[[PASTING TABLES IS NOT SUPPORTED]]
Wind power is the conversion of
wind energy into a useful form of energy, such as using:
wind turbines to make electricity,
windmills for mechanical power,
windpumps for
water pumping or
drainage, or
sails to propel ships.
A large
wind farm may consist of several hundred individual
wind turbines which are connected to the
electric power transmission
network. Offshore wind farms can harness more frequent and powerful
winds than are available to land-based installations and have less
visual impact on the landscape but construction costs are considerably
higher. Small onshore wind facilities are used to provide electricity to
isolated locations and utility companies increasingly
buy back surplus electricity produced by small domestic wind turbines.
Although a variable source of power, the
intermittency
of wind seldom creates problems when used to supply up to 20% of total
electricity demand, but as the proportion increases problems arise such
as: increased costs, a need to use storage such as
pumped-storage hydroelectricity, a need to upgrade the grid, or a lowered ability to supplant conventional production.
[1][2][3]
Power management techniques such as: excess capacity storage,
dispatchable backing supply (usually natural gas), exporting and
importing power to neighboring areas or reducing demand when wind
production is low, can mitigate these problems.
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.
[4] The overall cost per unit of energy produced is similar to the cost for new coal and natural gas installations.
[5] Any
effects on the environment
are generally less problematic than those from other power sources.
Although wind power is a popular form of energy generation, the
construction of wind farms is not universally welcomed.
[6][7][8][9][10][11][12]
[[PASTING TABLES IS NOT SUPPORTED]] History
Blyth's "windmill" at his cottage in Marykirk in 1891
The first practical windmills were in use in Iran at least by the 9th century and possibly as early as the 7th century.
[13] The use of windmills became widespread use across the Middle East and Central Asia, and later spread to China and India.
[14] By 1000 AD, windmills were used to pump seawater for
salt-making in China and Sicily.
[15] Windmills were used extensively in Northwestern Europe to grind flour from the 1180s,
[14] and
windpumps were used to drain land for agriculture and for building.
[16] Early immigrants to the
New World brought the technology with them from Europe.
[16]
In
the US, the development of the "water-pumping windmill" was the major
factor in allowing the farming and ranching of vast areas otherwise
devoid of readily accessible water. Windpumps contributed to the
expansion of rail transport systems throughout the world, by pumping
water from water wells for
steam locomotives.
[17]
The multi-bladed wind turbine atop a lattice tower made of wood or
steel was, for many years, a fixture of the landscape throughout rural
America.
Electricity generation In July 1887, a Scottish academic, Professor
James Blyth,
built a cloth-sailed wind turbine in the garden of his holiday cottage
in Marykirk and used the electricity it produced to charge
accumulators which he used to power the lights in his cottage.
[18] His experiments culminated in a UK patent in 1891.
[19] In the winter of 1887/8 US inventor
Charles F. Brush
produced electricity using a wind powered generator which powered his
home and laboratory until about 1900. In the 1890s, the Danish scientist
and inventor
Poul la Cour constructed wind turbines to generate electricity, which was used to produce
hydrogen and
Oxygen by
electrolysis and a mixture of the two gases was stored for use as a fuel.
[19]
La Cour was the first to discover that fast rotating wind turbines with
fewer rotor blades were the most efficient in generating electricity
and in 1904 he founded the Society of Wind Electricians.
[20]
By the mid-1920s, 1 to 3-kilowatt wind generators developed by companies such as
Parris-Dunn
and Jacobs Wind-electric found widespread use in the rural areas of the
midwestern Great Plains of the US but by the 1940s the demand for more
power and the coming of the electrical grid throughout those areas made
these small generators obsolete.
[21]
During
the 1920s the first vertical axis wind turbine was built by Frenchman
George Darrieus and in 1931 a 100 kW precursor to the modern horizontal
wind generator was used in Yalta, in the USSR. In 1956 Johannes Juul, a
former student of la Cour, built a 200 kW, three-bladed turbine at
Gedser in Denmark, which influenced the design af many later turbines.
[20]
In 1975 the
United States Department of Energy funded a project to develop utility-scale wind turbines. The
NASA wind turbines project built thirteen experimental turbines which paved the way for much of the technology used today.
[20]
Since then, turbines have increased greatly in size with the Enercon
E-126 capable of delivering up to 7 MW. Wind turbine production has
expanded to many countries and wind power is expected to grow worldwide
in the twenty-first century.
[22]
Wind energy
Map of available wind power for the
United States. Color codes indicate wind power density class.
Wind is the movement of air across the surface of the Earth, from areas of high pressure to areas of low pressure.
[23]
The surface of the Earth is heated unevenly by the Sun, depending on
factors such as the angle of incidence of the sun's rays at the surface
(which differs with latitude and time of day) and whether the land is
open or covered with vegetation. Also, large bodies of water, such as
the oceans, heat up and cool down slower than the land. The heat energy
absorbed at the Earth's surface is transferred to the air directly above
it and, as warmer air is less dense than cooler air, it rises above the
cool air to form areas of high pressure and thus pressure
differentials. The rotation of the Earth drags the atmosphere around
with it causing turbulence. These effects combine to cause a constantly
varying pattern of winds across the surface of the Earth.
[23]
The
total amount of economically extractable power available from the wind
is considerably more than present human power use from all sources.
[24]
Axel Kleidon of the Max Planck Institute in Germany, carried out a "top
down" calculation on how much wind energy there is, starting with the
incoming solar radiation that drives the winds by creating temperature
differences in the atmosphere. He concluded that somewhere between 18 TW
and 68 TW could be extracted.
[25] Cristina Archer and
Mark Z. Jacobson
presented a "bottom-up" estimate, which unlike Kleidon's are based on
actual measurements of wind speeds, and found that there is 1700 TW of
wind power at an altitude of 100 metres over land and sea. Of this,
"between 72 and 170 TW could be extracted in a practical and
cost-competitive manner".
[25]
Distribution of wind speed
Distribution of wind speed (red) and energy (blue) for all of 2002 at
the Lee Ranch facility in Colorado. The histogram shows measured data,
while the curve is the Rayleigh model distribution for the same average
wind speed.
The strength of wind varies, and an
average value for a given location does not alone indicate the amount of
energy a wind turbine could produce there. To assess the frequency of
wind speeds at a particular location, a probability distribution
function is often fit to the observed data. Different locations will
have different wind speed distributions. The
Weibull
model closely mirrors the actual distribution of hourly wind speeds at
many locations. The Weibull factor is often close to 2 and therefore a
Rayleigh distribution can be used as a less accurate, but simpler model.
Wind farms
A wind farm is a group of
wind turbines
in the same location used for production of electricity. A large wind
farm may consist of several hundred individual wind turbines, and cover
an extended area of hundreds of square miles, but the land between the
turbines may be used for agricultural or other purposes. A wind farm may
also be located offshore.
Almost all large wind turbines have
the same design — a horizontal axis wind turbine having an upwind rotor
with three blades, attached to a nacelle on top of a tall tubular tower.
In a
wind farm,
individual turbines are interconnected with a medium voltage (often
34.5 kV), power collection system and communications network. At a
substation, this medium-voltage electric current is increased in voltage
with a
transformer for connection to the high voltage
electric power transmission system.
Many of the largest operational onshore wind farms are located in the US. As of November 2010, the
Roscoe Wind Farm is the largest onshore wind farm in the world at 781.5 MW, followed by the
Horse Hollow Wind Energy Center (735.5 MW). As of November 2010, the
Thanet Wind Farm in the UK is the largest offshore wind farm in the world at 300 MW, followed by
Horns Rev II (209 MW) in Denmark.
There are many large wind farms under construction including;
The London Array (offshore) (1000 MW),
BARD Offshore 1 (400 MW),
Sheringham Shoal Offshore Wind Farm (317 MW),
Lincs Wind Farm (offshore, (270 MW)
Shepherds Flat Wind Farm (845 MW),
Clyde Wind Farm (548 MW),
Greater Gabbard wind farm (500 MW),
Macarthur Wind Farm (420 MW),
Shepherds Flat Wind Farm (845 MW),
Lower Snake River Wind Project (343 MW) and
Walney Wind Farm (367 MW).
Feeding into grid
Induction generators, often used for wind power, require
reactive power for
excitation so
substations used in wind-power collection systems include substantial
capacitor banks for
power factor correction. Different types of wind turbine generators behave differently during transmission grid disturbances, so
extensive modelling
of the dynamic electromechanical characteristics of a new wind farm is
required by transmission system operators to ensure predictable stable
behaviour during system faults (see:
Low voltage ride through).
In particular, induction generators cannot support the system voltage
during faults, unlike steam or hydro turbine-driven synchronous
generators.
Doubly fed machines generally have more desirable properties for grid interconnection.[
citation needed] Transmission systems operators will supply a wind farm developer with a
grid code to specify the requirements for interconnection to the transmission grid. This will include
power factor, constancy of
frequency and dynamic behavior of the wind farm turbines during a system fault.
[26][27]
Offshore wind power
Offshore
wind power refers to the construction of wind farms in large bodies of
water to generate electricity. These installations can utilise the more
frequent and powerful winds that are available in these locations and
have less aesthetic impact on the landscape than land based projects but
construction and maintenance costs are considerably higher.
[28][29] Currently, offshore wind farms are at least 3 times more expensive than onshore wind farms of the same nominal power
[30] but these costs are expected to fall as the industry matures.
[31]
Siemens and
Vestas are the leading turbine suppliers for offshore wind power.
DONG Energy,
Vattenfall and
E.ON are the leading offshore operators.
[32] As of October 2010, 3.16 GW of offshore wind power capacity was operational, mainly in Northern Europe. According to
BTM Consult,
more than 16 GW of additional capacity will be installed before the end
of 2014 and the UK and Germany will become the two leading markets.
Offshore wind power capacity is expected to reach a total of 75 GW
worldwide by 2020, with significant contributions from China and the US.
[32]
Wind power capacity and production
Worldwide installed wind power capacity (Source:
GWEC)
[33]
Worldwide there are now many thousands of wind turbines operating, with a total
nameplate capacity of 238,351 MW as of end 2011.
[34] World wind generation capacity more than quadrupled between 2000 and 2006, doubling about every three years.
The United States pioneered wind farms
and led the world in installed capacity in the 1980s and into the
1990s. In 1997 German installed capacity surpassed the U.S. and led
until once again overtaken by the U.S. in 2008. China
has been rapidly expanding its wind installations in the late 2000s and passed the U.S. in 2010 to become the world leader.
At the end of 2011, worldwide
nameplate capacity of wind-powered generators was 238
gigawatts (GW), growing by 41 GW over the preceding year.
[35] 2010 data from the
World Wind Energy Association,
an industry organization states that wind power now has the capacity to
generate 430 TWh annually, which is about 2.5% of worldwide electricity
usage.
[36][37] Between 2005 and 2010 the average annual growth in new installations was 27.6 percent.
[38] Wind power market penetration is expected to reach 3.35 percent by 2013 and 8 percent by 2018.
[38][39]
Several countries have already achieved relatively high levels of
penetration, such as 28% of stationary (grid) electricity production in
Denmark (2011),
[40] 19% in
Portugal (2011),
[41] 16% in
Spain (2011),
[42] 14% in
Ireland (2010)
[43] and 8% in
Germany (2011).
[44] As of 2011, 83 countries around the world were using wind power on a commercial basis.
[45]
Europe
accounted for 48% of the world total wind power generation capacity in
2009. In 2010, Spain became Europe's leading producer of wind energy,
achieving 42,976 GWh. Germany held the top spot in Europe in terms of
installed capacity, with a total of 27,215 MW as of 31 December 2010.
[46]
[[PASTING TABLES IS NOT SUPPORTED]] Growth trends
Worldwide installed capacity 1997–2020 [MW], developments and prognosis. Data source: WWEA
[49]
Worldwide installed wind power capacity forecast (Source: Global Wind Energy Council)
[33][50]
In
2010, more than half of all new wind power was added outside of the
traditional markets in Europe and North America. This was largely from
new construction in China, which accounted for nearly half the new wind
installations (16.5 GW).
[51]
Global
Wind Energy Council (GWEC) figures show that 2007 recorded an increase
of installed capacity of 20 GW, taking the total installed wind energy
capacity to 94 GW, up from 74 GW in 2006. Despite constraints facing
supply chains for wind turbines, the annual market for wind continued to
increase at an estimated rate of 37%, following 32% growth in 2006. In
terms of economic value, the wind energy sector has become one of the
important players in the energy markets, with the total value of new
generating equipment installed in 2007 reaching €25 billion, or US$36
billion.
[52]
Although the
wind power industry was affected by the
global financial crisis in 2009 and 2010, a
BTM Consult
five year forecast up to 2013 projects substantial growth. Over the
past five years the average growth in new installations has been 27.6
percent each year. In the forecast to 2013 the expected average annual
growth rate is 15.7 percent.
[38][39]
More than 200 GW of new wind power capacity could come on line before
the end of 2013. Wind power market penetration is expected to reach 3.35
percent by 2013 and 8 percent by 2018.
[38][39]
Typical components of a wind turbine (
gearbox, rotor shaft and brake assembly) being lifted into position
Capacity factor Since
wind speed is not constant, a wind farm's annual energy production is
never as much as the sum of the generator nameplate ratings multiplied
by the total hours in a year. The ratio of actual productivity in a year
to this theoretical maximum is called the
capacity factor. Typical capacity factors are 20–40%, with values at the upper end of the range in particularly favourable sites.
[53][nb 1] Online data is available for some locations and the capacity factor can be calculated from the yearly output.
[54][55]
Unlike
fueled generating plants the capacity factor is affected by several
parameters, including the variability of the wind at the site but also
the generator size. A small generator would be cheaper and achieve a
higher capacity factor but would produce less electricity (and thus less
profit) in high winds.
[56]
Conversely, a large generator would cost more but generate little extra
power and, depending on the type, may stall out at low wind speed. Thus
an optimum capacity factor would be aimed for, which is usually around
20–35%.
In a 2008 study released by the U.S. Department of
Energy's Office of Energy Efficiency and Renewable Energy, the capacity
factor achieved by the U.S. wind turbine fleet is shown to be increasing
as the technology improves. The capacity factor achieved by new wind
turbines in 2004 and 2005 reached 36%.
[57]
Penetration Wind
energy penetration refers to the fraction of energy produced by wind
compared with the total available generation capacity. There is no
generally accepted maximum level of wind penetration. The limit for a
particular grid will depend on the existing generating plants, pricing
mechanisms, capacity for storage or demand management and other factors.
An interconnected electricity grid will already include reserve
generating and transmission capacity to allow for equipment failures.
This reserve capacity can also serve to compensate for the varying power
generation produced by wind plants. Studies have indicated that 20% of
the total annual electrical energy consumption may be incorporated with
minimal difficulty.
[58]
These studies have been for locations with geographically dispersed
wind farms, some degree of dispatchable energy or hydropower with
storage capacity, demand management, and interconnected to a large grid
area enabling the export of electricity when needed. Beyond the 20
percent level, there are few technical limits, but the economic
implications become more significant. Electrical utilities continue to
study the effects of large (20% or more) scale penetration of wind
generation on system stability and economics.
[59][60][61][62]
A
wind energy penetration figure can be specified for different durations
of time. On an annual basis, as of 2011, few grid systems have
penetration levels above five percent: Denmark - 26%, Portugal - 17%,
Spain - 15%, Ireland - 14%, and Germany - 9%.
[63] For the U.S. in 2011, the penetration level was estimated at 2.9%.
[63]
Variability and intermittency
Electricity
generated from wind power can be highly variable at several different
timescales: hourly, daily, or seasonally. Annual variation also exists,
but is not as significant. Like other electricity sources, wind energy
must be scheduled. Wind power forecasting methods are used, but
predictability of wind plant output remains low for short-term
operation.[
citation needed]
Because instantaneous electrical generation and consumption must remain
in balance to maintain grid stability, this variability can present
substantial challenges to incorporating large amounts of wind power into
a grid system. Intermittency and the non-
dispatchable nature of wind energy production can raise costs for regulation, incremental
operating reserve, and (at high penetration levels) could require an increase in the already existing
energy demand management,
load shedding, storage solutions or system interconnection with
HVDC
cables. At low levels of wind penetration, fluctuations in load and
allowance for failure of large generating units require reserve capacity
that can also compensae for variability of wind generation. Wind power
can be replaced by other power sources during low wind periods.
Transmission networks must already cope with outages of generation plant
and daily changes in electrical demand. Systems with large wind
capacity components may need more spinning reserve (plants operating at
less than full load).
[64][65]
Pumped-storage hydroelectricity or other forms of
grid energy storage can store energy developed by high-wind periods and release it when needed.
[66]
Stored energy increases the economic value of wind energy since it can
be shifted to displace higher cost generation during peak demand
periods. The potential revenue from this
arbitrage
can offset the cost and losses of storage; the cost of storage may add
25% to the cost of any wind energy stored but it is not envisaged that
this would apply to a large proportion of wind energy generated. For
example, in the UK, the 2 GW
Dinorwig pumped storage plant
evens out electrical demand peaks, and allows base-load suppliers to
run their plant more efficiently. Although pumped storage power systems
are only about 75% efficient, and have high installation costs, their
low running costs and ability to reduce the required electrical
base-load can save both fuel and total electrical generation costs.
[67][68]
While
the output from a single turbine can vary greatly and rapidly as local
wind speeds vary, as more turbines are connected over larger and larger
areas the average power output becomes less variable.
[69]
Studies by Graham Sinden (2009) suggest that, in practice, the
variations in thousands of wind turbines, spread out over several
different sites and wind regimes, are smoothed, rather than
intermittent. As the distance between sites increases, the correlation
between wind speeds measured at those sites, decreases.
[70]
In
particular geographic regions, peak wind speeds may not coincide with
peak demand for electrical power. In the US states of California and
Texas, for example, hot days in summer may have low wind speed and high electrical demand due to the use of
air conditioning. Some utilities subsidize the purchase of
geothermal heat pumps by their customers, to reduce electricity demand during the summer months by making air conditioning up to 70% more efficient;
[71]
widespread adoption of this technology would better match electricity
demand to wind availability in areas with hot summers and low summer
winds. Another option is to interconnect widely dispersed geographic
areas with an HVDC "
Super grid".
In the U.S. it is estimated that to upgrade the transmission system to
take in planned or potential renewables would cost at least $60 billion.
[72]
Solar power tends to be complementary to wind.
[73][74] On daily to weekly timescales,
high pressure areas tend to bring clear skies and low surface winds, whereas
low pressure areas
tend to be windier and cloudier. On seasonal timescales, solar energy
typically peaks in summer, whereas in many areas wind energy is lower in
summer and higher in winter.
[75]
Thus the intermittencies of wind and solar power tend to cancel each
other somewhat. The Institute for Solar Energy Supply Technology of the
University of Kassel pilot-tested a
combined power plant linking solar, wind,
biogas and
hydrostorage to provide load-following power around the clock, entirely from renewable sources.
[76]
[[PASTING TABLES IS NOT SUPPORTED]] A 2006
International Energy Agency
forum presented costs for managing intermittency as a function of
wind-energy's share of total capacity for several countries, as shown in
the table on the right. Three reports on the wind variability in the UK
issued in 2009, generally agree that variability of wind needs to be
taken into account, but it does not make the grid unmanageable. The
additional costs, which are modest, can be quantified.
[77]
A
report on Denmark's wind power noted that their wind power network
provided less than 1% of average demand on 54 days during the year 2002.
[78]
Wind power advocates argue that these periods of low wind can be dealt
with by simply restarting existing power stations that have been held in
readiness, or interlinking with HVDC.
[79]
Electrical grids with slow-responding thermal power plants and without
ties to networks with hydroelectric generation may have to limit the use
of wind power.
[78]
Conversely,
on particularly windy days, even with penetration levels of 16%, wind
power generation can surpass all other electricity sources in a country.
[80]
In Spain, on 8 November 2009 wind power production reached the highest
percentage of electricity production till then, with wind farms covering
53% of the total demand.
[81][82]
Capacity credit and fuel savings The
capacity credit of wind is estimated by determining the capacity of
conventional plants displaced by wind power, whilst maintaining the same
degree of system security,.
[83] However, the precise value is irrelevant since the main value of wind (in the UK, worth 5 times the capacity credit value
[84]) is its fuel and CO2 savings.[
citation needed]
According to a 2007 Stanford University study published in the Journal
of Applied Meteorology and Climatology, interconnecting ten or more wind
farms can allow an average of 33% of the total energy produced to be
used as reliable,
baseload electric power, as long as minimum criteria are met for wind speed and turbine height.
[85][86]
Economics Cost trends
Landowners in the US typically receive $3,000 to $5,000 per year in
rental income from each wind turbine, while farmers continue to grow
crops or graze cattle up to the foot of the turbines.
[70] Shown: the
Brazos Wind Farm in Texas.
Wind power has low ongoing costs, but a moderate capital cost. The estimated
average cost
per unit incorporates the cost of construction of the turbine and
transmission facilities, borrowed funds, return to investors (including
cost of risk), estimated annual production, and other components,
averaged over the projected useful life of the equipment, which may be
in excess of twenty years. Energy cost estimates are highly dependent on
these assumptions so published cost figures can differ substantially. A
2011 report from the American Wind Energy Association stated, "Wind's
costs have dropped over the past two years, in the range of 5 to 6 cents
per kilowatt-hour recently.... about 2 cents cheaper than coal-fired
electricity, and more projects were financed through debt arrangements
than tax equity structures last year.... winning more mainstream
acceptance from Wall Street's banks.... Equipment makers can also
deliver products in the same year that they are ordered instead of
waiting up to three years as was the case in previous cycles.... 5,600
MW of new installed capacity is under construction in the United States,
more than double the number at this point in 2010. Thirty-five percent
of all new power generation built in the United States since 2005 has
come from wind, more than new gas and coal plants combined, as power
providers are increasingly enticed to wind as a convenient hedge against
unpredictable commodity price moves."
[87]
A turbine blade convoy passing through
Edenfield in the U.K. (2008). Even longer
two-piece blades are now manufactured, and then assembled on-site to reduce difficulties in transportion.
A
British Wind Energy Association report gives an average generation cost
of onshore wind power of around 3.2 pence (between US 5 and 6 cents)
per kW·h (2005).
[88]
Cost per unit of energy produced was estimated in 2006 to be comparable
to the cost of new generating capacity in the US for coal and natural
gas: wind cost was estimated at $55.80 per MW·h, coal at $53.10/MW·h and
natural gas at $52.50.
[5] Similar comparative results with natural gas were obtained in a governmental study in the UK in 2011.
[89]
Other sources in various studies have estimated wind to be more
expensive than other sources. A 2009 study on wind power in Spain by
Gabriel Calzada Alvarez
Universidad Rey Juan Carlos
concluded that each installed MW of wind power led to the loss of 4.27
jobs, by raising energy costs and driving away electricity-intensive
businesses.
[90] The U.S. Department of Energy found the study to be seriously flawed, and the conclusion unsupported.
[91]
The presence of wind energy, even when subsidised, can reduce costs for
consumers (€5 billion/yr in Germany) by reducing the marginal price by
minimising the use of expensive 'peaker plants'.
[92]
The
marginal cost of wind energy once a plant is constructed is usually less than 1 cent per kW·h.
[93]
In 2004, wind energy cost a fifth of what it did in the 1980s, and some
expected that downward trend to continue as larger multi-megawatt
turbines were mass-produced.
[94] As of 2012 capital costs for wind turbines are substantially lower than 2008-2010 but are still above 2002 levels.
[95]
Incentives
Some of the more than 6,000 wind turbines in the
Altamont Pass Wind Farm,
in California, United States. Developed during a period of tax
incentives in the 1980s, this wind farm has more turbines than any other
in the US.
[96]
Wind energy in many jurisdictions receives financial or other support to encourage its development. Wind energy benefits from
subsidies
in many jurisdictions, either to increase its attractiveness, or to
compensate for subsidies received by other forms of production which
have significant negative externalities.
In the US, wind power
receives a tax credit for each kW·h produced; at 1.9 cents per kW·h in
2006, the credit has a yearly inflationary adjustment. Another tax
benefit is
accelerated depreciation.
Many American states also provide incentives, such as exemption from
property tax, mandated purchases, and additional markets for "
green credits". Countries such as
Canada
and Germany also provide incentives for wind turbine construction, such
as tax credits or minimum purchase prices for wind generation, with
assured grid access (sometimes referred to as
feed-in tariffs). These feed-in tariffs are typically set well above average electricity prices. The
Energy Improvement and Extension Act of 2008 contains extensions of credits for wind, including microturbines.
Secondary market forces also provide incentives for businesses to use wind-generated power, even if there is a
premium price for the electricity. For example,
socially responsible manufacturers
pay utility companies a premium that goes to subsidize and build new
wind power infrastructure. Companies use wind-generated power, and in
return they can claim that they are undertaking strong "green" efforts.
In the US the organization Green-e monitors business compliance with
these renewable energy credits.
[97]
Environmental effects
Livestock ignore wind turbines,
[98] and continue to graze as they did before wind turbines were installed.
Compared
to the environmental impact of traditional energy sources, the
environmental impact of wind power is relatively minor. Wind power
consumes no fuel, and emits no air pollution, unlike fossil fuel power
sources. The energy consumed to manufacture and transport the materials
used to build a wind power plant is equal to the new energy produced by
the plant within a few months. While a wind farm may cover a large area
of land, many land uses such as agriculture are compatible, with only
small areas such as turbine foundations and infrastructure made
unavailable for use.
[6]
Wind
farms need to be located in windy areas for greater efficiency, which
often leads them to be placed on the top of ridges and hills, where they
are particularly visible. This leads some to complain that they 'ruin
the landscape'.
[99] While aesthetic issues are subjective and others find wind farms pleasant and optimistic, or symbols of
energy independence and local prosperity,
[100] groups of people
[101] often organize to attempt to politically block new wind power sites.
[99]
There
are reports of bird and bat mortality at wind turbines as there are
around other artificial structures. The scale of the ecological impact
may
[102] or may not
[103]
be significant, depending on specific circumstances. Environmental
assessment of proposed wind farm projects can mitigate or prevent
wildlife fatalities and help protect fragile habitats such as
peat bogs[104][105]
Politics Central government Fossil fuels are
subsidized by many governments,
and wind power and other forms of renewable energy are also often
subsidized. For example a 2009 study by the Environmental Law Institute
[106]
assessed the size and structure of U.S. energy subsidies over the
2002–2008 period. The study estimated that subsidies to fossil-fuel
based sources amounted to approximately $72 billion over this period and
subsidies to renewable fuel sources totaled $29 billion. In the United
States, the federal government has paid US$74 billion for energy
subsidies to support
R&D for
nuclear power ($50 billion) and
fossil fuels ($24 billion) from 1973 to 2003. During this same timeframe,
renewable energy technologies and
energy efficiency
received a total of US$26 billion. It has been suggested that a subsidy
shift would help to level the playing field and support growing energy
sectors, namely
solar power, wind power, and
biofuels.
[107] History shows that no energy sector was developed without subsidies.
[107]
According to
IEA
(2011) energy subsidies artificially lower the price of energy paid by
consumers, raise the price received by producers or lower the cost of
production. "Fossil fuels subsidies costs generally outweigh the
benefits. Subsidies to renewables and low-carbon energy technologies can
bring long-term economic and environmental benefits".
[108] In November 2011, an IEA report entitled
Deploying Renewables 2011
said "subsidies in green energy technologies that were not yet
competitive are justified in order to give an incentive to investing
into technologies with clear environmental and energy security
benefits". The IEA's report disagreed with claims that renewable energy
technologies are only viable through costly subsidies and not able to
produce energy reliably to meet demand.
In the US, the wind power
industry has recently increased its lobbying efforts considerably,
spending about $5 million in 2009 after years of relative obscurity in
Washington.
[109]
By comparison, the US nuclear industry alone spent over $650 million on
its lobbying efforts and campaign contributions during a single ten
year period ending in 2008.
[110][111][112]
Following the
2011 Japanese nuclear accidents, Germany's federal government is working on a new plan for increasing
energy efficiency and
renewable energy commercialization, with a particular focus on
offshore wind farms. Under the plan large
wind turbines
will be erected far away from the coastlines, where the wind blows more
consistently than it does on land, and where the enormous turbines
won't bother the inhabitants. The plan aims to decrease Germany's
dependence on energy derived from coal and nuclear power plants.
[113]
Commenting on the
EU's 2020 renewable energy target,
Economist, Professor Dieter Helm, is critical of how the costs of wind
power are cited by lobbyists. Helm also says that the problem of
intermittent supply will probably lead to another
dash-for-gas or dash-for-coal in Europe, possibly with a negative impact on
energy security.
[114] A
House of Lords Select Committee
report (2008) on renewable energy in the UK reported a "concern over
the prospective role of wind generated and other intermittent sources of
electricity in the UK, in the absence of a break-through in electricity
storage technology or the integration of the UK grid with that of
continental Europe".
[115]
Public opinion Surveys of public attitudes across Europe and in many other countries show strong public support for wind power.
[8][9][10] About 80 percent of EU citizens support wind power.
[11]
In Germany, where wind power has gained very high social acceptance,
hundreds of thousands of people have invested in citizens' wind farms
across the country and thousands of small and medium sized enterprises
are running successful businesses in a new sector that in 2008 employed
90,000 people and generated 8 percent of Germany's electricity.
[116][117]
In
Spain, with some exceptions, there has been little opposition to the
installation of inland wind parks. However, the projects to build
offshore parks have been more controversial.
[118]
In particular, the proposal of building the biggest offshore wind power
production facility in the world in southwestern Spain in the coast of
Cádiz, on the spot of the 1805
Battle of Trafalgar.
[119] has been met with strong opposition who fear for tourism and fisheries in the area,
[120] and because the area is a war grave.
[119]
In
a survey conducted by Angus Reid Strategies in October 2007, 89 per
cent of respondents said that using renewable energy sources like wind
or solar power was positive for Canada, because these sources were
better for the environment. Only 4 per cent considered using renewable
sources as negative since they can be unreliable and expensive.
[121]
According to a Saint Consulting survey in April 2007, wind power was
the alternative energy source most likely to gain public support for
future development in Canada, with only 16% opposed to this type of
energy. By contrast, 3 out of 4 Canadians opposed nuclear power
developments.
[122]
A
2003 survey of residents living around Scotland's 10 existing wind
farms found high levels of community acceptance and strong support for
wind power, with much support from those who lived closest to the wind
farms. The results of this survey support those of an earlier Scottish
Executive survey 'Public attitudes to the Environment in Scotland 2002',
which found that the Scottish public would prefer the majority of their
electricity to come from renewables, and which rated wind power as the
cleanest source of renewable energy.
[123]
A survey conducted in 2005 showed that 74% of people in Scotland agree
that wind farms are necessary to meet current and future energy needs.
When people were asked the same question in a Scottish Renewables study
conducted in 2010, 78% agreed. The increase is significant as there were
twice as many wind farms in 2010 as there were in 2005. The 2010 survey
also showed that 52% disagreed with the statement that wind farms are
"ugly and a blot on the landscape". 59% agreed that wind farms were
necessary and that how they looked was unimportant.
[124][125]
Despite this general support for the concept of wind power in the public at large,
local opposition often exists and has delayed or aborted a number of projects. This type of opposition is often described as
NIMBYism,
[126]
but research carried out in 2009 found that there is little evidence to
support the belief that residents only object to renewable power
facilities such as wind turbines as a result of a "Not In My Back Yard"
attitude.
[127]
Community
See also Renewable energy debate –Community debate about wind farms
Wind turbines such as these, in
Cumbria, England, have been opposed for a number of reasons, including aesthetics, by some sectors of the population.
[128][129]
Many
wind power companies work with local communities to reduce
environmental and other concerns associated with particular wind farms.
[130][131][132][133] In other cases there is
direct community ownership of wind farm projects. Appropriate government consultation, planning and approval procedures also help to minimize environmental risks.
[8][134][135] Some may still object to wind farms
[101] but, according to
The Australia Institute, their concerns should be weighed against the need to address the threats posed by
climate change and the opinions of the broader community.
[136]
In
America, wind projects are reported to boost local tax bases, helping
to pay for schools, roads and hospitals. Wind projects also revitalize
the economy of rural communities by providing steady income to farmers
and other landowners.
[70]
In the UK, both the
National Trust and the
Campaign to Protect Rural England have expressed concerns about the effects on the rural landscape caused by inappropriately sited wind turbines and wind farms.
[137][138]
Some wind farms have become tourist attractions. The
Whitelee Wind Farm Visitor Centre has an exhibition room, a learning hub, a café with a viewing deck and also a shop. It is run by the
Glasgow Science Centre.
[139]
In
Denmark, a loss-of-value scheme gives people the right to claim
compensation for loss of value of their property if it is caused by
proximity to a wind turbine. The loss must be at least 1% of the
property’s value.
[140]
There
have been numerous reports of those living close to wind turbines
suffering adverse health effects from noise, vibration and shadow
flicker, and in 2009 New York Paediatrician, Dr. Nina Pierpont, claimed
to have identified an effect for which she coined the term "Wind Turbine
Sydrome".
[141]
An industry commissioned review of the current research on the possible
health effects of wind turbine noise and vibration reported in 2010
that, "the sound (including subaudible sound) is not unique, and does
not pose a risk to human health. Although the sound may cause
‘annoyance’ for some people, this in itself is not an adverse health
effect." The findings of the report have, however, been questioned on a
number of grounds including; that the reviewing group did not include an
epidemiologist, usually a given for assessing potential environmental
health hazards, and that there was no clear description of the methods
the researchers used to search for available research, nor how they
rated the quality of the research.
[142] In October 2010 The Society for Wind Vigilance held an international symposium concerning the subject.
[143]
A study on wind farm noise published in 2012 by The US state of
Massachusetts reported that people are annoyed by sound from wind
turbines at far lower sound levels than they are by noises from
railroads, aircraft, or road traffic. The study found the percentage of
respondents who found noise levels highly annoying rose quickly as sound
levels increased above about
37dbA (about the level of a conversation).
[144]
Small-scale wind power
Small-scale
wind power is the name given to wind generation systems with the
capacity to produce up to 50 kW of electrical power.
[145] Isolated communities, that may otherwise rely on
diesel
generators, may use wind turbines as an alternative. Individuals may
purchase these systems to reduce or eliminate their dependence on grid
electricity for economic reasons, or to reduce their
carbon footprint. Wind turbines have been used for household electricity generation in conjunction with
battery storage over many decades in remote areas.
[21]
Grid-connected domestic wind turbines may use
grid energy storage,
thus replacing purchased electricty with locally produced power when
available. The surplus power produced by domestic microgenerators can,
in some jurisdictions, be fed into the network and sold to the utility
company, producing a retail credit for the microgenerators' owners to
offset their energy costs.
[146][147]
Off-grid system users can either adapt to intermittent power or use batteries,
photovoltaic
or diesel systems to supplement the wind turbine. Equipment such as
parking meters, traffic warning signs, street lighting, or wireless
Internet gateways may be powered by a small wind turbine, possibly
combined with a photovoltaic system, that charges a small battery
replacing the need for a connection to the power grid.
[148]
In
locations near or around a group of high-rise buildings, wind shear
generates areas of intense turbulence, especially at street-level.
[149]
The risks associated with mechanical or catastrophic failure have thus
plagued urban wind development in densely populated areas, rendering the
costs of insuring urban wind systems prohibitive.
[150]
Moreover, quantifying the amount of wind in urban areas has been
difficult, as little is known about the actual wind resources of towns
and cities.
[151]
A
Carbon Trust
study into the potential of small-scale wind energy in the UK,
published in 2010, found that small wind turbines could provide up to
1.5 terawatt hours (TW·h) per year of electricity (0.4% of total UK
electricity consumption), saving 0.6 million tonnes of carbon dioxide
(Mt CO2) emission savings. This is based on the assumption that 10% of
households would install turbines at costs competitive with grid
electricity, around 12 pence (US 19 cents) a kW·h.
[152] A report prepared for the UK's government-sponsored
Energy Saving Trust
in 2006, found that home power generators of various kinds could
provide 30 to 40 per cent of the country's electricity needs by 2050.
[153]
Distributed generation from
renewable resources is increasing as a consequence of the increased awareness of
climate change. The electronic interfaces required to connect renewable generation units with the
utility system can include additional functions, such as the active filtering to enhance the power quality.
[154]
See also
Notes
- ^
For example, a 1 MW turbine with a capacity factor of 35% will not
produce 8,760 MW·h in a year (1 × 24 × 365), but only 1 × 0.35 × 24 ×
365 = 3,066 MW·h, averaging to 0.35 MW.
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- ^ Olson, William (15 February 2010). "An Urban Experiment in Renewable Energy". Retrieved 8 March 2010.
- ^ "Windy Cities? New research into the urban wind resource". Carbontrust.co.uk. Retrieved 29 August 2010.
- ^ "Smale scale wind energy". Carbontrust.co.uk. Retrieved 11 April 2012.
- ^ Hamer, Mick (21 January 2006). "The rooftop power revolution". New Scientist (Reed Business Information Ltd.) (2535). Retrieved 11 April 2012.
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External links [[PASTING TABLES IS NOT SUPPORTED]]
[[PASTING TABLES IS NOT SUPPORTED]] [[PASTING TABLES IS NOT SUPPORTED]]
[[PASTING TABLES IS NOT SUPPORTED]] [[PASTING TABLES IS NOT SUPPORTED]]
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