ABSTRACT

According to Recycle Magazine’s report, the wind energy sector currently uses nearly 2.5 million tons of composite materials. In Europe alone, we shall expect decommissioning of almost 12 000 wind turbines in the next five years.^[1] The regulations regarding wind turbine dismantling vary with countries, but there is no international standard to date.^[2] From the few existing experiences, the decommissioning process is affected by high uncertainties and many unexpected challenges, but mainly the absence of a global regulatory framework.

This article aims to review, analyze, and document the impact of wind turbine dismantling and call international energy organizations to advocate for global standard regulation of the decommissioning, repowering, dismantling, and recycling wind turbines.

Introduction

Wind energy has gained a share of the global energy mix for the last two decades. Indeed, its installed capacity has increased from 6100MW in 1996^[3] to 743GW in 2020, with 5.2% of the global electricity supply share in 2019.^[4] The beginning of the twenty-first century has seen the first large turbines at the end of their lifetime in Germany, Denmark, the United States (US), and other countries. According to IRENA’s report, a quarter of North America’s wind turbine fleet should reach the end of its life span by 2030.[5]

Whether the manufacturers and wind power developers knew that wind power systems had a lifespan of about twenty years, the start of dismantling them came with several challenges.[6] Indeed, developers were not prepared for the related expenses, the recycling capacity, the repowering, and the actual financial and environmental impact of wind power when considering its entire life cycle.

The impact of dismantling wind turbines at their end of lifetime

The lifespan of wind turbines depends on the physical evolution of their components. Still, it is also a function of the strategy followed by the operators during the period of validity of the feed-in tariffs. The impact of repowering operations after fifteen years, as seems to be the case for recently dismantled parks, can, in particular, generate more significant waste flows than expected in the years to come. The general economy and the industrialization of treatment channels for wind turbines at the end of their lives must be consistent with the environmental principles underlying the circular economy and the financial balance of the various economic players.

The description of the regulatory framework makes it possible to situate the sector in the face of environmental issues, including the end of life and the circular economy on the one hand and the development of renewable energies on the other. In particular, we can underline that the sector is growing, and given the age of the fleet, there are few end-of-life feedbacks. The dismantling operations use techniques available on the market (lifting, craning, and exceptional transport). Most materials enter structured and identified collection, sorting, re-use, or even recycling channels (concrete, steel, and non-steel metals, electrical and electronic equipment). The landfill at this stage only concerns the concrete (in part), the composite blades, and, in small quantities, the rare-earth of the permanent magnets. The thermal recovery of blades in cement works, widespread in Austria, Finland, Germany, and the Netherlands, where landfilling is prohibited, is also practiced in several other countries.[7] Finally, we should note that several players favor a total dismantling of the reinforced concrete anchoring blocks, going beyond the regulatory requirements in certain countries where the demolition of one meter deep is sufficient.

Wind turbines life cycle

The life cycle analysis allows evaluating wind energy’s financial, social and environmental impact. It considers the extraction of raw materials and the power involved, the transformation of raw materials and the manufacturing, transport, distribution, use, end-of-life recycling, and the impact on the community. Furthermore, I will review the supply chain from the manufacturing of wind turbines to their retirement and explore difficulties related to recycling some parts of the wind turbine, the repowering, and the dismantling.

Manufacturing and installation

The investment costs or capital expenditure (CAPEX) represent the central part of the costs of an onshore wind farm. The purchase of wind turbines is the first item, accounting for nearly three-quarters of the total investment. Table 1 gives an average distribution of the main cost items constituting the investment to set up wind power. On average, for each megawatt of installed capacity, a wind turbine requires 103 tons of metal for the mast, 402 tons of concrete and scrap for the foundations, the fiberglass blades weight 6.8 tons, 3 tons of copper, and 20 tons of cast iron for the generator.[8]  The data collected can vary significantly between the different projects analyzed, from one country to another.^[9]

The impact of transport varies because it depends on the manufacturer’s site and the installation site. The construction and installation phase of the power plant also leads to energy consumption linked to the assembly of the wind turbine. Part of the energy serves to assemble the wind turbine on its foundations and to secure the blades to the rotor using cranes. Therefore, access roads represent an essential part of land consumption. However, wind power sites are often far from existing infrastructure due to the requirement of a distance of 500m from homes and the prohibition on overhanging public spaces such as roads.

Therefore, the creation of dedicated access routes is often essential. To transport masts weighing up to 150 tons and blades over 50m long, you need a track 5m wide and with a slight curvature in the bends. The assembly and hoisting areas of the edges also represent a part of the land consumption. However, solutions such as assembling the rotor blades in the air allow the reduction of the footprint. Land consumption is, therefore, about 0.5 hectares per wind turbine. According to the IRENA’s report, the studies, equipment, connection, installation, and commissioning costs of an industrial wind turbine decreased from $1913 in 2010 to $1497 in 2018 per MW of wind power. Besides the offshore wind, they dropped from $4572 to $4353 in the same period, and there is an expectation the prices will continue falling.[10]

The total cost per kW of installed wind power capacity differs significantly between countries. Still, the cost structure of a typical 2MW wind turbine shows that 75.6% of the investment goes to the purchase of the wind turbine, which confirms that the performance of the manufacturers in producing cost-effective machines shall impact the installation cost. Wind turbines at sea are more expensive due to installation, connection, and maintenance costs.[11]

Operation and maintenance

The maintenance cost is a significant part of the overall Levelized cost of electricity (LCOE) of wind power. They can account for between 11% and 30% of onshore wind LCOE and typically account for 20% to 25% of the total LCOE of current wind power systems. However, if the turbine is relatively new, the share is only 10-15%, increasing to 20-35% by the end of the turbine’s life.[12] Thus, they are a significant issue for manufacturers attempting to reduce them significantly by developing new turbine designs that require fewer scheduled service visits and significantly reducing turbine downtime.

Operation and maintenance costs include insurance, regular maintenance, repair, spare parts, and administration. Some of these cost items can be estimated quite easily. For insurance and routine maintenance, it is possible to obtain standard contracts covering a considerable part of the total life of the wind turbine. Note that all cost items tend to increase as the turbine ages.[13] However, repair costs and spare parts are much more difficult to predict and vary with the age of the turbine. Due to the relative newness of the wind power industry, only a few wind turbines have reached their 20-year life expectancy. Their turbines are much smaller than those currently available on the market, and to some extent, their design standards have been more conservative, albeit less stringent than those of today. Thus, estimates of operating and maintenance costs are unpredictable, especially towards the end of a wind turbine’s life. However, we can learn from some experience from existing, older turbines.

Based on experiences in the US, Germany, Spain, UK, and Denmark, operation and maintenance costs vary between $0.01 to $0.02 per kWh of wind energy produced during the entire life.[14] Economies of scale may exist for operation and maintenance costs. The new and more giant turbines respond better to the sizing criteria than the old models, implying a reduced life with more demanding maintenance and upkeep requirements. However, this can also affect that these new turbines do not withstand unexpected events as effectively.

Wind turbines dismantling

The law requires the dismantling of wind turbines at the end of their life, estimated at twenty years, on average. Let’s consider the same example cited previously of a one-megawatt turbine, 120 meters high. It contains 103 tons of steel, resin, rare metals, and other various polluting components, sealed on a mass of heavily scrapped concrete of 402 tons. The amount of materials increases with the power capacity, and the actual wind turbines can double this quantity and occupy more space. However, all the wind turbines, domestic and industrial, shall dismantle independently of the power capacity.

In two decades, the wind operators who will dismantle it must, by law, level the top meter of the concrete base, in order, in principle, to allow the plot to return to cultivation. He will logically crush the rest of the foundation, more than three meters deep, to allow water to rise. Otherwise, the plot will be unfit for agriculture. These works constitute a large whole; however, to ensure their completion, wind power operators have the sole duty of presenting a bank guarantee of  €50,000 per mast in France, 6.5% of the total price of the installation in Germany.[15] In the United States, each state fixes the guarantee amount, and in some states, there is no warranty requirement for dismantling. In all cases, planned or not, this amount is insufficient for the work to be done. Indeed, according to the American author Rick Kelley, it would be necessary to foresee at least $200,000 for the dismantling of each wind turbine.[16]

A study conducted by the multinational group Gutteridge Haskins & Davey (GHD Group Pty Ltd.) specialized in engineering services for the City of New York in 2017, estimating the dismantling cost of Cassadaga wind farm composed of 48 Gamesa 126 – 2.625 MW turbines with a height of 102 meters, has concluded to a total decommissioning amount of $7,996,500, with a total salvage value for all 48 wind turbines of an amount of $7,802,000 leaving a balance cost of $194,500. [17] The study considered removal depth of the foundation at a minimum of 1m below grade for foundations. It does not include dismantling the maintenance and operation building that should continue serving for other purposes.[18]

The cost is justified mainly by using a 700 tons crane, two 50 tons cranes, a mobile shear press, and other types of machinery. It increases because of the maintenance of a team of workers during unbolting, torching, and shearing of the parts metal, conditioning, and landfill of non-recoverable parts, mainly the blades (20 tons of non-recyclable materials). In addition, consideration of climatic hazards, for safety reasons, can delay work and therefore immobilize the equipment for an indefinite period.

In the current absence of an established recycling channel due to the weakness of this emerging market, the actual costs are certainly higher. But we can expect that, within a few years, as more and more wind farms can dismantle, candidates will increase and become more professional, backed by the idea that developers will want to be irreproachable even if they did not budget. Nevertheless, the fact remains that in cruising speed, the resale of recycled products will bring only marginal sums under the current conditions of the recycling market. In addition, the cost of dismantling depends on the number of wind turbines to dismantle. However, there is a market for second-hand turbines growing due to increased demand from Eastern European countries and the waiting list for new turbines. Furthermore, the time required for the new turbines forced some buyers into the second-hand market to meet the European Union’s CO2 reduction targets.

Moreover, used turbines cost 40% less than new turbines. However, purchasing the second-hand wind turbine represents a risk because they do not know its history. It was working for at least 15 years, which means that the constitutive materials have inevitable fatigue.[19] However, continuous research progress should use better materials to manufacture wind turbines that would have a longer life without exposing the neighborhood to risks of accidents.

Recycling processes

The wind farm dismantling operation follows law regulation and includes the entire facility recycling process on the operator’s responsibility. It requires the dismantling of electricity production facilities, delivery stations, and cables within a radius of ten meters around wind turbines and delivery stations. It includes excavating the entire foundation from the footings and replace it with soil of the same characteristics as in place near the installation. It also requires filing with the earth the crane areas and access roads. The demolition and dismantling waste is re-used, recycled, recovered, or, failing that, eliminated in the channels duly authorized for this purpose. About 90% of the wind turbines must be dismantled, including the foundations, or 85% when the foundations’ excavation has an exemption. They must be re-used or recycled and at least 35% of the mass of the rotors.

Wind turbines are classified installations for protecting the environment, which requires anticipating the question of dismantling, taking into account the administration’s advice and the landowner. If the operator fails, there is a provision of site restoration operations by financial guarantees before the installation, varying from country to country. Today, it is possible to recover at least 90% of a wind turbine at the end of its life, which allows the operator a return on investment for the materials used.^[20] Another alternative to recycling is the resale of spare parts after dismantling. When the wind turbine lifetime arrives, some dismantled parts, especially those not subject to mechanical stress, like mechanical and electrical components of the turbine, are in good working status and shall serve in the existing wind turbine parks.

Metal parts recycling

Recycling the metal parts such as the mast and the rotor go through existing channels. The market value of this scrap metal often makes the dismantling of a wind turbine a profitable operation. Rare metals are sometimes used but do not pose any particular supply problems. The rare earths mainly used in wind power are neodymium (Nd2O3, Neodymium oxide) and dysprosium. It is the neodymium/iron/boron alloy, which is particularly interesting in wind power. Still, it must be doped with dysprosium to work in wide temperature ranges because it loses its magnetic properties below a specific temperature level.

Studies to date show that a wind turbine uses 600-700 kg of magnets per MW of capacity, including 25-29% neodymium and 4% dysprosium in the permanent magnet of the generator.[21] They serve for their magnetic properties in wind turbines with permanent magnets. Rare-earth magnets are not rare. Their criticality comes from China’s current virtual monopoly for their extraction and processing. China accounted for about 71% of the world’s production of rare-earth magnets in 2018.[22] Like all mining and metallurgical processing, their extraction has environmental impacts. The environmental specificity of rare-earth extraction compared to other metals comes from thorium and uranium in so-called rock deposits, which induce radioactive pollution from the various discharges. Their consumption in the renewable energy production sector lies mainly in permanent magnets for offshore wind power. Only a tiny proportion of onshore wind turbines use them. According to a wind capacity at sea projected at 180 GW globally, and concerning the world annual production of rare-earth magnets, the need represents less than 6% of the yearly production of neodymium and more than 30% of dysprosium.[23]

It is quite possible to design wind turbines without rare-earth magnets; it is only a question of the technological choice of the manufacturer. Alternative solutions exist; asynchronous generators or synchronous generators without permanent magnets, for example. The rational integration of a certain quantity of recycled magnets in future magnet production looks promising. Indeed, it would be possible to produce magnets with performance comparable to those of the trade by using up to 30% recycled material. Projects are developing a closed-loop system from permanent waste magnets to create new products to recycle those materials. The first approach, extracting the ionic liquid, removes rare earth from waste streams in oxalates. The second, high-temperature electrolysis (HTE), produces a rare earth alloy from rare earth/oxide mixtures obtained after calcining rare earth/oxalate mixtures from the ionic liquid extraction process. The advantage lies in the bespoke HTE process because it eliminates the separation and conversion steps of individual rare earth oxides or halides in the Chinese primary processing (mining) process.

Therefore, this technology leads to a more efficient and environmentally sustainable approach, as it avoids many unique extraction steps. These new personalized technologies allow the treatment of this waste containing rare earth from permanent magnets to serve as permanent magnets from end-of-life products to produce an intermediate alloy containing rare earth. It proceeds by a continuous molding process called strip casting to obtain a rare earth master alloy to manufacture permanent magnets, thus achieving a complete closed-loop permanent recycling process. This sector offers a competitive cost and an excellent environmental footprint compared to conventional primary extraction of rare earth. The whole closed-loop recycling process of permanent magnets, from waste containing rare earth to new products in the form of rare earth permanent magnets, has been demonstrated on a pilot scale.[24]

Concrete recycling

The concrete resulting from the deconstruction of a wind turbine has two sources: the foundations and the mast, which can be steel or concrete. For the concrete of the foundations, the regulations do not systematically impose its excavation. Still, it appears in the agreement of private law, entered into between the owner of the land and the wind farm operator at the end of its life. In practice, in the frequent case of repowering with exact siting of new wind turbines, the old foundations are systematically removed, regardless of their depth. Quantitatively, the concrete from the foundations represents the most significant mass, up to three times that of the wind generator itself. For onshore wind turbines, concrete represents 84% ​​of the total wind turbine.[25]

In practice, this concrete waste is currently used on public works sites as road underlayments and backfill and as backfill material for quarries whose operators are required to fill the voids created. More ambitiously, the sector actors engaged in another form of recovery, more anchored in the logic of the circular economy: re-use the aggregates resulting from the crushing of deconstruction concrete to manufacture again concrete presenting satisfactory technical, economic, and environmental performance. In the end, the concrete resulting from the dismantling of wind turbines follows the treatment channels for concrete recycling in general. It does not present any environmental impact other than the greenhouse gas (GHG) emissions linked to road transport. However, it has a cost, which is not negligible given the quantities involved, for those interested in dismantling and recycling. Therefore, accurate recycling in the concrete manufacturing sector is possible in the medium term and would improve the economic equation of dismantling a wind farm. In addition, wind turbine manufacturers could consider using recycled concrete, subject to a guarantee of mechanical strength.[26]

Under normal circumstances, concrete can remain in place as a relatively inert material. Concrete is inherently durable unless attacked by aggressive agents, such as soils containing sulfates or low pH below 7. The risk of rebar corrosion is common in buried concrete due to the low risk of carbonation and lack of oxygen. However, this could depend on the final shape of the landform, and it may be necessary to remove part of the foundation structure.[27]

Energy security and climate change

Wind turbine blades, and to a lesser extent the nacelle, are made of several different materials and mainly a thermosetting polymer matrix (epoxy or polyester resin) with reinforcing fibers (glass and carbon fibers) inserted into the matrix. In addition, they consist of a light wooden or PVC foam core and assembly materials: glues and screws. It is, therefore, a sandwich structure with the presence of a composite material. The composite material represents the bulk by weight, consisting of 65-75% reinforcing fibers and 50-40% resin.[28] The reinforcing fibers are glass fibers. For the most powerful wind turbines (3MW and beyond), carbon fiber makes it possible to stiffen increasingly long blades.[29] The dynamics of this market are indeed strong, especially for offshore wind energy and the replacement of dismantled machines at their end-of-life time.[30] The processing of composite materials from wind turbine blades does not present any particularity compared to the general problem of processing all mixed waste. Suppose we refer to the hierarchy of treatments set by the waste directive above. In that case, we should first promote the material recycling of these materials before considering their energy recovery, the ultimate solution to prevent them from being landfilled.

The optimal mode of treatment would consist of a chemical or thermal process in dissociating the plastic matrix and the fibers to reintegrate these products into new products. In particular, industrial are interested in its recovery, which has a higher added value than thermosetting resins. Such processes exist: they are solvolysis and pyrolysis.[31] Solvolysis immerses the composite in a reactor with reactive solvents, thus making it possible to decompose the matrix and recover the fibers. This process remains at the laboratory stage. Pyrolysis makes it possible to break the bonds between the fibers and the matrix by heating at high temperatures in a treatment chamber. Unfortunately, this treatment dramatically degrades the mechanical properties of glass fibers, making them unsuitable for re-use, similar to virgin fibers.

On the other hand, it is suitable for recovering carbon fibers, keeping mechanical characteristics almost identical to virgin fibers. The process is also very energy-intensive. Its environmental record is therefore very open to criticism. For technological and economic reasons, it shall go beyond the recovery of carbon fibers that are still limited but destined to grow in the long term in the blades of wind turbines. Since the consideration of fiber recycling is for carbon fiber, the players shall consider a synergy with aeronautics, the leading application sector for carbon fiber-based composites.

Another rustic material recycling method consists of grinding the entire composite and, after several mechanical operations, obtaining a compound or grind, a mixture of resin and very short fiber with well-controlled particle size characteristics. This product can then be reintroduced into a production line for products based on composites, thus saving raw material. On the other hand, its properties are inferior to virgin material, limiting its use to the less demanding services of the composite. Several concrete experiences: manufacturing road barriers, railway sleepers, patio tiles, street furniture (children’s games, bus shelters, etc.). None of these particular applications resulted in a significant market. The cause of the failure is that the composite competes with conventional materials like concrete, wood, and unreinforced plastic for these applications. The wind industry would be interested in approaching this initiative to consider a technical and economic opening of the construction and public works markets to recycled composites.[32]

Another type of recycling is the energy recovery of non-hazardous waste, done in incineration plants that process household waste. Since wind turbine blade waste is not hazardous waste, it can go directly to the ordinary industrial waste incineration plant. However, this solution has two limitations. First of all, a quantitative limit: a dismantling site will locally and instantly produce in 24 to 48 hours a relatively large amount of waste to be eliminated quickly. The availability of a neighboring incineration plant is not guaranteed. Then, a possible qualitative limit: the incineration plant manager, until then little used to treating this type of waste, could argue from the constraints of his specifications to refuse it (cf. in particular the presence of PVC, likely to emit chlorine on combustion). Incineration in a dedicated hazardous waste treatment facility would be technically possible (who can do the most can do the least), but economically prohibitive: the cost of treatment in this type of facility is high. There is, therefore, still the possibility of recovering it in cement factories.

On the other hand, the blades of a wind turbine in composite materials made from glass or carbon fibers are difficult to recycle. The industry, therefore, mobilized to find solutions. The problem is also more significant than that of recycling wind turbines since these same materials serve for many other applications, such as, for example, the hulls of boats and kayaks, sailboards, tanks, body parts in automotive construction parts for aeronautics, etc.

The first difficulty is the size of these blades. Their length varies between 20 and 50 meters but can be much longer. It would be expensive and time-consuming to transport them in one piece to recycling plants. It is the reason that prompted some companies to develop a giant saw blade for wind turbines that allows them to be cut into pieces directly on-site, making their transport easier. They can then be crushed and used as fuel in cement factories, replacing fossil fuels. The ash serves as a raw material in the manufacture of cement. This technology, therefore, avoids the production of waste.

Another possibility is using turbine blades to make new composite materials. It is notably the solution developed by the University of Washington in collaboration with General Electric (GE) and Global Fiberglass Solutions Inc (GFSI) of Seattle. The product obtained from the grinding of the blades would be as strong as the wood-based composites. As a result, many uses can be envisaged, such as floor slabs, guardrails along highways, maintenance hole covers, skateboards, furniture, or building panels. According to Evan Milberg, GFSI recycled 564 blades in less than a year using this method. The company estimates that it could turn more than 25,000 tons of waste composites into valuable products in two years.^[33]

Repowering process

In the wind industry, the term repowering is well known. Concretely, this term refers to taking advantage of innovations and replacing old wind turbines with more efficient models. Wind farms beyond 15 years still have value, but they suffer from a limited remaining lifespan and an uncertain selling price of electricity following the end of their lives.[34] The future safety of wind parks depends on the time it takes to get repowering authorizations: both its lifespan and its selling price of electricity with visibility over 20 years. By installing more giant turbines, increases the value of wind farms. Repowering means actively participating in the achievement of energy transition objectives. These wind farms near the end of their lives (15 years) can often operate for an additional 5 to 10 years. Still, without renewal, it will inevitably lead to a drop in renewable energy capacities.[35]

The renewed parks increase their production, which will ultimately boost the production of green electricity. By restoring a wind farm, it is possible to double its production. Unfortunately, the first wind farms are getting old. They were built from 2000 to 2006 with small wind turbines, inefficient compared to current technologies. Many wind farms are in areas that are now incompatible with wind development due to regulations put in place after their construction. The aeronautical and radar constraints mainly impact the capacity of repowering increase. This issue is significant and complex. Therefore, to allow the potential of repowering, the authorities in charge of this zoning must agree to open constructive dialogues with project leaders and their professional organizations’ aim of bringing together these existing activities.

Citizen participation is a formidable tool for the appropriation of renewable energy projects by territories and residents. These arrangements are becoming increasingly crucial for wind projects. Repowering projects are generally better accepted locally than new projects because local stakeholders are already familiar with wind energy and its integration in their territory.[36] They often see the advantages of repowering: renovating the wind farm, producing more without adding new masts, and thus perpetuating this activity, as well as the tax revenue it brings to the territory.

Repowering means either replacing entire wind turbine system components (full repowering) or upgrading older turbines. However, it can replace specific parts (rotor, gearbox) with advanced and efficient technologies without replacing the whole structure (partial repowering). In addition, some components like the foundation and tower may continue operation after complex and specific assessment to withstand an additional 10 to 20 years. Sometimes, the repowering occurs years before the end of the technical lifetime of wind plants due to economic gains and resource utilization purposes at the older, best resource sites with improved technology design potential.[37]

If the site is repowered, deciding whether to remove existing infrastructure can be even more complicated. In some circumstances, the retention of infrastructure and overlaying of new infrastructure could lead to significant long-term or even permanent combined impacts on the site’s landscape and the amenity of neighboring receptors. Wherever possible, preference goes to the adaption and re-use of existing infrastructure. Where this is not possible, the new infrastructure respect the limit of the amount of new infrastructure required minimizes the size and extent of new infrastructure. It should be consistent with (or improve upon) the original pattern and character of existing site infrastructure and follow good practice regarding its landscape fit and relationship with the design, scale, and form of existing landscape elements. In case there are significant landscape and visual effects anticipated due to the combined development of the existing and proposed infrastructure, in that case, the removal (or partial removal) of existing infrastructure is advisable.[38]

Energy security and climate change

The impact of a wind project on the landscape is fully reversible. A wind farm has the advantage of being removable, and site rehabilitation can take place at the end of the farm’s operation if there is no renewal of the wind turbines. The costs of dismantling are known and controlled, and financial guarantees must be provided before the commissioning of the wind farm and placed under prefectural control. All the components of the wind turbine and the associated infrastructure are recoverable. The regulations impose foundations leveling to a depth of 1m, depending on the use of the soil.[39] The concrete mass left in the ground is in no way a source of pollution since it is an inert material, that is to say, one which does not exchange with the environment in which it occurs. This reversibility is interesting from a landscape point of view and an economic point of view. It allows the farmer to recover the surface of his plot modified to reintegrate it into his farm.

In the case of dismantling a certain number of wind turbines, in addition to the cost of dismantling and the technical difficulties of recycling certain parts (such as blades), there is also an installed power capacity that decreases. The decrease may disturb the balance and the availability of the network. The ideal would be to put into service other turbines of the same capacity or higher capacity or fill the void left by the dismantled machines with another source of energy that was not in the network.

Environmental impact

Four principal elements compose a wind turbine: The rotor made up of blades, which converts kinetic energy into mechanical energy, the nacelle, which most differentiates manufacturers, is the place of electromechanical conversion, we find the shaft -multiplier, the generator, and the transformer, the mast, which supports the nacelle and the rotor, and the foundations, which allow anchorage of the wind turbine to the ground.

The first environmental impact of the wind turbine is manifested directly through the manufacturing process of the various components. Indeed, as we have seen previously, the wind turbine comprises many metals (about 103 tons if we keep the same example cited above). The process of extracting these metals from mines leaves a significant impact on the environment in erosion and pollution. During metal processing work, there are also several types of environmental impact through the evaporation of certain products, waste of all kinds, and the energy used for processing. In most cases, this energy comes from fossil fuels which are not renewable.

It has a lot of concrete composing the foundation (402 tons)—the cement for the concrete, which comes from a similar process and leaves different environmental impacts. Bulkier due to the difficulty of being recycled, these are the fiberglass blades (6.8 tones for our example). These giant pieces have yet to find adequate technology for full recycling. Essentially designed from a mixture of epoxy resin or polyesters and fiberglass, the most recent blades also incorporate carbon fiber to stiffen longer lengths. In the last twenty years, the diameter of the rotors has increased from 20 to 108 meters, with the possibility for the blades to reach 250 meters for offshore wind turbines.[40] In addition, each edge contains electronics, lightning protection wire, adhesive, etc., a heterogeneous mass representing 5 to 10 tons and currently has limited prospects for recovery. Now, the blades end up at best, valued for energy, at worst buried in a landfill. The operation consists of shredding and possibly crushing them before introducing them into a cement kiln to replace fuel oil. The shreds can serve in the constitution of solid recovered fuels but at a dissuasive cost. It is also the case in the maritime industry which also uses a large number of fiberglass composites. There is no material recovery channel because the deposit is still scattered to justify creating a recycling channel. Globally, according to Vanessa Schipani, the wind farm’s emission rate is 11-14gCO2.eq/kWh, one of the lowest in the energy production sector.[41]

Wind power is responsible for very little soil acidification. However, land surface use is high due to access roads. As most wind farms are in agricultural areas, the construction of wind turbines can compete with agriculture. Concrete has a negative impact, especially on the manufacturing and transportation phases with carbon dioxide emissions. However, the effect of concrete on the surrounding environment is low because its presence is a very localized and inert material. Wind power represents a small percentage of national concrete production, at least not much compared to other sectors.

Financial impact

Currently, the wind industry generates tens of thousands of jobs around the world. As an indication, according to the Global Wind Energy Council (GWEC), the wind industry has the capacity of creating 3.3 million jobs within five years.[42] Evaluating the indirect employment generated by the wind industry is not easy. Still, an overall estimate shows that one megawatt of wind indirectly creates 15-19 jobs per year under current European market conditions.[43] We should also note that the great diversity of activities involved in the installation of wind farms: research and development (universities, engineering companies), project development (consultants, promoters, lawyers, financial companies, etc.), manufacture (of components, wind turbines, certification agents), construction (civil engineering companies, electrical engineering, transport, lifting), operation (operation and maintenance companies, repair), commissioning and decommissioning (civil, electrical and lifting, transportation). Faced with developing the wind energy sector, new professions and new training courses appear, ranging from technological baccalaureate to master’s, including professional licenses to specialized institutes.

The offshore wind sector is a promising source of diversification for companies specializing in shipbuilding, industrial boiler making, specialists in composite materials. Structural work and electrical installation, maintenance, and monitoring generate local and regional jobs. Wind turbines also generate local economic benefits through the rents paid to landowners and operators. Finally, the taxes generated allow municipalities and other local authorities to make local investments to improve the living environment of residents. Therefore, the wind energy sector contributes to creating jobs in the construction sector, which locally contributes to the economy linked to catering and accommodation. The operation of the wind turbines will result during the operation phase of significant positive economic impacts due to the economic benefits it generates and the maintenance of the wind farm. Once installed, the wind farm operation has a positive economic impact thanks to the economic benefits it generates. During the wind farm operation, the tax benefits for local authorities are of several types: the reform of the professional tax has implemented the territorial economic contribution and the flat-rate tax on network companies. The tax on built property supplements these taxes. According to IRENA, wind power now employs 1.2 million people, over one-fifth of them women. Sector-wide, renewables show a better gender balance (32% women) than fossil fuels (22%).[44]

Role of states and international energy agencies in regulating wind turbines dismantling processes

Wind turbines are installations that have become common in many countries. The regulations for the installation of wind turbines exist in different forms depending on the country. There is also an international standardization of their building at various equipment manufacture, installation, and operation stages through environmental impact studies. Still, there is no dismantling regulation at the international level.

Role of the states in setting up wind turbine dismantling regulations

According to the GWEC in its global wind report 2021, European countries have higher wind energy penetration, with Denmark at the top with 40% of production and Ireland with 28%. However, China still leads as the country producing more energy by the wind with an installed capacity of 236,402 MW, followed by the US with 105,466 MW.[45] European countries with the US were the first to establish industrial wind farms, and they were the first facing the decommissioning issues after 20 years. Each state reacted promptly, putting in place partial regulations to ensure that the operation would not surprise too much.

Dismantling the metal parts did not cause special issues as all industrial countries possess the technology and industrial means for recycling. However, it was not the same with the concrete foundation and the blades. The high volume of concrete to dismantle and the cost of this operation surprised the operators that proposed alternatives to the public authorities. For example, Denmark recommends removing one meter below ground regarding the dismantling of the wind turbine foundations when France specifies different scenarios by derogation, suggesting removing 40 centimeters in agriculture areas, two meters in the forest, and one meter for other lands. Some other countries like Spain include the decommissioning conditions into the Environment Impact Assessment (EIA) when Italy requires the complete removal of the installation and return the land to its original status.[46]

However, the decommissioning of wind turbine blades manufactured in carbon fiber-based composite was more challenging. Most countries adopted to cut and bury them, but it could not be sustainable waste management. Different searchers are working on various technologies that would enable an acceptable recycling method for composite blades. The exercise was more complicated to set up an appropriate waste management regulation for those blades, and the situation still needs to improve. Besides, the Germany Institute of Standardization can serve as an example by publishing the First Standard for dismantling and recycling wind turbines, the DIN SPEC 4866.[47]

Role of the international organizations in setting up wind turbine dismantling international standards

Faced with the absence of international standards to regulate the dismantling of wind turbines, WindEurope has taken the lead and proposed a text which should lead to international regulations to the International Electrotechnical Commission (IEC) for wind turbines, to create an amendment to 61400-28 CD.[48] The said document limits its extend to fixing standard payment schemes in wind power development and how this might be affected by introducing a free electricity market. Indeed, in a 53 Pages document, Wind Europe reviews different  European countries and European rules to set up a unique standard for Europe that can serve the rest of the world. However, the proposal still an industry guidance document for onshore wind turbines only. It will require extending the circle of participants to develop an international regulation considering the specificities of the states more invested in wind energy development.

As the world sees wind power increasing, we shall also think about more wind turbines that will end their lives and require decommissioning. The regulations shall consider all materials that constitute the wind turbine, the landscape, and the general environmental impact. Additionally to the metal mast, copper of the generator, and cables usually recycled at more than 98%, the standard shall regulate the disposal of the concrete foundation extends to the recommended recycling method of the quantities removed from the foundation block, keeping the respect of the existing regulations. It shall include the disposal of rare-earth: Even if rare-earth is in small amounts, their extraction from mines justifies a close follow-up, and if possible, a recommendation for recycle. Besides, the standard must dedicate special attention to the disposal of the carbon fiber-based composite of the blades, encouraging recycling methods that do not generate more CO2 during the operation.

Furthermore, the standard shall reserve special attention to the disposal of oil used to cool the generator and lubrication of all rotating parts. For offshore wind turbines, the standards must consider the risk of marine pollution by dumping wastes for offshore wind turbines. Regarding the environmental impacts, the absence of dedicated maritime regulations may lead to decisions that can harmfully disturb the marine environment. As a result, the IRENA has in its mandate the role to lead the elaboration of specific regulations and guidelines that include precise liabilities for the owners.

Conclusion

For some time, European countries and the US started dismantling old wind parks before reaching their lifespan. As the technology in this field has evolved considerably, repowering, which consists of replacing old machines with more powerful and more productive turbines, is profitable. Still, above all, it makes it possible to produce more renewable energy. The first wind turbines installed in Europe and the United States at the end of the previous century were, for the most part, with less than one megawatt, while that of onshore turbines built today is often greater than 3MW. Thus, using the same mast, it is possible to double or triple the wind system capacity. Another advantage: the maintenance costs of current wind turbines are seriously lower. As we can see, in this area, as in many others, technological developments in recent decades have been meteoric.

Alongside repowering, extending the life of wind turbines is an attractive alternative for wind farm operators. An extension of one to five years would not pose any significant technical problem because manufacturers often base themselves on meteorological assumptions much more restrictive than the actual conditions to calculate the theoretical lifespan of their products. Extending machine life is an ideal solution when repowering is not an option. After studying the past life of the wind turbine and its degree of fatigue (maintenance history, broken parts, etc.), inspections can help calculate the residual time of the machines and the interventions necessary to allow this extension (replacement of particular parts, repairs, etc.).

It appears that the wind turbine end-of-life problem is much less severe than it first appears. Outright dismantling would be detrimental to electricity operators who would find themselves without part of their installed power, not to mention the cost of dismantling operation. Fortunately, there is repowering which allows them to extend their lifespan. However, governments and international renewable energy agencies should ensure that adequate procedures are in place on the conditions for repowering or extending the life of turbines for the safety of people. Some countries started thinking about formal regulations and standards of the dismantling process. Indeed, it is necessary, for example, to check the resistance of the foundations repowered with a higher mast and more extended and heavier blades. International organizations in partnership with IRENA should play a significant role in preparing and advocating for global standard regulation of the decommissioning, repowering, dismantling, and recycling wind turbines worldwide.

Conflict of Interest

I, Ladislas HAVUGIMANA, declare that no conflict of interest has guided or has influenced the research conducted for this article.

Acknowledgment

I acknowledge the contribution of Euclid University through different energy courses, and I especially thank Pr Laurent Cleenewerck for his guidance for the research toward the completion of this article.

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[23] Mishnaevsky, Jr., Leon. Sustainable End-of-Life Management of Wind Turbine Blades: Overview of Current and Coming Solutions, 2021.

[24] Mishnaevsky Jr, Leon, Kim Branner, Helga Nørgaard Petersen, Justine Beauson, Malcolm McGugan, and Bent F. Sørensen. Materials for Wind Turbine Blades: An Overview, 2017.

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[26] Rademakers, L.W.M.M., H. Braam, and T.S. Obdam. Estimating Costs of Operation & Maintenance for Offshore Wind Farms, 2008.

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[28] Robert, Wilson. “Can You Make a Wind Turbine Without Fossil Fuels?” Energy Central. Last modified July 7, 2018. Accessed June 14, 2021.

https://energycentral.com/c/ec/can-you-make-wind-turbine-without-fossil-fuels.

[29] Sadagopan, Madumita. “Study on Recycling of Concrete in Sweden” (2018): 17.

[30] Schipani, Vanessa. “Wind Energy’s Carbon Footprint.” FactCheck.Org, March 14, 2018. Accessed June 16, 2021. https://www.factcheck.org/2018/03/wind-energys-carbon-footprint/.

[31] Shen, Yuzhou, Ruthann Moomy, and Roderick G. Eggert. “China’s Public Policies toward Rare Earths, 1975–2018.” Mineral Economics 33, no. 1–2 (July 2020): 127–151.

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[34] Welstead, J., R. Hirst, D. Keogh, G. Robb, and R. Bainsfair. “Research and Guidance on Restoration and Decommissioning of Onshore Wind Farms” (2013): 112.

[35] WindEurope. Decommissioning of Onshore Wind Turbines – Industry Guidance Document, 2020.

[36] WindEurope. “Wind Industry Calls for Europe-Wide Ban on Landfilling Turbine Blades.” WindEurope. Last modified June 16, 2021. Accessed June 23, 2021. https://windeurope.org/newsroom/press-releases/wind-industry-calls-for-europe-wide-ban-on-landfilling-turbine-blades/.

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[1] Michael Brunn, “Joint Project to Advance Wind Turbine Recycling,” Recycling Magazine, July 3, 2019, 1, accessed July 5, 2021, https://www.recycling-magazine.com/2019/07/03/joint-project-to-advance-wind-turbine-recycling/.

[2] IRENA, “Nurturing Offshore Wind Markets: Good Practices for International Standardisation” (2018): 13.

[3] IRENA, “30 Years of Policies for Wind Energy: Lessons from 12 Markets (2013 Edition),” 31, last modified 2013, accessed June 13, 2021, https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2013/GWEC_WindReport_All_web-display.pdf.

[4] GWEC, “Global Wind Annual Report 2021,” 44, last modified 2021, accessed June 13, 2021, https://gwec.net/wp-content/uploads/2021/03/GWEC-Global-Wind-Report-2021.pdf.

[5] IRENA, “Future of Wind 2019,” 29, last modified 2019, accessed June 13, 2021, https://irena.org/-/media/Files/IRENA/Agency/%20Publication/2019/Oct/IRENA_Future_of_wind_2019.pdf.

[6] Paul Gipe, Wind Energy for the Rest of Us_ A Comprehensive Guide to Wind Power and How to Use It, 2016, 661.

[7] WindEurope, “Wind Industry Calls for Europe-Wide Ban on Landfilling Turbine Blades,” WindEurope, 1–2, last modified June 16, 2021, accessed June 23, 2021, https://windeurope.org/newsroom/press-releases/wind-industry-calls-for-europe-wide-ban-on-landfilling-turbine-blades/.

[8] Wilson Robert, “Can You Make a Wind Turbine Without Fossil Fuels?,” Energy Central, 1–5, last modified July 7, 2018, accessed June 14, 2021, https://energycentral.com/c/ec/can-you-make-wind-turbine-without-fossil-fuels.

[9] IRENA, Renewable energy technologies: Cost analysis series. Volume 1: Power Sector, Issue 5/5, Wind Power, 2012, 18–19, https://www.irena.org/publications/2012/Jun/Renewable-Energy-Cost-Analysis—Wind-Power.

[10] IRENA, “Future of Wind 2019,” 13.

[11] Søren Krohn, Poul-Erik Morthorst, and Shimon Awerbuch, “The Economics of Wind Energy” (March 2009): 3.

[12] IRENA, Renewable energy technologies: Cost analysis series. Volume 1: Power Sector, Issue 5/5, Wind Power, 42–44.

[13] Rademakers et al., Estimating Costs of Operation & Maintenance for Offshore Wind Farms, 2008, 3.

[14] IRENA, Renewable energy technologies: Cost analysis series. Volume 1: Power Sector, Issue 5/5, Wind Power, 50.

[15] EIS-PCC, “European Insurance Solution PCC,” 2011, 1, accessed June 24, 2021, http://www.eis-pcc.com/our-services/wind-energy-decommissioning/.

[16] Rick Kelley, “Retiring Worn-out Wind Turbines Could Cost Billions That Nobody Has,” Energy Central, 4, last modified February 20, 2017, accessed June 14, 2021, https://energycentral.com/news/retiring-worn-out-wind-turbines-could-cost-billions-nobody-has.

[17] GHD, “Cassadaga Wind Farm – Decommissionning Cost Estimate,” 7, last modified July 11, 2017, accessed June 26, 2021, http://www.charlotteny.org/pdfs/2018/wind/11110309-RPT1%20FINAL%20%207-11-2017.pdf.

[18] Ibid., 3–4.

[19] Welstead et al., “Research and Guidance on Restoration and Decommissioning of Onshore Wind Farms” (2013): 66.

[20] John Fialka, “New Wind Turbine Blades Could Be Recycled Instead of Landfilled,” Scientific American, 1, last modified November 27, 2020, accessed June 20, 2021, https://www.scientificamerican.com/article/new-wind-turbine-blades-could-be-recycled-instead-of-landfilled/.

[21] Imholte et al., “An Assessment of U.S. Rare Earth Availability for Supporting U.S. Wind Energy Growth Targets,” Energy Policy 113 (February 2018): 12.

[22] Shen et al., “China’s Public Policies toward Rare Earths, 1975–2018,” Mineral Economics 33, no. 1–2 (July 2020): 131.

[23] GWEC, “Global Wind Annual Report 2021,” 11.

[24] Stena Metall, Focus on Recycling of Rare Earth Metals within EU, 2016, 1, accessed June 20, 2021, https://www.youtube.com/watch?v=DUAxBCtvHB8&t=77s.

[25] Kiran Tota-Maharaj and Alexander McMahon, “Resource and Waste Quantification Scenarios for Wind Turbine Decommissioning in the United Kingdom,” Waste Disposal & Sustainable Energy (December 16, 2020): 12, accessed June 22, 2021, http://link.springer.com/10.1007/s42768-020-00057-6.

[26] Madumita Sadagopan, “Study on Recycling of Concrete in Sweden” (2018): 2–3.

[27] Welstead et al., “Research and Guidance on Restoration and Decommissioning of Onshore Wind Farms,” 53.

[28] Mishnaevsky et al., Materials for Wind Turbine Blades: An Overview, 2017, 5–6.

[29] Karen Wood, “Wind Turbine Blades: Glass vs. Carbon Fiber,” 2, last modified May 31, 2012, accessed June 24, 2021, https://www.compositesworld.com/articles/wind-turbine-blades-glass-vs-carbon-fiber.

[30] Brandon Ennis et al., “Optimized Carbon Fiber for Wind Energy; Project and Market Overview,” 5, last modified 2017, accessed June 24, 2021, https://www.osti.gov/servlets/purl/1483209.

[31] Leon Mishnaevsky, Sustainable End-of-Life Management of Wind Turbine Blades: Overview of Current and Coming Solutions, 2021, 8.

[32] Behzad Rahnama, “Reduction of Environmental Impact Effect of Disposing Wind Turbine Blades” (2011): 7.

[33] Evan Milberg, “Global Fiberglass Solutions Finds Success Recycling Turbine Blades,” 1, last modified November 6, 2017, accessed June 17, 2021, http://compositesmanufacturingmagazine.com/2017/11/global-fiberglass-solutions-finds-success-recycling-turbine-blades/.

[34] Lantz et al., Wind Power Project Repowering: Financial Feasibility, Decision Drivers, and Supply Chain Effects, December 1, 2013, 10, accessed June 24, 2021, http://www.osti.gov/servlets/purl/1117058/.

[35] Gipe, Wind Energy for the Rest of Us_ A Comprehensive Guide to Wind Power and How to Use It, 590.

[36] Ibid., 770.

[37] IRENA, “Future of Wind 2019,” 29.

[38] Welstead et al., “Research and Guidance on Restoration and Decommissioning of Onshore Wind Farms,” 45.

[39] Ibid., 31.

[40] NREL, “Tall Towers Tap Greater Wind Resource Potential,” 1, last modified July 11, 2019, accessed June 24, 2021, https://www.nrel.gov/news/program/2019/tall-towers-tap-greater-wind-resource-potential.html.

[41] Vanessa Schipani, “Wind Energy’s Carbon Footprint,” FactCheck.Org, March 14, 2018, 1–5, accessed June 16, 2021, https://www.factcheck.org/2018/03/wind-energys-carbon-footprint/.

[42] GWEC, “Jobs-Note-April-2021-2.Pdf,” 5, last modified April 2021, accessed June 18, 2021, https://gwec.net/wp-content/uploads/2021/04/Jobs-Note-April-2021-2.pdf.

[43] Gülşen Çağatay, “Offshore Wind Sector to Create Nearly 1 Million Jobs in 5 Years,” Daily Sabah, 1, last modified August 17, 2020, accessed June 24, 2021, https://www.dailysabah.com/business/energy/offshore-wind-sector-to-create-nearly-1-million-jobs-in-5-years.

[44] IRENA, “Renewable Energy and Jobs – Annual Review 2020” (2020): 3.

[45] GWEC, “The World Is on Course for 800 GW of Wind Energy Capacity by 2021,” Global Wind Energy Council, May 5, 2017, 1, accessed July 5, 2021, https://gwec.net/the-world-is-on-course-for-800-gw-of-wind-energy-capacity-by-2021/.

[46] WindEurope, Decommissioning of Onshore Wind Turbines – Industry Guidance Document, 2020, 15.

[47] Michael Brunn, “First Standard for Dismantling and Recycling of Wind Turbines.,” Recycling Magazine, July 23, 2020, 1–2, accessed June 24, 2021, https://www.recycling-magazine.com/2020/07/23/first-standard-for-dismantling-and-recycling-of-wind-turbines/.

[48] Larsen et al., “Contributions from the Department of Wind Energy and Atmospheric Physics to EWEC’99 in Nice, France,” 7, last modified March 1999, accessed July 10, 2021, https://www.osti.gov/etdeweb/servlets/purl/679626.