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Wind power
From Wikipedia, the free encyclopedia
For the academic journal, see Wind Energy (journal).
Wind power stations in Xinjiang, China
Global growth of installed capacity[1]
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Wind power is extracted from air flow using wind turbines or sails to produce mechanical or
electrical power. Windmills are used for their mechanical power, windpumps for water pumping,
and sails to propel ships. Wind power as an alternative to fossil fuels, is plentiful, renewable,
widely distributed, clean, produces no greenhouse gas emissions during operation, and uses little
land.[2] The net effects on the environment are far less problematic than those of nonrenewable
power sources.
Wind farms consist of many individual wind turbines which are connected to the electric power
transmission network. Onshore wind is an inexpensive source of electricity, competitive with or
in many places cheaper than coal or gas plants.[3][4][5] Offshore wind is steadier and stronger than
on land, and offshore farms have less visual impact, but construction and maintenance costs are
considerably higher. Small onshore wind farms can feed some energy into the grid or provide
electricity to isolated off-grid locations.[6]
Wind power is very consistent from year to year but has significant variation over shorter time
scales. It is therefore used in conjunction with other electric power sources to give a reliable
supply. As the proportion of windpower in a region increases, a need to upgrade the grid, and a
lowered ability to supplant conventional production can occur.[7][8] Power management
techniques such as having excess capacity, geographically distributed turbines, dispatchable
backing sources, sufficient hydroelectric power, exporting and importing power to neighboring
areas, using vehicle-to-grid strategies or reducing demand when wind production is low, can in
many cases overcome these problems.[9][10] In addition, weather forecasting permits the
electricity network to be readied for the predictable variations in production that occur.[11][12][13]
As of 2014, Denmark has been generating around 40% of its electricity from wind,[14][15] and at
least 83 other countries around the world are using wind power to supply their electricity
grids.[16] Wind power capacity has expanded to 369,553 MW by December 2014,[17] and total
wind energy production is growing rapidly and has reached around 4% of worldwide electricity
usage.[18]
Contents
1 History
2 Wind farms
o 2.1 Generator characteristics and stability
o 2.2 Offshore wind power
o 2.3 Collection and transmission network
3 Wind power capacity and production
o 3.1 Growth trends
o 3.2 Capacity factor
o 3.3 Penetration
o 3.4 Variability
o 3.5 Predictability
o 3.6 Energy storage
o 3.7 Capacity credit, fuel savings and energy payback
4 Economics
o 4.1 Electricity cost and trends
o 4.2 Incentives and community benefits
5 Small-scale wind power
6 Environmental effects
7 Politics
o 7.1 Central government
o 7.2 Public opinion
o 7.3 Community
8 Turbine design
9 Wind energy
10 Gallery
11 See also
12 Notes
13 References
14 Further reading
15 External links
History
Main article: History of wind power
Charles Brush's windmill of 1888, used for generating electricity.
Wind power has been used as long as humans have put sails into the wind. For more than two
millennia wind-powered machines have ground grain and pumped water. Wind power was
widely available and not confined to the banks of fast-flowing streams, or later, requiring sources
of fuel. Wind-powered pumps drained the polders of the Netherlands, and in arid regions such as
the American mid-west or the Australian outback, wind pumps provided water for live stock and
steam engines.
The first windmill used for the production of electricity was built in Scotland in July 1887 by
Prof James Blyth of Anderson's College, Glasgow (the precursor of Strathclyde University).[19]
Blyth's 10 m high, cloth-sailed wind turbine was installed in the garden of his holiday cottage at
Marykirk in Kincardineshire and was used to charge accumulators developed by the Frenchman
Camille Alphonse Faure, to power the lighting in the cottage,[19] thus making it the first house in
the world to have its electricity supplied by wind power.[20] Blyth offered the surplus electricity
to the people of Marykirk for lighting the main street, however, they turned down the offer as
they thought electricity was "the work of the devil."[19] Although he later built a wind turbine to
supply emergency power to the local Lunatic Asylum, Infirmary and Dispensary of Montrose the
invention never really caught on as the technology was not considered to be economically
viable.[19]
Across the Atlantic, in Cleveland, Ohio a larger and heavily engineered machine was designed
and constructed in the winter of 1887-1888 by Charles F. Brush,[21] this was built by his
engineering company at his home and operated from 1886 until 1900.[22] The Brush wind turbine
had a rotor 17 m (56 foot) in diameter and was mounted on an 18 m (60 foot) tower. Although
large by today's standards, the machine was only rated at 12 kW. The connected dynamo was
used either to charge a bank of batteries or to operate up to 100 incandescent light bulbs, three
arc lamps, and various motors in Brush's laboratory.[23]
With the development of electric power, wind power found new applications in lighting
buildings remote from centrally-generated power. Throughout the 20th century parallel paths
developed small wind stations suitable for farms or residences, and larger utility-scale wind
generators that could be connected to electricity grids for remote use of power. Today wind
powered generators operate in every size range between tiny stations for battery charging at
isolated residences, up to near-gigawatt sized offshore wind farms that provide electricity to
national electrical networks.