Wind power is one of the most successful renewable energy resources, but does require backup systems to keep generating energy when the wind is not blowing. Additionally, industrial wind developments can have considerable local aesthetic impacts.
Wind power has been utilized by societies for millennia for a variety of functions, including sea transport and milling. Wind turbines today can be small, powering single homes or businesses, or large enough to power a thousand homes. The average industrial wind turbine today stretches roughly 20 stories into the air with a blade diameter of 200 feet and produces enough power for a couple of hundred homes (approximately one or two megawatts of energy).
More than 80 countries around the world have some sort of modern wind power, totaling almost 200 gigawatts of installed capacity. This installed capacity equates to just over 2 percent of annual global electricity consumption. The United States was recently surpassed by China as the world’s largest wind power producer, with a total of 44 gigawatts. Denmark, followed by Portugal and then Spain, have the highest proportion of electricity generation from wind, at 21, 18, and 16 percent, respectively. By comparison, the 40 gigawatts produced from wind in the United States represent only 2 percent of total electricity consumption.
The energy return on energy invested for wind power is upwards of 20:1–30:1, which is comparable to that of fossil fuels, and higher than most other renewable resources. However, this figure does not reflect that wind is an intermittent source of energy. Achieving the full benefits of wind power at a large scale requires solving the problem of intermittency with better energy storage technology and smooth integration of baseload generating sources and renewables. Numerous efforts in these areas are underway, including development of smarter electrical grids that may accommodate a high percentage of renewably generated power, but these infrastructure improvements will be expensive.
Although concerns about the negative effects of wind turbines on birds have largely been resolved, other nonenergy-related complications remain, namely local complaints about noise and shadow flicker from blades, and concerns about the visual impact of large facilities. Additionally, wind power tends to be best on mountaintops or offshore—areas that can be tough to reach and may lack electrical infrastructure. New transmission capacity can fragment wildlife habitat. Lastly, due to the fact that wind power is not energy dense, the footprint for a system of wind turbines compared to that of a coal mine or oil and gas field is much larger per energy unit, which may cause increased land-cover degradation and habitat destruction.