Home » Wind Power for the Transition at Coal Sites – Prospects and Problems

Wind Power for the Transition at Coal Sites – Prospects and Problems

Wind power is one of the politically prioritised options for the energy transition to climate neutrality at coal sites, although the use of “Carbon Capture and Storage” (CCS) technology during coal-burning operations is also a possible method for the reduction of CO2 emissions. Wind power is undergoing impressive technological and economic development, and its expansion enjoys a high priority in energy and climate policy, especially in Germany. Indeed, former coal sites often offer relatively favourable conditions for wind turbines. A more detailed examination reveals that the choice of locations for wind turbines requires quite a differentiated analysis of the various regions, one that takes into consideration multiple factors ranging from wind conditions to residents’ concerns to the geology of the subsoil. If major contributions to energy management and employment are to be obtained, however, a daunting number of turbines must be built, creating environmental issues and entailing the use of enormous land areas and tremendous consumption of raw materials.

Authors/Autoren: Prof. Dr. Kai van de Loo, Julia Haske M. A., Forschungszentrum Nachbergbau (FZN), Technische Hochschule Georg Agricola (THGA), Bochum/Germany

Energy transition, coal exit and wind power expansion as an alternative?

The coal exit heads the agenda for the politically sought and managed energy transition for the achievement of climate neutrality by 2045 (Germany) or 2050 (EU) – commonly known in Germany as the energy transition – and in some other primarily western countries. This exit from coal has been largely or even fully accomplished in several countries while the exit from oil and natural gas (the most important fossil energy sources in total energy consumption) that is also essential for climate neutrality is still in its infancy. This step is proving to be far more difficult politically as can be seen in the current debates on the heat transition or the transport transition in the direction of electrical or hydrogen electrolysis-based solutions.

The coal exit is understood primarily – and in particular from the viewpoint of the decisions being implemented in Germany – to mean the phase-out of coal-fired power generation, including the associated coal-based generation of district heating. The target is the decommissioning of all coal-fired power plants still in operation with a national output capacity of around 30 MW (temporarily increased to 38 MW) in the longer term as provided in the Coal Exit Act, i. e., by 2038 (and “ideally by 2030” from the political perspective of the governing coalition). Here in Germany, this simultaneously involves the complete shutdown of domestic coal production, specifically the end of German lignite mining, as the last German hard coal mines were closed in 2018. Lawmakers in Germany have not (yet) addressed the discontinuation of the use of coking coal and coke in the steel industry, certain niche uses in other industrial sectors and on the heating market (although ultimately equally irreconcilable with the zero CO2 target) and currently supplied entirely by imports.

The temporary return to the electricity market of hard coal-fired power plants from the grid reserve and lignite-fired power plants from the security standby service that had already been taken offline or were scheduled for decommissioning in the near future, which for the moment has been limited to a final deadline of 31st March 2024 and affects a total of about 8 GW, is not seen as contradictory to the coal exit. The two 600 MW lignite-fired power plant units Neurath D and E have even received permits to remain online until 31st March 2025 if needed. The hard coal-fired power plants from the grid reserve and the lignite-fired power plants from the security reserve were granted approval pursuant to the Act for Maintaining Supplementary Power Plants with the aim of securing the availability of electricity despite the crisis in natural gas supplies of 2022 resulting especially from Russia’s war of aggression against Ukraine. It should also be noted that the last three German nuclear power plants were shut down at the same time; although their operation had been extended until 15th April 2023, they have now been finally decommissioned owing to political and legal considerations. The question as to whether the changes in the geopolitical circumstances on energy markets after the “turn of the times” should not also lead to different energy policy conclusions for coal-fired power generation is hotly debated, at least among experts, in view of the need to avert a possible energy crisis. (1) The discussion would be even more pertinent, as well as being highly relevant for the comparison with the alternative of wind power discussed in detail below, if the option of linking coal-fired power plants with CCS technology (CCS: Carbon Capture and Storage), i. e., the capture of CO2 from the exhaust gases and its permanent geological storage and neutralisation, were given due consideration. These measures would open the door to climate-neutral coal-fired power generation that could even serve as a benchmark for the economic and ecological measurement of renewable alternatives such as wind energy within the framework of a scientific and evidence-based energy policy. (2) The Intergovernmental Panel on Climate Change and the majority of climate scientists or the International Energy Agency (IEA) have been advocating the global deployment of CCS technology for years, as has the EU Commission. (3)

A large number of countries, including the USA, China and (particularly in Europe) the UK, Norway and Iceland, have long been pursuing commercial CCS projects across a broad technological spectrum; estimates indicate that, under favourable conditions, costs would amount to 60 to 80 €/t of CO2, a figure below the current CO2 prices in EU emissions trading, which are expected to continue their upward trend. (4) In the meantime, the Federal Ministry for Economic Affairs and Climate Action (BMWK) and the German government are also examining a possible reform of the German Climate Protection Act that would, among other things, give a role in achieving national climate neutrality to the direct capture of CO2 from the air (DACCS: direct air CCS) that is relevant for both various fossil industrial processes and power plants and, what is more, would allow the storage of CO2 under German soil, including the seabed. (5) However, there has been no talk at either the German or European level of halting or at least temporarily suspending the coal exit by transitioning to CCS power plants. From an objective perspective, this is puzzling. However, should coal-fired power plants (be forced to) contribute to securing the availability of electricity for a significantly longer period than foreseen at this moment, there is really no way around this option in view of the climate targets. The sequestration of CO2 could also be combined with its (partial) utilisation in the form of CCU technologies (CCU: carbon capture and utilisation). In this case, it becomes available as a source of carbon for a number of chemical and biotechnological processes, e. g., for the production of certain plastics, building materials or synthetic fuels. Using CCU in combination with hydrogen technology would realise even more extensive application opportunities. In other words, CCU technologies would harbour considerable potential for climate protection.

Meanwhile, energy policies continue to prioritise the massive expansion of new renewable energies, especially wind power, as the ultimate path to climate-neutral electricity generation. Renewable energy projects, with especially strong emphasis on wind turbines, are also viewed and recommended as inescapable alternatives fuelling the regional transition of energy and economic activities at coal sites after the closure of coal-fired power plants and coal mines. (6) These attitudes foster the visions behind, i. e. the district plans for the coal exit already being implemented in German lignite regions, mostly in conjunction with broader energy park projects involving wind farms, as well as for international and European projects. Similarly, a number of wind turbines have now been installed on the waste dumps left behind at the sites in the Ruhr and Saar coalfields after the complete shutdown of German mining operations, and even more new wind turbines are being planned or are under consideration. (7)

An unbiased, scientific analysis seeking to determine what conclusions have been drawn as of this time and what prospects and problems relating to wind turbines arise specifically for the transition of coal sites are the subject of this paper. The authors draw on their own findings and insights gained from participation in two research projects funded by the EU and the European Research Fund for Coal and Steel (RFCS) entitled POTENTIALS and GreenJOBS, respectively. (8)

Enormous political prospects for wind power in general

The deployment of wind power facilities has progressed rapidly both in Germany and worldwide. According to information from the International Renewable Agency (IRENA), global wind power capacity increased by a factor of 75 to 564 GW between 1997 and 2018. According to figures from the Global Wind Energy Council (GWEC), a cumulative global total capacity of 837 GW had been reached in 2021, a further growth spurt of 48 % in three years. (9)

In the EU, an early pioneer of wind power internationally thanks in particular to activities in Central and Northern Europe, wind power capacity in 2022 amounted to approximately 204 GW, more than ten times the figure of 2001; about 16 GW of this figure was offshore capacity and 188 GW was onshore wind power (Figure 1).

Fig. 1. Evolution of wind power capacity in the EU 2001 to 2021 (onshore). // Bild 1. Entwicklung der Windenergiekapazität in der EU 2001 bis 2021 (onshore). Source/Quelle: Eurostat

Germany’s share of a good third of EU capacity – just under 66 GW, 8 GW of it offshore and 58 GW onshore – make it far and away the “European champion” in wind power, leading Spain (31 GW), France (21 GW), Sweden (15 GW) and Italy (12 GW) by a wide margin. (10) However, the clear “wind world champion” is currently China and its 328 GW of wind power capacity (2021). Roughly speaking, this is one and a half times the EU capacity, two and a half times the wind power capacity of the USA (133 GW) and five times the wind power capacity of Germany – a population that is about 17 times smaller and a land area that is 27 times smaller than that of China mean, however, that Germany has even today a significantly higher density of wind power turbines. (11)

Germany and the EU are planning an accelerated expansion of wind power for the future. In 2022, there were 28,380 onshore wind turbines with a capacity of 58 GW and generating approximately 103 TWh of electricity in Germany. (12) Total wind power contributed 21.7 % to domestic electricity generation in 2022 and had become the Number 1 energy source of the country, just ahead of lignite (20.1 %). Total renewables (plus photovoltaics, biomass power generation, hydropower and other renewables) accounted on average for 46.2 % of the electricity generated in 2022. In comparison, coal as a whole (lignite and hard coal) reached 31.3 %. However, these ratios are put into perspective when the total primary energy consumption (PEC), which is about five times as high as electricity consumption, is considered. The share of renewable energies in PEC was only 17 % in 2022, and the share of wind power specifically was 3.8 % (wind and solar together 6 %). (13)

The Renewable Energy Sources Act (EEG) sets targets for the share of renewable energies in power generation in Germany at 80 % by 2030 and 100 % by 2045. On this journey, onshore wind power is scheduled to expand to 115 GW by 2030, i. e., more than twice as much as in 2021, and 30 GW from offshore facilities is planned by then (almost four times as much); 2035 targets have been set at 157 GW onshore and 40 GW offshore. In 2040, onshore wind power is supposed to have expanded to 160 MW (three times today’s level) while offshore capacity is supposed to increase to 70 GW by 2045. Achieving the onshore targets alone by 2030 would require the construction of “as many as five wind turbines every day” (German Chancellor Scholz at the Hanover Fair on 16 April 2023), i. e., more than around 1,500 new wind turbines or a good 7 GW annually or 12,250 additional wind turbines of the 4 MW class in total. In comparison: 551 onshore wind turbines with a capacity of 2.1 GW (the target was 3 GW) were built in 2022. The entry into force of the Wind Energy on Land Act on 1 February 2023 also provided that 2 % of Germany’s total land area would be designated as priority areas for wind farms beginning in 2030. Every site suitable for wind power is subject to consideration for this purpose, the applicable planning law will be considerably simplified and accelerated, and even nature conservation and biodiversity concerns are supposed to take a back seat or possibly be compensated solely financially because the expansion of wind power is declared to be a “priority public interest”. The priority feed-in to the power grid remains unchanged, and the state-financed guaranteed rates for onshore wind power will increase substantially once again from 5.88 to 7.35 eurocents/kWh as of 2023.

Measured against the benchmark of these political objectives, the prospects for wind power in Germany – viewed in isolation and without weighing the side effects and consequences in the overall context – are more than favourable. There are similar deliberations at the EU level and in many of its member states; in the course of the European Green Deal and the “Repower Europe” programme launched in 2022 in response to the Ukraine war, 31 GW of wind power are supposed to be added across the EU every year from 2023. In this sense, former coal sites will undoubtedly be able to make a certain contribution and benefit from wind power themselves, whether because of open spaces created on high-wind plains or on higher-lying waste dumps left after the closure of coal mining activities. Just how meaningful this contribution will be, what opportunities might arise from it and what risks and restrictions will have to be taken into account are scheduled for more detailed assessment beforehand.

Technological and commercial development of wind power

Fig. 2. Wind power technology from the first to the fourth generation. // Bild 2. Windkrafttechnologie von der ersten zur vierten Generation. Source/Quelle: Kaldellis/Zafirakis 2012

The technological development of wind power is without doubt very impressive. There is now talk of the “fourth generation” of wind power technology (Figure 2), which originated in the ancient world of the Middle East with the invention of wind-powered grain and water mills with a vertical axis. The first wind turbine for electricity generation on a larger scale was constructed in Cleveland, Ohio/USA, in 1888, a 12-kW turbine on a sturdy support structure (although still made partly of wood) and operating at low speed. Today, there are high-tech turbines on towers with nacelles at heights of more than 200 m, packed to the brim with electronic devices, including control and communication systems, automatic wind measurement and speed regulation, and with horizontal axes and always three aerodynamic rotor blades of 70 m and more in length and manufactured using glass and carbon fibres, highly stable epoxy resins and other materials. (14) The most modern onshore wind turbines have a nominal output of 5 MW while offshore turbines are even larger and now reach an output capacity of as much as 15 MW. In the meantime, wind power technology has been assigned a maturity level of “nine” on the scientifically established, ten-stage Technology Readiness Level (TRL).

In terms of physics, wind energy is the kinetic energy of air movements that results from the air mass A and the air velocity v. The air mass itself is the product of air volume V and air density ρ. The wind power PWind is calculated using the equation PWind = ½ ρ A v3. In other words, wind power is proportionate to the cube of the wind speed, i. e., a doubling of the wind speed triples the wind power and, conversely, a halving of the air speed results in only a third of the wind power. The primary factors for the performance of wind turbines are therefore the wind speed, which is usually greater at higher altitudes than near the ground, and the length of the rotor blades used to “catch” the wind, both modified by topographical and technical conditions. This explains why wind power technology is moving towards higher towers and longer rotors.

“Windy” locations are always favourable for the productivity of wind turbines. The turbines of a wind farm, i. e., a group of wind turbines concentrated within a certain area, should always be placed at a distance from one another of eight times the rotor diameter in the main wind direction and at least four times in the secondary direction so that the disruption of the air flow to other turbines is minimised. However, it must not be too windy, either. During severe storms, wind turbines must be shut down for technical safety reasons because of a possible overload. Wind conditions on land are optimal at wind speeds of 12 to 16 m/s. The declared nominal outputs, e. g., 4 MW, are always shown in reference to these optimal conditions. The effective wind power is usually less than the potential. Aerodynamic energy losses at the rotor, mechanical losses in the gearbox and electromechanical losses at the generator lead to a maximum degree of efficiency (generation efficiency) of wind turbines of typically 30 to 40 %.

Owing to the natural weather-related volatility of wind movements, onshore wind turbines generally achieve utilisation rates, measured by the so-called capacity factor, of no more than between 25 and 40 % even in favourable locations and usually less on average during regular operation. More than 40 % is possible for offshore facilities. (15)

In consideration of low-wind periods and even phases of calm, the “secured output” or “output credit” of onshore wind turbines at any time is still estimated at no more than 1 %. As the feed-in of solar power fluctuates strongly as well, a combined lull in these two sources can lead to the phenomenon of the so-called dark doldrums. A 2018 study by the German Weather Service (DWD), e. g., determined no fewer than 23 lulls lasting 48 hours or longer in 2017. Even longer periods of lulls over several days or weeks are possible. (16)

This volatility of wind power requires the combination of wind power with electricity storage, conventional backup power generation and/or electricity imports, most of which will be generated using conventional technologies when the wind is weak across Europe, to ensure round-the-clock availability of electric power. Alternatively, the only defence against grid collapses is “demand management” in the form of quantitative or temporal shifting of electricity demand that may even reach the stage of direct load shedding. Mature electricity storage systems exist today solely in the form of batteries with reserves for mere seconds or minutes and as pumped-storage facilities with reserves of a few hours – available solely to a limited extent in Germany because of the natural conditions. Since the capacities for renewable base-load electricity from sources such as hydropower, geothermal energy and biomass/biogas are also relatively limited by the natural conditions in this country and in many others, domestic or possibly foreign conventional power plants (fired using natural gas, oil, coal or nuclear) will remain absolutely essential as balancing and reserve capacities until sufficient long-term electricity storage facilities such as those planned for green hydrogen-based electrolysis gas have been developed and made available; their realisation is currently still a dream of the future, however. All in all, volatile wind power, regardless of its location, can contribute to a sufficiently secure power supply solely as a limited component of a general power generation system.

Comparisons of the costs of wind power with conventional power generation must consequently always take these system costs into account, no matter how impressive the cost degression that has been achieved in the wind power sector through technological progress, economies of scale and substantially heightened competition along the entire added-value chain. The most recent report of the International Renewable Agency (IRENA) on the Renewables Power Generation Costs 2021 charts the cost development for wind power since 2010 as shown in table 1, once in terms of the total installation costs per kilowatt and once in terms of the costs of electricity generation as so-called levelised costs of electricity (LCOE) per kilowatt hour. The worldwide cumulative capacity of onshore wind power included in the report rose from 178 to 796 MW (by 423 %). (17) However, the aforementioned system costs are not included in the figures.

Table 1. Global (seighted) costs of wind power. // Tabelle 1. Globale (gewichtete) Kosten der Windkraft. Source/Qulle: IRENA 2022

The electricity generation costs for onshore wind power in 2021 calculated by IRENA can be restated as 0.28 eurocents/kWh, i. e., wind power can now be produced at just under 3 eurocents/kWh. The assumption here, however, is of state-of-the-art turbines with a maximum achievable capacity factor onshore of 39 %, which is likely to apply to very few existing wind farms. As previously mentioned, system costs for backup provisions have not been included in these calculations. According to IRENA, 64 to 84 % of the installation costs arise from the manufacturing and procurement costs for the turbine itself. In addition, there are the costs for the grid connection (as much as 14 %), the costs for construction and other capital costs (the latter two amounting to approximately as much as 10 % each). Moreover, so-called O&M costs (operation and maintenance) of 2 to 3 % of the installation costs are incurred annually during operation. Due to the considerable increase in energy and material costs from the general inflationary jump in 2022 that has not spared the production of wind turbines and their infrastructure, the cost statements for 2021 are no longer entirely representative and require adjustment to secure valid comparability with today’s figures. Nonetheless, further cost degressions from economies of scale and experience and various optimisations can probably be expected in the future. Under highly favourable conditions, onshore generation of wind power at a good 3 eurocents/kWh will be possible even in Germany. This is, however, a best value that cannot be achieved as an average for existing facilities. Other estimates based on the “real costs” of 3 MW onshore wind turbines with an average availability of 20 % – still the prevailing norm at many sites in Germany at present – put the figure at 6 to 7 eurocents/kWh, plus demolition and dismantling expenses of around 7 to 8 eurocents/kWh. (18)

The full costs of electricity generation for all types of production include components of fixed or capital costs (CAPEX values) that are incurred almost exclusively for wind power and variable costs of operation (OPEX values). The complete life cycle from “greenfield” to power plant or facility and back to greenfield includes the elements of land acquisition or lease, raw materials, construction, maintenance, labour costs, insurance, fuels. They are almost completely irrelevant during wind power in operation unless external power sources such as diesel generators must be used for restarts after failures – possibly repowering, dismantling and disposal. As previously described, however, this does not include the system costs, which are particularly significant for a weather-dependent producer such as wind or solar power, but which wind power has not yet been required to bear within the German electricity generation system. Realistic cost comparisons with conventional power generation must take these system costs into account. Equally, the CO2 prices incurred from the European CO2 emissions trading system, the EU ETS, or the costs of CO2 avoidance from the installation of CCS or CCU technologies must be attributed to conventional electricity generation.

The system costs of volatile wind power include, besides the backup provided by other manageable power plant and/or storage capacities, the costs of grid integration and expansion and control energy; while these elements generally apply to all types of power generation, they already exist as services for conventional power generation. Furthermore, there are as special features the costs of overproduction of wind power, which may result in shutdowns or paid exports and compensation of producers even without any purchases of power; the costs of necessary short-term capacity adjustment in the power plant park in the event of weak wind or other capacity restrictions (so-called redispatch); further costs for maintaining flexibility such as those incurred from increased wear of fossil power plants resulting from the load sequence of the steep power ramps for wind power; and even the costs of the reduction in full-load hours of conventional power plants because these must be available, but are used less as a consequence of the expansion and feed-in priority of renewable energies. A model for German electricity producers estimates these system costs for wind power, based on the system share of more than 20 % that has now been reached, at close to 5 eurocents/kWh. (19) As previously stated, this is a macroeconomic, not a microeconomic calculation.

However, the decisive economic factors for wind power itself are, and will remain, the wind conditions at any given time and the wind yield that can be achieved at any given location as well as the electricity price remunerating the wind power at any given time and not the installed capacity and its infrastructure. Under favourable conditions, single turbines and even entire wind farms can be operated profitably, even highly lucratively, in the long term. It is also clear that persistently high electricity prices can give wind power a further boost in general, but from the point of view of electricity consumers and the national economy as a whole, they must be assessed differently. All of these deliberations are also valid for the transition of any coal sites.

In terms of energy economics, it is abundantly clear that single wind turbines or the small groups of them that can be placed on narrowly restricted areas or on waste dumps – in the Ruhr Valley, e. g., a maximum of four turbines with ± 3 MW output are located at this time on one waste dump site (20) – but even larger onshore wind farms with 20 or more wind turbines and planned capacities of 100 or even 200 MW nominal output (21) cannot come even close to the electricity generation capacity that large coal-fired power plants with up to 1,000 MW and over 80 % secured output previously represented at these sites. At any specific location, wind turbines as an energy location can obviously replace no more than a fraction of the performance of a former coal site.

The decentralised energy production in the large number of wind farms distributed over the entire country and offshore in the sea is what makes wind power macroeconomically viable. This means, however, high (and in comparison with coal-fired power, more extensive) utilisation of land and materials, leading logically enough, all other things being equal, to increased land and raw material prices.

From an energy management perspective, wind power on former coal sites always makes even more sense if it is developed in combination with other sources of potential energy business such as those proposed in the research project POTENTIALS funded by the EU and RFCS and featuring the favoured business model of an “eco-industrial” park. The POTENTIALS studies examined sites with a combination of decommissioned coal mines and coal-fired power plants and neighbouring industry seeking the best possible exploitation of synergies for “green” energy production and supply in the sense of the European Green Deal. A further assumption was the continued utilisation of the previously used areas, their infrastructure and the installed networks. The eco-industrial park on one such former coal site comprises a “virtual power plant” of interconnected wind power and photovoltaic (PV) plants on the site’s waste dumps in combination with an unconventional underground pumped-storage power plant and mine water for geothermal purposes from the former mine and the use of battery technologies or even the thermochemical use of molten salt as storage options in the former power plant infrastructure. Depending on the requirements and opportunities of the neighbouring industries, the park could also be expanded to include hydrogen production (green hydrogen plant) and possibly the production or use of biofuels. Other technologies have also been considered. (22)

Employment potential of wind power at former coal sites

The employment potential of wind power operations at former coal sites is limited in much the same way as the energy industry potential; it is significantly lower for any given site than the typically more than 100 or 200 jobs in a former coal-fired power plant or the 1,000 or more employees in former coal mines. The employment potential of wind power is considerably greater for the total number of all sites that come into question.

In 2020, the Joint Research Center (JRC) of the EU Commission presented a large-scale study on the employment potential of various green energy technologies (clean energies) in the EU. It also estimated the employment potential of wind power in the regions of European opencast pit coal mines (wind power on coal waste dumps, on the other hand, was not covered by the JRC) and identified a potential of about 100,000 jobs for the EU as a whole. This is an estimate of potential employment and is far from having become reality. According to the JRC, the new jobs created by wind power and additional jobs created by other green energies will be offset by the loss, directly and indirectly, of as many as 340,000 jobs in the EU coal sector by 2050. (23)

The employment potential of wind power in Germany can be more tangibly determined using the pertinent data of the National Specialist Agency for Onshore Wind Power, which most recently published a detailed estimate of jobs related to wind power (in full-time equivalents) along the full length of the added-value chain for the year 2019. (24) In the following, specific reference is made to the state data for North Rhine-Westphalia because they are most representative for wind farms located on waste dumps. They show that a total of about 16,000 jobs were created by onshore wind power in North Rhine-Westphalia; when set in ratio to 6,174 MW of wind power capacity in North Rhine-Westphalia, the figure corresponds to approximately 2.6 jobs (full-time equivalent) per megawatt of nominal output. Arithmetically, a 3 MW plant would therefore have created just under eight jobs. This calculation considers the entire added-value chain, however, from planning to scrapping or recycling of the equipment. Solely the jobs in O&M can be attributed to ongoing operations, and they account for no more than 12.1 % of total employment. That would be about one-third of a job per megawatt or one job per 3 MW facility. It is obvious that this arithmetical position is distributed proportionally among the jobs of different teams, e. g., maintenance technicians, operators at the network operator and commercial employees in the administration. A typical waste dump site with, e. g., three wind turbines would create approximately three permanent jobs while a completely new wind farm with, e. g., 20 turbines of 5 MW each could create approximately 30 permanent jobs.

Far and away the greatest impact on employment – 41.4 % based on the data used here – comes from the manufacture of the turbines. The other calculated employment shares are 5.7 % for research and development, 14.3 % for project development, 1.8 % for financing, 2.6 % for transport and installation, 3.2 % for grid connection, 0.7 % for dismantling or repowering and 18.6 % for other services. The majority of the job effects mentioned are obviously one-off effects due to the manufacture of new or replacement wind turbines. The need for further production ends when and for as long as the installations are in place and continue to operate. Once the expansion of planned or realisable wind power capacities has been completed, a substantial part of the employment effect achieved across the entire added-value chain will simply vanish. In other words, an employment boom will occur solely during the investment and, in part, disinvestment phases, but not during the operating phase of wind power. Massive employment in the wind power sector will be seen solely when considered as the general function of a steady expansion of capacities across all sites and regions.

Furthermore, it must not be forgotten that these are gross effects that must be contrasted against the jobs lost because of the replacement of other types of energy production – in this specific instance, primarily coal-fired power. Similarly, jobs are eliminated in other sectors of the economy because of the so-called budget effect, what is essentially the subsidisation of wind power pursuant to the EEG – previously in the form of the EEG levy, now appropriated from tax revenues – deprives power consumers in Germany of income that would have otherwise been available for other types of expenditures.

It should also be noted that the calculated employment growth other than in ongoing operation and site-related services such as transport and assembly, grid connection, dismantling, etc. will not inevitably be generated in Germany. This is especially true of turbine production. Seven of the world’s ten largest wind turbine manufacturers are now located in China, and they are expanding their international operations at an accelerating pace. Many established European turbine manufacturers, German enterprises in particular, have been confronted with considerable competitive pressure in recent years owing to increased material and energy costs in combination with other location problems such as the complex bureaucratic and tedious award and approval procedures; the consequence, according to media headlines, is a “crisis in the wind power industry”.

One current example is the shutdown of production of onshore wind power gearboxes by the Eickhoff Group at its plant employing 177 people in Klipphausen, Saxony, announced for the end of 2023. The announcement gave “the cost crisis in the wind industry and the lack of stability of general conditions” as the reasons for the discontinuation of production. Eickhoff, headquartered in Bochum/Germany, has its roots in the German coal mining industry and is doing internationally as a mining supplier, but it has also been investing heavily in the wind industry and its equipment for almost 30 years. From now on, Eickhoff wants to concentrate solely on the service business (special gearboxes, prototypes, etc.) in the wind division. (25) Previous examples of a similar nature were seen at Nordex in Rostock in 2022 or at Vestas Deutschland in Lauchhammer in 2021. Siemens Energy delisted its wind turbine subsidiary Siemens Gamesa, jointly operated with Iberdrola, in spring 2023 because of “renewed high losses (884 M € in the first quarter)” and merged it with Siemens Gamesa Renewables Energy for consolidation with its other renewables division. In the previous year, the company had announced the reduction by 2,900 jobs of Siemens Gamesa’s worldwide workforce of 27,000. In addition to unexpectedly high warranty and maintenance costs, which indicate certain quality problems, this was mainly a consequence of strong price competition from Chinese suppliers. (26) The latter are also capturing increasingly large market shares in Europe and consequently added value and employment in wind turbine manufacturing.

Geographical and geotechnical restrictions on wind power

It is astonishing to see how little the public debate on wind power focuses on geographical factors, although they in fact play a decisive role. First of all, there is the north-south gradient in wind speeds that is typical for Germany, speaking more generally, the energy yield of wind turbines is determined to a huge degree by the geographical location in the country and on the European continent (Figure 3).

Fig. 3. UBA map of power plants and wind capacity in Germany. // Bild 3. UBA-Karte Kraftwerke und Windleistung in Deutschland. Source/Quelle: UBA

Wind speeds in the northern coastal regions on the North Sea and Baltic Sea are significantly higher than in southern Germany, resulting in a substantially higher number of full-load hours and energy yields. The Federal Network Agency (BNetzA) consequently shows regional variances in full-load hours and capacity factors (effectiveness in relation to nominal output) (Table 2).

Table 2. Distribution of full-load hours and capacity factors in Germany. // Tabelle 2. Verteilung von Volllaststunden und Kapazitätsfaktoren in Deutschland. Source/Quelle: BNetzA

Recent calculations by Tabbert for the years 2018 to 2021 (27), however, indicate that the BNetzA figures for onshore plants are inflated because they statistically include offshore output that displays considerable differences even within the various regions. Starting from other public data, Tabbert arrives at effective full-load hours and capacity factors for onshore wind turbines of only 1,750 h (20 %) for the north, 1,690 h (19 %) for the central regions and 1,650 h (18 %) for the south. (28)

It is clear that topography also plays a major role for specific locations. Wind speeds on windswept plains or at higher altitudes such as on hills, mountain peaks or waste dumps are considerably higher than in heavily rugged or built-up areas or, e. g., behind the ridges of the central highlands or on the lee side of other wind farms. A height difference of no more than 100 m can mean wind speed that is seven km/h faster. In very unfavourable wind locations in southern Germany, on the other hand, it may be possible to achieve a capacity factor of no more than 5 %, which explains why the expansion of wind power has been so slow and sluggish there. And there are general questions about the sense of the goal of nationwide expansion of wind power in Germany rather than more differentiated approaches.

The German lignite and hard coal mining areas are all located in the central wind region. Former coal sites with adjacent open spaces and waste dumps offer particularly favourable wind sites in this region. Based on practical experience, the reference yield is estimated to be 15 to 20 % higher than in the flatlands, especially on the waste dumps of the hard coal mines (Figure 4), which is why the above-mentioned BNetzA data seem to be the most representative for them.

Fig. 4. Wind turbine on the Brinkfortsheide waste dump in the Ruhr Valley district. // Bild 4. Windrad auf der Halde Brinkfortsheide im Ruhrrevier. Photo/Foto: RAG Montan Immobilien/Thomas Stachelhaus

From an economic point of view, the question of the “social optimum” with regard to the siting of wind turbines always arises, and the geographical factors of “location” and “distance” also play an important role. In 2021, the Leipzig-based environmental economists Lehmann, Reutter and Tafarte presented a model (29) that determines the economically optimal choice of location for onshore wind power plants in Germany based on the trade-off between the most favourable possible generation costs of wind power, for which the wind speeds at the location are of material significance, and local disamenities for area residents – noise emissions, light reflections and “disco effects”, landscape impairments, etc. The disamenities were mapped as a hyperbolic cost function based on various empirical cost estimates on the topic, starting from the highest costs at a minimum distance of 800 m from the wind turbines to zero at distances greater than 4,000 m. All these calculations were supported with Germany-wide GIS data. The social disamenities quantified in this way prove to be spatially more heterogeneous than the generation costs, but nevertheless display a moderately positive correlation with them. The results also prove to be solid in terms of the magnitude and progression of the social cost function and can be influenced by the minimum distances from local residents or compensation payments. The ultimate conclusion is that “socially optimal” in this sense is the concentration of wind turbines first and foremost in the coastal regions of northern and eastern Germany that are less densely populated. This includes the lignite mining areas in central and eastern Germany, but not the lignite and hard coal mining areas in western Germany, particularly because of the higher population density and the related closer spacing in many cases. The authors acknowledge that their model is merely a fairly rough approximation, that conditions in specific locations may differ and that further research on acceptance issues and the energy system as a whole, including the interconnection with other energy technologies and the grid infrastructure, is desirable.

Viewed in this setting, the fact that former coal sites in western Germany had previously been used as energy sites, mitigating the potential for conflict with local residents, and the degree of acceptance is generally higher than for the construction of new plants on areas not previously used for energy or industrial purposes (not to mention the opposition to construction in a cultural or natural landscape) are arguments in favour of former coal sites, especially as this can be associated with an economic upgrading of brownfield sites insofar as no other possible uses come into question.

Another significant geographical factor for wind power is the considerable area of land it occupies in comparison with conventional energies – compared to a coal-fired power plant with the same generation capacity (without secured output), it differs by a factor of 1,780 (assumption: 1,000 MW coal-fired power plant on an area of approximately 0.5 km2 with 80 % capacity utilisation compared to the required installation of 1,000 wind turbines of 4 MW nominal output each and an average of 20 % capacity utilisation, see area calculation below). Figuratively speaking, an area equivalent to that of almost 1,800 football stadiums rather than that of only one stadium is needed. This enormous additional land use is indispensable, however, if the overall electricity generation contribution expected from wind power and its potential to provide jobs by requiring a large number of turbines are to be realised.

As of today, only about 0.8 % of Germany’s total land area is in use for wind energy. The reservation of a total of 2 % is envisioned in the planning for further expansion by 2030. In 2022, the Competence Centre for Nature Conservation and Energy Transition (KNE), which was established by the federal government in 2013, published the following explanatory information summarising the pertinent aspects of land use by wind power in a succinct and instructive manner (30): “Two percent of Germany’s land area corresponds to an area of approximately 715,000 ha. This is significantly less than Germany’s settlement and transport areas, which account for … 14 % or over 5 M ha. Moreover, the 2 % initially covers solely the area parameters in which wind turbines are to be located, not the area they actually occupy. How many wind turbines can be realised on an area of 715,000 ha fundamentally depends on how “dense” the placement of the turbines can be. On the one hand, they must be constructed at a certain distance from one another to minimise turbulence that would result in increased material stress and higher wear of “downwind” installations. Requirements for stability specified according to manufacturer and type of turbine must also be taken into account. On the other hand, the distances of separation must be chosen to minimise shadowing effects and mutual “wind theft” that lead to decreased efficiency and consequent yield losses … Based on the average wind turbines with 133 m rotor diameter and 4 MW output commissioned in 2021 … an idealised model arrangement of one wind turbine in the centre and four wind turbines at right angles separated by rule-of-thumb distances from one another would result in a nominal output of about 20 MW on an area of 83 ha – 16.5 ha per turbine. Based on the 1.2 % of the country’s area – i. e., about 430,000 ha – which is yet to be allocated, it would theoretically be possible to install capacities of around 100 GW … However, it must be taken into account that the actual total area designated for wind energy consists of a large number of separate areas of different sizes and not a single contiguous area. Moreover, the real landscape never matches the ideal model, which is why there are always additional limiting factors that have an influence on the number of turbines and the realisable output …”.

The KNE also emphasises (31): “Depending on the region and prevailing wind speeds, the topography and the “roughness” of the landscape relating to vegetation structures, different types of turbines with different generator outputs, rotor diameters and tower heights are used. Technological development is moving towards the use of larger rotors and higher outputs. In addition to the rotor diameter and the separation between the turbines they require, the size of the area, the exact layout of the area and the position of the area in the spatial setting – namely, to the prevailing wind direction – influence the number and output of the turbines that can be erected in the area … The specific project site must also be developed by the installation of road and cable infrastructures. The associated “land access” must be guaranteed by the conclusion of contracts with the land owners. Regulation of the distance to residential buildings …, building height restrictions or emission and monument protection requirements may also prevent the full use of allocated areas. Conflicts with biodiversity protection regulations may also prohibit the realisation of wind turbine facilities on some areas. In other words, how land areas can actually be utilised is highly dependent on the specific case and is influenced by a large number of variables, some of which become relevant only at the approval level. The real development potential is therefore lower than the figure calculated above. This is also in line with the conclusions of research … The usability of areas secured for wind energy during planning procedures can be increased both at the planning level and at the approval level – by reducing the minimum distances from residential areas in effect nationwide and reducing distances from military and civil aviation safety facilities. Further potential could be tapped if the rotors were always allowed to project beyond the boundaries of the designated areas and only the foundations or towers had to be located within the areas. Regulations for the protection of biodiversity that can have a positive effect on the usability of areas secured during planning procedures are also possible.”

Finally, the KNE comments on the issue of soil sealing (32): “The use of wind energy on a site should by no means be equated with a complete consumption or even loss of land. Unlike the designation of new settlement and transport areas, which are largely sealed after realisation, or opencast pit mines, which also entail long-term, complete land use, the use by wind turbines is of a different nature. (Authors’ note: Although the KNE statement is accurate, it does not mention that very extensive renaturation is possible and is also taking place in Germany for decommissioned opencast pit mines and even disused waste dumps.) A base area of approximately 100 m2 is visible as part of the foundation on which the tower stands or is mounted for the wind turbines currently in general use. Depending on the type of turbine and manufacturer, the total foundation area involving permanent impairment of soil functions encompasses 350 to 600 m2. The area of the foundation extending beyond the base is largely covered again with topsoil or gravel during the operational phase. The crane footprint for the construction of the turbine and for any repairs, which is also generally gravelled, remains permanently partially sealed. It accounts for an average of about 0.15 ha per turbine while the access road requires on average an additional 0.25 ha. Wherever possible, previously existing roads and paths that need only be widened slightly are used. All in all, a total of less than half a hectare of fully and partially sealed area can be assumed per turbine. In relation to the space requirement of 16.5 ha per turbine calculated above, the permanent land use accounts for only 3 %. The remaining 97 %, including the assembly and storage areas required during the construction phase (another approximately 0.4 ha per turbine), remains unsealed during the operational phase. If the additional wind energy capacity of 70 GW targeted for realisation by 2030 and the current average turbine capacity are taken as a basis, 17,500 new turbines with a (partially) sealed area of around 8,000 ha will be required. Of the 1.2 % of Germany’s land area (just under 430,000 ha) that must still be allocated to achieve the 2 % target, only 2 % would be (partially) sealed land – 98 % of the land required for the construction of wind turbines would remain available without restriction for mainly agricultural and forestry use.”

The KNE makes it very clear in these comments that, in addition to the need for additional areas for the expansion of wind power, which is undoubtedly enormous even from a relative perspective, the degree of suitability varies from one site to the next and that a large number of geographical factors and restrictions alone that demand a differentiated assessment of the expansion potential must be taken into account. Apart from the wind conditions already mentioned, it appears that former coal sites are likely to be particularly suitable, especially because road, path, and power line infrastructures are already in place, there is additional potential for exploitation by the energy sector, and the access to the areas is already available. Wind projects previously realized on coal sites have long since also proven their compatibility with agricultural and forestry use.

From an economic point of view, however, it should be noted that the KNE did not address possible competing uses of open spaces for other economic purposes such as housing, transport projects, commercial projects, or leisure and tourism interests with the possible associated conflicts of political objectives and the increase in land prices to be expected as a consequence of the limits imposed by the overall fixed amount of available areas – whether for wind power or other uses. The KNE does not mention at all the additional areas necessary for the related infrastructure expansion that is required for distribution grids, batteries, or storage media such as hydrogen and the new transport pipelines that will be needed (or until that time: conventional backup power plants).

From an ecological point of view, the KNE – ironically – merely hints at the conflicts with nature conservation or the interests of landscape protection for residential residents that might well be expected and refers to them solely in terms of the expansion potential. It is also astonishing that the KNE does not say a word about recent research on the problems of wind power development for the microclimate of the sites and the regional wind and weather conditions. For instance, an ecologically significant drought effect on the sites of wind turbines caused by the on-site air turbulence that can impair the previous natural temperature and moisture balance and lead to the affected soils drying out has been proven. Moreover, a reduction in precipitation has been observed in the lee of wind farms. The technical term “terrestrial stilling” – or, according to the DWD, “global terrestrial wind calming” – has also been used to describe the phenomenon of decreasing wind speeds over the northern hemisphere that has been observed for around 20 years. It describes a decline in natural kinetic energy and displays a striking correlation with the expansion of wind power in certain regions over this period. It has been known for an even longer time that wind turbines located kilometres apart from one another can cause mutual wind shadowing from energy extraction and wake vortices, an effect that may be exacerbated by wide-area expansion. More research on this subject appears to be needed, and researchers from China in particular have called on governments around the world to give serious consideration to this issue. In any case, there appears to be a possibility, in addition to microclimatic effects of wind turbines that will increase in importance parallel to the land use for the sites, of “large-scale atmospheric disturbances at high altitudes, perhaps even impacting jet streams and related weather patterns and leading to prolonged aridity, regional droughts or heavy rainfall events caused by rain areas that do not move away”. (33) It would be fatal if the climate protection expected from the expansion of wind power were to have the opposite effect – at least in part.

It is remarkable that although the KNE addresses the significant regional differences in wind conditions, it does not draw any related conclusions about a regionally more differentiated breakdown of the 2 % target. From an economic point of view, the concentration on coastal locations, high altitudes, and open spaces that are well suited for energy production would seem to be more reasonable, while in Germany, the classic economic law of diminishing marginal returns holds true with respect to the achievable wind power output as one moves further inland and towards the southern part of the country, and the use of wind energy begins to appear much less rewarding economically. But the KNE ignores or treats as “blind spots”, so to speak, five other important points about land use.

The issue of land sealing that is addressed as one topic, e. g., is likely to loom larger as the trend towards ever larger and heavier turbines and the additional construction measures they require at the site continues, encompassing the requirements for road transport of the wind turbines as a totality and not only for any given site. Obviously, from a strictly technical point of view, it would often be possible to unseal the areas when the operational life of the turbines comes to an end, but the work would be very time-consuming and expensive; furthermore, previous experience has demonstrated a complete lack of interest in the realisation of such measures, and the unique problem of the unusability of sites strewn with the concrete foundations of previous wind turbines is foreseeable.

Furthermore, the KNE’s comments on area usage, while per se factually correct, are clearly designed to provide argumentative backing for the political expansion target of 2 % and to relate area usage to direct land utilisation. Certainly, agriculture and forestry are usually possible among wind turbines. But the land cannot be used for settlement and transport purposes. When this yardstick is used, the area usage for wind power is significantly greater than the 2 % of the nation’s land area, as is revealed by a simple and rough, but nevertheless plausible, counter-calculation. The political target is the new construction of 102 GW of onshore wind power in Germany by 2040, which would require 25,500 turbines of the 4 MW class in addition to the almost 29,000 existing turbines for which repowering is to be expected in this period; this would in itself require the modification of the previous 0.8 %, but this issue will not be considered at this time. As the KNE states, turbines of the 4 MW class typically have a rotor diameter of 133 m. For the above-mentioned technical reasons, the “8-D rule” (eight times the rotor diameter) requires the installation of the turbines at a distance of at least 8 x 133 = 1,064 m from one another for optimisation of performance and the prevention of mutual performance interference; what is more, there must not be any other permanent structural or natural obstacles to wind flow between the turbines. Other distance requirements, especially to residential buildings, and other legal restrictions are neglected here. The same requirements apply from side to side in areas of changeable wind conditions. In effect, a circle with a radius of 532 m can be assumed as the area required for every single wind turbine. The area of the circle is calculated as r2 x π – in this case, 0.532 km x 0.532 km x 3.142 = 0.889 km2. An additional 25,500 wind turbines nationwide would require a total area of 22,670 km2. The Federal Republic of Germany has a total area of 357,588 km2. So the new construction of wind turbines alone would consume almost 6.3 % of the country’s territory; added to the 0.8 % already in use, the required area would be 7.1 %, not 2 % (i. e., a good three and a half times as much) – quite a large difference. (34) Either the area required for the politically envisioned target capacity will be much larger than assumed and claimed or the capacity target will effectively be missed, a more likely scenario because the turbines will be constructed too closely together or their output will be diminished by other strictly factual restrictions.

The KNE also did not include additional land requirements for the energy system as a whole that, as explained above, must be expanded simultaneously with wind power, namely, land for the necessary electricity storage facilities (batteries, pumped-storage facilities, hydrogen plants, etc.) and other renewable electricity generation facilities (solar power, biomass/-gas etc.) and/or conventional backup power plants plus their own distribution infrastructures. Moreover, all of this requires additional material, i. e., additional raw material extraction in Germany or abroad, as will be explained later. Consequently, the factor of area is not only required by the wind turbines themselves.

Finally, the KNE did not take a look at the ground beneath the areas, i. e., it did not shed light on the geotechnical preconditions for the construction of wind turbines and in particular for their stability. And the KNE is not alone in this respect – politicians also seem to have paid little attention to the subsoil of the areas with the planning expansion target of 2 % of the nationwide land area or else the potential problems are considered to be relatively easily resolvable. This is a rather sweeping assumption that overlooks some of the geotechnical difficulties that are possible or relevant in this country.

While the subsurface of coal mining sites is well known, has been tested and (in many cases) examined in greater detail and the backfill material of “landscape structures” such as waste dumps left behind by mining activities is known and documented – at least in Germany – this cannot be assumed to be the case across the board for a large part of the geological subsurface of other onshore wind power sites; in other words, extensive geotechnical investigations are required in advance before definitive site decisions can be made for wind turbines or their exact location, size and design. In any case, typical geological (soil) risks must be avoided through suitable geotechnical measures or the choice of a different location (Figure 5). (35)

Fig. 5. Typical geological risks for wind power projects according to (35). // Bild 5. Typische geologische Risiken für Windkraftprojekte nach (35).

Geotechnical site investigations are indispensable for the exploration of the specific soil properties and possible risks, be it through drilling, pressure soundings, in-situ measurements, e. g., using dilatometers, geophysical surveys, groundwater investigations and various laboratory test methods. For wind turbines, sufficient geotechnical preconditions are important, especially with regard to the stability of the foundations and the stability or fluctuation margins of the towers under changeable wind conditions.

The foundations in particular must fulfil a number of geotechnical functions, including basic stability to withstand weather-related and self-generated sheering and tilting forces, the load-bearing capacity of the soil, minimum stiffness, durability, allowance for some lifting, inclination and settlement movements (deformation capacity) and other structural considerations. The stability is achieved primarily from the massive dead weight in conjunction with the topsoil or the additional filling of the foundations. (36) Gravity-based spread foundations made of (steel-reinforced) concrete are the preferred foundation types for onshore wind turbines. They are often supplemented by deeper pile foundations in softer subsoils, but there are various other support and pillar methods. Until a few years ago, the typical foundations of wind turbines had a width of up to 20 m with a cylindrical base sunk up to 3 m into the ground in the middle for the tower. The dimension of the foundations is often increased for newer larger structures, however. In any case, site-specific solutions must be found for each wind turbine. If the essential geotechnical requirements are disregarded in the design of the structure and the choice of location, the consequences for the stability can be fatal (Figure 6).

Fig. 6. Toppled wind turbine. // Bild 6. Umgestürzte Windturbine. Photos/Fotos: agrarheute.com 2017

In principle, the requirements for former coal sites as locations for wind turbines are no different. In this respect, the geological conditions in Germany have often made a geotechnical case for the use of so-called vibro-stone compaction in which stone “vibro-stone columns” are driven into the ground of the site to increase its load-bearing capacity. One example is found at the Königshovener Höhe wind farm (21 turbines) in a former opencast pit lignite mine that was partly filled with sand and silt, which is why the vibro-stone columns were driven up to 20 m deep and additional measures were carried out to improve soil stability. (37)

This vibro-displacement densification and soil stabilising elements are also used on the waste dumps of the former hard coal mines on which wind turbines have been erected whenever required by the geotechnical conditions. In the case of wind turbines built on waste dumps in particular, a special feature besides the limited space at the top of the waste dump is that they are often placed closer to the slope rather than at the centre for stability reasons, depending on the size, material and the topography of the waste dump itself. Here, too, it becomes clear on both a large and small scale, and especially from the perspective of the transition of coal sites, how much the usability of wind power ultimately depends on various geographical factors.

Environmental and raw material problems of wind power

A differentiated assessment of wind power as an “eco-energy” with regard to environmental and raw material problems is also well advised. There is no doubt that wind power offers huge benefits for climate protection and air pollution control in the regions where it is used. Nevertheless, they are offset by some disadvantages relating to other environmental aspects and the raw material issues.

Various negative environmental aspects have already been addressed (soil sealing, noise/infrasound, microclimatic and possibly even macroclimatic effects). Acute conflicts with efforts for landscape protection, nature conservation and biodiversity are more and more frequently the subject of public debate, as is the impact on both flora, especially clearing of forest areas, and fauna, e. g., harm to populations of birds of prey, bats and flying insects. Much as is true of conventional energy and industrial facilities, there are accident risks involving environmental hazards for wind power plants. Numerous incidents at wind turbines have been documented (torn-off rotor blades, brittle or toppled towers, cracks, fires, oil leakage, failure of the control system, explosion of the battery storage, collisions with small aircraft), partly due to natural causes as storm or thunderstorm damage, partly due to material fatigue, technical failures or human error. (38) The problem of recycling rotor blades, which is still unresolved, has recently been the subject of media attention as a specific contaminated site issue. To be sure, the industry association Wind Europe notes that 80 to 90 % of the components of a wind turbine can be recycled, but there are still no ecologically sound recycling methods for the fibre composites used in rotor blades, which are usually reinforced with carbon and glass fibre bonded with epoxy resins. Shredding is possible only in a very few isolated cases. At present, thermal recycling, i. e., incineration, appears to be the only disposal method acceptable on a large scale in this country, but this is a highly complex procedure and is not entirely residue-free, either. In fact, a significant proportion of the wind turbines and their components decommissioned in Germany have been exported to other countries where worn-out rotor blades are usually buried in landfills, and defective wind turbines are sometimes even sunk into the sea. The Federal Environment Agency (UBA) expects an annual waste volume of around 15,000 t from used rotor blades alone in the near future in Germany, and the European Environment Agency assumes a figure of several million tonnes as total EU waste from wind turbines. Further research and development are evidently urgently required for the establishment and expansion of a functional recycling infrastructure. (39)

Another environmental problem relating to wind power arises from the insulating agent SF6 (sulphur hexafluoride) that is used in relatively small quantities (approximately 3 kg per wind turbine) in the electrical switchgear. Although SF6 offers a number of environmental advantages owing to its non-combustibility and other chemical properties and is considered physiologically harmless, it is also a highly potent greenhouse gas (with an impact on the climate that is more than 23,000 times greater than that of CO2), which is why its ban is being discussed at European level. SF6 can escape through accidents or material damage, but above all during the demolition of turbines. (40)

All the above-mentioned environmental problems also affect wind turbines on coal sites proportionately; general solutions would render the facilities obsolete, or they would remain in place until such solutions have been found. The further expansion of wind power as planned would obviously exacerbate these problems and heighten the pressure to find solutions so that any technological solutions are likely to be driven forward wherever possible.

In contrast, the consumption of raw materials associated with the expansion of wind power, which substantially exceeds that of conventional power generation plants, cannot be solved technologically, or at best only to a very limited extent. Tabbert, i. e., calculates that about 1,000 t steel, 73 t cast iron (hub), as much as 29 t composite materials, 12 t copper, 3 t aluminium and 2 t of rare earths (including as much as 600 kg neodymium) and, depending on the type of foundation, up to 6,000 t concrete are required for a single 3 MW onshore turbine from Enercon. He then used these figures to determine the average energy (620 MWh) and water consumption (1,200 to 2,300 m3) required for the extraction of these raw materials along with the resulting CO2 emissions (767 to 783 t) (using as a yardstick the German electricity mix) resulting mainly from the conventional steel and cement production that would be necessary. He also points out the overburden, waste and residues that are produced during the extraction of these raw materials such as arsenic or sulphuric acids during the mining of copper, so-called red mud during the production of aluminium, various dusts and acids as well as the radioactive strontium created during the extraction of neodymium, which is also very energy-intensive. (41)

The particular environmental problems of the extraction of rare earths such as neodymium, almost 90 % of which currently takes place in China, have already been discussed in more detail elsewhere, particularly with regard to the shift from coal to renewable energies. (42)

The fact that the raw material consumption of wind power plants per megawatt of output is significantly higher than that of conventional power plants across the entire supply chain was highlighted in Misereor’s 2015 study, “Raw Materials for the Energy Transition”. According to the study, wind power plants consume 15 times more cement per megawatt hour, 50 times more aluminium and up to 90 times more iron, copper and glass than coal-fired power plants (Figure 7).

Fig. 7. Supply chain wind energy and needed raw materials. // Bild 7. Lieferkette Windenergie und benötigte Rohstoffe. Source/Quelle: Carrara et al. 2020

Furthermore, in the countries and regions where these raw materials are mined, there are often far greater problems relating to compliance with standards for environmental protection, occupational health and safety and even human rights than in this country. (43) What effect the new German Supply Chain Act (Law on Corporate Due Diligence to Prevent Human Rights Violations in Supply Chains) that has been enacted in the meantime will have remains to be seen.

As far as the additional land consumption due to raw material extraction plus spoil heaps in Germany and abroad is concerned, Tabbert estimates that the area usage for German wind power plants would have to be calculated at ±10 % higher. Converted to the production capacity of an opencast pit lignite mine with an area of, say, 1,600 m2 that could be used for the generation of 40 GWh of electricity over 20 years, the land requirement is more than 28 times higher. This does not even include the areas for raw materials that are additionally needed for grids and storage such as battery buffering (lithium, cobalt, nickel etc.). However, for “energy production without digging holes” in Germany, this mainly concerns mining areas and “large holes” in mining areas abroad. (44)

From an overall perspective of this type that includes the extraction of raw materials, even the CO2 advantages of wind power become relative, at least in comparison to coal-fired power generation with CCS/CCU filtering. Tabbert presumes a filter performance for coal-fired power plants of 90 %. A reasonably well-running wind turbine with 2,000 MWh a year and more would still be able to save around 3,000 t CO2 over its lifetime, but a poorly-running wind turbine with only 500 MWh a year would have zero CO2 benefits. When compared to wind power plus the battery storage available at this time and its raw material balance, the CO2 effect would be negative in any realistic variant, i. e., CO2 emissions would be higher. Hydrogen as a storage medium for high-yield wind power, on the other hand, would reduce CO2 emissions, but would require considerably more water, additional land and immense additional costs for the construction of a nationwide hydrogen network with its own safety risks for the environment since hydrogen in a mixture with oxygen is also known as detonating gas because of its explosiveness. (45)

All the problems related to the extraction of raw materials for wind power outlined here will not only be exacerbated in the future by the technology’s further expansion in Germany, but will be raised to an even higher power because wind energy expansion in conjunction with the energy transition is supposed to be driven in other areas around the globe and to serve as a signpost on the path to climate neutrality. According to raw material information from the German Raw Materials Agency (DERA) at the Federal Institute for Geosciences and Natural Resources (BGR), all raw material consumption for wind power worldwide will roughly triple by 2040 compared to 2018 (46), which will certainly not be without impact on the availability and subsequently the prices of these raw materials (Table 3).

Table 3. Global demand for raw materials for wind turbines. // Tabelle 3. Weltweiter Bedarf an Rohstoffen für Windkraftanlagen. Source/Quelle: Statista 2023 (auf Basis BGR/DERA)

The Spektrum der Wissenschaft 2022 and other sources have clearly determined that the energy transition itself, and not only wind power, “is going to have a problem with raw materials”, namely, because of the increasing demand for metallic raw materials and other special raw materials with shortages and new dependencies on a few supplier countries. Solutions are possible, but will often be tedious and uncomfortable: i. e. (re)building of own mining capacities in Germany and Europe and massively expanding recycling. (47)

In this sense, the use of wind power on former coal sites can at least contribute to the conservation of scarce resources. Whether existing coal-fired power plants and mines, including those that employ CCS/CCU technology, should continue to be abandoned in favour of the expansion of wind power in the pursuit of energy and climate policy goals is, on the other hand, a question that demands a thorough re-examination from an overall perspective of area usage, environmental and raw material problems and the resulting economic costs.


As technology continues to advance, some of the problems described for wind power will probably be solved or at least mitigated. Intensive research is being carried out into the recyclability of rotor blades, e.g., and the first solutions, such as the RecyclableBlade concept presented by Siemens Gamesa in 2022, appear to be marketable. (48)

Political efforts to improve the framework conditions for the expansion of wind power and to remove obstacles are underway, and they can be of benefit to the transition of former coal sites on which wind power plants are planned. At the “Wind Summit” on 23 May 2023, the BMWK presented a new strategy for onshore wind energy that is intended to speed up the momentum of expansion and identify the adjustments that still need to be made. (49) The BMWK has designated twelve specific fields of action:

  1. Continue to use the provisions of the EEG to promote ­expansion.
  2. Support business models outside the EEG.
  3. Maintain existing systems and accelerate repowering.
  4. Mobilise more areas in the short term.
  5. Simplify and accelerate approval procedures.
  6. Facilitate the securing of areas.
  7. Strengthen social support.
  8. Strengthen added value and production capacities in Germany.
  9. Secure skilled workers.
  10. Facilitate transports of wind turbines.
  11. Drive technological development.
  12. Align more closely electricity grid expansion and wind ­energy expansion.

Some of these measures are already being implemented while the legal basis for other actions should be created as soon as possible. Former coal sites undoubtedly offer specific advantages, especially for points 4 or 6 and 7. Point 9, on the other hand, is a particular challenge because it requires targeted requalification measures and further training programmes. Regarding point 11, there is a general need for increased research funding for all aspects of wind technology.

For field of action 5 as well as for points 4, 6 and 7 and their relationship to coal sites, it is also very helpful when state and regional development planning carries out and confirms preliminary assessments concerning the examination of environmental compatibility and regional wind potential when designating suitable areas, as has already been initiated in North Rhine-Westphalia as one example.

Moreover, possible success in raising environmental standards in international mining, especially for the raw materials needed for wind turbines, and the expansion and deepening of the circular economy in this sector everywhere would appear to be extraordinarily helpful in solving the longer-term problems associated with wind power.

Sustainably improving location conditions for field of action 8 is of major significance for wind power and its added-value chains, although by no means restricted to this sector. This is essential for exploitation of the employment potential expected from the expansion of wind power (found largely in the manufacture of the turbines and their components) that would aid in compensating for the lost jobs in the coal sector. Achieving this goal, however, will require a more comprehensive economic and energy policy strategy approach for the improvement of sites ranging from internationally competitive electricity prices and secure energy supply to relief from bureaucratic red tape and regulations to advancements in the education and training of skilled workers for the future.

Furthermore, careful assessments of the suitability of wind power sites are crucial. The State Office for Nature, Environment and Consumer Protection (LANUV) in North Rhine-Westphalia presented an “Area Analysis Wind Energy North Rhine-Westphalia” for the state in June 2023. (50) The study concludes that there is a potential area of about 3.1 % of the state’s total area that can be used for additional wind farms. This figure clearly exceeds the “area contribution value” of 1.8 % set for North Rhine-Westphalia within the framework of the nationwide 2 % expansion target for wind power, so there is sufficient manoeuvring room for action and the design of regional planning. But this analysis also makes it clear that the opportunities for onshore wind energy expansion are by no means equally distributed regionally and that, depending on the planning region, specific concepts must be developed for each particular case and other planning considerations must be taken into account. This analysis of suitable land potential begins with numerous exclusion criteria for settlement and transport areas, bodies of water, infrastructure – including the opencast pit lignite mines still in operation in the Rhineland – military concerns, aviation safety, forest (not general), nature and landscape, biodiversity and various other issues and including proportionate community areas, areas that are too small, slopes and even inadequate wind conditions. It is also noted that nature, soil and architectural monuments, landscape conservation areas, ongoing land consolidation, pipelines, access roads, research infrastructures or reserve areas for the surface extraction of non-energy resources are not regarded as blanket exclusion criteria. The LANUV then carried out its GIS technical area analysis for the area potential defined according to the criteria and concluded that the area potential for wind power expansion is concentrated mainly in the peripheral areas of North Rhine-Westphalia. There is hardly any land potential to be found for many large cities in the Ruhr Valley and along the Rhine while the greatest potential has been identified in eastern Sauerland, in parts of East-Westphalia, in the north-west part of Münsterland and in the western part of the Cologne administrative district, including former lignite mining areas. The LANUV points out, however, that the interpretation of the results must take into account the “statewide prospects and the associated degree of abstraction.” Owing to the blanket assessment of exclusion criteria without consideration of specific cases and local circumstances, however, this is valid solely to a limited extent for a small-scale consideration of concrete areas or project planning. The NRW area analysis of wind energy does not aspire to the status of detailed site assessments and cannot replace analyses at the local level or project-related studies. Furthermore, it has no impact on planning and approval procedures at any given specific location. (51) In the Ruhr Valley, i.e., single waste dumps sites can still be considered as can the wind power potential of more rural sub-areas such as Recklinghausen District, while the LANUV sees almost no potential for densely populated metropolises such as Bochum.

References / Quellenverzeichnis

References / Quellenverzeichnis

(1) Siehe exemplarisch etwa den Endbericht von Prognos 2018 für das BMWi zu den Handlungsfeldern für die Strukturanpassung in den deutschen Braunkohlenregionen. Abrufbar unter: https://www.bmwk.de/Redaktion/DE/Publikationen/Wirtschaft/endbericht-prognos-zukuenftige-handlungsfelder-foerderung-von-massnahmen-zur-strukturanpassung-in-braunkohleregionen.html
Im letzten Jahr (2022) hielten Vertreter des Deutschen Instituts für Wirtschaftsforschung Berlin (DIW) auch angesichts der Energiekrise einen Kohleausstieg bis 2030 ohne russische Energielieferungen und trotz Atomausstieg durch beschleunigten Ausbau der Erneuerbaren, insbesondere der Windkraft, mit Blick auf eine sichere Stromversorgung für machbar; s. den Sonderbericht von C. Hauenstein, C. Kemfert et al. in DIW aktuell Nr. 81/20.4.2022, abrufbar unter https://www.diw.de/documents/publikationen/73/diw_01.c.839634.de/diw_aktuell_84.pdf.
Eine andere Auffassung vertritt dagegen aus energie- und regionalökonomischen Erwägungen K. van de Loo: Kohleausstieg aussetzen – Bestandsanlagen im Betrieb halten und verfügbare Kapazitäten reaktivieren, der Transition mehr Zeit geben. In: Mining Report Glückauf 158 (2022) Heft 6, S. 547 – 570, online: https://opus.thga.de/frontdoor/index/index/searchtype/all/docId/39/start/0/rows/10

(2) Siehe Vahrenholt, F. (2023): Die große Energiekrise und wie wir sie bewältigen können. München 2023, insb. S. 83ff.

(3) Siehe die einschlägige Website der EU-Kommission/GD Energy: Carbon capture, use and storage (europa.eu). Die EU-Kommission fördert CCS und CCU aktuell im Rahmen des FTE-Programms Horizon Europe sowie der Strategic Energy Technology Plan Working Group on CCUS und der damit assoziierten Europäischen Technologie- und Innovationsplattform „Zero Emissions Platform“.

(4) Siehe dazu die Darlegungen und die Datenbasis des Global CCS Institute. Abrufbar unter: https://www.globalccsinstitute.com/, zuletzt abgerufen am 12.4.2023;
zu aktuellen Schätzungen der Kosten für CCS in Europa einschließlich einer Kartierung sowie zu weitergehenden Analysen über die Kosten und Möglichkeiten der CO2-Abscheidung und -Lagerung in und außerhalb Europas siehe die Berechnungen des US-Think Tanks CATF (Clean Air Task Force) auf https://www.catf.us/de/ccs-cost-tool/
Zu den Plänen der Bundesregierung siehe u. a. Tagesschau vom 21.12.2022: Habeck will umstrittene CO2-Speicherung ermöglichen. Abrufbar unter: https://www.tagesschau.de/inland/gesellschaft/habeck-gasspeicherung-101.html,
ferner die BMWK-Website CCU/CCS: Baustein für eine klimaneutrale und wettbewerbsfähige Industrie. Abrufbar unter: https://www.bmwk.de/Redaktion/DE/Artikel/Industrie/weitere-entwicklung-ccs-technologien.html
sowie den SPIEGEL vom 13.5.2023, S. 96ff.: Der Bunkerplan. Klimakrise: Schon bald müssen weltweit gigantische CO2-Endlager entstehen.
Dass die Abscheidung von gut 90 % des CO2 im Abgas von Kohlekraftwerken zu Kosten von unter 30 €/t möglich ist, haben RWE, BASF und Linde mit dem Verfahren der OASE-Aminwäsche in einem mehrjährigen Pilotprojekt im Kraftwerk Niederaußem bereits vor einigen Jahren nachgewiesen, siehe P. Moser et al.: Das Forschungsprojekt zu CCS und Sektorkopplung im Innovationszentrum Kohle von RWE Power, VGB Power Tech 2019, S. 42 – 48 . Abrufbar bei: https://www.researchgate.net/publication/339602478_Die_Forschungsprojekte_zu_CCU_und_Sektorkopplung_im_Innovationzentrum_Kohle_der_RWE_Power

(5) Siehe Koalitionsausschuss der Bundesregierung: Modernisierungspaket für Klimaschutz und Planungsbeschleunigung vom 28.3.2023, S. 3. Abrufbar z. B. unter: https://www.spd.de/fileadmin/Dokumente/Beschluesse/20230328_Koalitionsausschuss.pdf

(6) Beispielhaft genannt seien der EU-beauftragte TRACER-Bericht vom März 2020 über „Ergebnisse, gewonnene Erkenntnisse und Leitlinien für den Übergang von Kohleregionen“. Abrufbar unter: https://tracer-h2020.eu/wp-content/uploads/2020/10/TRACER-D2.7_DE.pdf, ein Dossier der LZB Brandenburg von 2021 „Von der Kohle zu Wind und Sonne“ mit besonderem Bezug zur ostdeutschen Braunkohle. Abrufbar unter: https://www.politische-bildung-brandenburg.de/themen/so-ist-brandenburg/wirtschaft-und-arbeit/von-der-kohle-zu-wind-und-sonne. Die Wind statt Kohle-Debatte wird intensiv geführt auch auf europäischer Ebene, siehe diesen Beitrag von Wind Europe vom 14.7.2020: Wind energy is key to coal regions in transition and can support them cutting power sector emissions by half by 2030 | Wind­Europe, oder in den USA, vgl. den Artikel von Real Clear Energy vom 21.8.2021 Clash of the Titans: Wind Power vs Coal Power | RealClearEnergy.

(7) Speziell zur Nutzung der vom westdeutschen Steinkohlenbergbau hinterlassenen Haldenlandschaft im Ruhrrevier siehe die Potentialanalyse des Regionalverbands Ruhr (RVR) „Mehr Regenerative auf Halden produzieren“ laut der Mitteilung des RVR vom 26.8.2022: https://w3.windmesse.de/windenergie/pm/41802-regionalverband-ruhr-rvr-halde-erneuerbare-energie-photovoltaik-windkraft-flache-ruhrgebiet-standort-studie-potenzial-energieerzeugung; danach wird auf 8 der 58 verbandseigenen Halden schon Windenergie produziert und auf weiteren 23 Halden kommen nach den von der Standortstudie des beauftragten Büros EE Energy Engineers zugrunde gelegten Maßstäben zusätzliche neue Windkraftanlagen in Betracht.

(8) Siehe Näheres auf den Projekt-Websites Potentials Project – EU RFCS Project und https://greenjobsproject.uniovi.es/

(9) Siehe die Website von IRENA (2022): Wind energy (irena.org) sowie GWEC: Global Wind Report. Brussels. Online: https://gwec.net/global-wind-report-2022

(10) EurObserv’ER: Wind energy barometer 2022: Online: Wind energy barometer 2022 – EurObserv’ER(eurobserv-er.org) sowie Statistikangaben von Wind Europe für 2022. Download: https://windeurope.org/intelligence-platform/product/wind-energy-in-europe-2022-statistics-and-the-outlook-for-2023-2027

(11) Siehe die aktuellen Daten der Website von Quaschning: Weltweit installierte Windkraftleistung (volker-quaschning.de).

(12) BWE (Bundesverband Windenergie): Windenergie in Deutschland – Zahlen und Fakten. Abrufbar unter: Deutschland in Zahlen | BWE e.V. (https://www.wind-energie.de/).

(13) Siehe dazu die Zahlen und Daten im Jahresbericht der AG Energiebilanzen zum Primärenergieverbrauch in Deutschland 2022 sowie speziell zu den Erneuerbaren Energien: https://ag-energiebilanzen.de/wp-content/uploads/2023/01/AGEB_Jahresbericht2022_20230413-02_dt-1.pdf

(14) Vgl. Kaldellis, J. K.; Zafirakis, D. P.(2012): Trends, Prospects, and R&D Directions in Wind Turbine Technology. In: A. Sayigh (Ed.): Comprehensive Renewable Energy. S. 671-724. Online: https://doi.org/10.1016/B978-0-08-087872-0.00224-9

(15) Vgl. IEA-ETSAP/IRENA (2016): Wind Power. Technology Brief E07. Online: http://www.iea-etsap.org/Energy Technologies/Energy supply.asp

(16) Vgl. dazu die Angaben des Fachverbands der Elektrizitätswirtschaft BDEW 2021. Abrufbar unter: https://www.bdew.de/media/documents/20210930_Awh_BDEW-Fakten-und-Argumente_Versorgungssicherheit-Strom.pdf

Siehe auch die Dokumentation der Wissenschaftlichen Dienste des Deutschen Bundestags: Sicherstellung der Stromversorgung bei Dunkelflauten. Berlin 2019, in der u. a. auf die DWD-Studie verwiesen wird. Download: WD-5-167-18-pdf-data.pdf (bundestag.de).

(17) IRENA 2022: Renewable Power Generation Costs in 2021. Online: https://www.irena.org/Publications/2022/Jul/Renewable-Power-Generation-Costs-in-2021

(18) Vgl. Tabbert, A. (2022): Die Rechnung von Wind und Sonne. Ahrensburg, S. 92f.

(19) Siehe die Website Tech for Future (www.tech-for-future.de) und dort den Beitrag „Vollkosten pro kWh: Welche ist die günstigste Energiequelle 2022?“, online: https://www.tech-for-future.de/kosten-kwh/ sowie die angegeben Quellen. Abgerufen am 25.4.2023.

(20) Einen Überblick ihrer bisher fünf im Ruhrgebiet (ein weiteres im Saarrevier) zusammen mit Partnergesellschaften in Betrieb gesetzten Windkraftprojekte auf Haldenstandorten des vormaligen Steinkohlenbergbaus mit jeweils 1 bis 4 Windrädern gibt die RAG-Tochter RAG Montan Immobilien auf: https://www.rag-montan-immobilien.de/leistungen/erneuerbare-energien/wind-projekte/

(21) Zu den größten Windparks in deutschen Braunkohlengebieten zählen derzeit der bereits laufende RWE-Windpark Königshovener Höhe bei Bedburg mit 21 Windkraftanalgen à 3,2 MW (in der Summe 67 MW), das LEAG-Projekt Forst-Breisnig II beim Tagebau Jänschwalde mit 17 neuen 6 MW-Anlagen, 102 MW insgesamt, sowie ein Enercity-Projekt bei Nochten in der Oberlausitz, das mit 33 Windkraftanlagen der 6 MW-Klasse 200 MW Nennleistung an Kapazität bereitstellen soll.

(22) Überblick und vertiefende Einblicke in Methodik und Resultate von POTENTIALS liefert die unter (8) angegebene Projekt-Website. Die Nutzbarkeit der Windkraft auf ehemaligen Kohlestandorten und ihre Kompatibilität mit anderen Technologien wird auch in dem RFCS-Folgeprojekt GreenJobs, hier insb. unter Beschäftigungsaspekten, genauer untersucht.

(23) Vgl. Kapetaki, Z. et al. (Joint Research Center of the European Commission) (2020): Clean energy technologies in coal regions: opportunities for jobs and growth. Brussels. Download: https://publications.jrc.ec.europa.eu/repository/handle/JRC117938

(24) Siehe die Website der Fachagentur Windenergie an Land Herzlich Willkommen – Fachagentur Windenergie (fachagentur-windenergie.de) sowie dort die Daten der von ihr beauftragten Studie von Trendresearch zur Wertschöpfung in der Windindustrie in Nordrhein-Westfalen: https://www.trendresearch.de/windresearch/download/windresearch_Wertschoepfung_Wind_NRW.pdf

(25) Siehe WAZ Bochum vom 20.4.2023: Eickhoff-Gruppe schließt ein Werk. Unternehmen beendet die Produktion von Windkraft-Getrieben für Großkunden. 177 Mitarbeiter in Sachsen sind betroffen.

(26) Siehe die Tagesschau vom 7.2.2023. Abrufbar unter: https://www.tagesschau.de/wirtschaft/technologie/windkraft-siemens-gamesa-energy-verlust-windenergie-nachfrage-verfahren-101.html sowie
das Manager Magazin vom 29.9.2022: Siemens Gamesa streicht tausende Jobs. Online: https://www.manager-magazin.de/unternehmen/energie/siemens-gamesa-windanlagenbauer-will-tausende-stellen-streichen-a-a5f75c73-bf6d-4d62-9df4-de4eb8f0d3d9

(27) Vgl. Tabbert a.a.O., S. 111ff.

(28) Ebenda S. 114.

(29) Siehe Lehmann, P. et al. (2021): Optimal siting of onshore wind turbines: Local disamenities matter. UFZ Discussion Papers 4/2021, Leipzig. Download: https://www.ufz.de/export/data/global/255615_DP_2021_4_Lehmannetal.pdf

(30) Siehe die „Wortmeldung“ des KNE zum Flächenbedarf der Windenergie auf https://www.naturschutz-energiewende.de/unkategorisiert/wortmeldung-zum-flaechenbedarf-der-windenergie/

(31) Ebenda.

(32) Ebenda.

(33) Siehe Tabbert a.a.O., S. 175ff., insb. S. 178.

(34) Diese Abschätzung ist sogar noch konservativ gerechnet. Andere Experten kommen zu noch größeren Zahlen für den Flächenbedarf. Etwa Vahrenholt, a.a.O., S. 133ff., hält unter Berücksichtigung eines Abstands von 1.000 m zu Siedlungen aus Lärmschutzgründen sowie unter Abzug schon bebauter Gebiete, von Straßen, Gewässern und Naturschutzgebieten einen Anteil von 15 bis 20 % für realistisch. Er kommt zu dem Schluss: „In der freien Landschaft wird es kaum noch einen freien Horizont geben.“

(35) Ntambakwa, E.; Yu, H.; Guzman, C.; Rogers, M. (2016): Geotechnical design consideration for onshore wind turbines shallow foundations. Proceedings of the Geotechnical and Structural Engineering Congress, Phoenix/Arizona, USA. Download: https://www.researchgate.net/publication/312600108_Geotechnical_Design_Considerations_for_Onshore_Wind_Turbine_Shallow_Foundations

(36) Ebenda.

(37) Siehe Broschüre der Keller Group: Wind Farms. Geotechnical Solutions for the construction industry. Download: https://www.keller.com/sites/keller-group/files/2021-02/keller-brochure-sector-wind-farms.pdf. Zuletzt abgerufen am 10.5.2023.

(38) Aktualisierte Übersichten liefert das von der Organisation Vernunftkraft aufgestellte „WKA-Unfallregister“: Online: https://www.vernunftkraft.de/

(39) Siehe WAZ vom 18.4.2023: Der Haken an der Windenergie.

(40) Das SF6-Problem der Windkraft ist sogar schon in der Tagesschau berichtet worden: https://www.tagesschau.de/wirtschaft/technologie/erneuerbare-energien-windkraft-treibhausgas-sf6-101.html. Eine recht umfassende Darlegung und Einordnung findet sich auf https://energiewende.eu/windkraft-sf6/

(41) Siehe Tabbert, a.a.O., S. 185f.

(42) Siehe Tiganj, J.; Rudolph, T. (2023): Die Ausrichtung einer kohlenstoffarmen Wirtschaft am Beispiel Chinas: Die Vor- und Nachteile eines Umschwungs von Kohle zu erneuerbaren Energien. In: Mining Report Glückauf 159 (2023) Heft 1, S. 17 – 24.

(43) MISEREOR (2015): Rohstoffe für die Energiewende. Aachen. Download: https://www.misereor.de/fileadmin/publikationen/studie-rohstoffe-fuer-die-energiewende.pdf

(44) Siehe Tabbert, a.a.O., S. 186ff.

(45) Ebenda sowie S. 211f.

(46) Siehe Studie Fraunhofer ISI/Fraunhofer IZM im Auftrag der DERA (2021): Rohstoffe für Zukunftstechnologien. DERA-Rohstoffinformation. Download: https://www.deutsche-rohstoffagentur.de/DE/Gemeinsames/Produkte/Downloads/DERA_Rohstoffinformationen/rohstoffinformationen-50.pdf?__blob=publicationFile&v=4

(47) https://www.spektrum.de/news/fuer-die-energiewende-werden-die-rohstoffe-knapp/2005387

(48) https://www.windkraft-journal.de/2022/09/22/siemens-gamesa-praesentiert-recycelbare-rotorblaetter/179686

(49) Siehe Pressemitteilung des BMWK vom 23.5.2023: Neue Dynamik beim Windausbau an Land. Abrufbar unter: https://www.bmwk.de/Redaktion/DE/Pressemitteilungen/2023/05/20230523-neue-dynamik-beim-wind-ausbau-an-land.html

(50) LANUV (2023): Flächenanalyse Windenergie Nordrhein-Westfalen. Fachbericht 142. Download: https://www.lanuv.nrw.de/fileadmin/lanuvpubl/3_fachberichte/LANUV-Fachbericht_142.pdf

(51) Ebenda S. 5.

Authors/Autoren: Prof. Dr. Kai van de Loo, Julia Haske M. A., Forschungszentrum Nachbergbau (FZN), Technische Hochschule Georg Agricola (THGA), Bochum/Germany