Seabed energy storage device and method

Abstract

The invention discloses a seabed energy storage device and method, and belongs to the technical field of energy storage, the seabed energy storage device comprises a water storage tank and an air conduit, the air conduit is connected with an air compressor and an air turbine generator, the bottom of the water storage tank is connected with a water pipe and a hydro-generator, and the water storage tank is communicated with external seawater through the hydro-generator arranged at the bottom. The water storage tank is filled with seawater through the water pipe by means of the seawater pressure of the seabed, when electricity storage is needed, the air compressor is started, the seawater in the water storage tank is discharged through the water pipe by means of high-pressure air, when electricity generation is needed, the high-pressure air generates electricity through the air turbine generator, and electricity generation is achieved. Meanwhile, due to the fact that the air pressure in the water storage tank is reduced and the pressure difference between the air pressure and seawater outside the water storage tank, the outside seawater flows through the hydro-generator through a water pipe on the lower portion, and power generation is achieved. The storage problem of ocean wind power and photoelectricity can be solved, and then the stable supply-demand relation of energy is balanced.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage, and in particular to a submarine energy storage device and method. Background Art

[0002] The amount of electricity generated by offshore wind power depends on the wind speed, which is very unstable, which means that in weak or no wind conditions, the amount of electricity generated will drop sharply and cannot be stably supplied to the grid. The time when wind energy is generated may not match the time when the grid needs it. With the large-scale construction of wind and solar energy in my country's oceans, the widespread application of intermittent renewable energy such as wind and solar power generation in the oceans has increased the demand for electricity storage. The use of energy storage equipment to stably store the generated renewable energy has become a hot topic that has attracted much attention.

[0003] With regard to the above-mentioned related technologies, the applicant has found that during offshore wind power and photovoltaic power generation, the storage of excess wind power and photovoltaic power, as well as its use during peak power demand periods, has become a current technical challenge, especially for islands or remote areas that lack land-based energy storage facilities. Excess electricity lacks storage conditions, which makes it difficult to balance the stable supply and demand of energy. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a submarine energy storage device and method to effectively solve the storage problems of marine wind power and photovoltaic power, thereby balancing the stable supply and demand relationship of energy.

[0005] The technical solution of the present invention to solve the above technical problems is as follows:

[0006] A submarine energy storage device includes a water tank, which is placed on the seabed. The top of the water tank is connected to an air duct, which connects the outside air with the internal cavity of the water tank. The air duct is connected to an air compressor and an air turbine generator, which is connected to a power grid, which is connected to the air turbine generator. The bottom of the water tank is connected to a water pipe, which connects seawater with the internal cavity of the water tank.

[0007] Furthermore, the water pipe is connected to a hydro-generator, and the hydro-generator is connected to a power grid.

[0008] Furthermore, a float is provided at the end of the air duct away from the water storage tank.

[0009] Furthermore, a fixed frame is provided on the top of the water storage tank, and the air compressor and the air turbine generator are both placed in the fixed frame.

[0010] Furthermore, a plurality of supporting walls are provided on the side of the water storage tank, and the hydro-generator is placed between two supporting walls.

[0011] Furthermore, the water storage tanks are provided in plurality, and the plurality of water storage tanks are connected in parallel in sequence.

[0012] A method for storing energy under the sea, as shown in the following steps:

[0013] Step 1: The water tank uses the seawater pressure on the seabed to fill the water tank with seawater through the water pipe, and the air inside the water tank is discharged through the air duct. At this time, the water tank is full of seawater;

[0014] Step 2: When electricity storage is needed, electricity is transmitted to the air compressor through the power grid. The air compressor starts and presses the outside air into the water storage tank through the air duct. The seawater in the water storage tank is discharged through the water pipe using high-pressure air. At this time, the water storage tank is full of high-pressure air.

[0015] Step 3: When power generation is needed, the high-pressure air in the water tank is discharged through the air duct, and the high-pressure air generates power through the air turbine generator, and the generated electricity is transmitted to the power grid to achieve power generation.

[0016] Furthermore, in step four, seawater flows into the water storage tank through the water pipe, and the seawater generates electricity through the hydro-generator, and the generated electricity is transmitted to the power grid to realize power generation.

[0017] In summary, compared with the prior art, the above technical solution has the following beneficial effects:

[0018] (1) The present invention can solve the storage problem of marine wind power and photovoltaic power, thereby balancing the stable supply and demand relationship of energy;

[0019] (2) The present invention adopts a design of using an air turbine generator and a water turbine generator at the same time, so that the energy conversion is improved to the greatest extent, and the efficiency of comprehensive energy conversion can reach a maximum of about 70% to 80%;

[0020] (3) The present invention has the advantage of high energy conversion efficiency. The pressure environment on the seabed is conducive to storing large-scale energy, especially suitable for compressed air energy storage. The pressure of seawater can reduce the material cost and complexity of the energy storage system.

[0021] (4) The present invention has the advantage of reducing space occupation. The submarine energy storage system will not occupy land space and is suitable for use in coastal cities or island countries. It can also be combined with renewable energy systems such as offshore wind power to achieve local energy storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the overall structure of a submarine energy storage device according to an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the internal structure of a water storage tank in a submarine energy storage device according to an embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of the structure of an air turbine generator and an air compressor in a submarine energy storage device according to an embodiment of the present invention;

[0025] Figure 4 It is a schematic diagram of the top view of the structure of a hydro-generator in a seabed energy storage device according to an embodiment of the present invention;

[0026] Figure 5 It is a schematic diagram of the side view structure of a hydro-generator in a seabed energy storage device according to an embodiment of the present invention;

[0027] Figure 6 It is a front view structural schematic diagram of a hydro-generator in a seabed energy storage device according to an embodiment of the present invention.

[0028] Explanation of the accompanying drawings: 1. Water storage tank; 2. Air duct; 3. Air turbine generator; 4. Air compressor; 5. Water pipe; 6. Hydroelectric generator; 7. Float; 8. Fixed frame; 9. Support wall; 10. Power grid. DETAILED DESCRIPTION

[0029] The principles and features of the present invention are described below in conjunction with all the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0030] An embodiment of the present invention discloses a submarine energy storage device.

[0031] Reference Figure 1 and Figure 3 A submarine energy storage device includes a water tank 1, which is placed on the seabed. The top of the water tank 1 is connected to an air duct 2, which connects the outside air with the internal cavity of the water tank 1. The air duct 2 is connected to an air compressor 4 and an air turbine generator 3, which is connected to a power grid 10, which is connected to the air turbine generator 3. The bottom of the water tank 1 is connected to a water pipe 5, which connects seawater with the internal cavity of the water tank 1. Energy is captured in the water tank 1 on the seabed by using the pressure of the seabed. When high-pressure air passes through the air turbine generator 3, electricity is generated for output just like ordinary wind power and hydropower stations.

[0032] Reference Figure 1 and Figure 2 The water pipe 5 is connected to a hydro-generator 6, which is connected to a power grid 10. When water flows in and out of the water storage tank 1 on the seabed, the water flows through the hydro-generator 6, which is equivalent to "recharging". When connected to the power grid 10, it can be used as a "battery".

[0033] Reference Figure 1 and Figure 2The water storage tank 1 is usually made of concrete. The design water storage capacity of a single concrete water storage tank 1 is about 20,000 cubic meters. Assuming the seabed is 200 meters deep, a single concrete water storage tank 1 can store about 11 megawatt-hours of energy. The concrete water storage tank 1 is sunk to the seabed to store seawater and compressed air and maintain the pressure difference between the inside and outside of the water storage tank 1.

[0034] Reference Figure 1 and Figure 2 The water storage tanks 1 are arranged in a plurality, and the plurality of water storage tanks 1 are connected in parallel in sequence. Multiple concrete water storage tanks 1 can be built and connected in parallel as needed to increase the total energy storage capacity of the energy storage system.

[0035] Reference Figure 1 and Figure 2 The water tank 1 is made of prestressed concrete or prestressed ultra-high-strength concrete. The bottom plate is cast in the dock and towed to a predetermined position. The water tank 1 is then cast and sunk at the same time. After the water tank 1 is capped, it sinks to the seabed.

[0036] Reference Figure 1 , a buoy 7 is provided at the end of the air conduit 2 away from the water storage tank 1. The air conduit 2 is composed of a plurality of umbilical tubes for marine engineering, the upper end of the air conduit 2 is fixed by the buoy 7, so that the air conduit 2 floats on the sea surface, and the lower end is connected to the water storage tank 1 through a flange and a steel fixing bracket, and then the air conduit 2 on one side is connected to the air compressor 4, and the air conduit 2 on the other side is connected to the air turbine generator 3. The air compressor 4, the air turbine generator 3 and the concrete water storage tank 1 are all sealed.

[0037] Reference Figure 1 and Figure 4 The turbine generator 6 is fixed on the prefabricated base of the concrete water storage tank 1 and sunk to a predetermined position. The turbine generator 6 is sealed and connected to the concrete water storage tank 1 with a stainless steel pipe and is buried with gravel for protection. The water inlet of the turbine generator 6 is open to the seawater.

[0038] Reference Figure 1 and Figure 4 When electricity needs to be stored, the air compressor 4 presses the outside air into the concrete water tank 1 through the air conduit 2, and the seawater in the water tank 1 is squeezed and discharged into the sea through the water pipe 5, and the water tank 1 is filled with high-pressure air. When electricity needs to be generated, the air compressor 4 is started to discharge the high-pressure air in the water tank 1 through the air conduit 2, and the seawater enters the water tank 1 through the water pipe 5 and the hydro-generator 6, thereby generating electricity.

[0039] Reference Figure 1Since the seabed energy storage device adopts the design of using both the air turbine generator 3 and the water turbine generator 6 at the same time, and utilizes the height difference of seawater to store energy, the energy conversion is improved to the greatest extent, and the comprehensive energy conversion efficiency can reach about 70% to 80% at most.

[0040] Reference Figure 1 and Figure 3 A fixed frame 8 is provided on the top of the water storage tank 1, and the air compressor 4 and the air turbine generator 3 are both placed in the fixed frame 8. The fixed frame 8 made of stainless steel is used to fix the air compressor 4 and the air turbine generator 3, and the fixed frame 8 is fixedly connected to the concrete water storage tank 1 through embedded parts. Through the design of the fixed frame 8, the air compressor 4 and the air turbine generator 3 are wrapped inside the fixed frame 8, which plays a role in better protecting and fixing the air compressor 4 and the air turbine generator 3.

[0041] Reference Figure 5 and Figure 6 A plurality of supporting walls 9 are provided on the side of the water storage tank 1, and the hydro-generator 6 is placed between two supporting walls 9. The design of the supporting wall 9 greatly improves the stability of the water storage tank 1 on the seabed, and at the same time, the hydro-generator 6 is better fixed and protected.

[0042] refer to Figure 1 , a method for storing energy under the sea, as shown in the following steps:

[0043] Step 1: The water tank 1 uses the seawater pressure on the seabed to fill the water tank 1 with seawater through the water pipe 5, and the air inside the water tank 1 is discharged through the air duct 2. At this time, the water tank 1 is full of seawater.

[0044] Step 2: When electricity storage is needed, electricity is transmitted to the air compressor 4 through the power grid 10, the air compressor 4 starts, and the outside air is pressed into the water storage tank 1 through the air duct 2, and the seawater in the water storage tank 1 is discharged through the water pipe 5 by high-pressure air. At this time, the water storage tank 1 is full of high-pressure air.

[0045] Step 3: When power generation is required, the high-pressure air in the water tank 1 is discharged through the air duct 2, and the high-pressure air is passed through the air turbine generator 3 to generate power, and the generated power is transmitted to the power grid 10 to achieve power generation.

[0046] Step 4: Seawater flows into the water storage tank 1 through the water pipe 5, and the seawater generates electricity through the hydro-generator 6, and the generated electricity is transmitted to the power grid 10 to realize power generation.

[0047] With the widespread application of intermittent renewable energy such as marine wind energy and solar energy, how to balance energy supply and demand has become a key issue. Energy storage technology has therefore attracted much attention and is also a problem that urgently needs to be solved. The present invention, as a submarine energy storage method, has the following advantages:

[0048] 1. High energy density: The pressure environment on the seabed is conducive to storing large-scale energy, especially for compressed air energy storage. The pressure of seawater can reduce the material cost and complexity of the energy storage system.

[0049] 2. Reduce space occupation: Subsea energy storage will not occupy land space and is suitable for use in coastal cities or island countries. It can also be combined with renewable energy systems such as offshore wind power to achieve local energy storage.

[0050] The present invention has broad application prospects. Submarine energy storage is particularly suitable for use in combination with offshore wind farms to store excess wind power for use during peak periods of power demand. For islands or remote areas that lack land-based energy storage facilities, subsea energy storage technology can help solve power stability problems and reduce dependence on fossil fuel power generation. As the energy structure transforms toward a low-carbon and clean direction, subsea energy storage technology is expected to become part of the future smart grid 10, helping to balance energy supply and demand and improve the utilization rate of renewable energy. It can also effectively solve the storage problem of marine wind power, balance energy supply and demand, and actively contribute to the construction of the State Grid 10.

[0051] The implementation principle of a submarine energy storage device and method of the present invention is:

[0052] When the water tank 1 is sunk and placed on the seabed, it is full of water. When the offshore wind farm or photovoltaic farm has excess electricity and needs to store electricity, the outside atmosphere is compressed and injected into the water tank 1 through the air compressor 4. The seawater in the water tank 1 is squeezed and discharged into the sea through the turbine generator 6. In this way, the atmosphere in the water tank 1 and the outside seawater reach a pressure balance.

[0053] When power generation is required, the air turbine generator 3 is started, and high-pressure air flows through the air turbine generator 3 through the air duct 2 to generate power. At the same time, as the air pressure in the water tank 1 decreases, seawater outside the water tank 1 will enter the water tank 1 through the water pipe 5 and the hydro-turbine generator 6, and power generation is performed synchronously.

[0054] When electricity needs to be stored again, the air compressor 4 is started again to continue to inject compressed air into the water storage tank 1, and the above process is repeated, thereby completing the cycle of electricity storage and power generation like a battery.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A submarine energy storage device, characterized in that: The invention comprises a water storage tank (1), wherein the water storage tank (1) is placed on the seabed, the top of the water storage tank (1) is connected to an air conduit (2), the air conduit (2) connects the outside air with the internal cavity of the water storage tank (1), the air conduit (2) is connected to an air compressor (4) and an air turbine generator (3), the air turbine generator (3) is connected to an electric grid (10), the electric grid (10) is connected to the air turbine generator (3), and the bottom of the water storage tank (1) is connected to a water pipe (5), the water pipe (5) connects the seawater with the internal cavity of the water storage tank (1).

2. A subsea energy storage device and method according to claim 1, characterized in that: The water pipe (5) is connected to a hydro-generator (6), and the hydro-generator (6) is connected to a power grid (10).

3. A subsea energy storage device and method according to claim 1, characterized in that: A buoy (7) is provided at the end of the air duct (2) away from the water storage tank (1).

4. A subsea energy storage device and method according to claim 1, characterized in that: A fixed frame (8) is provided on the top of the water storage tank (1), and the air compressor (4) and the air turbine generator (3) are both placed in the fixed frame (8).

5. A subsea energy storage device and method according to claim 1, characterized in that: The side of the water storage tank (1) is provided with a plurality of supporting walls (9), and the hydro-generator (6) is placed between two supporting walls (9).

6. A subsea energy storage device and method according to claim 1, characterized in that: The water storage tanks (1) are arranged in a plurality, and the plurality of water storage tanks (1) are sequentially connected in parallel.

7. A method for storing energy on the seabed according to any one of claims 1 to 6, characterized in that: As shown in the following steps: Step 1: The water storage tank (1) uses the seawater pressure on the seabed to fill the water storage tank (1) with seawater through the water pipe (5), and the air inside the water storage tank (1) is discharged through the air conduit (2). At this time, the water storage tank (1) is full of seawater; Step 2: When electricity storage is required, electricity is transmitted to the air compressor (4) through the power grid (10), the air compressor (4) is started, and the outside air is pressed into the water storage tank (1) through the air conduit (2), and the seawater in the water storage tank (1) is discharged through the water pipe (5) by high-pressure air. At this time, the water storage tank (1) is filled with high-pressure air; Step 3: When power generation is required, the high-pressure air in the water storage tank (1) is discharged through the air duct (2), and the high-pressure air is passed through the air turbine generator (3) to generate power, and the generated power is transmitted to the power grid (10) to achieve power generation.

8. A method for storing energy on the seabed according to claim 7, characterized in that: As shown in the following steps: Step 4: Seawater flows into the water storage tank (1) through the water pipe (5), and the seawater generates electricity through the hydro-generator (6), and the generated electricity is transmitted to the power grid (10) to realize power generation.

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