Offshore gravity energy storage system and method

Abstract

The invention discloses an offshore gravity energy storage system and method. The system comprises a large rigid floating body which floats on the water surface or suspends at a certain depth underwater or a plurality of floating bodies which are connected together through a certain frame structure. A weight is arranged on the floating body, and the weight generates electricity in the process of sinking to the seabed. And energy is stored in the process of pulling up the heavy object from the seabed. A seabed weight is jointly positioned through a plurality of active and passive sonars and a GPS (Global Positioning System), and data is stored in a digital map system. And seabed weights can be found through sonar and an optical camera according to a digital map system. The horizontal position of the system can be dynamically adjusted through the thrust of a plurality of propellers of various floating bodies. When the method that the system is suspended at a certain depth underwater to run is adopted, the vertical stability of the system can be adjusted by adjusting the upward tension of the floating body or the downward tension of the anchorage system.

Description

Technical Field

[0001] This invention relates to the field of gravity energy storage technology, specifically to a marine gravity energy storage system and method. Background Technology

[0002] Because wind and solar power are unstable, neither solar nor wind power can provide stable power generation. Coal-fired power plants struggle to quickly adjust their output. Therefore, to ensure grid stability and reduce waste, large-scale energy storage power plants are needed to store the electricity generated by wind and solar power. Pumped hydro storage and compressed air storage are mature and reliable technologies, but they only meet specific terrain or geological conditions. Furthermore, their energy conversion efficiency is not high. Ideally, the cost of solar or wind power plus the cost of energy storage should not exceed the cost of coal power. Therefore, it is necessary to develop other inexpensive and reliable large-scale energy storage technologies.

[0003] Gravity energy storage technology operates on a similar principle to pumped hydro storage, except that the medium is replaced with a heavy object, significantly reducing the site selection requirements for the energy storage system. When an electric motor lifts the heavy object to a height, the electricity is converted into the potential energy of the object; as the object descends, this potential energy is released, driving a generator to produce electricity. Gravity energy storage technology no longer relies solely on large water storage volumes; its storage medium and method are variable, resulting in a considerably long service life. Furthermore, it does not experience performance degradation during periodic operation, meeting future demands for dynamic, long-life energy storage. Moreover, gravity energy storage has been proven capable of providing sub-second full-power responses.

[0004] Gravity energy storage technology requires a certain height, which significantly limits its development. Existing technologies include some solutions utilizing the natural conditions of the deep sea for gravity energy storage. For example, Chinese patent CN103867409B discloses a gravity energy storage system utilizing ocean depth differences. This system uses a single-point mooring device to lift a heavy block from the seabed and a crane to stack the lifted block onto a floating platform, thus storing energy from the weight of the object. However, the inventors discovered the following problems with this system: Firstly, the single-point mooring device and floating platform require very robust and expensive anchors and chains for anchoring. Secondly, in rough seas, the instantaneous thrust of the waves on the large floating body can easily cause the anchor chains to break, rendering the system inoperable. Thirdly, when the water is deep and the waves are large, the horizontal stability provided by this mooring method is very small, only allowing the floating body to drift near the mooring point and preventing it from accurately positioning itself above the heavy object. Secondly, even with lighting, visibility is very limited on the seabed, especially when heavy objects stir up sediment. Therefore, searching for heavy objects underwater using only optical cameras is inefficient. Thirdly, when a robot finds a heavy object, it needs to locate the hook, bring it to the object, and attach it. Finding a small hook is far more difficult than finding the heavy object itself. Finally, after deducting the buoyancy of water, only about 60% of a concrete object's weight can be used for energy storage, but the buoyancy body must be strong enough to support its entire weight. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides a marine gravity energy storage system and method, which can efficiently locate heavy objects and hooks on the seabed, and can efficiently and accurately maintain the horizontal stability of the buoy, while taking into account how to operate under strong winds, waves and underwater internal waves.

[0006] The technical solution of the present invention is as follows: In a first aspect of the present invention, a marine gravity energy storage system is provided, characterized in that it comprises: A floating platform, which floats on the sea surface or lies submerged at a certain depth below the sea surface, is equipped with a heavy object, and is equipped with one or more propellers, which hold the floating platform in a set position or move it to a desired position. A digital mapping system is used to measure and record the underwater positions of heavy objects and hooks; Heavy lifting device, used to lift heavy objects from the seabed to the floating platform; A power generation device used to convert the gravitational potential energy of a heavy object falling to the seabed into electrical energy. An underwater robot is used to locate the hooks on the bottom of a floating platform to attach heavy objects to the hooks.

[0007] In some embodiments of the present invention, the floating platform is a large rigid floating body or a ship hull platform, which floats on the sea surface; the heavy lifting device and the power generation device are set on the floating platform, and the heavy object is suspended or fixed in the water to the bottom outside the floating platform; the bottom of the floating platform is provided with a hook for fixing the heavy object for suspension and storage, a slide rail, and a trolley that moves along the slide rail. The trolley is provided with a rope and a hook. The trolley moves on the slide rail by wheels. The slide rail connects the crane and the heavy object storage area. The heavy object is suspended by the trolley and moves from the crane to the heavy object suspension and storage area via the slide rail. The heavy object is transferred between the hook for fixing the heavy object for suspension and storage and the hook under the trolley by pulling or loosening the rope. Furthermore, each trolley is equipped with an attached underwater robot to assist in hooking and releasing the hook from the weight; Furthermore, the weights suspended below the buoys are connected together by ropes or rigid objects to prevent them from colliding with each other in rough seas.

[0008] In some embodiments of the present invention, multiple rigid floats are provided, and the multiple rigid floats are connected by a rope and pulley system, wherein the length and tension of the ropes are adjusted by the pulley system; Furthermore, rigid floats can be used in conjunction with small boats equipped with lifting cranes and generators to increase flexibility in horizontal positioning.

[0009] In some embodiments of the present invention, the floating platform is suspended on the sea surface. The floating platform includes multiple main floats for suspending heavy objects and a frame structure. The frame structure is used to connect the main floats and restrict the position of the main floats within a certain range. Each main float has a hook for suspending heavy objects at its bottom. The heavy object lifting device and the power generation device are installed on a small boat. The bottom of the small boat is equipped with a rope, hook, and underwater robot for suspending heavy objects. The underwater robot hangs the heavy object on the hook under the main float, and the heavy object is transferred from the bottom of the small boat to the bottom of the main float for gravity energy storage. The horizontal position of the frame structure is maintained by the small boat pushing the frame structure through a propeller.

[0010] Furthermore, the floating platform is suspended at a certain depth below the sea surface. The floating platform includes multiple main floats for suspending heavy objects and a frame structure. Each main float has a hook at its bottom for suspending heavy objects. The frame structure is used to connect the main floats and restrict their position within a certain range. The heavy object lifting device and the power generation device are installed on a submersible vessel that can operate both on the sea surface and underwater. The submersible vessel is equipped with an air compression and inflation / deflation device. The inflation / deflation device is connected to the main floats through a vent pipe. The inflation / deflation device inflates and deflates the main floats, thereby adjusting the air pressure, displacement, and buoyancy within the main floats. Furthermore, sensors for detecting internal waves are installed in the nearby sea area. Before the internal waves arrive, the underwater suspended floating platform is brought to the surface to avoid them. After the internal waves have passed, it is submerged again to a predetermined depth for underwater suspension.

[0011] In some embodiments of the present invention, when the submersible vessel is operating underwater, it also includes a small air tanker floating on the sea surface. The small air tanker is equipped with air compression and storage equipment, and the submersible vessel can quickly inject compressed air from the small air tanker into the main buoy to adjust the buoyancy of the main buoy. Maintaining the horizontal position of the frame structure is achieved by adjusting the floats on the frame structure or by propelling the frame structure with a propeller on a submersible vessel.

[0012] In some embodiments of the present invention, an air compressor is provided in the regulating buoy of the underwater frame structure. The air compressor adjusts the air pressure, displacement, and buoyancy of itself, the frame structure, and the main buoy, thereby adjusting and controlling the vertical stability and depth of the underwater frame. And / or, the vertical stability and depth control of the main float and frame structure are regulated by anchors and chains on the seabed. In this case, the buoyancy of the frame system should be slightly greater than its weight, with the excess buoyancy balanced by the anchor and chain system.

[0013] In some embodiments of the present invention, the heavy object lifting device is a crane or a winch, the crane or winch is equipped with a lifting cable, the end of the lifting cable is connected to a remote control hook, the remote control hook is equipped with a sonar including a precision clock, a light, a camera, a pressure gauge, a propeller and an engine, the engine drives the propeller to rotate, thereby moving the intelligent remote control hook. Furthermore, the remote-controlled hook can automatically lock or unlock heavy objects.

[0014] In some embodiments of the present invention, the digital map system includes a GPS on the sea surface, a pressure gauge, a precision clock, sonar, a lighting device, a camera, and sonar on multiple floating bodies and multiple sonar beacons on the seabed; by transmitting, receiving, and measuring sonar signals or sonar echoes transmitted from multiple sonars at certain precise times, the distances and relative positions between them are calculated; the position of each weight on the seabed can be measured before it is placed on the seabed and stored in the digital map system.

[0015] In a second aspect of the invention, a method for operating a marine gravity energy storage system is provided. When energy storage is required, a heavy object is lifted by a heavy object lifting device, and an underwater robot is used to hook and unhook the hook to suspend the heavy object at the bottom of a floating platform for gravity energy storage. When discharge is needed, a heavy object is placed at the bottom of the floating platform and lowered to the seabed. The power generation device then uses the weight and potential energy of the heavy object to generate electricity.

[0016] One or more technical solutions of the present invention have the following beneficial effects: (1) The marine gravity energy storage system provided by this invention can solve the problem of accurate and rapid positioning and search of underwater heavy objects. It uses a digital map system, including GPS on the water surface, sonar on multiple floating bodies, and pressure gauges, current meters, sonar, lighting, and cameras on the underwater hook. The sonar on the hook can receive sonar signals emitted by multiple accurately positioned sonar beacons on the seabed. Since each sonar in the system has a precise clock, the distance and relative position between them can be calculated by receiving and measuring the sonar signals or response echoes emitted by multiple sonars at certain precise times. The approximate position of each heavy object on the seabed can also be measured before it is placed on the seabed and stored in the digital map system. When the hook needs to find a heavy object, it first moves to the vicinity of the heavy object according to the relative position measured by the digital map system and the emitted and received sonar signals, and then the lighting and camera can be turned on to find the heavy object.

[0017] (2) The marine gravity energy storage system provided by this invention avoids the difficulty or expense of constructing a strong anchoring system in the deep sea. The anchoring systems in this invention are optional and do not need to withstand large tensile forces. They are mainly used to control the vertical stability of the underwater floating body. The horizontal stability of the floating body mainly relies on the propeller of the floating body to generate power for stability. The reason for this is that it is difficult or costly to construct or use a robust anchoring system in the deep sea that can withstand extremely large tensile forces. It is easier to use ship power for horizontal stability. Moreover, the floating body only needs to be horizontally stabilized to a certain extent when lifting or lowering heavy objects on the seabed. At other times, it can drift with the current, as long as it can return in time for the next operation on the seabed. This can save the energy required to maintain the horizontal stability of the floating body by pushing the propeller.

[0018] (3) The marine gravity energy storage system provided by this invention can withstand strong winds and waves without being damaged by internal ocean waves. When using large rigid floats or hulls, they are unaffected by internal waves because they float on the water surface. The strength of the floats ensures that they will not break when the wind and waves are large. In addition to using propellers to control the position of large rigid floats, ropes with adjustable length and tensile strength can also be used to prevent them from colliding with each other. When using multiple small floats, each heavy object can be suspended by one float, and the floats are connected to the frame by ropes. The ropes can be elastic. In order to reduce the interaction force between the floats and the frame structure in the wind and waves, the frame structure leaves a certain space for the floats so that the floats can make circular movements in the wind and waves. The floats and the frame structure can also be submerged to a certain depth to avoid the influence of wind and waves. At this time, it is necessary to set up an internal wave detection device in the nearby sea area. Before the internal waves arrive, the floats and the frame structure can float to the surface to avoid the internal waves. After the internal waves pass, they can be submerged again.

[0019] (4) In the marine gravity energy storage system provided by the present invention, the heavy object is suspended at the bottom of the floating body rather than on or inside the hull (on the sea surface). Since the water has buoyancy on the heavy object when it is in the water, when the heavy object is suspended at the bottom of the floating body, almost all the weight of the heavy object borne by the bottom of the floating body can be used to store energy. For large rigid floating bodies, rails can be set between the heavy object suspension and storage positions to facilitate the transfer of the heavy object between the storage location and the crane. Attached Figure Description

[0020] Figure 1 This is a side view along the slide rail direction of the marine gravity energy storage system of Example 1; Figure 2 This is a side view of the marine gravity energy storage system of Example 1, perpendicular to the direction of the slide rail; Figure 3 This is a perspective top view of the marine gravity energy storage system of Example 1; Figure 4 This is a side view of the weight used in this invention; Figure 5 This is a top view of the weight used in this invention; Figure 6 This is a top view of the multiple floating platforms in Example 1 at a certain height; Figure 7 This is a side view of the multiple floating platforms in Example 1; Figure 8 This is a side view of the marine gravity energy storage system of Example 2; Figure 9 This is a partial top view of the marine gravity energy storage system of Example 2; Figure 10 This is an overall top view of the marine gravity energy storage system of Example 2; Figure 11 This is a schematic diagram showing the connection between the semi-flexible frame and the floating body of the marine gravity energy storage system in Example 2; Figure 12 This is a schematic diagram of the heavy object transfer process of the marine gravity energy storage system in Example 2; Figure 13 This is a side view of the offshore gravity energy storage system of Example 3: Figure 14 The top view of the floating platform of the offshore gravity energy storage system in Example 3 is a flexible connection.

[0021] In the diagram: 1. Floating platform; 101. Rigid floating platform; 102. Winch and pulley block; 103. Adjustable rope; 2. Sea surface; 3. Generator; 4. Electric motor; 5. Control equipment; 6. Crane; 7. Lifting cable; 8. Remote control hook; 9. Anchor chain; 10. Anchor; 11. Seabed weight; 12. Winch; 13. Weight at the fixed suspension point; 14. Cable; 15. Weight moving under the pulley; 16. Underwater robot; 17. Weight locking device; 18. Pulley; 19. Rail; 2 0. Steel frame at the end of the heavy object; 21. Small boat; 22. Main buoy; 221. First connecting rod; 222. Connecting ring; 223. Pulley; 23. Semi-flexible frame; 231. Steel pipe; 232. Connecting rope (or elastic connecting device); 233. Flexible connection; 234. Temporary connecting rod; 235. Second connecting rod; 24. Anchor buoy; 25. Limiting connecting rod control equipment; 26. Ropes and vent pipes; 27. Adjustable buoy; 28. Small buoy; 29. ​​Small air tanker boat; 30. Submersible boat. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] The existing gravity energy storage systems mentioned in the background technology have problems such as difficulty in locating heavy objects after they are placed on the seabed, difficulty in implementing floating platforms for gravity energy storage using anchor and anchor chain systems, and difficulty in operating normally in windy and wavey weather.

[0024] This invention proposes a marine gravity energy storage system, comprising: A floating platform, which is suspended on the sea surface or submerged below the sea surface, is equipped with a weight and a propeller, which keeps the floating platform in a set position. Digital mapping systems are used to measure and record the location of heavy objects on the seabed. Heavy lifting device, used to lift heavy objects from the seabed to the floating platform; A power generation device used to convert the gravitational potential energy of a heavy object falling to the seabed into electrical energy. An underwater robot is used to locate the hook on the bottom of a floating body to attach a heavy object to the hook.

[0025] Furthermore, the heavy lifting device adopts a crane or winch, and the crane or winch is equipped with a lifting cable. The end of the lifting cable is connected to a remote control hook, and the remote control hook is equipped with a propeller and an engine. The engine drives the propeller to rotate, thereby moving the intelligent remote control hook. Furthermore, the remote-controlled hook can automatically lock or unlock heavy objects.

[0026] Furthermore, the digital mapping system includes a pressure gauge, lighting, a camera, and a sonar system containing a precise clock. The sonar system includes a sonar mounted on a floating platform, a sonar beacon on the seabed, and a sonar on a remotely controlled hook.

[0027] In this invention, the sonar exploration technology employed by the digital map system utilizes the simplest sonar ranging principle: when the speed of sound is constant, the transmission distance of a sound wave is directly proportional to time. The longer the time between receiving the signal and the transmission time, the greater the distance. The location of the seabed sonar beacons is accurately positioned underwater during installation. Each sonar in the system has a precise clock, such as a high-precision quartz clock. For example, when a hook needs to know its location, its onboard pressure gauge can indicate its depth. When a nearby seabed sonar beacon transmits a sonar signal at some known specific time, the sonar on the hook can calculate the distance to that sonar beacon by measuring the time it receives the signal. Different sonar beacons can transmit signals at different times, or the transmitted signals may have different lengths or frequencies. Therefore, the hook can calculate its distance to these sonar beacons and its own location by receiving and measuring sonar signals emitted by multiple sonars at certain precise times. (Of course, there are many methods for underwater positioning using sonar. The method described above is just one of the lower-cost underwater positioning methods.) The sonar beacon, its battery, and clock can be inspected or replaced periodically. When the distance between the hook and the sonar beacon is known or very close, the sonar on the hook can also correct the clock on the sonar beacon by sending a signal. In addition to transmitting sonar signals at set times, the sonar beacon can also have a device that receives sonar signals to determine when to transmit them. For example, the sonar on the hook can emit a signal. Upon receiving the signal, the relevant sonar beacon (or other sonar) can immediately, after a certain delay, or at certain program-set times, transmit a sound wave signal. When the sonar on the hook receives these sonar signals, it can calculate its distance to each beacon or other sonar based on the time intervals. The approximate location of each weight on the seabed can also be measured before it is placed on the seabed and stored in a digital mapping system. When the hook needs to locate a heavy object, it first measures the relative position based on a digital map system and by transmitting and receiving sonar signals. Then it moves to the vicinity of the heavy object and can turn on the lights and cameras to locate it.

[0028] In this invention, to ensure the normal operation of the system during stormy weather and in the presence of internal ocean waves, a large rigid floating body can be used as a floating platform, or multiple small floating bodies with a single weight suspended below them, constrained by a frame structure. This system of frame structure plus small floating bodies (or main floating bodies) can operate on the surface or submerge to a certain depth. Underwater, it can avoid wind and waves. However, an internal wave detection device must be installed in the nearby sea area to ensure that the system rises to the surface to avoid the internal waves before they arrive. After the internal waves have passed, the system can submerge again to resume operation.

[0029] The following are several specific implementation methods: Example 1 In this embodiment, the floating platform is a large rigid floating body or ship hull platform that floats on the sea surface; the heavy lifting device and the power generation device are installed on the floating platform; the bottom of the floating platform is equipped with a fixed hook, a slide rail, a trolley, and a movable hook below it. The movable hook is connected to the trolley by a rope, and the trolley can move on the slide rail by pulleys. The slide rail connects the fixed storage area of ​​the heavy object (fixed hook) to the heavy lifting device (crane). The heavy object is moved between the fixed hook and the heavy lifting device by the trolley and the movable hook. Furthermore, each trolley is equipped with an underwater robot.

[0030] Specifically, such as Figure 1 As shown, the system includes a floating platform 1, which is suspended on the sea surface 2. A crane 6 is installed on the floating platform 1. The bottom of the floating platform 1 is provided with a fixed suspension position for heavy objects (a storage place for heavy objects with fixed hooks) and a slide rail. The slide rail is connected to the position of the crane 6. An underwater robot 16 is attached to the slide rail. The slide rail 18 moves the heavy objects lifted by the crane 6 to the fixed storage place for heavy objects via the slide rail and hangs them on the hooks at the fixed storage place for gravity energy storage.

[0031] Furthermore, to prevent the suspension ropes from becoming tangled or the weights from colliding with each other when the buoy sways, two measures can be taken: reducing the length of the suspension ropes and securing the weights together.

[0032] When a weight is transferred between the suspension point and the pulley, the suspension rope needs to be of a certain length. After the transfer is complete, the length of the suspension rope can be shortened. There are two methods: A. Adjustment is made through a vertical shaft passing through the floating body. Above the shaft (above the water surface) is a winch 12 connected to a rope. The winch 12 can be temporarily locked to an electric motor to lift heavy objects. The electric motor can move freely via some rails and can be locked to any winch to lift heavy objects.

[0033] B. The motor for lifting the heavy object can also be installed on the trolley 18 on the bottom rail of the float (e.g.) Figure 2 (As shown). This eliminates the need for vertical shafts running through the float. In this case, a winch is fixed to the bottom of the float at the load suspension storage area. The load is suspended by ropes and hooks on the winch. The engine on the pulley can either directly raise or lower the load suspended below it, or raise or lower the load suspended below the winch by locking the winch at the adjacent load suspension storage area to adjust the distance between the load and the bottom of the float, and then lock it.

[0034] like Figure 2As shown in the medium-weight locking device 17, the heavy object can also be fixed in a more robust way at the fixed suspension point, such as supporting it from below, or connecting or binding the iron frame at the bottom of the heavy object together with ropes or steel connecting rods to prevent the heavy objects from swaying and colliding.

[0035] Specifically, the floating platform 1 adopts a rigid floating body or a ship hull platform. The bottom of the floating body has both fixed hooks for hanging heavy objects and slide rails for moving heavy objects. Trolleys are installed on the slide rails, and the trolleys are connected to the slide rails via pulleys. Cables 14 and hooks are connected to the trolleys. The trolleys move on the slide rails, moving the heavy objects along the slide rails. The floating platform is also equipped with components such as an electric motor 4, a generator 3, and control equipment 5.

[0036] One optional process for transferring a heavy object from the pulley to the fixed suspension storage location is as follows: The underwater robot 16 first grasps the hook at the end of the rope below the fixed suspension location of the heavy object 13, pulls it to the heavy object suspended below the pulley, and attaches it to the moving heavy object. Then, the winch loosens the rope, and the moving heavy object 15 under the pulley gradually descends, thus suspending the heavy object from the hook at the fixed suspension location (since its rope is not loosened, its length remains unchanged). Then, the hook under the pulley is unlocked and released. A motor attached to the pulley locks with the winch at the fixed suspension location, pulls the heavy object upward, raises it to a certain height, and then locks it. At this point, the unloaded pulley, along with its attached robot and motor, can leave to move on to the next heavy object.

[0037] like Figure 2 and Figure 3 As shown, the slide rail 19 includes a linear slide rail and an arc slide rail. One end of the two linear slide rails is connected by the arc slide rail. The arc slide rail is designed so that heavy objects can be transferred between different linear slide rails 19 without relying on a specific crane.

[0038] Specifically, the crane 6 is equipped with a lifting cable 7, the end of which is connected to a remote control hook 8. The power cord and sensor signal transmission line of the remote control hook 8 are parallel to the lifting cable 7. When a heavy object is lifted, the load-bearing cable is wound separately from the power cord and signal transmission line. The remote control hook 8 can automatically lock and unlock the heavy object, which is an existing structure.

[0039] Furthermore, digital map systems have been discussed in detail above, and will not be repeated here.

[0040] Furthermore, such as Figure 4 and Figure 5As shown, a steel frame is fixedly mounted on the heavy object. The steel frame can be located at both ends of the heavy object or only at one end. The shape of the heavy object reduces resistance during movement in water. If necessary, a fixed or foldable fairing that can be detached and installed by an underwater robot can be added to its tail to reduce the resistance at the tail of the heavy object during lifting and lowering. A hook can hook onto the steel frame 20 at the end of the heavy object and can be used to suspend the heavy object. The hook searches for the heavy object based on a digital map, and then the engine drives the propeller to rotate, moving the remote-controlled hook to the position of the heavy object 11 on the seabed. The remote-controlled hook can automatically lock the heavy object, and then the heavy object 11 on the seabed is lifted by the lifting cable 7.

[0041] In this embodiment, the weight is suspended from the bottom of the floating platform, not on or inside the hull (on the sea surface). Because the water provides buoyancy when the weight is in the water, and most inexpensive weights have a density two to three times that of water, their weight increases by approximately 30-40% when out of the water. If the weight were stored inside or on the hull, the hull would have to be able to withstand a much greater weight, which cannot be used to store energy. When the weight is suspended from the bottom (in the water) outside the floating platform, almost all the weight borne by the bottom of the floating platform can be used to store energy.

[0042] In this embodiment, the float primarily relies on a propeller at its bottom to generate power and maintain its horizontal position. A degree of horizontal stabilization is only required when lifting or lowering heavy objects from the seabed. At other times, it can drift with the current, as long as it can return promptly for the next seabed lifting or lowering operation. This conserves the energy required to stabilize the float.

[0043] In this embodiment, multiple floating platforms 1 can be configured to float on the sea surface, such as... Figure 6 and Figure 7 As shown.

[0044] The working principle of the offshore gravity energy storage system provided in this embodiment is as follows: When charging is needed, the remote-controlled hook connected to the lifting cable on the crane automatically searches for a heavy object on the seabed. When the heavy object is found, the remote-controlled hook automatically locks the heavy object, and the crane lifts the heavy object to the sea surface. Then, the heavy object on the remote-controlled hook is transferred to the hook under the trolley, and the heavy object is moved to the various fixed hook positions using the slide rail. Finally, the heavy object is transferred from under the trolley to the fixed suspension position for gravity energy storage. When discharge is needed, a trolley is used to transfer the heavy object from the suspended storage point to a remote-controlled hook connected to the lifting cable under the crane. The crane, rope and remote-controlled hook are then used to lower the heavy object into the seabed, and the power is generated by the reduction of the object's potential energy.

[0045] Figure 8 The small boats in the middle can also follow Figure 1 This is done in conjunction with large rigid floating buoys. This reduces the horizontal movement of the rigid floating buoys when operating several heavy objects on the seabed simultaneously. For example, some distant heavy objects can be lifted and lowered by small boats. However, the lifted heavy objects must still be suspended below the rigid floating buoys for storage. The small boats primarily function as a flexible, horizontally positioned crane.

[0046] Example 2 In this embodiment, the floating platform is suspended on the sea surface. The floating platform includes multiple main floats connected together by a frame structure. Each main float has a hook at its bottom for suspending a heavy object. The heavy object lifting device and the power generation device are installed on a small boat. The bottom of the small boat is equipped with a hook for suspending a heavy object and an underwater robot. The underwater robot hangs the heavy object on the hook under the main float, and the heavy object is transferred from the bottom of the small boat to the bottom of the main float for gravity energy storage.

[0047] Specifically, such as Figure 8-12 As shown, the system includes a floating platform 1 and a small boat 21. Unlike embodiment 1, the floating platform includes multiple main floats 22 connected by a semi-flexible frame 23. Each main float 22 has a hook at its bottom for suspending heavy objects. The bottom of the small boat is equipped with a lifting cable 7 and an underwater robot 16. One end of the lifting cable 7 is connected to a remote-controlled hook 8, which lifts the heavy object from the seabed to the bottom of the small boat. The underwater robot 16 assists in searching for, hooking, and releasing the hook so that the heavy object can be suspended from the bottom of the small boat to the bottom of the main float 22.

[0048] The difference between this embodiment and Embodiment 1 is that in this embodiment, a single weight is suspended below an independent main float. To maintain the alignment and position of the main floats, they are confined within a frame via connecting ropes 232. The frame is constructed of semi-flexibly connected, buoyant, sealed steel pipes 231. These pipes can also be externally connected to other buoyant bodies to provide greater buoyancy. The main floats and the frame can move relatively vertically to allow the main floats to follow the waves or to float up and down depending on whether a weight is suspended. However, the horizontal movement between the main floats and the frame is limited to a small range by the connecting ropes, ensuring that the floats do not directly impact the frame. Since the main floats move in waves in a manner close to drawing circles, ideally, the space within the frame structure should allow the main floats to circle with the waves without colliding with the frame. However, the main floats are also connected to the frame by ropes to prevent them from impacting the frame structure when the waves are too large. These connecting ropes can also be elastic. Therefore, the connecting ropes and frame structure allow the main float to move in circles under normal circumstances, only pulling the float in special circumstances to prevent it from colliding with the frame.

[0049] In this embodiment, the weight under the main buoy plays a certain stabilizing role for the buoy, reducing its swaying under the action of waves.

[0050] To limit the horizontal movement of the main float within a certain range while allowing vertical movement, the main float has first connecting rods 221 on its side. Connecting ropes 232 at the frame corners are connected to these first connecting rods 221 via connecting rings 222, which can slide up and down on the first connecting rods 221. The connecting rods 221 can also be replaced by multiple connecting rings at different heights.

[0051] Furthermore, a pulley 223 can be optionally installed at the lower part of the main float 22. The small boat 21 can pull the rope at the bottom of the main float to adjust the length of the rope, thereby adjusting the distance between the weight and the bottom of the float. After adjustment, the small boat can relock the rope.

[0052] When the heavy object is transferred from under the small boat 21 to under the main float 22, the underwater robot hooks the heavy object onto the fixed hook under the main float 22. Then, the cable under the small boat 21 is lengthened, and the main float gradually takes over the weight. The heavy object can then be lifted and secured by pulling the rope under the pulley of the float from the small boat. At this point, the small boat can unlock from the float and move to the next float to lock. Alternatively, the pulley under the float can be omitted, and the cable length under the float can remain untightened.

[0053] Conversely, when transferring a heavy object from under the float to under the small boat, a remote-controlled hook 8 is attached to the connecting cable under the small boat. This hook is equipped with an automatic weight-searching system, the same as in Embodiment 1, and will not be described again. The remote-controlled hook 8 can hook onto the heavy object, and then the small boat can extend (or not extend) the cable under the float. The cable under the small boat tightens, and the weight is gradually transferred to the small boat 21. Then, the underwater robot can detach the hook under the main float from the heavy object. At this point, the small boat can unlock from the float and move to the next float to lock.

[0054] The difference between this embodiment and Embodiment 1 is that almost all the major equipment is installed on the small boat 21, including the propeller, rudder, crane, cables and remote control hook, electric motor, generator, transformer, various control devices, communication equipment, sonar, camera, and optional equipment for inflating and deflating the buoy, as well as automatic locking and unlocking devices for the frame structure, etc. The small boat can operate fully automatically without human intervention. The operator can remotely control it via a network, and the small boat is connected to the land by high-voltage cables and communication fiber optic cables.

[0055] Furthermore, such as Figure 10 As shown, the small boat can move within or around the frame to attach or unload heavy objects onto different floats.

[0056] To prevent damage to the small boat mounted on the frame structure during high winds and waves, such as Figure 9 As shown, the small boat can be locked using temporary connecting rod 234, and the distance between the frame structures can be maintained using second connecting rod 235. When the small boat moves, it must first unlock the temporary connecting rod 234 on the frame structure and then unlock the second connecting rod 235 to prevent it from obstructing its movement. Locking and unlocking can be accomplished using hooks with anti-detachment functionality. The temporary connecting rod 234 can be replaced with a temporary connecting rope, which maintains connection to part of the frame structure during movement, but the rope length can be adjusted as the boat moves to ensure it never collides with the frame structure.

[0057] When the wind and waves are high, heavy objects can be hung under the small boat to prevent it from capsizing.

[0058] The shape of the float can be chosen in many ways, such as cylindrical, rectangular, polyhedral, spherical, spindle-shaped, etc.

[0059] The working principle of the offshore gravity energy storage system provided in this embodiment is as follows: When charging is needed, the remote-controlled hook connected to the crane cable on the small boat automatically searches for a heavy object on the seabed. When a heavy object is found, the remote-controlled hook automatically locks the object, and the crane lifts the object to the surface. Then, the underwater robot suspends the object from the remote-controlled hook to the bottom of the small boat. The small boat then moves to the vicinity of the main buoy, and the underwater robot suspends the object from the bottom of the small boat to the fixed hooks at the bottom of each main buoy for gravity energy storage. When power is needed, the underwater robot suspends the heavy object from the bottom of each main buoy to the bottom of the small boat, and uses a remote-controlled hook connected to the lifting cable on the crane to lower the heavy object into the seabed, using the weight of the heavy object to generate electricity.

[0060] Example 3 To avoid interference from wind and waves, this embodiment uses multiple main floats connected by a frame structure as an underwater frame suspended below the sea surface. Multiple adjustable floats are connected to the underwater frame. The adjustable floats are located below the sea surface and are connected to small floats through snorkels. The small floats are suspended on the sea surface. The adjustable floats adjust the internal pressure according to the weight and buoyancy of the underwater frame. Furthermore, the small boat includes a small air tanker boat and a submersible boat connected by a snorkel and a connecting rope. The small air tanker boat floats on the sea surface, and the submersible boat moves between the sea surface and an underwater frame. The small air tanker boat is used to store compressed air, and the weight lifting device and power generation device are installed on the submersible boat.

[0061] In this embodiment, as Figure 13 , 14As shown, the entire system, except for a few pieces of equipment such as the snorkel, is suspended at a depth of tens of meters underwater (e.g., a depth greater than half the wavelength of the wave) where it is unaffected by waves. There is no surface frame structure, only an underwater frame structure. The balance between the buoyancy of this frame structure and the upward and downward forces such as gravity is achieved through two methods. Either method can be chosen, or a combination of both can be used.

[0062] The first method involves adjusting the buoyancy of the frame structure to pull it upwards when the upward force (such as buoyancy) is slightly less than the downward force (such as gravity). The main body of the adjusting buoy 27 is suspended in the water at a depth close to the frame structure (and therefore unaffected by waves). It has a (rigid or flexible) ventilation pipe leading to the surface. This adjusting buoy fine-tunes its buoyancy by adjusting its internal air pressure and water level, precisely regulating the upward pull on the frame structure to ensure that the upward pull plus its own buoyancy equals its own weight plus the downward force. The buoyancy and weight of the frame structure should normally be adjusted to be approximately equal by the adjusting buoy. The main buoys can also be connected to the adjusting buoy via ventilation pipes, and their buoyancy can be adjusted by the adjusting buoy. Alternatively, the main buoys can be adjusted only once by the submersible vessel each time a load is suspended or removed. In this scenario, if the main float 22 leaks air, and its buoyancy differs from its weight, it will be held in place by the frame structure via ropes, preventing it from rising or sinking. The frame structure will then bear excess upward or downward forces. All these forces acting on the frame structure can be balanced by the "adjustable float" or anchoring system. Therefore, the frame structure will not rise or sink uncontrollably. In short, the buoyancy of the frame structure can be adjusted.

[0063] To avoid adjusting the buoyancy of the frame structure too frequently, one method is to make the buoyancy of the frame structure slightly lower than its weight. As mentioned above, this allows the "adjustable float" to pull or suspend the frame structure upwards, achieving a balance between the vertical forces. Alternatively, the buoyancy of the frame structure can be made slightly greater than its weight. In this case, the following method is needed to balance the upward and downward forces acting on the frame structure.

[0064] The second method involves using an anchoring system to pull the frame structure down when the upward forces (such as buoyancy) are slightly greater than the downward forces (such as gravity). Note that the primary task of the anchoring system is not to maintain the horizontal stability of the frame structure, but rather its vertical stability. Since the buoyancy of the frame system is close to its weight, the difference is minimal even when the weight is slightly greater. Therefore, the anchoring system requires only a small force to hold the frame system in place. Consequently, the anchoring system does not need to be very powerful; it can be very simple, even using only one or a few weights from the seabed.

[0065] The first and second methods can be used individually or in combination within a system.

[0066] There are various ways to connect the main buoy to the frame structure, including flexible connections (such as ropes), semi-flexible connections (such as steel pipes with bendable ends), or rigid connections.

[0067] Furthermore, devices, such as pressure gauges, can be installed on the buoy and frame structure to measure the depth of the underwater frame structure.

[0068] Furthermore, the floating body can also have propellers and electric motors to propel the frame structure horizontally.

[0069] When the main buoy is operating underwater, its valves should be closed after each adjustment of its internal air pressure and water level to prevent gas leakage or changes in buoyancy.

[0070] The connection between the main buoy and the frame structure can be flexible (e.g., rope), semi-flexible (e.g., steel pipe, whose connection can be twisted), or rigid (e.g., steel pipe, but whose connection cannot be twisted).

[0071] The main buoy 22 and the submersible vessel 30, as well as the small air tanker 29 and the submersible vessel 30, are connected by ropes and snorkels 26. The tension and length of the ropes connecting the small air tanker 29 and the submersible vessel can be quickly adjusted by the submersible vessel. It can be very slack, in which case the small air tanker 29 will not interfere with the submersible vessel due to wave action. When needed, the connecting ropes can also be quickly shortened, at which point the small air tanker 29 can provide some buoyancy to pull the submersible vessel upwards. The magnitude of the pulling force depends on the tightness of the ropes. However, the primary purpose of the small air tanker 29 is to compress air and temporarily store it in its tank. (The small air tanker 29 can pre-compress and store a large amount of air at a pressure slightly higher than the air pressure inside the main buoy. This allows for rapid inflation of the main buoy when the submersible vessel inflates it.) The deflating process is the opposite. When it is necessary to inflate the main buoy below, the air tanker 29 can be used to inflate the main buoy via the submersible vessel. In rough seas, the gas tanker can use a propeller to maintain its horizontal position because the cable between the gas tanker and the submersible is slack.

[0072] Submersible vessels are equipped with winches, electric motors, generators, and various control devices. Equipment for inflating and deflating the buoy, as well as transformers, can be carried on either the submersible vessel or a gas tanker vessel.

[0073] This submersible vessel, similar to a submarine, contains an adjustable-displacement air tank, allowing it to vent or draw in water as needed to adjust buoyancy. It can connect to the main buoy's snorkel to further adjust its buoyancy. It can also connect to the main buoy's ropes to provide upward pulling force. Equipped with a winch and generator, it can lift heavy objects to generate or store energy. It can transfer heavy objects between itself and the main buoy. It has a propeller for adjusting its horizontal position.

[0074] For example, during energy storage, after a submersible lifts a heavy object from the seabed, a robot secures the ropes and hooks used to suspend the object from the empty main buoy to that object. The submersible then gradually inflates the main buoy (using compressed air from a surface tanker). At this point, the object has two hooks attached. As the buoyancy of the main buoy increases, the force exerted by the submersible on the object gradually decreases. To maintain the submersible's vertical balance, another hook on the submersible gradually pulls another object from the seabed. The combined force of partially lifting both objects is equal to the force required to fully lift one object; the submersible will not rise or sink due to changes in downward force, and its vertical position remains constant during lifting and transferring objects. Once the object is fully suspended from the main buoy, the submersible should already be fully suspending or lifting another object below it. After the object is lifted, the submersible transfers it to another main buoy. When the submersible has no other heavy load to pull, during the aforementioned gravity transfer process, as the weight of the load gradually shifts to the main buoy, the submersible needs to gradually expel gas to reduce its buoyancy. When the wind and waves are calm, the submersible can also surface to operate. In this case, because the buoyancy can be automatically adjusted according to changes in displacement, the transfer process is much easier. During power generation, when the main buoy transfers the heavy load to a submersible vessel, there should typically be another heavy load already lowered to the seabed beneath the submersible vessel, but the submersible vessel still bears its full weight. A hook on the submersible vessel attaches to the heavy load suspended below the main buoy, resulting in two hooks on the load simultaneously. Then, the main buoy gradually releases gas through the submersible vessel and the gas tanker to reduce displacement (the gas release process also generates electricity), and the heavy load is gradually suspended more by the submersible vessel. At this time, the pulling force of the submersible vessel on the other heavy load gradually decreases. Once the heavy load is completely transferred to the submersible vessel, the submersible vessel simultaneously and completely lowers the other heavy load to the seabed, ceasing its pulling action.

[0075] Of course, the frame structure and the underwater depth of the submersible can be adjusted according to the size of the waves. When the waves are small, it can also operate entirely on the surface. When operating on the surface, the submersible and the small gas tanker boat can be locked together for surface operations.

[0076] While suspending all the above-mentioned buoys at a certain depth below the water surface avoids interference from wind and waves, it is crucial to prevent damage from internal ocean waves. Therefore, detectors for detecting internal ocean waves need to be installed in the nearby sea area to promptly report their status. Before an internal wave arrives, the various buoys suspended underwater need to rise to the surface to temporarily avoid it. After the internal wave subsides, they can then submerge back to their original depth. If internal waves are frequent in the area, multiple compartments storing air at different pressures can be incorporated into the main buoy. This facilitates the rapid ascent and descent of the buoys. The gas in the pressure compartments can be inflated by a small boat or submersible vessel when lifting or lowering heavy objects. The compressed gas inside should be sufficient for at least one charge-discharge cycle.

[0077] Example 4 In a typical embodiment of this invention, a method for operating a marine gravity energy storage system is provided. When charging is required, a heavy object is lifted and suspended to the bottom of a floating platform by an underwater robot for gravity energy storage. When discharging is required, the heavy object at the bottom of the floating platform is placed on the seabed to generate electricity using the weight of the object.

[0078] Specifically, the offshore gravity energy storage system described in Example 1 uses a rigid floating body or a ship platform as the floating body platform. The crane, engine, and control equipment are all mounted on the floating body platform. The crane lifts the heavy object from the seabed, and an underwater robot suspends the object at the bottom of the rigid floating body platform for gravity energy storage. In windy and wavey weather, the strength of the large rigid floating body itself prevents it from breaking or bending.

[0079] Using the marine gravity energy storage system of Example 2, a semi-flexible connected floating frame is used to hold multiple independent main floats. Each main float carries a weight. Since the main floats move in waves in a circular motion, if sufficient space is provided within the frame for the main floats to move in circles, the main floats will not exert significant impact on the frame. Therefore, the frame and the main floats can be connected flexibly (e.g., by ropes or springs). Each main float can float freely up and down, but can only move horizontally to a limited extent. The vertical force caused by the waves is thus counteracted by the up-and-down movement of the main floats. When the horizontal movement of a main float is less than its allowed free movement, it will not exert tension on the frame structure. Only when its horizontal movement demand exceeds the degree of freedom allowed by the horizontal ropes will the force act through the ropes at the flexible connection points of the semi-rigidly connected frame structure. These ropes can also be elastic. The horizontal forces acting on multiple main floats will cancel each other out. Only the resultant force in the same direction will propel the entire frame structure to float in one direction. This movement can be counteracted by the opposing forces of multiple propellers from multiple small boats.

[0080] Because the waves only extend about half a wavelength underwater, if the main buoy is suspended at a depth of half a wavelength during strong winds and waves, it can be largely protected from the effects of the waves.

[0081] In the operation of the offshore gravity energy storage system in Example 3, the system normally operates underwater to avoid interference from wind and waves. It only surfaces temporarily to avoid internal waves when they are detected. While suspended underwater, the system's vertical stability can be provided by the upward pull of the regulating buoy or the downward pull of the anchor / chain system. When using a submersible vessel, compressed air can be supplied to the submersible vessel via a tanker ship, which in turn supplies compressed gas to the main buoy to adjust its buoyancy. The regulating buoy itself also has an air compressor and propeller, and can adjust and stabilize the horizontal position of the underwater frame and the depth at which it submerges below the sea surface.

[0082] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A marine gravity energy storage system, characterized in that, include: A floating platform, which floats on the sea surface or lies submerged at a certain depth below the sea surface, is equipped with a heavy object, and is equipped with one or more propellers, which hold the floating platform in a set position or move it to a desired position. A digital mapping system is used to measure and record the underwater positions of heavy objects and hooks; Heavy lifting equipment is used to lift heavy objects from the seabed to the floating platform; A power generation device used to convert the gravitational potential energy of a heavy object falling to the seabed into electrical energy. An underwater robot is used to locate the hooks on the bottom of a floating platform to attach heavy objects to the hooks.

2. The offshore gravity energy storage system as described in claim 1, characterized in that, The floating platform is a large rigid floating body or ship hull platform that floats on the sea surface. The heavy object lifting device and power generation device are set on the floating platform. The heavy object is suspended in the water or fixed to the bottom outside the floating platform. The bottom of the floating platform is equipped with a heavy object fixing and suspension storage hook, a slide rail, and a trolley that moves along the slide rail. The trolley is equipped with ropes and hooks. The trolley moves on the slide rail by wheels. The slide rail connects the crane and the heavy object storage area. The heavy object is suspended by the trolley and moves along the slide rail from the crane to the heavy object suspension storage area. The heavy object is transferred between the hook used for heavy object fixing and suspension storage and the hook under the trolley by pulling or releasing the rope. Furthermore, each trolley is equipped with an attached underwater robot to assist in hooking and releasing the hook from the weight; Furthermore, the weights suspended below the buoys are connected together by ropes or rigid objects to prevent them from colliding with each other in rough seas.

3. The offshore gravity energy storage system as described in claim 2, characterized in that, Multiple rigid floats are set up, and the multiple rigid floats are connected by a rope and pulley system. The length and tension of the ropes are adjusted by the pulley system. Furthermore, rigid floats can be used in conjunction with small boats equipped with lifting cranes and generators to increase flexibility in horizontal positioning.

4. The offshore gravity energy storage system as described in claim 1, characterized in that, The floating platform is suspended on the sea surface and includes multiple main floats for suspending heavy objects and a frame structure. The frame structure is used to connect the main floats and restrict their positions within a certain range. Each main float has a hook at its bottom for suspending heavy objects. The heavy object lifting device and power generation device are installed on a small boat. The bottom of the small boat is equipped with ropes, hooks, and an underwater robot for suspending heavy objects. The underwater robot hooks the heavy object onto the hook under the main float, and the heavy object is transferred from the bottom of the small boat to the bottom of the main float for gravity energy storage. The horizontal position of the frame structure is maintained by the small boat pushing the frame structure through a propeller.

5. The offshore gravity energy storage system as described in claim 1, characterized in that, The floating platform is suspended at a certain depth below the sea surface. The floating platform includes multiple main floats for suspending heavy objects and a frame structure. Each main float has a hook at its bottom for suspending heavy objects. The frame structure is used to connect the main floats and restrict their position within a certain range. The heavy object lifting device and power generation device are installed on a submersible vessel that can operate both on the sea surface and underwater. The submersible vessel is equipped with an air compression and inflation / deflation device. The inflation / deflation device is connected to the main floats through a vent pipe. The inflation / deflation device inflates and deflates the main floats, thereby adjusting the air pressure, displacement, and buoyancy within the main floats. Furthermore, sensors for detecting internal waves are installed in the nearby sea area. Before the internal waves arrive, the underwater suspended floating platform is brought to the surface to avoid them. After the internal waves have passed, it is submerged again to a predetermined depth for underwater suspension.

6. The offshore gravity energy storage system as described in claim 5, characterized in that, When the submersible vessel is operating underwater, it also includes a small air tanker boat floating on the sea surface. The small air tanker boat is equipped with air compression and storage equipment. The submersible vessel can quickly inject compressed air from the small air tanker boat into the main buoy to adjust the buoyancy of the main buoy. Maintaining the horizontal position of the frame structure is achieved by adjusting the floats on the frame structure or by propelling the frame structure with a propeller on a submersible vessel.

7. The offshore gravity energy storage system as described in claim 6, characterized in that, The underwater frame structure is equipped with an air compressor in its regulating buoy. The air compressor regulates the air pressure, displacement, and buoyancy of itself, the frame structure, and the main buoy, thereby regulating and controlling the vertical stability and depth of the underwater frame. And / or, the vertical stability of the main buoy and frame structure, as well as the control of depth, are adjusted through seabed anchors and anchor chains.

8. The offshore gravity energy storage system as described in claim 1, characterized in that, The heavy lifting device uses a crane or winch. The crane or winch is equipped with a lifting cable. The end of the lifting cable is connected to a remote control hook. The remote control hook is equipped with a sonar, light, camera, pressure gauge, propeller and engine, including a precision clock. The engine drives the propeller to rotate, which in turn moves the intelligent remote control hook. Furthermore, the remote-controlled hook can automatically lock or unlock heavy objects.

9. The offshore gravity energy storage system as described in claim 1, characterized in that, The digital mapping system includes a GPS on the sea surface, a pressure gauge, a precision clock, sonar, lighting, and a camera on a remote control hook, as well as sonar on multiple floating bodies and multiple sonar beacons on the seabed; by transmitting, receiving, and measuring signals or sonar echoes emitted from multiple sonars, the distance and relative position between them can be calculated; the position of each weight on the seabed can be measured before it is placed on the seabed and stored in the digital mapping system.

10. A method for operating a marine gravity energy storage system as described in any one of claims 1-9, characterized in that, When energy storage is needed, the heavy object is lifted by a lifting device, and then an underwater robot helps to hook and unhook the object to suspend it at the bottom of the floating platform for gravity energy storage. When discharge is needed, a heavy object is placed at the bottom of the floating platform and lowered to the seabed. The power generation device then uses the weight and potential energy of the heavy object to generate electricity.

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