Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Wind Power shopping experience:
1. Compare - without doubt the biggest advantage that the Wind Power offers shoppers today is the ability to compare thousands of Wind Power at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.
2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about
3. Testimonials - don't know anybody that has bought a Wind Power? Wrong! If the Wind Power is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.
4. Questions - Got a question about Wind Power then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....
5. Reputation - Never heard of the company selling Wind Power? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Wind Power and build up a picture of their reputation for sales, returns, customer service, delivery etc.
6. Returns - still worried that even after all of the above your Wind Power wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.
7. Feedback - happy with your Wind Power then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.
8. Security - check for the yellow padlock on the Wind Power site before you buy, and the s after http:/ /i.e. https:// = a secure site
9. Contact - got a question about Wind Power, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.
10. Payment - ready to pay for your Wind Power, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.
. This 3 bladed turbine is the most common design of modern wind turbines.
Wind power is the conversion of wind energy into more useful forms, such as electricity, using wind turbines. At the end of 2006, worldwide capacity of wind-powered generators was 73.9 gigawatts; although it currently produces just over 1% of world-wide electricity use, World Wind Energy Association Statistics, it accounts for approximately 20% of electricity production in Wind power in Denmark, 9% in
Wind power in Spain, and 7% in Wind power in Germany. European wind companies grow in U.S. Globally, wind power generation more than quadrupled between 2000 and 2006. WWEA
Most modern wind power is generated in the form of electricity by converting the rotation of
wind turbine blades into electrical current by means of an
electrical generator. In windmills (a much older technology), wind energy is used to turn mechanical machinery to do physical work, such as crushing grain or pumping water.
Wind power is used in large scale
wind farms for national electrical grids as well as in small individual turbines for providing electricity to rural residences or grid-isolated locations.
Wind energy is plentiful, renewable energy, widely distributed, clean, and reduces toxic atmospheric and
greenhouse gas emissions if used to replace fossil-fuel-derived electricity. The
Intermittent power sources of wind seldom creates problems when using wind power at low to moderate penetration levels.http://www.ieawind.org/AnnexXXV/Meetings/Oklahoma/IEA%20SysOp%20GWPC2006%20paper_final.pdf IEA Wind Summary Paper,
Design and Operation of Power Systems with Large Amounts of Wind Power, September 2006
Wind energy
There is an estimated 50 to 100 times more wind energy than plant biomass energy available on Earth. Mapping the global wind power resource Biomass Resources for Energy and Industry Most of this wind energy can be found at high altitudes where continuous wind speeds of over 160 km/h (100 mph) occur. Eventually, the wind energy is converted through friction into diffuse heat throughout the Earth's surface and the atmosphere.
The origin of wind is complex. The Earth is unevenly heated by the sun resulting in the Geographic poles receiving less energy from the sun than the equator does. Also the dry land heats up (and cools down) more quickly than the seas do. The differential heating powers a global convection#Atmospheric convection system reaching from the Earth's surface to the stratosphere which acts as a virtual ceiling.
Wind variability and turbine power
.
The power in the wind can be extracted by allowing it to blow past moving wings that exert torque on a rotor. The amount of
Power (physics) transferred is directly proportional to the density of the air, the area swept out by the rotor, and the cube of the wind speed.
The power P available in the wind is given by:
P = \begin{matrix}\frac{1}{2}\end{matrix}\alpha\rho\pi r^2 v^3,
where P = power in watts, alpha = energy efficiency constant, rho = mass density of air in kilograms per cubic meter, r = radius of the wind turbine in meters, and v = velocity of the air in meters per second.
The
mass flow rate of air that travels through the swept area of a wind turbine varies with the wind speed and air density. As an example, on a cool 15 °C (59 °F) day at sea level, air density is 1.225 kilograms per cubic metre. An 8 m/s breeze blowing through a 100 meter diameter rotor would move almost 77,000 kilograms of air per second through the swept area.
The
kinetic energy of a given mass varies with the square of its velocity. Because the mass flow increases linearly with the wind speed, the wind power available to a wind turbine increases as the cube of the wind speed. The power of the example breeze above through the example rotor would be about 2.5 megawatts.
As the wind turbine extracts energy from the air flow, the air is slowed down, which causes it to spread out and diverts it around the wind turbine to some extent.
Albert Betz, a German physicist, determined in 1919 (see
Betz' law) that a wind turbine can extract at most 59% of the energy that would otherwise flow through the turbine's cross section. The Betz limit applies regardless of the design of the turbine.s.
Windiness 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 climatology 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 distribution model most frequently used to model wind speed climatology is a two-parameter Weibull distribution because it is able to conform to a wide variety of distribution shapes, from Gaussian to exponential. The
Rayleigh distribution model, an example of which is shown plotted against an actual measured dataset, is a specific form of the Weibull function in which the shape parameter equals 2, and very closely mirrors the actual distribution of hourly wind speeds at many locations.
]Because so much power is generated by higher windspeed, much of the average power available to a windmill comes in short bursts. The 2002 Lee Ranch sample is telling; half of the energy available arrived in just 15% of the operating time. The consequence is that wind energy does not have as consistent an output as fuel-fired power plants; utilities that use wind power must provide backup generation or grid power reception capability for times that the wind is weak.
Since wind speed is not constant, a wind generator's annual energy production is never as much as its nameplate rating 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. A well-sited wind generator will have a capacity factor of about 35%. This compares to a typical capacity factors of 90% for nuclear plants (like wind farms, they have negligible fuel cost, and are therefore often run at maximum capacity with the load following relegated to other plants).{{cite web | last = Nuclear Energy Institute
| title = Nuclear Facts
| url = http://www.nei.org/doc.asp?catnum=2&catid=106
| accessdate = 2006-07-23 -->
The lower values of 70% for coal plants and 30% for oil plants reflect a throttling-back of plants with high cost fuel in times of low demand.
When comparing the size of wind turbine plants to fueled power plants, it is important to note that 1000 kW of wind-turbine potential power would be expected to produce as much energy in a year as approximately 500 kW of coal-fired generation. Though the short-term (hours or days) output of a wind-plant is not completely predictable, the annual output of energy tends to vary only a few percent points between years.
When storage, such as with
Pumped-storage hydroelectricity, or other forms of generation are used to "shape" wind power (by assuring constant delivery reliability), commercial delivery represents a cost increase of about 25%, yielding viable commercial performance. Electricity consumption can be adapted to production variability to some extent with Energy Demand Management and smart meters that offer variable market pricing over the course of the day. For example, municipal water pumps that feed a water tower do not need to operate continuously and can be restricted to times when electricity is plentiful and cheap. Consumers could choose when to run the dishwasher or charge an electric vehicle (PHEV or EV), making it very convenient. PHEV/EV's are likely to be a very important source of demand management, which would mostly charge at night when wind power is most likely to be surplus, and whose charging could be scheduled in an automated fashion for periods of greatest wind output.
Turbine placement
As a general rule, wind generators are practical where the average wind speed is 10 mph (16 km/h or 4.5 m/s) or greater. Usually sites are pre-selected on basis of a
wind atlas, and validated with wind measurements. Obviously,
meteorology plays an important part in determining possible locations for wind parks, though it has great accuracy limitations. Meteorological wind data is not usually sufficient for accurate siting of a large wind power project. Site Specific Meteorological Data is crucial to determining site potential. An 'ideal' location would have a near constant flow of non-turbulent wind throughout the year and would not suffer too many sudden powerful bursts of wind. An important turbine siting factor is access to local demand or
electric power transmission capacity.
The most crucial step in the development of a potential wind site is the collection of accurate and verifiable wind speed and direction data as well as other site parameters. Meteorological Tower Installation To collect wind data a Meteorological Tower is installed at the potential site with instrumentation installed at various heights along the tower. All towers include anemometers to determine the wind speed and wind vanes to determine the direction. The towers generally vary in height from 30 to 60 meters. The towers primarily used in determining site feasibility for potential wind farms are guyed steel-pipe structures which are left to collect data for one to two years and then usually disassembled. Data is collected by a data logging device which stores and transmits data to a server where it is analyzed.
The wind blows faster at higher altitudes because of the reduced influence of drag of the surface (sea or land) and the reduced viscosity of the air. The increase in velocity with altitude is most dramatic near the surface and is affected by topography, surface roughness, and upwind obstacles such as trees or buildings. Typically, the increase of wind speeds with increasing height follows a logarithmic profile that can be reasonably approximated by the
wind profile power law, using an exponent of 1/7th, which predicts that wind speed rises proportionally to the seventh root of altitude. Doubling the altitude of a turbine, then, increases the expected wind speeds by 10% and the expected power by 34% (calculation: increase in power = (2.0) ^(3/7) – 1 = 34%).
Wind farms or wind parks often have many turbines installed. Since each turbine extracts some of the energy of the wind, it is important to provide adequate spacing between turbines to avoid excess energy loss. Where land area is sufficient, turbines are spaced three to five rotor diameters apart perpendicular to the prevailing wind, and five to ten rotor diameters apart in the direction of the prevailing wind, to minimize efficiency loss. The "wind park effect" loss can be as low as 2% of the combined
nameplate rating of the turbines.
Utility-scale wind turbine generators have minimum temperature operating limits which restrict the application in areas that routinely experience temperatures less than −20 °C. Wind turbines must be protected from ice accumulation, which can make anemometer readings inaccurate and which can cause high structure loads and damage. Some turbine manufacturers offer low-temperature packages at a few percent extra cost, which include internal heaters, different lubricants, and different alloys for structural elements, to make it possible to operate the turbines at lower temperatures. If the low-temperature interval is combined with a low-wind condition, the wind turbine will require station service power, equivalent to a few percent of its output rating, to maintain internal temperatures during the cold snap. For example, the
St. Leon, Manitoba, Manitoba project has a total rating of 99 MW and is estimated to need up to 3 MW (around 3% of capacity) of station service power a few days a year for temperatures down to −30 °C. This factor affects the economics of wind turbine operation in cold climates.
Onshore
Onshore turbine installations in hilly or mountainous regions tend to be on ridgelines generally three kilometers or more inland from the nearest shoreline. This is done to exploit the so-called topographic acceleration. The hill or ridge causes the wind to accelerate as it is forced over it. The additional wind speeds gained in this way make large differences to the amount of energy that is produced. Great attention must be paid to the exact positions of the turbines (a process known as micro-siting) because a difference of 30m can sometimes mean a doubling in output. Local winds are often monitored for a year or more with anemometers and detailed wind maps constructed before wind generators are installed.
For smaller installations where such data collection is too expensive or time consuming, the normal way of prospecting for wind-power sites is to directly look for trees or vegetation that are permanently "cast" or deformed by the prevailing winds. Another way is to use a wind-speed survey map, or historical data from a nearby meteorological station, although these methods are less reliable.
Wind farm siting can sometimes be highly controversial, particularly as the hilltop, often coastal sites preferred are often picturesque and environmentally sensitive (for instance, having substantial bird life). Local residents in a number of potential sites have strongly opposed the installation of wind farms, and political support has resulted in the blocking of construction of some installations.{{cite news|date = [2006-04-05 |accessdate = 2006-08-18 -->
Near-Shore
Near-Shore turbine installations are generally considered to be inside a zone that is on land within three kilometers of a shoreline or on water within ten kilometers of land. These areas tend to be windy and are good sites for turbine installation, because a primary source of wind is convection caused by the differential heating and cooling of land and sea over the cycle of day and night. Wind speeds in these zones share the characteristics of both onshore and offshore wind, depending on the prevailing wind direction.
Common issues that are shared within near-shore wind development zones are aviary (including bird migration and nesting), aquatic habitat, transportation (including shipping and boating) and visual aesthetics. Local residents in some potential sites have strongly opposed the installation of wind farms due to these concerns.
Offshore
Offshore wind development zones are generally considered to be ten kilometers or more from land. Offshore wind turbines are less obtrusive than turbines on land, as their apparent size and noise can be mitigated by distance. Because water has less surface roughness than land (especially deeper water), the average wind speed is usually considerably higher over open water. Capacity factors (utilisation rates) are considerably higher than for onshore and near-shore locations which allows offshore turbines to use shorter towers, making them less visible.
In stormy areas with extended shallow continental shelves (such as
Denmark), turbines are practical to install — Denmark's wind generation provides about 18% of total electricity production in the country, with many offshore windfarms. Denmark plans to increase wind energy's contribution to as much as half of its electrical supply.
Locations have begun to be developed in the Great Lakes - with one project by Trillium Power approximately 20 km from shore and over 700 MW in size. Ontario, Canada is aggressively pursuing wind power development and has many onshore wind farms and several proposed near-shore locations but presently only one offshore development.
In most cases offshore environment is more expensive than onshore. Offshore towers are generally taller than onshore towers once the submerged height is included, and offshore foundations are more difficult to build and more expensive. Power transmission from offshore turbines is generally through
submarine cable, which is more expensive to install than cables on land, and may use high voltage direct current operation if significant distance is to be covered — which then requires yet more equipment. Offshore saltwater environments can also raise maintenance costs by corroding the towers, but fresh-water locations such as the Great Lakes do not. Repairs and maintenance are usually much more difficult, and generally more costly, than on onshore turbines. Offshore saltwater wind turbines are outfitted with extensive corrosion protection measures like coatings and cathodic protection, which may not be required in fresh water locations.
While there is a significant market for small land-based windmills, offshore wind turbines have recently been and will probably continue to be the largest wind turbines in operation, because larger turbines allow for the spread of the high
fixed costs involved in offshore operation over a greater quantity of generation, reducing the average cost. For similar reasons, offshore
wind farms tend to be quite large—often involving over 100 turbines—as opposed to onshore wind farms which can operate competitively even with much smaller installations.
Airborne
Wind turbines might also be flown in high speed winds at altitude, although no such systems currently exist in the marketplace. An Ontario (Canada) company, Magenn Power, Inc., is attempting to commercialize tethered aerial turbines suspended with helium
The Italian project called "Kitegen" uses a prototype vertical-axis wind turbine. It is an innovative plan (still in the construction phase) that consists of one wind farm with a vertical spin axis, and employs kites to exploit high-altitude winds. The Kite Wind Generator (KWG) or KiteGen is claimed to eliminate all the static and dynamic problems that prevent the increase of the power (in terms of dimensions) obtainable from the traditional horizontal-axis wind turbine generators.A number of other designs for vertical-axis turbines have been developed or proposed, including small scale commercial or pilot installations. However, vertical-axis turbines remain a commercially unproven technology.
Utilization
Large scale
{| class="wikitable" style="float: right; margin-left: 10px"! colspan="5" align=center style="background-color: #cfb;" | Installed windpower capacity (MW)|-! style="background-color: #cfb;" | Rank! style="background-color: #cfb;" | Nation! style="background-color: #cfb;" align=right | 2005! style="background-color: #cfb;" align=right | 2006! style="background-color: #cfb;" align=right | Latest|-| align=right | 1 ||
Wind power in Germany || align=right | 18,415 || align=right | 20,622 || align=right | 21,283|-| align=right | 2 || Wind power in Spain || align=right | 10,028 || align=right | 11,615 || align=right | 12,801|-| align=right | 3 ||
Wind power in the United States || align=right | 9,149 || align=right | 11,603 || align=right | 12,634|-| align=right | 4 || Wind power in India || align=right | 4,430 || align=right | 6,270 || align=right | 7,231|-| align=right | 5 || Wind power in Denmark || align=right | 3,136 || align=right | 3,140 || align=right ||-| align=right | 6 || China || align=right | 1,260 || align=right | 2,604 || align=right | 2,956|-| align=right | 7 || Italy || align=right | 1,718 || align=right | 2,123 || align=right ||-| align=right | 8 || Wind power in the United Kingdom || align=right | 1,332 || align=right | 1,963 || align=right | 2,191|-| align=right | 9 || Renewable energy in Portugal || align=right | 1,022 || align=right | 1,716 || align=right | 1,874|-| align=right | 10 ||
List of wind farms in Canada || align=right | 683 || align=right | 1,459 || align=right | 1,670|-| align=right | 11 || France || align=right | 757 || align=right | 1,567 || align=right ||-| align=right | 12 || Netherlands || align=right | 1,219 || align=right | 1,560 || align=right ||-| align=right | 13 || Japan || align=right | 1,061 || align=right | 1,394 || align=right ||-| align=right | 14 || Austria || align=right | 819 || align=right | 965 || align=right ||-| align=right | 15 ||
Wind power in Australia || align=right | 708 || align=right | 817 || align=right ||-| align=right | 16 || Greece || align=right | 573 || align=right | 746 || align=right | 795|-| align=right | 17 || Ireland || align=right | 496 || align=right | 745 || align=right | 866|-| align=right | 18 || Sweden || align=right | 510 || align=right | 572 || align=right ||-| align=right | 19 || Norway || align=right | 267 || align=right | 314 || align=right ||-| align=right | 20 || Brazil || align=right | 29 || align=right | 237 || align=right ||-| align=right | 21 || Egypt || align=right | 145 || align=right | 230 || align=right | 580|-| align=right | 22 || Belgium || align=right | 167 || align=right | 193 || align=right ||-| align=right | 23 || Taiwan || align=right | 104 || align=right | 188 || align=right ||-| align=right | 24 || South Korea || align=right | 98 || align=right | 173 || align=right ||-| align=right | 25 || New Zealand || align=right | 169 || align=right | 171 || align=right | 322|-| align=right | 26 || Poland || align=right | 83 || align=right | 153 || align=right | 216|-| align=right | 27 || Morocco || align=right | 64 || align=right | 124 || align=right ||-| align=right | 28 || Mexico || align=right | 3 || align=right | 88 || align=right ||-| align=right | 29 || Finland || align=right | 82 || align=right | 86 || align=right | 107|-| align=right | 30 || Ukraine || align=right | 77 || align=right | 86 || align=right ||-| align=right | 31 || Costa Rica || align=right | 71 || align=right | 74 || align=right ||-| align=right | 32 ||
Hungary ] || align=right | 23 || align=right | 48 || align=right ||-| align=right | || Rest of Europe || align=right | 129 || align=right | 163 || align=right ||-| align=right | || Rest of Americas || align=right | 109 || align=right | 109 || align=right ||-| align=right | || Rest of Asia || align=right | 38 || align=right | 38 || align=right ||-| align=right | || Rest of Africa & Middle East || align=right | 31 || align=right | 31 || align=right ||-| align=right | || Rest of Oceania || align=right | 12 || align=right | 12 || align=right ||-|! style="background-color: #cfb;" | World total (MW)| align=right style="background-color: #cfb;" |
59,091 || align=right style="background-color: #cfb;" |
74,223 || align=right style="background-color: #cfb;" |
79,341|}
There are many thousands of wind turbines operating, with a total capacity of 73,904 MW of which Europe accounts for 65% (2006). The average output of one megawatt of wind power is equivalent to the average electricity consumption of about 250 American households. Wind power was the most rapidly-growing means of alternative electricity generation at the turn of the century and world wind generation capacity more than quadrupled between 2000 and 2006. 81% of wind power installations are in the US and Europe, but the share of the top five countries in terms of new installations fell from 71% in 2004 to 55% in 2005.
By 2010, the World Wind Energy Association expects 160GW of capacity to be installed worldwide, up from 73.9GW at the end of 2006, implying an anticipated net growth rate of more than 21% per year.
Germany,
Spain, the United States, India, and Denmark have made the largest investments in wind generated electricity. Denmark is prominent in the manufacturing and use of wind turbines, with a commitment made in the 1970s to eventually produce half of the country's power by wind.
Denmark generates over 20% of its electricity with wind turbines, the highest percentage of any country and is fifth in the world in total power generation (which can be compared with the fact that Denmark is 56th on the
List of countries by electricity consumption). Denmark and Germany are leading exporters of large (0.66 to 5 MW) turbines.
Wind accounts for 1% of the total electricity production on a global scale (2005). Germany is the leading producer of wind power with 28% of the total world capacity in 2006 (7.3% of German electricity); the official target is that by 2010, renewable energy will meet 12.5% of German electricity needs — it can be expected that this target will be reached even earlier. Germany has 18,600 wind turbines, mostly in the north of the country — including three of the biggest in the world, constructed by the companies
Enercon (6 MW), Multibrid (5 MW) and Repower (5 MW). Germany's
Schleswig-Holstein province generates 36% of its power with wind turbines.
Spain and the United States are next in terms of installed capacity. In 2005, the government of Spain approved a new national goal for installed wind power capacity of 20,000 MW by 2012. According to trade journal Windpower Monthly; however, in 2006 they abruptly halted subsidies and price supports for wind power. According to the American Wind Energy Association, wind generated enough electricity to power 0.4% (1.6 million households) of total electricity in US, up from less than 0.1% in 1999. In 2005, both Germany and Spain have produced more electricity from wind power than from hydropower plants.
US Department of Energy studies have concluded wind harvested in just three of the fifty U.S. states could provide enough electricity to power the entire nation, and that offshore wind farms could do the same job.
In recent years, the United States has added more wind energy to its grid than any other single country, and capacity is expected to grow by 3 gigawatts (3,000 megawatts) in 2007. Texas has become the leader in Wind Energy production, far surpassing
California. In 2007, the state expects to add 2 gigawatts to raise its existing capacity to approximately 4.5 gigawatts. Iowa and Minnesota are expected to reach the 1 gigawatt mark by the end of 2007. http://awea.org/projects Wind power generation in the U.S. was up 31.8% in February, 2007 from February, 2006.http://www.eia.doe.gov/cneaf/electricity/epm/epm_sum.html
India ranks 4th in the world with a total wind power capacity of 6,270 MW in 2006. Wind power generates 3% of all electricity produced in India. The World Wind Energy Conference in New Delhi in November 2006 has given additional impetus to the Indian wind industry. The windfarm near Muppandal, India, provides an impoverished village with energy for work.{{cite web] is one of the world's largest wind turbine manufacturers. Suzlon Energy
In December 2003,
General Electric installed the world's largest offshore wind turbines in Ireland, and plans are being made for more such installations on the west coast, including the possible use of floating turbines.
On
August 15, 2005, People's Republic of China announced it would build a 1000-megawatt wind farm in Hebei for completion in 2020. China reportedly has set a generating target of 20,000 MW by 2020 from renewable energy sources — it says indigenous wind power could generate up to 253,000 MW. Following the World Wind Energy Conference in November 2004, organised by the Chinese and the World Wind Energy Association, a Chinese renewable energy law was adopted. In late 2005, the Chinese government increased the official wind energy target for the year 2020 from 20 GW to 30 GW.Lema, Adrian and Kristian Ruby, ”Between fragmented authoritarianism and policy coordination: Creating a Chinese market for wind energy”, Energy Policy, Vol. 35, Isue 7, July 2007
Mexico recently opened La Venta II wind power project as an important step in reducing Mexico's consumption of fossil fuels. The project (88MW) the first of its kind in Mexico, will provide 13 percent of the electricity needs of the state of Oaxaca and by 2012 will have a capacity of 3500 MW.
Another growing market is Brazil, with a wind potential of 143 GW. The federal government has created an incentive program, called Proinfa, to build production capacity of 3300 MW of renewable energy for 2008, of which 1422 MW through wind energy. The program seeks to produce 10% of Brazilian electricity through renewable sources. Brazil produced 320 TWh in 2004.
France recently announced a very ambitious target of 12 500 MW installed by 2010., Tamilnadu in India
Over the 7 years from 2000-2006, Canada experienced rapid growth of wind capacity — moving from a total installed capacity of 137 MW to 1,451 MW, and showing a growth rate of 38% and rising. Particularly rapid growth has been seen in 2006, with total capacity growing to 1,451 MW by December, 2006, doubling the installed capacity from the 684 MW at end-2005. This growth was fed by provincial measures, including installation targets, economic incentives and political support. For example, the government of the Canadian province of
Ontario announced on
21 March 2006 that it will introduce a feed-in tariff for wind power, referred to as 'Standard Offer Contracts', which may boost the wind industry across the province. In the Canadian province of Quebec, the state-owned hydroelectric utility plans beside current wind farm projects to purchase an additional 2000 MW by 2013.
Wind power in Europe
{| class="wikitable" style="foat right" margin-left: 10px"! colspan="5" align=center style="background-color: #cfb;" | Wind Power in Europe 2006 (MW)|-! style="background-color: #cfb;" | No! align=left style="background-color: #cfb;" | Country! align=right style="background-color: #cfb;" | Addition! align=right style="background-color: #cfb;" | Total
|-| align=right | 1 ||
Wind power in Germany || align=right | 2 233 || align=right |
Renewable energy in Germany|-| align=right | 2 ||
Wind power in Spain || align=right | 1 587 || align=right | 11 615|-| align=right | 3 || Wind power in France || align=right | 810 || align=right | 1 567|-| align=right | 4 ||
Wind power in Portugal || align=right | 694 || align=right | 1 716|-| align=right | 5 || Wind power in the United Kingdom || align=right | 634 || align=right | 1 963|-| align=right | 6 || Italy || align=right | 417 || align=right | 2 123|-| align=right | 7 || Netherlands || align=right | 356 || align=right | 1 560|-| align=right | 8 || Ireland || align=right | 250 || align=right | 745|-| align=right | 9 || Greece || align=right | 173 || align=right | 746|-| align=right | 10 || Austria || align=right | 146 || align=right | 965|-| align=right | 11 || Poland || align=right | 69 || align=right | 152|-| align=right | 12 || Sweden || align=right | 62 || align=right | 572|-| align=right | 13 || Lithuania || align=right | 49 || align=right | 55|-| align=right | 14 || Hungary || align=right | 43 || align=right | 61|-| align=right | 15 || Belgium || align=right | 26 || align=right | 193|-| align=right | 16 || Czech Republic || align=right | 22 || align=right | 50|-| align=right | 17 || Bulgaria || align=right | 22 || align=right | 32|-| align=right | 18 ||
Wind power in Denmark || align=right | 11 || align=right | 3 140|-| align=right | 19 || Finland || align=right | 4 || align=right | 86|-| align=right | 20 || Romania || align=right | 1 || align=right | 3|-| align=right | 21 || Luxembourg || align=right | 0 || align=right | 35|-| align=right | 22 || Estonia || align=right | 0 || align=right | 32|-| align=right | 23 || Latvia || align=right | 0 || align=right | 27|-| align=right | 24 || Slovenia || align=right | 0 || align=right | 5|-| align=right | 25 || Slovakia || align=right | 0 || align=right | 0|-| align=right | 26 || Cyprus || align=right | 0 || align=right | 0|-| align=right | 27 || Malta || align=right | 0 || align=right | 0|-! colspan="2" align=left style="background-color: #cfb;" | EU27 (MW)| align=right style="background-color: #cfb;" |
7 609 || align=right style="background-color: #cfb;" |
48 061|-| align=right | 28 || Norway || align=right | 47 || align=right | 314|-! colspan="2" align=left style="background-color: #cfb;" | Europe (MW)| align=right style="background-color: #cfb;" |
7 708 || align=right style="background-color: #cfb;" |
48 545|-----| colspan=9 align=left | ref in discussion|}
Small scale
and runs various 12 volt appliances within the building on which it is installed.
Small Wind is defined as wind generation systems with capacities of 100 kW or less and are usually used to power homes, farms, and small businesses. Individuals purchase these systems to reduce or eliminate their electricity bills, to avoid the unpredictability of natural gas prices, or simply to generate their own clean power.
Wind turbines have been used for household electricity generation in conjunction with Battery (electricity) storage over many decades in remote areas, but increasingly, U.S. consumers are choosing to purchase grid-connected turbines in the 1 to 10 kilowatt range to power their whole homes. Household generator units of more than 1 kW are now functioning in several countries, and in every state in the U.S.
To compensate for the varying power output, grid-connected wind turbines may utilise some sort of
grid energy storage. Off-grid systems either adapt to intermittent power or use
photovoltaic or diesel systems to supplement the wind turbine.
Wind turbines range from small four hundred watt generators for residential use to several megawatt machines for wind farms and offshore. The small ones sometimes, but not always, have direct drive generators, direct current output, aeroelastic blades, lifetime bearings and use a vane to point into the wind; while the larger ones generally have geared power trains, alternating current output, flaps and are actively pointed into the wind. Direct drive generators and aeroelastic blades for large wind turbines are being researched and direct current generators are sometimes used.
In urban locations, where it is difficult to obtain predictable or large amounts of wind energy, smaller systems may still be used to run low power equipment. Distributed generation from rooftop mounted wind turbines can also alleviate power distribution problems, as well as provide resilience to power failures. Equipment such as parking meters or wireless internet gateways may be powered by a wind turbine that charges a small battery, replacing the need for a connection to the power grid and/or maintaining service despite possible power grid failures.
While installing a small wind turbine on a roof (rather than a tall tower elsewhere on a property) can be done successfully, there are a few inherent issues that this type of installation faces: Whether the roof can support the turbine's weight, how the building tolerates the vibrations from the spinning rotor, and the turbulence caused by the roof ledge and the resulting unpredictability in wind patterns.
Small scale turbines for residential-scale use are available that are approximately 7 feet (2 m) to in diameter and produce electricity at a rate of 900 watts to 10,000 watts at their tested wind speed. Some units are designed to be very lightweight, e.g. 16 kilograms (35 lb), allowing rapid response to wind gusts typical of urban settings and easy mounting much like a television antenna. It is claimed that they are inaudible even a few feet under the turbine. Dynamic braking regulates the speed by dumping excess energy, so that the turbine continues to produce electricity even in high winds. The dynamic braking resistor may be installed inside the building to provide heat (during high winds when more heat is lost by the building, while more heat is also produced by the braking resistor). The proximal location makes low voltage (12 volt, or the like) energy distribution practical. An additional benefit is that owners become more aware of electricity consumption, possibly reducing their consumption down to the average level that the turbine can produce.
The American Wind Energy Association has released several studies on the small wind turbine market in the U.S. and abroad, showing that the U.S. continues to dominate the Small Wind industry. According to another organization, the World Wind Energy Association, it is difficult to assess the total number or capacity of small-scaled wind turbines, but in China alone, there are roughly 300,000 small-scale wind turbines generating electricity.
The dominant model on the market, especially in the United States, is the propeller-shaped "Horizontal Axis" type, which resembles the large, utility-scale turbines used in wind "farms." An alternative model is known as "Vertical Axis," and rotates like a top and can come in many different designs.
There have been a number of recent developments of mini-windmills which could be adapted to home use, including:
- The AeroTecture Wind turbine#Vertical axis AeroTecture
- The AeroVironment Architectural Wind Project 'Micro' wind turbines are coming to town, CNET, February 10, 2006, Martin LaMonica
- The piezoelectric windmill project
- The Swift home wind turbine. Swift Turbines The Swift project peaked in 2004 and has had some implementation difficulties while promising to be a low-noise/safe roof-mount/low-cost alternative Better Generation: Swift Rooftop wind energy system discussion
- The Motorwave micro-wind turbine Motorwind Lucien Gambarota: Alternative energy pioneer, CNN, 16 April 2007 Motorwind Turbines
Consumer guides are available to help potential customers learn about residential-scale wind systems, three of which are:
- "Small Wind Electric Systems: A U.S. Consumer's Guide" by the Dept. of Energy's Wind Powering America program
- "Wind Turbine Buyer's Guide" From Home Power Magazine
- "Apples & Oranges 2002: Choosing a Home-Sized Wind Generator"
Much more information is also available at the American Wind Energy Association's web site at:
- www.awea.org/smallwind
- FAQ: http://www.awea.org/smallwind/faq.html
- www.awea.org/smallwind/toolbox2/index.html
Wind power: key issues
Wind power can be a controversial issue, and several main areas of dispute are debated between supporters and opponents.
E70-4 in
Germany
Growth and cost trends
Global Wind Energy Council (GWEC) figures show that 2006 recorded an increase of installed capacity of 15,197 megawatts (MW), taking the total installed wind energy capacity to 74,223 MW, up from 59,091 MW in 2005. Despite constraints facing supply chains for wind turbines, the annual market for wind continued to increase at an estimated rate of 32% following the 2005 record year, in which the market grew by 41%. 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 2006 reaching €18 billion, or US$23 billion.
The countries with the highest total installed capacity are Wind power in Germany (20,621 MW), Wind power in Spain (11,615 MW), the USA (11,603 MW), India (6,270 MW) and Wind power in Denmark (3,136). Thirteen countries around the world can now be counted among those with over 1,000 MW of wind capacity. In terms of new installed capacity in 2006, the US leads with 2,454 MW, followed by Germany (2,233 MW), India (1,840 MW), Spain (1,587 MW), China (1,347 MW) and France (810 MW).
In 2004, wind energy cost one-fifth of what it did in the 1980s, and some expected that downward trend to continue as larger multi-megawatt
Wind turbine are mass-produced. However, installation costs have increased significantly in 2005 and 2006, and according to the major U.S. wind industry trade group, now average over US$1,600 per kilowatt, compared to $1200/kW just a few years before. A British Wind Energy Association report gives an average generation cost of onshore wind power of around 3.2 pence per kilowatt hour (2005). BWEA report on onshore wind costs Cost per unit of energy produced was estimated in 2006 to be comparable to the cost of new generating capacity in the United States for coal and natural gas: wind cost was estimated at $55.80 per MWh, coal at $53.10/MWh and natural gas at $52.50.http://www.eia.doe.gov/oiaf/ieo/pdf/0484(2006).pdf Energy Information Administration, "International Energy Outlook", 2006, p. 66. Other sources in various studies have estimated wind to be more expensive than other sources (see
Economics of new nuclear power plants, Clean coal, and Carbon capture and storage).
Most major forms of electricity generation are capital intensive, meaning that they require substantial investments at project inception, and low ongoing costs (generally for fuel and maintenance). This is particularly true for wind and hydro power, which have fuel costs close to zero and relatively low maintenance costs; in economic terms, wind power has an extremely low marginal cost and a high proportion of up-front capital costs. The estimated "cost" of wind energy per unit of production is generally based on average cost per unit, which incorporates the cost of construction, borrowed funds, return to investors (including cost of risk), estimated annual production, and other components. Since these costs are averaged over the projected useful life of the equipment, which may be in excess of twenty years, cost estimates per unit of generation are highly dependent on these assumptions. Figures for cost of wind energy per unit of production cited in various studies can therefore differ substantially. The cost of wind power also depends on several other factors, such as installation of power lines from the wind farm to the
national grid and the frequency of wind at the site in question.
Estimates for cost of production use similar methodologies for other sources of electricity generation. Existing generation capacity represents sunk costs, and the decision to continue production will depend on marginal costs going forward, not estimated average costs at project inception. For example, the estimated cost of new wind power capacity may be lower than that for "new coal" (estimated average costs for new generation capacity) but higher than for "old coal" (marginal cost of production for existing capacity). Therefore, the choice to increase wind capacity by building new facilities will depend on more complex factors than cost estimates, including the profile of existing generation capacity.
Research from a wide variety of sources in various countries shows that support for wind power is consistently between 70 and 80 per cent amongst the general public. Fact sheet 4: Tourism
Scalability
A key issue debated about wind power is its ability to scale to meet a substantial portion of the world's energy demand. There are significant economic, technical, and ecological issues about the large-scale use of wind power that may limit its ability to replace other forms of energy production. See, for example, the annual report of the Independent Electricity System Operator in Ontario, Canada . Most forms of electricity production also involve such trade-offs, and many are also not capable of replacing all other types of production for various reasons. A key issue in the application of wind energy to replace substantial amounts of other electrical production is Intermittent Power Sources; see the section below on Economics and Feasibility. At present, it is unclear whether wind energy will eventually be sufficient to replace other forms of electricity production, but this does not mean wind energy cannot be a significant source of clean electrical production on a scale comparable to or greater than other technologies, such as
hydropower. Most electrical grids use a mix of different generation types (baseload generating capacity and peaking capacity) to match demand cycles by attempting to match the variable nature of demand to the most economic form of production; with the exception of hydropower, most types of production capacity are not used for all production (hydropower usage is limited by the presence of appropriate geographical sites). For example, nuclear power is effective as a baseload technology, but cannot be easily varied in short timeframes, and gas turbine plants are most economically used as peaking capacity; coal generation is primarily considered appropriate for baseload generation with some capacity to cycle to meet demand.
A significant part of the debate about the potential for wind energy to substitute for other electric production sources is the level of penetration. With the exception of Denmark, no countries or electrical systems produce more than 10% from wind energy, and most are below 2% (of course, this is in large part because wind power is a relatively new technology, with the vast majority of installations having taken place within the last 10 years). While the feasibility of integrating much higher levels (beyond 25%) is debated, significantly more wind energy could be produced worldwide before these issues become significant. In Denmark, wind power now accounts for close to 20% of electricity productionhttp://www.windpower.org/en/stats/shareofconsumption.htm and a recent poll of Danes show that 90% want more wind power installed.http://www.windpower.org/composite-1172.htm
Theoretical potential
Wind's long-term theoretical potential is much greater than current world energy consumption. The most comprehensive study to date found the potential of wind power on land and near-shore to be 72 Watt (~171,000
Ton of oil equivalent), or over fifteen times the world's current energy use and 40 times the current electricity use. The potential takes into account only locations with Class 3 (mean annual wind speeds ≥ 6.9 m/s at 80 m) or better wind regimes, which includes the locations suitable for low-cost (0.03–0.04 $/kWh) wind power generation and is in that sense conservative. It assumes 6 turbines per square km for 77 m diameter, 1.5 MW-turbines on roughly 13% of the total global land area (though that land would also be available for other compatible uses such as farming). However, the authors are quick to point out that many practical barriers would need to be overcome to reach this theoretical capacity. The calculations of potential assumes a capacity factor of 48% and does not take into account the practicality of reaching the windy sites, of transmission (including 'choke' points), of competing land uses, of transporting power over large distances, or of switching to wind power.
To determine the more realistic
technical potential, it is essential to estimate how large a fraction of this land could be made available to wind power. In the 2001 IPCC report, it is assumed that a use of 4% – 10% of that land area would be practical.
Although the theoretical potential is vast, the amount of production that could be economically viable depends on a number of exogenous and endogenous factors, including the cost of other sources of electricity and the future cost of wind energy farms.
Offshore resources experience mean wind speeds about 90% greater than those on land, so offshore resources could contribute about seven times more energy than land. This number could also increase with higher altitude or airborne wind turbines.
Economics and feasibility
, in California. Developed during a period of tax incentives in the 1980s, this wind farm has more turbines than any other in the United States, producing about 125 MW. Wind Plants of California's Altamont Pass Considered largely obsolete, these turbines produce only a few tens of kilowatts each.
Wind energy in many jurisdictions receives some financial or other support to encourage its development. A key issue is the comparison to other forms of energy production, and their total cost. Two main points of discussion arise: direct
subsidy and externalities for various sources of electricity, including wind. Wind energy benefits from subsidies of various kinds in many jurisdictions, either to increase its attractiveness, or to compensate for subsidies received by other forms of production or which have significant negative externalities. Without the handsome tax incentives (also know as subsidies) in fact, almost no wind power installation is economically feasible at present.
Most forms of energy production create some form of negative externality: costs that are not paid by the producer or consumer of the good. For electric production, the most significant externality is pollution, which imposes costs on society in the form of increased health expenses, reduced agricultural productivity, and other problems. In addition,
carbon dioxide, a
greenhouse gas produced when fossil fuels are burned for electricity production, may impose even greater costs on society in the form of
global warming. Few mechanisms currently exist to impose (or
internalise) these external costs in a consistent way between various industries or technologies, and the total cost is highly uncertain. Other significant externalities can include national security expenditures to ensure access to fossil fuels, remediation of polluted sites, destruction of wild habitat, loss of scenery/tourism, etc.
Wind energy supporters argue that, once external costs and subsidies to other forms of electrical production are accounted for, wind energy is amongst the most cost-effective forms of electrical production. Critics argue that the level of required subsidies, the small amount of energy needs met, and the uncertain financial returns to wind projects — that is, the all-in cost of wind energy compared to other technologies - make it inferior to other energy sources. Intermittency and other characteristics of wind energy also have costs that may rise with higher levels of penetration, and may change the cost-benefit ratio.
- Conventional and nuclear power plants receive substantial direct and indirect governmental subsidies. If a comparison is made on total production costs (including subsidies), wind energy may or may not be competitive compared to other energy sources. If the full costs (environmental, health, etc.) are taken into account, wind energy may be competitive in more cases. Wind energy costs have generally decreased due to technology development and scale enlargement. However, the cost of other capital intensive generation technologies, such as nuclear and fossil fueled plants, is also subject to cost reductions due to economy of scale and technological improvements.
- Nuclear power plants generally receive special Price-Anderson Nuclear Industries Indemnity Act from the disasters they may cause, which prevents victims from recovering the cost of their continued health care from those responsible, even in the case of criminal malfeasance. In many cases, nuclear plants are owned directly by governments or substantially supported by them. In both cases, nuclear plants benefit from a lower cost of capital and lower perceived risk, as governments take on the risk charge directly. This is a form of indirect subsidy, although the size of this subsidy is difficult to ascertain precisely.
- To compete with traditional sources of energy, wind power often receives financial incentives. In the United States, wind power receives a tax credit for each kilowatt-hour produced; at 1.9 cents per kilowatt-hour 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 Wind Power Production Incentive 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.
- Many potential sites for wind farms are far from demand centers, requiri
. This 3 bladed turbine is the most common design of modern wind turbines.Wind power is the conversion of wind energy into more useful forms, such as electricity, using wind turbines. At the end of 2006, worldwide capacity of wind-powered generators was 73.9 gigawatts; although it currently produces just over 1% of world-wide electricity use, World Wind Energy Association Statistics, it accounts for approximately 20% of electricity production in Wind power in Denmark, 9% in Wind power in Spain, and 7% in Wind power in Germany. European wind companies grow in U.S. Globally, wind power generation more than quadrupled between 2000 and 2006. WWEA
Most modern wind power is generated in the form of electricity by converting the rotation of wind turbine blades into electrical current by means of an electrical generator. In windmills (a much older technology), wind energy is used to turn mechanical machinery to do physical work, such as crushing grain or pumping water.
Wind power is used in large scale wind farms for national electrical grids as well as in small individual turbines for providing electricity to rural residences or grid-isolated locations.
Wind energy is plentiful, renewable energy, widely distributed, clean, and reduces toxic atmospheric and greenhouse gas emissions if used to replace fossil-fuel-derived electricity. The Intermittent power sources of wind seldom creates problems when using wind power at low to moderate penetration levels.http://www.ieawind.org/AnnexXXV/Meetings/Oklahoma/IEA%20SysOp%20GWPC2006%20paper_final.pdf IEA Wind Summary Paper, Design and Operation of Power Systems with Large Amounts of Wind Power, September 2006
Wind energy
There is an estimated 50 to 100 times more wind energy than plant biomass energy available on Earth. Mapping the global wind power resource Biomass Resources for Energy and Industry Most of this wind energy can be found at high altitudes where continuous wind speeds of over 160 km/h (100 mph) occur. Eventually, the wind energy is converted through friction into diffuse heat throughout the Earth's surface and the atmosphere.
The origin of wind is complex. The Earth is unevenly heated by the sun resulting in the Geographic poles receiving less energy from the sun than the equator does. Also the dry land heats up (and cools down) more quickly than the seas do. The differential heating powers a global convection#Atmospheric convection system reaching from the Earth's surface to the stratosphere which acts as a virtual ceiling.
Wind variability and turbine power
.
The power in the wind can be extracted by allowing it to blow past moving wings that exert torque on a rotor. The amount of Power (physics) transferred is directly proportional to the density of the air, the area swept out by the rotor, and the cube of the wind speed.
The power P available in the wind is given by:
P = \begin{matrix}\frac{1}{2}\end{matrix}\alpha\rho\pi r^2 v^3,
where P = power in watts, alpha = energy efficiency constant, rho = mass density of air in kilograms per cubic meter, r = radius of the wind turbine in meters, and v = velocity of the air in meters per second.
The mass flow rate of air that travels through the swept area of a wind turbine varies with the wind speed and air density. As an example, on a cool 15 °C (59 °F) day at sea level, air density is 1.225 kilograms per cubic metre. An 8 m/s breeze blowing through a 100 meter diameter rotor would move almost 77,000 kilograms of air per second through the swept area.
The kinetic energy of a given mass varies with the square of its velocity. Because the mass flow increases linearly with the wind speed, the wind power available to a wind turbine increases as the cube of the wind speed. The power of the example breeze above through the example rotor would be about 2.5 megawatts.
As the wind turbine extracts energy from the air flow, the air is slowed down, which causes it to spread out and diverts it around the wind turbine to some extent. Albert Betz, a German physicist, determined in 1919 (see Betz' law) that a wind turbine can extract at most 59% of the energy that would otherwise flow through the turbine's cross section. The Betz limit applies regardless of the design of the turbine.s.
Windiness 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 climatology 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 distribution model most frequently used to model wind speed climatology is a two-parameter Weibull distribution because it is able to conform to a wide variety of distribution shapes, from Gaussian to exponential. The Rayleigh distribution model, an example of which is shown plotted against an actual measured dataset, is a specific form of the Weibull function in which the shape parameter equals 2, and very closely mirrors the actual distribution of hourly wind speeds at many locations.
]Because so much power is generated by higher windspeed, much of the average power available to a windmill comes in short bursts. The 2002 Lee Ranch sample is telling; half of the energy available arrived in just 15% of the operating time. The consequence is that wind energy does not have as consistent an output as fuel-fired power plants; utilities that use wind power must provide backup generation or grid power reception capability for times that the wind is weak.
Since wind speed is not constant, a wind generator's annual energy production is never as much as its nameplate rating 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. A well-sited wind generator will have a capacity factor of about 35%. This compares to a typical capacity factors of 90% for nuclear plants (like wind farms, they have negligible fuel cost, and are therefore often run at maximum capacity with the load following relegated to other plants).{{cite web | last = Nuclear Energy Institute
| title = Nuclear Facts
| url = http://www.nei.org/doc.asp?catnum=2&catid=106
| accessdate = 2006-07-23 -->
The lower values of 70% for coal plants and 30% for oil plants reflect a throttling-back of plants with high cost fuel in times of low demand.
When comparing the size of wind turbine plants to fueled power plants, it is important to note that 1000 kW of wind-turbine potential power would be expected to produce as much energy in a year as approximately 500 kW of coal-fired generation. Though the short-term (hours or days) output of a wind-plant is not completely predictable, the annual output of energy tends to vary only a few percent points between years.
When storage, such as with Pumped-storage hydroelectricity, or other forms of generation are used to "shape" wind power (by assuring constant delivery reliability), commercial delivery represents a cost increase of about 25%, yielding viable commercial performance. Electricity consumption can be adapted to production variability to some extent with Energy Demand Management and smart meters that offer variable market pricing over the course of the day. For example, municipal water pumps that feed a water tower do not need to operate continuously and can be restricted to times when electricity is plentiful and cheap. Consumers could choose when to run the dishwasher or charge an electric vehicle (PHEV or EV), making it very convenient. PHEV/EV's are likely to be a very important source of demand management, which would mostly charge at night when wind power is most likely to be surplus, and whose charging could be scheduled in an automated fashion for periods of greatest wind output.
Turbine placement
As a general rule, wind generators are practical where the average wind speed is 10 mph (16 km/h or 4.5 m/s) or greater. Usually sites are pre-selected on basis of a wind atlas, and validated with wind measurements. Obviously, meteorology plays an important part in determining possible locations for wind parks, though it has great accuracy limitations. Meteorological wind data is not usually sufficient for accurate siting of a large wind power project. Site Specific Meteorological Data is crucial to determining site potential. An 'ideal' location would have a near constant flow of non-turbulent wind throughout the year and would not suffer too many sudden powerful bursts of wind. An important turbine siting factor is access to local demand or electric power transmission capacity.
The most crucial step in the development of a potential wind site is the collection of accurate and verifiable wind speed and direction data as well as other site parameters. Meteorological Tower Installation To collect wind data a Meteorological Tower is installed at the potential site with instrumentation installed at various heights along the tower. All towers include anemometers to determine the wind speed and wind vanes to determine the direction. The towers generally vary in height from 30 to 60 meters. The towers primarily used in determining site feasibility for potential wind farms are guyed steel-pipe structures which are left to collect data for one to two years and then usually disassembled. Data is collected by a data logging device which stores and transmits data to a server where it is analyzed.
The wind blows faster at higher altitudes because of the reduced influence of drag of the surface (sea or land) and the reduced viscosity of the air. The increase in velocity with altitude is most dramatic near the surface and is affected by topography, surface roughness, and upwind obstacles such as trees or buildings. Typically, the increase of wind speeds with increasing height follows a logarithmic profile that can be reasonably approximated by the wind profile power law, using an exponent of 1/7th, which predicts that wind speed rises proportionally to the seventh root of altitude. Doubling the altitude of a turbine, then, increases the expected wind speeds by 10% and the expected power by 34% (calculation: increase in power = (2.0) ^(3/7) – 1 = 34%).
Wind farms or wind parks often have many turbines installed. Since each turbine extracts some of the energy of the wind, it is important to provide adequate spacing between turbines to avoid excess energy loss. Where land area is sufficient, turbines are spaced three to five rotor diameters apart perpendicular to the prevailing wind, and five to ten rotor diameters apart in the direction of the prevailing wind, to minimize efficiency loss. The "wind park effect" loss can be as low as 2% of the combined nameplate rating of the turbines.
Utility-scale wind turbine generators have minimum temperature operating limits which restrict the application in areas that routinely experience temperatures less than −20 °C. Wind turbines must be protected from ice accumulation, which can make anemometer readings inaccurate and which can cause high structure loads and damage. Some turbine manufacturers offer low-temperature packages at a few percent extra cost, which include internal heaters, different lubricants, and different alloys for structural elements, to make it possible to operate the turbines at lower temperatures. If the low-temperature interval is combined with a low-wind condition, the wind turbine will require station service power, equivalent to a few percent of its output rating, to maintain internal temperatures during the cold snap. For example, the St. Leon, Manitoba, Manitoba project has a total rating of 99 MW and is estimated to need up to 3 MW (around 3% of capacity) of station service power a few days a year for temperatures down to −30 °C. This factor affects the economics of wind turbine operation in cold climates.
Onshore
Onshore turbine installations in hilly or mountainous regions tend to be on ridgelines generally three kilometers or more inland from the nearest shoreline. This is done to exploit the so-called topographic acceleration. The hill or ridge causes the wind to accelerate as it is forced over it. The additional wind speeds gained in this way make large differences to the amount of energy that is produced. Great attention must be paid to the exact positions of the turbines (a process known as micro-siting) because a difference of 30m can sometimes mean a doubling in output. Local winds are often monitored for a year or more with anemometers and detailed wind maps constructed before wind generators are installed.
For smaller installations where such data collection is too expensive or time consuming, the normal way of prospecting for wind-power sites is to directly look for trees or vegetation that are permanently "cast" or deformed by the prevailing winds. Another way is to use a wind-speed survey map, or historical data from a nearby meteorological station, although these methods are less reliable.
Wind farm siting can sometimes be highly controversial, particularly as the hilltop, often coastal sites preferred are often picturesque and environmentally sensitive (for instance, having substantial bird life). Local residents in a number of potential sites have strongly opposed the installation of wind farms, and political support has resulted in the blocking of construction of some installations.{{cite news|date = [2006-04-05 |accessdate = 2006-08-18 -->
Near-Shore
Near-Shore turbine installations are generally considered to be inside a zone that is on land within three kilometers of a shoreline or on water within ten kilometers of land. These areas tend to be windy and are good sites for turbine installation, because a primary source of wind is convection caused by the differential heating and cooling of land and sea over the cycle of day and night. Wind speeds in these zones share the characteristics of both onshore and offshore wind, depending on the prevailing wind direction.
Common issues that are shared within near-shore wind development zones are aviary (including bird migration and nesting), aquatic habitat, transportation (including shipping and boating) and visual aesthetics. Local residents in some potential sites have strongly opposed the installation of wind farms due to these concerns.
Offshore
Offshore wind development zones are generally considered to be ten kilometers or more from land. Offshore wind turbines are less obtrusive than turbines on land, as their apparent size and noise can be mitigated by distance. Because water has less surface roughness than land (especially deeper water), the average wind speed is usually considerably higher over open water. Capacity factors (utilisation rates) are considerably higher than for onshore and near-shore locations which allows offshore turbines to use shorter towers, making them less visible.
In stormy areas with extended shallow continental shelves (such as Denmark), turbines are practical to install — Denmark's wind generation provides about 18% of total electricity production in the country, with many offshore windfarms. Denmark plans to increase wind energy's contribution to as much as half of its electrical supply.
Locations have begun to be developed in the Great Lakes - with one project by Trillium Power approximately 20 km from shore and over 700 MW in size. Ontario, Canada is aggressively pursuing wind power development and has many onshore wind farms and several proposed near-shore locations but presently only one offshore development.
In most cases offshore environment is more expensive than onshore. Offshore towers are generally taller than onshore towers once the submerged height is included, and offshore foundations are more difficult to build and more expensive. Power transmission from offshore turbines is generally through submarine cable, which is more expensive to install than cables on land, and may use high voltage direct current operation if significant distance is to be covered — which then requires yet more equipment. Offshore saltwater environments can also raise maintenance costs by corroding the towers, but fresh-water locations such as the Great Lakes do not. Repairs and maintenance are usually much more difficult, and generally more costly, than on onshore turbines. Offshore saltwater wind turbines are outfitted with extensive corrosion protection measures like coatings and cathodic protection, which may not be required in fresh water locations.
While there is a significant market for small land-based windmills, offshore wind turbines have recently been and will probably continue to be the largest wind turbines in operation, because larger turbines allow for the spread of the high fixed costs involved in offshore operation over a greater quantity of generation, reducing the average cost. For similar reasons, offshore wind farms tend to be quite large—often involving over 100 turbines—as opposed to onshore wind farms which can operate competitively even with much smaller installations.
Airborne
Wind turbines might also be flown in high speed winds at altitude, although no such systems currently exist in the marketplace. An Ontario (Canada) company, Magenn Power, Inc., is attempting to commercialize tethered aerial turbines suspended with helium
The Italian project called "Kitegen" uses a prototype vertical-axis wind turbine. It is an innovative plan (still in the construction phase) that consists of one wind farm with a vertical spin axis, and employs kites to exploit high-altitude winds. The Kite Wind Generator (KWG) or KiteGen is claimed to eliminate all the static and dynamic problems that prevent the increase of the power (in terms of dimensions) obtainable from the traditional horizontal-axis wind turbine generators.A number of other designs for vertical-axis turbines have been developed or proposed, including small scale commercial or pilot installations. However, vertical-axis turbines remain a commercially unproven technology.
Utilization
Large scale
{| class="wikitable" style="float: right; margin-left: 10px"! colspan="5" align=center style="background-color: #cfb;" | Installed windpower capacity (MW)|-! style="background-color: #cfb;" | Rank! style="background-color: #cfb;" | Nation! style="background-color: #cfb;" align=right | 2005! style="background-color: #cfb;" align=right | 2006! style="background-color: #cfb;" align=right | Latest|-| align=right | 1 || Wind power in Germany || align=right | 18,415 || align=right | 20,622 || align=right | 21,283|-| align=right | 2 || Wind power in Spain || align=right | 10,028 || align=right | 11,615 || align=right | 12,801|-| align=right | 3 || Wind power in the United States || align=right | 9,149 || align=right | 11,603 || align=right | 12,634|-| align=right | 4 || Wind power in India || align=right | 4,430 || align=right | 6,270 || align=right | 7,231|-| align=right | 5 || Wind power in Denmark || align=right | 3,136 || align=right | 3,140 || align=right ||-| align=right | 6 || China || align=right | 1,260 || align=right | 2,604 || align=right | 2,956|-| align=right | 7 || Italy || align=right | 1,718 || align=right | 2,123 || align=right ||-| align=right | 8 || Wind power in the United Kingdom || align=right | 1,332 || align=right | 1,963 || align=right | 2,191|-| align=right | 9 || Renewable energy in Portugal || align=right | 1,022 || align=right | 1,716 || align=right | 1,874|-| align=right | 10 || List of wind farms in Canada || align=right | 683 || align=right | 1,459 || align=right | 1,670|-| align=right | 11 || France || align=right | 757 || align=right | 1,567 || align=right ||-| align=right | 12 || Netherlands || align=right | 1,219 || align=right | 1,560 || align=right ||-| align=right | 13 || Japan || align=right | 1,061 || align=right | 1,394 || align=right ||-| align=right | 14 || Austria || align=right | 819 || align=right | 965 || align=right ||-| align=right | 15 || Wind power in Australia || align=right | 708 || align=right | 817 || align=right ||-| align=right | 16 || Greece || align=right | 573 || align=right | 746 || align=right | 795|-| align=right | 17 || Ireland || align=right | 496 || align=right | 745 || align=right | 866|-| align=right | 18 || Sweden || align=right | 510 || align=right | 572 || align=right ||-| align=right | 19 || Norway || align=right | 267 || align=right | 314 || align=right ||-| align=right | 20 || Brazil || align=right | 29 || align=right | 237 || align=right ||-| align=right | 21 || Egypt || align=right | 145 || align=right | 230 || align=right | 580|-| align=right | 22 || Belgium || align=right | 167 || align=right | 193 || align=right ||-| align=right | 23 || Taiwan || align=right | 104 || align=right | 188 || align=right ||-| align=right | 24 || South Korea || align=right | 98 || align=right | 173 || align=right ||-| align=right | 25 || New Zealand || align=right | 169 || align=right | 171 || align=right | 322|-| align=right | 26 || Poland || align=right | 83 || align=right | 153 || align=right | 216|-| align=right | 27 || Morocco || align=right | 64 || align=right | 124 || align=right ||-| align=right | 28 || Mexico || align=right | 3 || align=right | 88 || align=right ||-| align=right | 29 || Finland || align=right | 82 || align=right | 86 || align=right | 107|-| align=right | 30 || Ukraine || align=right | 77 || align=right | 86 || align=right ||-| align=right | 31 || Costa Rica || align=right | 71 || align=right | 74 || align=right ||-| align=right | 32 || Hungary ] || align=right | 23 || align=right | 48 || align=right ||-| align=right | || Rest of Europe || align=right | 129 || align=right | 163 || align=right ||-| align=right | || Rest of Americas || align=right | 109 || align=right | 109 || align=right ||-| align=right | || Rest of Asia || align=right | 38 || align=right | 38 || align=right ||-| align=right | || Rest of Africa & Middle East || align=right | 31 || align=right | 31 || align=right ||-| align=right | || Rest of Oceania || align=right | 12 || align=right | 12 || align=right ||-|! style="background-color: #cfb;" | World total (MW)| align=right style="background-color: #cfb;" | 59,091 || align=right style="background-color: #cfb;" | 74,223 || align=right style="background-color: #cfb;" | 79,341|}
There are many thousands of wind turbines operating, with a total capacity of 73,904 MW of which Europe accounts for 65% (2006). The average output of one megawatt of wind power is equivalent to the average electricity consumption of about 250 American households. Wind power was the most rapidly-growing means of alternative electricity generation at the turn of the century and world wind generation capacity more than quadrupled between 2000 and 2006. 81% of wind power installations are in the US and Europe, but the share of the top five countries in terms of new installations fell from 71% in 2004 to 55% in 2005.
By 2010, the World Wind Energy Association expects 160GW of capacity to be installed worldwide, up from 73.9GW at the end of 2006, implying an anticipated net growth rate of more than 21% per year.
Germany, Spain, the United States, India, and Denmark have made the largest investments in wind generated electricity. Denmark is prominent in the manufacturing and use of wind turbines, with a commitment made in the 1970s to eventually produce half of the country's power by wind. Denmark generates over 20% of its electricity with wind turbines, the highest percentage of any country and is fifth in the world in total power generation (which can be compared with the fact that Denmark is 56th on the List of countries by electricity consumption). Denmark and Germany are leading exporters of large (0.66 to 5 MW) turbines.
Wind accounts for 1% of the total electricity production on a global scale (2005). Germany is the leading producer of wind power with 28% of the total world capacity in 2006 (7.3% of German electricity); the official target is that by 2010, renewable energy will meet 12.5% of German electricity needs — it can be expected that this target will be reached even earlier. Germany has 18,600 wind turbines, mostly in the north of the country — including three of the biggest in the world, constructed by the companies Enercon (6 MW), Multibrid (5 MW) and Repower (5 MW). Germany's Schleswig-Holstein province generates 36% of its power with wind turbines.
Spain and the United States are next in terms of installed capacity. In 2005, the government of Spain approved a new national goal for installed wind power capacity of 20,000 MW by 2012. According to trade journal Windpower Monthly; however, in 2006 they abruptly halted subsidies and price supports for wind power. According to the American Wind Energy Association, wind generated enough electricity to power 0.4% (1.6 million households) of total electricity in US, up from less than 0.1% in 1999. In 2005, both Germany and Spain have produced more electricity from wind power than from hydropower plants. US Department of Energy studies have concluded wind harvested in just three of the fifty U.S. states could provide enough electricity to power the entire nation, and that offshore wind farms could do the same job.
In recent years, the United States has added more wind energy to its grid than any other single country, and capacity is expected to grow by 3 gigawatts (3,000 megawatts) in 2007. Texas has become the leader in Wind Energy production, far surpassing California. In 2007, the state expects to add 2 gigawatts to raise its existing capacity to approximately 4.5 gigawatts. Iowa and Minnesota are expected to reach the 1 gigawatt mark by the end of 2007. http://awea.org/projects Wind power generation in the U.S. was up 31.8% in February, 2007 from February, 2006.http://www.eia.doe.gov/cneaf/electricity/epm/epm_sum.html
India ranks 4th in the world with a total wind power capacity of 6,270 MW in 2006. Wind power generates 3% of all electricity produced in India. The World Wind Energy Conference in New Delhi in November 2006 has given additional impetus to the Indian wind industry. The windfarm near Muppandal, India, provides an impoverished village with energy for work.{{cite web] is one of the world's largest wind turbine manufacturers. Suzlon Energy
In December 2003, General Electric installed the world's largest offshore wind turbines in Ireland, and plans are being made for more such installations on the west coast, including the possible use of floating turbines.
On August 15, 2005, People's Republic of China announced it would build a 1000-megawatt wind farm in Hebei for completion in 2020. China reportedly has set a generating target of 20,000 MW by 2020 from renewable energy sources — it says indigenous wind power could generate up to 253,000 MW. Following the World Wind Energy Conference in November 2004, organised by the Chinese and the World Wind Energy Association, a Chinese renewable energy law was adopted. In late 2005, the Chinese government increased the official wind energy target for the year 2020 from 20 GW to 30 GW.Lema, Adrian and Kristian Ruby, ”Between fragmented authoritarianism and policy coordination: Creating a Chinese market for wind energy”, Energy Policy, Vol. 35, Isue 7, July 2007
Mexico recently opened La Venta II wind power project as an important step in reducing Mexico's consumption of fossil fuels. The project (88MW) the first of its kind in Mexico, will provide 13 percent of the electricity needs of the state of Oaxaca and by 2012 will have a capacity of 3500 MW.
Another growing market is Brazil, with a wind potential of 143 GW. The federal government has created an incentive program, called Proinfa, to build production capacity of 3300 MW of renewable energy for 2008, of which 1422 MW through wind energy. The program seeks to produce 10% of Brazilian electricity through renewable sources. Brazil produced 320 TWh in 2004. France recently announced a very ambitious target of 12 500 MW installed by 2010., Tamilnadu in India
Over the 7 years from 2000-2006, Canada experienced rapid growth of wind capacity — moving from a total installed capacity of 137 MW to 1,451 MW, and showing a growth rate of 38% and rising. Particularly rapid growth has been seen in 2006, with total capacity growing to 1,451 MW by December, 2006, doubling the installed capacity from the 684 MW at end-2005. This growth was fed by provincial measures, including installation targets, economic incentives and political support. For example, the government of the Canadian province of Ontario announced on 21 March 2006 that it will introduce a feed-in tariff for wind power, referred to as 'Standard Offer Contracts', which may boost the wind industry across the province. In the Canadian province of Quebec, the state-owned hydroelectric utility plans beside current wind farm projects to purchase an additional 2000 MW by 2013.
Wind power in Europe
{| class="wikitable" style="foat right" margin-left: 10px"! colspan="5" align=center style="background-color: #cfb;" | Wind Power in Europe 2006 (MW)|-! style="background-color: #cfb;" | No! align=left style="background-color: #cfb;" | Country! align=right style="background-color: #cfb;" | Addition! align=right style="background-color: #cfb;" | Total
|-| align=right | 1 || Wind power in Germany || align=right | 2 233 || align=right | Renewable energy in Germany|-| align=right | 2 || Wind power in Spain || align=right | 1 587 || align=right | 11 615|-| align=right | 3 || Wind power in France || align=right | 810 || align=right | 1 567|-| align=right | 4 || Wind power in Portugal || align=right | 694 || align=right | 1 716|-| align=right | 5 || Wind power in the United Kingdom || align=right | 634 || align=right | 1 963|-| align=right | 6 || Italy || align=right | 417 || align=right | 2 123|-| align=right | 7 || Netherlands || align=right | 356 || align=right | 1 560|-| align=right | 8 || Ireland || align=right | 250 || align=right | 745|-| align=right | 9 || Greece || align=right | 173 || align=right | 746|-| align=right | 10 || Austria || align=right | 146 || align=right | 965|-| align=right | 11 || Poland || align=right | 69 || align=right | 152|-| align=right | 12 || Sweden || align=right | 62 || align=right | 572|-| align=right | 13 || Lithuania || align=right | 49 || align=right | 55|-| align=right | 14 || Hungary || align=right | 43 || align=right | 61|-| align=right | 15 || Belgium || align=right | 26 || align=right | 193|-| align=right | 16 || Czech Republic || align=right | 22 || align=right | 50|-| align=right | 17 || Bulgaria || align=right | 22 || align=right | 32|-| align=right | 18 || Wind power in Denmark || align=right | 11 || align=right | 3 140|-| align=right | 19 || Finland || align=right | 4 || align=right | 86|-| align=right | 20 || Romania || align=right | 1 || align=right | 3|-| align=right | 21 || Luxembourg || align=right | 0 || align=right | 35|-| align=right | 22 || Estonia || align=right | 0 || align=right | 32|-| align=right | 23 || Latvia || align=right | 0 || align=right | 27|-| align=right | 24 || Slovenia || align=right | 0 || align=right | 5|-| align=right | 25 || Slovakia || align=right | 0 || align=right | 0|-| align=right | 26 || Cyprus || align=right | 0 || align=right | 0|-| align=right | 27 || Malta || align=right | 0 || align=right | 0|-! colspan="2" align=left style="background-color: #cfb;" | EU27 (MW)| align=right style="background-color: #cfb;" | 7 609 || align=right style="background-color: #cfb;" | 48 061|-| align=right | 28 || Norway || align=right | 47 || align=right | 314|-! colspan="2" align=left style="background-color: #cfb;" | Europe (MW)| align=right style="background-color: #cfb;" | 7 708 || align=right style="background-color: #cfb;" | 48 545|-----| colspan=9 align=left | ref in discussion|}
Small scale
and runs various 12 volt appliances within the building on which it is installed.
Small Wind is defined as wind generation systems with capacities of 100 kW or less and are usually used to power homes, farms, and small businesses. Individuals purchase these systems to reduce or eliminate their electricity bills, to avoid the unpredictability of natural gas prices, or simply to generate their own clean power.
Wind turbines have been used for household electricity generation in conjunction with Battery (electricity) storage over many decades in remote areas, but increasingly, U.S. consumers are choosing to purchase grid-connected turbines in the 1 to 10 kilowatt range to power their whole homes. Household generator units of more than 1 kW are now functioning in several countries, and in every state in the U.S.
To compensate for the varying power output, grid-connected wind turbines may utilise some sort of grid energy storage. Off-grid systems either adapt to intermittent power or use photovoltaic or diesel systems to supplement the wind turbine.
Wind turbines range from small four hundred watt generators for residential use to several megawatt machines for wind farms and offshore. The small ones sometimes, but not always, have direct drive generators, direct current output, aeroelastic blades, lifetime bearings and use a vane to point into the wind; while the larger ones generally have geared power trains, alternating current output, flaps and are actively pointed into the wind. Direct drive generators and aeroelastic blades for large wind turbines are being researched and direct current generators are sometimes used.
In urban locations, where it is difficult to obtain predictable or large amounts of wind energy, smaller systems may still be used to run low power equipment. Distributed generation from rooftop mounted wind turbines can also alleviate power distribution problems, as well as provide resilience to power failures. Equipment such as parking meters or wireless internet gateways may be powered by a wind turbine that charges a small battery, replacing the need for a connection to the power grid and/or maintaining service despite possible power grid failures.
While installing a small wind turbine on a roof (rather than a tall tower elsewhere on a property) can be done successfully, there are a few inherent issues that this type of installation faces: Whether the roof can support the turbine's weight, how the building tolerates the vibrations from the spinning rotor, and the turbulence caused by the roof ledge and the resulting unpredictability in wind patterns.
Small scale turbines for residential-scale use are available that are approximately 7 feet (2 m) to in diameter and produce electricity at a rate of 900 watts to 10,000 watts at their tested wind speed. Some units are designed to be very lightweight, e.g. 16 kilograms (35 lb), allowing rapid response to wind gusts typical of urban settings and easy mounting much like a television antenna. It is claimed that they are inaudible even a few feet under the turbine. Dynamic braking regulates the speed by dumping excess energy, so that the turbine continues to produce electricity even in high winds. The dynamic braking resistor may be installed inside the building to provide heat (during high winds when more heat is lost by the building, while more heat is also produced by the braking resistor). The proximal location makes low voltage (12 volt, or the like) energy distribution practical. An additional benefit is that owners become more aware of electricity consumption, possibly reducing their consumption down to the average level that the turbine can produce.
The American Wind Energy Association has released several studies on the small wind turbine market in the U.S. and abroad, showing that the U.S. continues to dominate the Small Wind industry. According to another organization, the World Wind Energy Association, it is difficult to assess the total number or capacity of small-scaled wind turbines, but in China alone, there are roughly 300,000 small-scale wind turbines generating electricity.
The dominant model on the market, especially in the United States, is the propeller-shaped "Horizontal Axis" type, which resembles the large, utility-scale turbines used in wind "farms." An alternative model is known as "Vertical Axis," and rotates like a top and can come in many different designs.
There have been a number of recent developments of mini-windmills which could be adapted to home use, including:
- The AeroTecture Wind turbine#Vertical axis AeroTecture
- The AeroVironment Architectural Wind Project 'Micro' wind turbines are coming to town, CNET, February 10, 2006, Martin LaMonica
- The piezoelectric windmill project
- The Swift home wind turbine. Swift Turbines The Swift project peaked in 2004 and has had some implementation difficulties while promising to be a low-noise/safe roof-mount/low-cost alternative Better Generation: Swift Rooftop wind energy system discussion
- The Motorwave micro-wind turbine Motorwind Lucien Gambarota: Alternative energy pioneer, CNN, 16 April 2007 Motorwind Turbines
Consumer guides are available to help potential customers learn about residential-scale wind systems, three of which are:
- "Small Wind Electric Systems: A U.S. Consumer's Guide" by the Dept. of Energy's Wind Powering America program
- "Wind Turbine Buyer's Guide" From Home Power Magazine
- "Apples & Oranges 2002: Choosing a Home-Sized Wind Generator"
Much more information is also available at the American Wind Energy Association's web site at:
- www.awea.org/smallwind
- FAQ: http://www.awea.org/smallwind/faq.html
- www.awea.org/smallwind/toolbox2/index.html
Wind power: key issues
Wind power can be a controversial issue, and several main areas of dispute are debated between supporters and opponents.
E70-4 in Germany
Growth and cost trends
Global Wind Energy Council (GWEC) figures show that 2006 recorded an increase of installed capacity of 15,197 megawatts (MW), taking the total installed wind energy capacity to 74,223 MW, up from 59,091 MW in 2005. Despite constraints facing supply chains for wind turbines, the annual market for wind continued to increase at an estimated rate of 32% following the 2005 record year, in which the market grew by 41%. 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 2006 reaching €18 billion, or US$23 billion.
The countries with the highest total installed capacity are Wind power in Germany (20,621 MW), Wind power in Spain (11,615 MW), the USA (11,603 MW), India (6,270 MW) and Wind power in Denmark (3,136). Thirteen countries around the world can now be counted among those with over 1,000 MW of wind capacity. In terms of new installed capacity in 2006, the US leads with 2,454 MW, followed by Germany (2,233 MW), India (1,840 MW), Spain (1,587 MW), China (1,347 MW) and France (810 MW).
In 2004, wind energy cost one-fifth of what it did in the 1980s, and some expected that downward trend to continue as larger multi-megawatt Wind turbine are mass-produced. However, installation costs have increased significantly in 2005 and 2006, and according to the major U.S. wind industry trade group, now average over US$1,600 per kilowatt, compared to $1200/kW just a few years before. A British Wind Energy Association report gives an average generation cost of onshore wind power of around 3.2 pence per kilowatt hour (2005). BWEA report on onshore wind costs Cost per unit of energy produced was estimated in 2006 to be comparable to the cost of new generating capacity in the United States for coal and natural gas: wind cost was estimated at $55.80 per MWh, coal at $53.10/MWh and natural gas at $52.50.http://www.eia.doe.gov/oiaf/ieo/pdf/0484(2006).pdf Energy Information Administration, "International Energy Outlook", 2006, p. 66. Other sources in various studies have estimated wind to be more expensive than other sources (see Economics of new nuclear power plants, Clean coal, and Carbon capture and storage).
Most major forms of electricity generation are capital intensive, meaning that they require substantial investments at project inception, and low ongoing costs (generally for fuel and maintenance). This is particularly true for wind and hydro power, which have fuel costs close to zero and relatively low maintenance costs; in economic terms, wind power has an extremely low marginal cost and a high proportion of up-front capital costs. The estimated "cost" of wind energy per unit of production is generally based on average cost per unit, which incorporates the cost of construction, borrowed funds, return to investors (including cost of risk), estimated annual production, and other components. Since these costs are averaged over the projected useful life of the equipment, which may be in excess of twenty years, cost estimates per unit of generation are highly dependent on these assumptions. Figures for cost of wind energy per unit of production cited in various studies can therefore differ substantially. The cost of wind power also depends on several other factors, such as installation of power lines from the wind farm to the national grid and the frequency of wind at the site in question.
Estimates for cost of production use similar methodologies for other sources of electricity generation. Existing generation capacity represents sunk costs, and the decision to continue production will depend on marginal costs going forward, not estimated average costs at project inception. For example, the estimated cost of new wind power capacity may be lower than that for "new coal" (estimated average costs for new generation capacity) but higher than for "old coal" (marginal cost of production for existing capacity). Therefore, the choice to increase wind capacity by building new facilities will depend on more complex factors than cost estimates, including the profile of existing generation capacity.
Research from a wide variety of sources in various countries shows that support for wind power is consistently between 70 and 80 per cent amongst the general public. Fact sheet 4: Tourism
Scalability
A key issue debated about wind power is its ability to scale to meet a substantial portion of the world's energy demand. There are significant economic, technical, and ecological issues about the large-scale use of wind power that may limit its ability to replace other forms of energy production. See, for example, the annual report of the Independent Electricity System Operator in Ontario, Canada . Most forms of electricity production also involve such trade-offs, and many are also not capable of replacing all other types of production for various reasons. A key issue in the application of wind energy to replace substantial amounts of other electrical production is Intermittent Power Sources; see the section below on Economics and Feasibility. At present, it is unclear whether wind energy will eventually be sufficient to replace other forms of electricity production, but this does not mean wind energy cannot be a significant source of clean electrical production on a scale comparable to or greater than other technologies, such as hydropower. Most electrical grids use a mix of different generation types (baseload generating capacity and peaking capacity) to match demand cycles by attempting to match the variable nature of demand to the most economic form of production; with the exception of hydropower, most types of production capacity are not used for all production (hydropower usage is limited by the presence of appropriate geographical sites). For example, nuclear power is effective as a baseload technology, but cannot be easily varied in short timeframes, and gas turbine plants are most economically used as peaking capacity; coal generation is primarily considered appropriate for baseload generation with some capacity to cycle to meet demand.
A significant part of the debate about the potential for wind energy to substitute for other electric production sources is the level of penetration. With the exception of Denmark, no countries or electrical systems produce more than 10% from wind energy, and most are below 2% (of course, this is in large part because wind power is a relatively new technology, with the vast majority of installations having taken place within the last 10 years). While the feasibility of integrating much higher levels (beyond 25%) is debated, significantly more wind energy could be produced worldwide before these issues become significant. In Denmark, wind power now accounts for close to 20% of electricity productionhttp://www.windpower.org/en/stats/shareofconsumption.htm and a recent poll of Danes show that 90% want more wind power installed.http://www.windpower.org/composite-1172.htm
Theoretical potential
Wind's long-term theoretical potential is much greater than current world energy consumption. The most comprehensive study to date found the potential of wind power on land and near-shore to be 72 Watt (~171,000 Ton of oil equivalent), or over fifteen times the world's current energy use and 40 times the current electricity use. The potential takes into account only locations with Class 3 (mean annual wind speeds ≥ 6.9 m/s at 80 m) or better wind regimes, which includes the locations suitable for low-cost (0.03–0.04 $/kWh) wind power generation and is in that sense conservative. It assumes 6 turbines per square km for 77 m diameter, 1.5 MW-turbines on roughly 13% of the total global land area (though that land would also be available for other compatible uses such as farming). However, the authors are quick to point out that many practical barriers would need to be overcome to reach this theoretical capacity. The calculations of potential assumes a capacity factor of 48% and does not take into account the practicality of reaching the windy sites, of transmission (including 'choke' points), of competing land uses, of transporting power over large distances, or of switching to wind power.
To determine the more realistic technical potential, it is essential to estimate how large a fraction of this land could be made available to wind power. In the 2001 IPCC report, it is assumed that a use of 4% – 10% of that land area would be practical.
Although the theoretical potential is vast, the amount of production that could be economically viable depends on a number of exogenous and endogenous factors, including the cost of other sources of electricity and the future cost of wind energy farms.
Offshore resources experience mean wind speeds about 90% greater than those on land, so offshore resources could contribute about seven times more energy than land. This number could also increase with higher altitude or airborne wind turbines.
Economics and feasibility
, in California. Developed during a period of tax incentives in the 1980s, this wind farm has more turbines than any other in the United States, producing about 125 MW. Wind Plants of California's Altamont Pass Considered largely obsolete, these turbines produce only a few tens of kilowatts each.
Wind energy in many jurisdictions receives some financial or other support to encourage its development. A key issue is the comparison to other forms of energy production, and their total cost. Two main points of discussion arise: direct subsidy and externalities for various sources of electricity, including wind. Wind energy benefits from subsidies of various kinds in many jurisdictions, either to increase its attractiveness, or to compensate for subsidies received by other forms of production or which have significant negative externalities. Without the handsome tax incentives (also know as subsidies) in fact, almost no wind power installation is economically feasible at present.
Most forms of energy production create some form of negative externality: costs that are not paid by the producer or consumer of the good. For electric production, the most significant externality is pollution, which imposes costs on society in the form of increased health expenses, reduced agricultural productivity, and other problems. In addition, carbon dioxide, a greenhouse gas produced when fossil fuels are burned for electricity production, may impose even greater costs on society in the form of global warming. Few mechanisms currently exist to impose (or internalise) these external costs in a consistent way between various industries or technologies, and the total cost is highly uncertain. Other significant externalities can include national security expenditures to ensure access to fossil fuels, remediation of polluted sites, destruction of wild habitat, loss of scenery/tourism, etc.
Wind energy supporters argue that, once external costs and subsidies to other forms of electrical production are accounted for, wind energy is amongst the most cost-effective forms of electrical production. Critics argue that the level of required subsidies, the small amount of energy needs met, and the uncertain financial returns to wind projects — that is, the all-in cost of wind energy compared to other technologies - make it inferior to other energy sources. Intermittency and other characteristics of wind energy also have costs that may rise with higher levels of penetration, and may change the cost-benefit ratio.
- Conventional and nuclear power plants receive substantial direct and indirect governmental subsidies. If a comparison is made on total production costs (including subsidies), wind energy may or may not be competitive compared to other energy sources. If the full costs (environmental, health, etc.) are taken into account, wind energy may be competitive in more cases. Wind energy costs have generally decreased due to technology development and scale enlargement. However, the cost of other capital intensive generation technologies, such as nuclear and fossil fueled plants, is also subject to cost reductions due to economy of scale and technological improvements.
- Nuclear power plants generally receive special Price-Anderson Nuclear Industries Indemnity Act from the disasters they may cause, which prevents victims from recovering the cost of their continued health care from those responsible, even in the case of criminal malfeasance. In many cases, nuclear plants are owned directly by governments or substantially supported by them. In both cases, nuclear plants benefit from a lower cost of capital and lower perceived risk, as governments take on the risk charge directly. This is a form of indirect subsidy, although the size of this subsidy is difficult to ascertain precisely.
- To compete with traditional sources of energy, wind power often receives financial incentives. In the United States, wind power receives a tax credit for each kilowatt-hour produced; at 1.9 cents per kilowatt-hour 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 Wind Power Production Incentive 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.
- Many potential sites for wind farms are far from demand centers, requiri
BBC - Weather Centre - Climate Change - Wind Power
BBC Weather's climate change site. All the issues and key topics including global warming, greenhouse effect, ozone, kyoto, politics and the environment.
Wind Power in the UK...
How serious is climate change? Why do we need wind farms? How economic are wind farms? Are wind farms a risk to birds? Are wind farms noisy? What do wind farm neighbours really ...
Devon Wind Power
Devon Wind Power with the aim of providing information on the Fullabrook Down wind farm proposal specifically and wind energy generation generally
Energy Resources: Wind power
Fireworks Splice HTML ... Introduction We've used the wind as an energy source for a long time.
CBBC Newsround | GLOBAL WARMING | Wind power
Find out about global warming ... Wind power Wind can be used to drive turbines which in turn produce electricity UK already has over 1,000 wind turbines First built in Cornwall ...
Wind Power Experiments
Provides technical data and information for hobbyist. Includes windmill plans and experiments.
npower renewables
Loading redirection target. In approx. 2 seconds the redirection target page should load. If it doesn't please select the link above.
Wind Power
Impartial information and advice on saving money on your energy bills and how to be more energy efficient in the home by using wind powered solutions.
Crash Course in Wind Energy
Here you will get a quick overview of wind energy and wind resources. The page is useful for schools and education in wind energy. ... Welcome to a Crash Course in Wind Energy Here ...
WIND POWER
Your description here... ... March 06 - 10, 2006. Part 1 of this course covers all the basic requirements for choosing and installing a wind energy system, and is suitable for ...
