Dense fluid for a ballast

Abstract

Dense fluids for use in offshore applications are disclosed, such as wind turbine platforms, oil and gas platforms, gravity anchors, catenary weights, and other gravity-based structures. The dense fluid can be mixed with a low-density fluid and high-density solid particles to form a medium-dense fluid. The medium-dense fluid is mixed with medium-density solid particles having the same density as the medium-dense fluid to form a dense fluid with a desired target density. The dense fluid can be produced cost-effectively by selecting medium-density particles that are abundant and can be obtained inexpensively.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application is a continuation - in - part of U.S. Patent Application No. 17 / 068,801, entitled "Pumped Hydro Energy Storage System and Method", filed on October 12, 2020. This application is also a continuation - in - part of U.S. Patent Application No. 18 / 096,127, entitled "Pumped Hydro Energy Storage System and Method, including Fire Extinguishing Features", filed on January 12, 2023. This application also claims the benefit of U.S. Provisional Application No. 63 / 391,330, filed on July 22, 2022. All disclosures are incorporated herein by reference for all purposes.

[0002] The present disclosure generally relates to offshore wind turbines and other floating structures, as well as gravity - based structures. In particular, the present disclosure relates to using dense fluids in the ballast for offshore wind turbines, other floating structures, and gravity - based structures to provide a cost - effective solution. Further, the ballast and structures can be easily recovered from the seabed or the bottom of a lake and estuary.

Background Art

[0003] Global warming has created a major concern for the long - term viability of the planet. The main cause of global warming is the generation of greenhouse gases including water vapor, carbon dioxide (CO2), methane, nitrous oxide, and chlorofluorocarbons (CFCs). A major cause of CO2 emissions into the Earth's atmosphere is the combustion of fossil fuels. Fossil fuels are used in many applications, including power generation.

[0004] In order to mitigate global warming, the movement towards green energy has increased. One type of green energy is to generate electricity using wind turbines. As a result, numerous wind farms have emerged both on land and at sea. For example, as of 2022, the capacity of the world's offshore wind turbines is approximately 64.3 gigawatts (GW). Offshore wind turbines in the sea, lake, or large water masses are more efficient due to the higher wind speeds at sea.

[0005] However, currently, offshore wind turbines generate only a small portion of the total electricity generation due to their higher cost compared to onshore wind turbines. This is because the foundation of offshore wind turbines is fixed to the seabed such as the sea or lake, which significantly increases the cost. Furthermore, as the location of the wind turbine is in a deeper place, the cost becomes higher.

Summary of the Invention

Problems to be Solved by the Invention

[0006] From the above considerations, it is desirable to provide a cost-effective method for generating electricity using offshore wind turbines.

Means for Solving the Problems

[0007] Cost-effective offshore wind power generation is disclosed. One embodiment relates to a semi-submersible platform. The platform includes at least three elongated hollow columns, a floating frame for fixing these hollow columns together to form a polygon, and a dense fluid contained in the hollow columns. The dense fluid is configured to float the columns. A plurality of hollow columns containing the dense fluid are fixed together to form a floating unit of the semi-submersible platform. The use of dense fluid as ballast can make the volume of the hollow columns smaller compared to the use of seawater as ballast. In another embodiment, a gravity anchor, or other types of gravity bottom structures.

[0008] Another embodiment relates to a method of generating electricity. The method includes the step of installing an offshore wind turbine platform on a body of water. The wind turbine platform includes a floating unit having at least three elongated hollow columns, a floating frame for securing these hollow columns together to form a polygon, and a dense fluid contained within the hollow columns. The dense fluid is configured to float the columns. By using the dense fluid as ballast, the volume of the hollow columns can be made smaller compared to using seawater as ballast. A wind turbine unit is disposed on the floating unit. The wind turbine unit is configured to generate electricity using wind to turn the rotor assembly of the wind turbine unit. The electricity generated by the wind turbine unit is sent to an onshore substation.

[0009] Yet another embodiment relates to a gravity anchor. The gravity anchor includes a container having a first opening and a second opening. The openings can be configured to be opened and closed. Dense fluid fills the container and positions the gravity anchor on the sea floor.

[0010] These and other advantages and features of the embodiments disclosed herein will become apparent through the following description and reference to the accompanying drawings. Further, it is understood that the features of the various embodiments described herein are not mutually exclusive and can exist in various combinations and permutations.

[0011] In the drawings, like reference numerals generally refer to the same parts throughout the different figures. Also, the drawings are not necessarily drawn to scale; instead, portions that illustrate the principles of the invention are generally emphasized.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0013] Embodiments for an offshore wind turbine and a ballast filling material using a dense fluid. For example, the dense fluid has a density greater than the density of water or seawater. The density can be varied according to different applications. In the case of a ballast filling material for an offshore wind turbine, etc., the density is from 1.2 g / cm 3 to 3 - 4 g / cm 3 or even in a larger range. For example, the dense fluid can be a low-density dense fluid such as about 1.2 g / cm 3 for applications where it replaces seawater as a ballast filling material. Using the dense fluid currently being described as a replacement for seawater is advantageous because it does not contain living organisms and thus does not require biocides. In active ballast applications, the dense fluid can be a medium-density dense fluid with a density of about 1.5 - 2.5 g / cm 3 . A high-density dense fluid having a greater density, such as about 2.5 - 3 g / cm 3 or even a greater density, may be used for passive ballast applications. A fluid having a greater density, such as 5 - 7 g / cm 3 or even a greater density, may be used for other applications.

[0014] Dense fluids are described for use as ballast filling materials for ballast in offshore wind turbines, but dense fluids may be used in other applications. For example, dense fluids may be used in semi-submersible platforms, gravity anchors, dead weights for maintaining catenaries, or other types of gravity-based structures for offshore wind or offshore oil and gas applications. Dense fluids may be used in pumped hydro storage applications as described in U.S. Patent Application No. 17 / 068,801, which is hereby incorporated by reference in its entirety. Embodiments also relate to stable and cost-effective dense fluids.

[0015] In one embodiment, a stable dense fluid DF includes the following equation. DF = (P1)d1 + (P2)d2 + (P3)d3 Where d1 = a low-density fluid having a density D1 d2 = medium-density particles having a density D2 d3 = high-density particles having a density D3 P1 = the volume percentage of d1 P2 = the volume percentage of d2 P3 = the volume percentage of d3, and D1 < D2 < D3 is.

[0016] The target density D of DF T is less than the density of D3 and greater than D1. In one embodiment, D T is selected to provide an increased density but is still capable of maintaining fluidity. For example, D T is a density compatible with fluidity. The D of DF T can be, for example, about 1.2 to 7 times the specific gravity of water. For example, DF can be a low-density DF, a medium-density DF, or a high-density DF depending on the application. It may also be useful to provide other densities to DF.

[0017] In one embodiment, d1 can be water. Other types of low-density fluids may also be useful. For example, low-density fluids such as dunite mud may also be useful. For example, water is about 1 g / cm3 has a density (D1). With respect to d3, the high-density solid particles have a density greater than D T . In one embodiment, the high-density particles can have a density D3 of about 4.5 - 5 g / cm 3 . For example, d3 can include barite, magnetite, or a combination thereof. Other types of high-density particles having other D 3S can also be useful. For example, the value of D3 can depend on the application. A larger D T may require d3 to have a larger D3. For example, high-density particles with a larger density, such as lead pellets, steel pellets, tungsten pellets, deteriorated uranium pellets, or a combination thereof, may be used for a larger D TS .

[0018] In one embodiment, (P1)d1 + (P3)d3 produces a medium-density fluid DF I accompanied by a medium density D I . In one embodiment, medium-density solid particles d2 are added to DF I to increase D T to D I . For example, the addition of d2 to DF I produces a DF accompanied by D T . The volume of d2 added to DF I should result in a DF accompanied by D T . The amount of d2 depends on, for example, D I and D T .

[0019] The medium-density particles d2 include, in one embodiment, solid particles (of the same or different types) having a density approximately equal to D2. In one embodiment, d2 is selected to have a D2 that results in d2 having neutral buoyancy in DF I . When the D I of DF I is stable, d2 is selected to have a D2 approximately equal to D I . For example, D2 should be within about ±1 - 5% of D I . Preferably, D2 is D Ishould be within about ±1% of. Therefore, selecting d2 to have neutral buoyancy ensures that when d2 is added to DF I it does not impede the resulting flow of DF.

[0020] In one embodiment, d2 can include dunite, calcite, dolomite, or combinations thereof. For example, d2 can have a density of about 2.8 g / cm 3 . For example, 2.8 g / cm 3 can be used to produce DF with a density about 3 to 4 times the specific gravity of water from DF with a density of 2.8 g / cm 3 . It may also be useful to produce DF with other specific gravities relative to water. Other types of d2 may also be useful. For example, d2 may depend on D I and cost. Preferably, d2 is selected to be relatively low cost compared to d3 based on D I . For larger D I , d3 can be selected based on the requirements of a particular application. TS

[0021] To improve the stability of the solid particles, the solid particles can optionally be coated with a surfactant coating. The surfactant coating can be used to improve the fluidity of DF by preventing aggregation and stabilizing the DF. Other techniques for improving the stability and ease of flow of DF may also be useful. For example, mixing d3 with a mud such as dunite mud having a density of about 1.2 g / cm 3 has been found to be effective in improving the stability of the particles. The particle size in the dunite mud can be 60 μm or less.

[0022] The size of the solid particles can be from about several tens of microns to 1 cm or more in diameter. Other sizes for high-density particles can also be useful. Regarding d2, the size can be about 10 - 100 μm. For example, the diameter of d2 can be about 10 - 100 μm. It is understood that the particles may not be perfectly spherical. Preferably, the size of d2 is about 10 - 60 μm. Regarding d3, in the case of a Bingham plastic, d3 can be up to 1 cm or more. Preferably, d3 can be up to 1 cm in the case of a Bingham plastic. For applications that are not Bingham plastics, the size of d3 can be about 60 μm or less. Other sizes for d2 and d3 can also be useful.

[0023] If the particles are minerals supplied by a mining company, the particles can be of a wide range of sizes, such as from several tens of microns to over 1 cm. If the particles are too large, a process may be carried out to reduce the particle size to improve the flowability of the DF. The reduction of the particle size can be carried out in multiple stages to achieve the desired maximum size of the particles at the last stage. It is understood that d2 and d3 can be processed separately and do not need to have the same final maximum size. In some cases, it is acceptable to have a wide range of particle sizes while maintaining flowability in order to reduce costs. For example, the DF may be configured as a Bingham plastic to ensure that larger particles do not settle.

[0024] As an example, the DF may contain water as d1. As being considered, water has a density of about 1 g / cm 3 For the purpose of simplification, water can be associated with a density of 1 g / cm 3 High-density solid particles d3 are mixed with d1 to produce a medium-density fluid DF I having a density of D I The mixing can be, for example, mechanical mixing similar to that used to form concrete. In one embodiment, d3 is about 5 g / cm 3is selected to have a density. For example, d3 can be barite. Alternatively, d3 can be magnetite. A density of about 5 g / cm 3 Other types of high-density particles having a density may also be useful. It may also be useful to select d3 having other densities. For example, d3 can have a density greater than 5 g / cm 3 . In some embodiments, d3 can have a density less than 5 g / cm 3 .

[0025] In one embodiment, DF I has a D 3 of about 2.8 g / cm I . The medium-density fluid DF I comprises a mixture of dunite mud with a density of about 1.2 g / cm 3 and magnetite having a density of about 5.2 g / cm 3 . In one embodiment, DF I comprises a volume of about 60% dunite mud and a volume of about 40% magnetite, and has a density D 3 of about 2.8 g / cm I to produce DF I . The medium-density solid particles d2 can include dunite. Other types of d2 may also be useful, such as calcite, dolomite, or a combination of d 2S .

[0026] In another embodiment, a larger D TS can be achieved by using d3 with a greater density. For example, d3 can be metal particles such as iron turnings or lead particles. In such cases, a density of 6 to 7 times or more the specific gravity of water can be obtained. Other densities can be achieved by selecting appropriate d1, d2, and d3.

[0027] In one embodiment, DF can be handled by compressed air or its flow can be introduced. For example, the movement of DF can be facilitated by compressed air. Due to the cohesiveness of DF, DF can flow rapidly through a pneumatic circuit system such as pipes and tanks. Empirically, compressed air at a pressure of several bar is used at 4 g / cm3 It has been demonstrated by injecting into the bottom of a 4-inch vertical pipe having a DF with a density of. For example, an air blast pushes the mass without bubbles and carries the DF at a high speed exceeding 1 m / s. For example, the DF flows as an aggregate and can flow using a lower low pressure, such as less than 8 bar.

[0028] Unlike d3, d2 can be selected from readily available low-cost minerals. By using a combination of d2 and d3, D T A lower manufacturing cost can be achieved by manufacturing a DF with.

[0029] As described, a DF system including d1, d2, and d3 is provided. The DF system imparts flexibility. For example, by appropriately selecting d2 and d3 using water or other types of fluids, the desired D T can be achieved based on the application. Further, the components of the system can be selected to achieve a DF with the desired D T while considerably reducing costs. Further, the DF can be handled using compressed air, which not only simplifies and facilitates its application but also has good energy efficiency, making the DF very cost-effective.

[0030] Figure 1 shows a process flow 100 for forming a DF with the desired D T . At reference numeral 110, a low-density fluid is provided. The low-density fluid can be, for example, water. Other types of low-density fluids may also be useful. For example, a low-density fluid such as dunit mud may be used. Dunit mud is composed of, for example, a density of 1.2 g / cm 3 .

[0031] At reference numeral 120, medium-density solid particles d2 are provided. In one embodiment, d2 can have a density of about 2.8 g / cm 3 . It may also be useful to provide other densities to d2. If d2 includes different types of medium-density solid particles, the average density can be about 2.8 g / cm 3 . Different d 2SIt is understood that the change in density, such as within about ±1 to 5%, should not change excessively. Preferably, the change in density of different d 2S should be within about ±1%. For example, the medium density particles d2 can include dunite, calcite, dolomite, or combinations thereof. Other types of d2 particles can also be useful. The medium density solid particles d2 can be larger than the particles of d1 mud, such as from several tens of microns to 1 cm or more. The medium particles may optionally be coated with a surfactant coating. It can also be useful to provide d2 without a surfactant coating.

[0032] High density solid particles d3 are provided at reference numeral 130. For example, d3 can have a density of about 5 g / cm 3 . It can also be useful to provide other densities for d3. The high density solid particles may include different types of d3. The change in density should be, for example, within about ±1 to 5%. Preferably, the change should be within about ±1%. For example, the high density solid particles d3 can include barite, magnetite, or combinations thereof. Other types of d3 particles can also be useful. The high density particles d3 may optionally be coated with a surfactant coating. It can also be useful to provide d3 without a surfactant coating.

[0033] In one embodiment, at reference numeral 140, a medium dense fluid DF I is formed. Forming DF I includes mixing d1 with d3. The mixing can be, for example, mechanical mixing. Other mixing techniques can also be useful. As contemplated, d1 can be water. In another embodiment, d1 can be dunite mud. In one embodiment, d1 is a Bingham plastic, such as dunite mud. Other types of Bingham plastic low density fluids can also be useful. When a Bingham plastic is used, d3 does not need to be coated with a surfactant coating. The medium dense fluid has the density of D I . In one embodiment, D I is about 2.8 g / cm 3 . Other values for D I can also be useful.

[0034] At symbol 150, D I is mixed with d2 to form DF with the desired D T For example, d2 is mechanically mixed with D I In one embodiment, d2 has a density D2 equal to about D I In the case of a Bingham plastic, d2 need not be coated with a tension-active coating. Further, in the case of a Bingham plastic, the solid particles do not exceed the shear stress required to flow. Therefore, the solid particles remain suspended within the DF. Compressed air may be used to flow the DF.

[0035] Figure 2 shows a simplified embodiment of an offshore or floating wind turbine system or wind turbine platform 200. The offshore wind turbine system is configured to be a semi-submersible floating wind turbine system. For example, the system is configured to float on a water mass 211. As shown, the system includes a floating platform or floating module 221 configured to float on water. The floating module is, for example, a semi-submersible module having a lower portion disposed below the water surface 212 and an upper portion disposed above the waterline.

[0036] The floating module is further configured to support a wind turbine module 251. The wind turbine module may be, for example, any conventional wind turbine mounted on the floating module. For example, the wind turbine module includes a wind turbine tower. A nacelle 253 or turbine head is disposed at the upper part of the turbine tower. A rotor blade assembly 254 is attached to the nacelle. The nacelle can house a gearbox assembly, an aerodynamic braking unit, a mechanical braking unit, a turbine power generation unit, and a power transmission unit. It may also be useful to provide other units or subsystems in the nacelle.

[0037] In some embodiments, the nacelle can be a rotating nacelle. For example, the nacelle can be configured to rotate around the axis of the turbine tower. This allows the rotor blade assembly to be rotated into the wind to maximize power generation. Also, the blades 256 of the rotor blade assembly may be configured with pitch adjustment capabilities. For example, the pitch of the blades can be adjusted to maximize power generation. In the case of strong winds, the pitch can be adjusted to ensure that the rotor blade assembly does not rotate excessively. The pitch control of the blades can be, for example, part of an aerodynamic braking unit or an addition to other aerodynamic braking functions.

[0038] Regarding the floating module, the floating module includes a plurality of columns 231 that are fixedly attached together to form a semi-submersible platform for the wind turbine module. The columns, in one embodiment, include ballast for the semi-submersible platform. In one embodiment, as shown, the columns are hollow elongated cylindrical tanks that serve as tanks for floating or ballast. Other forms of elongated tanks that can include ballast may also be useful. The elongated tank can be, for example, cylindrical. Other column shapes may also be useful.

[0039] The floating module includes three columns in one embodiment. It may also be useful to provide more than three columns. For example, the floating module can include from three to five columns. The dimensions of the columns must be sufficient to support the wind turbine module and to serve as ballast tanks for the floating module. The dimensions of the columns can depend on, for example, not only the weight of the wind turbine module and other components of the system but also the number of columns. For example, as the weight of the module configured to support becomes heavier, the required volume becomes larger. The volume can be reduced or increased depending on the number of columns.

[0040] In one embodiment, the columns are fixedly attached together by a platform frame to structurally provide a stable semi-submersible platform that can support the wind turbine module and other components of the offshore wind turbine system. The platform frame may include fixtures that form a truss frame, for example, to fixedly attach these columns together, and may be configured as a truss frame. Other types of platform frames may also be useful. The columns may be configured, for example, in a triangular, square, or pentagonal structure. Other shaped forms may also be useful. For example, the shape may depend on the number of columns. In one embodiment, the columns are configured in a vertical configuration. For example, the length of the columns is configured in a vertical plane that is perpendicular to the plane of the water surface.

[0041] The columns are filled with DF. For example, DF has the formula (P1)d1+(P2)d2+(P3)d3, as already described. The use of DF is advantageous because it allows the use of shorter columns compared to columns filled with water or seawater. For example, the volume of the columns required is smaller than that of columns used for water or seawater. Water or seawater has a density slightly below or above 1 g / cm 3 On the other hand, DF can have a specific gravity that is 2 to 3 times, or even greater than, the specific gravity of water or seawater. Thereby, the volume of the columns can be made proportionally smaller. For example, for a given diameter, the length of the columns can be made proportionally shorter. However, there is a minimum length for the columns. Therefore, the diameter of the columns can be made smaller.

[0042] In some embodiments, the columns can be filled with a low-density DF, such as one with a density of 1.2 g / cm 3 Although the density is low, it is still advantageous for use in water or seawater. For example, since DF does not contain living organisms, it does not require biocides. Also, DF can be moved using compressed air, unlike seawater or water. The use of compressed air requires less energy compared to pumps for seawater or water solutions.

[0043] In one embodiment, the columns of the floating module are in fluid communication with each other. Such a configuration can collectively form active ballast in the columns. For example, fluid-connected columns are configured to form an active ballast subsystem of an offshore wind turbine system. As shown, a flow conduit or pipe 236 interconnects the ballasts. For example, each ballast is interconnected to an adjacent column by a flow conduit. The flow conduit is positioned below the waterline or at least below the height of the DF. Other configurations of the flow conduit may also be useful. The dimensions of the flow conduit must be sufficient to allow for an efficient and effective movement of the DF between the columns. The dimensions of the flow conduit may depend, for example, on the fluid rheology of the DF.

[0044] The upper part of the floating module may include a deck 228. The deck can provide a surface on top of the floating module, for example, to support some of the components of an offshore wind turbine. In some cases, the upper part of the column can function as a deck. For example, the deck may include a plurality of sub-decks formed by the upper parts of the columns. In one embodiment, the wind turbine system may include a ballast control device and an actuator unit 281. The actuator unit includes, in one embodiment, a compressor and a pressure vessel for storing compressed air. The actuator unit is used, for example, to generate compressed air and move the DF within the active ballast subsystem. The ballast control device controls the compressor to selectively inject compressed air into the active ballast system to actively level the system. Also, the deck may include a solar panel and a power storage unit to provide power to operate not only components such as the ballast control device and the actuator unit compressor but also other components that require power.

[0045] In one embodiment, the actuator unit communicates with the column through the upper surface of the column. A valve may be provided to control which column is supplied with compressed air from above. When compressed air is supplied to the selected column, the DF is transferred from that column through the flow conduit to other columns in order to provide active ballasting and level the system. For example, air is injected into one or more columns where the DF is desired to be reduced and discharged from one or more columns where the DF is desired to be increased. An active ballast control device may be used to control the actuator unit based on sensors in order to provide active ballasting. For the application of active ballasting, the upper part of the column may be strengthened to ensure that the column can handle the injection of compressed air.

[0046] By using compressed air, leveling can be achieved within 1 - 2 minutes. Furthermore, by using compressed air for water pumps for water or seawater applications, less power is required. For example, compared to a 30KW pump required for seawater applications, a 7.5KW compressor is sufficient. Therefore, only 25% of the power is required compared to the seawater pump solution.

[0047] In one embodiment, the wind turbine module is disposed on top of one of the columns. The column on which the wind turbine module is disposed can be referred to as the primary column, and the other columns can be referred to as secondary columns. In a preferred embodiment, the floating module comprises three columns, namely, one primary column and two secondary columns. Other numbers of columns for the floating module may also be useful. Due to the weight of the wind turbine column, in the neutral state, the primary column will contain less DF than the secondary columns.

[0048] In another embodiment, the primary column may be disposed in the center of the secondary columns. For example, three or more secondary columns may surround the primary column. In such a configuration, the primary column does not necessarily need to be in fluid communication with the secondary columns. However, it is understood that the primary column and the secondary columns may be in fluid communication. Other configurations of the floating module may also be useful.

[0049] As described, the system of FIG. 2 includes active ballasting. In such applications, the DF filling the columns can be medium density DF. The medium density DF can have a density of about 1.5 to 2.5 g / cm 3 and can have other densities of DF for filling the columns of the active ballasting system can also be useful.

[0050] In another embodiment, the system includes passive ballasting. In the case of passive ballasting, the columns of the floating modules need not be in fluid communication via the flow tubes. This is because in the passive ballasting system, the DF remains stationary. For example, the floating module is composed of DF that levels the system. However, it is understood that the columns of the passive ballasting system may be in fluid communication. In the passive ballasting system, the DF can be high density DF. The high density DF can include a density greater than the density used in the active ballasting system. For example, the high density DF can be about 2.5 to 3 g / cm 3 and other densities for the high density DF used in the passive ballasting system can also be useful.

[0051] In another embodiment, the floating module is configured to replace seawater. For example, the floating module is filled with low density DF. The low density DF has a density of, for example, about 1.2 g / cm 3 In one embodiment, the low density DF is dunitite mud. For example, the low density DF includes a low density fluid d1 that is dunitite mud. Other types of low density DFs can also be useful. In some embodiments, the low density DF can be formulated as follows. DF = (P1)d1+(P2)d2 In one embodiment, d1 is water and d2 is medium density particles. The size of the medium density particles can be, for example, smaller than about 60 μm. The medium density particles can include, for example, dunitite. Other types of fine medium density particles can also be useful.

[0052] An offshore wind turbine platform may be part of an offshore power plant with a number of wind turbine platforms. Electricity generated by the wind turbine platform is sent to an onshore substation for further transmission. For example, the electricity is then sent to a power grid for distribution of electricity for use by end users. In some embodiments, the electricity from the platform may be sent to an offshore substation. The offshore substation then sends the electricity to an onshore substation.

[0053] FIG. 3 shows a simplified embodiment of a catenary mooring system 300 for offshore applications such as a floating platform or a ship, including a floating structure. For example, the floating structure can be an offshore wind turbine platform or an oil and gas drilling platform. The catenary mooring system may be used for other offshore applications, including a single-hull ship and a semi-submersible ship.

[0054] As shown in FIG. 3, the floating structure 300 floats on the upper part 313 of a body of water such as the sea. The floating structure is moored using a catenary 333. For example, the catenary system may include a plurality of catenaries, such as ropes or chains, connected to the floating structure. For example, the first end of the catenary is connected to or extends from the floating structure. For the second end, the second end is configured to be located on the seabed 303 due to the weight of the catenary.

[0055] In one embodiment, a weight 353 is suspended from the catenary. The weight is configured to provide an appropriate tension to ensure proper positioning of the floating structure. The weight is configured to create, for example, an angle of the catenary with respect to the seabed of about 30 to 40°. Other configurations of the catenary tension may also be useful.

[0056] In one embodiment, the weight suspended from the catenary includes a weight container filled with DF. The weight container can be a container in the shape of a rectangular parallelepiped. Other shapes may also be useful. The weight container, in one embodiment, includes a first opening and a second opening. The first opening can be configured to connect to an actuator such as a pneumatic compressor unit to inject compressed air into the container. In one embodiment, the first opening is positioned in the upper part or the upper portion of the container. Regarding the second opening, the second opening is configured to fill the container with DF or to remove DF from the container. In one embodiment, the second opening is positioned, for example, on the side of the lower part of the container to facilitate the removal of DF. Positioning the second opening at the bottom of the container may also be useful as it is configured to float. The opening, in one embodiment, can be configured to be opened and closed.

[0057] To install the catenary system, the catenary with the filled container can be suspended from a floating structure. The openings in the container are closed, for example, when filled with DF. To remove the container when it is underwater or to empty the container, an air conduit is connected to the first opening and a DF flow conduit is connected to the second opening. Then the openings are opened. Compressed air is injected through the first opening to push the DF through the second opening, for example, to a floating structure or a ship. When the container is empty, the container rises towards the sea surface. If there is no need to leave the DF and it is environmentally safe, the DF can be released into the sea.

[0058] In one embodiment, the DF can be medium-density DF or high-density DF. As the density increases, the required container becomes smaller. As described, the use of DF enables the easy installation and removal of the catenary mooring system.

[0059] Figure 4 shows a simplified embodiment of a gravity anchor 444 for offshore applications such as floating platforms or vessels. For example, the floating structure can be an offshore wind turbine platform or an oil and gas drilling platform. The gravity anchor system may be used for other offshore applications including monohulls and semi-submersibles.

[0060] The gravity anchor is configured to be positioned on the seabed 404. In one embodiment, the gravity anchor is a container filled with DF474. The gravity anchor can be a rectangular parallelepiped-shaped container. Other shapes may also be useful. For example, the gravity container should have a shape that can be stably positioned on the seabed. The gravity anchor includes a first opening 454 and a second opening 464. The first opening can be configured to connect to an actuator. The actuator includes, in one embodiment, a pneumatic compressor unit for injecting compressed air into the container. In one embodiment, the first opening is positioned at the upper part of the gravity anchor. Regarding the second opening, the second opening can be configured to fill the gravity anchor with DF or to remove DF from the gravity anchor. In one embodiment, the second opening is positioned at the side of the lower part of the container to facilitate the removal of DF. Those openings can be configured to be opened and closed.

[0061] In one embodiment, the gravity anchor is filled with DF and installed on the seabed. The opening is configured to be closed, for example. For example, the filled gravity anchor can be positioned at the desired location and placed on the seabed. To remove the gravity anchor, the DF is removed from the gravity anchor. A ship or vessel 424 can be used to remove the DF from the gravity anchor. The vessel includes an actuator unit 434 such as a compressor unit and a DF storage container 426. The actuator unit is connected to the first opening of the gravity anchor, and a DF flow conduit 466 is connected to the second opening. The opening is configured to be opened. Compressed air is injected into the gravity anchor, pushing the DF upward into the DF storage container. When the gravity anchor is empty, it floats upward towards the sea surface. The floating gravity anchor can be easily towed by the vessel. If there is no need to leave the DF and it is environmentally safe, the DF can be discharged into the sea.

[0062] In one embodiment, the DF can be medium-density DF or high-density DF. As the density increases, the required container becomes smaller. As described, the use of DF enables the easy installation and removal of the gravity anchor.

[0063] The present disclosure can be embodied in other specific forms without departing from its spirit or essential characteristics. Therefore, the foregoing embodiments are to be considered in all respects as illustrative and not restrictive of the invention described herein. Accordingly, the scope of the invention is indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.

[0064] The present disclosure can be embodied in other specific forms without departing from its spirit or essential characteristics. Therefore, the foregoing embodiments are to be considered in all respects as illustrative and not restrictive of the invention described herein. Accordingly, the scope of the invention is indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Explanation of Signs

[0065] 200 Offshore or floating wind turbine system or wind turbine platform 211 Water mass 221 Floating platform, floating module 228 Deck 231 Column 236 Flow conduit, pipe 251 Wind turbine module 253 Nacelle 254 Rotor blade assembly 281 Actuator unit 300 Catenary mooring system, floating structure 303 Seabed 313 Upper part of water mass 333 Catenary 353 Weight 404 Seabed 424 Ship, vessel 426 DF storage container 434 Actuator unit 444 Gravity anchor 454 First opening 464 Second opening 466 DF flow conduit 474 DF

Claims

1. A semi-submersible platform, comprising at least elongated hollow columns, a floating frame for fixing a plurality of said hollow columns together to form a polygon, a dense fluid contained in said hollow columns and configured to float said hollow columns, and a plurality of said hollow columns containing said dense fluid are fixed together to form a floating unit of said semi-submersible platform, wherein the volume of said hollow columns using said dense fluid as ballast is smaller compared to the volume of hollow columns using seawater as ballast, a semi-submersible platform.

2. A deck disposed at the upper end of said hollow column, comprising a deck for supporting components of said platform, the platform according to claim 1.

3. Three columns for forming a triangle, comprising a primary column and two secondary columns, and a wind turbine module disposed on the primary column, the platform according to claim 1.

4. One of said hollow columns of said floating unit functions as a primary column, and other columns of said floating unit function as secondary columns, wherein said platform further comprises a wind turbine module disposed on said primary column, the platform according to claim 1.

5. The platform according to claim 4, wherein said primary column and said secondary column form a polygon.

6. Said secondary column forms a polygon, and said primary column is disposed at a substantially center of said secondary column, the platform according to claim 5.

7. A plurality of said hollow columns are in fluid communication to provide active ballasting between a plurality of said hollow columns to keep said platform horizontal, the platform according to claim 1.

8. The platform according to claim 7, comprising an actuator unit for controlling the flow of dense fluid between a plurality of said hollow columns for active ballasting of said platform.

9. The platform according to claim 7, wherein said dense fluid comprises a medium-density dense fluid for active ballasting of said platform.

10. The dense fluid of medium density has a density of about 1.5 to 2.5 g / cm ３ The platform according to claim 9, including.

11. The platform according to claim 1, wherein said dense fluid comprises a high-density dense fluid for passive ballasting of said platform.

12. The high-density dense fluid has a density of about 2.5 to 3 g / cm ３ The platform according to claim 11, including

13. The dense fluid includes a low-density dense fluid, and the low-density dense fluid has a density of 1.2 g / cm ３ The platform according to claim 1, including the density of.

14. A method of generating electricity, A step of installing an offshore wind turbine platform on an ice floe, wherein the offshore wind turbine platform comprises: A floating unit, At least an elongated hollow column, A floating frame for fixing a plurality of the hollow columns together to form a polygon, and A dense fluid contained in the hollow column and configured to float the hollow column Comprising, The volume of the hollow column using the dense fluid as ballast is smaller compared to the volume of the hollow column using seawater as ballast, A floating unit, A wind turbine unit disposed on the floating unit, the wind turbine unit being configured to generate electricity using wind power to rotate a rotor assembly of the wind turbine unit Comprising, a step; A step of sending the electricity generated by the wind turbine unit to an onshore substation Including, a method.

15. The step of sending the electricity generated by the wind turbine unit to the onshore substation comprises: Sending the electricity to an offshore substation, Sending the electricity from the offshore substation to the onshore substation Including, the method according to claim 14.

16. Including a step of providing a plurality of wind turbine platforms using a dense fluid to form an offshore wind farm, the method according to claim 14.

17. The modular floating unit includes active ballasting, The hollow columns are configured to be in fluid communication with each other, The method includes a step of moving the dense fluid between the hollow columns using a compressor unit to level the offshore wind turbine platform, the method according to claim 14.

18. The dense fluid has a density of about 1.5 to 2.5 g / cm ３ and is the method according to claim 17.

19. A gravity anchor container including a first opening and a second opening, the first opening and the second opening being configurable to be opened and closed, a gravity anchor container; A dense fluid filling the gravity anchor container, the first opening and the second opening being configured to be closed, a dense fluid Comprising, The gravity anchor with the gravity anchor container filled with the dense fluid located on the seabed.

20. The first opening is positioned at an upper portion of the gravity anchor container, and the first opening is configured to be connected to an actuator, The second opening is positioned at a lower portion on a side of the gravity anchor, The gravity anchor according to claim 19, wherein the first opening and the second opening are configured to be opened to inject air into the gravity anchor container so as to move the dense fluid out of the gravity anchor container through the second opening.

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