Wind turbine blade manufacturing

Abstract

A wind turbine blade is disclosed. A wind turbine blade includes a core material, a first fiber reinforced plastic and a spar cap including a third fiber reinforced plastic, and a shear web including a second fiber reinforced plastic. The first fiber reinforced plastic, the second fiber reinforced plastic, and the spar cap each include a chemically detachable polymer. Also disclosed is a method of disassembling such a wind turbine blade, the method comprising: exposing the wind turbine blade to an acid to disassemble the chemically detachable polymer; and recovering fibers from at least one of the first fiber-reinforced plastic, the second fiber-reinforced plastic, and the third fiber-reinforced plastic.

Description

Technical Field

[0001] The present invention generally relates to wind turbine blades and methods for recovering wind turbine blades. Background Art

[0002] Composite wind turbine blades comprise multiple components that are differently configured to withstand the loads and conditions experienced by the blades during extended use in extreme conditions, while being subject to space, weight, and shape constraints to provide an aerodynamically efficient shape. The use of composite materials in the manufacture of such components is often advantageous because the arrangement of the materials used can be highly optimized based on the specific requirements of each component. However, this can result in blades with a complex bill of materials, including several types of fiber-reinforced plastics, foam core materials, and resin systems, with a limited overall recycling strategy, as each component may require different treatment at the end of its life for full recycling.

[0003] Furthermore, the nature of composite wind turbine blade construction is such that once the bonding resins and adhesives have cured, the components and materials cannot be easily separated mechanically or chemically. Therefore, it is difficult to extract materials for recycling from blades that have reached the end of their life.

[0004] It is against this background that the present invention has been devised. Summary of the Invention

[0005] A first aspect of the present invention provides a wind turbine as disclosed in claim 1. The wind turbine blade comprises a blade shell comprising a core material, a first fiber-reinforced plastic, a spar cap comprising a third fiber-reinforced plastic, and a shear web comprising a second fiber-reinforced plastic. The first fiber-reinforced plastic, the second fiber-reinforced plastic, and the third fiber-reinforced plastic each comprise a chemically disassemblable polymer. The shear web is connected to the blade shell, for example, by an adhesive or by infusion resin during resin infusion to form the first fiber-reinforced plastic. This has been found to be highly advantageous because it allows for chemical disassembly of several components of the wind turbine blade simultaneously and / or under the same conditions without first having to separate the components from one another. Furthermore, this allows for easier separation of components that do not contain a chemically disassembly polymer from components that contain a chemically disassembly polymer by first chemically disassembling one or more chemically disassembly polymers and thereafter separating components that do not contain the chemically disassembly polymer from the disassembled components. In addition, some components comprising chemically detachable polymers also contain elements which are not chemically detachable polymers, such as fibers, sensors, metal parts, and these can also be easily removed after chemical detachment of the chemically detachable polymer. By chemically detachable polymers is meant herein a thermosetting polymer which can be detached in acid by chemical cleavage of bonds in the polymer backbone. A chemically detachable polymer can be, for example, a polymer with a cleavable crosslinker, such as exemplified in WO2018 / 050189A1. Other examples of soluble polymers are based on the inventions produced by Aditya Birla Group under the trademark Resin systems for sale and from Arkema Polymers of polymer systems.

[0006] Optionally, the chemically disassembled polymer of each of the first fiber-reinforced plastic, the second fiber-reinforced plastic, and the third fiber-reinforced plastic is based on the same polymer system. This allows for a simple process in which a large portion of a wind turbine blade can be processed simultaneously, rather than carefully separating the blade into individual components prior to recycling involving chemical disassembly of the blade.

[0007] Currently, wind turbine blade recycling has focused on the recycling of fiber-reinforced plastic components, primarily for the extraction of fibers for reuse. In some embodiments of the present invention, blades are designed so that both fiber-reinforced plastic components and polymer components without reusable fiber reinforcements (such as adhesives, coatings, and / or foams) can be recycled using a common strategy, which allows for greater efficiency in the recycling process and the potential for simultaneous chemical disassembly of several components of the blade. This saves time and improves overall recycling rates because, for example, wasteful separation of components prior to their individual recycling can be avoided.

[0008] A wind turbine blade may include an adhesive. The adhesive may be used, for example, to bond a shear web to a blade shell, a sensor to a blade, a blade root to a blade, and / or a leading edge protection shell to a blade. The adhesive may include a chemically degradable polymer. The chemically degradable polymer of the adhesive is preferably based on the same polymer system as the chemically degradable polymer of each of the first fiber-reinforced plastic, the second fiber-reinforced plastic, and the third fiber-reinforced plastic. In another embodiment, the adhesive is based on another polymer system than the chemically degradable polymer of at least the first fiber-reinforced plastic and the second fiber-reinforced plastic.

[0009] In one embodiment, the wind turbine blade further comprises at least one wind turbine blade coating disposed on the blade shell, wherein the blade coating further comprises a chemically decomposable polymer. Preferably, the chemically decomposable polymer of the wind turbine blade coating is based on the same polymer system as the chemically decomposable polymer of each of the first fiber-reinforced plastic, the second fiber-reinforced plastic, and the third fiber-reinforced plastic. This has been found to allow for a system in which the coating chemically dissolves with other components and thus does not delay or prevent chemical decomposition of other parts of the blade. Furthermore, this increases the total amount of recycled material from the blade.

[0010] The core can be a lightweight, dimensionally stable material, such as a balsa wood core or a polymer foam core. In one embodiment, the core is a thermoplastic foam core material, and preferably a material of a polymer system that cannot be chemically disassembled. Therefore, the foam core can be easily separated from the components comprising the chemically disassembled polymer after these components have been partially or completely chemically disassembled. This will also be the case if the core is based on balsa wood, for example. In another embodiment, the core material is a foam core and comprises a chemically disassembled polymer, and preferably, the chemically disassembled polymer of the foam core material is based on the same polymer system as the chemically disassembled polymer of each of the first fiber reinforced plastic, the second fiber reinforced plastic and the third fiber reinforced plastic. In this embodiment, the foam core can be chemically disassembled together with the other components comprising the chemically disassembled polymer, so that there is no need to mechanically separate the components before chemical disassembly.

[0011] A wind turbine blade may include a putty, also known as a filler, for adjusting the aerodynamic profile of the wind turbine blade and filling gaps. The putty may include a chemically decomposable polymer, and preferably, the chemically decomposable polymer of the putty is based on the same polymer system as the chemically decomposable polymer of each of the first fiber-reinforced plastic, the second fiber-reinforced plastic, and the third fiber-reinforced plastic. In this embodiment, the putty can be chemically decomposable along with other components including the chemically decomposable polymer, thus eliminating the need to mechanically separate the components prior to chemical decomposition.

[0012] In one embodiment, the properties of the first component are different from the properties of the second component, wherein the first component and the second component are different components selected from the group consisting of a first fiber reinforced plastic, a second fiber reinforced plastic, and a third fiber reinforced plastic. If one or more of the adhesive, the coating, and the core include a chemically decomposable polymer, it is preferred that the group also include a chemically decomposable polymer of the components of the list. Preferably, the different properties are at least two properties selected from the group consisting of tensile strength, compressive strength, flexural strength, hardness, Young's modulus, transparency, abrasion resistance, surface gloss, and density. For example, for the first fiber reinforced plastic and the second fiber reinforced plastic, it is preferred that, in contrast to the adhesive, the chemically decomposable polymer is transparent to allow visual quality assurance of the presence of wetting and / or pores in the cured fiber reinforced plastic, while the adhesive is preferably opaque and more preferably dyed with a bright color (such as green, blue, red, or yellow) to facilitate visual inspection of the presence of the adhesive in key locations. For the core material, it is preferred that the density is much lower than that of the other components, and the density of the core material is typically less than 50% of that of the other components. For the coating, it is preferred that the wear resistance measured in the accelerated rain erosion test is higher than that of other components and / or the surface gloss is higher than that of other components.

[0013] In one embodiment, the chemically decomposable polymer of the first component has properties that differ from the chemically decomposable polymer of the second component, wherein the first and second components are different components selected from the group consisting of a first fiber-reinforced plastic, a second fiber-reinforced plastic, and a third fiber-reinforced plastic. If one or more of the coating, core, and adhesive comprises a chemically decomposable polymer, it is preferred that the group also comprise chemically decomposable polymers from the group consisting of components from that list. Preferably, the different properties are at least two properties selected from the group consisting of glass transition temperature, tensile strength, compressive strength, flexural strength, hardness, Young's modulus, transparency, and density. Generally, the glass transition temperature is preferably above 70°C, but for the coating, it is preferably higher, such as above 80°C or above 90°C. For the first and second fiber-reinforced plastics, in contrast to the adhesive, the chemically decomposable polymer is preferably transparent to allow for visual quality assurance of wetting and lack of porosity in the cured fiber-reinforced plastics, while the adhesive is preferably opaque and more preferably dyed in a bright color (such as green, blue, red, or yellow) to facilitate visual inspection of the presence of adhesive in critical locations. For the core material, it is preferred that the compressive strength and shear strength of the chemically decomposable polymer be higher than those of the other component.

[0014] In another embodiment, the uncured chemically decomposable polymer resin of the first component is different from the uncured chemically decomposable polymer of the second component, wherein the first component and the second component are different components selected from the group consisting of the first fiber reinforced plastic, the second fiber reinforced plastic and the third fiber reinforced plastic. If one or more of the coating, the core and the adhesive include a chemically decomposable polymer, it is preferred that the group also include a chemically decomposable polymer of the components of the list. Preferably, the different characteristics are at least two characteristics selected from the group consisting of transparency, color, viscosity, pot life and curing time. For the uncured chemically decomposable polymer resin of the first fiber reinforced plastic and the second fiber reinforced plastic, it is preferred to have a high pot life and low viscosity to allow complete infusion before the resin is cured. The adhesive is preferably opaque and more preferably dyed with a bright color (such as green, blue, red or yellow) to facilitate visual inspection of the adhesive at key locations before the resin is cured. If present, the chemically decomposable polymer resin of the foam material preferably has a high ability (such as high viscosity and surface energy) to maintain bubbles, a low curing time and a low curing temperature. If present, the chemically disintegrable polymer resin in the spar and / or spar cap may preferably be provided via pultrusion of glass or carbon fibres, where rapid curing is preferred to allow for rapid processing speeds.

[0015] In another embodiment, the chemically decomposable polymers of each of the first fiber-reinforced plastic, the second fiber-reinforced plastic, the third fiber-reinforced plastic, and the foam core material can be chemically decomposed under the same process conditions. The process conditions can be, for example, one or more of temperature, time, pressure, the fluid in which the process is performed, the concentration of substances in the fluid, and the presence of active ingredients (such as catalysts) in the fluid. This allows the chemically decomposable polymers of these components to be chemically decomposed simultaneously, and then other parts of these components, such as fibers, metal inserts, sensors, and other polymer parts, can be easily separated after or during the chemical decomposition process.

[0016] In another embodiment, the chemically decomposable polymer of the first component and the chemically decomposable polymer of the second component can be chemically decomposable under a first set of process conditions, wherein the chemical decomposition of the first component under the first set of process conditions is faster than the chemical decomposition of the second component under the first set of process conditions. This allows for the sequential decomposition of wind turbine blades. For example, the second component may include carbon fibers and the first component may include glass fibers, whereby the gradual chemical decomposition of the polymers allows the separation of the glass fibers before proceeding to the complete chemical decomposition of the component including the carbon fibers, thereby allowing the production of two separate fractions of fibers—one comprising solely or primarily glass fibers and one comprising solely or primarily carbon fibers. Such separated fractions allow for reuse in higher-value applications compared to fractions containing a large proportion of both glass and carbon fibers.

[0017] In another embodiment, the chemically disassembled polymer of the first component can be chemically disassembled under a first set of process conditions, and the chemically disassembled polymer of the second component does not chemically disassemble under the first set of process conditions. For example, the first component can be chemically disassembled under process conditions that do not require a catalyst, such as at elevated temperature, pressure, and / or under mild acidic conditions, while the second component can require the presence of a catalyst (e.g., an organometallic complex), more acidic conditions, and / or the presence of an additional organic co-solvent to undergo the chemical disassembly process. This allows for sequential disassembly with separation steps between the disassembly steps.

[0018] Optionally, the wind turbine blade further comprises a leading edge protector arranged on at least a portion of the leading edge of the blade, wherein at least a portion of the leading edge protector and / or a leading edge adhesive bonding the leading edge protector to the blade comprises a chemically degradable polymer.

[0019] Optionally, each of the decomposable polymers may optionally be decomposable under the same process conditions.

[0020] A second aspect of the invention provides a method of disassembling a wind turbine blade according to claim 11 .

[0021] A second aspect of the present invention provides a method for disassembling a wind turbine blade. The method comprises the steps of exposing the wind turbine blade to an acid to disassemble the chemically disassemblyable polymer; and recovering fiber from at least one of the first fiber reinforced plastic, the second fiber reinforced plastic, and the third fiber reinforced plastic. Preferably, the acid comprises formic acid, as formic acid has been found to provide relatively rapid chemical disassembly at lower temperatures than most other acids and / or chemical disassembly within a practical timeframe. Furthermore, formic acid is a readily available bulk chemical that can be derived from recyclable sources and has a limited chemical risk profile. The method can, for example, recycle the recovered fiber and disassembled polymer for use in manufacturing new wind turbine blades or other products. This reduces the amount of virgin resources required for manufacturing and the carbon footprint of the wind turbine blade.

[0022] In one embodiment, the acid causes the chemically resolvable polymer to disassemble into at least one monomer and / or oligomer and / or cleave the polymer backbone, and the method further includes recovering the monomer and / or oligomer and / or polymer portion, for example by treating the chemically resolvable polymer with a base. The recovered monomer can be reused in new products, such as resins for wind turbine blades. The oligomer can be reused in new resin or further decomposed into monomers before reuse in, for example, a new resin.

[0023] In one embodiment, the method includes recovering non-fibrous material from a wind turbine blade, wherein the non-fibrous material optionally includes metal, wood, undisassembled polymer, and / or partially disassembled polymer. The undisassembled polymer may be, for example, a thermoplastic-based core material or a component of a non-disassembled thermoset resin, such as a coating or a thermoset composite material.

[0024] In one embodiment, the wind turbine blades are broken into blocks before exposure to the acid. This has been found to facilitate processing of the blocks and may involve removing components that are not affected by the chemical disassembly process and therefore will only increase the volume of the processed blocks and not be obtained from the process.

[0025] In one embodiment, the method further comprises removing the spar caps prior to exposure to the acid. It has been found that, in some cases, even if the spar is susceptible to chemical disassembly, mechanical separation of these components prior to chemical disassembly may allow for better separation of the (carbon) fibers of the spar caps from the (glass) fibers of the first fiber reinforced plastic and / or the second fiber reinforced plastic.

[0026] In one embodiment, the chemically decomposable polymer of the first component has properties that differ from the chemically decomposable polymer of the second component, wherein the first component and the second component are different components selected from the group consisting of a first fiber-reinforced plastic, a second fiber-reinforced plastic, and a third fiber-reinforced plastic. If one or more of the coating, the core, and the adhesive comprises a chemically decomposable polymer, it is preferred that the group also comprises chemically decomposable polymers of components from that group. Preferably, the differing properties are at least two properties selected from the group consisting of glass transition temperature, tensile strength, compressive strength, flexural strength, hardness, Young's modulus, transparency, and density. The chemically decomposable polymer of the first component and the chemically decomposable polymer of the second component are chemically decomposable under a first set of process conditions, wherein the chemical decomposition of the first component under the first set of process conditions is faster than the chemical decomposition of the second component under the first set of process conditions. In this embodiment, exposing the wind turbine blade to an acid to decompose the chemically decomposable polymer comprises the steps of first at least partially chemically decomposing the first component and the second component under the first set of process conditions, thereafter separating the second component from the first component, and thereafter decomposing the second component under a second set of process conditions. This process can be considered already during the manufacture of wind turbine blades and allows chemical disassembly-enhanced blade design separation, resulting in simpler handling and higher value recycled products.

[0027] In one embodiment, the chemically decomposable polymer of the first component has properties that differ from properties of the chemically decomposable polymer of the second component, wherein the first component and the second component are different components selected from the group consisting of a first fiber-reinforced plastic, a second fiber-reinforced plastic, and a third fiber-reinforced plastic. If one or more of the coating, the core, and the adhesive comprises a chemically decomposable polymer, it is preferred that the group also comprises chemically decomposable polymers of components comprising the group. Preferably, the different properties are at least two properties selected from the group consisting of glass transition temperature, tensile strength, compressive strength, flexural strength, hardness, Young's modulus, transparency, and density. The chemically decomposable polymer of the first component is chemically decomposable under a first set of process conditions, and the chemically decomposable polymer of the second component is not chemically decomposable under the first set of process conditions. In this embodiment, exposing the wind turbine blade to an acid to decompose the chemically decomposable polymer comprises the steps of first at least partially chemically decomposing the first component under the first set of process conditions, thereafter separating the second component from the first component, and thereafter decomposing the second component under a second set of process conditions. This process can be considered already during the manufacture of wind turbine blades and allows chemical disassembly-enhanced blade design separation, resulting in simpler handling and higher value recycled products.

[0028] In another aspect, the present invention provides a wind turbine comprising a plurality of wind turbine blades as described above mounted on a hub, wherein the hub is mounted on a nacelle supported by a tower.

[0029] In another aspect, the present invention provides a method for manufacturing a wind turbine blade, comprising: arranging a core material, a first fiber, and a spar cap of a third fiber-reinforced plastic in a blade mold, and infusing the first fiber with a resin; preparing a shear web from a second fiber and a resin to form a second fiber-reinforced plastic; and assembling the blade shell and the shear web using an adhesive, wherein the first fiber-reinforced plastic, the second fiber-reinforced plastic, and the third fiber-reinforced plastic comprise a chemically decomposable polymer. Alternatively, the blade can be manufactured using a single shot process, wherein the entire blade shell is infused simultaneously, and one or more shear webs are placed within the blade shell before or after infusion.

[0030] Optionally, the method comprises the step of using fibers recovered from a wind turbine blade as the first fiber and / or the second fiber in another method of the invention.

[0031] Optionally, the method comprises the step of using core material recovered from a wind turbine blade as core material in another method of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order that it may be more fully understood, the invention will now be described, by way of example only, with reference to the following drawings in which like features are assigned like reference numerals, and in which:

[0033] Figure 1 is a schematic perspective view of a wind turbine blade;

[0034] Figure 2 is a schematic cross-sectional view of a wind turbine blade;

[0035] Figure 3 A typical horizontal axis wind turbine is shown; and

[0036] Figure 4 A method of disassembling a wind turbine blade is shown. DETAILED DESCRIPTION

[0037] To provide context for the present invention, Figure 1 and Figure 2 The structure of an example wind turbine blade is shown. Figure 1 is a schematic perspective view of a wind turbine blade 10, Figure 2 is a schematic cross-sectional view of a wind turbine blade 10. Figure 1As seen, the blade 10 extends in a spanwise direction (spanwise) between a root end 12 and a tip end 14 , and in a chordwise direction (chordwise) between a leading edge 16 and a trailing edge 18 .

[0038] Blade 10 includes an aerodynamic outer shell 20 defining a substantially hollow interior 21 therein. Outer shell 20 may be formed from first and second shell halves 22a, 22b that are bonded together at or near leading and trailing edges 16, 18 with a polymer-based adhesive (not shown).

[0039] The outer shell 20 is a composite construction including a core material, such as a polymer-based foam core material 24, arranged in a sandwich configuration between an inner first fiber reinforced plastic (FRP) skin 23 and an outer first fiber reinforced plastic (FRP) skin 25. The inner skin 23 and the outer skin 24 include layers of fiber material, such as carbon fiber, glass fiber, and aramid fiber provided in a non-crimped fabric, chopped strand mat, or woven fabric. The outer shell 20 also includes a polymer matrix material that binds the core material 24 and the arrangement of fiber materials together to form a unitary structure.

[0040] The outer shell 20 may be reinforced to withstand the loads to which the blade 10 is subjected in use and to improve the structural rigidity of the blade. Figure 2 In the example shown, the first and second half shells 22a, 22b each include a longitudinally extending reinforcement structure known as a spar cap 30. The spar cap 30 typically comprises a third fiber reinforced plastic 32 comprising a third fiber reinforced material layer held in laminate form by a polymer matrix material. Figure 2 In the example shown, the spar caps 30 are embedded within the outer shell 20. However, in other examples, they may be bonded to the inner skin 23 of the shell 20 using a polymer-based adhesive, such as the additional adhesive 38.

[0041] The outer shell 20 may optionally include a leading edge protector (not shown) attached to the leading edge 16 of the blade 10 to protect the leading edge 16 of the blade 10 during use. The leading edge protector may comprise another FRP material comprising a layer of fiber-reinforced material held in a laminated form by a polymer matrix material. Alternatively, the leading edge protector may comprise only a polymer-based material or coating. The leading edge protector may be bonded to the blade using a leading edge adhesive.

[0042] The outer shell 20 may also include a coating applied to its outer skin 24 for protecting the shell structure 20 from exposure to environmental conditions when the blade 10 is in use. The coating may be a polymer-based gelcoat or paint.

[0043] like Figure 1 and Figure 2As shown, the blade 10 also includes a shear web 35 that extends longitudinally in the span direction within the outer shell 20 (i.e., inside the hollow interior 21 of the blade 10). In some examples, the wind turbine blade 10 may include multiple shear webs 35, such as a trailing edge shear web and a main shear web. Each shear web 35 forms part of a spar structure that is configured to absorb bending and torsional loads of the blade 10 during use. Figure 2 As shown, an upper web flange 36 of a shear web 35 is connected to the inner skin 23 of the first shell half 22a, and a lower web flange 37 is connected to the inner skin 23 of the second shell half 22b. The shear web 35 is bonded to the shell 20 by an additional polymer-based adhesive 38 located between the upper and lower web flanges 36, 37 and the respective inner skin 23 of the shell 20. The shear web 35 comprises a second fiber-reinforced plastic material 39 comprising a second fiber-reinforced material layer held in laminated form by a polymer matrix material.

[0044] The several components that make up blade 10 include one or more polymer-based materials in the form of a matrix material, coatings, adhesives, or foams. Polymer-based materials can be thermosets or thermoplastics, but for wind turbine blades, polymer-based materials are typically thermosets.

[0045] In the example shown here, each of the polymer-based materials used to manufacture blade 10 is configured to be chemically disassembled by exposure to an acid, such as acetic acid or formic acid. For example, each polymer-based material can be configured to disassemble into monomers and / or oligomers and / or cleave the polymer backbone when exposed to acetic acid at a concentration between 20% and 50% in water. In this manner, one or more polymer-based materials can be disassembled by any combination of softening, swelling, disintegration, and / or dissolution, thereby allowing the fiber reinforcement material to be released from the various components comprising blade 10 and recovered for recycling.

[0046] Recently developed epoxy resin systems that are configured to chemically disassemble under certain processing conditions can be used to form various polymer-based components of the wind turbine blade 10 described above. Examples include, but are not limited to, Epoxy from the Aditya Birla Group. Polymer systems and products from Arkema Polymer system.

[0047] The polymer systems of the various polymer-based materials forming the blade 10 are preferably selected to minimize the number of different disassembly steps required. This can be achieved by forming the various polymer-based components of the blade 10 from different polymer systems that are disassembled under the same or similar process conditions. However, preferably, all polymer-based materials forming the blade 10 are based on the same polymer system, so that a single set of process conditions can be used to disassemble the polymer-based materials of the blade 10 to allow for recovery and recycling of the fiber reinforcement material as well as the polymer material itself (depending on the polymer system).

[0048] In an alternative example, the various polymer-based components that form blade 10 can be based on two or more different polymer systems, each polymer system requiring a specific set of process conditions for chemical disassembly. For example, polymer-based additional adhesive 38 and any other polymer-based adhesives used to form blade 10 (such as the adhesive that joins first shell half 22a to second shell half 22b) can be based on a first polymer system that requires a first set of disassembly process conditions, while some or all other polymer-based components of blade 10 are based on a second polymer system that requires a second set of disassembly process conditions. The first set of process conditions can cause the polymer-based material based on the first polymer system to disassemble at a faster rate than the second set of process conditions cause the polymer-based material based on the second polymer system to chemically disassemble. Alternatively, both sets of process conditions can cause the polymer-based materials to disassemble at the same rate.

[0049] In the above example, the bonded components of the blade can be first separated by subjecting the blade to a first set of process conditions, and once separated, the remaining blade components can be processed under a second set of process conditions. This method can also be used, for example, to allow the fiber material of the outer shell 20 to be released and recovered separately from the fiber material of the shear web 35. This advantageously alleviates the need for a secondary fiber sorting process, where the fiber composition of the outer shell 20 is different from the fiber composition of the shear web 35.

[0050] The polymer-based materials based on the second polymer system may be largely unaffected by the first set of process conditions, or the disassembly of these polymer-based materials may begin during exposure to the first set of process conditions. For example, the polymer-based materials based on the second polymer system may soften during exposure to the first set of process conditions. This may be beneficial, for example, to allow components made from the second polymer system to be broken into smaller pieces for faster processing during exposure to the second set of process conditions.

[0051] It should be understood that the above discussion provides examples only, and that any number of polymer systems having any number of required sets of disassembly process conditions may be used to manufacture the various components of the blade 10 .

[0052] In all of the examples discussed above, the temperature of the acid solution can be increased to accelerate the rate of chemical disassembly. For example, the acid solution can be at a temperature between 60°C and 90°C.

[0053] Figure 3 A wind turbine 1 comprising a plurality of wind turbine blades 10 is shown. Figure 3 The wind turbine 1 shown in FIG. 1 is a representation of a typical horizontal axis wind turbine (HAWT) comprising a tower 2, a nacelle 3 mounted at the apex of the tower 2, and a rotor hub 4 supported on the nacelle 3. Three wind turbine blades 10 are supported by the rotor hub 4.

[0054] Now go to Figure 4 , shows a method of disassembling a wind turbine blade 10 constructed as described above. In this example, all polymer-based components of the blade 10 are based on the same polymer system.

[0055] In a first step, the blade 10 is mechanically divided into smaller blade sections 50, for example by sawing or crushing. The blade sections 50 are then exposed to an acid solution 42, such as by immersing or spraying the blade sections 50 with a water-based solution having a concentration of, for example, 40% acetic acid in water. The acid solution 42 is heated to a temperature of 85° C. before the blade sections 50 are immersed in the solution 42, and the temperature of 85° C. is maintained for the duration of the disassembly process. Other temperatures are also possible and are a compromise between evaporation, heating, and process time.

[0056] Exposure of the blade portion 50 to the acid solution 54 results in chemical decomposition of the polymer-based material, thereby converting the chemically decomposable polymers of the blade 10 into monomers and / or oligomers and / or polymeric portions, while leaving the fiber reinforcement and other chemically non-decomposable components of the outer shell, spar caps, and shear webs intact. The chemical decomposition of the polymer structure causes the polymer-based material to soften, swell, decompose, and / or dissolve in the acid, thereby releasing the fiber reinforcement and other non-decomposable elements.

[0057] Typical process times for treating the blade 10 to allow for the release of the fiber reinforcement range from 10 minutes to several days or even weeks, depending on the process conditions and polymer system in question. Once the polymer-based material has been sufficiently disassembled, the fiber reinforcement is recovered from the bath 52 by, for example, filtering the mixture of acetic acid and the disassembled polymer material. The fiber reinforcement can then be cleaned and reused as a recycled dry fiber material 55. In one example, the dry fiber material 55 can be chopped and used to produce a chopped strand mat of randomly oriented chopped fibers. If the FRP material includes multiple fiber types, an additional fiber sorting step may be required if stepwise dissolution has not already been used.

[0058] After the fiber reinforcement 55 is removed from the bath 52, the decomposed polymer material 56 can be extracted from the acid solution 54 using appropriate separation techniques. The recovered decomposed polymer material 57 can be recycled using known techniques, and the remaining acetic acid 54 can be reused in further disassembly of wind turbine blades.

[0059] Any metal or other non-polymer material (such as wood) may also be recovered from the bath 52. In an alternative example, any mechanically removable metal (or other material) portion may be removed from the blade 10 before the blade 10 is exposed to the acid solution 54. In another alternative example, the spar, spar cap 30, and / or shear web 35 may be removed from the blade 10 before the blade shell 20 is exposed to the acid solution 54.

[0060] It will be appreciated by those skilled in the art that modifications may be made to the specific embodiments described above without departing from the inventive concept defined by the claims.

Claims

1. A wind turbine blade comprising: a blade shell comprising a core material, a first fiber reinforced plastic and a spar cap comprising a third fiber reinforced plastic, and a shear web comprising a second fiber reinforced plastic, The first fiber reinforced plastic, the second fiber reinforced plastic and the spar cap each comprise a chemically decomposable polymer.

2. The wind turbine blade according to claim 1, wherein: The chemically decomposable polymer of each of the first fiber-reinforced plastic, the second fiber-reinforced plastic, and the third fiber-reinforced plastic is based on the same polymer system.

3. The wind turbine blade according to claim 1 , further comprising an adhesive comprising a chemically decomposable polymer, preferably the chemically decomposable polymer of the adhesive being based on the same polymer system as the chemically decomposable polymer of each of the first fiber reinforced plastic, the second fiber reinforced plastic, and the third fiber reinforced plastic.

4. A wind turbine blade according to any preceding claim, further comprising at least one wind turbine blade coating arranged on the blade shell, wherein The blade coating comprises a chemically decomposable polymer, preferably the chemically decomposable polymer of the wind turbine blade coating is based on the same polymer system as the chemically decomposable polymer of each of the first, second and third fiber reinforced plastics.

5. A wind turbine blade according to any preceding claim, wherein The core material is a foam core and comprises a chemically decomposable polymer, preferably the chemically decomposable polymer of the foam core material is based on the same polymer system as the chemically decomposable polymer of each of the first, second and third fiber reinforced plastics.

6. A wind turbine blade according to any preceding claim, wherein: The properties of the first component are different from the properties of the second component, wherein the first component and the second component are different components selected from the group consisting of the first fiber reinforced plastic, the second fiber reinforced plastic, and the third fiber reinforced plastic.

7. A wind turbine blade according to any preceding claim, wherein: The chemically decomposable polymer of the first component has properties different from properties of the chemically decomposable polymer of the second component, wherein the first component and the second component are different components selected from the group consisting of the first fiber reinforced plastic, the second fiber reinforced plastic, and the third fiber reinforced plastic.

8. A wind turbine blade according to any preceding claim, wherein The chemically decomposable polymer of each of the first fiber-reinforced plastic, the second fiber-reinforced plastic, the third fiber-reinforced plastic, and the foam core material may be chemically decomposable under the same process conditions.

9. The wind turbine blade of claim 6, wherein: The chemically decomposable polymer of the first component and the chemically decomposable polymer of the second component can be chemically decomposed under a first set of process conditions, wherein the chemical decomposition of the first component under the first set of process conditions is faster than the chemical decomposition of the second component under the first set of process conditions.

10. The wind turbine blade of claim 6, wherein: The chemically decomposable polymer of the first component is chemically decomposable under a first set of process conditions, and the chemically decomposable polymer of the second component is not chemically decomposable under the first set of process conditions.

11. A method for disassembling a wind turbine blade according to any one of claims 1 to 9, comprising the following steps: exposing the wind turbine blade to an acid to decompose the chemically decomposable polymer; preferably, the acid comprises formic acid, and Fiber is recovered from at least one of the first fiber-reinforced plastic, the second fiber-reinforced plastic, and the third fiber-reinforced plastic.

12. The method according to claim 11, wherein The acid causes the chemically cleavable polymer to reconstitute into at least one monomer and / or oligomer and / or polymer portion, the method further comprising recovering the monomer and / or oligomer.

13. The method according to claim 11 or 12, further comprising recovering non-fibrous material from the wind turbine blade, wherein optionally the non-fibrous material comprises metal, wood, undisassembled polymer and / or partially disassembled polymer.

14. The method of any one of claims 11 to 13, further comprising breaking the wind turbine blade into pieces prior to exposing to the acid.

15. The method of any one of claims 11 to 14, further comprising removing the spar or spar cap prior to exposure to the acid.

16. The method according to any one of claims 11 to 15, wherein The chemically decomposable polymer of the first component has properties different from properties of the chemically decomposable polymer of the second component, wherein the first component and the second component are different components selected from the group consisting of the first fiber reinforced plastic, the second fiber reinforced plastic, and the third fiber reinforced plastic, and The chemically decomposable polymer of the first component and the chemically decomposable polymer of the second component are chemically decomposable under a first set of process conditions, wherein the chemical decomposition of the first component under the first set of process conditions is faster than the chemical decomposition of the second component under the first set of process conditions, and Exposing the wind turbine blade to the acid to decompose the chemically decomposable polymer comprises the steps of first at least partially chemically decomposing the first component and the second component under the first set of process conditions, thereafter separating the second component from the first component, and thereafter decomposing the second component under a second set of process conditions.

17. The method according to any one of claims 11 to 15, wherein The chemically decomposable polymer of the first component has properties different from properties of the chemically decomposable polymer of the second component, wherein the first component and the second component are different components selected from the group consisting of the first fiber reinforced plastic, the second fiber reinforced plastic, and the third fiber reinforced plastic, and The chemically decomposable polymer of the first component is chemically decomposable under a first set of process conditions, and the chemically decomposable polymer of the second component does not chemically decompose under the first set of process conditions, and Exposing the wind turbine blade to the acid to decompose the chemically decomposable polymer comprises the steps of first at least partially chemically decomposing the first component under the first set of process conditions, thereafter separating the second component from the first component, and thereafter decomposing the second component under a second set of process conditions.

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