Wind energy could theoretically meet global demand yet it provides just about two percent of power consumption. The sector started slowly, but is now one of the most mature of renewable energies.
Worldwide Importance and Future Prospects
Growth in wind power is tremendous, with capacity more than doubling every three years. In 2009, global installed wind capacity reached around 160 Gigawatts, rising 40 GW on the previous year, according to the World Wind Energy Association, which estimates that by 2020 global capacity could reach 1900 GW. Since 2007, annual wind power additions in Europe have exceeded growth of any other power source.
In terms of actual electricity output, global wind power in 2009 generated 340 Terawatt hours per annum, equivalent to the total electricity demand of Italy and equaling two percent of global electricity consumption. Nine percent of Europe’s electricity demand is now being met by wind power, compared to just two percent in 2000.
But Europe no longer leads the market. Recent growth has been driven by Asia, which accounted for 40 percent of new additions in 2009, with China the main locomotive for the international wind industry followed by the United States. Even so, wind energy still accounts for less than one percent of China’s electricity supply.
Further growth will be driven mostly by other rapidly developing countries such as India, Brazil, and Mexico. At the same time, Europe and North America are accelerating offshore wind park development: eight new offshore wind farms were connected to the grid in Europe in 2009.
Global Resources and Producers
Potential land and near-shore wind resources are around 72,000 GW, or five times the world's current energy use, according to a study at by Stanford University.
But sites convenient for wind power production are limited by factors such as land use for agriculture or settlement, distance to consumers, and transmission technology. Experts from the Intergovernmental Panel on Climate Change estimate that only four to ten percent of given wind resources could be used in an economically viable way.
In terms of capacity, the biggest producers of wind energy are the United States, China, Germany, Spain, and India, together accounting for over 70 percent of global capacity.
Denmark produces the most wind energy per capita, and meets roughly 20 percent of its energy needs from wind energy. Other countries with rapidly growing wind power sectors include Canada, France, Britain, Brazil, and Portugal.
Wind power is a 70 billion dollar industry that employs over half a million people worldwide. The turbine market has traditionally been dominated by European companies but Chinese and Indian turbine makers are catching up.
Energy Output
The amount of wind energy generated depends mostly on the size, height, type, and location of a wind turbine. Some small turbines, such as those fixed on a sailboat, generate just a few hundred watts—enough to power a few light bulbs.
At the other end of the spectrum are the large, utility-scale turbines like the Vestas V90 that has a capacity of 3 MW. According to the manufacturer, these turbines produce in 2 to 3 hours the electricity that an average European family consumes in one year.
Most wind power turbines are still installed on land, but the future could lie offshore. Wind speeds over oceans are on average twice as high as over land and more reliable, making offshore wind parks an interesting but technically more challenging and more expensive alternative.
Improving efficiency and falling costs of turbine production and installation will make wind power more price competitive. The cost of producing utility-scale wind power has fallen by 90 percent in the last 20 years. According to General Electric, global prices now range between 3.5 and 4 cents per kilowatt hour, making wind power competitive with energy from coal, oil, nuclear, and natural gas.
Environmental Impact and Drawbacks
Wind turbines—large or small—are not always welcome additions to the landscape. Many people find them loud and unsightly. They are also known to disrupt electro-magnetic communication signals. Others claim that turbines endanger wildlife, particularly birds, although this is disputed.
Germany is already said to be approaching saturation point for onshore wind power production, but investors are looking at big growth potential for offshore wind farms off the coasts of northern Europe and the British Isles.
The biggest technical problem is that wind energy cannot be produced just anywhere; average wind speeds must be good enough to make installing a turbine cost-effective and even the most advanced turbines can extract only a maximum of 45 percent of the wind’s energy.
Energy storage is another issue. Like photovoltaic solar panels, the amount of electricity that wind turbines produce can vary significantly with the weather. This makes it more difficult to incorporate wind power in national grid systems, which have to back-up the turbines with other power sources for those times when the wind doesn’t blow.
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