Following congressional passage in December of a multiyear extension of the wind-energy production tax credit and investment tax credit, the wind industry is breezing ahead with a new lease on life. In December, the American Wind Energy Association also cheered passing the 70,000-MW milestone of total installed wind-energy capacity. The industry’s expansion is not only horizontal, spreading out across the landscape, but vertical, too, as engineers strive for ever-greater hub heights for towers supporting ever-larger nacelles.
Typical hub heights for U.S. wind towers are about 80 meters, engineers say. MidAmerican Energy has claimed a 115-m tower of stacked concrete segments, erected last fall in Ames County, Iowa, is the tallest in the U.S. Now, an Iowa State University engineering professor is preparing to explore commercialization of a concrete tower designed to reach 140 m tall, hosting a workshop in Denver for developers, contractors, crane companies and others.