Concrete tower of enhanced conicity and wind turbine associated therewith

Abstract

A concrete tower for a wind turbine, comprising: a plurality of tower sections stackable one another to form a stack; a first portion of the stack comprises a first conicity or average conicity and a second portion of the stack comprises a second conicity or average conicity, the first portion having a first height ranging from a first end of the stack to a reference position of the stack between first and second ends, and the second portion having a second height ranging from the reference position of the stack to a second end of the stack; and the first conicity or average conicity is greater than or equal to 1.50 times the second conicity or average conicity. Also, a wind turbine, a wind farm, a method of manufacturing a concrete tower and a method of manufacturing a wind turbine.

Description

[0001] CONCRETE TOWER OF ENHANCED CONICITY AND WIND TURBINE

[0002] ASSOCIATED THEREWITH

[0003] TECHNICAL FIELD

[0004] The present disclosure relates to wind turbines. More particularly, the present disclosure relates to, but is not limited to, concrete towers for wind turbines and wind turbines with such towers.

[0005] BACKGROUND

[0006] Part or an entirety of the devices of a wind turbine that are used for producing electrical energy out of wind gusts, e.g., a nacelle, a rotor and blades of the wind turbine, are placed at a great height (e.g., 70 m or higher, 100 m or higher) with respect to a base or foundation of the wind turbine, thereby imposing certain structural requirements to a tower of the wind turbine.

[0007] In some cases, the tower is built by means of a number of tower sections that are stacked up, thereby erecting the tower. The tower sections are more easily transportable than a complete tower, and such construction eases disassembling of the wind turbine at the end of its useful life.

[0008] The tower and, more specifically, the tower sections thereof influence the total cost of the wind turbine, not only regarding the manufacturing, transportation and assembling, but also regarding its productivity, i.e. , its efficacy to produce electrical energy when wind moves the blades.

[0009] A balance should be struck between structural features of the tower and mechanical properties thereof to improve performance and cost of the wind turbine without compromising structural stability of the wind turbine, especially as they tend to be arranged in environments with harsh meteorological conditions.

[0010] DESCRIPTION

[0011] Aspects of the present disclosure are intended to provide wind turbines and towers thereof with more cost-effective manufacturing and / or assembling. Additionally or alternatively, aspects of the present disclosure are intended to provide wind turbines with greater productivity in terms of annual energy production (AEP).

[0012] A first aspect of the disclosure relates to a concrete tower for a wind turbine. The concrete tower includes a plurality of tower sections. The plurality of tower sections is stacked or stackable one another to form a stack such that a diameter of the tower sections varies, for example progressively, decreasing the diameter, from a first diameter to a second diameter. A tower section at a first end of the stack has the first diameter and a tower section at a second end of the stack has the second diameter. The first diameter is greater than the second diameter.

[0013] The first end corresponds to a bottom end of the tower and the second end corresponds to a top end of the tower. When the tower is erected, the first end is connected to a foundation and it is closest to a surface such as the ground, whereas the second end is generally connected to a nacelle or a steel tower in case the tower is a hybrid tower.

[0014] The concrete tower is for the part of concrete tower of a wind turbine, or a full concrete tower, or a hybrid tower (with concrete and steel sections). The concrete tower has a truncated cone shape.

[0015] The first and second diameters taken are either outer diameters or inner diameters, preferably outer diameters. In any case, a first inner diameter of the tower section at the first end is greater than a second inner diameter of the tower section at the second end, and a first outer diameter of the tower section at the first end is greater than a second outer diameter of the tower section at the second end.

[0016] A first portion or region of the stack has a first conicity or average conicity. A second portion or region of the stack has a second conicity or average conicity. The first portion or region has a first height ranging from the first end to a reference position of the stack that is between the first and second ends. The second portion or region has a second height ranging from the reference position of the stack to the second end.

[0017] In the context of the present disclosure, heights, including, e.g., the first and second heights, may be defined by an axis, such as a vertical axis (tower axis), extending from the first end to the second end or vice versa. Hereinafter, the first and second portions or regions will be referred to as first portion and second portion, respectively, although they could be referred to as first region and second region, respectively, as well. Preferably, the first and second portions each has a truncated cone shape. Also, the reference position may also be referred to as reference level without departing from the scope of the present disclosure.

[0018] The first conicity or average conicity is greater than the second conicity or average conicity.

[0019] Conicity, a, in degrees, of a tower section or a portion (e.g., first portion, second portion) can be calculated as follows:

[0020] _ Di ~ ^2

[0021] C~ h a = arctan where c is the conicity in dimensionless units or radians, Di is the greatest diameter of the tower section or portion, D2 is the smallest diameter of the tower section or portion, and h is the height (i.e., length) of the tower section or portion. Di and D2 are, preferably, the greatest and smallest outer diameters of the respective tower section or portion.

[0022] In the context of the present disclosure, conicity may be calculated for tower sections or portions regardless of whether respective lateral surface(s) or generatrix(es) thereof are straight or curved, said lateral surface(s) or generatrix(es) corresponding to an outer surface of the tower.

[0023] In some examples, Di is measured or measurable at an end of the tower section closest to the first end of the stack or at an end of the portion that is closest to the first end of the stack; D2 is measured or measurable at an opposite end to that for measuring Di , i.e., the end of the tower section or portion farthest away from the first end of the stack; and h is a height of the tower section or portion.

[0024] An average conicity may be calculated with a formula such as the aforementioned one. Particularly, the average conicity is an average of conicities calculated as, e.g., the mean (e.g., arithmetic mean, geometric mean) or the median of the conicities of a tower section or portion. A plurality of conicities is calculated per tower section or portion, and the average conicity thereof is calculated per tower section or portion.

[0025] Other suitable equations for calculating conicity, including but not limited to calculation of conicity in other units, are possible and also fall within the scope of the present disclosure. The term “conicity” is hereinafter used to refer to “conicity or average conicity”.

[0026] A tower according to the present disclosure may make a more cost-effective use of materials for manufacturing of the tower and / or more cost-effective assembling of the tower for example but without limitation, when volume and / or mass are / is reduced. By way of example, less volume of concrete can be used to build the stack, i.e., the tower, than other towers without such conicities.

[0027] The conicities of the tower influence the distance between blades of the wind turbine and the tower. Accordingly, the tower enables arranging blades that may be longer than blades arranged in some other towers because the blades can be kept at a distance from the tower and, as such, they do not contact the surface of the tower during operation. Therefore, if a tower according to the present disclosure is compared to other towers known in the art, for a same tower height, the presently disclosed tower may allow arranging longer blades than the other towers. By way of example, blades of a wind turbine that includes the tower according to the present disclosure may be less rigid than blades of wind turbines with other towers, and / or less steps for making the blades rigid are necessary in the manufacturing of the blades, thereby reducing manufacturing costs. Moreover, the distance between blades of the wind turbine and the tower influences energy production. As distance between the blades and the tower may be ensured, controlling operation of the wind turbine by adding safety mechanisms for avoiding that the blades clip with the surface of the tower may be reduced or avoided altogether. Each safety mechanism reduces the efficiency of the wind turbine, thereby reducing the AEP. Consequently, for a same wind power density, the wind turbine associated with the tower of the present disclosure yields, in some examples, a greater AEP than wind turbines having towers without such conicities; for example, but without limitation, a gain in AEP of 0.1 % or 0.2% may be achieved, in some cases even a gain of 1.0% or more may be achieved.

[0028] In some examples, the first conicity is greater than or equal to 1 .50 times the second conicity.

[0029] In some examples, the first conicity is smaller than or equal to 2.50 times the second conicity. That is to say, in some examples, the conicity of the portion closest to a foundation, when the tower is assembled, is between 1.50 to 2.50 times the conicity of the portion farthest away from the foundation.

[0030] Such conicity relationship reduces the likelihood of the blades of the wind turbine clipping the tower, especially when a rotor of the wind turbine is in operation and / or in presence of strong wind gusts or vortices.

[0031] In some examples, at least each tower section completely within the first portion has a conicity greater than a conicity of each tower section completely within the second portion.

[0032] In some examples, a conicity of one, some or all tower sections completely within the first portion is between 1.5 and 3.0 times a conicity of one, some or all tower sections completely within the second portion. Preferably, a conicity of one, some or all tower sections completely within the first portion is between 1.5 and 2.0 times a conicity of one, some or all tower sections completely within the second portion.

[0033] In some examples, the first conicity is between 1.00° and 2.50°. Preferably, the first conicity is between 1.05° and 2.00°. In some examples, the first conicity is between 1.10° and 2.00°.

[0034] In some examples, the second conicity is between 0.60° and 1.30°. Preferably, the second conicity is between 0.70° and 1.20°. In some examples, the second conicity is smaller than or equal to 1 .05°.

[0035] In some examples, a ratio defined by an outer diameter of the tower at a predetermined height thereof divided by an outer diameter of the tower at the first end of the stack is between 0.70 and 0.90, and preferably the ratio is between 0.75 and 0.85. The predetermined height for the ratio corresponds to the reference position and / or a height of the tower at where a tip of blades of the tower or wind turbine is when the respective blade is arranged according to six o’clock.

[0036] Such ratio characterizes the reduction of outer diameter at the predetermined height with respect to the outer diameter at the first end, i.e., at the part of the tower section that is attached to the ground or a foundation. Some known towers feature a ratio greater than 0.90, for example equal to or greater than 0.95. Accordingly, a tower according to these examples achieves a greater reduction in outer diameter of the tower at the reference position than known towers, which consequently enables attachment of longer blades and / or avoiding that the blades clip with the surface of the tower.

[0037] In some examples, the plurality of tower sections has two or more tower sections with different height.

[0038] In some examples, the plurality of tower sections has two or more tower sections with same height.

[0039] In some examples, the reference position is at a distance smaller than or equal to 1 / 3 (i.e., one third) of a height of the stack from the first end. That is to say, the reference position is at a distance greater than or equal to 2 / 3 (i.e., two thirds) of a height of the stack from the second end.

[0040] In some examples, the reference position is at a distance greater than or equal to 1 / 8 (i.e., one eighth) of a height of the stack from the first end. That is to say, the reference position is at a distance smaller than or equal to 7 / 8 (i.e., seven eighths) of a height of the stack from the second end.

[0041] In some examples, the reference position is, with respect to a height of the tower or stack, at a distance greater than or equal to 0.85 times a predetermined length of a blade of the wind turbine (i.e., a blade configured to be installed in the wind turbine) from the second end, and / or greater than or equal to the predetermined length of a blade of the wind turbine minus 10 m from the second end. Preferably, the distance is greater than or equal to 0.9 and / or 0.95 and / or 1 .0 times the predetermined length of the blade.

[0042] In some examples, the reference position is, with respect to a height of the tower or stack, at a distance smaller than or equal to 1.15 times a predetermined length of a blade of the wind turbine (i.e., a blade configured to be installed in the wind turbine) from the second end, and / or smaller than or equal to the predetermined length of a blade of the wind turbine plus 10 m from the second end. Preferably, the distance is smaller than or equal to 1.1 and / or 1.05 and / or 1.0 times the predetermined length of the blade.

[0043] In some examples, the predetermined length of the blade (from a root thereof to a tip thereof) is greater than or equal to 75 m. Preferably, the predetermined length is greater than or equal to 80 m. In some examples, the predetermined length of the blade (from a root thereof to a tip thereof) is smaller than or equal to 90 m. Preferably, the predetermined length is smaller than or equal to 85 m.

[0044] In some examples, the predetermined length of the blade is between 80 and 83 m.

[0045] In some examples, the predetermined length of the blade is greater than or equal to 0.6 times the height of the stack, i.e., of the tower.

[0046] In some examples, the predetermined length of the blade is smaller than 0.9 times the height of the stack.

[0047] In some examples, the reference position is a position of minimum blade tip to tower distance. The minimum blade tip to tower distance may be a TCA distance, i.e., tower closest approach distance.

[0048] In some examples, an outer diameter of a tower section at the reference position is between 4.0 and 8.0 m, preferably between 5.0 m and 7.0 m.

[0049] In some examples, an outer diameter of the tower section at the first end of the stack is between 6.0 m and 9.0 m, preferably between 7.0 m and 8.5 m, and more preferably between 7.25 m and 8.0 m, and an outer diameter of the tower section at the second end of the stack is between 2.5 m and 5.0 m, preferably between 3.0 m and 4.5 m, and more preferably between 3.5 m and 4.0 m.

[0050] In some examples, the concrete tower includes any one of: a rotor with a plurality of blades, a nacelle, a drive train, a gearbox, a generator, a steel tower, or a combination thereof. In some examples, each blade of the plurality of blades has the predetermined length.

[0051] In some examples, the rotor is arranged on the stack, i.e., the tower, with a conning smaller than or equal to 10°. Preferably, the conning is smaller than or equal to 5°.

[0052] A second aspect of the disclosure relates to a wind turbine. The wind turbine includes a concrete tower as described in the first aspect.

[0053] The first end of the concrete tower is adapted to include or be connected to a foundation. The second end of the concrete tower is adapted to include or be connected to a nacelle or a steel tower.

[0054] In some examples, the wind turbine includes a rotor with a plurality of blades.

[0055] In some examples, the wind turbine includes a nacelle.

[0056] In some examples, the wind turbine includes a drive train.

[0057] In some examples, the wind turbine includes a gearbox.

[0058] In some examples, the wind turbine includes a generator.

[0059] In some examples, the wind turbine includes a steel tower. In some examples, a ratio of A1 divided by A2 is defined, and the ratio is smaller than or equal to 0.625. Preferably, the ratio is smaller than or equal to 0.525. More preferably, the ratio is smaller than or equal to 0.40.

[0060] In some examples, the ratio is greater than or equal to 0.20.

[0061] A1 is, when the rotor is in operation, a first minimum distance between a tip of one or more blades of the plurality of blades and the tower. A2 is, when the rotor is not in operation, a second minimum distance between the tip of the one or more blades and the tower.

[0062] The rotor being in operation preferably means that the blades are moving at a speed greater than a predetermined speed such as, for example but without limitation, 0.62 rad / s, or rotating such that the blades at least perform a predetermined number of revolutions per minute as, for example but without limitation, 6 rpm. The rotor not being in operation preferably means that the blades are moving at a speed lower than or equal to a predetermined speed such as, for example but without limitation, 0.62 rad / s, or rotating such that the blades perform fewer revolutions than a predetermined number of revolutions per minute as, for example but without limitation, 6 rpm. In some cases, the rotor is not in operation when the blades are not moving or rotating.

[0063] In some examples, A1 is between 1 / 15 (i.e. , one fifteenth) and 1 / 8 (i.e. , one eighth) times a length of the one or more blades (from a root thereof to a tip thereof), and A2 is between 1 / 6 (i.e., one sixth) and 1 / 3 (i.e., one third) times the length of the one or more blades.

[0064] In some examples, the minimum blade tip to tower distance varies between A1 and A2 when the rotor is in operation and when the rotor is not in operation, respectively.

[0065] In some examples, the reference position is a position of minimum blade tip (of the one or more blades) to tower distance.

[0066] A third aspect relates to a wind farm. The wind farm may include a plurality of wind turbines as described in the second aspect. The wind farm may additionally or alternatively include a plurality of concrete towers as described in the first aspect.

[0067] A fourth aspect relates to a method of manufacturing a concrete tower. The method includes the step of arranging a plurality of tower sections. The method also includes the step of stacking the plurality of tower sections up to form a stack (and, thus, a concrete tower) as described in the first aspect.

[0068] Accordingly, in examples, the plurality of tower sections is stacked up to form a stack, thereby providing the concrete tower, such that at least: a tower section at a first end of the stack has the first diameter and a tower section at a second end of the stack has the second diameter, with the first diameter being greater than the second diameter; a diameter of the stack decreases, progressively or intermittently, from the first diameter to the second diameter between the first and second ends of the stack; a first portion of the stack has a first conicity and a second portion of the stack has a second conicity, with the first portion having a first height ranging from the first end to a reference position of the stack between the first and second ends, and the second portion having a second height ranging from the reference position of the stack to the second end; and the first conicity is greater than the second conicity.

[0069] Examples as those described with reference to the first aspect may also be manufactured with the method of the fourth aspect in some examples.

[0070] A fifth aspect relates to a method of manufacturing a wind turbine. The method includes a step of arranging a plurality of tower sections. The method also includes a step of stacking the plurality of tower sections up to form a stack (and, thus, a concrete tower) as described in the first aspect. The method also includes a step of arranging a nacelle with a rotor, or a steel tower with the nacelle, at the second end of the stack. The rotor includes a plurality of blades.

[0071] In some examples, the reference position delimiting the first portion and the second portion of the stack is at a distance, from the second end, between 0.85 and 1.15 times a length of one or more blades of the plurality of blades. In some examples, the reference position is close to the blade tip in height, and that closeness is with a variation of ±15% and / or ±10 m in height.

[0072] In some examples, the reference position delimiting the first portion and the second portion of the stack is at a distance, from the first end, between 1 / 8 (i.e. , one eighth) and 1 / 3 (i.e., one third) of a height of the stack.

[0073] Examples as those described with reference to the first aspect and / or the second aspect may also be manufactured with the method of the fifth aspect in some examples.

[0074] BRIEF DESCRIPTION OF THE DRAWINGS

[0075] To complete the description and in order to provide for a better understanding of the disclosure, a set of drawings is provided. Said drawings form an integral part of the description and illustrate examples and embodiments of the disclosure, which should not be interpreted as restricting the scope of the disclosure, but just as examples of how the disclosure can be carried out. The drawings comprise the following figures: Figure 1 shows a wind turbine in accordance with some examples.

[0076] Figure 2 shows a wind turbine in accordance with some examples.

[0077] Figure 3 shows a tower section of a tower in accordance with some examples.

[0078] Figure 4 shows a wind turbine in accordance with some examples.

[0079] Figure 5 shows a tower in accordance with some examples.

[0080] Figure 6 shows a tower in accordance with some examples.

[0081] DETAILED DESCRIPTION

[0082] Figure 1 shows a wind turbine 10 in accordance with some examples, particularly with the wind turbine and a rotor thereof not in operation. Figure 2 also shows a wind turbine 10 in accordance with some examples, for example the same wind turbine 10 of Figure 1 with blades of the wind turbine moving, thus with the wind turbine and a rotor thereof in operation.

[0083] The wind turbine 10 includes a tower 20 with stacked up tower sections 21 between a first end 22 and a second end 23 according to an axis h (e.g., a vertical axis, a tower axis), which may correspond to a height axis of the tower 20 when assembled on or in a surface 1 , e.g., a ground. Each tower section 21 has or is made of concrete.

[0084] The wind turbine 10 may also include a nacelle 50 arranged at the second end 23 of the tower 20, a rotor 40 and a plurality of blades 30. Each blade ends on a tip 30’ thereof and has a length 31 along a length axis of the respective blade, which may be measured when the blade is not moving or when the rotor 40 is not in operation.

[0085] Each tower section 21 of the tower 20 has a frustoconical shape with a base surface larger than a top surface, as it will be explained in more detail in Figure 3.

[0086] A minimum blade tip to tower distance 35, A1 , A2 may be measured from the tip 30’ when blades 30 are moving and / or when blades 30 are motionless, i.e., when the rotor 40 is in operation and / or when the rotor 40 is not in operation. The distance 35 is the minimum distance that may be measured, in a straight line perpendicular to the axis h (and, when the tower is assembled on a ground, parallel to the ground in a horizontal plane), e.g., the tower axis, to a closest point on the surface of the tower 20. When blades 30 are moving, such as in Figure 2, the minimum blade tip to tower distance A2 may be smaller than the distance A1 when blades 30 are motionless owing to the flection of the blades 30. In the context of the present disclosure, the minimum blade tip to tower distance 35 is preferably measured when the blade 30 is at a six o’clock position when observing the tower 20 from a front thereof, namely, the blade 30 is facing the tower and downwards to the surface 1 (e.g., the ground), such as in Figures 1 and 2, so that the distance is the minimum that can be measured owing to the geometry of the tower 20 and the greater proximity between the tip 30’ of the blade 30 and an external surface of the tower 20, particularly the external surface of the closest tower section 21 .

[0087] As illustrated in Figure 2, a first portion 24a and a second portion 24b of the tower

[0088] 20 may be defined with respect to a given reference position 24’, which may correspond to a cross-section of the tower 20 that is taken perpendicularly to the axis h (e.g., the tower axis); the first portion 24a is the portion closest to the surface 1 when the tower 20 is assembled thereon or therein, whereas the second portion 24b is the portion farthest away from the surface 1 when the tower 20 is assembled thereon or therein. The reference position 24’ may be, for example, at a distance between 0.125 (i.e. , 1 / 8) and 0.333 (i.e. , 1 / 3) of a height (illustrated with arrowed line L) of the tower 20 measured from the first end 22, and / or at a distance between 0.85 and 1.15 times the length 31 of the blades 30 measured from the second end 23. By way of example, but without limitation, the distance from the second end 23 is between 68 m and 92 m.

[0089] A conicity may be defined and computed for each of the first portion 24a and the second portion 24b. The conicity of the first portion 24a, which depends on the tower section(s) 21 (if any) within the first portion 24a and also on part of a tower section 21 at the reference position 24’ (particularly the part within the first portion 24a), is greater than the conicity of the second portion 24b, which depends on the tower section(s) 21 within the second portion 24b and also on part of a tower section 21 at the reference position 24’ (particularly the part within the second portion 24b).

[0090] Although not illustrated, in some examples, the reference position 24’ falls at an interface between two tower sections 21 and, thus, the conicity of the first portion 24a is defined and computed considering the tower sections 21 within the first portion 24a and the conicity of the second portion 24b is defined and computed considering the tower sections

[0091] 21 within the second portion 24b.

[0092] Figure 3 shows a tower section 21 of a tower in accordance with some examples.

[0093] The tower section 21 has a base surface with an outer diameter 28 and a top surface with an outer diameter 29. The tower section 21 is frustoconical with respect to a height or length 27 dimension, which upon stacking two or more tower sections 21 is a dimension parallel to a height axis h as illustrated in Figure 1.

[0094] A conicity can be calculated per tower section 21 based on length 27 and outer diameters 28, 29.

[0095] When a tower section 21 is not completely within a tower portion such as the first portion 24a or the second portion 24b as illustrated in Figure 2, a third outer diameter may be defined along the height or length 27. Particularly, a cross-section taken at the reference position 24’ defines a circumference within the height or length 27 dimension. The outer diameter resulting from the cross-section may be considered for computing the conicity of both the first and second portions 24a, 24b as it acts as top surface for the first portion 24a and base surface for the second portion 24b. In these cases, it must be considered that the reference position 24’ is defined for the entire tower, thus when considering an intermediate tower section 21 of the tower with the reference position 24’ being at such intermediate tower section 21 , the height difference between the reference position 24’ (with respect to the first end) and the height or length 27 of all tower sections 21 to be beneath the intermediate tower section 21 must be computed. The diameters considered for the conicities in such situation are that at the first end and at the reference position 24’ for the first portion, and the diameters at the reference position 24’ and the second end for the second portion.

[0096] Figure 4 shows a wind turbine 10 in accordance with some examples.

[0097] The wind turbine 10 includes a tower 20 with two stacked up tower sections 21 between a first end 22 and a second end 23. Each tower section 21 has or is made of concrete.

[0098] Like in Figures 1 and 2, the wind turbine 10 may also include a nacelle 50 arranged at the second end 23 of the tower 20, a rotor 40 and a plurality of blades 30. Each blade ends on its tip 30’.

[0099] The tower 20 has a reference position 24’ delimiting first and second portions 24a, 24b. The first portion 24a has a conicity that is preferably equal to or greater than 1 .50 times the conicity of the second portion 24b.

[0100] The tower 20 is configured to make the tip 30’ of the blades 30, when positioned according to six o’clock on the rotor 40, to be within a predetermined height interval 60 that extends parallelly to the tower axis. The predetermined height interval 60 is defined centered at the reference position 24’, and the interval extends along both ends a respective predetermined distance 60a, 60b. The predetermined distance 60a, 60b may be, for example, 10 m or less in height of the tower. By having the tips 30’ be at a height falling within the predetermined height interval 60 when the blade is arranged according to six o’clock, a distance between the tip 30’ and the surface of the tower 20 may be ensured to let the blades 30 rotate without clipping the tower 20.

[0101] The distance of ends of the predetermined height interval 60 from any of the first and second ends 22, 23 along the tower axis can be computed based on the reference position 24’. By way of example, an end of the predetermined height interval 60 closest to the first end 22 is at a height of the reference position 24’ minus the predetermined distance 60a.

[0102] Figure 5 shows a tower 20 in accordance with some examples. The tower 20 includes a plurality of tower sections which has respective ends at a first end 22 and a second end 23. Each tower section starts and / or ends at indentations 39. Each tower section has outer diameters 25 and inner diameters 26. Conicities may be computed with either diameters 25, 26, yet all conicities are to be computed with the same type of diameters, thus outer or inner diameters, preferably outer diameters 25.

[0103] In the example of Figure 5, at least part of the tower 20 does not have a regular lateral surface or generatrix; particularly, the lateral surface or generatrix has a slope with changing sign corresponding to concave and convex slopes at different vertical positions of the tower 20. More particularly, a first portion 24a of the tower 20 has a curved generatrix, and a bottom-most part of a second portion 24b of the tower 20 also has a curved generatrix, whereas a top-most part of the second portion 24b has a substantially straight generatrix. In some other examples, a tower 20 has differently shaped generatrixes.

[0104] The following table shows the ranges of heights and outer diameters of the tower 20 at different heights.

[0105] Namely, a first portion is defined between the base and the reference position 24’, and it has a height between 15.0 and 30.0 m; and a second portion is defined between the reference position 24’ and the top, and it has a height between 60.0 and 100.0 m.

[0106] Figure 6 shows a tower 20 in accordance with some examples.

[0107] Like in Figure 5, the tower 20 includes a plurality of tower sections which have respective ends at a first end 22 and a second end 23. Each tower section starts and / or ends at indentations 39. In comparison with the tower 20 of Figure 5, which has five tower sections, the tower 20 of Figure 6 has six tower sections. In other examples, the tower 20 has more tower sections or less tower sections, e.g., two tower sections or more than two tower sections.

[0108] The following table shows the ranges of heights and outer diameters of the tower 20 at different heights. Namely, a first portion is defined between the base and the reference position 24’, and it has a height between 30.0 and 50.0 m; and a second portion is defined between the reference position 24’ and the top, and it has a height between 55.0 and 105.0 m.

[0109] It will be noted that combinations of tower sections, heights, diameters (outer and / or inner) and generatrixes (or lateral surfaces) other than those shown, for the sake of clarity only, with reference to Figures 5 and 6 are also possible within the scope of the present disclosure.

[0110] In some examples, a tower 20 such as, but without limitation, any of those shown in Figures 5 and 6, when erected, is configured to have a tip of at least one blade to be at a height from the first end that the reference position 24’ is at plus-minus 10 m, therefore within a predetermined height interval 60 as described with reference to the tower 20 of Figure 4.

[0111] In the context of the present disclosure, all disclosed ranges also include the endpoints thereof.

[0112] In this text, the term “includes”, “comprises” and derivations thereof (such as “including”, “comprising”, etc.) should not be understood in an excluding sense, that is, these terms should not be interpreted as excluding the possibility that what is described and defined may include further elements, steps, etc.

[0113] On the other hand, the disclosure is obviously not limited to the specific example(s) and embodiment(s) described herein, but also encompasses any variations that may be considered by any person skilled in the art (for example, as regards the choice of materials, dimensions, components, configuration, etc.), within the general scope of the invention as defined in the claims.

Claims

CLAIMS1 . A concrete tower (20) for a wind turbine (10), the concrete tower comprising: a plurality of tower sections (21) stackable one another to form a stack such that a diameter of the tower sections varies from a first diameter to a second diameter; wherein a tower section at a first end (22) of the stack has the first diameter and a tower section at a second end (23) of the stack has the second diameter, the first diameter being greater than the second diameter; wherein a first portion (24a) of the stack comprises a first conicity or average conicity and a second portion (24b) of the stack comprises a second conicity or average conicity, wherein the first portion has a first height ranging from the first end to a reference position (24’) of the stack between the first and second ends, and wherein the second portion has a second height ranging from the reference position (24’) of the stack to the second end, wherein the first and second heights are defined by an axis (h) extending from the first end to the second end; and wherein the first conicity or average conicity is greater than or equal to 1 .50 times the second conicity or average conicity.

2. The concrete tower (20) of claim 1 , wherein the first conicity or average conicity is smaller than or equal to 2.50 times the second conicity or average conicity.

3. The concrete tower (20) of any one of the preceding claims, wherein the first conicity or average conicity is between 1.00° and 2.50°.

4. The concrete tower (20) of any one of the preceding claims, wherein the second conicity or average conicity is between 0.60° and 1.30°.

5. The concrete tower (20) of any one of the preceding claims, wherein the tower section (21) at the first end (22) is adapted for arrangement of the stack to a ground or foundation, and wherein the tower section (21) at the second end (23) is adapted for attaching a nacelle (50) or a steel tower thereto.

6. The concrete tower (20) of any one of the preceding claims, wherein the first portion (24a) and / or the second portion (24b) has a generatrix or lateral surface that is curved.

7. The concrete tower (20) of any one of the preceding claims, wherein the reference position (24’) is at a distance: from the first end (22), between 1 / 8 and 1 / 3 of a height (L) of the stack; and / or from the second end (23), between 0.85 and 1.15 times a predetermined length (31) of a blade (30) configured to be installed in the wind turbine (10).

8. The concrete tower (20) of any one of the preceding claims, wherein an outer diameter of a tower section (21) corresponding to a cross-section taken at the reference position (24’) is between 5.0 m and 7.0 m.

9. A wind turbine (10) comprising: a concrete tower (20) according to any one of the preceding claims; and a rotor (40) with a plurality of blades (30).

10. The wind turbine (10) of claim 9, wherein the reference position (24’) of the concrete tower (20) is located at a tower height, from the first end (22) and measured along the axis (h), equal to the height of the tip (30’) of the blade (30) plus-minus 10 m.11 . The wind turbine (10) of claim 10, wherein the reference position (24’) is located at the tower height between the height of the tip (30’) of the blade (30) and the height of the tip (30’) of the blade (10) minus 10 m.

12. The wind turbine (10) of any one of claims 9-11 , wherein the first end (22) of the concrete tower is adapted for being adjacent to a ground or foundation.

13. A wind farm comprising: a plurality of wind turbines (10) according to any one of claims 9-12 and / or a plurality of concrete towers (20) according to any one of claims 1-8.

14. A method of manufacturing a concrete tower (20), the method comprising: arranging a plurality of tower sections (21); and stacking the plurality of tower sections up so as to form a concrete tower according to any one of claims 1-8.

15. A method of manufacturing a wind turbine (10), the method comprising: arranging a plurality of tower sections (21); stacking the plurality of tower sections up for providing a concrete tower (20) such that:a diameter of the concrete tower varies from a first diameter to a second diameter; a tower section at a first end (22) of the concrete tower has the first diameter and a tower section at a second end (23) of the concrete tower has the second diameter, the first diameter being greater than the second diameter; a first portion (24a) of the concrete tower comprises a first conicity or average conicity and a second portion (24b) of the concrete tower comprises a second conicity or average conicity, wherein the first portion has a first height ranging from the first end to a reference position (24’) of the concrete tower between the first and second ends, and wherein the second portion has a second height ranging from the reference position (24’) of the concrete tower to the second end, wherein the first and second heights are defined by an axis (h) extending from the first end to the second end; and the first conicity or average conicity is greater than or equal to 1 .50 times the second conicity or average conicity; and arranging a nacelle (50) with a rotor (40), or a steel tower with the nacelle, at the second end of the concrete tower, the rotor comprising a plurality of blades (30).

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