SBIR Phase II: Optimization of Tapered Spiral Welding for Wind Turbine Towers

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This Small Business Innovation Research (SBIR) Phase II project addresses two roadblocks to reducing the cost of wind energy: the labor-intensive construction process, and size limitations imposed by road or rail transport for turbine components. The former issue drives up manufacturing costs and reduces US competitiveness with countries with inexpensive labor, while the latter forces sub-optimized tower designs and prevents turbines from growing larger and taking advantage of faster, steadier winds at higher hub heights. This project addresses both of these problems by adapting spiral welding - a well-understood system for pipe and piling manufacturing - to wind tower production. Spiral welding is highly automated, requiring as little as 10% of the labor of the equivalent manual process. It also combines multiple operations into a single machine that can be operated on-site, eliminating transport costs and barriers. This project's innovation is to adapt existing spiral welders -that can manufacture only straight,constant wall-thickness pipe - to producing tapered, variable wall thickness towers. A novel material geometry and automated control of machine parameters are the keys to transforming the standard system to one optimized for turbine tower production. With on-site spiral welding of turbine towers, significant reductions in cost of wind energy are possible.The broader impact/commercial potential of this project will be felt in many areas: technical,commercial and environmental. The system's major contribution is an increase in the use of wind energy for US electricity, enabled by both reduction in energy cost and increase in the number of cost-effective wind sites. Reducing the cost of tall towers enables increases in the height and size of wind turbines, allowing them to reach and be optimized for steadier, higher speed winds. With these increase in size and optimization, decreases in cost of wind energy of 12% (for 120m tall towers) or more are possible. In addition, the US land area for which wind energy is cost effective can be doubled at 120m hub heights. Spiral-welding of turbine towers also provides US jobs and increases American competitiveness with overseas producers. Because on-site production is inherently local, manufacturing jobs are created in the communities where wind turbines are installed. Also, this method gives local production a major cost advantage over imports by producing towers that are too large to transport from port to wind farm. This allows domestic manufacturing to not only compete, but dominate in a domestic tower market worth roughly $1B in 2011.