A new analysis of installing and operating a donated wind turbine on Tybee indicates it wouldn’t be as beneficial as first described.
Tybee council member Paul Wolff has removed the proposal from the Feb. 27 city council agenda.
“After digging a little deeper into the economics, the wind speed was lower and the offset power rate was lower,” said Wolff, who had championed the idea. “Had one remained constant it would still have been viable. Since both dropped it didn’t make economic sense to go forward.”
The turbine, an Endurance E-3120 model valued at $272,000, was offered to Tybee from an undisclosed corporate donor. Plans called for it be sited next to the water treatment plant on Tybee’s north end so it could directly power that facility, which is Tybee’s single biggest electric bill. Attached to a 120-foot monopole with its three blades’ sweep reaching a maximum height of 150 feet, the turbine is about as tall as the nearby cell tower, water tower and lighthouse.
Taking into account an estimated $134,000 in shipping and installation costs, initial estimates of the long-term benefits to Tybee valued the gift at about $400,000 over 20 years. But those numbers didn’t hold up to scrutiny.
Wolff had initially valued the electricity produced at 14 cents per killowatt hour based on the “low-end average” of the rates Tybee pays across its facilities. But for the water treatment plant, which operates around the clock, Tybee has a time-of-use agreement with Georgia Power that reduces its rate there to 7.52 cents per kilowatt hour.
“That’s a 46 percent reduction in avoided cost,” Wolff said.
Lowered wind estimates
And then there’s wind speed.
Consultants from Wind Turbines of South Carolina, which installs turbines, calculated average wind speed at 15.2 mph. That speed would generate about 200,000 kilowatt hours per year, Wolff said. However, their analysis factored in gusts, which a subsequent analysis by council member Bill Garbett removed. Garbett, who had researched the feasibility of wind turbines on Tybee several years ago when the issue was first raised for Memorial Park, said the consultants’ data looked wrong to him. He looked anew at the issue, gathering data from National Renewable Energy Laboratory, the NOAA weather station at Fort Pulaski and an anemometer located at the North Beach Parking Lot, and came up with a likely wind speed of 11.2 mph.
“Some have told me that this is an opportunity to showcase the potential of wind power in this region,” Garbett wrote in a report on his findings. “Unfortunately, the data shows just the opposite.”
The wind speed Garbett estimated sounds about right to Simon Mahan, renewable energy manager for the Southern Alliance for Clean Energy, a nonprofit that advocates for wind energy.
“Take the best resources and if you cobble them together then 5 to 5.5 meters per second (11.2 to 12.3 mph) is a reasonable range for this hub height,” he said.
Pro bono analysis
While Garbett was researching wind speeds and Wolff was researching the electricity rate, Tybee native Charles Adkins volunteered his services to analyze the whole picture.
Adkins, who lives on Wilmington Island, is vice president of Ventyx LLC, which helps utility companies make decisions about building power plants.
He was skeptical when he first learned of the turbine.
“My first response was they’ll never be able to do that,” he said. “When I heard it was donated that changed my mind.”
He offered to do a more robust economic analysis free of charge, plugging in the new data as it became available. Even with the lower avoided cost on electricity, the deal looked doable at the original wind estimate.
“If the average wind speed is greater than 14 mph that unit would be able to justify itself on avoided costs to Georgia Power,” he said.
When the wind speed estimate dropped to 11.2 mph, Adkins factored in “soft benefits,” including the salvage value and federal production tax credits, but even that couldn’t make it worthwhile. In that scenario Tybee was looking at losing up to about $40,000 over the life of the project.
“The break even was too big,” Adkins said.
At odds over birds
Previously, the biggest obstacle to the turbine was a concern over threatened and endangered shore birds, including red knots and piping plovers. A Georgia Department of Natural Resources wildlife biologist weighed in against the turbine’s planned siting at a recent public meeting.
“If I look at the overall map of Tybee, this is the last place I’d put it,” Tim Keyes said at the Jan. 27 town hall meeting.
Just last week, however, the Coastal group of the Georgia Chapter of the Sierra Club recommended that Tybee not impede or delay the installation of the turbine because of concerns over birds.
Among the reasons they cite are the turbine’s relatively small size, its monopole construction and the fact that with one exception “available documentation shows that the birds of most concern, (red knots and, particularly, the piping plover), are rarely seen at this location, and when seen are present in very small numbers.”
Wolff said he still thinks the project would be beneficial, even if it wasn’t a moneymaker.
“It would offset greenhouse gas emissions; it would be a pioneer in the Southeast in terms of coastal wind installations,” Wolff said. “And it would give the possibility of developing a pilot study of how one small turbine in a sensitive area impacts wildlife.”
But he’s ready to give up the fight. Other sites have been rejected as too close to houses or lacking in wind. And without Garbett’s vote, the proposal is a “dead duck,” he said. Wolff expected to call the corporate donor, which has remained unnamed at its request to avoid negative publicity, and decline the offer Tuesday.
“As a public official I cannot impose that kind of risk on taxpayers,” Wolff said. “There are too many variables to depend on an economic benefit. Absent that benefit I don’t think it’s a viable project in terms of overall benefit to the community.”