The answer, or at least a partial answer, to the country's energy woes may be blowin' in the wind.

Wind energy produces no emissions and is the ultimate renewable resource, but for now, it represents just a fraction of the nation's total energy production.

Wind power provides less than 1 percent of electricity in the United States, but last year, it represented the second-largest source of new power generation in the country, trailing new natural gas plants, according to the District-based American Wind Energy Association.

The group says more than 2,400 megawatts of power came from domestic wind-energy parks installed last year. That's enough to power more than 650,000 American homes for a year, on average. President Bush has predicted that wind energy someday will provide as much as 20 percent of the country's electrical needs.

Germany, Denmark and parts of Spain generate 10 percent to 25 percent of their electricity from wind power.

In the United States, wind power has humble roots.

Farmers in the first half of the 20th century used wind power to pump water, but its potential

otherwise remained untapped. The energy crisis of the 1970s bolstered interest, and the recent fighting in the Middle East could mean wind power will enjoy another boost in interest and research.

Steve Fetter, dean of the University of Maryland's School of Public Policy, defines wind power as "extracting the energy out of the moving air through the same aerodynamic forces that give airplanes lift."

A wind-park turbine transforms the kinetic energy from the spinning blades into electrical energy. The machines operate with either a vertical axis or a horizontal axis. The former is the more popular form; the latter looks like a helicopter's propeller system.

A wind park can't be built just anywhere. Mr. Fetter says the location ideally will have steady high-velocity winds.

"The amount of power is proportional to the cube of velocity. Double the wind speed, increase by a factor of eight the power in the wind," he says. "So it's important to find sites with high wind speed for a good fraction of the total number of hours."

Coastal sites, with their unobstructed terrain, generally provide good settings for wind parks. Sites for two parks are being explored on the East Coast. The first would create a 40-turbine, eight-mile park southeast of Long Island's Jones Beach; the other is being proposed off the coast of Cape Cod.

Opponents of these projects, as well as other wind parks, object to their impact on area skylines, their harmful impact upon regional bird populations and relative inefficiency compared to conventional power sources.

Open plains also offer expanses where wind parks can take root, Mr. Fetter says.

"You can still graze cows and grow around them," he says.

John Dunlop, senior outreach representative with the District- based American Wind Energy Association, says misconceptions persist about wind energy. A key misunderstanding, Mr. Dunlop says, is that wind power cannot be integrated into existing utility grids.

"In reality, we can easily integrate it into the grid, and it doesn't need backup power or changes to the utility system," Mr. Dunlop says.

The bigger concern for wind power, and one with a genuine need for more research, is transporting wind energy from the park to faraway sources.

Traditional fuel sources are shipped to where energy is needed, such as an oil truck following the highway to a gas station.

The nearest major wind park to the Washington area is the Mountaineer wind farm next to Blackwater Falls State Park in West Virginia.

Technology is working to boost wind energy's production levels.

"A wind park today is dramatically different than one built 10 years ago," Mr. Dunlop says.

An older model might have a peak output of 300 kilowatts, meaning the energy produced when winds are blowing at around 25 miles per hour or higher. A modern wind park will generate roughly 1,500 kilowatts, he says. Wind-park output is measured by a system's highest energy-production level, even though the wind blowing through any one turbine is typically 30 percent to 40 percent of that high level.

In the case of wind power, it's all about size.

"These new turbines are so much larger, and they're placed on taller towers," Mr. Dunlop says. Some turbines can be up to 40 meters long, he adds. Even the blades are heavier and larger than in previous wind-park models, all to better capture wind and produce more energy.

Other changes will be incremental, he says, designed to prolong the life of the machinery.

Fred Wang, an associate professor in Virginia Tech's Electrical and Computer Engineering Department, says wind energy compares favorably to other alternative energy sources.

"Solar is much less efficient," Mr. Wang says, though solar offers a more consistent resource and one available to most homes across the country.

One consistent criticism of wind parks is the danger they pose to local bird populations.

Mr. Wang says that although any industrial complex comes with the potential for danger, the higher the wind park's blades climb the less likely birds will get ensnared in the blades. In 15 years, he adds, wind power could equal hydropower as a means of energy production stateside.

Mr. Fetter says that unlike solar power, wind power won't be an option for homeowners anytime soon.

"People don't live in these windy areas," he says.

Yet some manufacturers do sell home-friendly systems so people can fulfill some of their energy needs via the wind.

An industry expert who did not want to be named said such systems don't provide an economic boost for the homeowner. They are, for now, aimed at people who want to be as environmentally conscientious as possible, no matter the price tag.

Ultimately, wind energy can play a "not insignificant" role in the country's overall energy supply, Mr. Fetter says.

"Wind might supply as much as 5 or 10 percent of electricity demand," he says. "I don't think it could produce much more than that."

Mr. Dunlop begs to differ.

Though Germany stands as an example of how wind energy can affect a country's energy output, Mr. Dunlop sees great potential stateside.

"Germany leads the entire world in installed wind-energy capacity, but Minnesota alone has five times the wind-energy resources as Germany," he says. "We have the capacity."