The propeller-like blades of wind turbines are finding their way to the rooftops of corporate headquarters, high-rise residential towers, government structures and even a ski resort.

The rising cost of energy, the sharply falling cost of air-driven turbines — 90% less expensive than in 1985 — and a new corporate commitment to “go green” are all feeding the wind machine.

Lily Development LLC, developer of Aquarius Tower, a 38-story condominium high-rise in downtown Atlanta, has designed rooftop turbines resembling a stack of circles. The turbines are expected to supply up to 20% of the 270,000 sq. ft. building's energy needs.

“We've come up with an innovative idea for the building that everyone else can copy,” says developer Antonio Escandari. Aquarius is scheduled to be completed in fall 2009. Although Escandari did not disclose the cost, according to the American Wind Energy Association, a non-profit group based in Washington, D.C., it costs about $1.3 million to produce 1 megawatt of energy with a wind turbine.

While wind power currently supplies less than 1% of national energy needs, construction of turbines is rising sharply with 2,000 new installations anticipated this year, according to the association. Although most new turbines will be installed on wind farms, a growing number are rising at schools, government structures and office buildings.

Staples, the office supply superstore, plans to install turbines atop its headquarters in Framingham, Mass., to help the corporate giant save energy.

Arguably the most flamboyant application of wind power was the August 2007 start of a giant turbine at the Jiminy Mountain Ski Resort in the Western Berkshires region of Massachusetts. Three propeller-like blades measuring 127 feet power the turbine.

The ski resort expects “Zephyr,” its name for the turbine, to pay for itself in seven years. The payback time on investment in wind power can be shorter than for solar power, especially when grants and incentives are available, according to industry experts.

Photovoltaics take nearly 40 years to pay for themselves, although incentives and tax rebates can lower that figure to 7.5 years, reports Solar Power Generation, a Florida-based manufacturer.

“Wind energy is more efficient than photovoltaics,” says Tyler Leeds, an engineer at the Massachusetts Technology Collaborative, who says Zephyr is expected to generate nearly 50% of the ski resort's energy requirement.

The downside of wind energy is that the turbines are often huge, since size matters in generating wind. The turbine at Jiminy Mountain stands 368 feet tall.

Wind speeds increase with height. But not all locations work equally well for wind power, and even small variations in wind speed can translate into big differentials in the cost of producing energy.

What's more, tall turbines can pose hazards for small aircraft and even for birds. Protesting one proposed wind farm in 1999 near the habitat of the rare California condor, local environmentalists decried the turbine blades as “condor Cuisinarts.”

Haitham Haddad, a principal of PFVS, the architecture firm designing the Aquarius Tower in downtown Atlanta, says egg-beater-shaped blades may be less likely to injure winged creatures. “The birds will feel the wind,” says the architect, “and they will stay away.”