Liquid reservoir

Abstract

The present invention relates to a liquid reservoir (100) for storing a liquid, in particular water, which liquid reservoir comprises at least one flexible bag (1). The at least one flexible bag (1) is designed to be completely submerged in the water of a body of water (200) and / or in a fluid of a fluid reservoir (300), in particular in the water of a water reservoir.

Description

[0001] Liquid storage

[0002] Description

[0003] The invention relates to a liquid reservoir for storing a liquid, in particular water. Furthermore, the invention relates to the use of such a liquid reservoir for storing a liquid beneath the water of a body of water or beneath the fluid of a fluid reservoir.

[0004] It is an object of the invention to provide a liquid reservoir for storing a liquid, in particular water, which is of simple construction and can be used in many applications.

[0005] This problem is solved by the features of the independent claim. The dependent claims relate to preferred embodiments of the invention.

[0006] A liquid reservoir for storing a liquid, in particular water, comprises at least one flexible bag. The at least one flexible bag is designed to be arranged completely underwater in a body of water and / or a fluid in a fluid reservoir, in particular underwater in a water reservoir. The at least one flexible bag advantageously forms the fluid-absorbing volume of the liquid reservoir. The liquid reservoir can, in particular, have only one flexible bag. However, it is also possible for the liquid reservoir to be composed of several flexible bags. The several flexible bags are connected to one another in a fluid-conducting manner, so that the bags form a total volume of the liquid reservoir. In the following, the invention is mostly described using a liquid reservoir with only one flexible bag.However, it is always intended that the liquid reservoir forms its volume through the combination of several flexible bags. If the liquid reservoir has only one flexible bag, the formulation that the liquid reservoir is designed as a flexible bag can be used. The benefit of the flexible bag in the liquid reservoir for storing a liquid lies, among other things, in the fact that it adapts its volume 100% to the fill level of the liquid. The number of cubic meters of space the liquid reservoir takes up in the surrounding medium, i.e. in the fluid of the fluid reservoir or in the water of the body of water, corresponds to the number of cubic meters of liquid the liquid reservoir contains. The liquid reservoir therefore does not “waste” any space when empty.

[0007] For the purposes of the invention, the body of water is preferably the sea, i.e. salt water, or a lake. However, use in a river, particularly a correspondingly large one, or a pond is also possible. The fluid reservoir for storing a fluid is a liquid reservoir for storing a liquid, preferably water. However, the term "fluid reservoir" is used to distinguish it from the liquid reservoir with the at least one flexible bag. For the purposes of the invention, however, the previously described liquid reservoir with the at least one flexible bag can also be referred to as the first liquid reservoir and the fluid reservoir as the second liquid reservoir.Unless otherwise stated below, in the present invention, the term liquid reservoir always refers to the liquid reservoir with the at least one flexible bag, wherein the fluid reservoir is the reservoir in which the liquid reservoir with the at least one flexible bag can be arranged / is arranged.

[0008] The fluid reservoir is, in particular, an open fluid reservoir, i.e., a fluid reservoir with an open side in which the liquid is in contact with the ambient air. The fluid reservoir can, for example, be an artificial reservoir or a basin, which is located or built, in particular, on and / or in the ground. For example, the fluid reservoir can be a basin in a water treatment plant.

[0009] For the sake of completeness, it should be mentioned that the liquid storage device preferably does not require any connection to the atmosphere and does not need to be placed under vacuum. Because the bag is flexible, its volume can easily be changed.

[0010] The liquid reservoir or the at least one flexible bag is preferably made from a plurality of film pieces, in particular plastic film pieces, which are connected to one another. The plastic bag is particularly suitable for use underwater. The plastic film pieces are preferably welded together to form the flexible bag. The plastic film pieces each preferably have at least one layer of HDPE. In particular, the plastic film pieces can be made (completely) from HDPE. HDPE here refers to the plastic material hard polyethylene (English: high-density polyethylene). Hard polyethylene is stable, tear-resistant, heat-resistant, and resistant to water and acids, among other things. Therefore, a flexible bag made from plastic film pieces with at least one layer of HDPE, in particular made completely from HDPE, is suitable for use in salt water.

[0011] According to a preferred embodiment, the at least one flexible bag comprises a cover film, a base film, and a central region having a plurality of plastic film rings. The film rings are welded to one another in such a way that the central region is designed in the shape of a bellows. The cover film and the base film are welded to the central region, thus forming a storage space for storing a liquid, in particular water. This construction of the flexible bag avoids stress fields when the flexible bag is folded in and out during emptying or filling. The proposed flexible bag with the central region designed as a bellows further offers the advantage that it can be filled and emptied without the cover film and the base film expanding or shrinking, or attempting to wrinkle. The flexible bag can thus be manufactured to be robust and durable.

[0012] Within the scope of the invention, a bellows-shaped region is, in particular, a region with at least partially, in particular completely, circumferential outer folds and inner folds that are formed alternately in the vertical direction of the liquid reservoir or the flexible bag, wherein the volume of the flexible bag or its storage space can be changed by folding them in and out. "At least partially, in particular completely, circumferential" here means, in particular, that the outer folds and inner folds extend at least partially, in particular completely, in the circumferential direction of the flexible bag.

[0013] It should be understood that the middle area is the area between the cover film and the bottom film in the height direction of the liquid storage or the flexible bag.

[0014] The height direction of the liquid storage or the flexible bag is in particular a direction perpendicular to the cover film and / or base film.

[0015] It should be noted that the bellows is not an accordion-like design. In other words, the flexible bag, with its bellows-shaped central region and its ability to change its volume without any folding of the surfaces of the cover and base films, does not replicate the principle of an accordion. The folding of a bellows is not the same as the folding in an accordion. In other words, a bellows is not an accordion. An accordion does not have the drape of folds like in the proposed liquid storage device. A completely different principle applies here. Firstly, the accordion does not consist of wave-like folds, but of creases; creases that bend out and then bend back in again. Furthermore, the folding of an accordion is a reciprocal double fold, with each "positive" fold having a corresponding "negative" fold at a 90° angle.In the context of the present invention, the term “film ring” can be understood in particular as a film strip that extends in the circumferential direction of the sack and at least partially, in particular completely, encloses / surrounds an opening or defines an open or closed recess. This means that the film strip extends at least partially, in particular completely, in the circumferential direction or is at least partially, in particular completely, circumferentially. This means that the term “film ring” does not require a circular outer contour. For example, the film ring can have an oval-shaped outer contour. To produce a film ring, for example, a film can be used in which the opening is created by cutting out the corresponding material. The film ring can be considered a single piece of film.However, it is also possible for a foil ring to be formed from a plurality of foil pieces arranged in the circumferential direction and connected to one another, in particular welded.

[0016] The cover film can advantageously be formed as a single piece of film or from a plurality of interconnected, in particular welded, film pieces. Accordingly, the base film can advantageously be formed as a single piece of film or from a plurality of interconnected, in particular welded, film pieces.

[0017] The cover film and the base film are advantageously designed identically.

[0018] The foil rings are advantageously designed identically.

[0019] The central region can advantageously have an even or odd number of foil rings. The central region preferably has at least two foil rings.

[0020] Each foil ring is advantageously welded at its outer edge region and at its inner edge region. Preferably, the central region can be designed such that the foil ring adjacent to the cover foil is welded at its outer edge region to the cover foil and at its inner edge region to its adjacent foil ring, and the foil ring adjacent to the bottom foil is welded at its outer edge region to the bottom foil and at its inner edge region to its adjacent foil ring. Each of the remaining foil rings, i.e., each foil ring adjacent only to foil rings, is welded at its outer edge region to an adjacent foil ring and at its inner edge region to another adjacent foil ring.When the bag is completely filled with liquid, the angle between adjacent film rings and / or the angle between a film ring in the central region and the cover film welded to this film ring and / or the angle between another film ring in the central region and the bottom film welded to this other film ring is / are a maximum of 20 degrees, preferably a maximum of 10 degrees, and furthermore preferably a maximum of 5 degrees. Thus, the bending of the film rings when the bag is full can be kept within a range that has a positive influence on the welds of the film rings and thus the longevity of the liquid storage device.

[0021] Preferably, a width of each film ring is between 0.3 m and 2.2 m, preferably between 0.7 and 1.8 m, particularly preferably between 1 m and 1.5 m.

[0022] Preferably, a ratio of the width of each foil ring to a length of an opening enclosing an inner edge of the corresponding foil ring is between 0.02 and 0.2, preferably between 0.04 and 0.06.

[0023] Preferably, a ratio of the width of each foil ring to a width of the opening enclosed by the inner edge of the corresponding foil ring is between 0.03 and 0.06, preferably between 0.04 and 0.05.

[0024] With these dimensions, it has been shown that bending of the film rings when the bag is full can be kept to a minimum. Furthermore, the largest possible storage space can be achieved without compromising the strength of the liquid storage unit.

[0025] For the purposes of the present invention, a fully filled / full bag is one in which the stored liquid quantity corresponds to a maximum permissible liquid quantity. The maximum permissible liquid quantity is advantageously the liquid quantity with which at least 10,000, particularly preferably at least 30,000, complete filling cycles of the bag can take place.

[0026] The cover film and the bottom film can advantageously be arranged parallel to one another, particularly when the bag is completely filled with liquid. However, it is also possible for the cover film and the bottom film to be inclined rather than parallel to one another, particularly when the bag is completely filled with liquid. This can be particularly advantageous if the bag is arranged on an inclined floor or floor region of a fluid reservoir or a body of water, for example on a seabed that slopes down to the open sea. The bottom film of the liquid reservoir lies on the inclined floor or floor region, with the cover film being parallel to the fluid surface of the fluid reservoir or to the water surface of the body of water when the liquid reservoir is, in particular, completely full. The bottom film lies parallel to the floor of the fluid reservoir or the body of water.The bottom liner adapts to the bottom of the fluid reservoir or body of water, resulting in an inclination between the cover liner and the bottom liner. One side, in particular, is higher than the other.

[0027] In order to achieve the inclined position between the cover film and the base film, the film rings can, according to an advantageous embodiment, only extend partially in the circumferential direction. This means that the film rings are open (not closed). In this case, the outer folds and the inner folds are only partially circumferential. The cover film and the base film are (directly) welded to one another or welded to one another in the area in which the film rings do not extend. For example, in the case of a flexible sack, the outer folds and inner folds can only be formed in the circumferential direction on three sides of the sack, with the cover film being welded directly to the base film on the fourth side. In this case, the sack can only unfold on the "thicker / taller" side, with the height of the outer folds (automatically) tapering from a maximum height (e.g. 20 cm on the "thicker" side) to a height of 0 cm on the narrower side.

[0028] It is also possible for a plurality of film rings to extend completely in the circumferential direction, with the remaining film rings extending only partially in the circumferential direction. Such a bag advantageously has a uniform fold height in the area of ​​the majority of film rings, while the bag cannot unfold in the area of ​​the remaining film rings.

[0029] Advantageously, both the cover film and the bottom film are wrinkle-free, especially when the bag is completely filled with liquid. This also applies in particular to any filling state (empty state and any filled state) of the liquid reservoir.

[0030] Preferably, a cross-section, in particular each cross-section, of the liquid reservoir or of the flexible sack has an outer contour without corners perpendicular to the height direction. In particular, the outer contour of the cross-section has the shape of a rounded rectangle. Other shapes, such as a circle or an oval, are also possible. In the previously described advantageous embodiment of the liquid reservoir with the flexible sack, which has the cover film, the base film, and the film rings, the cover film and / or the base film and / or the film rings preferably each have an outer contour without corners, in particular in the shape of a rounded rectangle. Other shapes, such as a circle or oval, are also possible for the outer contour. In this case, the outer contour of the cover film corresponds to the outer contour of each cross-section of the cover film perpendicular to the height direction.The same applies to the base film and the film rings. The absence of corners allows stress zones to be avoided, resulting in improved robustness of the liquid reservoir. The cover film and / or the base film are advantageously plastic films. The cover film and / or the base film each preferably has at least one layer of HDPE. In particular, the cover film and / or the base film can preferably be plastic films (completely) made of HDPE.

[0031] Preferably, the height distance between adjacent outer folds of the bag is a maximum of 0.40 m, preferably a maximum of 0.25 m when the bag is completely filled with liquid. Preferably, the height distance between adjacent outer folds of the bag is in a ratio to the height of the liquid reservoir of a maximum of 1 to 8, preferably a maximum of 1 to 10, preferably a maximum of 1 to 20, preferably a maximum of 1 to 40, when the bag is completely filled with liquid. This prevents excessive or excessive bending of the film rings, particularly with a given width of the film rings.

[0032] The liquid reservoir preferably further comprises a distance limiting device. The distance limiting device can be designed such that, when the bag is filled with liquid, in particular when the bag is completely filled with liquid, the height between adjacent outer folds of the bag is less than or equal to a predetermined distance. This makes it possible to limit the unfolding of the flexible bag per outer fold, e.g., to 25 cm per outer fold. This prevents the film rings from bending too far when the bag is filled with liquid, which could lead to damage to the flexible bag at the weld points between the film rings, the cover film, and the base film. The distance limiting device can also be referred to as an unfolding limiting device. The height between adjacent outer folds can in particular also be understood as the unfolding width.

[0033] The distance limiting device can advantageously be designed such that the previously described inclined position between the cover film and the base film can be realized. To this end, the height distance between adjacent outer folds in one area of ​​the bag can be selected to be greater than the height distance between adjacent outer folds in another area of ​​the bag, so that the bag unfolds more on one side (the desired "thicker" side) than on the other side (the desired "narrower" side). For example, if the height limit of the outer folds on the thicker side of the bag allows a height of 20 cm each, but the height limit on the desired narrower side allows a maximum of 5 cm of unfolding, the bag, when fully unfolded, will be four times as thick on the thicker side as on the opposite side.

[0034] The liquid reservoir preferably has a plurality of connecting pieces and a plurality of connecting elements. At least one of the connecting pieces is arranged, preferably welded, on each outer fold of the bag. In particular, at least one of the connecting pieces is arranged, preferably welded, on each outer fold of the bag. The connecting pieces between adjacent outer folds are connected to one another by means of one of the connecting elements. This means that at least one connecting piece on an outer fold and at least one connecting piece on an adjacent outer fold are connected to one another by means of a connecting element. The provision of the connecting pieces and the connecting elements ensures that the flexible bag unfolds as evenly as possible during the filling process, whereby the stress on the flexible bag is also as even as possible.

[0035] In particular, the connecting pieces and connecting elements can be parts of the distance limiting device. In other words, the distance limiting device can comprise the connecting pieces and connecting elements. In this case, the connecting pieces and connecting elements can be designed such that when the bag is filled with liquid, in particular when the bag is completely filled with liquid, a height distance between adjacent outer folds of the bag is less than or equal to the predetermined distance. In this case, the connecting pieces can be designed as distance limiting pieces or unfolding limiting pieces, and the connecting elements can be designed as distance limiting elements or

[0036] These are referred to as unfolding limiting elements. If the distance limiting device is designed to achieve the inclined position between the cover film and the base film, the connecting elements and / or the connecting pieces are designed accordingly. The predetermined distance preferably corresponds to a permissible maximum distance.

[0037] Preferably, a plurality of connecting pieces are arranged on at least one outer fold, particularly preferably on each outer fold, in the circumferential direction of the bag, in particular at predetermined intervals. Preferably, the connecting pieces are evenly distributed in the circumferential direction on at least one outer fold, in particular on each outer fold. For example, the limitation of the unfolding height of the individual outer fold can be implemented circumferentially around the entire flexible bag at predetermined intervals of five meters from each other.

[0038] One of the connecting pieces, preferably each connecting piece, can be designed in particular as a tab. One of the connecting elements, preferably each connecting element, can be designed in particular as a cable.

[0039] Preferably, the flexible bag has a storage capacity of at least 100 m 3 , further preferably of at least 500 m 3 , further preferably of at least 1000 m 3 , further preferably of at least 5000 m 3 The storage capacity corresponds in particular to the maximum storage capacity when the flexible bag is full. For example, the flexible bag can have a storage capacity of 50,000 m 3As already described above, the liquid reservoir can comprise a plurality of flexible bags connected to one another in a fluid-conducting manner, which then advantageously form the total fluid-absorbing volume of the liquid reservoir. For example, it is possible for the liquid reservoir to consist of ten flexible bags, each with a storage capacity of 50,000 m 3 (total storage capacity of the liquid reservoir: 500000 m 3 ).

[0040] Preferably, the liquid reservoir can have an access opening and a closure device for closing and releasing the access opening. An interior of the flexible bag is accessible via the access opening, in particular for a cleaning robot or another device, for example an inspection device. Thus, the bag can be easily cleaned or the interior can be inspected. The access opening is formed in the flexible bag. In other words, the flexible bag has the access opening. The access opening preferably has an area of ​​at least 400 cm 2 , particularly preferably at least 900 cm 2The access opening can preferably be formed in the cover film. The closure device can, in particular, be designed as an access hatch. For example, a vacuum robot can be inserted into the flexible bag through this opening when the opening is open to clean the bottom of the bag of sludge sediment or contaminants that may accumulate in the bag over time.

[0041] Preferably, the liquid reservoir further comprises at least one valve configured to release air contained in the flexible bag. In particular, the valve is configured to open automatically to remove the air contained in the flexible bag. This allows any air that may be pumped into the flexible bag to escape automatically.

[0042] Alternatively or additionally, the valve can be designed to release fluid contained in the flexible bag when a predetermined (permissible) pressure value in the storage chamber is exceeded. This ensures that the fluid reservoir is always at the permissible pressure.

[0043] The valve can thus advantageously function simultaneously as an air outlet valve and “overflow”, so that in the event that the fluid pressure in the flexible bag increases above the permissible pressure, the excess fluid pumped in can be released.

[0044] It should be noted that an opening in the valve through which air and / or liquid can be removed cannot be understood as an access opening. Preferably, the liquid reservoir may comprise a fixing weight receiving device for receiving a fixing weight for fixing the liquid reservoir to a bottom of the body of water and / or the fluid reservoir. In addition or alternatively to the fixing weight receiving device, the liquid reservoir may preferably comprise an anchoring device for anchoring the liquid reservoir to a bottom of the body of water and / or the fluid reservoir. These devices are particularly advantageous when the liquid reservoir is arranged in a sea or a river due to the water flow.Securing the liquid storage device to the bottom of a fluid reservoir or body of water is also particularly advantageous if the flexible bag is made of a material that is lighter than the fluid in the storage device or lighter than water, as otherwise the liquid storage device would not remain at the bottom of the fluid reservoir or body of water but would float. For example, HDPE and most other plastic films are lighter than water.

[0045] The fixing weight receiving device and the anchoring device can advantageously also be designed as a single device.

[0046] The fixing weight receiving device and / or the anchoring device can, for example, comprise tabs that are attached, in particular welded, to the flexible bag. The tabs can be weighted down with a heavy load, referred to as a fixing weight, and / or, if anchoring points are present in the fluid reservoir or body of water, can be attached to the anchoring points.

[0047] Furthermore, the present invention relates to a first system comprising a fluid reservoir for storing fluid, a previously described liquid reservoir, a turbine, and an electric machine. The fluid reservoir is, as already described, in particular a liquid reservoir for storing a liquid, preferably water, wherein the previously described liquid reservoir can be referred to as the first liquid reservoir and the fluid reservoir as the second liquid reservoir. Preferably, the fluid reservoir is designed as a reservoir, in particular an artificial reservoir. The reservoir is designed in particular as an upper reservoir. The reservoir can in particular be located on a cliff or a high plateau.The turbine is fluidically connected to the fluid reservoir, wherein the fluid reservoir is fluidically connected to the turbine in a closed system, such that the fluid from the fluid reservoir can be conducted through the turbine to drive the turbine and can be absorbed by the flexible bag of the fluid reservoir. The electric machine is driven by the turbine to generate electrical current. This means that the electric machine is designed or operable as a generator for this purpose. The fluid reservoir is lower than the fluid reservoir and completely submerged in a body of water (in particular not in the fluid reservoir). Preferably, the fluid reservoir is located in the sea. It should be noted that the fluid reservoir, the previously described fluid reservoir, the turbine, and the electric machine are to be understood in particular as parts of an energy storage device.In other words, within the scope of the arrangement, the system can be regarded in particular as having an energy storage device, wherein the energy storage device comprises the fluid storage device, the liquid storage device, the turbine and the electric machine.

[0048] The term “underwater a body of water” in the context of the invention means that the liquid reservoir is located below the water surface of the body of water; in particular, the liquid reservoir is in contact with the surrounding water. In particular, it is intended that the liquid reservoir is completely underwater at any fill level, even when the liquid reservoir is fully filled. In particular, the liquid reservoir stands or lies on the bottom of the body of water. By using the flexible bag, it is not absolutely necessary to provide a foundation on the bottom of the body of water, since the contours of the flexible bag adapt to the corresponding surface. The body of water is preferably the sea, i.e. salt water, or a lake. However, use in a sufficiently large river is also possible.

[0049] Preferably, the first system is provided with a turbine operable to pump the fluid from the liquid reservoir into the fluid reservoir. This means that the turbine is preferably designed / configured such that it can be operated as a pump. Preferably, the turbine can be operated to pump the fluid from the liquid reservoir into the fluid reservoir using the electric machine as an electric motor to drive the turbine.

[0050] Alternatively or in addition to using the turbine to pump the fluid from the liquid reservoir into the fluid reservoir, the system can preferably be provided with a pump for pumping the fluid from the liquid reservoir into the fluid reservoir. The pump can be driven, in particular, by the electric machine or another electric machine.

[0051] A second system can also be used to generate electrical power. The second system, like the previously described first system, comprises a fluid reservoir for storing fluid, a previously described liquid reservoir, a turbine, and an electric machine. As already described, the fluid reservoir is in particular a liquid reservoir for storing a liquid, preferably water. The fluid reservoir is preferably designed as a reservoir, in particular an artificial reservoir. The reservoir is in particular designed as an upper reservoir. The reservoir can in particular be located on a cliff or a high plateau. The turbine is fluidically connected to a body of water, in particular the sea.The fluid reservoir is fluidically connected to the turbine in a closed system so that water stored in the fluid reservoir from the body of water, particularly seawater from the ocean, can be conducted through the turbine to drive the turbine. The electric machine is driven by the turbine to generate electrical current. This means that the electric machine is designed or operable as a generator for this purpose. The fluid reservoir is higher than the body of water and completely submerged in the fluid of the fluid reservoir. By using the fluid reservoir and arranging it beneath the fluid of the fluid reservoir, water from the body of water, particularly seawater, can be prevented from entering the groundwater.

[0052] The term "below the fluid of a fluid reservoir" means, in the context of the invention, that the fluid reservoir is located below the fluid surface of the fluid reservoir; in particular, the fluid reservoir is in contact with the surrounding fluid. In particular, it is provided that the fluid reservoir is completely submerged in the fluid reservoir at any fill level, even when the fluid reservoir is fully filled. In particular, the fluid reservoir stands or rests on the floor of the fluid reservoir. The fluid reservoir is preferably an artificial reservoir or a basin, as already mentioned.

[0053] In the second system, the turbine can preferably be used to fill the liquid reservoir. By means of the turbine, water can be pumped (directly) from the body of water into the liquid reservoir. With this system configuration, water from the body of water is constantly moved back and forth by the turbine. Thus, no liquid reservoir is required in the body of water. For this purpose, the turbine is preferably designed so that it can be operated both as a turbine and as a pump. Particularly preferably, the existing electrical machine is used to drive the pump, which is operated as a generator when electrical current is generated. However, it can also be provided that the turbine is drive-connected to two electrical machines, so that one electrical machine can be used as a generator due to its design and the other electrical machine can be used as an electric motor due to its design.In addition or alternatively to using the turbine to fill the liquid reservoir in the fluid reservoir, an (additional) pump can be used advantageously.

[0054] In particular, the second system is provided for the water to be conducted from the liquid reservoir through the turbine into the body of water to generate the electrical current, and for the water to be pumped from the body of water into the liquid reservoir by means of the turbine and / or the additional pump to fill the liquid reservoir.

[0055] Both the first system and the second system can further comprise a photovoltaic system (solar system) connected to the turbine to supply power to the turbine and / or to the additional pump to supply power to the additional pump. In particular, it is provided that the photovoltaic system generates electricity, which can be stored in the energy storage unit formed by the fluid reservoir, the liquid reservoir, the turbine, and the electric machine.

[0056] According to an advantageous embodiment, the first system is provided with a photovoltaic system arranged on the water surface of the body of water, preferably floating. In particular, the photovoltaic system can have corresponding floating bodies to which the modules of the photovoltaic system are attached. In particular, the photovoltaic system can be positioned vertically above the liquid reservoir. The liquid reservoir is thus arranged, in particular completely, beneath the photovoltaic system. The photovoltaic system is preferably anchored to the bottom of the body of water.

[0057] The placement of the liquid storage tank underwater in the first system has the particular advantage of not "using up" any land area. Furthermore, visual impairments are avoided. Another major advantage is that the liquid storage tank underwater is not exposed to sunlight, or only to a limited extent. This allows the use of plastics, especially for the bag, where aging due to solar radiation is an important consideration.

[0058] The positioning of the photovoltaic system above the liquid reservoir in the first system has the advantage of further reducing solar radiation on the liquid reservoir. Furthermore, it prevents watercraft from entering the area of ​​the liquid reservoir. In other words, shipping traffic over the liquid reservoir is avoided, which could otherwise cause significant damage to the liquid reservoir, for example, due to a fishing boat's anchor being thrown up. However, it is possible for the photovoltaic system to be located on land.

[0059] Furthermore, it is preferably provided that the first system comprises a seawater desalination plant. This seawater desalination plant is preferably connected to the turbine and / or the photovoltaic system for its power supply. This allows both the electricity generated directly by the photovoltaic system and the electricity generated in the energy storage device to be used to operate the seawater desalination plant. According to an advantageous embodiment, the seawater desalination plant can be located on the water surface of the body of water. The seawater desalination plant is preferably designed to be floating.

[0060] In particular, the seawater desalination plant is located directly next to the photovoltaic system.

[0061] A pipeline for the produced drinking water preferably leads from the seawater desalination plant to land. Otherwise, the seawater desalination plant does not require any complex connections, as it can draw water directly from the body of water and discharge it back into the water. In a particularly preferred design, the seawater desalination plant does not even require a power connection to land, as the energy storage system and photovoltaic system can be dimensioned so that the generated electricity or stored energy is sufficient to supply the seawater desalination plant.

[0062] According to an alternative advantageous embodiment, the seawater desalination plant can be located on land.

[0063] For example, the following system is possible:

[0064] The photovoltaic system is located on land, specifically at the upper level of a steep cliff, where the sea begins behind a narrow strip of sand. On the upper plateau, a fluid storage facility designed as an artificial pumped-storage lake can be created directly next to the photovoltaic system. However, 50 m lower, at sea level, on the narrow strip of sand between the cliff and the sea, a "lower" pumped-storage lake cannot be created because there is no space for it. Here, however, a fluid storage facility, as described above, can be created, simply located in the sea. The upper water reservoir and the liquid reservoir in the sea are connected by a pipeline that runs via a turbine at sea level. At night, when electricity is needed and the sun isn't shining, the water from the upper pumped-storage lake flows through the turbine into the liquid storage facility, and the turbine produces electricity.During the day, when the sun is shining and the photovoltaic system produces more electricity than needed, this electricity is used to pump the water from the liquid storage facility back into the upper pumped-storage lake on the plateau. This energy storage system has an efficiency of up to 90%, while a battery storage system has a maximum efficiency of approximately 60%. Furthermore, storing electricity in lithium batteries is either not environmentally friendly or not very environmentally friendly. Another application for the liquid storage system of the present invention is described below.

[0065] Seawater desalination plants are usually operated by large coastal cities where water is scarce. A seawater desalination plant operates most economically and technically most smoothly when operated 24 hours a day, continuously and without interruption. This means that the seawater desalination plant produces the same amount of drinking water every hour. However, water consumption follows a different rhythm. A lot of water is used in the morning and evening, little during the day, and almost none at night. Therefore, the water produced at night must be stored. A correspondingly large water reservoir on land would be extremely expensive, and in many cases there is simply not enough space for such storage in a large city. A liquid storage facility in the sea, as described above, directly next to the seawater desalination plant, can be of great advantage.

[0066] In this regard, the present invention further relates to a third system comprising a previously described liquid reservoir and a seawater desalination plant. The liquid reservoir is arranged entirely underwater in a sea and connected to the seawater desalination plant in such a way that water desalinated by the seawater desalination plant can be fed into the liquid reservoir. Thus, the desalinated water (drinking water) can be stored in the liquid reservoir and used at a later time. The seawater desalination plant can preferably be arranged directly next to the sea. The third system can further comprise a photovoltaic system, which is in particular positioned directly next to the seawater desalination plant. The seawater desalination plant can be operated with the electricity produced by the photovoltaic system.

[0067] It should be noted that in the second plant, the desalinated water can also be stored in another liquid storage tank located under the water of the body of water, in particular the sea, with at least one flexible bag.

[0068] Another application for the liquid reservoir of the present invention is described below.

[0069] In subtropical regions, where 80% of annual rainfall occurs during a monsoon lasting just 6 weeks, municipalities often collect the so-called "run-off water" (so-called "water harvesting") that accumulates on a city's sealed surfaces. The water is usually stored in an artificial lake (fluid reservoir) and used during the dry season to irrigate parks, etc. In such an existing "greywater" reservoir, drinking water can now also be stored very cost-effectively using a liquid storage system as described above. This allows a sustainable municipal water management system to be optimized.

[0070] In this respect, the present invention relates to a fourth system comprising a previously described liquid reservoir and a fluid reservoir for storing a fluid (liquid), in particular water. The liquid reservoir is arranged entirely beneath the fluid, in particular beneath the water, of the fluid reservoir.

[0071] According to one variant, the fluid reservoir can be an artificial lake for storing grey water, in particular run-off water, whereby the liquid reservoir is used for storing drinking water.

[0072] According to a further variant, the fourth system preferably comprises a water treatment system or the fourth system is designed as a water treatment system. In this case, the water treatment system comprises the fluid reservoir. The fluid reservoir is connected to the liquid reservoir in such a way that water from the fluid reservoir can be conducted into the liquid reservoir for treating the water in the liquid reservoir. This means that at least one cleaning stage takes place in the liquid reservoir. If the liquid reservoir has a plurality of flexible bags that are in fluid communication with one another, a plurality of cleaning stages can take place in the liquid reservoir. In particular, one cleaning stage can take place in each bag. In other words, the number of cleaning stages that take place in the liquid reservoir advantageously corresponds to the number of bags. Advantageously, one cleaning stage can take place in the fluid reservoir itself.The fluid reservoir can advantageously be a basin that can be built in and / or on the ground. For example, the water treatment plant can have four purification stages, with the first purification stage taking place in the fluid reservoir and the third purification stage taking place in three bags of the liquid reservoir. This can result in enormous cost savings, especially since it avoids any potential idle capacity when using different basins for the different purification stages.

[0073] The advantages of such a system are evident from the following explanation of a typical water treatment system.

[0074] A water treatment plant usually operates with several tanks in which the water is treated, as the process takes place in several stages. Using a previously described liquid reservoir, a main tank (fluid reservoir) can be created in which the first (most contaminated) water stage is treated. Within this tank, for example, two or three previously described liquid reservoirs can be created, in which each individual water stage can be treated separately from the other water stages. This saves considerable costs and, above all, a lot of storage space. For example, if the main tank is 10,000 m 3 from a large downpour, a volume of 9000 m 3 After an initial pre-treatment, for example, 3000 m 3into a first liquid reservoir located in the main basin or below the rainwater in the main basin. Thus, the water in the main basin outside the first liquid reservoir is reduced to 6000 m 3 . In total, however, there are still 9000 m 3 Water in the main basin. After a further treatment period, the 3000 m 3 from the first liquid reservoir to a second liquid reservoir, and the first liquid reservoir can again be, for example, 3000 m 3 Water from the first purification stage, i.e. from the main basin. A total of 9000 m 3Water in the main tank. This can then be continued with a further, final purification stage in a third liquid reservoir. When empty, the first liquid reservoir, the second liquid reservoir, and the third liquid reservoir take up hardly any space. Thus, in this example, the main tank can ultimately complete all four purification stages using three liquid reservoirs and requires only about one-third the storage space compared to separate reservoirs in which the four purification stages take place.

[0075] The basic principle for all of the systems described is that arranging the liquid reservoir beneath a fluid in a fluid reservoir, particularly water in a water reservoir, or water in a body of water, has the decisive advantage over arranging it on land in that at least one flexible bag of the liquid reservoir beneath the fluid in the fluid reservoir or water in the body of water is protected from various environmental influences. For example, when using the bag on land, it would be advisable to protect it from rodents such as rats, beavers, or mice. If a small hole were to appear, there is a risk that the bag would lose liquid. Due to the relatively high pressure in the bag, even a small perforation could tear further, and the bag would be destroyed within a short time.Another important advantage of placing a bag made of foil pieces underwater is that a liquid storage facility made of foil on land would be impossible due to the high pressure load at the joints, particularly the welds, between the foil pieces. Underwater, there is no internal pressure on the walls and joints of the bag, as the external water pressure always balances the internal pressure. If there were no external water pressure, enormous internal pressure would build up, which would require an extremely thick foil. Thus, placing the bag under the fluid of a fluid storage facility, especially water from a water reservoir, or water from a body of water, prevents a bursting bag from causing a tidal wave, which would pose a danger to the surrounding area.Even in an uninhabited area, such a flood would not be without danger, as at that very moment, tradesmen could be dealing with a leak in the bag, for example.

[0076] Even termites could pose a threat to at least one of the bags of the liquid storage device if the bag is filled with water and located on land. Therefore, from this perspective, placement beneath the fluid of a fluid storage device, especially water from a water reservoir or water from a body of water, has proven advantageous. Even if the material of the bag is waterproof, a certain degree of permeability allows a certain amount of moisture to penetrate the film to the outside. Termites would then detect the water inside the bag and could chew through the bag to access the moisture.

[0077] If at least one of the flexible bags of the liquid storage device were placed underwater, a small perforation in the bag might not tear further when filled with water, as there is no pressure on the bag. This liquid storage device sits "weightless" in the water, so to speak. It is to be expected that a small perforation in the bag would not cause water to leak from the bag. Particularly if fresh water is used in the bag and the bag is immersed in salt water, it should be noted that salt water is heavier than fresh water, and for this reason, a small hole in the bag would result in hardly any fresh water leaking into the sea.

[0078] These advantages of placement beneath the fluid of a fluid reservoir, particularly water from a reservoir, or water from a body of water, compared to placement on land also mean that the bags can be constructed with correspondingly thin or weak material. This reduces the overall weight, overall costs, and resource consumption.

[0079] Furthermore, in the underwater arrangement, no pressure builds up in the liquid reservoir when it is pumped full. If the liquid reservoir were located above ground, then as it slowly fills, the building-up of the weight pressure of the water in the liquid reservoir would have to be overcome. This consumes energy. Such a mechanism does not exist underwater. Filling or emptying the liquid reservoir is always pressure-neutral.

[0080] As already mentioned, placing the bags under the fluid of a fluid reservoir, especially water from a reservoir, or water from a body of water also offers the advantage that the bags are exposed to no or significantly less sunlight than on land. Depending on the materials used, exposure to sunlight on the bags can significantly shorten their lifespan, especially if a plastic film is used.

[0081] Furthermore, when placed beneath the fluid of a fluid reservoir, particularly water in a water reservoir or water in a body of water, solar radiation results in significantly smaller temperature differences at the fluid reservoir than when placed on land. A film exposed to the sun, as an example material for the bag, is ideally always black so that no UV light penetrates the film, but instead "remains stuck" in the outermost layer of the film. However, a black film heats up relatively quickly when exposed to sunlight to 70°C or more, especially in southern regions of the earth. If the outermost layer of the film, where sunlight is converted into heat, heats the film to a thickness of a few tenths of a millimeter, but the film is in contact with the water inside (which has a temperature of 20°C, for example), enormous forces would arise due to the differential expansion of the material.The outer part of the film would try to expand, while the inner part would retain its expansion. If applied over a large area, tensile forces would occur that could potentially tear the film. Expansion due to temperature releases compressive forces that can be enormous. Over an area of ​​several thousand square meters, the tension between the outer part of the film and the inner part would be enormous. The storage device might not be able to withstand this, or would have to be designed to be correspondingly stable and thus resource-intensive. This idea, namely the reduced temperature fluctuation when arranged beneath the fluid of a fluid storage device, in particular water from a water reservoir, or water from a body of water, thus results in a decisive advantage for such an arrangement.

[0082] Furthermore, temperature fluctuations between day and night must be considered, as these can lead to damage to the film. If the outer area of ​​the film wants to expand during the day but the inner area doesn't, and the expansion forces are reversed at night, hairline cracks could develop in the film. At night, the liquid, especially the water, in the reservoir would certainly be warmer than the outside temperature, so that expansion could occur on the inside of the film at night, which the outer layer of the film might not be able to accommodate. Constant changes from day to night could therefore cause corresponding damage to the film.This effect, namely the temperature fluctuation between day and night, is not or to a much lesser extent decisive for the stress on the material when the liquid reservoir is arranged under the fluid of a fluid reservoir, in particular water of a water reservoir, or water of a body of water.

[0083] Furthermore, as already mentioned, it should be noted that by arranging the system under the fluid of a fluid reservoir, especially water from a water reservoir, or water from a body of water, no or less land is "consumed." In many regions of the world, land above water is insufficient, is very expensive, or can be used more effectively elsewhere.

[0084] On steep coasts where the sea crashes up against a rocky shore, there is a difference in elevation between the elevated area and sea level, but there is no space for a lower reservoir. In such a situation, for example, it is possible to arrange the liquid reservoir underwater in the body of water, i.e. in the sea, in particular with the at least one bag described in the context of the "first system". This can be fluidly connected via a suitable line to an upper reservoir, i.e. a fluid reservoir of any design. Here, too, the advantages of the liquid reservoir in the water, namely in particular the arrangement of the bag underwater, are exploited; as already described, the bag of the underwater liquid reservoir is protected from various environmental influences and temperature fluctuations and can be located in the water without pressure.

[0085] The costs, manufacturing effort, and resource requirements for arranging a liquid storage facility underwater in a body of water are many times lower than for a traditional reservoir in a pumped-storage power plant. It is particularly important to note that the liquid storage facility underwater in the body of water is not subject to any pressure loads and can therefore be designed simply, cost-effectively, and resource-efficiently. Therefore, the function of the liquid storage facility in the underwater arrangement must ensure that freshwater can be used. This offers a number of advantages, most notably the possibility of using freshwater turbines.

[0086] Comparing the liquid reservoir in the first system described above with the lower reservoir of a pumped-storage power plant reveals the following advantage: The liquid reservoir at the bottom of the body of water, especially the sea, is at the "lowest level," i.e., at or below sea level. When building a reservoir, even directly on the sea, a comparable level would require a lower reservoir, say 10 meters deep, at least 10 meters above sea level. This is because if the lower reservoir were pumped dry, the groundwater, which is always at least sea level near the coast, would lift the liner or other support of the reservoir. You can't build a reservoir in the groundwater because then you can't pump it dry. The bottom of a lower reservoir must therefore always be at least a few meters above sea level.The groundwater level at sea, for example, usually rises significantly above sea level during the monsoon. Even in such a case, this would potentially cause the reservoir bed to flood. Compared to a conventional reservoir, a liquid reservoir located underwater in a body of water provides at least 10 to 15 meters of storage height between the liquid reservoir and the fluid reservoir, if, as described above, the liquid reservoir is combined with a fluid reservoir designed as an upper reservoir on a cliff.

[0087] A further advantage of combining the liquid reservoir with a higher-level fluid reservoir (upper reservoir) is that when a liquid, particularly water, is released from the fluid reservoir into the liquid reservoir, no backpressure builds up in the liquid reservoir as the water level rises, as the reservoir is located underwater. In a classic pumped-storage power plant, the turbine or pump should always be positioned lower than the bottom of the lower reservoir so that all of the water in the lower reservoir can be captured, thus allowing the maximum pressure drop or maximum storage height to be utilized. However, the pressure difference then decreases as the water level in the lower reservoir rises. This is not the case when the liquid reservoir is arranged with at least one flexible bag underwater.This results in greater efficiency in the inventive arrangement of the liquid storage under water of the body of water.

[0088] As already apparent, the present invention relates to the use of a previously described liquid reservoir for storing a liquid, in particular water, in a body of water or a fluid reservoir. The liquid reservoir is arranged completely beneath the water of the body of water or beneath the fluid of the fluid reservoir.

[0089] On coasts with little rainfall and high population density (e.g. in California), the groundwater of the entire coastal region is often salinized because too much groundwater has been pumped up, causing the groundwater level to fall below sea level. This then results in seawater seeping into the groundwater. In coastal cities in such areas, attempts are made not to simply let rainwater from the sewer system flow into the sea, but to retain and store it for use in irrigation or drinking water treatment. However, large-scale water reservoirs are often not available for this purpose. In this case, a liquid reservoir as described above can be created in the sea offshore of the coastal community to store the surface water, which can then be processed again into drinking water. The liquid reservoir can therefore be used to store run-off water (surface water) and can be located in a sea.In particular, a system can be proposed that comprises a previously described liquid reservoir and a collection system for collecting run-off water, which is connected to the liquid reservoir in such a way that collected run-off water can be directed into the liquid reservoir. The liquid reservoir is arranged entirely under the water of a body of water, in particular the sea.

[0090] Further details, advantages, and features of the present invention will become apparent from the following description of exemplary embodiments with reference to the drawings. It shows:

[0091] Fig. 1 is a schematic simplified perspective view of a liquid reservoir for storing a liquid according to an advantageous embodiment of the present invention,

[0092] Fig. 2 is a schematic simplified side view of the liquid reservoir of Figure 1,

[0093] Fig. 3 is a schematic simplified plan view of the liquid reservoir of Figure 1,

[0094] Fig. 4 is a schematic simplified side view of the liquid reservoir from Figure

[0095] 1 in empty state,

[0096] Fig. 5 is a schematic simplified side view of the liquid reservoir of Figure 1 in full condition,

[0097] Fig. 6 is a schematic simplified perspective view of the liquid reservoir of Figure 1, showing further components of the liquid reservoir,

[0098] Fig. 7 is a schematic simplified view of a system according to a first embodiment of the present invention, comprising the liquid reservoir of Figure 1,

[0099] Fig. 8 is a schematic simplified view of a system according to a second embodiment of the present invention, which comprises the liquid reservoir of Fig. 1, and

[0100] Fig. 9 is a simplified schematic view of a system according to a third embodiment of the present invention, which includes a liquid reservoir according to the present invention. A liquid reservoir for storing a liquid, in particular water, according to an advantageous embodiment of the present invention is described in detail below with reference to Figures 1 to 6.

[0101] As can be seen from Figure 1, the liquid reservoir 100 comprises a flexible bag 1. In this exemplary embodiment, the liquid reservoir 100 comprises only one flexible bag 1 and is thus designed as such. The flexible bag 1 thus forms the fluid-absorbing volume of the liquid reservoir 100. However, it is also possible for the liquid reservoir 100 to be composed of several flexible bags 1 that are connected to one another in a fluid-conducting manner, so that the bags 1 form a total volume of the liquid reservoir 100. The fact that the bag 1 is flexible means in particular that the bag 1 can change its volume and adapt to the shape of the floor on which it is arranged. It should be noted that the bag 1 in Figure 1 is shown in a (arbitrarily but not completely) filled state.

[0102] Preferably, the flexible bag 1 has a storage capacity of at least 100 m 3, further preferably of at least 500 m 3 , further preferably of at least 1000 m 3 , further preferably of at least 5000 m 3 , on.

[0103] The flexible bag 1 is designed to be arranged completely underwater in a body of water and / or a fluid in a fluid reservoir, in particular underwater in a water reservoir. The body of water can be a sea, a lake, a river or pond. The fluid reservoir for storing a fluid is in particular a liquid reservoir for storing a liquid, preferably water. The fluid reservoir is in particular an open fluid reservoir, i.e. a fluid reservoir with an open side in which the liquid is in contact with the ambient air. The fluid reservoir can, for example, be an artificial reservoir or a basin, which is in particular arranged or built on and / or in the ground.

[0104] The flexible bag 1 is made from a plurality of film pieces. In particular, the bag 1 comprises a cover film 11, a base film 12, and a central region 13, which has a plurality of film rings 130, as can be seen in particular in Figures 1 and 2. The cover film 11, the base film 12, and the central region 13 are made of plastic, in particular HDPE.

[0105] The film rings 130 are welded to one another such that the central region 13 is designed in the shape of a bellows. In particular, the central region 13 has an even number of film rings 130. The cover film 11 and the bottom film 12 are welded to the central region 13, thus forming a storage space 10 for storing a liquid, in particular water. The storage space 10 corresponds to an interior of the flexible bag 1. It should be understood that the central region 13 is located between the cover film 11 and the bottom film 12 in the vertical direction 509 of the flexible bag 1. The vertical direction 509 of the flexible bag 1 is in particular a direction perpendicular to the cover film 11 and the bottom film 12.

[0106] Each foil ring 130 is welded at its outer edge region 131 and its inner edge region 132, as shown in Figure 2. For clarity, the outer edge region 131 and the inner edge region 132 of only one of the foil rings 130 are shown in Figure 2, namely the foil ring 130 adjacent to the base foil 12 or welded to the base foil 12.

[0107] In particular, the foil ring 130, which is adjacent to the base foil 12, is welded to the base foil 12 at its outer edge region 131 and to its adjacent foil ring 130 at its inner edge region 132. Furthermore, the foil ring 130, which is adjacent to the cover foil 11, is welded to the cover foil 11 at its outer edge region 131 and to its adjacent foil ring 130 at its inner edge region 132.

[0108] Each of the remaining foil rings 130, ie each foil ring 130 which is adjacent to foil rings 130 on both sides, is welded at its outer edge region 131 to an adjacent foil ring 130 and at its inner edge region 132 to another adjacent foil ring 130.

[0109] As a result, circumferential outer folds 135 and inner folds 136 are alternately formed in the vertical direction 509 of the liquid storage device 100 or the flexible bag 1. In this exemplary embodiment, the outer folds 135 and the inner folds 136 extend completely in the circumferential direction of the bag 1. By folding in and out the outer folds 135 and the inner folds 136, the volume of the flexible bag 1 or its storage space 10 can be changed.

[0110] As can be seen from Figure 2, the flexible sack 1, in particular the central region 13, is designed such that, when the sack 1 is full, an angle 501 between adjacent film rings 130, an angle 502 between a film ring 130 of the central region 13 and the cover film 11 welded to this film ring 130, and an angle 503 between a further film ring 130 of the central region 13 and the bottom film 12 welded to this further film ring 130 are each a maximum of 20 degrees, preferably a maximum of 10 degrees, furthermore preferably a maximum of 5 degrees. Thus, when the sack 1 is full, a bend in the film rings 130 can be kept within a range that has a positive influence on the welds of the film rings 130 and thus the longevity of the sack 1. The bend in the film rings 130 is shown in Figure 2. Since the foil rings 130 do not bend at a single bending point, stress concentration points in the foil rings 130 can be avoided.In particular, the bending of any foil ring 10 is distributed across the entire width 504 of the foil ring 130. For example, the bending curve of the foil rings 130 can have the shape of a sine curve or approximate the shape of a sine curve. For better clarity of the drawings, the bending of the foil rings 130 is not shown in Figures 1, 5, and 6.

[0111] Referring to Figures 1 and 3, the cover film 11, the base film 12, and the film rings 130 each have an outer contour without corners, in particular in the form of a rounded rectangle. Other shapes, such as a circular or oval shape, are also possible for the outer contour of the cover film 11, the base film 12, and the film rings 130. The absence of corners allows stress zones to be avoided, resulting in improved robustness of the bag 1.

[0112] According to Figures 2 and 3, the width 504 of each film ring 130 can be between 0.3 m and 2.2 m, preferably between 0.7 and 1.8 m, particularly preferably between 1 m and 1.5 m. Furthermore, a ratio of the width 504 of each film ring 130 to a length 505 of an opening 133, which an inner edge 134 of the corresponding film ring 130 encloses, can be between 0.02 and 0.2, preferably between 0.04 and 0.06 (Figure 3). In addition, a ratio of the width 504 of each film ring 130 to a width 506 of the opening 133, which the inner edge 134 of the corresponding film ring 130 encloses, can be between 0.03 and 0.06, preferably between 0.04 and 0.05.

[0113] According to Figure 2, a height distance 507 between adjacent outer folds 135 of the bag 1 can be a maximum of 0.40 m, preferably a maximum of 0.25 m when the bag 1 is completely filled with liquid. Furthermore, the height distance 507 between adjacent outer folds 135 of the bag 1 can be in a ratio to a height 508 of the liquid reservoir 100 or of the bag 1 of a maximum of 1 to 8, preferably a maximum of 1 to 10, preferably a maximum of 1 to 20, preferably a maximum of 1 to 40, when the bag 1 is completely filled with liquid. This can prevent a large or excessive bending of the film rings 130, particularly with a given width 504 of the film rings 130. The height distance 507 is the same in the circumferential direction of the bag 1.

[0114] In Figure 4, the bag 1 is shown empty, whereas in Figure 5 the bag 1 is in a completely filled state. As can be seen from Figures 1, 4 and 5, the bag 1 is designed such that the cover film 11 and the bottom film 12 are arranged parallel to one another at any fill level of the bag 1, in particular when the bag 1 is completely filled with liquid. However, it is also possible for the bag 1 to be designed such that the cover film 11 and the bottom film 12 are not parallel but inclined to one another, in particular when the bag 1 is completely filled with liquid. This can be particularly advantageous if the bag 1 has to be arranged on an inclined floor or floor region of a fluid reservoir or a body of water.

[0115] Figure 6 shows the liquid reservoir 100 or the flexible bag 1 with additional components that are not shown in the previous figures for the sake of clarity.

[0116] The flexible bag 1 further comprises a distance limiting device 2.

[0117] The distance limiting device 2 is designed such that, when the bag 1 is filled with liquid, in particular when the bag 1 is completely filled with liquid, a height distance 507 between adjacent outer folds 135 is less than or equal to a predetermined distance. Thus, the unfolding of the flexible bag 1 per outer fold 135 can be limited. This prevents excessive bending of the film rings 130 when the bag 1 is filled with liquid, which could lead to damage to the flexible bag 1 at the weld points between the film rings 130, the cover film 11, and the base film 12.

[0118] The distance limiting device 2 preferably has a plurality of connecting pieces 21 and a plurality of connecting elements 22. The connecting pieces 21 are, for example, tabs, wherein the connecting elements 22 are each designed as a cable. A plurality of connecting pieces 21 are arranged, preferably welded, on each outer fold 135, which are arranged in the circumferential direction of the bag 1, in particular at predetermined intervals. For illustrative purposes, only one connecting piece 21 per outer fold 135 is shown in Figure 2. The connecting pieces 21 are preferably evenly distributed in the circumferential direction of the bag 1.

[0119] The connecting pieces 21 between adjacent outer folds 135 are connected to one another by means of one of the connecting elements 22. In particular, at least one connecting piece 21 on an outer fold 135 and at least one connecting piece 21 on an adjacent outer fold 135 can be connected to one another by means of a connecting element 21. The distance limiting device 2 can ensure that bending of the film rings 130 when the bag 1 is filled with liquid, which could lead to damage to the flexible bag 1 at the weld points between the film rings 130, the cover film 11, and the bottom film 12, is always kept within a permissible range. The provision of the connecting pieces 21 and the connecting elements 22 also serves to ensure that the bag 1 unfolds as evenly as possible during the filling process and not more than permissible, whereby the stress on the bag 1 is also as even as possible.Furthermore, the bag 1 has an access opening 3 in the cover film 11 and a closure device 4 for closing and releasing the access opening 3. The storage space 10 of the bag 1 is accessible via the access opening 3, in particular for a cleaning robot or another device, for example an inspection device. The access opening 3 preferably has an area of ​​at least 400 cm. 2 , particularly preferably at least 900 cm 2 The closure device 4 can be designed, in particular, as an access hatch. For example, when the opening 3 is open, a robot can be inserted through it into the flexible bag 1 to clean the bottom of the bag 1 and inspect the bag 1 from the inside.

[0120] In addition, the bag 1 has a valve 5 which is designed to release air contained in the bag 1. In particular, the valve 5 is designed to open automatically in order to remove the air contained in the flexible bag 1. This allows any air that may be pumped into the flexible bag 1 to escape automatically. The valve 5 is also designed to release liquid contained in the flexible bag 1 if a predetermined (permissible) pressure value in the storage space 10 is exceeded. This ensures that the bag 1 is always under the permissible pressure. This means that if the pressure in the bag 1 is too high, the valve 5 can release as much liquid until the pressure prevailing in the bag 1 is less than or equal to the predetermined pressure value.

[0121] From Figure 6 it can further be seen that the bag 1 also has a fixing weight receiving device 6 for receiving a fixing weight 60 for fixing the bag 1 to a bottom of the body of water and / or the fluid reservoir.

[0122] The fixing weight receiving device 6 is designed such that it can also serve as an anchoring device 7 for anchoring the bag 1 to a bottom of the body of water and / or the fluid reservoir if anchoring points are present in the fluid reservoir or body of water.

[0123] In this exemplary embodiment, the fixing weight receiving device 6 has at least one tab 60, which is attached, in particular welded, to the flexible bag 1. The at least one tab 60 can be weighted with the fixing weight 61 and / or, if anchoring points are present in the fluid reservoir or body of water, can be fastened to the anchoring points, for example by means of a rope. In particular, a plurality of tabs 60 can be provided, which are distributed at predetermined intervals, in particular evenly, in the circumferential direction of the bag 1. Due to the described structure of the flexible bag 1, stress fields can be avoided when the bag 1 is folded in and out during emptying or filling.The proposed flexible bag 1 with the bellows-shaped central region 13 offers the further advantage that it can be filled and emptied without the cover film 11 and the base film 12 expanding or shrinking, or attempting to wrinkle. Thus, the flexible bag 1 can be manufactured to be robust and durable.

[0124] Figure 7 shows a system 1000 according to a first embodiment of the present invention, which comprises the liquid reservoir 100 from Figure 1.

[0125] In particular, the liquid reservoir 100 is part of an energy storage device 1001, wherein the energy storage device 1001 further comprises a fluid reservoir 300 for storing fluid. The liquid reservoir 100 is designed, in particular, as an upper reservoir for storing water. The fluid reservoir 300 is located, for example, on a cliff.

[0126] The system 1000 further comprises a turbine 8 fluidly connected to the fluid reservoir 300 and an electric machine 14. The fluid reservoir 100 is fluidly connected to the turbine 8 in a closed system, so that the fluid from the fluid reservoir 300 can be conducted through the turbine 8 to drive the turbine 8 and can be absorbed by the flexible bag 1. The electric machine 14 is driven by the turbine 8 to generate electrical current.

[0127] As can further be seen from Figure 7, the liquid reservoir 100 is lower than the fluid reservoir 300 and is arranged completely underwater in a body of water 200, in particular a sea.

[0128] It is intended that the turbine 8 is operable to pump the fluid from the liquid reservoir 100 into the fluid reservoir 300; preferably using the electric machine 14 as an electric motor to drive the turbine 8. However, an additional pump can also be provided to pump the fluid from the liquid reservoir 100 into the fluid reservoir 300.

[0129] The system 1000 also includes a photovoltaic system 16, which advantageously has floating bodies 17. The modules 18 for generating electricity are located on the floating bodies 17.

[0130] The photovoltaic system 16 floats on the water surface 201 and is located vertically above the liquid reservoir 100. The photovoltaic system 16 is attached to the waterbed 202 via corresponding anchors 19. The system 1000 also includes a seawater desalination system 400. The seawater desalination system 400 is located next to the photovoltaic system 16. Via an inlet 401, the seawater desalination system 400 can suck water from the body of water 200, partially desalinate it, and return it to the body of water 200 via the outlet 402. The desalinated water can be transported ashore via a drinking water pipeline (not shown) or can be collected and retrieved by a watercraft.

[0131] The photovoltaic system 16, the seawater desalination system 400, and the electric motor 14, as well as the optional additional pump (not shown), are electrically connected to one another. As a result, the electrical energy generated by the photovoltaic system 16 can be used both directly in the seawater desalination system 400 and stored in the energy storage device 1001. The electricity generated by the energy storage device 1001, in particular by the electric motor 14, can be used in the seawater desalination system 400.

[0132] In a modification of the system 1000, the photovoltaic system 16 can be arranged on land, in particular directly next to the fluid storage 300 (shown in dashed lines).

[0133] Figure 8 shows a system 1000 according to a second embodiment of the present invention, which includes the liquid reservoir 100 from Figure 1. The liquid reservoir 100 is arranged underwater in a body of water 200, in particular a sea.

[0134] The system 1000 further comprises a seawater desalination system 400, which is connected to the flexible bag 1 of the liquid storage unit 100 via a water pipeline 403. Desalinated water produced by the seawater desalination system 400 is fed into the bag 1 via the water pipeline 403 and stored there. When the water is needed, it can be pumped out of the bag 1, for example, using a pump (not shown).

[0135] By storing the desalinated water in water body 200, in particular under the water of water body 200, a correspondingly large water reservoir on land can be dispensed with.

[0136] Figure 9 shows a system 1000 according to a third embodiment of the present invention, which comprises a liquid reservoir 100 from Figure 1. In this embodiment, the liquid reservoir 100 is composed of a plurality of flexible bags 1, in particular three bags 1. The plurality of flexible bags 1 are fluidically connected to one another, so that the bags 1 form a total volume of the liquid reservoir 100. All bags 1 are designed like the previously described bag 1. The bags 1 are arranged in series, so that an outlet of one bag 1 is fluidically connected to the inlet of the next bag 1.

[0137] The system 1000 here comprises a water treatment system 600, which includes the fluid reservoir 300. The fluid reservoir 300 is, in particular, a basin built into the ground 700, in which the bags 1 are arranged. The fluid reservoir 300 is filled with water to be treated.

[0138] The fluid reservoir 300 is connected to the liquid reservoir 100 such that water from the fluid reservoir 300 can be conducted into the liquid reservoir 100 for treating the water in the liquid reservoir 100.

[0139] It is possible for a first cleaning stage to take place in the fluid reservoir 300 itself, with a second cleaning stage being realized in the first bag 1 in the flow direction from the fluid reservoir 300 to the liquid reservoir 100.

[0140] Figure 9 shows the first bag 1 in the flow direction from the fluid reservoir 300 to the liquid reservoir 100 in the filled state, while the second bag 1 and third bag 1 in the flow direction from the fluid reservoir 300 to the liquid reservoir 100 are shown in the empty state. A third cleaning stage takes place in the second bag 1, and a fourth cleaning stage takes place in the third bag 1.

[0141] The treated water can be stored in particular in the third bag 1 itself, in a fourth bag 1 of the liquid reservoir 100 or in a bag 1 of a further liquid reservoir 100 in the fluid reservoir 300.

[0142] This eliminates the need for separate tanks for the second, third and fourth cleaning stages, resulting in significant cost savings.

[0143] In addition to the above written description of the invention, reference is hereby explicitly made to the drawings in the figures for its supplementary disclosure. List of reference symbols

[0144] 1 bag

[0145] 2 Distance limiting device

[0146] 3 Access opening

[0147] 4 locking device

[0148] 5 Valve

[0149] 6 Fixing weight holder

[0150] 7 Anchoring device

[0151] 8 turbines

[0152] 10 storage space

[0153] 11 Cover film

[0154] 12 floor foil

[0155] 13 Middle area

[0156] 14 electric machine

[0157] 16 photovoltaic systems

[0158] 17 floats

[0159] 18 modules

[0160] 19 Anchoring

[0161] 21 connecting piece

[0162] 22 Connecting element

[0163] 60 tab

[0164] 61 Fixing weight

[0165] 100 liquid storage

[0166] 130 foil ring

[0167] 131 outer edge area

[0168] 132 inner edge area

[0169] 133 Opening

[0170] 134 inner edge

[0171] 135 outer fold

[0172] 136 inner fold

[0173] 200 bodies of water

[0174] 201 Water surface

[0175] 202 Waterbed 300 Fluid reservoir

[0176] 301 Fluid storage floor

[0177] 400 seawater desalination plant

[0178] 401 inlet

[0179] 402 Expiration

[0180] 403 Water pipeline

[0181] 501 angles

[0182] 502 angles

[0183] 503 angles

[0184] 504 width

[0185] 505 length

[0186] 506 width

[0187] 507 height difference

[0188] 508 height

[0189] 509 Altitude direction

[0190] 600 water treatment plant

[0191] 700 soil

[0192] 1000 system

[0193] 1001 energy storage devices

Claims

Claims 1 . Liquid reservoir (100) for storing a liquid, in particular water, comprising at least one flexible bag (1) which is designed to be arranged completely under the water of a body of water (200) and / or under a fluid of a fluid reservoir (300), in particular under the water of a water reservoir.

2. Liquid storage device (100) according to claim 1, wherein the at least one flexible bag (1) comprises: • a cover film (11), • a floor foil (12), and • a central region (13) comprising a plurality of film rings (130) made of plastic, in particular HDPE, which are welded to one another in such a way that the central region is designed in the form of a bellows, wherein the cover film (11) and the base film (12) are welded to the central region (13) so that a storage space (10) for storing a liquid, in particular water, is formed.

3. Liquid storage device (100) according to claim 1 or 2, wherein each foil ring (130) is welded at its outer edge region (131) and at its inner edge region (132).

4. Liquid storage device (100) according to claim 2 or 3, wherein, when the bag (1) is completely filled with liquid, an angle (501) between adjacent film rings (130) and / or an angle (502) between a film ring (130) of the central region (13) and the cover film (11) welded onto this film ring (130) and / or an angle (503) between a further film ring (130) of the central region (130) and the bottom film (12) welded onto this further film ring (130) is / are a maximum of 20 degrees, preferably a maximum of 10 degrees, further preferably a maximum of 5 degrees.

5. Liquid storage device (100) according to one of claims 2 to 4, wherein a width (504) of each film ring (130) is between 0.3 m and 2.2 m, preferably between 0.7 and 1.8 m, particularly preferably between 1 m and 1.5 m and / or a ratio of the width (504) of each film ring (130) to a length (505) of an opening (133) which an inner edge (134) of the corresponding film ring (130) encloses is between 0.02 and 0.2, preferably between 0.04 and 0.06, and / or a ratio of the width (504) of each film ring (130) to a width (506) of the opening (133) which the inner Edge (134) of the corresponding foil ring (130) is between 0.03 and 0.06, preferably between 0.04 and 0.

05.

6. Liquid storage device (100) according to one of claims 2 to 5, wherein the cover film (11) and the bottom film (12) are arranged parallel or inclined to one another, in particular when the bag (1) is completely filled with liquid.

7. Liquid storage device (100) according to one of claims 2 to 6, wherein the cover film (11) and / or the base film (12) and / or the film rings (130) each have / have an outer contour without corners, in particular in the form of a rounded rectangle.

8. Liquid reservoir (100) according to one of claims 2 to 7, wherein the central region (13) has an even or odd number of foil rings (130).

9. Liquid storage device (100) according to one of claims 2 to 8, wherein the cover film (11) and the base film (12) are plastic films, in particular made of HDPE.

10. Liquid storage device (100) according to one of claims 2 to 9, wherein, when the bag (1) is completely filled with liquid, a height distance (507) between adjacent outer folds (135) of the bag (1) is at most 0.40 m, preferably at most 0.25 m, and / or is in a ratio to a height (508) of the liquid storage device (100) of at most 1 to 8, preferably of at most 1 to 10, preferably of at most 1 to 20, preferably of at most 1 to 40.

11. Liquid storage device (100) according to one of claims 2 to 10, further comprising a distance limiting device (2) which is designed such that, when the bag (1) is filled with liquid, a height distance (507) between adjacent outer folds (135) of the flexible bag (1) is less than or equal to a predetermined distance.

12. Liquid storage device (100) according to one of claims 2 to 11, further comprising a plurality of connecting pieces (21) and a plurality of connecting elements (22), wherein at least one of the connecting pieces (21) is arranged on each outer fold (135) of the flexible bag (1), and the connecting pieces (21) between adjacent outer folds (135) are connected to one another by means of one of the connecting elements (22), preferably wherein a plurality of connecting pieces (21) are arranged on each outer fold (135), which are arranged in the circumferential direction of the bag (1), in particular at predetermined intervals.

13. Liquid storage device (100) according to one of the preceding claims, wherein the flexible bag (1) has a storage capacity of at least 100 m 3 , further preferably of at least 500 m 3 , further preferably of at least 1000 m 3 , further preferably of at least 5000 m 3 has.

14. Liquid reservoir (100) according to one of the preceding claims, further comprising an access opening (3) through which an interior of the flexible bag (1) is accessible, in particular for a cleaning robot, and a closure device (4) for closing and releasing the access opening (3).

15. Liquid reservoir (100) according to one of the preceding claims, comprising at least one valve (5) which is designed to release air located in the flexible bag (1) and / or which is designed to release liquid located in the flexible bag (1) when a predetermined pressure value in the flexible bag (1) is exceeded.

16. Liquid reservoir (100) according to one of the preceding claims, comprising a fixing weight receiving device (6) for receiving a fixing weight (60) for fixing the liquid reservoir (100) to a bottom of the body of water (200) and / or the fluid reservoir (300) and / or an anchoring device (7) for anchoring the liquid reservoir (100) to a bottom of the body of water (200) and / or the fluid reservoir (300).

17. Annex (1000), comprising: • a fluid reservoir (300), in particular designed as an upper reservoir, for storing fluid, preferably water, • a turbine (8) connected to the fluid reservoir (300) in a fluid-conducting manner, • a liquid reservoir (100) according to one of claims 1 to 16, which is fluidly connected to the turbine (8) in a closed system, so that the fluid from the fluid reservoir (300) can be conducted through the turbine (8) to drive the turbine (8) and can be absorbed by the flexible bag (1) of the liquid reservoir (100), • and an electric machine driven by the turbine (8) for generating electric power, • wherein the liquid reservoir (100) is arranged lower than the fluid reservoir (300) and completely underwater in a body of water (200), in particular a sea.

18. System (1000) according to claim 17, wherein • the turbine (8) is operable to pump the fluid from the liquid reservoir (100) into the fluid reservoir (300), preferably using the electric machine as an electric motor to drive the turbine (8), • and / or wherein the system comprises an additional pump for pumping the fluid from the liquid reservoir (100) into the fluid reservoir (300).

19. Plant (1000) according to one of claims 17 and 18, comprising a photovoltaic system which is connected to the turbine (8) for supplying power to the turbine (8) and / or to the additional pump for supplying power to the additional pump.

20. Annex (1000), comprising: • a liquid reservoir (100) according to one of claims 1 to 16, and • a seawater desalination plant (400), wherein the liquid reservoir (100) is arranged completely under water of a sea and is connected to the seawater desalination plant (400) in such a way that water desalinated by the seawater desalination plant (400) can be conducted into the liquid reservoir (100).

21. Annex (1000), comprising: • a liquid reservoir (100) according to one of claims 1 to 16, and • a fluid reservoir (300) for storing a fluid, in particular water, wherein the liquid reservoir (100) is arranged completely under the fluid of the fluid reservoir (300).

22. System (1000) according to claim 21, comprising a water treatment system (600), wherein the water treatment system (600) comprises the fluid reservoir (300) and the fluid reservoir (300) is connected to the liquid reservoir (100) such that water from the fluid reservoir (300) can be conducted into the liquid reservoir (100) for treating the water in the liquid reservoir (100).

23. Use of a liquid reservoir (100) according to one of claims 1 to 16 for storing a liquid, in particular water, in a body of water (200) or a fluid reservoir (300), in particular a water reservoir, wherein the liquid reservoir (100) is arranged completely under the water of the body of water (200) or under the fluid of the fluid reservoir (300).

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