CZ309913B6 - Pumped storage plant for the transfer between the base and floating tank - Google Patents

Abstract

The pumped storage plant consists of a floating tank (7) located in the base tank (2) in the environment of two liquids with different density. There is a height difference (V) between the operating levels (10, 11) of the denser liquid in the tanks (2, 7, 7a). The base tank (2) is the lower tank and the floating tank (7) is the upper tank. The floating tank (7) contains a float (7c) and the tank (7a) for denser liquid, whereas the float (7c) is arranged so that it creates buoyancy to carry the floating tank (7) in the base tank (2). The power plant further contains a pipeline (12) and an energy set (15) to transfer the liquid between the lower and upper tank. The floating tank (7) contains an intermediate piece (7b) to carry the tank (7a) for denser liquid.

Description

Pumping station for pumping between the base and floating reservoir

Field of technology

The invention relates to a pumped storage power plant with a floating tank located in a base tank in an environment of two fluids with different densities.

Current state of the art

Effective balancing of disproportions between consumption and production of electricity, faster development of power plants based on renewable energy sources and limiting the operation of fuel-fired power plants are fundamentally hindered by the complete lack of economically and environmentally advantageous energy accumulators with high performance, capacity and efficiency, which could be built as close to the site as possible consumption and/or production of energy.

Power plants using mechanical methods of accumulating potential energy offer the largest capacity and have the longest lifespan. However, the implementation of existing types of these power plants is only possible under narrowly specific conditions.

Of these, pumped hydro power plants are the most widespread because they show the highest cost efficiency even though they occupy a relatively large volume. In the current design, they are based on accumulating the gravitational potential energy of water by pumping water from the lower stable tank to the upper stable tank. However, these power plants require considerable space in mountainous terrain, and therefore their further construction is increasingly facing resistance due to the legitimate interests of landscape and nature protection. They cannot be built in flat or densely populated areas. Underground water pumping stations are threatened by geological influences.

A well-known solution is an underground water pumping station, which consists of a vertical cylinder with a bypass pipe. It is several hundred meters deep and is filled with water. A heavy concrete and iron piston moves inside the cylinder, sealed against water penetration between the cylinder and the piston. The piston is lowered by gravity and forces water from under the piston through a bypass pipe with a reverse turbine into the space above the piston. In the piston's gravitational potential energy storage mode, the water is then pumped back under the piston and lifts it up. In addition to the frictional losses of the piston in the cylinder, the disadvantage is that the power plant cannot have too large a capacity, as the diameter of the cylinder must be limited for reasons of strength and cost. Considerable maintenance costs for friction surfaces and sealing elements can also be assumed.

A known solution is a floating pumping station according to the invention of EP 3085951, which includes a floating tank that rises or falls in the base tank according to the amount of stored seawater when sailing at sea level; a water turbine located on the inlet pipe in the floating tank generates power by transferring water from the sea into the floating tank, where the water level is made to be lower than the sea level, which is ensured by pumping the water from the floating tank using a fixed pipe, but very in an inefficient manner up to above the upper platform of the floating tank into the airspace above sea level; the connection between the water space of the floating tank and the sea through the pipe is interrupted by this air space, the pump discharge head increases by the height of the air space compared to the height drop on the turbine, and the consumption of electricity for pumping water from the floating tank increases unnecessarily, which reduces the efficiency of the pumping energy cycle.

A floating pumped storage power plant is known according to the invention WO 2013163979 or according to the invention DE 102013015082, containing a floating tank that floats on the surface of the base tank.

At the same time, the floating tank consists of two chambers - the upper and lower chambers, which are firmly connected by construction.

- 1 CZ 309913 B6

The lower chamber is completely submerged in the base tank, it is connected to the air through a ventilation chimney, the upper chamber is fully open to the air at the top, it is located at the level of the water level in the base tank.

Both chambers thus simultaneously form a combined float, which enables the floating tank to float on the level of the base tank.

The two chambers of the floating tank are interconnected by a vertical channel and a turbine, with water flowing in this vertical channel only in one direction down to the turbine.

The upper chamber of the floating tank is connected to the base tank by a side channel at the level of the water level in the base tank, so the upper chamber is functionally part of the base tank. The side channel can be closed so that the floating tank does not sink when the upper chamber is overfilled.

When submerging the floating tank, the upper chamber is spontaneously filled through the side channel from the base tank, and when the floating tank emerges, the water flows spontaneously through the side channel from the upper chamber to the base tank, while due to the hydrodynamic resistance in the horizontal channel, a height difference between the water level in the upper chamber of the floating tank arises and the water level in the base reservoir, which is the source of losses in the energy balance of pumping.

The lower chamber is connected to the base tank at the level of its bottom by means of a side channel and a pump, through this side channel water flows in one direction only from the pump to the base tank.

The lower chamber of the floating tank is the lower tank and the base tank is the upper tank. Here, the upper chamber of the floating tank is part of the basic tank, it is not a separate, independent, full-fledged upper tank compared to the lower chamber of the floating tank in both turbine and pumping mode, therefore the floating tank moves vertically during pumping.

Pumping is carried out between the base tank and the lower chamber in a floating tank, which submerges when filling the lower chamber with water from the base tank in turbine mode and emerges when water is pumped from the lower chamber to the base tank.

While in the pumping mode the connection of the base tank and the lower chamber of the floating tank is direct, immediate, in the turbine mode the connection of the base tank and the lower chamber of the floating tank through the turbine is not direct, immediate, it is interrupted, which reduces the usable hydrostatic drop:

- the filling of the upper chamber of the floating tank with water from the base tank using the side channel is done here freely, without energy use, while in the upper chamber the water level connects with the air and thus breaks the water column between the water level in the base tank and the water level in the upper chamber ,

- from the upper chamber, the water is passed through a vertical channel directly, immediately, with energy use through the turbine to the lower chamber.

During pumping operation, water is pumped out of the lower chamber of the floating tank by the pump using the side channel directly, i.e. directly into the base tank, while the water from the upper chamber flows freely through the side channel into the base tank without energy use.

At the same time, the floating tank emerges from the lower to the upper operating position.

During pumping operation, the hydrostatic drop (discharge head) is formed by the height difference between the water level in the base tank and the water level in the lower chamber.

During turbine operation, water from the upper chamber of the floating tank is transferred through a vertical channel to

- 2 CZ 309913 B6 lower chambers through the turbine, while water from the base tank flows freely through the side channel into the upper chamber without energy use.

At the same time, the floating tank dips from the upper to the lower operating position.

During turbine operation, the hydrostatic head (discharge head) is formed by the height difference between the water level in the upper chamber and the water level in the lower chamber.

A pumping power plant according to the invention of EP 2418375 with a floating tank for storing water is known, while the energy device is connected to the floating tank by a hinged or telescopic pipe and is vertically movable so that, due to easy accessibility for maintenance, it remains at the level of the basic upper tank even when the floating tank is moving. However, the water level in the base tank is higher, i.e. it has a higher energy potential than the water level in the floating tank. As a result, the difference in height between the water levels in the base and floating tanks is processed by the energy equipment on its negative side, i.e. in the area of the suction pipe, so that the permissible difference in height is greatly limited, so that when water is transferred, cavitation does not occur in the energy system or rupture of the water column at the suction height above the water level in the floating tank. Therefore, only a fraction of the difference in height from the total depth of the base tank can be used with the mentioned solution.

The water level in the base tank is at most a few meters higher, i.e. it has a higher energy potential than the water level in the floating tank. In the pumping mode, water is sucked from the interior of the floating tank using an energy device floating on the water level in the base tank. The permissible transfer height difference is limited by the suction height, so that during water transfer, the water column in the pipe above the water level in the floating tank does not break. Therefore, only a fraction of the difference in height from the total depth of the base tank can be used with the mentioned solution.

A pumped storage power plant according to the invention US 2018156185 is known, which mainly contains two necessary parts:

- a conversion chamber that floats on the surface of the base tank and works as a compressor/turbine to pump air between the atmosphere and a stable pressure tank (compressed air reservoir),

- a stable pressure tank for accumulating compressed air, which is permanently submerged and anchored to the bottom of the base tank, while the two tanks are connected by pipes.

The essence of the above-mentioned invention is also a method of converting electrical energy into aeraulic energy and vice versa, in which air is compressed from the atmosphere in a floating conversion chamber and stored in a compressed air reservoir, or exits from this reservoir into a conversion chamber, where it expands into the air.

The conversion chamber is actually a combined pneumohydraulic energy device - an air-driven single-acting piston compressor/motor for pumping air between the atmosphere and the compressed air reservoir, where the hydraulic piston serves as the water level driven by the pump/turbine water system pumping water between the conversion chamber and the base tank. Since the conversion chamber is supposed to be about 100 times smaller than the compressed air reservoir and the compression ratio is assumed to be high (about 10, which roughly corresponds to a depth of around 100 m in isothermal compression), the compression must be at least two-stage and with a higher number of conversion chambers , so that it is possible to ensure the accumulation or reverse production of electrical energy continuously for a longer period of time and without large fluctuations in performance.

A pumping station according to the invention CN 206721844 is known. A closed stable tank placed

- 3 CZ 309913 B6 on the bottom of the sea, submerged completely or partially protruding above the level of the base tank, is filled with water through a turbine located at the bottom of the stable tank and sucked out by a pump located on the upper platform of the stable tank. The stable tank serves as the lower tank, the base tank serves as the upper tank. The maximum difference in liquid levels is determined by the permissible suction height of the pump.

A pumped storage power plant according to the invention US 2014033700 is known. A floating tank in the function of a lower tank or an upper tank is vertically movable in a base tank, which serves accordingly as an upper or lower tank.

In cases where the floating tank is a bottom tank, the sum of the discharge head and the operating lift is limited by the submergence depth of the floating tank.

In cases where the floating tank is a top tank, the discharge head is limited by the depth of the float (floating tank) because the water tank is directly attached to the float.

A pumping station according to the invention GB 1601398 is known. Three tanks are used here. A stable tank is inserted into the water in the base tank, which is freely exposed to the air at the top. In this pair, the basic tank is the upper tank and the inserted stable tank is the lower tank in relation to it.

In the inserted stable tank, a vertically movable floating tank is placed in the water. In this pair, the embedded stable tank is the upper tank and the floating tank is the lower tank relative to it.

Instead of a simple transfer between the inserted stable tank and the base tank, there is a complicated and therefore more lossy transfer via the floating tank, i.e. gradually between the floating tank and the inserted stable tank and then between the inserted stable tank and the base tank.

Discharge height is limited by the immersion depth of the embedded stable tank and the immersion depth of the floating tank.

The mentioned solutions of pumping stations with a floating tank, whether lower or upper, only achieve such a value of discharge head, which in the optimal design is at most equal to the draft of the floating tank in the base tank, so the capacity of these pumping stations is relatively low.

At the same time, the walls of the floating and stable tanks that make up the lower tank are extremely disadvantageously stressed by the external overpressure and the corrosive effects of water from the base tank, in addition, it is usually necessary to increase the buoyancy of the lower floating tank with an additional load or mechanical device to achieve the necessary draft and thus to achieve the necessary discharge heights.

Their construction is therefore relatively expensive, with a rather short lifespan, especially for deeper tanks.

Overall, the mentioned pumped-storage power plants with a floating tank are not very economically advantageous, despite the high prices of electricity, therefore this type of pumped-storage power plants is not very widespread.

The task of the invention is to improve the pumping power plant with a floating tank by creating a light, stable and efficient structure so that its discharge height is not limited by its immersion depth and at the same time to reduce its stress even at a large immersion depth, in order to achieve a many times higher capacity, service life and economic advantage pumped storage power plants.

The essence of the invention

The invention solves the mentioned problem with a pumped storage power plant that contains a floating tank located in a base tank in an environment of two fluids with different densities, while there is a height difference between the operating levels of the denser fluid in the tanks, where the base tank is the lower tank and the floating tank is the upper tank, further floating the tank contains a float and a tank for denser

- 4 CZ 309913 B6 fluid, while the float is arranged to create buoyancy for carrying the floating tank in the base tank, and the power plant further contains pipelines and energy equipment for pumping the fluid between the lower tank and the upper tank, the essence of which is that the floating tank contains an intermediate piece, with the bottom-shift arrangement, it consists of: a float, an intermediate piece and a tank for a denser liquid, while the intermediate piece is arranged to carry a tank for a denser liquid.

The total potential energy is accumulated in the pumping station in the form of positional and buoyant energy of the floating tank and in the form of positional and pressure energy of the fluids in the floating tank. Pumping one of the fluids can change not only the potential energy of this fluid and the floating tank, but also the potential energy of the other fluid. One or both fluids can be pumped sequentially or simultaneously.

It is clear from the further description that the floating tank is designed as an upper tank in relation to the base tank.

The total operating height difference of the denser liquid levels is formed by the height difference between the liquid level in the upper tank and the liquid level in the lower tank.

The energy system for pumping a denser liquid is connected by means of a pipe on the discharge side to the upper tank and on the suction side to the lower tank.

Thus, the power plant for pumping the denser fluid is connected to the base tank and/or the floating tank by means of a pipe and arranged in height so that the operating height of the denser fluid in the pipe is higher on the side of the power plant connected to the upper tank than on the side connected to the lower tank.

The height difference is therefore processed primarily by the overpressure, discharge side of the power plant, not by its underpressure, suction side, which makes it possible to achieve a high overall operating height difference and not to limit the overall operating height difference to the suction height, which is limited to only a few meters, when there is still no to cavitation in the power system or to the rupture of a column of denser fluid in the suction pipe.

The term operating height is used to express a situation where the pipeline is filled with a denser liquid and a difference is created between the levels of the denser liquid in the upper tank and the lower tank that can be readily used for pumping.

For this purpose, a valve is installed in the pipeline of each pumped power station to operationally stop or regulate the flow of the pumped fluid due to the situation in the energy network or to prevent the unwanted flow of the pumped fluid (especially to leak the fluid from the upper tank to the lower tank) e.g. in the event of a power failure sets.

This distinguishes the situation that occurs during repairs or in the event of a fault, when there is an intentional or accidental release of liquid from the pipeline and the liquid levels in the upper tank and the lower tank are thus equalized and the pumping station is taken out of operation.

However, the mentioned situations are common for every pumped storage power plant and do not contradict its essence.

The difference in height of the liquid levels in the basic and floating tanks, i.e. the hydrostatic pressure difference acting on the power system, hardly changes during the pumping cycle.

Advantageously, the outer horizontal cross-section of the submerged part of the floating tank is equal to the inner horizontal cross-section of the upper part of the floating tank for the denser liquid in order to maintain a constant height level of the level of the denser liquid in the base tank and a constant height level of the level of the denser liquid in the floating tank and thus a constant height difference between these levels .

- 5 CZ 309913 B6

The movement of the floating tank in the base tank takes place at the interface of two working fluids with different densities. Due to gravity, the thinner and therefore lighter fluid stays above the surface of the denser and therefore heavier fluid and the floating tank floats on top of the heavier fluid in the base tank.

Liquids with different densities are preferably liquid as a liquid with a higher density (hereinafter referred to as liquid) and gas as a liquid with a lower density (hereinafter referred to as gas).

Tanks contain space for heavier and lighter fluid, e.g. liquid space and gas space.

The base tank can be open to the environment or closed.

In a power plant with an open design of the liquid space of the base tank, ordinary or partially treated water, preferably treated by filtering, can be used as a liquid. In the closed design of the liquid space of the basic tank, the water can advantageously be thickened with soluble or insoluble substances, whereby higher transmitted powers can be achieved, and it can be modified to reduce the erosive or corrosive effect on the components of the hydroelectric power plant, or another suitable liquid can be used.

In a power plant with an open design of the gas space of the base tank, air is preferably used as gas. In a closed design, the gas space above the liquid level in the base tank is separated from the surrounding atmosphere, and the gas pressure in the base tank does not have to be equal to the pressure of the surrounding atmosphere. An inert gas can be advantageously used here, preferably nitrogen, which is more expensive, but reduces the corrosion of hydroelectric power plant components.

The base tank is advantageously designed to be stable.

An open basic stable reservoir can advantageously be formed by a sea or a river, an existing or new artificial body of water, a lake, e.g. at the site of an excavated surface mine, or it can be formed as a pit below the surface or as a pit open to the surface, preferably it can be formed on the surface as a sunken reservoir, whereby the rock excavated when the tank is dredged can be advantageously used to create an embankment around the depression in order to increase the water level and thus the depth of the tank. Areas with a high groundwater level or areas that are permanently flooded, e.g. in the Netherlands, can advantageously be used for the construction of pumping stations according to the invention.

The basic tank can advantageously be formed in the shape of a vertical cylinder.

The simple shape of the floating tank as a cylinder with a vertical longitudinal axis and with a regular or irregular base is advantageous for stabilizing the performance of the power plant.

The floating tank can have a simple construction, it can advantageously copy the shape of the base tank with its walls and bottom, in order to make the most of the volume of the base tank for pumping and, for example, to allow the floating tank to be placed on the bottom during repairs, it can be made very voluminous, at the same time well balanced and with a large draft according to the size of the base tank, especially if the base tank is formed by the sea.

It is advantageous to leave sufficient free water space around the floating tank for greater resistance to damage in case of lateral displacement of the floating tank in strong wind and waves or during an earthquake, when pressure shocks from the base tank are better dissipated around the floating tank.

For the amount of accumulated potential gravitational energy of a floating tank, only the vertical component of the movement of this tank is authoritative.

If the pumped fluid is a denser fluid, the amount of potential energy stored in the

- 6 CZ 309913 B6 floating tanks depends mainly on the difference in height of the denser liquid levels in the base and floating tanks, on the amount of pumped denser liquid and on the working lift of the floating tank.

The potential energy in the pumping station is in the form of the positional and buoyant energy of the floating tank and in the form of the positional and pressure energy of the fluids in the tanks, the ratios of individual types of energy change during pumping.

The weight of the floating tank means the sum of the weight of the construction and equipment of the floating tank and the weight of the additional load.

The height relationship of the tanks is defined here so that the liquid level in the upper tank is higher than the liquid level in the lower tank.

The upper floating tank is formed in such a way that its liquid space, i.e. the tank for the denser liquid, is formed in the upper part of the floating tank.

According to the invention, the lower part of the floating tank forms a float, an intermediate piece is built on top of it, and a tank for a denser liquid is built on top of it.

Advantageously, the liquid space in the upper part of the floating tank is created at a height that can be many times the height of the liquid space.

The advantage of this arrangement is that the empty floating tank can have, depending on the strength of the material used, a relatively very light construction. Additional load is undesirable here.

With the same usable depth of the basic tank as when using the lower floating tank, a significantly higher accumulation capacity of the floating tank can be achieved when using the upper floating tank according to the invention.

It is possible to choose the optimal variant among the extreme options of this design:

- lighter and lower floating tank and larger pumped water filling, - heavier and high floating tank and smaller pumped water filling.

Sufficient space above the level of the base tank is required for the upper part of the floating tank to emerge when it is emptied.

The center of gravity of the floating tank is above the liquid level of the base tank and, especially during filling and accidental lateral loading, it can become unstable due to an incorrect design solution.

This floating tank, with its slimmer shape, therefore requires a solid line to ensure stability.

The stability of the floating tank against overturning can be increased on the principle of a catamaran so that the floating tank will have, if possible, a width greater than its height above the surface, while the specific ratio of these quantities depends mainly on the ratio of the weight of the pumped water filling and the weight of the floating tank and on the choice permissible tilting of the floating tank.

Advantageously, dividing the liquid part of the floating tank with built-in partitions or creating a connected system of smaller tanks slows down or prevents the overflow of a large volume of water in the floating tank and thus further improves the stability of the floating tank against overturning.

Internal partitions and/or chambers which are also useful as reinforcements of the floating tank to increase its strength or to reduce the thickness of the peripheral walls of the floating tank.

- 7 CZ 309913 B6

At the level of the upper and lower edges of the floating tank, at the level between the water tanks and spacers, and at the level between the floats and spacers, the floating tank can be reinforced with horizontal flanges, which significantly strengthen the bending stiffness of the floating tank, optimally to the point that it will be reduced the need to reinforce the modules with internal vertical reinforcements.

For the purposes of the pumped storage power plant, it is desirable to make the best possible use of the volume of the base tank.

The float is a part of the module that is mostly submerged in the base tank and its buoyancy determines the weight of all parts of the module. The float is a pressure vessel, preferably a closed pressure vessel, it is stressed mainly by the external overpressure of the water and the weight of the supported parts of the module. The lateral external overpressure of water acting on the walls of the float increases linearly with the depth of immersion of the float. Floats may also have inner rings to reinforce against external overpressure.

The floats are preferably filled with gas, preferably an inert gas, which limits the corrosion of the float material.

For the sake of the largest possible capacity of the floating tank, it is necessary that the construction of the modules be as light as possible, and thus their height can be as high as possible.

The float is therefore preferably filled with gas, preferably nitrogen, so that its internal excess pressure is equalized as much as possible with the largest external overpressure of water during immersion in the base tank, preferably to an internal overpressure that is equal to the largest external overpressure of water, which corresponds to the full immersing the float. The float does not need to be reinforced against collapse by external overpressure as thoroughly as in the case of one-sided external overpressure loading, and it can be considerably lighter.

The internal air space of the water tanks above the water level is freely connected to the atmosphere by means of a venting pipe, so that the internal overpressure in the water tanks is caused only by the hydrostatic pressure of the water filling and to ensure a constant height of the water column to the hydropower system throughout the working stroke of the floating tank, so the power losses of the controls are minimized.

The gas space above the liquid level in the floating tank can advantageously be opened to the gas space of the base tank. When pumping liquid in order to change the height position of such a floating tank, the pressure difference in the liquid energy system is practically constant throughout the working stroke of the floating tank, so that the power losses of the controls are minimized.

Similarly, the air space between the floats above the water level in the base tank is freely connected to the atmosphere by means of ventilation holes, so that the external overpressure on the floats is caused only by the hydrostatic pressure of the water filling and to ensure a constant height of the water column to the hydropower system.

The space between the water tanks as well as the entire space inside and outside the spacers can also be filled with nitrogen or other suitable gas to increase corrosion protection.

The modules are advantageously manufactured with a diameter of up to 3.6 m, so that their parts can be easily transported from the manufacturer by rail.

Therefore, by closing and reinforcing the space between the modules, the efficiency of the use of space and the capacity of the floating tank for accumulating potential energy will be increased by 20 to 30%.

At greater depths, it is advantageous to divide the float in height into several compartments, which are separated from each other by a pressure partition, preferably in the shape of an arched bottom.

Each section of the float, also known as a segment, is filled with gas with an advantage to the internal excess pressure, which is

- 8 CZ 309913 B6 equalized as much as possible the external overpressure of the water corresponding to its greatest specific depth of immersion in the base tank.

As the placement depth increases, the segments are filled to a higher internal overpressure, which is equalized with the external overpressure, and the wall thickness of the segments can be significantly less than if there was a uniform internal overpressure throughout the float corresponding to the maximum immersion depth in the base tank. This further significantly reduces the weight of the float.

The internal overpressure of the float and its segments can be advantageously higher than the external overpressure of the water corresponding to their greatest specific depth of immersion in the base tank, which increases the resistance of the float and its segments to accidental external overload by hitting the bottom or to sabotage.

In the upper days of the segments, it is advantageous to create transition overpressure chambers for the possibility of maintenance workers entering the segments with different overpressure. The chambers must be equipped with reliable closures that prevent the leakage of filling gas between the segments.

For the purposes of a floating tank, it is advantageous to use as much of the area and depth of the base tank as possible.

The floating tank can advantageously be assembled from modules with a uniform immersion depth of the floats, and thus with a uniform building height of the modules according to the chosen depth level in the basic tank. The deeper the level for deeper immersion of the floats is chosen, the smaller the area of the floating tank will be, since the areas of the depth levels of the base tank decrease towards the bottom of the base tank. However, as the area decreases and the depth increases, the stability of the floating tank decreases, which must therefore have a smaller discharge height, and thus the specific price and investment requirements of the floating tank may increase adversely. All the energy systems in this floating tank can be of the same power, because they all have the same discharge height.

The floating tank can advantageously be assembled from modules with different immersion depths of the floats according to the depth profile of the base tank, and therefore with different building heights of the modules, so that not only almost the entire width but also almost the entire depth of the base tank can be used for the purposes of the floating tank, i.e. almost the entire volume of the base tank. This design allows the axis of the center of gravity of the floating tank to be identical to the axis of buoyancy of the floating tank. At the same time, due to the large width of the floating tank, its stability can be well ensured even with a large construction height of modules with a deeper draft of floats. For each group of modules with the same construction height, a corresponding group of energy systems with the same displacement height can be available. It is advantageous to fill and empty tanks of different heights simultaneously and proportionally in order to minimize the shear stress in the stiffeners between the differently loaded modules.

The lower bottoms of the floats of different heights are preferably equipped with openings with closures for the possibility of flooding the inner space of the floats to balance the position of the floating tank, e.g. during assembly or during repairs, or in the event of a failure of the floating tank.

A pumped storage power plant with a lower base tank and an upper floating tank can be advantageously operated in such a way that by pumping liquid from the base tank into the liquid part of the floating tank with the help of an energy system, this floating tank sinks under the action of gravity against the buoyancy of the gas part of the floating tank (the consumption of electrical energy accumulates positional energy of water) and by draining the liquid from the floating tank into the base tank with the help of an energy system, the floating tank emerges due to buoyancy (electricity is produced by consuming the water's positional energy).

Alternatively, the plant may be operated with liquid space at the top of the floating tank depending on weather conditions, particularly wind speed, and the current depth of water in the base tank.

- 9 CZ 309913 B6

In the power plant, tank spaces with different energy potential are connected by paths for energy transmission.

In general, the path for conducting the liquid or gas can advantageously be formed by a pipe. The path for conducting gas or the gas path can also be called an air path, if the gas is compressed air, or a ventilation path, if it connects the air space of the tank freely to the atmosphere.

Pipelines for power transmission in the power plant preferably directly connect the spaces of the base and floating tanks containing the pumped liquid. For example, if the pumped liquid is a liquid, then during pumping by the pump, the discharge pipe connects the liquid spaces of the floating and basic tanks immediately, i.e. directly, without interrupting the displacement water column by the gas space. Thus, the consumption of electrical energy for overcoming the height difference between the liquid levels in the floating and base tanks is reduced to a minimum. Similarly, when the liquid is transferred from the higher level of the upper tank through the turbine, the liquid pipeline is opened directly below the lower level of the lower tank, and thus the height drop is maximally used for the production of electricity.

The path for conducting liquid or gas can advantageously be created directly through the walls of the tank.

The path for conducting the liquid is then preferably created in such a way that the floating tank has no bottom and is submerged by the walls below the level of the liquid in the base tank, the path for conducting air is preferably created in such a way that the floating tank does not have a ceiling and is open to the air or to gas space above the base tank level.

A path for conducting liquid or gas becomes a path for energy transmission if it is connected to an energy system and is closable. The liquid path for energy transfer is connected to the liquid energy system, the gas path for energy transfer is connected to the gas energy system.

The power plant according to the invention accumulates potential energy mainly in the floating tank and in the connected paths for energy transmission. In particular, for this purpose, each energy transfer path according to the invention is closable, i.e. includes at least one closure that allows for the accumulation of potential energy by blocking the flow of fluid between the reservoirs.

The liquid or gas path preferably includes a shut-off and/or regulating fitting, preferably a valve, preferably a non-return valve or non-return flap in the case of single-acting energy transmission.

Advantageously, different paths and corresponding closures can be combined to accumulate potential energy. The same or a different cap can be used to release the accumulated energy, or other way than to accumulate energy.

The gas power plant is used when the pumped liquid is gas, it can be advantageously placed in the upper part of the floating tank above the liquid level, so that it is not so much exposed to possible aggressive effects of the liquid and is easier to reach for maintenance. In the floating tank, a gas space of the required volume is created above the liquid level. For the possibility of accumulating the potential energy of the floating tank by accumulating the pressure energy of the gas, the gas space of the floating tank is preferably connected by means of a closable gas path to the gas space of the basic tank, preferably with air if the basic tank is open. A tank filled with compressed gas is then called a pressurized gas tank or also a compressed air tank, if the compressed gas is air.

Air pressure energy can be created, i.e. increase or decrease the air pressure in one tank above or below the value of the atmospheric pressure or the pressure in the other tank, preferably with a compressor or a vacuum pump with a closed liquid path or by pushing or extracting liquid into or from

- 10 CZ 309913 B6 compressed air tanks by pump or reverse turbine.

When pumping gas, the liquid space of the floating tank can advantageously be opened to the liquid space of the base tank, so that the pressure difference in the gas energy system during the working stroke is constant, so that the power losses of the controls are minimized.

Changing the height position of the pressurized gas floating tank can be advantageously performed by pumping the liquid, during which the gas compression in the floating tank changes. By pumping liquid from the base tank with a pump into the floating tank, the floating tank is submerged and the gas in the closed gas space above the surface of the floating tank is compressed. By passing the liquid through the turbine from the floating tank to the base tank, this floating tank emerges and the gas expands above the surface of the floating tank.

Accumulation of gas pressure energy in the reservoir is part of an energy cycle that includes polytropic gas compression and expansion, which are thermodynamic changes that are irreversible mainly due to the predominant removal of heat from the gas to its surroundings. Heat losses reduce the efficiency of energy storage.

To improve the thermodynamic efficiency of the compression cycle, it is advantageous to recover the compression heat, in other words, to accumulate the compression heat of the compressed gas and use it during expansion or during gas withdrawal, polytropic changes then approach adiabatic changes. The power plant according to the invention can advantageously contain a device for recovery of compression heat. Compression heat is also accumulated in the pumped liquid, which is especially advantageous when the liquid is pumped between tanks in a closed cycle. Heat losses accumulated in fluids are also reduced by insulating tanks and pipes.

When accumulating the pressure energy of the gas in a tank with an open liquid level, another disadvantage is that the gas from the space above the liquid level is gradually absorbed in the liquid in proportion to the excess pressure and is removed by the pumped liquid, as a result of which its density decreases as its volume increases, and the power plant's working cycle becomes pressure can be disturbed to such an extent that pumping stops after a number of cycles. As the temperature increases, the liquid absorbs the compressed gas less.

In order not to reduce the volumetric efficiency of the pumping cycle by reducing the volume of gas in the closed pressure tank, for example by cooling or absorption in the liquid or loss through leaks, the power plant according to the invention preferably contains a device for replenishing gas from an external source, which is formed preferably by a compressor or preferably by a pressure vessel with compressed gas and closable gas pipe. However, adding gas also reduces the overall efficiency of the energy cycle.

The tank can advantageously contain a separate space for the compressed gas, which therefore does not have direct overpressure contact with the liquid level in the tank and cannot dissolve in the liquid.

Advantageously, in the pressure tank, a separate space for compressed gas is created by a flexible, preferably collapsible membrane, preferably it is formed by a membrane bag, whereby the spaces for liquid and gas are completely separated.

In the pressure tank, a separate space for the compressed gas can be advantageously created by an auxiliary pressure vessel containing an auxiliary gas energy system. During the filling of the pressure tank with liquid, the gas from this tank is forced into the auxiliary pressure vessel by the auxiliary compressor, and when the liquid is exhausted from the pressure tank, the compressed gas is discharged from the auxiliary pressure vessel through the auxiliary gas turbine.

A power plant with a compressed-air floating tank, where the pumped liquid is gas, can advantageously have the base tank created as an annulus only for the necessary movement of the walls of the floating tank, therefore the amount of liquid needed to ensure the movement of the floating tank is minimal here.

- 11 CZ 309913 B6

When excavating this base reservoir, the amount of excavated rock is also greatly reduced.

The power plant according to the invention contains a liquid and/or gas energy system in which electrical energy is consumed to accumulate potential energy and electrical energy is produced from the consumed potential energy.

The liquid power system preferably contains a pump for converting electrical energy into liquid potential energy and further contains a liquid turbine for converting liquid potential energy into electrical energy. The transfer of liquid by the hydropower system between the tanks is carried out by means of a liquid pipeline. The turbine and pump can be connected in parallel to a common fluid line or they can be connected separately, the turbine to the supply line and the pump to the discharge line. The power plant can include a reverse turbine that can work in both turbine and pump mode, for example a Francis turbine. A turbine can be connected to a generator, a pump can be connected to a motor, a reverse turbine can be connected to a motor-generator.

The gas power plant preferably contains a compressor, fan or vacuum pump to convert electrical energy into gas pressure energy and further contains a gas engine, for example a gas turbine, for air an air turbine, to convert gas pressure energy into electrical energy, or contains a reverse gas turbine which can work in both turbine and compression mode. The transfer of gas by the gas power plant between the tanks is carried out by means of gas pipelines. A parallel or serial connection to the gas pipeline can be made analogously to the liquid energy system.

In a power plant, where the accumulation of gas pressure energy in a floating tank takes place during pressure or flow changes during the energy cycle, the demands on the regulation of the energy system increase, which also reduces the effectiveness of this variant of the invention.

The performance of the energy system is advantageously adjustable. The power plant according to the invention can advantageously contain several energy systems of the same or different power for better regulation and for grading the power of energy accumulation or production or even to increase the reliability of operation.

The power system also includes other usual accessories, such as equipment for adjusting the parameters of electrical energy and for its transmission to or from the point of consumption and equipment for damping hydraulic, mechanical or electromagnetic shocks and oscillations. A suction basket or combs in the water supply pipe or a suction filter in the air supply pipe to the energy system are also assumed.

The power plant preferably includes a machine room in which the energy equipment is located.

The engine room or just the power system of the hydroelectric power plant according to the invention, e.g. the water power system, can be advantageously directly exposed to the water environment, which is the usual design for submersible pumps or turbines, or can be advantageously placed in a pressure casing, filled with air or other, preferably inert, gas or liquid, preferably an inert liquid, so that they are protected from the outside against overpressure and other adverse, especially corrosive, effects of the water environment. Advantageously, the liquid or gas filling of the pressure housing is compressed so that, through this filling, the external hydrostatic pressure on the machine body is at least partially equalized with the internal hydrostatic pressure, thus reducing the stress on the machine and the pressure housing.

The transmission of electrical energy between the power system and the electrical network can be advantageously solved with a moving cable or, preferably, with the help of a trolley.

The power plant according to the invention advantageously contains security devices, e.g. limit switches, for

- 12 CZ 309913 B6 definition of the position and movement of the floating tank.

The power plant according to the invention advantageously contains a guiding device for guiding the floating tank along a determined trajectory in the area of the base tank. The guiding device ensures smooth guidance of the floating tank against yawing, swaying and overturning, caused for example by its own inertia, waves, water currents or wind, preferably in the form of a sliding and/or rolling and/or articulated device, in a large base tank preferably as guide frame or parallelogram, fixed, for example, to the bottom of the basic tank.

The perfection of the guidance also depends on the number of degrees of freedom of the guiding device. Advantageously, the guiding device consists of a cable guide, whereby the guiding ropes are preferably fixed to the bottom and to floats on the surface of the base tank, whereby the floats are preferably connected to each other and preferably horizontally stabilized. A rope anchored to the bottom of the base tank and tensioned by the buoyancy of the float does not allow the float tank to be guided with exactly one degree of freedom, but as it is a self-centering device, it can be quite close to that degree.

The floating tank may be equipped with equipment, preferably marine engines, to maintain its position in the base tank and/or to move it to, for example, a dock for repairs.

The power plant preferably contains a blocking device, preferably a stop, preferably a spring-loaded one. The blocking device can preferably be self-acting, preferably remotely controllable.

This blocking device is used to define the position of the floating tank in the specified place of the base tank, it preferably ensures the position of the floating tank within the limits required by the operating cycle, e.g. in the extreme position, it preferably prevents the floating tank from landing on the bottom of the base tank and thereby damaging it.

The blocking device can advantageously serve to stabilize the floating tank in the base tank, preferably in the upper operating position, which enables further accumulation of the potential energy of the fluid by pumping it between the tanks and thereby expanding the operating methods to increase the capacity of the pumping station.

After the floating tank is stabilized, only the potential energy of the fluid is accumulated in the stabilized floating tank by pumping the fluid between the tanks, while the immediate pumping takes place in such a way that

- by pumping fluid from a place with a lower energy potential in the first tank directly to a place with a higher energy potential in the second tank with the help of an energy system during the consumption of electricity, the potential energy of the fluids in the stabilized floating tank is accumulated and

- by transferring fluid from a place with a higher energy potential in the second tank directly to a place with a lower energy potential in the first tank using an energy system, i.e. by consuming the potential energy of the fluids in the stabilized floating tank, electrical energy is produced.

The hydrostatic pressure drop, i.e. the level difference, changes during the operation of the stabilized tank in the same way as in the usual pair of stable tanks, i.e. when pumping water from the lower tank to the upper tank, the difference in their levels increases, when transferring from the upper tank to the lower tank, the difference in their levels decreases, which means performance variability or increased demands for its regulation.

Stabilized tank blocking stops carry the full buoyancy of an empty tank or, on the other hand, the full weight of a full tank, which means significant stress both in the design of these stops and in the structure of the stabilized tank.

However, the liquid energy equipment must be located so as not to reduce the processed

- 13 CZ 309913 B6 height difference of levels in the reservoirs of the power plant.

The power plant is connected to the floating tank through a power transmission pipe and is always located at or below the level of the bottom tank.

The location at the level of the lower tank level means the location at most at such a height above the level in the lower tank that there is no rupture of the liquid column in the power system and in the liquid pipeline.

The energy system of the hydroelectric power plant according to the invention preferably moves in line with the floating tank, it can advantageously be connected to the floating tank. With this design, the pressure difference in the liquid energy system during pumping is almost constant, and the energy potential of the floating tank is thus best used.

Advantageously, the power plant is mounted on the outside of the floating tank, making it more accessible for maintenance. However, the asymmetric location of the power system on the floating tank and the resulting fluid flow can be the cause of unwanted deflections of the floating tank in the base tank, which must be compensated for, for example, by a guiding device or by suitable balancing of the floating tank.

According to another feature of the invention, the power system can be located outside the floating tank.

The energy system of the hydroelectric power plant according to the invention is preferably located in a pontoon or other floating device or is preferably connected to a floating tank preferably by means of a sliding or articulated device, while at the same time it is movably connected to a pipe for transferring fluids between the tanks, and this pipe it is advantageously flexible, hinged or telescopic. As the power plant moves at the level of the water in the lower tank, it is more easily accessible for maintenance.

In this context, the energy system can advantageously be firmly connected to the base tank in which the mobile tank is located, it is preferably located on a structure attached to the bottom of the base tank, preferably in a hollow tube, or it is preferably located on the bank of the base tank or preferably in a pontoon or in another floating device also located in the base tank, while it is connected to the floating tank by means of a flexible pipe, preferably the pipe is made of plastic, preferably reinforced.

The advantage of this design can be better access during assembly and maintenance, the disadvantage is longer and more complex paths for energy transmission, which is associated with energy losses, or with a lower service life of flexible pipes.

The pumped-storage power plant preferably contains an access path to the power plant, preferably in the form of a pipeline, preferably contains transport equipment, preferably a rope or rack-and-pinion device, for the transport of people and material for the assembly and maintenance of the power plant.

The floating tank preferably has a hydrodynamic shape and a smooth surface, which reduces the resistance to the movement of the floating tank in the liquid and thereby increases the efficiency of energy accumulation and production.

However, there are situations where the low hydrodynamic resistance of a floating tank is a disadvantage. Therefore, the floating tank preferably contains a hydrodynamic motion damper, a stabilizer, the purpose of which is to increase the hydrodynamic resistance and thereby slow down the movement of the floating tank, especially to dampen its swaying on the surface. The damper is preferably attached to the bottom of the floating tank so that it remains below the surface as much as possible during rocking of the floating tank, even if the floating tank or part thereof emerges to the upper operating position. The damper has a shape that imposes the greatest possible hydrodynamic resistance, preferably in at least one direction of movement, for example when completing the operating stroke of the floating tank to the extreme operating position, preferably in both directions of the given direction of movement,

- 14 CZ 309913 B6 for example to limit the height swing of a floating tank. Advantageously, the damper has the shape of a flat or curved plate, preferably oriented perpendicularly or obliquely to the direction of movement, or the shape of an open cavity, preferably in the shape of a hollow hemisphere, preferably oriented with the cavity against the direction of movement. The damper is preferably mounted so that it is out of reach of the turbulent flow created by the floating tank itself, preferably on the side of the floating tank. Advantageously, the floating tank is equipped with at least one damper for each kinematic degree of freedom, preferably multiple dampers. Advantageously, the floating tank has shock absorbers located symmetrically to at least one axis of movement. The damper is preferably extendable and/or tiltable and/or removable and/or remotely controlled. For example, a floating tank that has two degrees of freedom, i.e. it can swing vertically and swing sideways, tilt in one vertical plane, should be equipped with two shock absorbers, i.e. for swinging and for side swinging. The damper can dampen the rocking or swaying of the floating tank by up to 90%.

Advantageously, the pumped storage power plant can be equipped with another, auxiliary energy system, with the help of which the submergence of the floating tank can preferably be gently regulated and/or its swaying on the liquid level in the base tank can be dampened when the operation of the main power system is stopped and, for example, to facilitate loading and unloading of transported material or when people get on and off.

Since the floating tank in general can be extendable high above the surrounding terrain, a solar and/or wind power plant can advantageously be placed on it, the electrical energy of which can advantageously be directly accumulated in the floating tank. An interesting advantage here is that the average power output of both the solar and wind power plants increases with greater displacement of the floating tank - offering more sunshine and faster wind.

The surface and internal, i.e. gas, spaces of the floating tank can be advantageously used for other purposes, for example for housing, for sports and recreational activities, such as a lookout tower or for advertising purposes.

During the periodic transformation of electrical energy into potential energy, and vice versa, losses in the energy system will be manifested by heating the water in the tanks, especially when covering or insulating the tanks, which may have a relatively small volume, which results in a lower risk of freezing of the water and the surrounding terrain in winter , regardless of the industrial, agricultural and recreational possibilities of using the accumulated waste heat. Advantageously, this waste heat can be used with the help of heat pumps for heating and/or for further production of electricity.

Even in the raised position, the floating tank is very resistant to earthquakes, and especially with large dimensions it is resistant to adverse weather conditions.

The production of steel, as well as the transport during the construction of the pumped storage power plant according to the invention, are energy-intensive as with other hydropower plants, but due to the similarly long life of the power plant, its overall carbon footprint is also relatively insignificant, especially compared to other types of storage power plants, e.g. electrochemical .

The pumped storage power plant according to the invention is particularly suitable for large outputs and capacities that grow approximately with the fourth power of the dimension.

In vast base reservoirs, e.g. in lakes in the area of mined surface mines or in the sea, a floating reservoir can be conveniently built with a large discharge height and a large diameter.

Compared to existing solutions, the pumped storage power plant according to the invention shows an all-round improvement in parameters and other useful properties:

- makes much better use of the area and depth of the basic tank,

- makes maximum use of the strength properties and corrosion resistance of the structural material,

- 15 CZ 309913 B6

- minimizes the weight of the float,

- multiplies the discharge height of pumping,

- maintains the cohesion and stability of the structure against overturning even in very strong winds,

- the modular design simplifies the production and assembly of the floating tank,

- achieves a much more favorable ratio of the price of the floating tank and the accumulated energy.

When comparing the achievable capacities of accumulated energy, the pumped-storage power plant with a floating tank of a more efficient design according to the invention significantly exceeds the capabilities of existing pumped-storage power plants with a floating tank:

For example, a current pumping station with a lower or upper floating reservoir created in a base reservoir with a depth of 50 m with a usable depth of 40 m can achieve a working lift of N = 20 m and a discharge height of V = 20 m in an optimal design, so it will have a theoretical capacity of approximately E = 1100 MWh/100 ha, while a pumped storage power plant with an upper floating reservoir according to the invention created in the same basic reservoir with a depth of 50 m can achieve a working lift of N = 28 m at an optimal discharge height of V = 500 m at the same usable depth of 40 m, so it will have theoretical capacity significantly higher, i.e. approximately E = 38,100 MWh/100 ha.

For model calculations to compare the energy efficiency of different designs of hydroelectric power plants, it is sufficient to consider only variable physical quantities and instead of total energy values, only their equivalents should be monitored.

For example, the equivalent Ee of the change in potential energy of a floating tank, expressed by the discharge head V and the working lift N, can be simply expressed by multiplying both quantities:

Ee = V.N

The use of pumping stations with a floating tank according to the invention makes it possible to solve the fundamental problems of the electric power industry:

- to multiply the accumulated amount of electrical energy against the current state,

- quickly balance the disproportions between the variable consumption of electricity and the highly irregular production from renewable sources,

- to provide the possibility of compensating the power factor and unevenness in the electrical network by using rotating machines,

- reduce the costs of solving disproportions between the production and consumption of electricity,

- expand and make the production of electricity from renewable sources cheaper,

- limit energy production from fossil fuels,

- increase energy self-sufficiency and security for large and small territorial units,

- to limit the massive transmission of electricity over long distances and between countries, - to significantly contribute to the improvement of the environment.

Clarification of drawings

The invention will be explained in more detail on examples of execution according to the attached drawings:

Fig. 1 shows a diagram of a normal floating tank module, Fig. 2 shows a diagram of a module with an energy system, Fig. 3 shows a diagram of the arrangement of the upper collecting pipe,

- 16 CZ 309913 B6 Fig. 4 shows the swimming scheme of the floating tank module with a one-piece float, Fig. 5 shows the swimming scheme of the floating tank module with a three-piece float, Fig. 6 shows the scheme of the pumping station with the upper floating tank with hydropower equipment, Fig. 7 shows a diagram of a pumped-storage power plant with an upper floating tank with a hydropower system and with different building heights of the modules.

Examples of implementation of the invention

Fig. 1 shows a diagram of a common floating tank module.

A common floating tank module 7.1 has three basic parts:

- the upper part - water tank 7a, is stressed mainly by the internal overpressure of the water,

- middle part - intermediate piece 7b, which serves to support the upper part and to connect the upper and lower parts, is stressed mainly by the vertical weight of the supported parts,

- lower part - float 7c, which serves to support the upper and middle parts and sinks into the base tank 2, thereby creating the buoyancy needed to accumulate potential energy, is stressed mainly by the external overpressure of the water and the vertical weight of the supported parts.

Modules 7.1 are reinforced inside and outside with flat vertical braces to reinforce the walls of modules 7.1 and to connect modules 7.1 to each other.

From the bottom of the water tanks 7a, branches of the water pipe 12 are brought out, which are equipped with regulating water valves 18. These branches are connected to the double upper collection water pipe 12 located in the upper part of the intermediate pieces 7b.

In the lower part of the floats 7c, the lower collection water pipe 12 is installed, which is equipped with branches with suction baskets to evenly distribute the flow of water during its intake and discharge, in order to avoid unwanted swirling of sludge at the bottom of the base tank 2.

The left part of the picture shows the front view of module 7.1, the right part of the picture shows the side view of module 7.1. A floor plan of module 7.1 is shown below the side view, a section of module 7.1 is shown to the right of the side view.

Fig. 2 shows a diagram of a separate module of a floating tank with a hydropower system. This standalone module 8 has some modifications compared to the regular module 7.1 to which it is attached.

A vertical water pipe 12 is installed in the intermediate piece 7b and in the float 7c, which connects the upper and lower horizontal lines of the collecting water pipe 12 and which is connected to the water energy systems 15.

The upper part of the float 7c is extended at the expense of the intermediate piece 7b to accommodate the water power system, which has a two-machine arrangement - a reverse turbine 15a and a motor generator 15b - with a vertical shaft.

The reverse turbine 15a is situated at such a height that its horizontal axis is always below the water level in the base tank, i.e. even in the upper operating position of the floating tank. It thus permanently ensures a negative suction height.

- 17 CZ 309913 B6

The motor generator 15b is located above the reverse turbine 15a above the water level in the base tank 2.

Above and below the reverse turbine 15a, water seals 18 are located in the vertical water pipe 12.

In the elevated part of the float 7c, a lifting device 36 is installed to facilitate assembly work on the hydropower system 15.

Fig. 3 shows a diagram of the arrangement of the upper collection pipe in the upper part of the intermediate piece under the water tank. The diagram shows the arrangement of the modules in triangular formations, which ensure an optimal solution for the strength of the module system when loaded with horizontal stress. The collecting water pipe 12 is made up of two layers of pipelines connected to each other. The location of the water pipe 12 in the cross-section of the intermediate piece 7b is chosen so that the walls of the intermediate piece 7b and the vertical reinforcements are weakened as little as possible. The criss-cross arrangement of the pipe runs ensures that the same number of water tanks are connected to each hydropower system, which helps their even filling/draining and the stability of the floating tank on the water level of the base tank. The vertical interconnection of horizontal pipelines serves to ensure a sufficient and even supply of water to hydropower systems and an even distribution of water when operating a different number of hydropower systems.

Giant. 4 shows a floating tank module float diagram with a one-piece float. The module 7.1 contains a water tank 7a, an intermediate piece 7b and a one-piece float 7a, which are made of thin sheet metal and have a circular horizontal cross-section. Intermediate piece 7b has a wall thickness _.

In Fig. 4a, the module 7.1 is in the upper operating position with an empty water tank 7a, in Fig. 4b the module 7.1 is in the lower operating position with a full water tank 7a. The water height N in the water tank is equal to the operating lift N, i.e. the height difference between the upper and lower operating positions of the module 7.1. The height difference V between the water level 11 in the water tank 7a (upper tank) and the water level 11 in the base tank 2 (lower tank) therefore remains the same in both operating positions of the module 7.1.

Giant. 5 shows a floating tank module floating diagram with a three-piece float. Module 7.1 contains a water tank 7a, an intermediate piece 7b and a three-piece float. The float 7c contains sections 7c1, 7c2, 7c3 (segments) which are made of a thin sheet of thickness t and their horizontal cross-section has a circular shape.

The individual sections 7c1, 7c2, 7c3 of the float 7c are filled with air with an overpressure equal to the largest hydrostatic water pressure to which the given section 7c1, 7c2, 7c3 of the float 7c is exposed when fully immersed in the base tank 2, i.e. the sections 7c1, 7c2, 7c3 of the float 7c located deeper are filled with air of greater overpressure.

The upper bottom of the lower section 7c1 serves as a pressure partition between the lower section 7c1 and the middle section 7c2, the upper bottom of the middle section 7c2 serves as a pressure partition between the middle section 7c2 and the upper section 7c3.

Thus, this three-piece float 7c can have thinner walls and therefore less weight than a one-piece float of the same height, i.e. with the same buoyancy. The spacer 7b and/or the water tank 7a can therefore be higher than in the one-piece float module 7.1.

In Fig. 5a, module 7.1 is in the upper operating position, in Fig. 5b, module 7.1 is in the lower operating position. The water height N in the water tank 7a is equal to the operating lift N, i.e. the height difference between the upper and lower operating positions of the module 7.1. The height difference V between the water level 11 in the water tank 7a (upper tank) and the water level 11 in the base tank 2 (lower tank) therefore remains the same in both operating positions of the module 7.1.

- 18 CZ 309913 B6

Fig. 6 shows a diagram of a pumped-storage power plant with an upper floating tank with a hydropower system. Fig. 6a and 6b show an elevation of the pumped storage power plant, Fig. 6c shows its floor plan.

The floating tank 7 is located in the basic tank 2 and is assembled from a set of modules 7.1 of pressure vessels with a circular cross-section, which are connected to each other by flat reinforcements in triangular formations. The common module 7.1 of the floating tank 7 has three basic parts: - upper part - water tank 7a, - middle part - intermediate piece 7b, - lower part - float 7c.

The width to height ratio of the floating tank 7 is approximately 1.5 to ensure its stability against overturning.

The floating tank 7 is stabilized against horizontal movement in the basic tank 2 by a guide frame 14, which has a floating part 14a and an anchor part 14b, which are hinged together. The anchor part 14b is also hinged in the foundations on the bank 1 of the base tank 2.

By consuming electrical energy equivalent to Ee = -V*N from the network, the potential energy of water is accumulated by pumping it from the base tank 2 through the water pipe using water power systems to the water tanks 7a. The floating tank 7 descends, while its floats 7c sink into the base tank 2. Fig. 6a shows the floating tank 7 in the lower operating position.

By discharging water from the water tanks 7a through the water pipe through the water power systems into the base tank 2, with the consumption of the water's potential energy, it produces electrical energy equivalent to Ee = V*N and is supplied to the network. The floating tank 7 rises, while its floats 7c emerge from the base tank 2. In Fig. 6b, the floating tank 7 is shown in the upper operating position.

If the outer horizontal cross-section of the floats 7c is equal to the inner horizontal cross-section of the water tank 7a, then when water is pumped between the base tank 2 and the floating tank 7, the water level 10 in the base tank 2 does not change, nor does the height difference V between the water level 11 in the floating tank 7 and the water level 10 in the base tank 2 in the upper or lower operating position.

Fig. 7 shows a diagram of a pumped storage power plant with an upper floating tank with a hydropower system. The floating tank 7 is located in the basic tank 2 and is assembled from a set of modules 7.1, 8 with different construction heights.

Common 7.1 modules are equipped with:

- floats 7c with different immersion depths according to the depth profile of the basic tank 2, - intermediate pieces 7b with a correspondingly different height and

- water tanks 7a, which have the same height for all common modules 7.1, because the floating tank 7 moves as a whole during pumping and has a uniform operating stroke for all common modules 7.1.

For each group of common modules 7.1 with the same construction height, there is a corresponding group of energy systems 15 and collection water pipes 12 with the same discharge height.

Energy systems 15 are located in separate modules 8, which are attached to floats 7c of regular modules 7.1.

The filling and emptying of all water tanks 7a can be carried out simultaneously and proportionally in order to minimize the shear stress in the stiffeners especially between the common modules 7.1 with different building heights.

- 19 CZ 309913 B6

Fig. 7a shows the floating tank 7 with empty water tanks 7a in the upper operating position. Fig. 7b shows the floating tank 7 with filled water tanks 7a in the lower operating position.

The floating tank 7 uses almost the entire width and depth, i.e. almost the entire volume, of the base tank 2.

Industrial applicability

The pumping station according to the invention has prerequisites for extensive use:

- the power plant is fundamentally and functionally simple, which are important conditions for its reliability, - the overpressure of the fluid in the power system can be almost constant throughout the working stroke, - the power plant has very good energy efficiency when pumping liquid,

- the power plant can be started and stopped with high alertness,

- power plants can be built directly in locations with uneven production or consumption of electricity,

- the power plant can be built with output and capacity optimally according to local conditions,

- the power plant can be created in a wide range of variants for different geographical and urban conditions and for wider purposes of use,

- for the construction of the power plant, land after industrial areas or raw material extraction, flooded areas and other suitable locations can be used,

- the power plant enables long-term energy storage without loss of capacity,

- there are interesting possibilities of using waste heat from energy systems,

- the floating tank of the power plant can be produced using common, cheap and ecological materials such as steel, with a long service life of tens to hundreds of thousands of cycles, tens to hundreds of years,

- during the development and construction of the power plant, it is possible to build on experience with the construction of energy water works,

- the power plant, especially its floating tank, is very resistant to earthquakes and adverse weather conditions,

- if the base tank of the power plant is buried in the ground, there is no risk of flooding the surroundings with water in the event of damage to the base or floating tank,

- the basic tank can also serve as a water reservoir for emergency situations,

- the operation of the power plant is ecological, it does not produce harmful waste,

- the power plant material is fully recyclable,

- the power plant has low operating costs,

- the economy of investment and operation is comparable to a classic pumped-storage power plant with two ground tanks.

Claims (10)

PATENT CLAIMS 1. A pumped storage power plant that includes a floating tank (7) located in a base tank (2) in an environment of two fluids with different densities, while there is a height difference between the operating levels (10, 11) of the denser fluid in the tanks (2, 7, 7a) (V), where the base tank (2) is the lower tank and the floating tank (7) is the upper tank, further the floating tank (7) contains a float and a tank (7a) for a denser liquid, the float (7c) being arranged to create buoyancy for carrying the floating tank (7) in the base tank (2), and the power plant further includes a pipe (12) and an energy system (15) for pumping fluid between the lower tank and the upper tank, characterized in that the floating tank (7) contains an intermediate piece ( 7b), with the bottom-shifting arrangement, consists of: a float (7c), an intermediate piece (7b) and a tank (7a) for a denser liquid, while the intermediate piece (7b) is arranged to carry a tank (7a) for a denser liquid. 2. A pumped storage power plant according to claim 1, characterized in that the floating tank (7) is formed by a set of mutually connected modules (7.1, 8), each of which contains a float (7c), an intermediate piece (7b) and a tank (7a) for a denser liquid . 3. A pumping power plant according to claim 1 or 2, characterized in that the outer horizontal cross-section of the floats (7c) is equal to the inner horizontal cross-section of the tank (7a) for the denser liquid in order to maintain a constant height level of the surface (10) of the denser liquid in the base tank (2) and constant height levels of the surface (11) of the denser liquid in the floating tank (7). 4. A pumped storage power plant according to claims 1 to 3, characterized in that the float (7c) is filled with gas whose internal excess pressure is equal to or greater than the external excess pressure of a denser liquid corresponding to the largest immersion depth of the float (7c) in the base tank (2). 5. A pumped-storage power plant according to claims 1 to 4, characterized in that the float (7c) is divided in height into several sections (7c1, 7c2, 7c3), which are separated from each other by a pressure partition, while each section (7c1, 7c2, 7c3) is filled with gas whose internal excess pressure in each compartment (7c1, 7c2, 7c3) is equal to or greater than the external excess pressure of the denser liquid corresponding to the greatest immersion depth of the respective compartment (7c1, 7c2, 7c3) in the base tank (2). 6. A pumped storage power plant according to claims 1 to 5, characterized in that the modules (7.1, 8) are designed with different immersion depths according to the depth profile of the base tank (2). 7. Pumped storage power plant according to claims 1 to 6, characterized in that it contains a guide frame (14) for securing the floating tank (7) against horizontal movement in the base tank (2). 8. A pumped storage power plant according to claims 1 to 7, characterized in that the floating tank (7) is formed with a continuous bottom. 9. Pumped storage power plant according to claims 1 to 8, characterized in that the pipe (12) is located inside and/or outside the floating tank (7). 10. Pumped storage power plant according to claims 1 to 9, characterized in that the power system (15) is located inside or outside the floating tank (7).