Wind power offers the potential of clean, inexhaustible, if intermittent, energy.

But where to site wind turbines in relation to homes and communities is a major and growing point of controversy around the world and in the U.S.

Here's why.

Noise

Existing wind-energy facilities in New Mexico lie several miles from the closest communities. But wind turbines proposed for Taos Valley and San Miguel County could be sited much closer to existing homes and villages, from one to one-fourth a mile. The proximity is a major reason residents are concerned about the projects. They believe New Mexico counties and the state need to set stricter noise and distance requirements than currently allowed.

Wind-industry officials and reports say modern wind turbines are "as quiet as a quiet room." They, and some acoustic scientists, believe the only noise that can harm humans - by causing hearing loss - is audible noise.

But a body of published scientific literature, studies and anecdotal evidence from families living closest to wind farms indicate that what people can't hear could hurt them. Some evidence points to the potential for real medical problems from living too close to big wind-energy farms.

In particular, since most wind farms are placed in rural areas where nighttime noise levels are low, the constant swoosh from wind turbine blades is more noticeable than in cities.

Turbines produce low frequency noise below 500 hertz, too low for the human ear to detect, but not too low for human cells to feel, according to some molecular biologists and acoustical scientists. Long-term exposure to the consistent low-frequency noise can lead to what some researchers have dubbed vibroacoustic disease or VAD, with symptoms ranging from heart palpitations and insomnia to migraines and autoimmune disease. Most affected are children, the elderly and people with compromised immune systems. The damage to cells is detectable on brain scans, echocardiography and histological studies, according to some researchers.

VAD is a controversial diagnosis and other scientists, along with the wind industry, debunk it. VAD researchers say a lot more research is needed to understand it, but they warn there's enough evidence to call for better noise testing before deciding on wind turbine sites. They also call for a greater noise limitation on wind energy projects in the U.S., where regulations currently allow higher noise levels than in Europe.

Some counties and states allow wind turbines within 1,000 feet of residences. VAD researchers recommend at least a one mile distance between wind turbines and residences, depending on nighttime noise levels.

Wildlife

Wind-energy facilities share one thing in common with oil and gas developments: They fragment wildlife habitat with roads and pads, according to the New Mexico Department of Game and Fish. The energy may be cleaner, but the construction process and the web of roads between turbines can still disrupt wildlife migrations, impair habitat and cause erosion, according to state wildlife biologists.

But in New Mexico, wind-energy companies don't have to consult with the Department of Game and Fish or do what the agency recommends, unless required to do so by the State Land Office or counties.

Wind turbines also kill birds and bats, though not as many as in the past. The wind industry estimates the count at about two birds per turbine per year. The wind industry says cats, windows and mercury from coal-fired power plants kill more birds than wind turbines.

That's true, but the type of birds killed by wind turbines and the cumulative impact of hundreds more turbines add to the problem, according to Rachel Jankowitz, New Mexico Department of Game and Fish habitat specialist. Since most wind-energy farms in the West are in rural areas and on higher unobstructed ground, they also end up in migratory flyways. Raptors and other migratory birds using those paths tend to reproduce fewer young and are less resilient as a population, Jankowitz said. "I'm sure nobody is really looking at the landscape level, flyways and population impacts if wind energy is developed to say ten times its current level," she said.

Night skies

When tourists drive through Santa Rosa at night, they often want to know what the row of "pretty" flashing red lights are that seem to float in the dark sky south of the town, said Andy Madrid, Guadalupe County's manager. He tells them the lights mark the tops of the 90 wind turbines at the Argonne Mesa Wind Facility.

A similar row of flashing lights worries the people in the communities ringing a mesa in San Miguel County, where a 47-turbine facility is approved.

Keely Meagan, who lives on the mesa, said the night skies over the valley are "gorgeous." Periodic satellites and a single strobe light on top of a 200-foot-tall cell tower on the mesa's northeastern edge already distract a little, she said. "But 47 blinking lights is a lot different from one," she noted.