OLIVER SPRINGS, Tenn. - After an ear-popping, stomach-lurching ride up the side of Buffalo Mountain, Gary Harris steps out into a dense fog that roils with driving rain and nearly gale-force winds.
"This is a great day," he says, straight-faced. "People would say it's bad, but I love it."
For the manager of a program that generates power from the wind, what's not to love? Gusts reaching 30 mph are funneling through the New River valley, swirling across a ridge aptly named Windrock and buffeting the 3,200-foot crest of Buffalo Mountain with a vengeance.
Here, atop towers rising 30 stories, three 75-foot turbine blades create a steady whoosh-whoosh-whoosh noise that's barely audible over the wind. It's music to Harris's ears.
"This is our peak time," said Harris, manager of the Tennessee Valley Authority's Green Power Switch program. "We're getting a lot of kilowatt-hours."
All across its seven-state region, TVA is beginning to generate power in dramatically new and cleaner ways, using wind energy, solar power and methane gas from landfills and sewage lagoons.
Under the Green Power Switch program, 4,700 residential and 200 business customers have agreed to pay somewhat higher prices for the privilege of buying fixed amounts of power from renewable sources.
So great has been the demand that TVA is moving to expand its production of green power. The agency recently solicited proposals that include a plan to build a 20-megawatt wind "farm" on Stone Mountain, near Mountain City, Tenn.
"We've been pleasantly surprised," Harris said.
The high demand for the clean power is especially surprising given that TVA's largest customer, Memphis Light, Gas & Water Division, isn't even offering the option to Shelby County residents yet.
The Memphis utility probably will join the program around next September, after finishing development of a new customer information system that allows for more billing options, said spokesman Mark Heuberger.
Since renewable energy generally costs more to generate than conventional sources like coal-fired plants and hydropower, subscribers to green power pay an extra $4 for each "block" of 150 kilowatt-hours they agree to buy. A 150-kilowatt block represents about 12 percent of an average household's monthly use.
Once it's put on the transmission lines, the electricity from renewable sources can't be distinguished from power emanating from conventional generators. But by paying the higher price, subscribers are covering the costs of putting renewable power on the TVA grid.
Throughout the TVA region, Green Power subscribers have been purchasing an average 1.7 blocks, meaning they're spending $7 more per month than they would if they hadn't joined the program.
Since they were completed in October 2000, the turbines on Buffalo Mountain in East Tennessee have been generating 6 million kilowatt-hours per year - enough power to serve 400 homes.
Between periods of insufficient wind and occasional breakdowns, the turbines are generating power only about 30 percent of the time, Harris said. But the electricity they produce is cheap, costing TVA 7 to 11 cents per kilowatt-hour. That's not much higher than the 6-cent average of conventional sources.
"Wind is actually starting to get somewhat competitive," Harris said.
That's not news to David Blittersdorf, president of the American Wind Energy Association. He said U.S. wind-energy production almost doubled last year. Worldwide, wind is the fastest-growing source of energy.
"The industry really is getting some legs under it and taking off," Blittersdorf said.
In developing wind energy, he said, TVA "is coming along fine," although it hasn't made quite as much progress as another large federal power agency, the Bonneville Power Authority in the Pacific Northwest.
TVA officials say the turbines' performance also quelled doubts and concerns associated with them - including fears that they would be too noisy, interfere with television reception or kill large numbers of birds.
Environmentalists have been pleased as well, said Stephen Smith, executive director of the Southern Alliance for Clean Energy, a group often critical of TVA.
Smith said TVA's commitment to develop wind power has sparked other efforts by producers and utilities.
"Nobody really knew how wind would perform in this part of the country," he said.
Smith sees significant growth potential for wind power in the Tennessee Valley. Still, there are limits to the use of renewable energy, TVA officials say.
"The problem is, no wind, no sun - no power," said Gil Francis, a TVA spokesman. "It (renewable power) cannot replace, it can only supplement our power."