Advantages of Composite Space Frame Wind Turbine Towers for Smaller Farms, Greater Heights, and Increased Capacities

70465B02-II By definition, wind shear creates substantially higher winds at greater heights; therefore in many parts of the U.S., wind sites that are marginal at lower heights could become viable at greater heights. The additional reliability of these winds increases turbine utilization, enabling more economical energy production. However, the high cost of construction, shipment, and installation of large and heavy towers to support these turbines increases the cost of energy and marginalizes the economics. Presently, 1.5 MW turbines are rarely taller than 80 m because of this limitation, and many sites are left undeveloped. This project will develop a lightweight, space frame tower made of carbon that will be assembled at the job site to enable easy tilt-up, thereby eliminating the need for an expensive crane and keeping transportation costs low. Phase I used computerized optimization routines to analyze over 70 geometries for a 1.5 MW tower at heights from 63 to 100 m. A lightweight, composite tower configuration was identified that not only would have lower manufacturing costs, but also would be able to withstand wind turbine loads and tilt-up stresses at greater heights. Phase II will assemble space frames from composite tube segments. A detailed design will focus on the interface between the metal and the composite tubing. Strength and fatigue testing will be conducted to verify the integrity of the joints and the composite tubes. Upon completion, a 1.5 MW turbine using a space frame tower will be erected. Commercial Applications and Other Benefits as described by awardee: By eliminating the need for expensive, large cranes and overly heavy, transport-limited steel tubes, a tilt-up space frame tower should enable economical wind turbine installations at greater heights, on smaller farms, and on rougher terrain.