities. For example, a modular IsoTruss solution is more advantageous than a monopole solution and feasible because of the IsoTruss sections are so lightweight.
• To be competitive, any composites solution should aim to be close to parity with current steel solutions. Although the material cost is higher, cost savings come in using less material and easier transportation and installation.

Recognition:

Received the JEC Composites Innovation Award at JEC World 2023

Potential impact:

• Replacing steel or concrete wind turbine towers with composite lattice IsoTruss towers will reduce material, make installation easier, and increase the lifetime.
• The IsoTruss geometry optimizes the placement of fibers in the composite to align with the loading which allows material savings of up to 12X compared to steel structures.
• The material savings result in a weight and cost savings as well, with the structures being much more easily maneuverable and requiring less heavy machinery for installation and delivery. Customers have estimated installation cost savings of 60% with IsoTruss towers compared to steel towers.
• The corrosion resistance of composites also has significant impacts for product lifetime, especially in humid or coastal environments. One IsoTruss telecom tower customer stated that steel towers can corrode after 5 years in extreme environments where composite towers are rated to last more than 50.