The arrangement can even make use of erratic airflow. "The turbulence is a potential benefit, as it draws in kinetic energy from above the [vertical turbine] farm," said Dabiri in an email.
Dabiri said that for large-scale power generation, the hurdles at this point are technical. "We need to demonstrate a cost-effective, reliable vertical axis wind turbine. It's a straightforward engineering challenge, but it hasn't been done yet," he said.
However, on smaller scales, vertical turbines have found a niche among home installers, which mount them on poles or rooftops. Some companies advertise their models as being bird-friendly. Sagrillo is skeptical of this trend. "There's no fuel where you're siting them," he said, pointing out that there often isn't enough wind to make these installations cost-effective at these scales.
He also said that vertical turbines are no safer for wildlife than propeller turbines. "A spinning rotor is a spinning rotor; it doesn't matter how it's oriented," he said.
Still, there are some applications where vertical axis turbines would be ideal, according to Veers. "When people look at very, very large offshore systems, the advantages of vertical axis become interesting again," he said. The advantage of having a lower generator and consequently a lower center of gravity helps lower installation costs on floating platforms in the ocean, where wind speed is typically higher than on land, observed Veers.
In the end, both vertical and horizontal turbines have their trade-offs, though horizontals are a more mature technology. "It's all a matter of the details and how well you have designed the machine," said Veers. "Either one can be an effective machine. In any size range, either one could be effective if you did it right."
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500