May 24, 2010

Ry Thompson
Seventh Generation Energy Systems

Alicia Leinberger
Seventh Generation Energy Systems

Canadian company’s first U.S. turbine spins plenty of power for cranberry farm

Dentist Frederick Prehn, owner of Prehn Cranberry Marsh near Tomah, wanted the power that the cranberry farm paid for without having to pay the utility.

“The second order of business, I wanted a turbine that has a history of working in low wind speed,” said Prehn.

A 35-kilowatt (kW) Canadian turbine, perched on a 140-foot-tall tower, accomplishes both. The first of its model line ever manufactured by Endurance Wind Power, Prehn’s wind generator underwent five months of testing at the company’s Quebec manufacturing facility.

“Wind speeds are all relative,” Prehn said. “The wind speed in the cranberry bog isn’t as good as the Great Lakes, but I’m amazed. I’ve gone through all the data I can gather, and the turbine is producing pretty well.”

“The Endurance fits Wisconsin’s climate conditions,” according to Ry Thompson, a project manager with Seventh Generation Energy, Madison, which installed the turbine.

“We’ve been eager to install one of these,” Thompson said. “It’s a very well-designed, durable machine and the 30-foot long blades make it suitable to lower wind speed environments, as are common in Wisconsin,” Thompson said.

“This should be a very popular turbine among farmers, schools, small municipalities, and manufacturing facilities,” he added.

The generator begins to produce electricity when the wind blows just under 8 miles per hour (mph). With an estimated average wind speed of 12.5 mph at his location, Prehn expects to harvest as much as 85,000 kilowatt hours of electricity – more than 150 percent of the amount he needs. The turbine powers a shop, three homes, and two wells. The excess energy is sold to the Oakdale Electric Cooperative, the farm’s local utility.

In addition, Seventh Generation installed a 5 kW solar electric system at the farm. “Some days the turbine produces goose eggs, and the solar system continues to crank out the electricity, and there’s no maintenance,” Prehn said.

“This is a shining example of home-grown energy,” stated Michael Vickerman, executive director of RENEW Wisconsin, a nonprofit advocate for all types of renewable energy.

“Installations like these help reduce Wisconsin’s dependence on coal from Wyoming which is transported here using oil from the Gulf of Mexico,” Vickerman said.

Prehn apparently agrees. He already has a contract with Seventh Generation to install a second Endurance turbine that will be slightly larger than the first.


RENEW Wisconsin ( is an independent, nonprofit 501(c)(3) organization that acts as a catalyst to advance a sustainable energy future through public policy and private sector initiatives.