Combined gravity-hydraulic electrical energy storage system

Abstract

The system according to the invention comprises a load piston (30) with the function of accumulating gravitational potential energy by lifting it vertically inside a cylinder (10) with reinforced concrete walls filled with water, said piston (30) being provided in the center with a high pressure conduit (20) that uses an impulse turbine to deliver pressurized water from the base of the cylinder to an electricity production system (50), the water processed in the cycle of electricity production (50) being discharged back into the cylinder (10) above the piston. For the energy absorption and storage cycle from the electricity network, the system also comprises an electrical energy absorption system (60) that takes in the water above the piston (30) and connects it into the high pressure conduit (20) below the piston (30).

Description

Background Technology

[0001] The combined gravity-hydraulic energy storage system is primarily used for grid operation to store large / significant amounts of energy during periods of excess grid production, enabling energy supply during peak consumption periods. The system provides energy storage with zero environmental cost and risk during operation and is constructed from 100% recyclable materials at the end of its product life. Initial environmental costs (e.g., CO2 footprint) are very low, and no materials with high environmental risks are used. The system can act as a buffer for any green energy production system, storing and supplying energy for 100% consumer-distributed grid operation.

[0002] The paper "Energy storage systems, a solution for optimizing the operation of electricity networks to which intermittent renewable sources of various energy storage systems are connected" (AGIR Briefing, Supplement 1 / 2015) mentions several technologies for storing electricity, including the so-called "pump-type hydraulic system (PHS)." This consists of a "hydraulic pumping station" that stores energy by pumping wastewater (located at the turbine outlet in the lower tank, where the wastewater is collected during hydroelectric plant operation) from an upstream pool (upper tank) in which the system produces excess electricity during periods or intervals. Such hydraulic pumping plants require lower wastewater collection pools and use reversible turbine generator assemblies (typically reversible turbines derived from Francis or Kaplan) for maximum efficiency, but the drawback is the very large water volume. The environmental cost of this technology is extremely high due to its severe impact on the landscape and rivers.

[0003] A gravity power module (GPM) is proposed on the website http: / / www.gravitypower.net / technology-gravity-power-energy-storage / . It comprises: a very large piston placed in a deep well or mine shaft filled with water, the piston equipped with sliding washers to prevent leakage around it; and a vertical return pipe located outside the piston, connecting the bottom of the piston to a reversible Francis turbine type motor coupled to an electric motor located at ground level. The piston is made of reinforced rock or concrete. The well is filled with water once at the start of operation and then shut off; no additional water is needed after this initial filling. During electricity production, as the piston descends, it forces water from the storage well up through the return pipe and through the turbine, rotating the electric motor in generator mode. When energy storage is needed, the electric motor, controlled in motor mode and powered by the mains, rotates the same turbine (reversibly) in pump mode to force water down the return pipe at the well base, thereby lifting the piston. The GPM module is only proposed at the conceptual level, and the disadvantages of using reversible technology (reversible turbine / generator set) are that it is limited by pressure (20 bar to 30 bar), low efficiency, and requires a large amount of water per MWh of storage.

[0004] Patent document CN 204061053(U), published on December 31, 2014, entitled "Hydropower system for storage of wind energy," describes a system comprising a main vertical shaft, a deeper second vertical shaft (both located in the sea), a hydropower unit (turbine generator set) located in the lower portion of the first vertical shaft, and a set of pumps located in the lower portion of the second vertical shaft. Seawater is injected into the first vertical shaft of the hydropower generator unit, supplying excess electricity through underground pipelines. The water is then transported through pipelines to the base of the second vertical shaft via the pumps driven by an external wind turbine, from where it is pumped in a pool to the surface. Thus, the pool water stores wind energy in the form of potential energy and can then be used to generate electricity.

[0005] Also known is an invention published on August 30, 2012, entitled "Electric power storing device for storage tank power plant, recovers potential energy generated by emptying tank into surrounding waters using pump devices under application of electric energy, during filling of tank" (Werner RAU), DE10 2011012261 (A1). The device has a water-filled tank on some ballast material (e.g., gravel, concrete), arranged on the seabed. The tank is connected to external air via pipes or hoses to allow for uncompressed air exchange and to form an air chamber above the water surface by emptying the tank. Water is fed into the tank from the outside via an inlet valve (coupled to a reverse turbine of an electric motor / generator) or pumped back into the surrounding waters from the inside. When electrical energy is applied, the potential energy generated by emptying the tank into the surrounding waters using a hydraulic or pneumatic pump device is recovered during the filling of the tank. The water flow rate is adjusted to adapt the power output of the reverse turbine and electric motor / generator to the grid requirements. An invention utilizes inefficient reversible technology (reversible turbine / generator set).

[0006] Furthermore, the invention US 2012 / 0049673 (Myung Hoe), published on March 1, 2012, entitled "Generator system for water tank," is also known. The invention provides a generator system comprising: a tank in the shape of a cylinder having a top opening and a bottom opening; a partition wall vertically disposed within the tank, dividing the tank into a first vertical column and a second vertical column connected near the bottom opening of the tank. Each of the cylinder plates is disposed and configured to perform piston movement via the corresponding vertical column of the tank, the cylinder plates being connected by pulleys via ropes, and each having a plurality of one-way holes for allowing only downward flow of water. An electric motor powered by a solar panel drives the pulleys to alternately lift the first cylinder plate or the second cylinder plate; a turbine generator is disposed at the bottom opening of the tank and is used to generate electricity using the water flow generated by the falling cylinder plate; a return pipe, with its lower end disposed at the bottom opening of the tank and its higher end opening to the top opening of the tank, is configured to allow water to return from the turbine generator to the tank. The efficiency of the turbine is reduced due to the water column in the return pipe. Summary of the Invention

[0007] The technical problem solved by this invention is to reduce the amount of water required to store each MWh in a gravity-hydraulic electro-energy storage system, thus achieving a high energy density per unit volume of structure.

[0008] The combined gravity-hydraulic-electric energy storage system according to the present invention includes: a large heavy-duty piston, the load of which is a high-volume-density material block symmetrically fixed on the surface of the piston to achieve a uniform mass distribution, which accumulates gravitational potential energy by vertically lifting it in a cylinder having reinforced concrete walls and a high-quality steel lining, the cylinder being filled with water, the piston being guided on the vertical wall of the cylinder by some guides and having a circular opening at the center, a high-pressure channel existing on the axis of the cylinder, the channel passing through the piston and using an impulse turbine to deliver pressurized water from the base of the cylinder to the power generation system, the discharge channel being sealed and degassed at the top, the water used in the power generation cycle being discharged back to the piston in the cylinder at atmospheric pressure through a return channel, and for the cycle of energy absorption and storage from the power grid, it also includes a high-pressure pump and a variable flow system, the system obtaining water above the piston through the return channel and introducing it into the pressure channel below the piston, causing the piston to rise, thereby accumulating energy.

[0009] Compared with the prior art, the gravity-hydraulic combined circulating electrical storage system according to the present invention has the following advantages:

[0010] - It features zero environmental costs and zero environmental risks during operation. The system is closed, therefore no matter is exchanged with the environment, and in the event of a leak, the internal fluid (water) is environmentally neutral. In the event of turbine or pump failure, crude oil will not be released into free-flowing water as in standard PHS systems. The competitive advantage of this construction is its extremely low average cost per MWh of storage and its extremely low carbon footprint of materials and equipment used. At the end of the plant's life cycle, all internal materials are 100% recyclable.

[0011] - The amount of water stored per MWh needs to be reduced, and the water is 100% reused in a completely closed loop.

[0012] - The system has different input and output devices, so its size can be unbalanced to allow full load during off-peak hours (2 to 6 hours or when there is excess green energy available) and unload during peak hours (6 to 18 hours, when there is little or no green energy available);

[0013] - Grid operation is 100% distributed in any operational sense (electricity input or output) - suitable for 100% expected use of uncontrollable green energy (i.e., wind, solar, wave, etc.).

[0014] - Allows for continuous variations in electricity production between 0% and 100% of installed output capacity, enabling full distribution to consumers in small / medium distribution networks.

[0015] - Allows for continuous absorption of electricity between 0% and 100% of the installed input capacity, enabling the full distribution of small / medium uncontrollable power generation capacity.

[0016] - An unlimited theoretical number of load-unload cycles are allowed only within the mechanical / electrical maintenance costs of the equipment.

[0017] - Allows for long-term energy storage without loss during storage, theoretically indefinite.

[0018] - Due to their small footprint and lack of special geophysical requirements, these units can be installed near power grid substations.

[0019] - This allows for the installation of such units in crowded (urban) areas because the area occupied is very small, and the completely underground construction allows the surface land to be reused for other purposes, plus zero landmark impact. Attached Figure Description

[0020] The following are combined to represent the following items. Figures 1 to 6 An embodiment of the present invention is given below:

[0021] - Figure 1A schematic diagram of the combined gravity-hydraulic-electric storage system according to the present invention;

[0022] - Figure 2 Design details of the cylinder wall / cylindrical pool;

[0023] - Figure 3 Details of the pressure channel design;

[0024] - Figure 4 Details of the heavy-duty piston design;

[0025] - Figure 5a A schematic diagram of the design of the concrete wall of the cylinder;

[0026] - Figure 5b The design of the precast concrete section of the cylinder block;

[0027] - Figure 6 The design of the cylinder block retaining ring. Detailed Implementation

[0028] The combined gravity-hydraulic electric energy storage system according to the invention operates in an energy absorption and storage cycle during periods or time intervals when the connected electrical network produces excess electricity, or when the operator of the unit decides to store energy, and in the network's electricity production cycle during peak consumption periods, or when the operator of the unit decides to extract energy. The system can also be used for long-term or short-term storage of uncontrollable renewable energy (wind and / or solar power) for use during peak consumption periods. The system can also be configured to provide 100% consumer-distributed power to small to medium-sized power grids, regardless of power generation fluctuations (using appropriate size / sufficient capacity).

[0029] refer to Figure 1The gravity-hydraulic combined circulating energy storage system consists of an upright cylinder 10 with reinforced concrete walls and a high-pressure resistant high-quality steel lining. A high-pressure channel / pipeline 20 is located on the axis. A large, heavy-duty piston 30 moves within the cylinder, accumulating gravitational potential energy by vertically lifting it within the cylinder 10. The cylinder is filled with water below and above the piston. A circular opening is provided in the center of the piston 30 to allow the high-pressure channel 20 to pass through it. The high-pressure channel 20 has at least one bend at its upper end. In the energy absorption and storage cycle, water above the piston 30 is pumped under pressure by the power input system 60 through the high-pressure channel 20 to the area below the piston, causing the piston to rise and accumulate gravitational potential energy. In the energy production cycle, pressurized water from the base of the cylinder 10 is guided to the power generation system 50 through the high-pressure channel 20, while the piston 30 is lowered using its gravitational potential energy. The pressure in the high-pressure channel remains constant regardless of the position of the piston 30, thus allowing for easy design of the input energy system 60 and the output energy system 70. Water processed in the power generation cycle is discharged at atmospheric pressure back to piston 30 in cylinder 10 via return channel 25, which is positioned above the water level of cylinder 10 and constructed below the freezing depth specific to the geographical area where the construction pool is located. Therefore, the water in cylinder 10 is used in a closed loop, compensated only by evaporation losses during system operation, and protected from frost.

[0030] The cylinder 10 is a large-sized, upright cylindrical pool, with a diameter and height of tens of meters depending on the required storage capacity. It is constructed below ground level using the method described below. The cylinder 10 has walls made of precast concrete, taking the form of a precast, prestressed cylindrical shell / hollow segment 12 (an example of this concrete segment is depicted in...). Figure 5b (in the middle), the concrete section is post-tensioned using steel strands, and the cylinder 10 is provided with a cylindrical retaining ring 70 at the top (shown in the middle). Figure 6 The cylinder 10 is filled with water, and an inverted dome 40 is provided at the bottom. The cylinder 10 is lined with a high-quality steel liner 11. The cylinder 10 is filled with water, and the piston 30 is within the water volume. The piston 30 is loaded with a weight 31, which is made of a material block with a high bulk density and is symmetrically fixed to the surface of the piston 30. Water is placed above the piston 30 up to the upper horizontal plane of the cylinder described, which is flush with the upper part of the return channel 25. The weights 31 are symmetrically fixed to the surface of the piston and are placed in pairs at diametrically opposite positions in terms of uniform mass distribution during installation.

[0031] Axially, within the cylinder block 10, there exists a high-pressure passage 20 that guides pressurized water to a power generation system 50 made of, for example, a Pelton-type impulse turbine. The high-pressure passage 20 has water inlets and outlets 29 at its bottom, through which water is introduced or extracted from below the piston, depending on the operating cycle. The high-pressure passage 20 is sealed and degassed at its top. Water processed in the power generation system 50 is discharged back into the cylinder block 10 through a return passage 25, which is at atmospheric pressure. For external energy input, the input system 60 includes a high-pressure and variable-flow pump system that draws water from the return passage 25 (above the piston 30) and, driven by the piston 30, introduces it into the high-pressure passage 20, thus raising the piston and accumulating potential energy. The two water circuits are completely separate. The high-pressure circuit begins at the cylinder block base and ends at a turbine access valve (which opens only during the power generation cycle) and a directional valve at the outlet of the high-pressure pump (which opens only during the energy absorption and storage cycle).

[0032] Water is an incompressible liquid and therefore an ideal medium for transferring potential energy. Energy is stored within the system through the vertical position of piston 30. With cylinder 10 filled with water below and above the piston, the pressure in high-pressure channel 29 will be constant regardless of the vertical position of piston 30. To use a small amount of water, the total weight of piston 30 (including load 31) must be high; the higher the total weight of piston 30, the higher the hydrostatic pressure, and therefore the higher the energy stored per cubic meter of water in the system.

[0033] In an exemplary embodiment, the cylinder body 10 is constructed below ground level, at a depth h of approximately tens of meters / between 20m and 100m, and with a diameter D between 10m and 75m. The cylinder body is made of pre-tensioned precast concrete segments 12, which are connected by steel strands 15 and post-tensioned, and are internally coated with a high-quality steel lining 11. Figure 2 The details of the cylinder wall 10 are depicted. A high-quality steel liner 11 exists on the inner surface of the vertical wall of the cylinder. The liner section will be manufactured in the factory and then installed, welded, and straightened on site. This will allow the piston 30 to slide easily and withstand pressure from the horizontal shear zone of the connection between the precast concrete sections 12. The high-quality steel liner, together with the pre-tensioned section (also post-tensioned with steel strands), withstands the circumferential stress in the cylinder 10. A waterproof layer 19 is applied to the outer surface of the vertical wall of the cylinder, which also serves to withstand the expansion and compression of the ground during construction and operation.

[0034] To ensure system integrity under high operating pressures with the lowest possible construction cost, pre-tensioned precast concrete segments 12 are manufactured in a controlled manner at a factory, pre-tensioned before casting, and positioned in the portion outside the cylinder body 10, with holes through which high-quality steel strands 15 will be pulled. The pre-tensioned precast concrete segments are post-tensioned on-site after installation until the required circumferential stress (equivalent to the hydrostatic pressure obtained from the weight load 31 of the piston 30) is reached under the additional resistance of the high-quality steel liner 11, such that the concrete in the wall will only function under compression, regardless of the piston's position, for maximum efficiency. Furthermore, the pre-tensioned precast concrete segments 12 are provided at the edges from the factory with access points for assembly between connecting elements 72 and gap-stretcher holes required for the strand tensioning device. In this embodiment, the strand holes have an internal annular channel / hole shape parallel to the length of the concrete segment 12.

[0035] The assembly design of the prefabricated unit is described in Figure 5a In the middle, precast components—pre-tensioned precast concrete segments 12—are installed in place by means of screw and nut type detachable connecting elements 72. The precast components 12 are installed alternately (vertically staggered) so that the stranded holes are continuous, such as... Figure 5a As described, continuous connection lines are avoided. At piston 30, the hydrostatic pressure below it is very high (200 to 500 bar) and the hydrostatic pressure above it is low (0 to 10 bar), resulting in a consistent / significant circular shear force. To withstand these forces, the pre-tensioned precast concrete segments 12 are assembled alternately and precisely to avoid continuous connection lines and thus reduce the necessary resistance to the connection (and the implied cost). To prevent deformation of the premium steel liner 11, after the premium steel strands 15 are installed and tensioned, the access points of the connecting elements 72 and the tensioning elements of the strands 15, as well as the joints between the elements, are sealed in the field with high-density concrete.

[0036] refer to Figure 6The design depicts a proposed site plan on the land surface (around the upper portion of the future cylinder 10). The foundation 71 is constructed in an annular shape, sized according to the topographical features of the terrain, the dimensions of the cylinder 10, and the proposed future weight of the piston 30 containing the weight 31. On the foundation 71, a dense reinforced concrete slab 70 will be constructed on-site. This slab extends downwards with a cylindrical neck having the same proposed diameter as the cylinder 10 and also contains connecting elements 72 required for fastening / installing the pre-tensioned precast concrete segments 12. The construction will be carried out by excavating downwards in stages, depending on the designed size of the pre-tensioned precast concrete segments 12, to ensure easy access to the bottom of the excavation for the installation of the precast segments 12, the installation of the strands 15, and the installation of the high-quality steel liner 11. Once the designed minimum (bottom) level for installation is reached, the bottom inverted dome 40 will be reinforced with steel bars and cast-in-place concrete will be poured to provide clamping lugs 41 connecting to the steel bars of the inverted bottom dome and to the high-pressure channel 20 to access the water inlet / outlet 29. Space is provided between the clamping lugs 41 for water circulation. The clamping lugs must ensure that the upward force applied by the high-pressure channel 20 is directed towards the steel bars of the bottom inverted dome 40. The inverted dome is designed to use its own system weight to provide the foundation required to anchor the high-pressure channel, thus further reducing construction costs.

[0037] The high-pressure channel 20 is made of high-quality steel (e.g., but not excluding other available variants, steel 1.5423 according to EN 10027-2), with a diameter D between 1m and 10m, and is manufactured in a manufacturing facility in sections between 3m and 12m in length, depending on site access limitations and cost analysis. The steel sections are manufactured and the surfaces are corrected to tolerances better than 1mm. These sections are provided with joint flanges at the ends to allow minimal striations to be exposed to the piston circular water seal / insulating gasket 33. Details of the joint are depicted in... Figure 3 In this configuration, the upper section 21 is assembled to the lower section 22 via a precision tongue and groove joint 26, forming a fixed clamp within the high-pressure channel by means of corresponding flanges 27 and detachable joint elements 25 (e.g., screw and nut type). At the joint between the sections, the flange is provided with a hole, preferably semi-annular, corresponding to a number of rubber washers 24, preferably annular.

[0038] exist Figure 4The design of a heavy-duty piston 30 is shown. The piston is made of steel, manufactured in a factory, and assembled on-site. The piston 30 can be constructed from, for example, steel plate segments having a circular fan shape, with the central tip cut off, assembled to form the designed shape. This piston 30 only bears a uniformly distributed static load, essentially acting as a barrier between two areas with a pressure difference. Therefore, a support mesh made of steel T-profiles is sufficient to prevent piston deformation. The piston 30 is equipped with roller guides 35, which guide the piston within the cylinder to ensure it is in the desired horizontal position during vertical movement. These guides are manufactured on a case-by-case basis, depending on each installation, in both number and size. Figure 4 In the proposed design illustrated herein, the roller guide 35 has a right-angled triangular shape made of steel profile and is mounted on the upper surface of the piston 30. A block (31) of material with a high bulk density is mounted / secured on the piston 30. This block is manufactured in the factory and isolated from water to prevent degradation over time. The block 31 is loaded and unloaded relative to the piston in an order that minimizes the resistance required to prevent imbalance of the piston 30 and thus the guide 35 (during installation and possible maintenance operations).

[0039] On the lower surface of piston 30, on the lower outer edge of the steel liner facing the cylinder block, such as Figure 4 As shown, an integral steel guide 36 will be provided, designed to release pressure on the circular hydraulic insulating washer 32 relative to the steel liner 11 of the cylinder 10 in a gradient manner. Similarly, an integral steel guide 37 will be provided in the central portion of the piston 30 as it travels on the high-pressure channel 20, designed to release pressure on the circular hydraulic insulating washer 33 relative to the outer wall of the high-pressure channel 20 in a gradient manner.

[0040] The electrical energy input (absorption) system 60 differs from the electrical energy generation (production) system 50. This allows for the use of optimized and efficient electro-hydraulic equipment. Electrical energy production is accomplished using impulse turbines, such as Pelton turbines, which ensures low water consumption, thus increasing the energy stored per cubic meter of water. The system size can also be unbalanced in the sense that it allows for completely different input and output levels (e.g., full load during off-peak hours and unloaded during peak hours).

[0041] The power generation system 50 may contain one or more Pelton turbines connected to the generator. The power generation system 50 may be a classic Pelton system, with flow regulation via linear control of the feed valves in the turbines, thus allowing for continuous power production variations between 0% and 100% of the installed capacity. The energy input (absorption) system 60 contains several high-pressure pumps to absorb adjustable amounts of energy and achieve high efficiency. This pump group contains only one or two pumps with variable flow rates, while the remaining pumps have fixed flow rates and pressures, making it cheaper, more efficient, and requiring less maintenance. The energy input system 60 is designed to maximize power transmission efficiency by using fixed-power synchronous motors with fixed power steps and linearly adjustable variable-power motors.

[0042] To continuously absorb electricity in a controlled manner, such as in a wind farm, the energy absorption system (input system) (60) is equipped with several pumps with constant pressure and constant flow rate attached to an electric motor with a fixed rated power and no adjustment element. These pumps are low-cost, low-maintenance, and highly efficient. For continuous adjustment within a range of 0% to 100%, one or two pumps with constant pressure but variable flow rate are used, and the attached electric motor employs a power control system. Compared to a 150% fixed system, these variable systems will have a unit capacity to allow the controller to continuously adjust energy absorption regardless of the direction and rate of change of the power to be absorbed.

[0043] Since the invention has been described with reference to preferred embodiments, it should be understood that many alternatives, modifications, and variations will be apparent to those skilled in the art. Therefore, it is intended to include all such alternatives, modifications, and variations that fall within the spirit and scope of this application, as set forth in the appended claims.

Claims

1. A combined gravity-hydraulic-electric energy storage system, comprising: A heavy-duty piston, placed in a water-filled cylinder, is equipped with a sliding washer to prevent leakage around the piston; and A high-pressure channel connects the water flow from the bottom of the cylinder to the power generation system, wherein... The piston is supported by a symmetrically fixed material block on its surface to achieve a uniform mass distribution. This block serves to accumulate gravitational potential energy by vertically lifting the piston inside the cylinder, which has reinforced concrete walls and an inner surface covered by a steel liner. The piston is guided by roller guides on the cylinder wall and has a circular opening at its center. A high-pressure channel is located on the axis of the cylinder. A sliding washer prevents leakage relative to the steel liner of the cylinder and relative to the high-pressure channel. The high-pressure channel passes through the center of the piston and uses an impulse turbine to guide pressurized water from the base of the cylinder to the power generation system. The high-pressure channel has an elbow at the top and is sealed and degassed at its upper end. Water used in the power generation process is discharged back into the cylinder above the piston at atmospheric pressure through a return channel. An electrical energy input system includes a high-pressure pump with a fixed flow rate and a high-pressure pump with a variable flow rate. The high-pressure pump obtains water from above the piston through the return channel and introduces the water into the high-pressure channel below the piston, thereby causing the piston to rise.

2. The combined gravity-hydraulic-electric energy storage system according to claim 1, wherein the cylinder is a large cylindrical pool, the cylinder being several meters or tens of meters in length, depending on the storage capacity, the cylinder being constructed below ground level, having walls constructed by connecting precast concrete sections in the form of cylindrical shell segments with stranded holes, the concrete sections being installed in place by means of detachable connecting elements and post-tensioned with steel strands, the cylinder having a dense reinforced concrete slab at the top, the reinforced concrete slab extending downwards to a cylindrical retaining ring having the same diameter as the cylinder and resting on a foundation, and having an inverted dome at the bottom, the cylinder walls being lined on the inner side with a high-quality steel liner made of cylindrical liner segments to allow easy sliding of the piston, and on the outer side with a waterproof layer, the waterproof layer having the function of allowing the structure to withstand the expansion and compression of the ground during operation and protecting the structure from water from the ground.

3. The combined gravity-hydraulic energy storage system according to claim 2, wherein the cylinder is provided with clamping lugs for the high-pressure channel, and a water outlet is formed between the clamping lugs and a space for water circulation is provided.

4. The combined gravity-hydraulic energy storage system according to claim 1, wherein the piston is made of steel, factory-machined and installed on-site, and has a factory-machined and water-isolated block of the material and a roller guide serving to ensure its horizontal position mounted on its upper surface, and an integral steel guide is provided on the lower surface of the piston at its edge, the integral steel guide dissipating the pressure on the circular hydraulic sliding washer relative to the steel liner of the cylinder in a gradient manner, and an integral steel guide is provided in the central portion where the piston intersects with the high-pressure channel to ensure the gradient unloading of the pressure on another circular hydraulic sliding washer relative to the outer wall of the high-pressure channel.

5. The combined gravity-hydraulic-electric energy storage system according to claim 1, wherein the high-pressure channel is a cylindrical pipe with at least one elbow at the upper end of the cylindrical pipe made of high-quality steel, the at least one elbow being manufactured in sections and having a joint flange at the end, wherein the upper section is assembled to the lower section by a precision tongue and groove joint, and a fixed clamping is formed inside the high-pressure channel by means of the corresponding joint flange and a detachable joint element, wherein at the joint between the sections, the joint flange is provided with holes corresponding to a number of rubber gaskets.

6. The combined gravity-hydraulic-electric energy storage system according to claim 1, wherein the piston is provided with an integral steel guide, the integral steel guide being designed to release the pressure on the circular hydraulic sliding washer relative to the steel liner of the cylinder in a gradient manner.

7. The combined gravity-hydraulic energy storage system according to claim 1, wherein the piston is provided with an integral steel guide, the integral steel guide being designed to release pressure on the circular hydraulic sliding washer relative to the outer wall of the high-pressure channel in a gradient manner.

8. The combined gravity-hydraulic electrical energy storage system according to claim 1, wherein the energy input system having an adjustable input power range from 0% to 100% is provided with a plurality of constant pressure and constant flow pumps, the plurality of constant pressure and constant flow pumps being driven by electric motors having fixed rated power and no power / speed adjustment and for continuous adjustment within the 0% to 100% range, and wherein the energy input system is further provided with one or more pumps having constant pressure but variable flow, the one or more pumps being driven by electric motors having power / speed control adjustment.

9. The combined gravity-hydraulic energy storage system of claim 1, wherein the power generation system having an adjustable output power range from 0% to 100% comprises one or more Pelton turbines connected to generators, each having flow control within the range of said 0% to 100%.

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