Windmills in Cambridge?

Wind turbines, it seems, are popping up more and more across the country’s landscape.

So why not put one in Danehy Park?

That’s the proposal being floated by one city councilor who says Cambridge needs to get innovative if it’s going to reach its goal of being 20 percent "green" by 2010.

"I think a lot of people are going around saying, ’Why don’t we have [a wind turbine] at Danehy Park?’" said Councilor Henrietta Davis, who sponsored a motion to explore the idea last month. "It seems like an obvious idea."

In terms of land mass, Danehy Park may be one of the more open, open spaces in the city. But green energy experts are questioning the effectiveness of a turbine anywhere in Cambridge, saying the city lacks a crucial ingredient: wind.

"Cambridge probably has two challenges to a large-scale turbine," said Warren Leon, the director of the Renewable Energy Trust at the Massachusetts Technology Collaborative. "One is wind. Second is land. As a densely populated place with not a lot of open space, it makes it harder."

City officials are now exploring the wind turbine’s feasibility for a May 2 meeting.

But Davis said the wind turbine is only one idea. At a meeting on March 7, officials and energy experts said Cambridge might reach its 20 percent goal quicker by investing more heavily in green power produced elsewhere.

With a turbine, the city would have to contend with both a lack of wind and neighbors in Neighborhood 9 who might not want a 250-foot windmill in their back yard.

"I do wonder if we are going to be a place that really steps up to the plate and says, ’Yes, we need a different source of energy than oil’ and how people are going to grapple with that ... I hope we’re not all NIMBY people," said Davis.

NIMBY stands for "not in my back yard."

More than 25 communities in the state are eyeing turbines of their town, said Leon. Hull already has one up and running and is installing a second. The International Brotherhood of Electrical Workers erected a 150-foot-tall turbine outside its headquarters in Dorchester that works to power the building.

According to the MTC, an ideal location for a turbine should have an average wind speed of about 14.5 miles per hour. Wind maps put average gusts in Cambridge around 12 to 13 mph. Hull winds, by comparison, blow around 16 mph.

While Cambridge may seem close, John Dunlop, an engineer for the American Wind Energy Association, said slight increases in wind speed produce big results on a turbine. A turbine in a town with 13-mph winds could make 30 to 50 percent more electricity than a turbine in a town with 12-mph winds.

Elevation is also a factor. Jeff Amero of the city’s Geographic Information System department said Danehy Park’s elevation is only 48 feet, lower than the city’s high point of 80 feet in Avon Hill.

"But [Danehy Park is] higher in comparison to areas around it," Amero said in a voicemail. New Street, for example, is only 5 feet above sea level.

City buildings consume about 42 million kilowatt hours of electricity per year, according to George Fernandes, the city’s electrician. Currently, about 3.5 percent of this amount comes from a green source, one being solar panels on the City Hall Annex building.

One way of increasing this share is to invest in wind or solar power produced elsewhere, something Cambridge does now.

When wind energy is produced, it can be put onto the New England power grid and become part of the energy mix. Wind energy manufacturers can then sell vouchers, called Renewable Energy Certificates, for units of that energy to other municipalities. Those who purchase the certificates help support the share of renewable energy and can take credit for being green.

"What we’re trying to do with certificates is level the playing field," said Larry Chretien, the executive director of the Mass Energy Consumer Alliance. "So that wind power gets a chance in the marketplace."

Wind power and turbines are also still expensive. Depending on the size, a turbine can cost more than $1 million. Cambridge now pays slightly under $30,000 for every 1 percent of green energy it buys elsewhere. And while wind turbines in windy places can take up to seven years before they make money for a city, one estimate for Cambridge put that figure at 13 years.

Deputy City Manager Rich Rossi said the city will explore Danehy Park along with other ideas for generating green energy. Already, though, there are some preliminary concerns. "In a dump site, you don’t just start digging holes," he said. "There are issues with materials buried there."

Danehy Park is built on top of a former city landfill.

For parents who might be worried about kids playing near a turbine, Leon said for the most part they’re safe. It’s theoretical that a blade could fall off one, but he’s yet to hear of it.

"One issue sometimes has to do ... with ice forming on the blades during a storm and falling off right below," he said. "But there are ways to address it. Either turn off the machine or don’t sit below it during an ice storm."