Only around a quarter of the new electricity capacity introduced in 2010 came from wind power, down from 42 percent in 2009, according to a report from the U.S. Department of Energy.

The average cost of installing new wind power held steady in 2010, while the cost of other forms of electricity fell, according to the report.

The cost of installing wind turbines and transmission lines also hasn’t yet caught up with the declining prices of wind turbines. Most wind turbines produced today use a three-blade design, but a number of companies are experimenting with two-blade designs and other designs that are cheaper to manufacture and generate an equivalent amount of electricity.

“Over time everybody coalesced around the same design, but we’re starting to see a lot of diversity again,” said Peter Asmus, a senior analyst with clean technology research firm Pike Research. “We’re seeing lots of vertical axis machines, which a lot of people are skeptical of, and we’re also starting to see some two-bladed machines coming back in.”

The key problems remain building and maintaining new transmission lines, according to the report. It’s easy enough to generate electricity from a wind turbine, but more difficult to move it from point A to point B. It’s a problem that all new types of renewable energy face, Asmus said.

Wind power providers also face concerns about “not-in-my-backyard” complaints from residents in rural areas. There are concerns from a lot of rural residents that the sounds from the wind turbines are disruptive, and that the turbines make for flickering lights because they block out the sun. That has a lot to do with the location of the turbine, because on paper the turbines should not generate that much noise, Asmus said.

“Generally what I’ve heard is that the sound of the wind itself drowns out the sound of the turbine,” Asmus said. “It’s about terrain, the residents get reflections of sound, or they live in something like a valley where the sound ricochets off rocks.”

An independent study by the Maine Department of Environment Protection found the noise from the wind turbines on Vinalhaven registered somewhere between 46 and 47 decibels. The night-time noise pollution limit for areas in Maine is 45 decibels. A typical conversation registers in at around 60 decibels, while typical street traffic registers in at around 70 decibels.

A University of California Berkeley study funded by the U.S. Office of Energy Efficiency and Renewable Energy  showed property values were, at worst, unaffected when wind power farms were installed near each home. While there was a chance that individual homes would be impacted, home sale prices as a whole were not impacted by the placement of wind turbines in the area. Recent complaints show that wind power companies are not doing a good enough job showing the overall impact of wind power turbines on local property taxes.

The United States fell far behind China in terms of wind power added last year as well. China added 18,928 megawatts worth of wind power last year, compared to 5,113 megawatts worth of wind power in the U.S. That means China now generates more electricity from wind power than the United States as of the end of last year. China now generates 44,781 megawatts worth of wind power, compared to 40,267 megawatts worth of wind power generated in the United States.