The present invention relates to a support base for an offshore structure, particularly adapted to provide generation of renewable energy.

BACKGROUND ART

Different types of bases for supporting offshore structures are known. Two main types are fixed bases and floating or buoyant bases. Fixed bases normally comprise one or more rigid supporting structures (e.g. legs) anchored to the seabed. With respect to floating or buoyant bases, several configurations have been proposed: many of these employ floater elements in the form of hollow floater tanks that in use are arranged substantially below the mean sea level and provide a buoyancy force to support the offshore structure. Ballasts in the floater and/or mooring lines anchored to the seabed may be provided for achieving stability.

A particular conventional support base is typically designed to satisfy the main purpose of supporting with certain stability a particular type of offshore structure. For example, a conventional base for supporting an offshore wind turbine is normally quite different from a conventional base for supporting an oil plant. Moreover, incorporation of other functionalities different from stably supporting the offshore structure may require very significant changes in the corresponding design of such a support base.

Oscillating Water Column (OWC) wave power plants are known. In these wave power plants, the rising and falling water surface within a chamber is used to produce an oscillating air current in which a turbine is placed. In general, a so-called Wells turbine is used to take advantage of the air flow in two directions. A generator may be operationally connected to the turbine in order to generate electricity. Incorporation of an OWC system to a base for supporting an offshore structure may be very interesting, since electricity generated by the OWC system could be easily supplied to the supported offshore structure for its consumption. For example, a lighthouse could use electricity from the OWC system for supplying the corresponding light systems, a wind turbine could use electricity from the OWC system for supplying auxiliary systems such as e.g. light systems, yaw systems, pitch systems, an oil plant could use electricity from the OWC system to illuminate the plant, etc. Systems comprising a base supporting one or more offshore structures and an OWC system integrated in said base are known. However, these known systems are limited to support a particular type of offshore structures. For example, GB2365385A and GB2442719A disclose respective systems restricted to offshore wind turbines. The design of said systems would have to be changed significantly in order for it to support other types of offshore structures, such as e.g. oil plants, bridges, etc.

US2012248776 A1 discloses an offshore platform including a support structure for supporting a workstation in a body of water at an offshore location; the support structure having a mounting formation, and at least one duct mounted to the mounting formation, the duct being configured to receive an oscillating water column (OWC) from the body of water wherein oscillations of the OWC generate a fluid flow for driving an energy extraction module. In particular, embodiments of the platform are described having columns (or pylons), all or some of said columns having a plurality of ducts mounted about the column (i.e. externally to the column). Each duct is configured to receive an OWC from the ocean. The OWC oscillates in response to the rise and fall of ocean waves passing the duct. The abovementioned arrangement of the ducts with respect to the corresponding column (or pylon) may cause the overall OWC system to be significantly exposed to the force/impact of waves and currents which may lead to additional loads and instabilities because of the OWC system. Moreover, the turbines of the OWC system are relatively unprotected. These inconveniences may cause significant wear/damages on at least some OWC elements and possibly on the offshore platform as a whole and accordingly reduce the life of the OWC system.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a versatile support base suitable to at least partially support a wide range of types of offshore structures while at least partially resolving some of the aforementioned problems.

In a first aspect, a support base for at least partially supporting an offshore structure is provided, the support base comprising an inner space, a divider piece, a tubular pylon, a lid and one or more holes. Each hole defines a water inlet of an oscillating water column system. The divider piece is provided in the inner space. The divider piece has a top wall and one or more inner side walls defining a water oscillating chamber connected with each water inlet of the oscillating water column system. The tubular pylon and the lid are arranged in such a way that a turbine chamber is defined on top of the water oscillating chambers.

A modular built-up of a support base for an offshore structure is thus provided. The combination of the divider piece and inner space (into which the divider piece is inserted) permits having OWC chambers which are relatively well protected from the outside environment. The tubular pylon and the lid may allow easily forming a turbine chamber with ensured protection of turbines (and possibly generators and/or other electrical components arranged with said turbines) from the offshore environment. The OWC portion of the support base may be sealed off from the rest of the structure. For example, flow of moist air into a wind turbine or lighthouse may thus be avoided. An aspect of this invention is that the proposed support base may be easily used to integrate OWC functionalities with support of different types of offshore structures, such as e.g. wind turbines, houselights, oil plants, bridges, etc. Of course, depending on the type of offshore structure to be supported, more than one support bases of the suggested type may be used. For instance, an oil plant may require several support bases of this type. In any case, the suggested support base may be considered a versatile support structure of general purpose in the sense of that the same type of supporting structure may be used to support different types of offshore structures in a very simple way.

Another aspect may be that electricity generated by the integrated OWC system may be easily supplied to the supported offshore structure. This way, an offshore structure supported by a support base according to the invention could possibly be stand-alone. For example, an offshore lighthouse could use OWC electricity to produce the corresponding lighting, an offshore oil plant could use OWC electricity to illuminate the plant, an offshore bridge could use OWC electricity to illuminate the bridge, etc.

Still another aspect may be that the integrated OWC elements can cause extension of the useful life of the support base. Part of the kinetic and potential energy of the waves is redirected and transformed into electricity by the integrated OWC system. Therefore, the support base does not assume the whole energy impact of the waves, since part of this energy is captured and converted into electricity by the OWC system. This may increase the lifetime of the support base and/or may reduce the need of material in the support base. In some embodiments, the inner space may have a substantially cylindrical shape. This implies that pieces to be inserted (totally or partially) into this inner space will have rounded shapes, which may be considered suitable according to structural, stability and manufacturing reasons.

According to embodiments of the invention, respective longitudinal axes of the inner space and the overall support base may substantially coincide, such that the inner space is provided in a central position of the support base. This central position may permit better stability of the overall structure.

In embodiments of the invention, the top wall of the divider piece (defining the water oscillating chambers) may comprise a hole defining a top opening for each of the water oscillating chambers. This way, the structure may be quite prepared to receive corresponding turbines to generate electricity from the air flows coming from the water oscillating chambers. In this sense, embodiments of the support base may incorporate a corresponding turbine on each top opening of the water oscillating chambers. The turbines may thus be integrated in the support base.

In accordance with embodiments of the invention, the inner side walls of the divider piece (defining the water oscillating chambers) may be configured with a thickness and orientation causing each water oscillation chamber to have a substantially uniform horizontal separation along the height of the divider piece.

Alternatively to having said substantially uniform horizontal separation, the inner side walls of the divider piece may be configured with a thickness and orientation causing each water oscillation chamber to have a horizontal separation substantially decreasing upwardly. This may permit the air flows caused by oscillating water motions in the water oscillation chambers to be stronger, such that electricity production may be more efficient. In embodiments of the invention, the inner side walls of the divider piece may be provided substantially vertical. Alternatively, the inner side walls of the divider piece may be provided substantially inclined in alignment with the inclination of the water inlets. This aligned inclination of the inner side walls may permit improved oscillating motions of the water entering and exiting the water inlets. In some embodiments, the tubular pylon may comprise a bottom region fitted in a groove of the inner space around the divider piece. This fitting may permit a strong and stable assembly of the tubular pylon with the support base, possibly needing very few additional fastening means (e.g. screws). In embodiments of the invention, the tubular pylon may comprise inner protuberances for supporting the lid in a position internally of the tubular pylon, such that an upper region of the tubular pylon is defined above the lid. Taking this into account, a leg or tower of the offshore structure (to be supported) may be fitted in said upper region of the tubular pylon. This other fitting may permit a strong and stable assembly of the leg or tower of the offshore structure with the support base, possibly needing very few additional fastening means (e.g. screws).

In some embodiments, the tubular pylon may comprise one or more holes, each hole defining an opening to the outside for the turbine chamber, with the goal of promoting air flows to be transformed into electricity by the corresponding turbines. According to embodiments of the invention, the lid may have a substantially inverted conical shape, which may aerodynamically optimize the air flows to be transformed into electricity.

According to some embodiments, the support base may comprise a substantially inverted conical region which comprises the inner space and the one or more holes defining the one or more water inlets. Embodiments of the support base may further comprise a substantially non-inverted conical region which supports the inverted conical region. The inverted conical region and/or the non-inverted conical region may perform the function of breakwater. In this respect, a non-inverted conical region is to be understood as a region with a decreasing cross-sectional area from a bottom towards a top. An inverted conical region is to be understood as a region with an increasing cross-sectional area from a bottom towards a top.

In further embodiments of the invention, the support base may further comprise an intermediate substantially cylindrical region between the inverted conical region and the non-inverted conical region, such that the non-inverted conical region supports the inverted conical region through said intermediate cylindrical region. This feature may allow avoiding or reducing stress concentrations due to the action of water motions on the support base.

Alternatively to having the abovementioned non-inverted conical region, the support base may have a mono-pile structure, and/or a tripod structure, and/or a gravity base structure, and/or a caisson structure, and/or a Tension Leg Platform (TLP) structure.

In any of the embodiments explained, diverse pieces/regions may be separate pieces which can be easily assembled. For example, in some "conical" configurations, the inverted conical region and the non-inverted conical region may be separate pieces (and, optionally, the intermediate cylindrical region), such that they can be transported separately. This may permit an easier/cheaper transport of the support base. If the support base is aimed at resting on the seabed, having separate pieces may permit designing some pieces (e.g. the non-inverted conical region) with different heights, and some other pieces (e.g. the inverted conical region) may be standardized according to a particular design, as well as both pieces may have corresponding standard coupling parts (optionally comprising e.g. the intermediate cylindrical region). This way, the standard piece could be coupled with another piece having a height depending on the depth of the sea area where the support base is to be installed. BRIEF DESCRIPTION OF THE DRAWINGS

Particular embodiments of the present invention will be described in the following by way of non-limiting examples, with reference to the appended drawings, in which:

Figure 1 schematically illustrates a front view of a support base according to a first embodiment of the invention;

Figure 2 schematically represents a cross-sectional view of a support base according to a second embodiment of the invention;

Figure 3 schematically illustrates a perspective view of the support base of Figure 2 but disassembled;

Figure 4 schematically represents an exploded view of the divider piece of Figure 3;

Figure 5 schematically represents a perspective view of an alternative divider piece;

Figures 6 to 9 schematically represent different types of offshore structures supported by one or more support bases according to embodiments of the invention; and

Figures 10 to 14 schematically represent different types of support bases according to other embodiments of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be understood by one skilled in the art however, that the present invention may be practiced without some or all of these specific details. In other instances, well known elements have not been described in detail in order not to unnecessarily obscure the description of the present invention. Figure 1 schematically illustrates a front view of a support base according to a first embodiment of the invention. This support base 100 comprises a substantially inverted conical region 102 at least partially supporting the offshore structure (not shown), and a substantially non-inverted conical region 101 supporting the inverted conical region. The support base 100 further comprises an intermediate substantially cylindrical region 103 between the inverted conical region 102 and the non-inverted conical region 101 , such that the non-inverted conical region 101 supports the inverted conical region 102 through said intermediate cylindrical region 103.

In this particular case, the non-inverted conical region 101 may be considered as a foundation and the inverted conical region may be considered as a transition piece (between the foundation and at least part of the offshore structure), such that the transition piece is supported by the foundation (through the cylindrical region 103, in this example). In other embodiments, shapes other than conical shapes may be considered for any of the foundation and the transition piece.

The inverted conical region 102 comprises one or more holes 104, each hole defining a water inlet 104 of an oscillating water column system. And the inverted conical region comprises an inner space (not shown) and a divider piece (not shown) provided in the inner space, said divider piece defining a water oscillating chamber (not shown) connected with each water inlet 104 of the oscillating water column system.

Figure 1 further shows a base piece 106 supporting the non-inverted conical region 101 . This base piece 106 may have a more pronounced conical configuration which may permit a better stabilization of the overall support base 100 in case of the support base 100 being aimed at resting on the seabed. If the support base is required to float in the sea, this base piece 106 can be suitably ignored. Optionally, the support base 100 may further comprise an upper substantially cylindrical region 105 provided on top of the inverted conical region 102, such that the inverted conical region 102 may at least partly support the offshore structure in combination with this additional upper cylindrical region 105.

The offshore structure may be fixed on top 108 of said upper cylindrical region 105 or (if such a region 105 does not exist) on top of the inverted conical region 102 by using conventional fastening means, such as e.g. screw based assemblies. However, the next two figures describe a preferred configuration based on nesting pieces which provides good subjection and stability by taking advantage of the weight of said pieces themselves and of the supported offshore structure.

Figure 2 schematically represents a cross-sectional view of a support base according to a second embodiment of the invention. This figure further shows a divider piece provided in an inner space of the inverted conical region 102, said divider piece having a top wall 203 and one or more inner side walls 205 defining a water oscillating chamber 206 connected with each water inlet 104 of an oscillating water column system. Each water oscillating chamber 206 is connected with its corresponding water inlet 104 in such a way that an oscillatory motion 210 of water entering and exiting the water inlet 104 is caused. In this particular example, the divider piece (defining the water oscillating chambers 206) is provided with a bottom wall 202 which may be configured to properly align each water inlet 104 towards its corresponding water oscillating chamber 206. This bottom wall 202 may also have the function of sealing the water oscillating chambers 206.

The top wall 203 of the divider piece (defining the water oscillating chambers 206) comprises a hole defining a top opening for each of the water oscillating chambers 206. A turbine 207 may be provided on each of said holes defining a top opening for each of the water oscillating chambers 206. This support base 100 further comprises a tubular pylon 214 and a lid 209 arranged in such a way that a turbine chamber 21 1 is defined on top of the water oscillating chambers 206. The tubular pylon 214 comprises a bottom region 204 fitted in a groove around the divider piece (defining the water oscillating chambers 206). The tubular pylon 214 also comprises inner protuberances 212 for supporting the lid 209 in a position internally of the tubular pylon 214, such that an upper region 210 of the tubular pylon 214 is defined above the lid 209. Taking this into account, a leg or tower of the offshore structure may be fitted 213 in said upper region 210 of the tubular pylon 214.

The lid 209 may have a substantially inverted conical shape. The tubular pylon 214 may further comprise one or more holes 208, each of said holes 208 defining an opening to the outside for the turbine chamber 21 1 .

Figure 3 schematically illustrates a perspective view of the support base of Figure 2 but disassembled. Figure 3 shows a perspective view of the inner space 300 of the inverted conical region 102 in which the divider piece 302 (defining the water oscillating chambers 206) is provided. This inner space 300 is shown as a cylindrical hole in a central position of the inverted conical region 102. An inner surface of this cylindrical hole 300 is indicated by reference number 204.

This figure also shows the divider piece 302 isolated from the rest of the support base 100. This perspective view of this divider piece 302 shows the top wall 203 with a hole 301 defining a top opening 301 for each of the water oscillating chambers 206. Respective turbines 207 to be positioned on each of said holes 301 are also shown. Both the inner space 300 and the divider piece 302 are designed to cause a groove 306 between the divider piece 302 and the inner surface 204 of the inner space 300, once the divider piece 302 has been (not snugly) fitted in the inner space 300.

Figure 3 also shows the tubular pylon 214 with three differentiated regions indicated: the bottom region 305 to be fitted in the previously mentioned groove 306, the upper region 303 above the lid 209 once the lid 209 has been properly mounted in the tubular pylon 214, and the intermediate region 304 defining a turbine chamber in combination with the top wall 203 of the divider piece 302 and the lid 209 once mounted. An important aspect of fitting the bottom region 305 of the tubular pylon 214 in the groove 306 is that a nesting configuration between the inner space 300, the tubular pylon 214 and the divider piece 302 results. The weight of said three (snugly) nested pieces themselves and, further, the weight of the supported offshore structure, allows this nested configuration to provide good support and stabilization (possibly requiring very few additional fastening means). Moreover, this nesting configuration also provides some main parts of an OWC system, so the nested pieces of this configuration have a double purpose (support and OWC) whose combination may be very interesting as argued hereinbefore.

Figure 4 schematically represents an exploded view of the divider piece 302 defining water oscillation chambers of Figure 3. Figure 4 shows the top wall 203 with three holes 301 a-301 c and two differentiated regions 203a-203b, three inner side walls 205a-205c, and the bottom wall 202 with two different regions 202a-202b. The region 203a of the top wall 203, the inner side walls 205a and 205b, and the region 202a of the bottom wall 202 define the water oscillating chamber 206a having the top opening 301 a. The chamber 206b is defined by corresponding inner walls 205b, 205c, top region 203b and bottom region 202b, said chamber 206b having the top opening 301 a. Similarly, a third chamber (not shown) is also defined by corresponding inner walls 205a, 205c, a region of the top wall (not indicated) and a region of the bottom wall (not shown), said third chamber having the top opening 301 c. Figure 4 shows the inner side walls 205a-205c vertically oriented and having a uniform thickness 400a, 400b along the height 402 of the divider piece 302. These vertical orientation and uniform thickness 400a, 400b causes each water oscillation chamber 206a, 206b to have a horizontal separation 401 substantially uniform along the height 402 of the divider piece 302.

Alternatively to this uniform thickness, the inner side walls 205a-205c may have a thickness substantially increasing upwardly. This means, in the particular example of Figure 4, that the thickness 400a could be less than the thickness 400b. This thickness substantially increasing upwardly causes each water oscillation chamber 206a, 206b to have a horizontal separation 401 substantially decreasing upwardly. As already commented, Figure 4 shows the inner side walls 205a-205c provided substantially vertical, but, in alternative embodiments, the inner side walls are not necessarily vertically. A particular example of these alternative embodiments is described below with reference to the next figure. Figure 5 schematically represents a perspective view of an alternative divider piece. This alternative divider piece is similar to the one illustrated by Figure 4. The only difference is that the inner side walls 205a-205c of the divider piece 302 are provided substantially inclined in accordance with the inclination of the corresponding water inlets (not shown because they are comprised in the inverted conical region).

In this case, the inclined inner side walls 205a-205c may also have uniform thickness along the height of the divider piece 302 or, alternatively, the inclined inner side walls 205a-205c may have a thickness substantially increasing upwardly. Details explained with respect to Figure 4 about uniform or increasing upwardly thickness may also be applicable to the example shown in Figure 5. Figure 6 schematically represents an offshore wind turbine supported by a support base according to embodiments of the invention. In particular, this figure shows a wind turbine 600 having a tower 601 supported by a support base 100 according to e.g. the embodiments previously described with reference to figures 2 to 5. A bottom portion of the tower 601 is shown fitted 213 in the upper portion 303 of the tubular pylon 214. See figures 2 and 3 for detailed descriptions about said fitting. Figure 7 schematically represents an offshore oil plant supported by four support bases according to embodiments of the invention. In particular, this figure shows an oil plant 600 having four legs 701 a-701 d supported by corresponding support bases 100a-100d according to e.g. the embodiments previously described with reference to figures 2 to 5. A bottom portion of the leg 701 a is shown fitted 213 in the upper portion 303 of the tubular pylon 214a. Equivalently, the remaining legs 701 b-701 d of the oil plant 700 are shown fitted 213 in the upper portion 303 of the corresponding tubular pylon 214b-214d. See figures 2 and 3 for detailed descriptions about said fittings. Figure 8 schematically represents an offshore lighthouse supported by a support base according to embodiments of the invention. In particular, this figure shows a lighthouse 800 having a tower 801 supported by a support base 100 according to e.g. the embodiments previously described with reference to figures 2 to 5. A bottom portion of the tower 801 is shown fitted 213 in the upper portion 303 of the tubular pylon 214. See figures 2 and 3 for detailed descriptions about said fitting.

Figure 9 schematically represents an offshore bridge supported by two support bases according to embodiments of the invention. In particular, this figure shows an offshore bridge 900 having two legs 901 a, 901 b supported by corresponding support bases 100a, 100b according to e.g. the embodiments previously described with reference to figures 2 to 5. A bottom portion of the leg 901 a is shown fitted 213 in the upper portion 303 of the tubular pylon 214a. Equivalently, a bottom portion of the leg 901 b is shown fitted 213 in the upper portion 303 of the tubular pylon 214b. See figures 2 and 3 for detailed descriptions about said fittings.

The examples shown by figures 6 to 9 illustrate the versatility of the proposed support base, since different types of offshore structures can be effectively supported while having one or more OWC systems integrated very easily. In any of the described embodiments, at least the non-inverted conical region may be a hollow portion, such that this hollow region may be filled with suitable material (e.g. water, stones, etc.) to increase the weight of the support base. This increased weight may permit the support base to stably rest on the seabed. If the support base is aimed at floating in the sea, this hollow region may be filled or not in accordance with floating requirements. In this case, the non-inverted conical region may be moored to the seabed by conventional mooring systems. Floating requirements may refer to e.g. how the support base has to be partially submerged to cause suitable entering and exiting of water through the water inlets.

Alternatively to the examples shown before, other types of support bases are possible. Figures 10 - 14 schematically show respective views of support bases very similar to the one shown by Figure 3 but having different alternative foundations. Figure 10 shows how the foundation may be a mono- pile foundation 10a. Figure 1 1 shows how the foundation may be a tripod foundation 1 1 a. Figure 12 shows how the foundation may be a gravity base foundation 12a. Figure 13 shows how the foundation may be a caisson foundation 13a. Figure 14 shows how the foundation may be a Tension Leg Platform (TLP) foundation 14a.

Although only a number of particular embodiments and examples of the invention have been disclosed herein, it will be understood by those skilled in the art that other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof are possible. Furthermore, the present invention covers all possible combinations of the particular embodiments described. Thus, the scope of the present invention should not be limited by particular embodiments, but should be determined only by a fair reading of the claims that follow.