Wind energy: frequently asked questions

In a few years’ time renewable energies will be the most important energy sources in Germany. Wind energy forms the backbone of the energy revolution.

In comparison to fossil fuels, as well as other renewable energy sources, wind energy is the most economically efficient way of generating electricity. Wind turbines already produce energy more cost-efficiently than new fossil fuel power stations. Moreover, in contrast to finite energy resources such as coal, oil and gas, wind energy is available on an unlimited basis. If we factor in the consequential costs of final disposal for nuclear, or the detrimental impact on the environment and health from fossil fuel sources, onshore wind energy can be shown to be the cheapest source of energy available today.

92 per cent of Germans endorse increased development of renewable energies, according to a representative survey conducted by TNS Emnid (2014). Despite this affirmation and its potential as an environmentally friendly alternative to energy sources that harm the environment, in many places in Germany the planning and installation of wind energy projects is accompanied by mistrust, fears and concerns.

Yet is there actually any truth in the perceived threat for people, animals and the environment? We have put the most important assertions about wind energy under the microscope to enable you to form your own opinion on the subject based on empirically proven figures and facts:

Myth 1: wind turbines endanger the environment

  • Wind turbines kill large numbers of birds and bats.

    Incorrect: although building wind turbines, like any form of energy generation, is a form of interference in nature, numerous studies have repudiated the accusation of “bird strikes”. Further research is needed into the impact of wind energy on bats. It is only on a very few wind farms that increased numbers of corpses have been found.

    Besides this, climate protection also means protecting nature and its species. Climate change is shown to lead to significant changes in behaviour in birds. Wind energy is the driving force of the energy revolution, of the largest climate protection programme in history.

    Up to five birds a year fall victim to a wind turbine. Around 150,000 birds on average die due to the circa 28,200 wind generators installed in Germany (2016 figures).

    120 times more birds are put at risk by glass façades on buildings. 18,000,000 birds die each year in Germany after colliding with glass.

    • Further information

      As part of the site selection and authorisation process checks are carried out to assess the possible impact of wind generators on the habitat of birds.

      Conservation areas as well as breeding and resting zones for birds are generally not considered as possible sites. Where wind generators are located in birds’ migratory corridors the turbines must be switched off as required (e.g. in gusty weather conditions) in order not to put the birds at risk.

      During the wind turbine planning process the following therefore applies: negative consequences on affected populations can be minimised or even avoided altogether by carrying out extensive investigations, selecting a good site, taking suitable precautions and sustainable compensation measures.

      Results from research carried out by ornithologists over many years also show that, besides this, only the behaviour of a few species is negatively affected by wind turbines.

      Conversely: since 1990 the population of white-tailed eagles has grown in parallel with the construction of onshore wind energy, especially in Lower Saxony, Schleswig-Holstein and Brandenburg – that is, in the German Länder with the most wind turbines.

    • Research

      Kohle, O. (2016). Windenergie und Rotmilan/Mäusebussard. Ein Scheinproblem. Available in german at: www.hans-josef-fell.de/content/index.php/dokumente/studien-und-analysen/912-windenergie-und-rotmilan-maeusebussard-ein-scheinproblem/file

      Hauff, P. (2009). Zur Geschichte des Seeadlers Haliaeetus albicilla in Deutschland, Linz/Austria 2009, S. 11; available in german at: issuu.com/hinschethomas/docs/geschichte_des_seeadlers_in_deutschland

      National Environmental Research Institut (2005). Avian collision risk at an offshore wind farm, Biodiversity, Denmark.

      Bundesverband WindEnergie (2005). Vogelschutz und Windenergie, BWE-Hintergrundpapier (5).

      Swedish Energy Agency (2005). The Impact of Offshore Wind Farms on Bird Life in Southern Kalmar Sound - Sweden.

      Michael-Otto-Institut im Naturschutzbund Deutschland (2004), Auswirkungen der regenerativen Energiegewinnung auf die biologische Vielfalt am Beispiel Vögel. Fakten, Wissenslücken, Anforderung an die Forschung, ornithologische Kriterien zum Ausbau von regenerativen Energiegewinnungsformen.

      Bund für Umwelt und Naturschutz Deutschland (2004). Vögel und Fledermäuse im Konflikt mit der Windenergie Erkenntnisse zur Empfindlichkeit. Bremer Beiträge für Naturkunde und Naturschutz, Heft 7.

      Arsu GmbH (2004). Langzeituntersuchung zum Konfliktthema „Windkraft und Vögel“, 3. Zwischenbericht Oldenburg.

      Büros für faunistische Fachfragen Linden, Matthias Korn u.a. (2003). Stellungnahme Regionalplan Oberpfalz-Nord – Ausschusskriterien für Windenergieanlagen im Vorkommensgebietgefährdeter Großvogelarten.

      Technische Universität Berlin (2002). Windenergie und Vögel – Ausmaß und Bewältigung eines Konfliktes (Tagungsband).

      Frank Bergen (2001). Untersuchungen zum Einfluss der Errichtung und des Betriebs von Windenergieanlagen auf Vögel im Binnenland (Diss.), Bochum.

      Ihde, S. u.a. (1999),Vogelschutz und Windenergie – Konflikte, Lösungsmöglichkeiten und Visionen, Osnabrück. Available in german at: www.bund-rvso.de/windenergie-windraeder-voegel-fledermaeuse.html

  • Wind turbines harm wild animals and livestock.

    Incorrect: there has been no evidence so far to suggest that animals in nearby paddocks, pasture or stables suffer from behavioural issues on account of the wind turbines being in operation. Wild animals, too, quickly become accustomed to the turbines rather than seeing them as a threat.

    • Further informationen

      Research and surveys of German hunters show that neither small game such as foxes or rabbits nor deer are troubled by the wind turbines and that they do not eschew their habitat because of them. Studies have not yet been carried out into the effects on big game; however experience suggests that the effects here are similar.

      The construction of wind turbines is, on the other hand, often bound up with a revaluation of the animals’ habitat. A new source of food can, for example, be created by planting over the base of the foundations. The paths that are necessary for construction are also often refashioned afterwards, often using deciduous trees. This increases levels of biodiversity in monocultures.

    • Research

      Arnett, E. B. (Bat Conservation International Technical Editor and Project Coordinator) (2005). Relationships between Bats and Wind Turbines in Pennsylvania and West Virginia.

      Sedding, A. (2004). Windenergieanlagen und Pferde. Gutachten, Bielefeld.

      Hensen, F. (2004). Gedanken und Arbeitshypothesen zur Fledermausverträglichkeit von Windenergieanlagen.

      Elsam Engineering A/S (2004). Horns Rev. Annual status report for the environmental monitoring programme (1.1.–31.12.2003), Fredericia.

      Institut für Wildtierforschung an der Tierärztlichen Hochschule Hannover (2001), Projekt „Windkraftanlagen“. Raumnutzung ausgewählter heimischer Niederwildarten im Bereich von Windkraftanlagen, Hannover.

  • Wind turbines destroy semi-natural forests.

    Incorrect: wind energy projects are implemented in intensively managed commercial forests that represent a cultivated landscape that has already been shaped by people. Semi-natural and vulnerable areas are excluded from the choice of wind energy locations.

    Areas cleared as part of the construction process are also subject to stipulated compensatory measures – e.g. reforestation or forest restructuring measures. For every square metre of cleared forest another is planted at other locations on a 1:1 basis.

    Every fifth new turbine in Germany is installed in a forest setting. If we compare Germany's Länder we see that Baden-Württemberg and Rhineland-Palatinate have the most forest-based wind generators with a quarter of turbines are already situated in forest locations.

    Every fifth new turbine in Germany is installed in a forest setting. If we compare Germany's Länder we see that Baden-Württemberg and Rhineland-Palatinate have the most forest-based wind generators with a quarter of turbines are already situated in forest locations.

    • Further informationen

      Even if building wind turbines always represents an intervention in nature, forests possess great potential for the development of wind energy. They offer both the necessary designation of new areas for the energy revolution as well as protection for inhabitants. The trees in a forest offer effective, natural privacy, screening the turbine from sight. Towers and rotors are hardly noticeable at close range thanks to being shaded from view by the trees.

      The natural background noise of the forest usually blocks out that from the wind turbines. The 140 metre high tower ensures that the yield-diminishing turbulence of the treetops is virtually eliminated. The rotors are situated in an air layer that is characterised by high wind velocities – which makes energy generation in a forest extremely effective and economical.

      The respective heights of the Black Forest and the Swabian Alb record the highest wind speeds in Baden-Württemberg. In order to be able to utilise this potential in harmony with nature UKA works together with both nature conservation authorities and the forestry office responsible when it comes to planning wind energy projects. Nature conservation reports ensure that any adverse effects on plants and animals are minimised as far as possible.

      We continue to look after the forest after using it for wind energy, too: decommissioned turbines must be dismantled and may not be left to decay as ruins in the landscape. The entire wind turbine is removed; the foundations are dug out to a depth of 1.2 metres; holes are filled in with fill soil and topsoil is added on top.

      If wished, paved access routes can also be removed. The turbine operator’s declaration of commitment regarding this dismantling process is incorporated during the initial planning phase as a condition of admissibility required in order to attain an operating licence in the first place.

    • Research

      FA Wind (2016). Entwicklung der Windenergie im Wald - Ausbau, planerische Vorgaben und Empfehlungen für Windenergiestandorte auf Waldflächen in den Bundesländern. Available in german at: www.fachagentur-windenergie.de/fileadmin/files/Veroeffentlichungen/FA-Wind_Analyse_Wind_im_Wald_06-2016.pdf

Myth 2: wind energy is dangerous and makes you sick

  • Wind turbines are loud and disturb residents.

    Incorrect: modern wind turbines have been developed to be noise-minimising: they have sonically optimised rotor blades, which allows them to emit less noise. Moreover, ambient noise such as road noise, the rustling of leaves on the trees or everyday sounds overlay the noise emitted by wind turbines.

    The whirring noise caused by the rotor blades is already imperceptible from just a few 100 metres away. In addition, work is going on to minimise light emissions caused by the obstruction lighting for the turbine. Besides this, legal provisions governing the planning phase mandate that residents are protected from shadows being cast on their homes.

    45 dB(A) amounts to the noise exposure of a modern wind turbine at a distance of 200 metres. That is 5 dB(A) less than, for example, the hum of a fridge.

    By contrast, sitting in a car moving at 100 km/h a person is exposed to 100 dB(A).

    • Further information

      Noise

      When it comes to wind turbines there are two sources of noise: noise from the mechanical components such as gearboxes and generators, and the aerodynamic sound emitted by the movement of the rotors. The Technical Instructions on Protection Against Noise (Technische Anleitung zum Schutz gegen Lärm, TA-Lärm DIN ISO 9613-2) stipulates the extent to which these may be audible. The limit values lie between 35 dB(A) in residential areas and 45 dB(A) in mixed-use areas. A minimum distance from the nearest housing development must be maintained in accordance with this. To gain building approval, an independent report must be conducted to document that these values have been adhered to.

      Lighting

      Currently a wide variety of methods is being tested and explored to minimise still further any visual interference by wind turbines – particularly through the use of obstruction lighting. This has been defined in the General Administrative Rules for the Identification of Aircraft Obstructions (Allgemeine Verwaltungsvorschrift zur Kennzeichnung von Luftfahrthindernissen (AVV)) since 2004. Identifying the turbines during daylight hours can be achieved through the use of coloured markings and/or white lighting. During the hours of darkness German regulations stipulate that only red flashing lights may be used for this purpose. In future, however, it will be possible to utilise radar systems to signal to the wind turbines in good time that an aircraft is approaching. The rest of the time the flashing lights can then be switched off. Another option is to direct the light signal downwards, or to adjust the strength of the light according to visibility.

      Overshadowing

      According to the guidelines set out by the Federal/State Working Group on Light Imission (Arbeitskreis Lichtimmissionen der Bund/Länder-Arbeitsgemeinschaft Immissionsschutz), the shadow cast by wind turbines may not overshadow a dwelling for more than 30 hours a year and 30 minutes a day. The construction or Federal Immission Control Act (Bundes-Immissionsschutzgesetz) authorisation stipulates that the turbine must be equipped with an automatic shut-off control in this case. The limit value is the result of a theoretical maximum possible shadow area. The duration calculation is based on ideal conditions: if the sun were to shine constantly, the rotor to turn non-stop and if it was always positioned cross-ways to the sun. In real conditions at a site with a hypothetical shadow duration of 30 hours per year we can assume an actual shadow duration of eight hours per year. An automatic shut-off control is used to ensure that the period of overshadowing is restricted to these eight hours per year.

    • Research

      Deutscher Naturschutzring DNR (2005). Umwelt- und Naturverträgliche Windenergienutzung in Deutschland (onshore) – Analyseteil, Lehrte.

      Landesumweltamt Nordrhein-Westfalen (2002). Windenergieanlagen und Immissionsschutz (Materialien Nr. 63), Essen.

      Gesetz zur Umsetzung der UVP-Änderungsrichtlinie, der IVU-Richtlinie und weiterer EG-Richtlinien zum Umweltschutz, BGBl. I, Nr. 40 vom 2.8.2001.

      Sechste Allgemeine Verwaltungsvorschrift zum Bundes-Immissionsschutzgesetz (Technische Anleitung zum Schutz gegen Lärm – TA Lärm) vom 26. August 1998, GMBI 1998, S. 503-515

      Fördergesellschaft Windenergie (1998). Technische Richtlinien zur Bestimmung der Leistungskurve, des Schallleistungspegels und der elektrischen Eigenschaften von Windenergieanlagen, Brunsbüttel.

  • The infrasound from the wind turbines causes illness.

    Incorrect: scientific studies show that infrasound only has consequences for humans if it can be heard or felt. No negative effects have been identified under this perceptibility threshold. The infrasound generated by wind turbines does not reach this perceptibility threshold even at close range, making it non-hazardous.

    The perceptibility threshold defines noise levels above 20 Hz and 130 dB of sound pressure. The background noise produced by wind turbines is considerably less than this.

  • In severe, stormy weather wind turbines simply fall over.

    Incorrect: as with any technical structure the risk of accident can never be categorically ruled out, however it is extremely small. Should malfunctions still occur these would only affect the immediate vicinity. Homes and residential areas are never at risk, thanks to the legal provisions on required distances.

    • Further information

      The foundations of onshore wind turbines are modified to suit the conditions on the individual site. Spread foundations made from concrete and steel are most commonly used. When the subsoil is weak piled foundations are also used. The foundation secures the turbine against sinking or falling over.

      Other potential hazards are largely eliminated in modern turbines: burning off caused by lightning strikes is nowadays virtually impossible thanks to lightning and surge protection. Furthermore, specialised ice sensors and rotor blade heaters can prevent ice being released from the blades in winter or in cold regions. Other fault scenarios can be identified early on by automatic, computer-controlled management systems.

    • Research

      Seifert, H. (2005). Eiszeit am Standort, DEWI Magazin, 2/2005

      Seifert, H. (1996). Rotorblätter eiskalt erwischt, DEWI-Magazin, 2/1996

      Gesamtverband der deutschen Versicherungswirtschaft (2003). Gesamtüberblick über den technologischen Entwicklungsstand und das technische Gefährdungspotenzial, 3/2003.

Myth 3: wind turbines disfigure the landscape

  • In Germany wind turbines are built at random.

    Incorrect: even when still in the planning phase the wind energy project must overcome all manner of legal hurdles to obtain building approval. Right from the off, all the relevant authorities, local organisations and associations are informed of the plan and they can then influence the process. Since 1 July every wind turbine must receive individual authorisation.

    It takes five years on average to move from project development to operation. It takes a little over four years for the turbine to receive authorisation.

    • Further information

      With the help of the local urban land use plan and preparation of a land use planning process or development plan communities can create priority areas for wind energy and thus manage and control construction in a focused way. In this urban land use plan citizens can get involved and express their opinions in the early stages of public participation. In many parts of Germany the regional planning authorities take over the process, with the involvement of local communities, ensuring a regulated spatial distribution of the wind turbines.

      Alongside existing legal provisions the planning authorities can also stipulate their own criteria for the construction of wind turbines, such as, for example, a greater distance from housing developments. Conservation areas and regions of special cultural and historical worth are excluded from the areas in which wind turbines can be installed and operated. Furthermore, investigations are also carried out into the local conditions – such as housing, animals and plants – as part of the authorisation process.

      Planning is subject to the regulations of the Building Code (Baugesetzbuch) and the Federal Immission Control Act (Bundes-Immissionsschutzgesetz), the Federal Nature Conservation Act (Bundesnaturschutzgesetz) and the law regarding the impact on environmental sustainability.

    • Research

      Fachagentur Windenergie an Land (2015). Dauer und Kosten des Planungs- und Genehmigungsprozesses von Windenergieanlagen an Land. Available in german at: www.fachagentur-windenergie.de/fileadmin/files/Veroeffentlichungen/FA-Wind_Analyse_Dauer_und_Kosten_Windenergieprojektierung_01-2015.pdf

      Änderung der 4. Bundesimissionsschutzverordnung zum 1.7.2005, BWE-Hintergrundpapier, 6/2005.

      Baugesetzbuch (BauGB)

      Bundesemmissionsschutzgesetz (BimSchG)

      Bundesnaturschutzgesetz (BNatSchG)

      Gesetz über die Umweltverträglichkeitsprüfung (UVPG)

  • Wind turbines put off tourists.

    Incorrect: wind generators change the look of the landscape. Of course, this will not please everyone. So far, however, there is no significant evidence that wind turbines have a negative effect on tourism. Empirical surveys conducted by tourism research institutes have demonstrated this sufficiently.

    99 per cent of those surveyed in the Analysis of the Influence of Renewable Energies on Tourism in Schleswig-Holstein (Einflussanalyse Erneuerbarer Energien und Tourismus in Schleswig-Holstein) (2014) indicated that the look of the landscape was not a reason for staying away from a holiday destination in future.

    94 per cent of visitors feel generally unaffected by the wind turbines.

    • Further information

      Studies have shown that, in fact, although some tourists dislike wind turbines in the landscape to a greater or lesser degree, for the most part this would not deter them from selecting a particular holiday destination. Even regions on the North Sea and Baltic Sea are continuing to see increasing visitor numbers, despite the wind turbines built there over the past few years.

      Surveys have even shown that wind turbines give the adjacent municipalities a positive, ‘green’ image and can thereby promote new forms of tourism. This has resulted, for instance, in a special travel guide by Baedeker: “Deutschland. Erneuerbare Energien entdecken” (Germany. Discover renewable energy.) Wind turbines are consequently not just the carthorse of the energy revolution but also a popular attraction for holidaymakers.

    • Research

      NIT Institut für Tourismus- und Bäderforschung in Nordeuropa GmbH (2014). Einflussanalyse Erneuerbare Energien und Tourismus in Schleswig-Holstein.

      Institut für Regionalmanagement (2012). Besucherbefragung zur Akzeptanz von Windkraftanlagen in der Eifel.

      Offshore-Park Nysted ist eine Touristen-Attraktion, Ostsee-Zeitung, 11.09.2004.

      Windkraft-Tourismus, neue energie, Heft 7/2004.

      Ostseeinstitut für Marketing, Verkehr und Tourismus an der Universität Rostock (2003). Wirkungseffekte von Offshore-Windkraftanlagen in Mecklenburg-Vorpommern auf touristische Nachfrage- und Angebotsstrukturen.

      Soko-Institut GmbH (2003). Windkraftanlagen und Tourismus. Bevölkerungsumfrage, Bielefeld.

      Institut für Tourismus- und Bäderforschung in Nordeuropa GmbH N.I.T. (2000). Touristische Effekte von On- und Offshore-Windkraftanlagen in Schleswig-Holstein, Kiel.

  • Wind turbines reduce quality of life and lead to losses in the value of land and property.

    To date there is no proof that wind turbines have a direct, negative long-term effect on property prices.

    • Further information

      It is often claimed that property near the wind farm could suffer a permanent drop in value, even when legal immission values and minimum distances to residential areas are complied with. In actual fact, the value of properties is determined by a variety of different factors. The presence of wind turbines is only one factor in this mix.

      Just how big an impact this factor has depends on the requirements of the potential buyers of the properties. Demand determines the price. Factors such as the proximity to conurbations or the infrastructure locally play an increasingly important role in times of urbanisation – especially in rural areas in which wind generators are also often present. Studies from East Frisia and Aachen have shown that there can be a positive impact on property prices in areas with a high density of wind generators. By creating jobs, influx or the possibility of involvement in a citizens’ wind farm project this can create values in economically underdeveloped regions.

      Local businesses, too, can get involved in the construction of the wind farm or in carrying out compensatory measures (e.g. reforestation, renaturation of water networks). In many cases citizens who live near wind farms are, moreover, granted access to opportunities for financial involvement.

      Furthermore, the revenue that property owners gain from hiring and leasing land for wind turbines can offer young families the chance to take on a job with lower earning potential in their home town rather than moving to a bigger city. This enables them to actively counteract the cycle of migration and property price falls in rural areas.

    • Research

      Stadt Aachen (2011). Untersuchung: Hat der Windpark „Vetschauer Berg“ Auswirkungen auf den Grundstücksmarkt von Wohnimmobilien in den Ortslagen Vetschau und Horbach. Available in german at: www.windenergie.at/MEDIA/Studie%20Immobilienpreise%20und%20Windenergie%20Aachen.pdf [10.02.2017].

      Troff, Herbert (2013).Einflüsse von Windkraftanlagen auf den Wert von Immobilien und Grundstücken. Available in german at: www.energieagentur-goettingen.de/fileadmin/files/downloads/131022_Troff_Wertentwicklung_Immobilien_01.pdf

Myth 4: wind energy harms the economy and wastes resources

  • Wind energy puts jobs at risk.

    Incorrect: wind energy is a driver of jobs: 371,400 people are currently employed in Germany in the renewable energy sector. The wind energy segment accounts for the largest proportion of 37 per cent, equating to 137,800 employees. 119,000 of these work in onshore wind energy. The number of people employed by the sector has more than doubled in the last 10 years.

    Forecasts predict that, by 2030, there will be 500,000 people employed in the renewable energy sector in Germany.

  • Wind turbines demonstrate a negative eco-balance.

    Incorrect: an onshore wind turbine generates enough energy within the space of three to twelve months to cover that required for its production, operation and disposal. With an average operational life of 20 years the resulting economic and ecological balance is an overwhelmingly positive one.

    One wind turbine generates 40 to 70 times as much energy during its lifetime as is required to manufacture, operate and dispose of it.

    • Further information

      A 3 MW wind turbine generates around 180 million kilowatt hours over the 20 years it is in operation. This can cover the energy requirements of approx. 2,600 three-person households a year. Three square metres of a wind turbine’s rotor surface area can therefore cover the annual energy requirements of a family of four – in total the rotor surface area (e.g. of the Vesta V126 model turbines) measures 12,469 square metres.

    • Research

      BWE-Service GmbH (2005). Windenergie Marktübersicht, Osnabrück.

      TÜV-Verlag (2000). Nutzung der Windenergie, Karlsruhe.

      Institut für Energiewirtschaft und Rationelle Energieanwendung (2007). Lebenszyklusanalyse ausgewählter Stromerzeugungstechniken, Stuttgart.

      Fachhochschule Würzburg (2004). Energetische Bewertung von Windkraftanlagen (Diplomarbeit), Würzburg.

      Ruhr-Universität (2004). Ganzheitliche Energiebilanzen von Windkraftanlagen: Wie sauber sind die weißen Riesen?, Bochum.

      Kaltschmitt, M. u.a. (2003). Erneuerbare Energien – Systemtechnik, Wirtschaftlichkeit, Umweltaspekte, 3. Auflage, Berlin.

  • Wind turbines cannot be disposed of practically.

    Incorrect: modern wind generators can be almost entirely recycled. The feasible recycling quota is between 80 and 90 per cent.

    Including its gearbox, tubular steel tower and foundation a wind turbine consists of:

    • 60 per cent reinforced concrete
    • 30 per cent steel
    • 2 per cent glass fibre reinforced plastic
    • as well as small quantities of copper, aluminium, electronic components and fluids required for operation.
    • Further information

      The rotor blades, which are constructed from glass fibre reinforced plastic, can be shredded or pulverised. The material can be admixed when manufacturing new rotor blades; used as a filling material in plastics; or the glass fibre components can be reused in cement mixes.

      Where transport routes prove to be uneconomic it can alternatively be used as fuel in a combustion plant. The concrete from the foundation can be used as aggregate in road-building. Electronic waste is recycled in refineries and the metallic components melted down in foundries.

      These components from the nacelle, the rotor hub and the generator are especially valuable and therefore economically feasible to recycle. If the turbines used are not recycled they occasionally have a second operational life in sites in other countries.

    • Research

      Mühlenabbau – für ein 2. Leben oder die Entsorgung?, Erneuerbare Energien, Heft 6/2004.

      Perspektiven eines Recycling von Windkraftanlagen, DEWI Magazin, August 1995.

Myth 5: wind power is unreliable

  • Too often wind generators do not turn.

    Incorrect: the operational duration of a wind turbine is between 7,000 to 8,000 hours a year – this equates to a utilisation capacity of 85 per cent. Some sites reach full capacity at up to 2,000 hours a year. A high yield is still achieved even with only partial performance.

    • Further information

      Modern wind turbines work effectively at moderate rotational speeds. At a wind speed of 2.5 metres per second electricity is generated and fed into the local network. In severe storms with wind speeds of 25 to 34 metres per second the turbines are slowed to prevent damage to the wind generators, but also to avoid overloading the network. This is necessary on account of the lack of grid expansion in strong winds. (See Myth “Wind generators offer no guarantee regarding basic supply.”)

      Other causes for the rotors being at a standstill include maintenance work or repairs; protecting birds and bats during breeding or migration seasons; as well as protecting residents.

  • Wind generators offer no guarantee regarding basic supply.

    Incorrect: precise calculations as to the temporal and local supply of wind power can be made on the basis of meteorological forecasts. This allows drops in performance and surpluses to be evened out across the power grid regionally, nationally and across Europe.

    Furthermore, other renewable energy facilities, such as hydroelectric power stations, biogas plants and geothermal power plants, supplement the green energy mix.

    In 2015 the circa 28,200 wind generators in Germany delivered 12.3 per cent of the electricity generated. Around 27,270 of these are onshore turbines.

    • Further information

      In order to rely entirely on renewable energy in future the power grid needs to be expanded further. Network operators are committed to this objective in accordance with the German Renewable Energy Sources Act (Erneuerbare Energien Gesetz (EEG)).

      Only then can individual fluctuations in the electricity feed from wind and solar energy be addressed and the electricity distributed nationally and internationally. This means that, even in strong winds, it is no longer necessary to switch off the wind generators due to the risk of overloading the networks.

    • Research
  • It is not economically viable to store wind energy.

    Thanks to meteorological forecasts it is currently possible to store electricity generated by wind power as needed. By managing the energy production and demand the electricity grids can successfully be kept at a stable level despite fluctuations in availability. In addition, in practice many different storage methods have already been researched and tested.

    • Further information

      Various solutions are currently in the process of being tested:

      • The pumped-storage power plant at Geesthacht, which will be used specifically as the mechanical storage facility for North German wind energy
      • A battery storage system in Schwerin that will secure the network frequency in West Mecklenburg
      • The power-to-heat method that will store wind energy as heat for use as heat supply
      • The power-to-gas method, which involves converting electricity into hydrogen and subsequently into methane – a substance that is almost identical to natural gas
    • Research