Perched on 40-foot towers, two Bergey Excel turbines began their work today (Sept. 22), turning the wind into watts for Harvard’s electrical grid.

The twin turbines, each rated at 10 kilowatt-hours, represent the University’s largest wind energy project on campus to date. They dwarf the six turbines perched at the edge of a roof on the Holyoke Center — units the height of a man that are rated at just 1 kwh each.

The turbines, sited on the roof of Harvard’s Soldiers Field Parking Garage, are tucked into bullet-shaped housings of red Fiberglas and steered into the wind by wide red tails. They will provide more than supplementary power for the garage, said James W. Gray, associate vice president of Harvard Real Estate Services (HRES). “They expand the outward statement of sustainability that wind energy provides.”

The spinning turbines, fitted with white Fiberglas blades that sweep 23-foot arcs in the air, are visible from the Massachusetts Turnpike, from Western Avenue, and from points within Harvard’s Cambridge campus.

HRES owns a share of the parking garage, which is next to Harvard graduate housing called One Western Avenue. Gray also gave credit for the wind project to John Nolan, director of Harvard University Transportation Services, which owns the other share.

The idea of the new turbines originated with Joseph Gregory, assistant director of sustainability at HRES. “Wind power is intermittent,” he said, “so I thought the cars at the parking garage wouldn’t complain.”

The installation was preceded by three years of work: a year of wind tests, a year of wrangling permits, and a year of site design and preparation work. Construction began early this summer.

The turbines each weigh more than 1,000 pounds and are riveted to 1-ton, free-standing steel towers. Getting that much weight and height in place on the roof of a parking garage took some extra engineering. So the towers rest on tubular steel bases that extend two stories below the garage roof.

One of the two towers was already tipped into place and bolted down this week (Sept. 21) when installer Thomas Dowd took a break to explain how the turbines work. He’s owner of North Shore Solar and Wind Power of Beverly, Mass.

“No one’s put these on parking garages before,” said Dowd, standing by the second tower, which leaned on heavy wooden pallets, ready for lifting. “Harvard is the first one to do it.”

Dowd, wearing a white hard hat with “Boss” scrawled on the front, opened an access door on the turbine housing. Inside was a large alternator that creates DC (direct current) power when the big blades turn in the wind.

The DC power then zips through a thick black cable, down the barrel-size towers, and through three 60-amp fuses. In a basement electricity room, an inverter flips the DC power to AC (alternating current), which in turn feeds right into the Harvard power grid.

As it happens, energy efficiency at the garage got a recent boost from more than the two dramatic wind turbines. The 800-space, six-story facility was part of a recent $2 million retrofit of garage lighting at Harvard.

Now in place are vapor-tight Super T8 fixtures that are long-lasting, low-mercury, and high-efficiency. Early data shows that the new lighting will create a 40 percent savings in energy costs, said Jenny Harvey, program coordinator for sustainability at HRES.

“Because of the efficiency of the lighting,” added Gray, “the wind goes a lot further.”

“You have a confluence of events here,” agreed Heather Henriksen, director of Harvard’s Office for Sustainability, who along with Gray took in Monday’s rooftop lesson in wind power.

HRES is a leader at Harvard in “on-site renewable energy generation,” she said. “This project is a tremendous test case as we move toward achieving our greenhouse gas reduction goal.”

Last year, Harvard President Drew Faust announced a pledge that the University would reduce its greenhouse gas emissions 30 percent by 2016, with 2006 as a baseline year.

HRES now has two wind generation projects in place — both “experimental,” said Gray, as Harvard explores the efficacy of renewable power sources. But the Soldiers Field turbines, he said, were a step forward both in scale and in versatility.

The small turbines on the Holyoke Center roof have a limited capacity to pivot into optimal winds. But the newer, bigger turbines — though mostly orientated to prevailing winds from the southeast — can rotate 360 degrees in a hunt for maximal wind currents.

While turning even in high winds, said Dowd, the Soldiers Field turbines will create only 32 decibels of sound — about the same as an average rooftop air conditioning unit.

Counting the height of the brick garage, the new turbines are about 120 feet in the air, well below the 200-foot limit set by federal authorities for required tower lighting.

Part of the height “is a statement,” said Lee E. Phelps regarding the turbines’ visibility to Harvard and its neighbors. He’s assistant vice president at Jones Lang LaSalle, the construction firm that consulted with HRES on the wind project, and on its rooftop solar hot water projects, too.

The rooftop turbines are a simple, durable design that’s been around for decades, said Jones Lang LaSalle senior project manager Chris Packard, who oversaw the installation phase of the project.

“You get them up,” he said of the tower-mounted turbines, “you connect them to the power grid, and you walk away.”

To Henriksen, the new wind turbines are part of Harvard’s living laboratory in sustainability.

Even more, said Gray, “They make a difference right away.”

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