Dense fluid for ballasting

Abstract

Dense fluids for offshore applications such as wind turbine platforms, oil and gas platforms, gravity anchors, catenary counterweights, and other gravity-based structures are disclosed. The dense fluid may be mixed with the low density fluid and the high density solid particles to form an intermediate dense fluid. The intermediate dense fluid is mixed with medium density solid particles having the same density as the intermediate dense fluid to form a dense fluid having a desired target density. By selecting a large number of and inexpensively available medium density particles, a dense fluid can be produced economically and efficiently.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of U.S. patent application No. 17 / 068,801, filed on October 12, 2020, entitled “Pumped Hydro Energy Storage System and Method”. This application is also a continuation-in-part of U.S. patent application No. 18 / 096,127, filed on January 12, 2023, entitled “Pumped Hydro Energy Storage System and Method, including Fire Extinguishing Features”. This application also claims priority to U.S. provisional application No. 63 / 391,330, filed on July 22, 2022. All disclosures are incorporated herein by reference for all purposes. Technical Field

[0001] The present disclosure relates generally to offshore wind turbines and other floating structures and gravity-based structures. In particular, the present disclosure relates to the use of dense fluids in ballast for offshore wind turbines, other floating structures and gravity-based structures to provide a cost-effective solution. In addition, the ballast and structures can be easily recovered from the seabed or lake bottom and estuary. Background Art

[0002] Global warming has raised major concerns about the long-term viability of the Earth. The primary cause of global warming is the production of greenhouse gases including water vapor, carbon dioxide (CO2), methane, nitrous oxide, and chlorofluorocarbons (CFCs). A key culprit for the emission of CO2 into the Earth's atmosphere is the burning of fossil fuels. Fossil fuels are used for a variety of purposes, including electricity generation.

[0003] In order to slow down global warming, the green energy movement has gradually emerged. One type of green energy includes the use of wind turbines to generate electricity. As a result, many wind farms have emerged both on land and at sea. For example, as of 2022, the global offshore wind turbine power generation capacity is about 64.3 gigawatts (GW). Offshore wind turbines (e.g., in the ocean, lake, or large body of water) are more efficient because of the higher wind speeds at sea.

[0004] However, the overall power generation of offshore wind turbines is currently small because they are more expensive than onshore wind turbines. This is because the foundations of offshore wind turbines are fixed to the bottom of water, such as the seabed or lake bottom, which greatly increases the cost. In addition, the deeper the wind turbine is located, the higher the cost.

[0005] Based on the above discussion, it is necessary to provide a cost-effective way to generate electricity from offshore wind turbines. Summary of the invention

[0006] 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 supporting the hollow columns together to form a polygon, and a dense fluid contained in the hollow columns. The dense fluid is used to float the columns. The hollow columns containing the dense fluid are supported together to form a floating unit of the semi-submersible platform. Compared with hollow columns using seawater as ballast, the hollow columns using the dense fluid as ballast are smaller in size. In another embodiment, a gravity anchor or other type of gravity-based structure

[0007] Another embodiment relates to a method of generating electricity. The method includes 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 supporting the hollow columns together to form a polygon, and a dense fluid contained in the hollow columns. The dense fluid is used to float the columns. By using the dense fluid as ballast, the volume of the hollow columns can be smaller than using seawater as ballast. A wind turbine unit is disposed on the floating unit. The wind turbine unit is used to use wind power to rotate a rotor assembly of the wind turbine unit to generate electricity. The electricity generated by the wind turbine unit is transmitted to an onshore substation.

[0008] 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 open or closed. DF fills the container so that the gravity anchor is located on the seabed.

[0009] By referring to the following description and drawings, these and other advantages and features of the embodiments disclosed herein will become apparent.In addition, it should be understood that the features of the various embodiments described herein are not mutually exclusive and can exist in various combinations and arrangements. BRIEF DESCRIPTION OF THE DRAWINGS

[0001] In the drawings, like reference numerals generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention.

[0002] Figure 1A simplified process for forming a dense fluid is shown;

[0003] Figure 2 A simplified embodiment of an offshore wind turbine system is shown;

[0004] Figure 3 shows a simplified embodiment of a catenary mooring system; and

[0005] Figure 4 A simplified embodiment of a gravity anchor is shown. DETAILED DESCRIPTION

[0010] Embodiments relate to offshore wind turbines and ballast fill materials using dense fluids. For example, the density of the dense fluid is greater than the density of water or seawater. The density can vary depending on the application. For example, for ballast fill materials used in offshore wind turbines, the density can range from 1.2 g / cm 3 To 3-4g / cm 3 , or even larger. For example, for applications that replace seawater as a ballast filling material, the dense fluid can be a low-density dense fluid, such as about 1.2 g / cm 3 Using the dense fluid described herein as an alternative to seawater is advantageous because it contains no living organisms, so no biocides are required. In active ballast applications, the dense fluid may have a density of about 1.5-2.5 g / cm 3 Medium density dense fluid. With a higher density (e.g. about 2.5-3gm / cm 3 Or even higher) can be used for passive ballast applications. For example, 5-7 g / cm 3 Or even higher denser fluids may also be used for other applications.

[0011] Although the above-mentioned dense fluid is described as a ballast fill material used as ballast for offshore wind turbines, the above-mentioned dense fluid can also be used for other applications. For example, the dense fluid can be used for semi-submersible platforms, gravity anchors, dead loads to keep catenaries taut, or other types of gravity-based structures for offshore wind or offshore oil and gas applications. The dense fluid can also be used in pumped storage applications, as described in U.S. Patent Application No. 17 / 068,801, which has been incorporated herein by reference. Embodiments also relate to stable and cost-effective dense fluids.

[0012] In one embodiment, the stable dense fluid DF comprises the following expression: DF=(P1)d1+(P2)d2+(P3)d3, in, d1 = low-density fluid with density D1; d2 = medium-density particles with density D2; d3 = high-density particles with density D3; P1 = volume percentage of d1; P2 = volume percentage of d2; P3 = volume percentage of d3; and D1 <D2<D3。

[0013] DF target density D T Lower than density D3 and higher than D1. In one embodiment, D T Selected to provide increased density, yet still flow. For example, D T is the density compatible with the fluidity. For example, D of DF T It may be about 1.2-7 times the specific gravity of water. For example, depending on the application, the DF may be a low-density DF, a medium-density DF, or a high-density DF. It may also be useful to provide a DF with other densities.

[0014] In one embodiment, d1 may 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, the density of water (D1) is about 1 g / cm 3 For d3, the density of high-density solid particles is higher than D T In one embodiment, the density D3 of the high-density particles may be about 4.5-5 g / cm 3 For example, d3 may include barite, magnetite, or a combination thereof. Other types of high density particles with other D3 may also be useful. For example, the value of D3 may depend on the application. T It may be desirable to have a higher D3. For example, a higher density of high-density particles, such as lead particles, steel particles, tungsten particles, depleted uranium particles, or a combination thereof, may be used to obtain a higher D3. T .

[0015] In one embodiment, (P1)d1+(P3)d3 produces a product having a medium density D I Medium-density fluid DF I In one embodiment, medium density solid particles d2 are added to DF I , to convert D I Increase to D T For example, to DF I Add d2 to generate D T Add to DF I The volume of d2 in DF should be such that DF has D T The amount of d2 added depends on, for example, D I and DT .

[0016] In one embodiment, the medium density particles d2 include solid particles (same or different type) having a density equal to about D2. In one embodiment, d2 is selected to have D2 such that d2 is about I Neutral buoyancy in DF I D I In the stable case, d2 is chosen to have a value approximately equal to D I For example, D2 should be in D I Preferably, D2 should be within about ±1-5% of D I Therefore, choosing d2 to have neutral buoyancy will not I When d2 is added, the flow of the resulting DF is hindered.

[0017] In one embodiment, d2 may include peridotite, calcite, dolomite, or a combination thereof. For example, d2 may have a relative humidity of about 2.8 g / cm 3 For example, 2.8 g / cm 3 It can be used for density from 2.8g / cm 3 DF I Producing a DF with a density of about 3-4 times the specific gravity of water. Producing a DF with other specific gravity relative to water may also be useful. Other types of d2 may also be useful. For example, d2 may depend on D I and cost. Preferably, based on D I , d2 is selected to have a relatively lower cost compared to d3. For higher D T , d3 can be selected based on the needs of a specific application.

[0018] To improve the stability of the solid particles, the solid particles may optionally be coated with a surfactant coating. The surfactant coating may be used to hinder flocculation to stabilize the DF, thereby improving the fluidity of the DF. Other techniques for improving the stability and fluidity of the DF may also be useful. For example, mixing d3 with a slurry (e.g., a density of about 1.2 g / cm 3 Mixing with peridotite mud has been found to be effective in improving particle stability. The size of particles in peridotite mud may be about 60um or smaller.

[0019] The size of the solid particles may be about tens of microns to 1 cm or more in diameter. Other sizes of high-density particles may also be useful. For d2, the size may be about 10-100um. For example, the diameter of d2 may be about 10-100um. It should be understood that the particles may not be completely spherical. Preferably, the size of d2 is about 10-60um. For d3, in the case of Bingham plastic, its size can reach 1 cm or more. Preferably, in the case of Bingham plastic, d3 can reach 1 cm. For non-Bingham plastic applications, the size of d3 may be about 60um or less. Other sizes of d2 and d3 may also be useful.

[0020] If the particles are minerals provided by a mining company, they may have a wide range of sizes, for example from a few microns to over 1 cm. If they are too large, they may be processed to reduce the size of the particles to improve the flowability of the DF. The size reduction of the particles may be carried out in multiple stages, with the final stage reaching the desired maximum size of the particles. It should be understood that d2 and d3 are processed separately and that they do not need to have the same final maximum size. In some cases, in order to reduce costs, it is acceptable for the particles to have a wide range of sizes while maintaining flowability. For example, the DF may be configured as a Bingham plastic to ensure that larger particles do not sink.

[0021] As an example, DF may include water as d1. As mentioned above, the density of water is about 1 g / cm 3 For simplicity, water can be expressed as 1g / cm 3 The high density solid particles d3 are mixed with d1 to produce a density of D I Medium-density fluid DF I For example, mixing can include mechanical mixing similar to that used to form concrete. In one embodiment, d3 is selected to have a relative humidity of about 5 g / cm 3 For example, d3 can be barite. Alternatively, d3 can be magnetite. The density is about 5 g / cm 3 Other types of high density particles may also be useful. In addition, it may also be useful to select d3 with other densities. For example, d3 may have a density higher than 5 g / cm 3 In some embodiments, d3 may have a density of less than 5 g / cm 3 density.

[0022] In one embodiment, DF I With about 2.8g / cm 3 D I . Medium-dense fluid DF I Including density of about 1.2g / cm 3The peridotite mud has a density of about 5.2g / cm 3 In one embodiment, DF I The slurry comprises about 60% by volume of peridotite and 40% by volume of magnetite, producing a density of D I About 2.8g / cm 3 DF I The medium density solid particles d2 may include peridotite. Other types of d2, such as calcite, dolomite, or combinations of d2 may also be useful.

[0023] In other embodiments, a higher D can be achieved by using d3 with a higher density. T For example, d3 may be metal particles, such as iron filings or lead particles. In this case, a density of 6-7 times or more the specific gravity of water may be obtained. Other densities may be achieved by selecting appropriate d1, d2, and d3.

[0024] In one embodiment, the DF can be treated with compressed air or induced to flow. For example, the movement of the DF can be promoted by compressed air. Due to the cohesive force of the DF, it can flow through pneumatic circuit systems, such as pipes and tanks, at high speed. This has been achieved by using a 4-inch diameter, 4g / cm2, 1.5-1.5mm thick pneumatic tube with a density of 4g / cm2. 3 The DF was demonstrated by injecting compressed air at a pressure of several bars at the bottom of a vertical pipe of the DF. For example, a high-speed air blast pushes the material without any bubbles and carries the DF at a high speed of, for example, more than 1 m / s. For example, the DF flows in blocks and can flow using a lower pressure (for example, less than 8 bars).

[0025] Unlike D3, D2 can be selected from easily available low-cost minerals. By using a combination of D2 and D3 to produce T DF, can achieve lower production costs.

[0026] As mentioned above, a DF system including d1, d2 and d3 is provided. The DF system provides flexibility. For example, by appropriately selecting d2 and d3, using water or other types of fluids, the desired D can be achieved according to the application. T In addition, the components of the system can be selected to significantly reduce cost while achieving the desired D T In addition, DF can be processed using compressed air, making its application simple and easy, and energy-saving, making DF very cost-effective.

[0027] Figure 1 shows the method for forming a TThe process flow of DF is 100. At 110, a low density fluid is provided. For example, the low density fluid can be water. Other types of low density fluids may also be useful. For example, a low density fluid such as peridotite mud may also be used. For example, the peridotite mud is configured to have a density of 1.2 g / cm 3 density.

[0028] At 120, medium density solid particles d2 are provided. In one embodiment, d2 may have a density of about 2.8 g / cm 3 It may also be useful to provide d2 with other densities. In the case where d2 includes different types of medium density solid particles, the average density may be about 2.8 g / cm 3 . It should be understood that the variance of the density of different d2 should not vary too much, for example within a range of about ±1-5%. Preferably, the variance of the density of different d2 should be within a range of about ±1%. Medium density particles (e.g., d2) may include peridotite, calcite, dolomite, or a combination thereof. Other types of d2 particles may also be useful. Medium density solid particles d2 may be larger than, for example, mud particles of d1, such as tens of microns to 1 cm or more. The medium particles may optionally be coated with a surface active coating. It may also be useful to provide d2 without a surface active coating.

[0029] At 130, high-density solid particles d3 are provided. For example, d3 may have a density of about 5 g / cm 3 density. It may also be useful to provide D3 with other densities. High-density solid particles may include different types of D3. The variation in density should be within a range of about ±1-5%. Preferably, the variance should be within a range of about ±1%. Medium-density particles (e.g., D2) may be barite, magnetite, or a combination thereof. Other types of D3 particles may also be useful. High-density particles D3 may optionally be coated with a surface-active coating. It may also be useful to provide D2 without a surface-active coating.

[0030] In one embodiment, at 140, a medium-density fluid DF is formed. I DF I Comprising mixing d1 and d3. For example, the mixing can be mechanical mixing. Other mixing techniques may also be useful. As previously described, d1 may be water. In other embodiments, d1 may be an olivine mud. In one embodiment, d1 is a Bingham plastic, such as an olivine mud. Other types of Bingham plastic low-density fluids may also be useful. When a Bingham plastic is used, d3 does not need to be coated with a surfactant coating. The density of the medium-density fluid is D I In one embodiment, D I About 2.8g / cm 3 . Other D I Values ​​may also be useful.

[0031] At 150, mixed D I with d2 to obtain the desired D T DF. For example, d2 and D I Mechanical mixing. In one embodiment, d2 has a value approximately equal to D I The density of DF is D2. In the case of Bingham plastics, d2 does not need to be coated with a surface active coating. In addition, in the case of Bingham plastics, the solid particles do not exceed the shear stress required for flow. Therefore, they remain suspended in DF. In order to make DF flow, compressed air can be used.

[0032] Figure 2 A simplified embodiment of an offshore or floating wind turbine system or platform 200 is shown. The offshore wind turbine system is configured as a semi-submersible floating wind turbine system. For example, the system is configured to float on a body of water 211. As shown, the system includes a floating platform or module 221 configured to float on the water. The floating module is, for example, a semi-submersible module, with a lower portion located below the waterline 212 and an upper portion located above the waterline.

[0033] The floating module is also used to support a wind turbine module 251. The wind turbine module can be, for example, any conventional wind turbine module mounted on a floating module. For example, the wind turbine module includes a wind turbine tower. A nacelle 253 or turbine head is disposed on top of the turbine tower. A rotor blade assembly 254 is attached to the nacelle. The nacelle can house a gearbox assembly, an air brake unit, a mechanical brake unit, a turbine generator unit, and a power transmission unit. It may also be useful to provide the nacelle with other units or subsystems.

[0034] 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 enables the rotor blade assembly to rotate into the wind to maximize power generation. In addition, the blades 256 of the rotor blade assembly can be configured to have pitch adjustability. For example, the pitch of the blades can be adjusted to maximize power generation. In high wind conditions, 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 can be a supplement to other aerodynamic braking features.

[0035] The floating module includes a plurality of columns 231 that are supported together to form a semi-submersible platform for the wind turbine module. In one embodiment, the columns contain ballast for the semi-submersible platform. In one embodiment, as shown, the columns are hollow elongated cylindrical tanks that serve as buoyancy tanks or ballast tanks. Other elongated tanks that can hold ballast may also be useful. The elongated tanks may be cylindrical, for example. Other column shapes may also be useful.

[0036] In one embodiment, the floating module includes 3 columns. It may also be useful to provide more than 3 columns. For example, the floating module may include 3 to 5 columns. The size of the columns should be sufficient to serve as ballast tanks for the floating module to support the wind turbine modules. For example, the size of the columns may depend on the weight of the wind turbine modules and other components of the system, as well as the number of columns. For example, the heavier the weight of the module that the column is used to support, the larger the volume required. The volume may decrease or increase with the number of columns.

[0037] In one embodiment, the columns are supported together by a platform frame to form a structurally stable semi-submersible platform that can support wind turbine modules and other components of an offshore wind turbine system. For example, the platform frame can be configured as a truss frame, wherein the support rods constitute the truss frame for supporting the columns together. Other types of platform frames may also be useful. For example, the columns may be configured as triangular, rectangular, or pentagonal structures. Structures of other geometric shapes may also be useful. For example, the shape may depend on the number of columns. In one embodiment, the columns are configured as vertical structures. For example, the length of the columns is configured in a vertical plane perpendicular to the water surface plane.

[0038] These columns are filled with DF. For example, as mentioned above, DF has the expression (P1)d1+(P2)d2+(P3)d3. Using 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 column required is less than that of a column filled with water or seawater. The density of water or seawater is slightly lower or higher than 1 g / cm 3 On the other hand, DF may have a specific gravity of water or seawater, for example 2-3 times, or even greater. Therefore, the volume of the column may be reduced proportionally. For example, for a given diameter, the length of the column may be reduced proportionally. However, the column has a minimum length. Therefore, the diameter of the column may be reduced.

[0039] In some embodiments, the pillars may be filled with low-density DF, for example, with a density of 1.2 g / cm 3 DF. Although it has a lower density, it still has advantages over water or seawater applications. For example, since DF has no living organisms, no biocides are required. In addition, unlike seawater or water, DF can be moved using compressed air. Using compressed air requires less energy than pumps for seawater or aqueous solutions.

[0040] In one embodiment, the columns of the floating module are fluidly connected. Such a configuration enables the columns to form active ballast together. For example, the columns connected by fluid are used to form an active ballast subsystem of an offshore wind turbine system. As shown, a flow conduit or pipe 236 interconnects the ballast. For example, each ballast is interconnected with adjacent columns through a flow conduit. The flow conduit is located below the waterline or at least below the height of the DF. Other configurations of the flow conduit may also be useful. The size of the flow conduit should be sufficient to be able to efficiently and effectively transfer the DF between the columns. For example, the size of the flow conduit may depend on the fluid rheology of the DF.

[0041] The top of the floating module may include a deck 228. For example, the deck may provide a surface on the floating module to support some components of the offshore wind turbine. In some cases, the top of the column may be used as a deck. For example, the deck may include a plurality of sub-decks formed by the top of the column. In one embodiment, the wind turbine system may include a ballast controller and an actuator unit 281. In one embodiment, the actuator unit includes a compressor and a pressure vessel for storing compressed air. For example, the actuator unit is used to generate compressed air to move the DF within the active ballast subsystem. The ballast controller controls the compressor to selectively inject compressed air into the active ballast system to provide active balance of the system. In addition, the deck may include solar panels and a power storage unit to provide power to operate components such as the ballast controller and the actuator unit compressor and other components that require power.

[0042] In one embodiment, the actuator unit is in communication with the column through the top surface of the column. A valve may be provided to control which column to which compressed air is supplied from the top. When compressed air is supplied to a selected column, DF is transferred from that column through a flow conduit to other columns to provide active ballast to balance the system. For example, air is injected into one or more columns where DF is desired to be reduced, and air is exhausted from one or more columns where DF is desired to be increased. An active ballast controller may be used to control the actuator unit based on a sensor to provide active ballast. For active ballast applications, the top of the column may be reinforced to ensure that the column can withstand the compressed air injection.

[0043] Using compressed air, balancing can be achieved within 1 to 2 minutes. In addition, using compressed air requires less power than a water pump for water or seawater applications. For example, a 7.5KW compressor is sufficient compared to a 30KW pump required for seawater applications. Therefore, only 25% of the power is required compared to a seawater pump solution.

[0044] 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 may be referred to as a primary column, while the other columns may be referred to as secondary columns. In a preferred embodiment, the floating module comprises three columns, 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, it will contain less DF in a neutral state than the secondary columns.

[0045] In other embodiments, the primary column may be disposed at the center of the secondary column. For example, three or more secondary columns may surround the primary column. In such a configuration, the primary column need not be in fluid communication with the secondary column. However, it should be understood that the primary column and the secondary column may be in fluid communication. Other configurations of the floating module may also be useful.

[0046] As mentioned earlier, Figure 2 The system includes active ballast. In such an application, the DF filling the column can be a medium density DF. The medium density DF may have a density of about 1.5-2.5g / cm 3 Other densities of DF may also be useful for filling the columns of the active ballast system.

[0047] In other embodiments, the system includes passive ballast. In the case of passive ballast, the columns of the floating module do not need to be fluidly connected via flow tubes. This is because, in a passive ballast system, the DF remains stationary. For example, the floating module is configured with a DF that makes the system horizontal. However, it should be understood that the columns of the passive ballast system can be fluidly connected. In a passive ballast system, the DF can be a high-density DF. The high-density DF can include a higher density than that used in an active ballast system. For example, the high-density DF may be about 2.5-3 g / cm 3 High-density DF of other densities used in passive ballast systems may also be useful.

[0048] In another embodiment, the floating module is used to replace seawater. For example, the floating module is filled with low-density DF. For example, the low-density DF has a density of about 1.2 g / cm 3 In one embodiment, the low-density DF is peridotite mud. For example, it contains a low-density fluid d1, d1 is peridotite mud. Other types of low-density DF may also be useful. In some embodiments, the low-density DF can be expressed as: DF=(P1)d1+(P2)d2. In one embodiment, d1 can be water and d2 can be medium density particles. For example, the size of the medium density particles can be less than about 60 um. For example, the medium density particles can include peridotite. Other types of fine medium density particles may also be useful.

[0049] The offshore wind turbine platform may be part of an offshore wind farm having multiple wind turbine platforms. The electricity generated by the wind turbine platform is transmitted to an onshore substation for further transmission. For example, the electricity is then transmitted to a power grid so that the electricity can be distributed to end users for use. In some embodiments, the electricity from the platform may be transmitted to an offshore substation. The offshore substation then transmits the electricity to an onshore substation.

[0050] Figure 3 A simplified embodiment of a catenary mooring system 300 is shown for use in offshore applications such as floating structures, including floating platforms or ships. For example, the floating structure may include an offshore wind turbine platform or an oil and gas drilling platform. The catenary mooring system may also be used in other offshore applications, including monohulls and semi-submersible vessels.

[0051] like Figure 3 As shown, a floating structure 300 floats on top 313 of a body of water (e.g., an ocean). The floating structure is moored using catenaries 333. For example, the catenary system may include a plurality of catenaries, such as ropes or chains connected to the floating structure. For example, a first end of the catenary is connected to or extends from the floating structure. As for the second end, due to the weight of the catenary, they are configured to be located on the seabed 303.

[0052] In one embodiment, a counterweight 353 is suspended from the catenary. The counterweight is used to provide appropriate tension to ensure the correct positioning of the floating structure. For example, the counterweight is used to make the catenary form an angle of about 30-40° with the seabed. Other tension configurations of the catenary may also be useful.

[0053] In one embodiment, the counterweight suspended from the catenary includes a counterweight container filled with DF. The counterweight container can be a rectangular parallelepiped shaped container. Other shapes may also be useful. In one embodiment, the counterweight container includes a first opening and a second opening. The first opening can be configured to be connected to an actuator, such as an air compressor unit, for injecting compressed air into the container. In one embodiment, the first opening is located at the upper or top portion of the container. The second opening is configured to fill the container with DF or discharge DF from the container. In one embodiment, the second opening is located on the side, such as at the lower portion of the container, to facilitate the discharge of DF. Because the container is configured to float, it may also be useful to set the second opening at the bottom of the container. In one embodiment, the opening can be configured to be open or closed.

[0054] To install the catenary system, a catenary with a filled container can be suspended on a floating structure. For example, when filled with DF, the opening of the container is closed. To unload or empty the container in the water, an air duct is connected to the first opening and a DF flow duct is connected to the second opening. The openings are then opened. Compressed air is injected through the first opening, forcing the DF to flow through the second opening and reach, for example, a floating structure or a ship. When the container is emptied, it floats to the surface of the sea. In the case where the DF does not need to be stored and is safe for the environment, the DF can be released into the ocean.

[0055] In one embodiment, the DF can be a medium density DF or a high density DF. The higher the density, the smaller the container required. As mentioned above, the use of DF can facilitate the installation and removal of the catenary mooring system.

[0056] Figure 4 A simplified embodiment of a gravity anchor 444 is shown for use in offshore applications such as floating structures, including floating platforms or ships. For example, the floating structure may include an offshore wind turbine platform or an oil and gas drilling platform. The gravity anchor system may also be used in other offshore applications, including monohulls and semi-submersible vessels.

[0057] The gravity anchor is configured to be located on the seabed 404. In one embodiment, the gravity anchor is a container filled with DF 474. The gravity container can be a container in the shape of a cuboid. Other shapes may also be useful. For example, the gravity container should have a shape that can be stably located on the seabed. The gravity anchor includes a first opening 454 and a second opening 464. The first opening can be configured to be connected to an actuator. In one embodiment, the actuator includes an air compressor unit for injecting compressed air into the container. In one embodiment, the first opening is located at the top of the gravity anchor. The second opening can be configured to fill the gravity anchor with DF or discharge DF from the gravity anchor. In one embodiment, the second opening is located on the side of the lower portion of the container to facilitate the discharge of DF. The opening can be configured to be open or closed.

[0058] In one embodiment, the gravity anchor is filled with DF and installed on the seabed. For example, the opening is configured to be closed. For example, the filled gravity anchor can be positioned at a desired location and placed on the seabed. In order to unload the gravity anchor, DF is removed from it. In order to remove DF from the gravity anchor, a ship or vessel 424 can be used. The vessel includes an actuator unit 434 (e.g., a compressor unit) and a DF storage container 426. The actuator unit is connected to a first opening of the gravity anchor, and a DF flow conduit 466 is connected to a second opening. The opening is configured to open. Compressed air is injected into the gravity anchor, forcing DF to flow upward toward the DF storage container. When the gravity anchor is emptied, it floats to the surface of the sea. The floating gravity anchor can be easily towed by a vessel. In the case where DF does not need to be stored and is safe for the environment, DF can be released into the ocean.

[0059] In one embodiment, the DF can be a medium density DF or a high density DF. The higher the density, the smaller the container required. As mentioned above, the use of DF can facilitate the installation and removal of the gravity anchor.

[0060] The present disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. Therefore, the foregoing embodiments should be considered in all respects as illustrative rather than limiting the invention described herein. Therefore, the scope of the present invention is indicated by the appended claims rather than the foregoing description, and all changes within the meaning and equivalent range of the claims are intended to be included in the claims.

[0061] The present disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. Therefore, the foregoing embodiments should be considered in all respects as illustrative rather than limiting the invention described herein. Therefore, the scope of the present invention is indicated by the appended claims rather than the foregoing description, and all changes within the meaning and equivalent range of the claims are intended to be included in the claims.

Claims

1. A semi-submersible platform, comprising: At least the slender hollow columns, a floating frame for supporting the hollow columns together to form a polygon, and a dense fluid contained in the hollow column, the dense fluid being used to float the column, wherein: the hollow columns containing the dense fluid supported together form a floating unit of the semi-submersible platform, and Compared to hollow columns using seawater as ballast, the hollow columns using dense fluid as ballast are smaller in volume.

2. The platform according to claim 1 comprises a deck disposed on the top end of the columns, wherein: The deck supports components of the platform.

3. The platform according to claim 1, comprising: Three columns forming a triangle, the three columns comprising a main column and two secondary columns; as well as A wind turbine module is arranged on the main column.

4. The platform of claim 1, wherein: One of the columns of the floating unit serves as a primary column, and the other columns of the floating unit serves as a secondary column; and Also included is a wind turbine module disposed on the main column.

5. The platform according to claim 4, wherein: The main column and the secondary column form a polygon.

6. The platform according to claim 5, wherein: The secondary columns form a polygon; and The primary column is disposed approximately at the center of the secondary column.

7. The platform according to claim 1, wherein: The columns are in fluid communication to provide active ballast between the columns to keep the platform level.

8. The platform according to claim 7, comprising actuator units to control the flow of dense fluid between the columns for active ballasting of the platform.

9. The platform according to claim 7, wherein: The dense fluid includes a medium-density dense fluid, and the medium-density dense fluid is used for active ballast of the platform.

10. The platform according to claim 9, wherein: The medium density dense fluid includes about 1.5-2.5g / cm 3 density.

11. The platform according to claim 1, wherein: The dense fluid includes a high-density dense fluid, and the high-density dense fluid is used for passive ballast of the platform.

12. The platform according to claim 11, wherein: The high-density dense fluid includes about 2.5-3g / cm 3 density.

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

14. A method for generating electricity, comprising: An offshore wind turbine platform is installed on a body of water, wherein the wind turbine platform comprises Floating unit, including At least the slender hollow columns, a floating frame for supporting the hollow columns together to form a polygon, and a dense fluid contained in the hollow column, the dense fluid being used to float the column, and Wherein, compared with the hollow column using seawater as ballast, the hollow column using dense fluid as ballast has a smaller volume; A wind turbine unit is disposed on the floating unit, wherein the wind turbine unit is used to use wind power to rotate a rotor assembly of the wind turbine unit to generate electricity; and the electricity generated by the wind turbine unit is transmitted to an onshore substation.

15. The method according to claim 14, wherein: Transmitting the electricity generated by the wind turbine unit to the onshore substation comprises: transmitting said electricity to an offshore substation; and The electric power is transmitted from the offshore substation to the onshore substation.

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

17. The method of claim 14, wherein: The floating module unit includes active ballast; The posts are configured to be in fluid communication with each other; and A compressor unit is used to move the DF between the columns to keep the platform level.

18. The method according to claim 17, wherein: The DF comprises about 1.5-2.5 g / cm 3 density.

19. A gravity anchor, comprising: a gravity anchor container, the gravity anchor container comprising a first opening and a second opening, the first opening and the second opening being configurable to be open or closed; a dense fluid filling the gravity anchor container, wherein the first opening and the second opening are configured to be closed; and Wherein, the dense fluid filled gravity anchor container is located on the seabed.

20. The gravity anchor of claim 19, wherein: The first opening is located at the top of the gravity anchor container, and the first opening is configured to be connected to an actuator; The second opening is located at a lower portion of one side of the gravity anchor; as well as The first opening and the second opening are configured to open to inject air into the gravity container to discharge the dense fluid out of the gravity anchor container through the second opening.

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