Patent Application
20180148140
The present invention relates to a floating construction intended to be installed accordingly in a location on a body of water, a lake or the like, and a method for installing the same.
The construction of the present invention can be a floating substructure for a wind turbine, made in part from concrete, which in an installed condition comprises either a semi-emerged shaft and a submerged flotation base, or an emerged shaft and a semi-submerged flotation base. In this context the term “substructure” refers to the part of a wind tower intended to support thereon the generation means of the wind tower, therefore including the tower itself or shaft.
For the sake of clarity in the description, the present document will refer in general to the use of a construction according to the present invention in the sea, without this limiting the scope of the invention with regard to the body of water for the location in accordance with the present invention. Similarly, for the sake of clarity in the description, the present document will specifically illustrate a floating substructure construction for a wind turbine, without this limiting the scope of the invention.
Although as indicated above this invention is particularly applicable for floating substructures made in part from concrete, this should not be understood as limiting the scope of the description or the claims to the application of the subject matter in this type of construction, nor in substructures made in part from concrete, as the present invention is equally advantageous for use in substructures which when installed have a bottom segment made mainly from concrete up to a certain height above the water level and mainly from another material (such as steel) above said height, and is also applicable although not preferable in substructures made of a material other than concrete (such as steel) in their entire vertical dimension.
Thus, the main field of application of the present invention is the large-scale structure construction industry, particularly with concrete, in combination with the industry of renewable or green power, specifically wind power.
It is well known that wind power has gained great relevance in recent years in Spain, Europe and the rest of the world. All forecasts point to a sustained growth in wind power generation worldwide. Energy policies of the most advanced and richest countries include among their goals an increased presence of wind power.
Within this context, offshore wind farms are beginning to appear, confirming the expectation of great growth in the use of this technology in coming years. Offshore wind farms clearly entail greater costs, depending of course on the depth of the water at their location, but the wind quality is better, wind speeds are higher and turbulence is lower, resulting in more production hours which, in addition to the higher density of air at sea level generates higher income than land-based wind farms, compensating for the higher initial investment costs. In fact, it is now common, particularly in Germany, Great Britain and Scandinavian countries to promote and build offshore wind farms, with a great number of such farms being studied, in line with the expected growth of this type of wind farms, closely linked to strategic goals set by governments for reaching specific renewable energy production quotas. The trend towards using turbines with greater power and size in order to reduce the unit costs of the installed power has been constant in the development of wind turbines, particularly so for offshore wind power. Nearly all large wind turbine manufacturers are studying or in the later stages of developing high power models, with 3 or more megawatts, adapted to marine conditions, which are particularly demanding.
This power escalation and the particularly demanding marine conditions in turn imply a considerable increase in the demands on the substructure that must support the turbines, which requires developing novel concepts for said substructure with increased capacity, optimum strength and a competitive cost, particularly if the substructure will be used in locations with great depth, which may be advisable in some circumstances. Floating solutions have been proposed for these sites, all of which have been built so far have used a metal substructure.
Among the main drawbacks and limitations of known floating solutions are the following:
With regard to the manufacturing material, structural concrete turns out to be an optimum material for constructions on water, particularly marine offshore constructions. In fact, although the use of metal structures is predominant in mobile floating elements, as an extension of naval practice and always linked to continuous maintenance, concrete is instead an advantageous alternative and is therefore more common in all types of fixed maritime constructions (ports, docks, breakwaters, platforms, lighthouses, etc.). This is mainly due to the durability, robustness and structural strength, reduced sensitivity to marine corrosion and practically maintenance-free service of structural concrete. With a proper design, fatigue sensitivity is also very low. Its useful lifetime generally exceeds 50 years.
Moreover, concrete is advantageous due to its tolerance in case of impact or collisions, and can be designed for example to withstand forces generated by drifting ice or the impact from small ships, as well as due to the simplicity and economy of any necessary repairs.
Structural concrete is also a universal construction material, and the raw material and construction means are accessible worldwide and have moderate costs.
For this reason, concrete is increasingly used to build offshore substructures, although until now it has been generally used for substructures with foundations on the seabed, and therefore for small depths or complex structures.
One object of the present invention relates to a floating construction comprising:
Said floating construction can comprise in the installed conditions either a semi-emerged type building and a submerged type flotation base, or an emerged type building and a semi-submerged flotation base. In this regard, in the specific case that the floating construction is used to support a wind turbine, in the present invention it is considered that the part of the wind tower at a lower height than the maximum height of any component of the flotation base forms part of said flotation base.
Said floating construction can be a floating substructure for a wind turbine, specifically a floating substructure substantially made from concrete, and said building can comprise a shaft or tower with at least two segments, including a base segment and a head segment, supporting the wind turbine means. Said shaft can preferably be telescopic.
Said shaft is formed from at least two tubular segments placed on each other coaxially, possibly with partial axial overlap, until reaching the planned height, of which at least one can be tapered in an upward direction in the installed condition of the substructure. Between two successive segments there is therefore a corresponding horizontal union. Among the shaft segments, the shaft segment intended to be placed directly on said flotation base in the installed condition of the substructure is hereinafter referred to as the “base segment” and any segment other than the base segment is hereinafter referred to as a “superposition segment”. The superposition segment intended to be placed at the top of the shaft in the installed condition of the substructure is hereinafter referred to as the “head segment”.
Each one of these segments can be a single piece (hereinafter referred to as an “integral segment”). Alternatively, at least one of said segments can be formed by at least two arched segments, joined to complete the circumference of the corresponding segment. Between two successive arched segments there is therefore a corresponding vertical union.
In addition, the base segment of a substructure shaft and the flotation base of said substructure can be joined continuously or be made from a single piece, without departing from the scope of the invention.
Said floating construction can therefore be a floating substructure for a wind turbine, particularly a floating substructure mainly made from concrete, comprising in its installed condition either a semi-emerged shaft and a submerged flotation base, or an emerged shaft and a semi-submerged flotation base, where said floating substructure for a wind turbine comprises:
The floating construction in accordance with the present invention can also comprise a stay the upper end of which is joined to the building, preferably a shaft, and the lower end of which is joined to the flotation base. At least one of said stays is inclined such that the lower end of the stay is farther from the central vertical axis of the building than the upper end of the stay. At least one of said stays can be formed by the extension of a corresponding retaining cable, in which case the flotation base comprises a deflection element that allows creating an elbow in the alignment of the retaining cable and the upper end of the retaining cable is finally joined to the building.
The flotation base can be a structure that comprises a single body comprising at least a cavity, sealed, in the form of a box, that is preferably made from concrete, or can be a structure comprising at least two bodies comprising at least a cavity, sealed in the form of a box, of which at least one is preferably made from concrete, said bodies joined to each other directly or through a structure such as a lattice or bar structure. Each of said bodies can have one or several inner compartments, sealed or in communication with each other.
A floating construction in accordance with the present invention can be transported over water by towing or self-propulsion to the final location. For this purpose, the flotation base and at least part of the building can form a transportation unit that is floating and free standing. In the case of a floating construction that is a floating substructure for a wind turbine comprising a telescopic shaft according to the present invention, the flotation base, the telescopic shaft in its retracted condition (that is, with the base segment integrally joined to the flotation base and the superposition segments provisionally housed inside each other and inside the base segment), and at least part of the turbine means joined to the head segment of said telescopic segment, can form a transportation unit that is floating and free standing. The telescopic shaft in its retracted condition allows lowering the centre of gravity of the transportation unit and thereby improving its stability.
Preferably, during transportation the flotation base remains semi-submerged and the building, including if applicable the telescopic shaft in its retracted position, remains completely emerged. However, in the installed condition of the substructure, the flotation base is preferably completely submerged and the building is partially submerged.
In the installed condition of the construction, the central vertical axis of the building coincides with the central vertical axis of the flotation base.
The aforementioned downward impelling means can exert a downward force or act as ballast on said flotation base. Said downward impelling means can comprise at least one massive element suspended from the retaining cables and completely submerged, located below the flotation base and above the seabed. In this case, at least part of said retaining cables are not vertical but instead are inclined with respect to the vertical line, the upper end thereof being farther from the central axis of the flotation base than the bottom end. Preferably, the massive element is essentially located on the central vertical axis of the flotation base. Preferably, the massive element comprises a concrete box, body comprising at least a cavity, the interior of which in the installed condition is completely or partially filled with ballast material, which can be a liquid or solid material. Said massive suspended element further comprises means for adjusting the volume and/or weight of said ballast material, which allows regulating the submerged weight of said suspended mass and in this way regulating the depth or level at which the floating construction is placed, to adapt this particularly in view of the wind or wave conditions.
Said concrete box can be self buoyant and free standing in a partially ballasted or unballasted condition, such that it can be towed to the location and ballasted on site to submerge it until reaching the final position with respect to the flotation base.
Preferably, the weight or ballast of said suspended massive element is enough for the centre of gravity of the whole of the floating construction to descend to a level lower than the centre of buoyancy of said floating construction, thereby improving its stability.
The construction in accordance with the present invention can also comprise lateral means for maintaining the position that join the floating construction to the seabed, thereby preventing the construction from drifting, particularly when the downward impelling means do not include means of attachment to the seabed. Said means for maintaining the lateral position can comprise at least one mooring attached on one end to the seabed and on the other end to any element of the floating construction, such as to any of the elements comprised in the flotation base, a suspended massive element or even to the building. The attachment of said mooring to the seabed can be performed by various systems known in the art, such as anchors, single point mooring, driven or suction piles, or simply by gravity, such that the mooring is attached to a massive element that allows attachment to the seabed.
At least one of said massive elements, whether a massive element of the attachment means to the seabed or a suspended massive element, can provisionally abut against the flotation base. Thus at least one of said abutting massive elements can form part of the transportation unit and be transported together with the flotation base and the building, and subsequently released or separated from the flotation base until reaching its position in the installed condition of the construction.
The floating construction according to the present invention can comprise means for provisional collection of the retaining cables to transport them wound or in reels, forming part of the transportation unit and/or part of at least one massive element. Said elements allow efficient transportation of the retaining cables, such that during the installation of said cable it can be wound or unwound gradually, improving the efficiency and simplicity of the installation process, especially when the downward impelling means comprise massive elements which are ballasted for gradual descent until reaching the installed condition of the floating construction.
In addition, the flotation base of a floating construction according to the present invention can comprise at least one extensor arm that extends laterally outward from the perimeter of the body or group of bodies of the flotation base. In this case, at least one of the retaining cables can be attached at its upper end to a corresponding extensor arm, preferably to the free end of a corresponding extensor arm. In this case, at least one of the stays can be attached at its lower end to a corresponding extensor arm. Also in this case, at least one of said stays can be formed by the extension of a corresponding retaining cable, in which case the extensor arm comprises, preferably at its free end, a deflection element that allows creating an elbow in the alignment of the retaining cable and the upper end of the retaining cable is finally joined to the building. Also in this case the lateral means for maintaining the position can be attached on one end to the seabed, and on the other end to at least one of said extensor means.
The floating construction according to the present invention can include under the flotation base at least one chamber with pressurised gas (for example, pressurised air) that increases the volume of water displaced by the flotation base and therefore increases the upward buoyancy force exerted on it. The enclosure containing said pressurised gas chamber is open on the bottom such that it is connected to the body of water of the site. In addition, means for controlling and adjusting the volume and/or pressure of the air contained in said pressurised gas chamber can be provided, allowing to regulate the upward buoyancy force on the flotation base and in this way regulate the depth or level at which the floating construction is placed, to adapt this particularly in view of the wind or wave conditions. It is also possible to adjust the depth of the floating construction by changing the amount of ballast in the flotation base and/or in at least one massive suspended element operatively connected through means 18 to the at least one chamber with pressurized gas under the flotation base to adjust the weight of the massive element by increasing or decreasing the amount of ballast material in it.
Moreover, in this case the floating construction in accordance with the present invention can include on the flotation base means for harnessing energy from waves, which include at least one Wells type turbine on an air passage through the bottom side of the flotation base, communicating the sealed internal enclosure of the flotation base and/or the building with said pressurised gas chamber. Furthermore, the floating construction in accordance with the present invention can comprise a system for regulating the size of at least one pressurised gas chamber by adjusting the volume and/or pressure of the air contained therein, which allows adjusting the resonant frequency in said pressurised gas chamber to the predominant period ranges in the incident waves, thereby increasing the oscillations of the water level in said pressurised gas chambers caused by the waves and the energy harnessing thereof.
Said Wells type turbines allow harnessing the energy from waves by the method known as oscillating water column; the waves produce rises and falls in the water sheet inside the enclosure containing the pressurised gas chamber, thereby propelling air through the passage between the gas chamber under the flotation base and the inside of the base of the flotation chamber or the shaft. The Wells type turbine can generate energy using the air flow through said passage in either direction.
Although the Wells turbine is the preferred type, other types of turbines known in the art can be used to harness the energy from a moving fluid without thereby departing from the scope of the invention.
Another object of the present invention relates to a method for installing a floating construction as described above.
The installation method according to the present invention comprises the following steps, in any technically possible order:
A) manufacturing the flotation base on-shore or in-shore,
B) dry manufacturing of the building,
C) forming a transport unit on-shore or in-shore,
D) transporting the transport unit in a self-buoyant manner, preferably using tug boats, to the site,
E) attaching one end of the retaining cables to the flotation base and attaching the other end of the retaining cables to the downward impelling means,
F) if applicable, attaching the means for maintaining the lateral position to the construction.
If the floating construction is a floating substructure for a wind turbine comprising a telescopic tower, the installation method according to the present invention comprises the following steps in any technically possible order:
A) manufacturing the flotation base on-shore or in-shore,
B) dry manufacturing the telescopic shaft, including at least one base segment and one head segment,
C) forming a transport unit on-shore or in-shore according to the following sub-steps:
C1) attaching the telescopic shaft in retracted condition to the flotation base,
C2) attaching at least part of the wind turbine means to the head segment,
C3) attaching the extensor arms, if applicable, to the flotation base,
C4) attaching the stays, if applicable, to the flotation base,
C5) attaching the wave energy harness means, if applicable, to the flotation base,
D) transporting the transport unit in a self-buoyant manner, either by using tug boats or by self-propulsion, to the site,
E) attaching one end of the retaining cables to the flotation base and attaching the other end of the retaining cables to the downward impelling means,
F) attaching to the substructure, if applicable, the means for maintaining the lateral position,
G) extending the telescopic shaft.
The wind turbine means (step C2) are preferably attached before step D) self-buoyant transport and before step G) extension of the telescopic shaft, but they may be attached at a different time without departing from the scope of the present invention.
The installation method according to the present invention also comprises before step D) the following step:
H) placing the flotation base on the body of water at the site.
The installation method according to the present invention can also comprise after step D) the following step:
I) ballasting the flotation base to submerge it to the desired depth for the installed condition,
The installation method according to the present invention can also comprise after step C) the following step:
J1) provisionally attaching flotation stabilisers to the floating construction;
in which case the installation method according to the present invention can also comprise after step J1) the following step:
J2) removing the flotation stabilisers from the floating construction.
Said stabilising flotation means can include any such means known in the art, such as floaters, barges or the like. Said stabilising flotation means can be connected to the flotation base and/or the shaft by various systems known in the art, such as attachment cables, launching cables, sliding or guiding elements, etc.
The installation method according to the present invention can also comprise before step E) the following steps:
K1) manufacturing on-shore or in-shore at least one concrete box with the downward impelling means and placing it in the body of water of the site,
K2) transporting said concrete box in a self-buoyant manner, using tug boats, to the site,
K3) ballasting said concrete box such that its total weight increases and it is submerged to its operational depth.
The installation method according to the present invention can also comprise before step E) the following step:
M) placing on the flotation base traction means for the retaining cables;
and then the installation method according to the present invention can also comprise, in section E): actuating said traction means for the retaining cables to adjust the distance between the floating means and the downward impelling means.
In at least one of said steps of the installation method according to the present invention, one or more tug boats can be used to control the surface position of the floating substructure.
Optionally, step G) of the installation method according to the present invention is divided into two or more steps, which are inserted between or performed simultaneously to the other steps of the method. It can include for example one or more steps after step D) and before step I) and one or more steps after step I).
Similarly, step D) of the installation method according to the present invention is preferably divided into two or more steps, including:
As indicated, the order of the steps can be any technically possible order without departing from the scope of the invention. For example, step D) can also be performed after step E), in order to establish all the connections of the retaining cable in port or in-shore conditions.
Finally, if step C2) includes installation on the head segment of only one part of the wind turbine means, the method also comprises after step D) the following step:
N) assembling on the head segment all the wind turbine means.
It must be noted that, by using a special type of substructure designed to provide solutions for a supporting substructure for large capacity turbines, the present invention allows providing a repowerable substructure. That is, a substructure originally designed with an increased capacity and adaptability to allow repowering (subsequent replacement of the original turbine by a new turbine with greater power, efficiency and profitability) using the same substructure.
It must also be noted that the installation method according to the present invention as described above is reversible. That is, the steps performed can be executed in the opposite order to dismantle the construction, in order to remove it completely or to perform work of any type on the structure in port and reinstall it. In addition, when the floating construction is a floating substructure for a wind turbine, the telescopic shaft can be configured to return to the retracted condition at any time of the useful lifetime of the substructure, such as for maintenance actions or for repowering.
The present invention therefore provides a floating construction and a method for installing the same that are advantageous for great depths, particularly applicable to constructions made in part from concrete and with little or no dependence on great maritime means for transporting, handling and hoisting the construction elements, consequently implying a low or null cost associated to said means.
The flotation base according to the present invention can be considered to be analogous to the foundation block of a gravity foundation solution resting on the seabed. However, it is possible to make the flotation base of the present invention with a less complex design if it is not ballasted, as this allows preventing valve mountings for such purpose. Even if it is ballasted, the external and internal pressure differences on the walls of the flotation base are less than those withstood in case of ballasting to the seabed. In addition, the flotation base of the present invention requires a less bulky structure since the efficacy of the gravity foundations with respect to stabilisation are closely linked to their weight, which is normally solved by using large volumes heavily ballasted that must be able to withstand the transmission of high forces to the seabed. These features can allow keeping costs relatively low.
In short, the present invention provides a floating construction and a method for installing the same in offshore waters that are advantageous for great depths, are relatively simple, efficient, safe and economical, both for installation and maintenance, and/or, in the case of floating substructures for wind turbines, repowering.
These and other features and advantages of the present invention will become apparent in view of the following non-limiting description of an embodiment of the invention, made with reference to the accompanying drawings, where:
With reference to the accompanying figures, all of which show a floating construction which, in installed condition, according to the present invention, comprises: a floating base 2, which includes at least one body comprising at least a cavity 25, the maximum horizontal dimension of which is greater than its maximum vertical dimension; a building supported by said flotation base 2; downward impelling means; and at least three retaining cables 8 the corresponding upper ends of which are joined to said flotation base 2 and the corresponding lower ends of which are joined to said downward impelling means. In addition, in all figures except 8 and 11 the building that forms part of the floating construction comprises a telescopic shaft 3 where the wind turbine means 7 shown are an accessory that is optional and/or interchangeable with other accessories, depending on the use of the floating construction, illustrated only by way of example to describe the embodiments of the invention. In
However,
Specifically,
Reference will now be made to
In this embodiment, the floating substructure 1 further comprises lateral means 16 for maintaining the position by which the floating substructure 1 is attached to the seabed. Said lateral means 16 for maintaining the position comprise three moorings, each of which starts at the peripheral area of said flotation base 2 and hangs down away from the flotation base 2 until reaching and resting on the seabed. In this embodiment, each of these moorings is formed by a long and thick chain, and said assembly of chains, or moorings, prevents or at least limits the lateral movement of the floating substructure 1. Alternatively, said moorings can consist of metal or fibre cables, or other types known in the art, without departing from the scope of the invention.
The weight of the massive suspended element maintains the retaining cables taut, which together with the substantially triangular arrangement allows the massive element to move substantially together with the floating base, thereby improving the stabilisation effect.
In this embodiment the retaining cables are designed such that their axis passes approximately through the centre of gravity of the massive suspended element, which improves the behaviour of the assembly as the centre of forces is located near the alignment of said cables. In addition, in this embodiment the retaining cables adopt a sufficient inclination greater than 1 degree, such that the limited inclinations that the floating construction will experience during its operation will not manage to make a retaining cable vertical, which is suitable for preventing slacking phenomena, in which the retaining cables lose tension.
In this embodiment, the floating substructure 1 further comprises lateral means 16 for maintaining the position by which the floating substructure 1 is attached to the seabed. Said means 16 for maintaining the lateral position comprise a pile anchored to the seabed and a single mooring attached on one end to the common box 13 and on the other end to said pile. As indicated above, the interior of the common box 13 is completely filled with a specific mixture of ballast materials, such that the flotation base 2 is placed at its operational depth, such that the lateral means 16 for maintaining the position are not intended or designed to provide a downward impelling means in order to determine the depth of the floating substructure 1; instead, they only withstand the tensions caused by forces exerted on the floating substructure 1 by external actors, such as waves, sea currents, etc. In any case, the means for maintaining the lateral position can exert certain downward forces that contribute to stability, together with that exerted by the downward impelling means, without departing from the scope of the present invention.
In this embodiment, the floating substructure 1 further comprises lateral means 16 for maintaining the position by which the floating substructure 1 is attached to the seabed. Said lateral means 16 for maintaining the position comprise three moorings (of which only two are visible due to the view shown), each of which starts at a corresponding extensor arm 19 and hangs downward away from the flotation base 2 until resting on the seabed. In this embodiment, each of these moorings is formed by a long and thick chain, and said assembly of chains, due to their weight, prevents or at least limits the lateral movement of the floating substructure 1.
In addition, the floating substructure 1 includes three stays 20 each of which starts at a corresponding extensor arm 19 and is joined by its other end to the upper end of the base segment 4 of the shaft of the floating substructure 1. In fact, in this embodiment three strands are provided, each of which is attached on one end to the common box 13 and on the other end to the upper end of the base segment 4 of the shaft of the floating substructure 1. Each of said strands passes through a deflection element 21 placed at the free end of a respective extensor arm 19, such that each strand is divided into a bottom segment reaching from an extensor arm 19 to the common box 13 and an upper segment that extends from an extensor arm 19 to the upper end of the base segment 4 of the shaft of the floating substructure 1. Then each of said lower segments forms each of said retaining cables 8, and each of said upper segments forms each one of said stays 20. Said deviation element 21 in this embodiment is a plastic element with a curved face that allows the cable to deflect, adopting a suitable bending radius.
In this embodiment, the floating substructure 1 further comprises lateral means 16 for maintaining the position by which the floating substructure 1 is attached to the seabed. Said means 16 for maintaining the lateral position comprise a pile anchored to the seabed and a single mooring attached on one end to the common box 13 and on the other end to said pile. As indicated above, the interior of the common box 13 is completely filled with a ballast material 14, such that the flotation base 2 is placed at its operational depth, and such that the lateral means 16 for maintaining the position are not intended or designed to provide a downward impelling means in order to determine the depth of the floating substructure 1; instead, they only withstand the tensions caused by forces exerted on the floating substructure 1 by external actors, such as waves, sea currents, etc.
In addition, the floating substructure 1 includes three stays 20 each of which starts at a corresponding extensor arm 19 and is joined by its other end to the upper end of the base segment 4 of the shaft of the floating substructure 1. Preferably, the stays 20 are pre-installed, that is, one end of each stay 20 is attached either to the floating base or to the upper end of the base segment 4 of the shaft of the floating substructure 1 before the transportation step, while the rest of the stay 20 is folded and attached to the floating substructure. After the transportation step, each stay 20 is extended and attached on its opposite side either to the upper end of the base segment 4 of the shaft of the floating substructure 1 or to the floating base, respectively.
Reference is now made to
With reference specifically to
In fact, once the transportation step shown in view 6(a) has finished and before the equilibrium condition shown in view 6(b) is reached, the common box 13 is partially ballasted with a first ballast material 14 until said cables are fully extended.
View 6(b) then shows the transport unit 9 in said equilibrium condition, with the cables fully extended, and the common box 13 suspended at a certain distance from the seabed, corresponding to its buoyancy point, with the flotation base 2 floating on the water.
Then, prior to the installed condition shown in view 6(c), lateral means 16 for maintaining the position are attached to the floating substructure 1 by which the floating substructure 1 is anchored to the seabed. Said lateral means 16 for maintaining the position comprise two moorings, each of which starts at the peripheral area of said common box 13 and hangs down away form said common box 13 until resting on the seabed. In this embodiment, each of these moorings is formed by a long and thick chain attached to an anchor on the seabed, and said assembly of chains prevents or at least limits the lateral movement of the floating substructure 1. Alternatively, said means 16 for maintaining the position can be connected to the floating substructure 1 before ballasting the suspended massive element, or can be connected to a different part of the floating substructure 1 such as the flotation base 2.
The common box 13 is then fully ballasted using a second ballast material 14, such that the flotation base 2 is lowered to its operational depth, compressing the air trapped in the central lower recess of the flotation base 2.
View 6(c) shows the floating substructure 1 according to the present invention in said installed condition, where the cables are fully extended and under tension, the common box 13 is fully ballasted so that the flotation base 2 is at its operational depth, and the lower central recess in the flotation base 2 contains a compressed air chamber 22 that can increase the buoyancy experienced by the flotation base 2. Regulating the air contained in said chamber 22 can allow regulating the buoyancy force and therefore the depth of the floating substructure assembly 1. This embodiment also incorporates a Wells type turbine 23 in an air passage between said compressed air chamber and the interior enclosure of the shaft, such that the variations in the water depth of said chamber 22 caused by waves can be used to generate power.
In this case the shaft of the floating substructure 1 is emerged and the flotation base 2 is semi-submerged.
With reference specifically to
Optionally, the transportation unit 9 and the massive element in the form of a concrete box 13 can be transported joined and/or with the connections of the two ends of at least part of the retaining cables 8 already established.
View 7(c) shows a later step of the installation process in which the retaining cables 8 transported on the massive element have been extended to different lengths, in full or in part, and connected to peripheral points of the flotation base 2.
View 7(d) shows the ballast process of the concrete box 13, which leads to its gradual fall until it is finally suspended from the retaining cables 8. The weight of the box 13 and the retaining cables 8 that hold it will make the box 13 tend on its own towards its final position with respect to the flotation base 2, which in this case coincides with the central vertical axis 10 of the shaft and of the flotation base 2. However, the process can also be aided by one or more tug boats 28.
Once the box 13 is suspended from the flotation base 2 by inclined retaining cables 8, the structure will have a great stability and the telescopic shaft 3 will be raised together with the wind turbine means 7, as shown in view 7(e). Finally, view 7(f) shows the installed condition of the floating substructure 1 with the box 13 fully ballasted and the incorporation of means 16 for maintaining the lateral position. In this case the flotation base 2 is ballasted partially to adjust the depth of the structure. The ballast material 14 is preferably liquid and its volume adjustable, allowing to adjust as required the depth of the assembly according to circumstances, particularly wind and waves.
In the embodiment according to the invention of
In the embodiment of
In turn, in the embodiment of
The floating substructure 1 of this embodiment also comprises three stays 20, each of which arise from each one of the additional hollow bodies and are joined to the upper end of the base segment 4 of the shaft of the floating substructure 1. Preferably the lower end of a stay 20 of a floating construction according to the present invention will be joined to the flotation base 2 of the floating structure at a position close to or aligned with the point of union of the upper end of one of the retaining cables 8 to the flotation base 2.
In this embodiment the segments of the telescopic shaft 33 are formed by prefabricated half-segments which, joined at vertical joints 38, form cylindrical segments of the shaft. Similarly, formed between said cylindrical segments are horizontal joints 37 along the shaft.
The tower segments formed by half-segments can be preassembled in dry dock and/or in port to form full segments, and then the full segments attached to the flotation base 2, as an intermediate step also applicable to other offshore substructures that use telescopic towers such as that described in the present invention.
Lastly,
More specifically, the peripheral wall of the flotation base 2 is extended downward such that a cavity facing downward is defined. This cavity initially contains air which is trapped when the flotation base 2 is placed in the body of water of the site. In addition when the flotation base 2 is submerged said trapped air is compressed, forming said pressurised gas chamber 22. Alternatively or additionally, air or any other pressurised gas can be introduced in said pressurised gas chamber 22. In addition, the flotation base 2 is compartmentalised. Each compartment has an opening in the end wall and, in corresponding with each such opening, a Wells type turbine 23. In addition, the compartments also have an opening in each partition wall between compartments. The partitions between compartments also extend downward such that said pressurised gas chamber 22 is also compartmentalised.
The power generation system of a Wells type turbine 23 is based on OWC (oscillating water column) technology, which relies on the pressure changes generated by waves on the air chamber 22 that drive air through the Wells type turbines 23.
The presence of Wells type turbines 23 in the embodiments of the present invention to generate power from waves in which the floating construction is a floating substructure 1 for a wind turbine is particularly appropriate as all the infrastructure provided for evacuating the power generated by the wind turbine is already present.
In addition, the pressurised gas chamber 22 can comprise means for controlling and regulating the volume and/or pressure of the gas contained in said pressurised gas chamber 22, in order to regulate or help regulate the depth of the floating substructure 1 and to adjust or help adjust the resonant frequency of the gas chamber 22 to improve the efficiency of the oscillating water column system.
With reference again to
joining a first long and thick chain by one of its ends to a first peripheral point of said flotation base 2 such that said chain is extended, moving away from the flotation base 2 until it rests on the seabed, and
joining a second long and thick chain by one of its ends to a second peripheral point of said flotation base 2 such that said chain is extended, moving away from the flotation base 2 until it rests on the seabed,
said first and second peripheral points being placed diametrically opposite each other with respect to the flotation base 2; and
As shown in
Said first working area is a sheltered area with a great depth.
This embodiment also incorporates hydrodynamic damping means 39 in the form of substantially vertical elements attached laterally to the side of the massive element. Said elements interact with the water surrounding the massive element and reduce its horizontal movement, increasing its contribution to the stability of the floating construction. Said substantially vertical elements can have the form of a plate or solid wall, preferably made from concrete or metal, or in the form of a laminar element as a sail made from fibre materials, textiles or other materials known in the art.
Other types of hydrodynamic damping can also be used without departing from the scope of the invention, even those based on growth of algae or other organisms in the suspended massive element, and/or other means known in the art that enhance friction and/or mobilisation of the water that surrounds said massive suspended element.
This embodiment also shows that the retaining cables are designed such that two ends of different retaining cables start at approximately the same point, allowing a perfect triangulation of the cables and therefore a more rigid behaviour of the connection between the flotation base and said massive element. Said triangulations can be generated in a horizontal and in a vertical sense (as shown in the figure), in order to rigidify the union between the two elements against torsion (that is, rotations about the vertical axis of the floating construction).
Naturally, the principal of the present invention remaining the same, the embodiments and constructive details may vary considerably from those described and represented for illustration purposes and in a non-limiting sense, without departing from the scope of the present invention as defined in the accompanying claims.
For example, by way of illustration, in light of the teachings of this document it would be obvious for a person skilled in the art that the turbine means could comprise up-wind or down-wind turbines, as well as any number of blades, not being limited to three blades as shown for illustration purposes.
Also for purposes of illustration, although the present document refers to “cables” used to connect the downward impelling means and the flotation base, a person skilled in the art will understand that instead of cables these can be chains, rods, slings or the like, without departing from the scope of the invention.
Also for purposes of illustration, a person skilled in the art in view of the teachings of the present document will find it obvious that the lateral extensions referred to herein as “arms” can be coupled or even integrated in a lateral extension in the form of a continuous crown or as crown arcs, or in any other type of structure, without departing from the scope of the invention. Similarly, it will be obvious for a person skilled in the art in view of the teachings of the present document that although circular shapes are preferred for many of the elements comprised in the invention such as the shafts, hollow bodies or boxes, many other shapes are possible without departing from the scope of the invention, such as square or rectangular shapes, or regular and irregular polygons.
Known techniques may be used to regulate the volume and/or weight of the ballast material of the massive elements, such as those used in submarines to control depth.
This is a U.S. national phase of International Patent Application No. PCT/ES2015/070412, filed on May 27, 2015. Priority under 35 U.S.C. § 119(a) and 35 U.S.C. § 365(b) is claimed from Spanish Patent Application No. P201430794, filed on May 27, 2014.
