What better way to test a wind turbine that needs to endure extreme conditions than by installing it on top of a telecommunications tower in Minnesota in the middle of winter? That’s exactly what Windstrip, a sustainable energy startup company in St. Paul, Minn., did. The past two Decembers, the company has placed prototypes of its Savonious-style wind turbine on the telecommunications tower at the Minnesota Department of Transportation.

Savonius wind turbines are a kind of vertical axis wind turbine named after the Finnish engineer who first created them in 1922. They feature curved blades that spin on a vertical rotor shaft and operate by cupping and dragging the wind, which turns the rotor and generates electricity. They do not have to be pointed into the wind and can “catch” wind from any direction.

Windstrip’s research and development team has worked with the University of St. Thomas in Minneapolis during the past four years to adjust the curvature of the turbine’s blades for use on radio, cell and other communication towers. The resulting turbines, which power the tower’s communications equipment, have been optimized for lower wind speeds and are 200 percent more efficient at generating electricity than basic Savonious wind turbines, according to Windstrip.

Most of the company’s wind turbines are part of a hybrid system that employs both wind turbines and solar panels to ensure a continual power supply. This means the turbines can be placed on communications towers just about anywhere – no matter what the weather conditions or how far off the electrical grid. Brian Plourde, COO of Windstrip, says the turbines are also a good fit for “brown” power areas with unreliable grids. Windstrip is currently working with numerous telecom companies to ameliorate power outages to their towers. International interest in the new turbines is high, according to Plourde, particularly from telecom companies in the Middle East, Africa and northeast Asia.

Regardless of where Windstrip systems are installed, the wind turbine’s design requires blades that are light enough to sit atop communications towers, yet durable enough to withstand damage from extreme temperatures, hail, ice, snow and blowing sand. That’s where composites enter the picture.

Plastics Unlimited Inc., Preston, Iowa, manufactures blades for Windstrip’s vertical axis wind turbines. The initial turbine specifications called for plastic, thermoformed parts. As the process evolved, however, it became clear that the blades would be lighter and more durable if they were made from composites. “We thermoformed the first blade and it wasn’t strong enough,” says Terry Kieffer, president of Plastics Unlimited. “Having a composite background, as well as a thermoforming background, it was just natural for us to go to composites right away.”