Wind power or wind energy is mostly the use of wind turbines to generate electricity. Wind power is a popular, sustainable, renewable energy source that has a much smaller impact on the environment than burning fossil fuels. Historically, wind power has been used in sails, windmills and windpumps but today it is mostly used to generate electricity. Wind farms consist of many individual wind turbines, which are connected to the electric power transmission network.
New onshore (on-land) wind farms are cheaper than new coal or gas plants, but expansion of wind power is being hindered by fossil fuel subsidies. Onshore wind farms have a greater visual impact on the landscape than some other power stations. Small onshore wind farms can feed some energy into the grid or provide power to isolated off-grid locations. Offshore wind farms provide a steadier and stronger source of energy and have less visual impact. Although there is less offshore wind power at present and construction and maintenance costs are higher, it is expanding.
Wind power is variable renewable energy, so power-management techniques are used to match supply and demand, such as: wind hybrid power systems, hydroelectric power or other dispatchable power sources, excess capacity, geographically distributed turbines, exporting and importing power to neighboring areas, or grid storage. As the proportion of wind power in a region increases the grid may need to be upgraded. Weather forecasting allows the electric-power network to be readied for the predictable variations in production that occur.
In 2021, wind supplied over 1800 TWh of electricity, which was over 6% of world electricity and about 2% of world energy. With about 100 GW added during 2021, mostly in China and the United States, global installed wind power capacity exceeded 800 GW.
When mechanical energy enhances a unit by harnessing wind power, it may be called a windmill, wind pump or wind charger. Wind energy can be used for anything from power on boats, battery charging or electricity to being used commercially. Examples of how wind energy can be used include:
Wind energy is often created on wind farms. Some wind farms are onshore, and the land is often used for additional purposes, such as allowing animals to graze. Some are offshore, which means they’re over water.
Wind turbines can function on their own or be connected to the power grid or solar cells. Wind turbines are designed with either a horizontal or a vertical axis.
It was centuries ago when the technology of wind energy made its first actual steps although simpler wind devices date back thousands of years ago with the vertical axis windmills found at the Persian-Afghan borders around 200 BC and the horizontal-axis windmills of the Netherlands and the Mediterranean following much later (1300-1875 AD). Further evolution and perfection of these systems. Was performed in the USA during the 19th century, i.e. when over 6 million of small machines were usedforwaterpumpingbetween1850and1970.Ontheotherhand, the first large wind machine to generate electricity (a low speed and high-solidity wind turbine (WT) of 12 kW) was installed in Cleveland, Ohio, in1888, while during the latest ages of World War I, use of 25 kW machines throughout Denmark was widespread. Further development of wind generators in the USA was inspired by the design of airplane propellers and monoplane wings, while subsequent efforts in Denmark, France, Germany, and the UK (during the period between 1935 and1970) showed that large-scale WTs could work. European developments continued after World War II. In Denmark, the Gedser mill 200 kW three-bladed upwind rotor WT operated successfully until the early 1960s, while in Germany, a series of advanced horizontal-axis designs were developed, with both of the aforementioned concepts dictating the future horizontal-axis design approaches later emerging in the 70s. One of the most important milestones of the wind energy history coincides with the USA government involvement in the wind energy research and development (R&D) after the oil crisis of 1973. Following, in the years between1973and1986, the commercial WT market evolved from domestic and agricultural (1-25 kW) to utility interconnected wind farm applications (50-600 kW). In this context, the first large-scale wind energy penetration outbreak was encountered in California, where over 16,000 machines, ranging from 20 to 350 kW (a total of 1.7 GW), were installed between 1981 and1990, as a result of the incentives (such as the federal investment and energy credits) given by the USA government. In northern Europe on the other hand, wind farm installations increased steadily through the 80s and the 90s, with the higher cost of electricity and the excellent wind resources leading to the creation of a small but stable market. After 1990 most market activity shifted to Europe, with the last twenty years bringing wind energy at the frontline of the global scene with major players from all world regions. In this context, in the current work, a short review of the developments noted in the field of wind energy at the global level is undertaken, with special emphasis given on the major fields of global market facts, technology issues, economics, environmental performance, wind energy prospects and R&D. Highlights and some insight for each of the fields are currently presented, while special attention is given to the European achievements. More specifically, in the global market facts’ section, the time evolution of the global wind power capacity and energy generation are presented along with the leading markets of today and the most important EU and world wind power facts. Following, in the technology issues section, discussion concerning the upscale of machines, the main technological characteristics of contemporary WTs and issues such as grid integration, efficiency of the machines and expansion of the small scale machines’ industry is undertaken. In the economics section, issues such as the time evolution of investment costs, the costs of both onshore and offshore applications, the effect of financial support mechanisms, the employment opportunities appearing due to the expansion of the wind energy industry as well as a comparison with other power generation technologies are all presented. Next, in the environmental performance section, a short notice on the impacts of wind energy is provided while attention is given to the externalities avoided and the social acceptance levels of wind power. Finally, in the wind energy prospects and R&D part, a summary of future targets is provided at both the market and the technological level.
According to the latest official data, the global wind power capacity was increased during 2009 by 37.4 GW, thus reaching a total of almost 158 GW on the basis of remarkable development rates exhibited for the past twenty years. Europe is at the moment approaching, if not yet exceeded, 80 GW and is now heading to offshore applications. In fact, it is since the mid-90s that the EU market corresponds to over 50% of the global installed capacity, that is nowadays said to yield an overall of 260TWh/year. In this context, although the EU held only 20% of the word wind energy generation in the early 90s, production of European wind parks managed to even reach 70% in the years after 2000, with a production of 100TWh/year already achieved by the end of 2007. However, restart of the USA market and development of the wind energy industry in China have considerably reduced the aforementioned numbers during the recent years to a current 60%. As a result, the aggregate share of North America and Asia & Oceania in 2007 corresponded to an approximate 38% of the world wind energy production. In the meantime, 80% of wind energy production attributed to North America in the early 90’s shrank to 20% within a decade’s time, while for the region of Asia & Oceania considerable contribution may be encountered since 1995. Concerning the present status of wind power capacity, the USA managed during 2009 to add a new 40% over its cumulative capacity. At the same time the Chinese achieved to install almost 14 GW, i.e. 20% and 40% of the EU and the USA cumulative capacity respectively, which leads to an aggregate (USA and China) of 62% of the 2009 capacity. As a result, China has reached the second place of the world ranking table together with the long term leader of the EU, i.e. Germany. Besides, at the regional level, Asia has managed to marginally exceed the North Americans in terms of cumulative capacity, while the EU is still the world leader with almost 50%. At the same time, at the European level Germany (25.8 GW) and Spain (19.1 GW) are now followed by Italy (4850MW), France (4492 MW), UK (4051 MW), Portugal (3535 MW) and Denmark (3465), with the latter presenting a long-term stagnation that calls for the improvement of the local legislation although considerable exploitation of the local wind potential has already been achieved. On the other hand, France and Portugal present remarkable developing rates since 2000, while for Italy and Netherlands the local wind energy market encountered an earlier start (i.e. since 1990) with analogous results only for the case of Italy. Further, what is also interesting to see is the time evolution of generating capacity of all technologies in the EU during the time from 1995 to 2009. during the last two years, new wind power capacity exceeds any other technology with more than 10 GW of wind power installed in 2009. Additionally, in terms of cumulative installations, European wind farms exceed oil-based generation by 20 GW and are down by 50 GW when compared to nuclear power. In fact, the developing rate of wind energy capacity is only comparable to the respective of natural gas installations, with the remarkable growth of photovoltaic plants also designating the shift attempted in the EU to clean power generation technologies. In this context, contribution shares of wind energy production to the gross electricity generation of certain EU countries already exceed 10% (e.g. Denmark, Portugal and Spain), while for the Danish approximately 20% should be considered, with the respective EU average kept at 4.1%. Nevertheless, shift to offshore attempted by many European countries (1.5 GW already in operation in Denmark and the UK), with short-term plans of 33 GW by 2015 mainly supported by Germany and UK, shall further increase the contribution shares of EU wind farms. Summarizing, according to the latest official data, the EU still remains the world leader, although the USA made a considerable come-back with over 10 GW installed in 2009. Meanwhile, China persists on its outstanding growth rates, each year doubling its cumulative capacity, and seems ready to overtake the first place in the world ranking table. On top of these, India following a steady growth rate is the China’s most important ally, adding more than10 GW for the Asian region. Besides, after a long stagnating period Australia managed to install almost 1 GW during 2008-09, thus increasing the Pacific capacity at more than 2GW. On the other hand, in the Latin America, noteworthy is only the development encountered in Brazil, Chile, Mexico and Costa Rica, summing up however to a total of only 1GW. Finally, Egypt, Morocco and Tunisia are the only active African countries (morethan0.7GW), with Iran being the only Middle East country found to considerably exploit its local wind potential (w100 MW).
The development of contemporary WTs in the course of time may be reflected by the gradual upscale of machines, based on the rationale for better land exploitation, presence of scale economies, reduced maintenance and operation (M&O) requirements and past funding development programs pushing towards the development of big-scale machines. On the other hand, a stabilizing trend is noted during the recent years that has put an end to the exponential increase of the rotor diameter met in the first two decades. As a result, WTs of nowadays are mainly in the order of 2-3MW, although larger scale machines that are already commercial do exist. Contrariwise, the shift to offshore applications calls for multi-MW solutions already offered by some of the manufacturers (even at the levels of 7 MW), while designs of machines that will exceed the nominal power of 10 MW are already underway. Meanwhile, during the evolution of technology, multi-bladed turbines are found to be constrained to water pumping applications. On the other hand, among the types of electricity generation, the three-bladed WTs prevailed over the respective single- and two-bladed machines that appeared to be both less efficient and less accepted concerning their visual impact. Similarly, the inherent lower efficiency and the cost-ineffectiveness were the main reasons for the vertical axis WTs (VAWTs) actually never becoming mainstream, although a new market seems to emerge for the smallest scale VAWTs in building applications. Concerning power regulation, pitch control found itself to be gradually more adaptable to new machines, with the ratio of pitch to stall machines increasing from 1:1 (1997) to 4:1 in 2006. Following, introduction of the variable speed concept, although inducing extra costs and additional losses in the variable speed drive, allowed for increased energy capture below the rated power area and relief of loads, enhancement of the pitch and smooth power output above the rated power area. In this context, a long term increase of the mean annual capacity factor(CF)met at both the EU and the global level, exceeding 20% in 2007, reflects the effect of technological improvements, this also including the gradual establishment of pitch control machines. More specifically, although good wind potential areas are now harder to find, exploitation of wind energy per kW has increased due to improved efficiency of contemporary turbines, sophisticated assessment of the local wind potential, considerable reduction of downtime periods, upgrade of networks and operation of offshore applications. In this context, of special interest are countries such as Germany and Denmark where although local wind potential keeps CFs at moderate values, diffusion of wind parks is remarkable, and countries such as Ireland, Spain and Turkey where the long-term CF is found to exceed 25%.
Another important technology issue is grid integration, with large-scale penetration of onshore and offshore wind parks challenging all parties involved and with system issues including power quality, voltage management, grid stability, grid adequacy, control of emissions and efficiency reduction of other generating plants. As a result, in order to confront future wind power grid integration, the main directions include design and operation of the power system with the introduction of demand side management techniques and energy storage, grid infrastructure issues meaning reinforcement and upgrade of networks, grid connection of wind power with grid codes issued, market operation with the introduction of more flexible mechanisms and other issues such as institutional. Finally, of special interest is as already implied, the industry of small scale WTs, satisfying a range of applications. Such applications may concern both on-grid and off-grid concepts like building integration, mini wind farms and single turbine installations for the first category, and wind-battery along with wind-based hybrid systems for the second. Besides, the interest lately exhibited may also be illustrated by the recent developments in the specific field, these including active pitch controls for high wind speeds, vibration isolators to dampen sound, advanced blade design, self-protection mechanisms for extreme winds, dual mode models (both on- and off-grid), software development, inverters fitted into the nacelle, attempts to make small WTs more aesthetically attractive and integration of small WTs into several structures.
Among the main trends dominating the market of wind energy during the years, one may note the size increase of contemporary WTs, the efficiency improvement and the long-term reduction of the specific investment cost per kW (turnkey cost) of installed wind power capacity. Concerning the latter, although starting from a remarkable 3500€/kW during the mid-eighties, it has during the last years stabilized in the order of 1200€/kW, i.e. between 1000 €/kW and 1400€/kW, depending also on the area of study. Italy UK Netherlands in this context, some rough numbers may also be given in terms of investment cost breakdown, noting also the difference between onshore and offshore applications. More specifically, the turbine component being critical in onshore projects (w930€/kW) drops to a typical 48% in offshore plants while on the other hand, foundation requirements increase by more than four times and grid connection in offshore is increased by more than 150€/kW. Overall, the total specific investment cost of offshore applications is found to be higher by more than 40% for most of the plants in operation and may increase to even exceed 3000€/kW for installations that are under construction. Besides, based on the experience of in operation offshore parks employment of more turbines implies relatively lower turnkey costs. Any case given, M&O costs including insurance, regular maintenance, repairs, spare parts, administration, land rent and others, are also considerable for wind power installations, although the introduction of more efficient machines and the reduction of downtime hours constantly decrease the M&O requirements which are now in the order of 1.2-1.5c€/kWh. On the other hand however, the wind energy production cost is found to be comparable with the respective of conventional fossil fueled generation methods, even without internalizing the externalities. As a result, clear advantage of wind power in the economic field as well becomes evident, with estimations concerning the near future electricity generation cost of onshore and offshore wind parks supporting values between 50€/MWh and 80€/MWh and between 75€/MWh and 120€/MWh respectively. Following, State support, as already seen in the introduction section, led to the outbreak of California. In this context, of analogous importance for the remarkable growth of the wind energy market has been the implementation of various support mechanisms including price- and quantity-driven instruments such as feed-in-tariffs, investment and production tax incentives for the first and quota along with tradable green certificates and tendering systems for the second. At this point, one should underline the effectiveness of most of these measures and especially the feed-in tariff mechanism, which since being adopted by the majority of leading countries worldwide (Germany, USA, China, Denmark, Spain, India, etc.) led to the remarkable growth of wind energy generation. Finally, one should also emphasize on the employment opportunities offered by the expansion of the wind energy market at a global level. Somewhat 100,000 plus 50,000 is the number of people employed directly and indirectly in the wind energy field of Europe, while another 85,000 correspond to the 100 manufacturing plants operating in the USA. These include employment posts in manufacturing companies, in promotion, utilities, engineering and R&D (direct employment) or employment in companies providing services or producing components for WTs (indirect relation). Note that according to rough estimations, among the leader countries on the basis of the people employed per MW installed ratio, Denmark, Belgium and Finland employ more than 7 persons while in terms of absolute numbers Germany currently employs 38,000 people.
Although suggesting an a-priori clean energy source, wind power also comes with certain environmental impacts such as the visual and the noise impact, the land use, the bird fatalities, the electromagnetic interference, the impacts on fish and marine mammals and the embodied energy plus LC emissions common in every power generation technology. Many of these impacts are nowadays perceived by many as “myths”, while others still lie on the subjectivity of oneself. What is documented however is that WTs require primary LC embodied energy amounts in the order of only 1e3MWh/kW (that usually implies energy payback periods of months), with the stage of manufacturing being the most demanding. Furthermore, if also considering externalities, a clear advantage may be recorded for wind power installations in comparison with conventional power plants. In fact, according to estimations, realization of the high expectations set by the EU for 2020 implies avoidance of externalities in the amount of almost 40 billion €/year, with the distribution of cost savings per country given in.
Besides that, environmental performance of wind energy perceived by the majority of people (over 70% in favor) and transformed in to widespread social support (only solar energy seems to be more socially accepted) further boosts wind energy developments. On the other hand, one of the challenges that wind energy is faced with during the recent years is the paradox of increased social support being obscured by real-life NIMBY attitudes, especially since availability of good sites is becoming increasingly rare.
Although wind energy is a renewable, greener option of energy, it still has its disadvantages and limitations.
1) Dangerous to Some Wildlife
Wind turbines are known to pose a threat to the wildlife. Flying birds and bats whose habitats or migratory paths could be injured or killed if they run into the blades that turn on the fanlike structure of wind turbines when they are spinning. The deaths of birds and bats are a controversial subject at wind farm sites, which has raised concerns by fish and wildlife conservation groups. Aside from the wildlife that flies through the air, wildlife on the ground may also affected by the noise pollutions generated from whirring blades. Although wind turbines can cause problems for wildlife, other things such as skyscrapers and large windows are also hazardous and continue to be built without question or similar outcry.
Wind turbines can be quite noisy, which is why they’re mostly found in very rural areas where most people don’t live. Depending on the location of the turbine, such as offshore, noise isn’t an issue. With advancements in technology, newer designs have been shown to reduce the noise complaints and have a much quieter presence.
3) Expensive Upfront Cost
If you can imagine, these massive structures are often hundreds of feet tall and require substantial upfront investment. The placement of wind turbines in rural areas requires further investment in underground lines to send power to more populated areas like towns and cities where it’s needed. The majority of the cost is the initial installation and building stage, but after that, wind energy produces an endless supply of energy as long as there is wind.
Wind energy suffers from what is called intermittency, which is a disruption caused by the inconsistency of the wind itself. Since wind can blow at various speeds, it’s hard to predict the amount of energy it can collect at a given time. This means suppliers and cities need to have an energy reserve or alternative sources of power in case the winds die down for longer lengths of time.
Harnessing wind to generate energy has its advantages and is an efficient option for many different parts of the world since it doesn’t depend on direct sunlight exposure like solar energy.
1) Free fuel
Since wind turbines themselves run strictly on the power of wind generated, there is no need for fuel. Once the turbine is complete and installed, it doesn’t need to be fueled or connected to power to continue working. This also reduces the overall cost to continue to run large-scale wind farms in comparison to other forms renewable energies, which require may require some energy investment.
2) One of the Cleanest Forms of Energy
Since wind energy doesn’t rely on fossil fuels to power the turbines, wind energy does not contribute to climate change by emitting greenhouse gases during energy production. The only time that wind energy indirectly releases greenhouse gases is during the manufacturing and transport of the wind turbines, as well as during the installation process. U.S. wind power lights homes and businesses with an infinitely available energy.
3) Advances in technology
The latest advances in technology have transformed preliminary wind turbine designs into extremely efficient energy harvesters. Turbines are available in a wide range of sizes, increasing the market to many different types businesses and by individuals for use at home on larger lots and plots of land. As technology improves, so do the functionalities of the structure itself, creating designs that will generate even more electricity, require less maintenance, and run more quietly and safely.
4) Doesn’t Disrupt Farmland Operations
Energy suppliers can build their wind turbines on pre-existing farmland and pay the farm owners to build on their property in the form of contracts or leases. This is a great boon to farmers who can use some extra income, and it wind turbine footprints take up very little space at the ground level, so it doesn’t disrupt their farm’s production. At present, less than 1.5% of contiguous U.S. land area is used by wind power plants. However, given all the plains and cattle land available on the interior of the country, there’s a lot of opportunity for expansion if landowners and government land managers are up for it.
5) Reduces Our Dependence of Fossil Fuels
Energy generated from fossil fuels not only contributes to climate change, but we’ll one day run out of it. As long as the sun heats the planet, then there’s an endless supply of wind. Furthermore, developing and investing in technology that can only run on a finite resource—that we may run out of our lifetime—is a terrible waste of human capital, private funds, and tax dollars.
source: wikipedia.org– examples.yourdictionary.com– researchgate.net– booksc.org– energy.gov– windeis.anl.gov– justenergy.com– blog.bizvibe.com– siemensgamesa.com– vestas.com– goldwind.com– ge.com– envision-group– chinawindey.com– nordex-online.com– shanghai-electric.com– csic.com– slideserve.com
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