Illustration provided by Robert Torres / TAM Energy

The wind turbines that North Charleston is considering measure 6 feet in diameter and weigh 185 pounds. They could save the city an estimated $4,500 to $5,000 a year in energy costs.

North Charleston City Council took the first step toward putting energy-producing wind turbines on the roof of City Hall, but one hurdle could be what the building's air-conditioning provider thinks.

City leaders want to put five wind turbines on the roof where they will capture the exhaust breezes coming off the building's cooling system. As the turbines turn, the blades will harness breeze energy to be recycled and carried back inside and used as electricity.

But Trane, the manufacturer of City Hall's air-conditioning units, wants to check to see if the turbines affect performance or put pressure back on the exhaust.

Even if there is a problem, city leaders said they plan to put the turbines on the roof to run on natural wind. "This is where everybody is headed," said Mayor Keith Summey, advocating the move toward green technology.

The turbine systems are manufactured by TAM Energy of North Charleston, a small business that operates in Stark Industrial Park off Azalea Drive. The facility has no connection to Clemson University's nearby wind-turbine testing facility at the former Charleston Naval Base.

In the TAM system, each turbine is about 6 feet in diameter and weighs 185 pounds.

To be able to turn, the turbines use a system of magnets and stators surrounding an outer ring that act to capture power at the blade tips -- where speed is greatest -- to eliminate mechanical resistance and drag.

City Council's Finance Committee on Thursday approved a no-bid contract of about $57,000 to install the units, with the money coming from a federal grant.

One estimate is that the cost savings of using the turbines could knock about $4,500 to $5,000 a year in charges coming off City Hall's annual power bill.

The turbines' manufacturer said the project has national implications because North Charleston City Hall would be the first municipal building in the country to install the technology.