MARIN COUNTY – In a step back hundreds of years when most food mills were powered by the wind, fine olive-oil producer McEvoy Ranch has erected the first windmill of its size in California to be put to agricultural use. According to company agroecologist Jeff Creque, the windmill is the first step toward producing all of the ranch’s power onsite. “The windmill will cover our electricity needs, and we’ll be installing a solar thermal water system to replace propane-powered turbines for heat,” he said. “I told the cooks they could keep their gas range, though.”
What with picking operations, milling and some bottling, electricity use at the ranch is about 225 kilowatts a year.
The 225 kilowatt windmill was designed and constructed in Denmark, where working windmills still dot the countryside.
McEvoy Ranch conducted a three-year wind study before deciding on its type and placement. “People generally think of west Marin as always windy, but it doesn’t compare to passes and deserts where you usually see wind farms,” said Mr. Creque.
The McEvoy Ranch was deemed to have “adequate wind,” enough to power a windmill about one third of the time. So a relatively small turbine was chosen. But still, unlike solar panels, the 140-foot windmill is a major presence in the landscape, and the McEvoys encountered major hurdles to installing it.
Marin County was forced to update its wind ordinance, drafted during the 1970s and never foreseeing the range of wind-capturing technologies now coming to market.
Neighbors objected to the site, the size and the tower design. “We re-drafted, re-scaled and relocated the windmill until all the neighbors’ concerns were met. The Marin supervisors wouldn’t give us their nod of approval until we did,” said Mr. Creque.
Of major concern was the deadly effect windmills appear to have on wild birds, especially raptors. The bad rap is largely the result of the wind farm at Altamont Pass, an installation today’s wind advocates say should never have been built.
Not only is Altamont on a migratory path, its abundant ground squirrel and other rodent population makes it a favorite habitat of raptors. The lattice-like towers that support the Altamont mills provided attractive perches for raptors.
“And added to all that, the choice of ultra-fast turbines was a disaster,” said Mr. Creque. The McEvoy turbine, like most produced these days, is much slower but just as powerful due to improved torque.
“It’s very unlikely that a bird wouldn’t see the blades. And we checked migratory and feeding patterns of both birds and bats to make sure we weren’t in their path,” he said.
The conclusion was that a single turbine, moving relatively slowly when it moved at all, didn’t pose a significant threat. Still, the ranch has committed itself to an ongoing bird and bat mortality study.
The project has aroused lots of curiosity among farmers in the region, Mr. Creque said, who might be interested in similar wind technology if the McEvoy system proves out.