April 21, 2009
-- Greenward Technologies, Inc. announced today that it has added patent pending ISO-e tower technology to its growing wind energy technology portfolio.
According to Ed Salter, the company's CTO, “ISO-e is a revolutionary new tower design and manufacturing process that will reduce the structural steel content by at least 50%, resulting in a large decrease in manufacturing cost, and should make the tower virtually ‘typhoon-proof’
The company provided the following additional information:
The two primary issues addressed by this technology are the costs associated with the very large steel content of wind turbine towers and their vulnerability to buckling failure in very high winds. Buckling starts as elastic instability of the downwind side that is loaded in compression and can progress rapidly to catastrophic failure. The new design utilizes a much thinner steel inner shell, combined with an outer jacket of a proprietary concrete and polymer composite that is 6 ½ times as thick as the steel shell. This is applied over the outside of the pressurized steel shell and a steel reinforcement system using the “Shotcrete”
process. Once the outer jacket has cured, the pressure is slowly released and its stored strain energy becomes optimally distributed between the shell and the jacket. The name ISO-e alludes to this equal-but-opposite shared strain energy, which acts to increase the tower's resistance to buckling in the same way that pressurizing any tube has a similar effect, while ensuring that the concrete composite jacket never experiences any tensile stress. The ISO-e tower weighs about the same as a similar, all-steel tower.
Salter further stated that “In addition to providing solutions to critical issues currently faced by manufacturers, insurers, and wind energy developers, the technology offers a number of other benefits as well. The completed tower demonstrates a much higher damping ratio than conventional all-steel construction in addition to its greatly increased buckling strength. This reduces tower sway and provides for large reductions in radiated noise levels. In addition, a thin, chloride-resistant outer layer may be applied to towers destined for offshore or near-shore installations, and the outside may be colored to match the environment, providing a more pleasing appearance. ISO-e results in higher performance and more attractive towers at a much lower cost.”
The company is currently seeking qualified tower manufacturers to license this technology.
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Greenward Technologies is an “incubator”
for the most promising renewable energy solutions. We advance current and emerging technologies from concept to reality. Our initial focus is on wind energy with an innovative new turbine design.