North Bay mills are part of U.S. wind energy boom

The McEvoy Ranch windmill south of Petaluma has a tower that is nearly 100 feet tall, with blades that reach an additional 40 feet toward the sky. (James Dunn / North Bay Business Journal) September 2017


Hurricane Irma, feared for her destructive personality, in an ugly category-5 mood two weeks ago snarled at 185 miles an hour, enough to topple trees, flatten houses and shove cars around on pavement. While fierce wind wields phenomenal power, wind energy makes up only about a quarter of one percent of a hurricane’s energy; the bulk is thermal energy released as rain. By the time Irma hurtled through Florida, she caused loss of electricity to some 60 percent of the state’s 20 million people.

Wind, with its dramatic role in storms, harnessed properly could generate more power than it takes away. The North Bay has significant investment in wind energy. McEvoy Ranch, which grows grapes and olives south of Petaluma, overcame neighbor resistance in 2009 to install a wind turbine that generates nearly a third of the electricity it needs. The lone turbine stands 147 feet tall on a hillside. It was the first windmill to power an agricultural facility in California, and the biggest windmill in Marin County.

Solano County turned its gusty microclimate to business advantage with several wind farms around Birds Landing, a hamlet about 17 miles from Fairfield. Shiloh Wind Power Plant, operated by Portland, Oregon-based Avangrid Renewables, completed its fourth phase in 2012 and cranks out more than 150 megawatts with 100 GE turbines sprawled over 6,800 acres of grazing land leased from ranches. Some of its turbines tower 260 feet with rotors spanning 253 feet. PG&E buys much of the power, along with the city of Palo Alto and Modesto Irrigation District.

Avangrid Renewables, which also markets power from High Winds Energy Center near Birds Landing, is a subsidiary of publicly traded Avangrid, a sustainable-energy company based in Connecticut with more than $30 billion in assets, revenue of $6 billion, 6,800 employees and operations in 26 states. The company in February 2017 reported that it expects some 9 percent compound annual growth in earnings per share by 2020.

Avangrid’s wind-farm capacity is nearly 5.8 billion watts from 54 wind farms in 19 states. A billion watts (1 gigawatt) is equivalent to about 4.6 million photovoltaic panels or 500 utility-scale wind turbines, and is enough to run more than 12,000 Nissan Leafs, which have 80-kilowatt motors.

“Renewables strives to lead the transformation of the U.S. energy industry to a competitive, clean energy future,” the company said in its 2016 annual report. Last year the company produced more than 14 million megawatt hours (14 terawatt hours) of energy from wind.

In the United States, wind generates more than 4 percent of total electricity. Iowa and South Dakota produce more than a quarter of their electricity from wind. The U.S. Department of Energy projected that the country could generate 20 percent of its electricity from wind with existing transmission infrastructure, and already has more than 81 gigawatts of installed capacity from wind. Wind energy is the fastest-growing source of energy in the world, according to the Wind Energy Foundation in Washington, D.C.

$16 billion new wind investment

In 2016, $13 billion was invested in U.S. wind turbines to add some 8,200 megawatts of new capacity. The country’s first offshore site was built last year near Rhode Island to generate 30 megawatts.

As a clean source of electricity, wind dovetails well with solar power, which works in clear weather. Wind energy thrives in stormy times when clouds block sunlight from reaching solar panels.

The McEvoy Ranch windmill near Petaluma was made by Norwin, based in Denmark. The 225-kilowatt turbine cuts in at wind speeds just under 8 miles an hour and cuts out when wind speed hits 56. The turbine can survive winds up to 125 miles an hour. The windmill weighs about 66,000 pounds.

The International Renewable Energy Agency estimates typical onshore power plants cost about $2,000 per kilowatt, but the McEvoy installation was far more.

“We had a lot of permitting issues” to get the windmill approved in Marin County, said Ria D’Aversa, director of ranch operations for McEvoy Ranch. Neighbors opposed the windmill for years. “It’s an eyesore” to some people, D’Aversa said. “We like them. They’re very pretty.”

June the best windy month

In June, the best month for wind generation at McEvoy Ranch, the windmill reaped 25,000 kilowatt hours. “It’s a really windy area,” D’Aversa said. “We don’t have solar. I’d love to get solar” as well.

“Summer is best for” wind generation, D’Aversa said, as wind-whipped fog charges inland during many afternoons. In an unusual year, the 2016 winter was extremely windy and yielded more power than usual. Winter months in most years produce less wind energy as rainstorms move slowly. “It depends on the year,” she said.

“Our founder Nan McEvoy wanted it,” D’Aversa said of the windmill. “They (neighbors on the east side of the ranch) fought it for a long time. People don’t want to see a wind farm. We only have one (turbine). I think it’s quite majestic.” To accommodate neighbors, the ranch moved the windmill’s site to the west, where it is visible from Red Hill Road but receives less wind.

Nan McEvoy bought the 550-acre dairy farm in 1990 and planted about 80 acres in olives. McEvoy died in 2015 and was granddaughter of M.H. de Young, who co-founded The Chronicle in San Francisco. A former reporter, McEvoy served as chair of the board of Chronicle Publishing, sold to Hearst Corp. in 1999.

EDF Renewable Services maintains the windmill, which produces nearly $20,000 worth of electricity every year. During times when the windmill produces more power than the ranch needs, extra electricity is sold to PG&E. “The way we spend our money here is set up for the windmill,” D’Aversa said. The grid “stores the energy for us and then we can use it. Our biggest two energy sucks are our olive mill and our winery. We don’t mill olives in June and July” when wind energy hits its peak. “We use it for all of our hospitality” operations, such as a retail store on the ranch.

Windswept Birds Landing

Avangrid Renewables markets power from windmills at windswept Birds Landing, an unincorporated community with population estimated at 150 located southeast of Fairfield, the county seat of Solano County. Windmill farms were established in Birds Landing more than a decade ago in a site called High Winds Energy Center. High-efficiency turbines swivel based on wind direction and can generate electricity even when wind slows to about eight miles an hour. Some manufacturers produce turbines with extra-long blades for extremely low wind conditions.

Florida-based FPL Energy owns High Winds. Turbines there were developed by Vestas Wind Systems, based in Denmark. Power is sold to Southern California Public Power Authority and other customers.

Florida Power & Light Company is the third-largest electric utility in the United States, serving nearly 10 million customers in about half of Florida, according to the company website. FPL is a subsidiary of NextEra Energy (NYSE: NEE), a clean-energy company with revenue of some $16 billion that also owns NextEra Energy Resources, which, “with its affiliated entities is the world’s largest generator of renewable energy from the wind and sun,” the FPL website said.

Sacramento Municipal Utility District has a wind farm in the Montezuma Hills near Rio Vista in Solano County. Developed initially in 1994, the farm had additional phases in 2006 and 2012. “It’s cost-effective,” SMUD said in its website describing the project. The community-owned electricity provider, which serves 1.4 million people and employs more than 2,000, obtains more than 20 percent of its energy from renewable resources.

Fuel costs zero

“By relying on the wind, fuel costs are zero, producing wind power at less than 5 cents per kilowatt hour. That makes wind power one of SMUD’s most economical resources,” SMUD said. “SMUD studies wind patterns and picks the best spots for turbines to take full advantage of winds that whip in from the coast. The site is one of the best locations in all of California for wind generation.”

As technology improves, wind turbines tend to increase in size. SMUD’s second-phase turbines were 415 feet tall, the tallest in the U.S. at the time. Offshore turbines have towers more than 260 feet high with massive blades about 325 feet in diameter. By 2030, towers could soar to more than 400 feet with blades up to 625 feet — twice the length of a football field — according to researchers from Lawrence Berkeley National Laboratory. Bigger turbine blades move more slowly, allowing birds to get out of the way.

By 2030, bigger turbines will have the capacity to generate 4 to 11 megawatts for offshore models.

Windmill for typhoons

Even though wind constitutes a tiny portion of a storm’s energy, a typical tropical cyclone could release some 1.5 terawatts of wind energy, scientists estimate. The world’s total electrical generating capacity is about 5.3 terawatts. Current turbines have blades designed to feather in extremely high winds so they don’t spin fast enough to burn out generators. To harness hurricanes, different turbine design would be needed.

Atsushi Shimizu, founder of Japan-based startup Challenergy, devised a turbine that resembles an egg beater with a trio of vertical rotating columns and blades tucked between platforms that can handle the punch of a typhoon. The design takes advantage of the Magnus force, where a spinning object in a flow of wind encounters a pulling force perpendicular to the flow. The force accounts for the curve of a spinning golf ball or tennis ball, as well as the break of a curveball in baseball. The force pushes the ball out of its main flight path.

In Shimizu’s patented turbine, cylinder rotation adjusts rapidly to sudden changes in wind speed and direction, allowing stable power generation even in strong winds. A typhoon in Japan can hit sustained winds of 73 to 97 miles per hour.

Shimizu obtained funding from New Energy and Industrial Technology Development Organization, which supports entrepreneurs. He also participated in Autodesk’s Entrepreneur Impact Program and used the company’s design software. Autodesk has headquarters in San Rafael.

James Dunn covers technology, biotech, law, the food industry, and banking and finance. Reach him at: or 707-521-4257