What is wind power

Wind energy

Lexicon> Letter W> Wind Energy

Definition: Energy from winds, or (mostly electrical) usable energy obtained from it

More general terms: renewable energy

English: wind energy, wind power

Categories: electrical energy, renewable energy, basic concepts, prime movers and power plants

Author: Dr. Rüdiger Paschotta

How to quote; suggest additional literature

Original creation: July 16, 2010; last change: 04/28/2020

URL: https://www.energie-lexikon.info/windenergie.html

Winch, d. H. Air movements in the atmosphere carry large amounts of mechanical energy with them. They are mainly caused by temperature differences caused by the uneven warming of the earth's surface due to solar radiation. Ultimately, wind energy is generated from solar energy. It can be used in different ways:

  • Wind turbines (Wind turbines) “harvest” wind energy by transferring it to a rotating axle, which is then usually used to drive a generator to generate electrical energy. In the past many windmills were used; H. windmills driven by windmills. This had the advantage that it hardly matters when exactly enough wind is available to grind the grain. However, the generation of electricity in wind turbines offers far more diverse application possibilities.
  • Sailing ships use wind energy directly to propel them. In the future, similar technologies could be used more and more on ships, especially on large transport ships. Traditional forms of sails do not necessarily have to be used for this, but instead use e.g. B. also Flettner rotors or stunt kites.
  • There are novel concepts for the use of wind energy. B. based on dragons. Either a rotor with generator is operated on a kite (possibly at a high altitude where there are strong and steady winds) and the electrical energy is conducted downwards via a cable, or the pull of the kite is used to drive a winch on the ground . Such concepts are currently being tested and are not yet ready for use.

The absolutely dominant form of wind energy use is that with wind energy plants (wind power plants) based on wind turbines. Three-bladed rotors have become widely accepted, with a wide range of outputs from less than one kilowatt to several megawatts. So far, such systems have largely been built on land (onshore), but increasingly offshore systems (on the sea) are being planned and built, as they can be used to develop large areas with very good wind conditions and without disturbing the landscape. The article on wind turbines contains more details on this.

The electrical power generated by a wind turbine depends very much on the wind speed. In essence, it is proportional to the third power of the wind speed, i.e. H. it becomes eight times greater when the wind speed is doubled. It follows from this that the quality of a wind energy location is very important for the energy yield and thus for the financial and energetic amortization period.

Wind energy is one of the renewable energies. It does not produce any dependence on dwindling fossil fuels and no exhaust gases, in particular no climate-damaging carbon dioxide emissions, apart from moderate emissions from gray energy in connection with the construction of the plants. (The energetic amortization period is usually only a few months.) Overall, the use of wind energy is very environmentally friendly, even if problems with noise pollution or the killing of birds occasionally occur. It should be noted that objections in connection with landscape protection, noise problems or bird protection are sometimes irrelevantly motivated and certain problems are often deliberately dramatized. For example, hazards to birds should be adequately compared with those from vehicles, buildings and power lines; the result is that wind turbines would only cause a tiny fraction of the total human-caused bird kills, even in the event of massive future expansion.

In Germany, wind energy is the renewable energy with the fastest increase in generation capacities. In 2010 it already covered almost 10% of total German electricity generation, while it was only a little more than 1% worldwide. The countries with the largest generation capacities (maximum output, as of 2011) are China (63 GW), the USA (47 GW), Germany (29 GW), Spain (22 GW) and India (16 GW).

Fluctuations in wind power production; Security of supply aspects

The number of annual full load hours provides information on how evenly the wind energy is generated.

Naturally, the strength of the wind at a location changes greatly with the respective weather conditions. Since the power generated also depends very strongly on the wind speed (see above), the power generated fluctuates very strongly. On an annual average, a wind turbine in good onshore locations generates significantly more than 2000 full load hours per year (i.e., on average, a good 20% of the maximum output), and less in less favorable locations. (Well over 3000 full load hours are possible offshore.) This practically excludes the direct supply of consumers with wind energy alone. In Germany, only around 6% of the installed system capacity can currently be regarded as secured power plant capacity from wind power. There are various approaches to balancing the currently generated and required electrical power: the combination with other power generation systems, the use of energy storage (both also for generating control energy), increased load management and the expansion of power grids. These approaches are discussed in detail below. Planning the use of power plants is made considerably easier thanks to the meanwhile quite precise wind power forecasts (e.g. over three days), which are based on improved forecasts of the weather.

The combination of many wind turbines reduces the relative fluctuations in the power generated.

An important fact is that the relative fluctuations in power generation can be greatly reduced when many wind turbines are combined if these systems are geographically distributed as well as possible. Then the local fluctuations are largely balanced out. If, for example, a cold front moves across Europe, the plants in the west benefit first from strong winds, and only later those in the east. Instead of a sharp point, as can be seen in the generation of each individual system, one receives a contribution to the total electricity generation that is strongly stretched over time. However, when averaging over longer periods (e.g. one month each time), the production of plants within Central Europe is much more strongly correlated. A good balance on such time scales can only be achieved if larger geographical areas are included. For example, wind farms in north-west Africa could produce more electricity in summer and thus complement the higher production in central Europe in winter. This would be possible if a European supergrid were set up that also includes North Africa.

Technical failures of individual systems are unproblematic for the security of supply. At most, a few megawatts are missing, while the failure of a large power plant can affect more than one gigawatt.

Combination with other power generation systems

Wind turbines can be combined with other power generators (especially power plants), the output of which can be easily regulated. This works particularly well with storage hydropower plants. These can completely replace wind energy when there is no wind, as the water turbines can have very high outputs. However, the capacities are e.g. B. bounded by reservoirs; however, they can be saved at times when sufficient wind power is available. In some cases, these capacities are even replenished in the event of excess electricity; one then speaks of pumped storage power plants.

Wind energy makes little contribution to the guaranteed output, but it expands the available amounts of energy and in this respect contributes very well to the security of supply.

Hydropower and wind power then make a complementary contribution to the reliability of the electricity supply: hydropower guarantees that the output is guaranteed at all times, while wind turbines can greatly expand the total amount of energy available per year. It is then irrelevant whether wind energy is available at a certain point in time; Problems would only arise if there was a lull in wind for a very long time. If the storage capacity of hydropower is high enough, such problems become arbitrarily unlikely. Incidentally, the fact that wind power generation in Europe is typically higher in winter, when water capacities are most likely to become scarce and consumption is high, has a positive effect.

Gas power plants, for example in the form of large gas and steam combined cycle power plants, are also well suited for combination with wind energy. The performance of these can be changed relatively quickly, and the saving of natural gas in times of good winds is very welcome.

Even small biogas-fired combined heat and power plants can partially be operated with electricity and thus contribute to load management. The situation here is similar to that with the combination of wind and water: biogas guarantees the power currently required, but only a limited amount of energy, while wind energy increases the total amount of energy available.

Coal power plants and nuclear power plants are poorly suited to be combined with wind energy.

Coal power plants and nuclear power plants are hardly suitable. Although these can also be adjusted in terms of performance (especially with appropriate technical optimization), however, only to a limited extent, often with considerable losses in efficiency, and in coal-fired power plants possibly also with a reduced effectiveness of the exhaust gas cleaning system. In addition, the savings in fuel costs are lower than z. B. in gas power plants.

Use of memories

Load management

Some electricity consumers can be operated in a targeted manner if enough wind power is available. In other cases, the operation is normally continuous, but can be interrupted remotely if there is a particular shortage of electricity (Load shedding). Such load management techniques (Demand side management) are used in some industrial systems, for example in electrolysis systems or systems for the production of liquid nitrogen, but also in electric storage heaters. The required flexibility of the consumer can be rewarded with correspondingly lower electricity tariffs.

Power grids

The more the transmission networks are developed, the easier it becomes to use locally generated surpluses elsewhere. This approach is particularly energy efficient and inexpensive. However, its implementation takes a relatively long time.

Overall rating

The time fluctuations in electricity generation by wind turbines is definitely a major disadvantage of this technology. However, this issue should not be overly dramatized. In particular, the use of wind energy in large interconnected networks such as B. the European is relatively unproblematic, except if a high proportion of wind energy in the total electricity generation (e.g. more than 25%) should be realized. (For comparison: In 2016, around 12% of the electricity in Germany was generated by wind turbines.) This topic was examined in detail in the dena network study [6]. It was concluded that a targeted expansion of various high-voltage lines is necessary and that with further expansion a certain increase in the demand for control energy is to be expected, this control energy can, however, be taken over by existing power plants for the time being. The costs of the required additional network expansion (approx. 5% of the network investments previously made annually) as well as the additional costs due to the EEG feed-in tariffs and for the adapted operation of the power plant park (with additional control energy and reserve energy) were comprehensively determined. For the expected additional costs due to the funding allRenewable energies in Germany one determined z. B. for 2015 a value of approx. 1 ct / kWh for the non-privileged consumers (which corresponds to approx. 5% of the end-consumer price) and much less for the privileged bulk consumers. Around a third to half of the above-mentioned additional costs are attributable to wind energy, which in 2015 should already cover 15% of all German electricity generation. These costs are therefore quite moderate, although additional positive financial aspects from the additional employment and tax revenues have not yet been taken into account.

It should be noted that expansion of the transmission network also benefits the stability and flexibility of the network as a whole, e.g. B. as part of the integration of additional hydropower capacities from Northern Europe. The entire electricity trade should benefit from this.

Profitability of wind energy

The costs of wind power essentially depend on three factors: the performance-specific construction costs, the service life of the systems and the quality of the location. There is steady progress in the first two fields, so that costs have been falling steadily and significantly for years. (The steady degression of the state-guaranteed remuneration rates also forces significant progress.) Compared to the generation costs of conventional power plants, they are usually significantly higher, which is why the wind energy boom that has occurred in recent years only through state support (priority feed-in, statutory purchase obligation, fixed remuneration) became possible.

The remaining gap in generation costs between wind energy and fossil energy is likely to shrink further in the next few years, as the costs of wind energy continue to fall, while on the other hand fossil fuels are becoming more expensive and new nuclear energy projects are also becoming much more expensive. Another factor is the expected CO2-Taxes in increasing amounts, which increasingly reflect (internalize) the external costs of fossil fuel power plants (at least those caused by climate hazards) financially. With the introduction of CCS technology for coal-fired power plants at the latest, wind power should be cheaper than coal power.

The first wind energy projects in Germany are already doing without subsidies!

For these reasons, it is to be expected that wind power will be able to compete economically in the near future without government subsidies. B. the European power supply can take over. The first offshore wind energy projects are already being planned that will get by without any subsidies. It is also to be hoped that, particularly in the USA, China and India, many coal-fired power plants can be replaced by wind turbines, which is urgently needed in the context of climate protection.

When it comes to Africa, one often thinks of solar energy, although wind energy is particularly interesting in North Africa.

The exploitation of previously largely unused potential in Northwest Africa, where very low electricity generation costs would be possible due to excellent locations, appears particularly interesting. With a supergrid, efficient long-distance transport would also be possible without excessive energy losses and at low costs. Since there would be more wind power generated there in summer, it would also be a good complement to wind power from the north, which is increasingly generated in winter. The generation costs would be considerably lower than those for solar energy.

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See also: wind turbine, wind farm, renewable energy, security of supply, full load hours, renewable gas
as well as other articles in the categories of electrical energy, renewable energy, basic concepts, prime movers and power plants