Arrangement for stabilising electricity grids, having caverns for gas storage

Abstract

The invention relates to an arrangement for stabilising an electricity grid (91) by means of an energy store. The energy store comprises a gas generator (2), fed by the electricity grid, for a gaseous fuel, in particular hydrogen, and a cavern (6) comprising a supply line (4) that reaches into the cavern (6). In order to store energy, gaseous fuel generated by the gas generator (2) is introduced into the cavern (6) via the supply line (4) and, in order to withdraw energy, is removed from the cavern (6). According to the invention, the supply line (4) is designed as a dual-directional line (5) that reaches into the cavern (6) and comprises in each case a filling line (51) and a separate removal line (52). This means that it is possible to feed in the gaseous fuel into the cavern (6) and to provide negative operating reserve with respect to the electricity grid (91) and, at the same time, to also remove the gaseous fuel from the cavern (6) by means of the separate removal line (52) for one of the use units (3), in order to generate methane by means of the methanation plant (33) or for a return flow (31). Inconvenient switching processes in the lines are not required and therefore the operating reserve can be provided rapidly. The filling line (51) and removal line (52) are preferably guided to the cavern (6) adjacently in two, optionally one, bored shaft(s).

Description

[0001] Arrangement for stabilizing electricity networks with cavern for gas storage

[0002] The invention relates to an arrangement for stabilizing electricity grids. The arrangement comprises an energy storage device designed as a cavern for gas storage. A gas generator fed by the electricity grid generates gas, in particular hydrogen, which can be stored in the cavern as a gas to store energy and can be withdrawn again as needed to release energy.

[0003] As part of the energy transition to renewable energies, the proportion of volatile and decentralized electricity generation is increasing, as is typical for power plants operated with renewable energy sources such as wind turbines or photovoltaic systems. In addition to the constant fluctuations on the load side, there are also increasingly dynamic fluctuations on the generation side. This also leads to temporary surpluses in generation, which subsequently requires measures as part of feed-in management, such as the curtailment of power plants. This often affects wind turbines because, unlike conventional power plants, they have a high power gradient and can therefore be curtailed quickly. This is not only critical from the point of view of the stability of the electricity grid, but also with regard to the loss of renewable energy that comes with the curtailment of wind turbines.It is unsatisfactory that the desired form of energy is not being fully exploited but limited, and that the potential for generating renewable energy is therefore wasted due to the enforced shutdown of the wind turbine. Storage is therefore needed for the electricity grids in order to be able to better adapt the fluctuating supply of electrical energy from renewable sources to demand and, if possible, to manage without curtailment. In addition to battery storage systems, which can generally only store small amounts of energy, and pumped storage power plants, which require a lot of space and whose construction represents a significant intervention in the landscape and correspondingly causes major problems for nature conservation, gas storage also plays a role. This means that when there is a surplus of electrical power, gas can be generated, for example hydrogen gas through electrolysis, and stored in the gas storage facility.In this way, a reserve is created that can be called upon when necessary, in the event of underproduction of electrical power or when power demand is high.

[0004] Such gas storage facilities are not necessarily restricted to one type of gas. The aforementioned hydrogen and natural gas (produced by methanation) from excess electrical energy are particularly suitable. In the case of hydrogen, for example, hydrogen is produced from excess electrical energy using an electrolyzer, and the hydrogen is stored in a cavern. Caverns are large underground cavities that are located in suitable geological layers and are gas-tight. They can be of natural origin or artificially created, as described, for example, in EP 2 855 306 A1. The gas (especially hydrogen) is stored in such a cavern via a connecting pipe under high pressure, typically 40 to 200 bar, stored there for an indefinite period of time, and withdrawn again via the connecting pipe when required.The concept enables the storage of large volumes of gas and thus correspondingly large amounts of energy. The concept has proven successful, particularly in gas grids with relatively long injection and withdrawal cycles. However, it is not sufficient to support the electricity grid fed by volatile, renewable energies and the associated high dynamic demands regarding the rapid provision of control energy and control power.

[0005] The invention is based on the object of providing an arrangement for stabilising electricity networks which is improved in terms of dynamics and which in particular avoids or reduces the reduction or shutdown of power plants operated with renewable energies, such as wind farms and wind turbines.

[0006] The inventive solution lies in the features of the independent claim. Advantageous further developments are the subject of the dependent claims.

[0007] In an arrangement for stabilizing an electricity network by means of an energy storage device, wherein the energy storage device comprises a gas generator for a gaseous fuel, in particular hydrogen, which is fed by the electricity network, and a cavern with a connecting pipe reaching into the cavern, wherein the gaseous fuel produced by the gas generator is introduced into the cavern via the connecting pipe in order to store energy and is removed from the cavern in order to release energy, the invention provides that the connecting pipe is designed as a dual-directional line reaching into the cavern, which in each case comprises a filling line and a separate removal line.

[0008] The invention is based on the idea of ​​enabling continuous and parallel storage and withdrawal by means of separate lines for filling and withdrawal, without the need for complicated switching operations on the lines and, in particular, without reversing the flow direction in the lines. "Parallel" is understood here to mean that storage overlaps with withdrawal. This allows for faster switching between storing gas (the gaseous fuel) in the cavern and withdrawing it from the cavern. The stabilization arrangement according to the invention therefore also meets high dynamic requirements, as is particularly necessary for electricity grids with a high proportion of volatile generation from renewable energies.

[0009] The arrangement according to the invention enables simultaneous storage and withdrawal processes, which was not possible in the prior art. Thanks to the invention, withdrawal is also possible at any time during filling. Thus, even when gas is withdrawn, continuous, unbuffered (without intermediate storage) filling can continue.

[0010] Due to the simultaneous filling and withdrawal, it is possible to respond to different requirements for energy intake and / or output with high dynamics. The arrangement according to the invention is suitable not only as a dynamic energy storage device, but also for the provision of rapid control power, both from the electricity grid and output to the electricity grid (negative or positive control power). The arrangement according to the invention is thus suitable for the provision of primary control power and, due to the large gas storage volume provided by the cavern, also for the longer-term provision of secondary control power or longer-running minute control power.Since caverns can be created efficiently in suitable geological formations or are already available through previous exploitation of natural gas fields, the invention enables all these advantages with significantly less effort than with conventional storage technologies, such as buffer batteries or pumped storage power plants.

[0011] The dual-directional line and its filling line are expediently designed for continuous feed-in, independent of withdrawal, and / or continuous withdrawal, independent of feed-in. This independence offers a number of advantages: firstly, it enables continuous drawdown of electrical power from the electricity grid, thus avoiding curtailment of the wind turbines even when there is a surplus of power in the grid. secondly, the option of continuous filling prevents the storage facility from running idle. thirdly, gas can be withdrawn at any time. The cavern thus serves as a large storage facility for reserve energy, from which electrical power can be provided and released at any time as needed.

[0012] Below we first explain some of the terms used:

[0013] Electricity networks can include, in particular, transmission and distribution networks, typically operated by one or more network operators in a country. This term does not include networks within buildings.

[0014] A gas generator is a device that uses electricity to produce a gaseous fuel. Fuel is commonly understood in the technical sense as a chemical substance whose stored energy can be converted into usable energy through combustion. This term encompasses, in particular, chemical fuels such as methane and electrochemical fuels such as hydrogen for electricity generation in fuel cells.

[0015] Caverns are underground cavities. They are gas-tight and can be of natural or man-made origin. Caverns are typically located in certain suitable geological strata.

[0016] The term “gas extracted from the cavern” refers to gas (gaseous fuel) which has been produced according to the invention by means of the gas generator and stored in the cavern.

[0017] The terms primary control power, secondary control power, and minute reserve power are technical terms used by grid operators, particularly those of transmission grids. They are defined in a professional manner in the regulations applicable to the respective transmission grids. This can vary from country to country or from control area to control area, so a specific specification of the respective criteria is not useful; instead, it is clearly evident to the expert from the relevant regulations.

[0018] It is advantageous that several different usage units for the gas extracted from the cavern are connected to the extraction line. In this way, the gas extracted from the cavern can optionally also be used in other ways. In addition to a device for reconverting the gas into electricity, in particular a fuel cell or a combined heat and power (CHP) plant, the usage units can in particular be a methanation plant designed to synthesize methane using the gaseous fuel (in particular hydrogen gas) extracted from the cavern, and / or a transfer point to a gas network at which the extracted gas is fed directly into the gas network. The gas network can in particular be a natural gas network. However, it should not be ruled out that it is a network for another gas, in particular hydrogen gas.

[0019] In order to be able to choose between the different usage units, at least one switchable gas switch is expediently connected to the extraction line, whereby the extracted gas (the gaseous fuel) flows to one of the different usage units depending on the switching state of the gas switch. It is advantageous if the gas switch is also designed to switch partial flows. In this way, part of the extracted gas can be used, for example, for re-conversion, while another part of the gas is led to another of the usage units 3, e.g. the methanation plant. The gas switch is preferably designed so that it can be switched even when extraction is in progress. This means that switching can take place without interrupting extraction from the cavern.

[0020] According to a particularly advantageous aspect of the invention, a controller for control power is provided which has an input for a signal for a target control power, in particular negative target control power, and which is designed to control the gas generator in such a way that power corresponding to the, in particular negative, target control power is taken from the electricity grid to generate gas which is stored in the cavern. In this way, the arrangement according to the invention with its cavern can participate in the provision of control power. The grid operator (or another higher-level location on or in the grid) transmits a signal for a requested control power (target control power). This often involves a request for negative control power, i.e. if power is produced too high, in particular by wind turbines, it is necessary to take the excess power from the grid.For this purpose, the grid operator issues a control signal for negative target control power. If this is applied to the control of the arrangement according to the invention, it draws more power from the grid in accordance with the requested target control power, generates gas from it, and stores it in the cavern. This allows a rapid response to a power surplus in the grid within seconds, particularly when an electrolyzer is used as a gas generator. Furthermore, due to the large volume of the cavern, the control power can be provided for a relatively long time, typically over 60 minutes, or even longer, over several hours.

[0021] It is also advantageous for the control system for control power to also influence a re-electrification facility in order to feed additional power into the electricity grid as positive control power. This essentially reverses the process described above. An additional power requirement arises in the grid and the grid operator issues a target signal for the feed-in of additional power (positive control power). The control system influences the re-electrification facility accordingly, for which gas is taken from the cavern (regardless of whether further gas is being stored at the same time). The re-electrification facility generates additional electrical power from the gas, for example by means of a fuel cell or a combined heat and power (CHP) plant, and feeds this into the grid (or supplies it to a consumer).This too can be carried out both very dynamically and over a longer period of time thanks to the cavern’s large storage volume. The cogeneration plant can, for example, be a hydrogen-powered gas turbine that drives an electricity generator. A switchable bypass line is expediently provided, which is connected to the filling line between the gas generator and the cavern and connects this to the extraction line. This can be used to feed gas produced by the gas generator directly to the usage unit (or one of the usage units) when required, without the gas first being introduced into the cavern. In this way, it is possible to react quickly to changes in the gas demand of one of the usage units. This can further increase the plant’s dynamics and improve efficiency.

[0022] Essentially, the cavern represents a large buffer for storing electricity. However, it may be expedient to optionally provide an additional buffer accumulator. This is fed by the electricity grid connected to the gas generator and is designed in particular for rapid power output and / or power consumption. This allows electrical energy to be provided particularly quickly when needed, similar to the bypass line with regard to the gas supply, thus increasing the dynamics with regard to the feed-in of electrical energy. Furthermore, the buffer accumulator can be used to stabilize and smooth the electrical supply to the gas generator, in particular to the electrolyzer.

[0023] Advantageously, the filling line and the withdrawal line are led into the cavern at a distance from one another. They are expediently at least 5 meters apart, although this distance can depend on the dimensions (in particular the diameter) of the filling and withdrawal lines. Preferably, the filling and withdrawal lines are arranged adjacent to one another; this means that the distance, based on the diameter, is between three times and thirty times the diameter, in particular at least ten times the diameter and more preferably at most twenty times the diameter. It can be advantageous to use an average diameter for this purpose; the average diameter is understood to be the average diameter of the filling line or the withdrawal line.The type of averaging must be selected professionally; it can be an arithmetic mean, a geometric mean or another type of averaging. Instead of the (average) diameter, a measure of the (average) width of the respective line can be used; this is particularly suitable, for example, for filling and / or extraction lines with a non-circular cross-section. Such a distance should ensure that the incoming gas does not have any harmful flow influences on the gas extraction and vice versa. This achieves better decoupling of the filling line from the extraction line and thus minimises the risk of the filling line and extraction line influencing each other. It is advisable, particularly when arranged next to one another, to provide separate boreholes for the filling line and the extraction line.

[0024] It can also be provided that the dual-directional line with its filling line and separate withdrawal line are arranged in a common borehole. In this case, the two lines for filling and withdrawal are no longer spaced from each other, but the functionality of withdrawal independent of storage or storage independent of withdrawal is still guaranteed. This space-saving design is particularly suitable for caverns that are relatively narrow at the top. Furthermore, combining the dual-directional line in one borehole simplifies production and thus reduces the production cost. It can expediently be provided that the filling line and the withdrawal line with their respective mouths reach different depths into the cavern, with the filling line preferably reaching deeper.In this way, the third dimension, namely the depth of the cavern, can be used to achieve improved decoupling between the filling line and the extraction line. If the extraction line is positioned with its outlet higher in the cavern, this facilitates the extraction of gas at low levels.

[0025] The cavern is expediently formed in a salt dome. Due to their geological properties, these are particularly suitable for gas-tight storage. In this respect, a cavern must be distinguished from a so-called pore storage. The cavern is pressure-resistant and is expediently designed for an operating pressure of at least 40 bar, preferably up to 200 bar. It has been shown that particularly favorable operation of the cavern is possible at this pressure range, particularly with regard to economical operating technology and geomechanical stability.

[0026] According to a further aspect, which may merit independent protection, the invention also extends to the cavern for storing gaseous fuel, wherein, according to the invention, the connecting pipe is designed as a dual-directional line extending into the cavern, each of which comprises a filling line and a separate extraction line, preferably adjacent to one another. Furthermore, for a more detailed explanation of the cavern with its dual-directional line, its further design, and its mode of operation, reference is made to the above description to avoid repetition.

[0027] The invention is explained below by way of example with reference to the accompanying drawings using advantageous embodiments. They show: Fig. 1 is a schematic view of a first embodiment;

[0028] Fig. 2 shows a diagram for the provision of control power;

[0029] Fig. 3 is a schematic view of a second embodiment; and

[0030] Fig. 4 is a schematic view of a third embodiment.

[0031] Figure 1 illustrates the invention using a first embodiment as an example. The arrangement for stabilizing an electricity grid, designated in its entirety by reference numeral 1, comprises as its main components a gas generator 2 and utilization units 3, which are connected to an underground cavern 6 via a pipe connection 4. The cavern 6 is located in a subterranean salt dome 90. The invention is explained using hydrogen as the example of the gas generated by the gas generator 2 as a gaseous fuel and stored in the cavern 6. It is understood that other gaseous fuels (e.g., methane) can also be used.

[0032] The stabilization arrangement 1 is connected to an electricity grid 91 via a system transformer 10; in the illustrated embodiment, this is a transmission grid of a grid operator. The gas generator 2 is connected to the system transformer 10 via a connecting line 12 and is supplied with electrical power via it. The gas generator 2 is designed to generate hydrogen gas using electrical power. This can be done in a manner known per se; the gas generator 2 is preferably designed as an electrolyzer. However, other electrically operated processes for generating hydrogen are also possible.

[0033] Furthermore, a combined heat and power plant (CHP plant) or a fuel cell 31, which is one of the utilization units 3, is connected to the plant transformer 10 via a further connecting line 13. Electrical power generated by the combined heat and power plant, e.g., an electricity generator driven by a hydrogen gas turbine, or a fuel cell 31, by reconverting hydrogen gas into electricity, can be fed into the transmission grid 91 via this connecting line 13.

[0034] The gas generator 2 and the utilization units 3 with the fuel cell 31 are connected to the cavern 6 via a pipe connection 4. According to the invention, the pipe connection 4 is designed as a dual-directional line 5, which includes a filling line 51 and a withdrawal line 52.

[0035] The filling line 51 is connected to the gas generator 2 and ends with its mouth 53 in the cavern. Hydrogen gas generated by the gas generator 2 is stored in the cavern 6 through it. The extraction line 52 is designed separately from the filling line 51. Its mouth 54 also projects into the cavern 6 and leads from the cavern 6 upwards to the usage units 3 with the fuel cell 31. In the first embodiment shown in Figure 1, the two lines of the dual-directional line 5, the filling line 51 and the extraction line 52, are spaced apart from one another but adjacent to one another and led into the cavern 6. This ensures that effects such as flow turbulence occurring at the mouth 53 of the filling line 51 do not affect the flow behavior of the hydrogen gas flowing from the cavern into the mouth 54 of the extraction line 52.The separate design of the filling line 51 from the withdrawal line 52 enables independent filling and withdrawal. In this way, hydrogen gas can continue to be fed into the cavern 6 via the filling line 51, regardless of whether hydrogen gas is withdrawn via the separate withdrawal line 52 or not. The same applies conversely; hydrogen gas can be withdrawn via the separate withdrawal line 52 and supplied to the usage units 3, regardless of whether hydrogen gas is simultaneously being stored in the cavern 6 via the filling line 51 or not.

[0036] The usage units 3 can have, in addition to the fuel cell 31, further units for using the hydrogen gas. For example, a methanation plant 33 can also be provided, which synthesizes methane gas from the supplied hydrogen gas with the addition of carbon dioxide, which can be taken from the air in particular as CO2. This can be fed into a natural gas network 93 (shown only symbolically) in a manner known per se. Furthermore, as a further usage unit, it can be provided that the hydrogen gas taken from the cavern 6 via the extraction line 52 is fed into a gas network, which can be a natural gas network or a hydrogen gas network (not shown), via a transfer point 35. In this way, direct use of the stored hydrogen is also possible.

[0037] In order to enable the operator of the arrangement to choose between the various types of use, a gas switch 30 is provided on the extraction line 52. It is connected upstream of the usage units 3 and determines which of the usage units 3 the hydrogen gas extracted from the cavern 6 via the extraction line 52 is supplied to, namely the fuel cell 31, the methanation plant 33 or at the transfer point 35 for direct supply. Optionally, the gas switch 30 is capable of partial flow, which means that it divides the hydrogen gas flow coming from the extraction line 52 so that more than one of the usage units 3 is supplied with hydrogen gas, e.g. the fuel cell 31 and the methanation plant 33 receive the extracted hydrogen gas.

[0038] Also provided is a controller 8 of the arrangement which is designed in particular to provide control power for the electricity grid 91. For this purpose, a setpoint input 80 is provided, to which a signal for a requested control power can be applied by an operator of the electricity grid 91 or by another higher-level authority (not shown). The controller 8 is further connected to the fuel cell 31 via a first signal line 81 and to the gas generator 2 via a second signal line 82 and thus influences their operation. If the grid operator requests, for example, positive control power, the controller 8 controls the fuel cell 31 via the signal line 81 in such a way that it generates more electrical power and correspondingly withdraws more hydrogen gas from the cavern 6 via the withdrawal line 52.Thanks to the dual-directional line 5, this is possible at any time, regardless of whether the gas generator 2 is simultaneously feeding hydrogen gas into the cavern 6 via the filling line 51 or not. This allows for a very rapid response to a request for control power, namely within seconds. Switching gas connections or changing the direction of a (possibly long) connecting pipe to the cavern is not necessary.

[0039] The same applies to the reverse case, when negative control power is requested via the setpoint input 80. For this purpose, the controller 8 controls the gas generator 2 via the signal line 82, which draws more electrical power from the electricity network 91 and, by means of the electrolyzer, produces more hydrogen gas, which is fed via the filling line 51 into the cavern 6 and temporarily stored there. This can take place regardless of whether or not hydrogen gas is being withdrawn via the withdrawal line 52 at this time. Thus, in the practically particularly important case when surplus power is present in the electricity network 91, the surplus power can be quickly and effectively removed from the electricity network 91 by means of the arrangement according to the invention and stored as hydrogen gas in the cavern 6.This energy is then available again at any time, for example by reconversion to electricity using the fuel cell 31 or for use in another way, for example by means of the methanation plant 33 (or by direct feed into a gas network via the transfer point 35).

[0040] Thus, with the arrangement 1 according to the invention, surplus power can be extracted from the electricity grid 91 on a considerable scale and with high dynamics, and the corresponding energy can be stored in the form of hydrogen gas in the cavern 6. The previously required curtailment of wind turbines as a grid stabilization measure in such a case has thus become superfluous. The waste of otherwise available renewable energy associated with curtailment can thus be eliminated.

[0041] With the arrangement according to the invention, control power can be provided on a large scale. Thanks to the high dynamics, this can happen within seconds, so that even the provision of primary control power (seconds reserve) is possible. Reference is now made to Figure 2, which shows the types of control power resulting from the corresponding network operator guidelines and their temporal relationship. The number I represents the primary control power, which, as the so-called seconds reserve, must be provided completely within a period of 30 seconds. Typically, a period of up to 15 minutes has to be covered. The primary control power is followed by the secondary control power, which is shown in Figure 2 with the number II and can partially overlap with the primary control power I. This must be provided completely within a period of 5 minutes. Finally, this is followed by the so-calledMinute control power, which is indicated by number III in Figure 2 and must be fully provided after 15 minutes at the latest. Only long after that, in practice only after almost an hour, does the balancing via the balancing groups finally take effect, as shown by number IV in Figure 2.

[0042] It is understood that providing primary control power I requires high dynamics, while longer-term delivery, particularly of secondary control power and minute reserve power II, III, requires a large capacity in terms of the energy to be provided (power over time). The arrangement 1 according to the invention achieves both thanks to the gas generator 2 and CHP plant or fuel cell 31, both of which can be quickly controlled, as well as the cavern 6 with its large storage volume. The arrangement 1 according to the invention can thus provide all control powers I, II, and III. As a bonus, there is the further possibility of developing other applications with the stored hydrogen gas, for example to produce other energy sources such as methane or to use the hydrogen gas directly, be it as an additive in a (conventional) natural gas network or even in a pure hydrogen gas network.

[0043] To further increase the dynamic response in the provision of control power, a buffer accumulator 15 can also be provided. It is connected to the electrical side of both the gas generator 2, which is designed as an electrolyzer, and the fuel cell 31. It can thus quickly absorb or release power or power peaks, thus further ensuring a rapid response of the arrangement according to the invention.

[0044] Figure 3 shows a second embodiment of the arrangement according to the invention. Identical or similar components which have the same or a similar function are designated by the same reference number, and for a more detailed explanation thereof, reference is made to the above description. The second embodiment differs from the first embodiment shown in Figure 1 essentially in that a bypass line 7 is arranged between the filling line 51 and the extraction line 52. With this bypass line 7, the hydrogen gas generated by the gas generator 2 can be fed directly to the usage units 3, if necessary, in order to feed the methanation plant 33 there, for example, or to be fed directly into a hydrogen or natural gas network via the transfer point 35. The bypass line 7 is provided with a switchable shut-off valve 71 which blocks or opens the bypass line 7.It is connected via a signal line (not shown) to the control 8, which controls the shut-off valve 71 depending on the situational requirements of the arrangement 1 according to the invention and thus opens or closes the bypass line 7.

[0045] Figure 4 shows a third embodiment of the arrangement according to the invention. Identical or similar components which have the same or a similar function are designated by the same reference number, and for a more detailed explanation thereof, reference is made to the above description. The third embodiment differs from the second embodiment essentially in that the dual-directional line 5 with its filling line 51 and the separate withdrawal line 52 are arranged in a common pipe shaft 40 (and not each in a separate borehole as in the first and second embodiments).The fundamental advantages of the arrangement 1 according to the invention, namely being able to simultaneously feed hydrogen gas into the cavern 6 and thus provide negative control power to the electricity grid 91, and simultaneously extract hydrogen by means of the separate extraction line 52 for the usage units 3, for example in order to produce methane by means of the methanation plant 33, remain fully intact in this embodiment. Due to the arrangement of the.

[0046] However, by arranging the dual-directional line 5 in a common pipe shaft 40, the production of the pipe connection to the cavern 6 with the dual-directional line 5 is significantly simplified, which enables a more efficient production of the arrangement 1 according to the invention.

Claims

Patent claims: Arrangement for stabilizing an electricity grid (91) by means of an energy storage device, wherein the energy storage device comprises a gas generator (2) supplied by the electricity grid for a gaseous fuel, in particular hydrogen, and a cavern (6) with a connecting pipe (4) extending into the cavern (6), wherein, for storing energy, the gaseous fuel produced by the gas generator (2) is introduced into the cavern (6) via the connecting pipe (4) and, for storing energy, is extracted from the cavern (6), characterized in that the connecting pipe (4) is configured as a dual-directional line (5) extending into the cavern (6), which comprises a filling line (51) and a separate extraction line (52). Arrangement according to claim 1, characterized in that the dual-directional line (5) with its filling line (51) is configured for continuous injection, independent of extraction, and / or for continuous extraction, independent of injection.An arrangement according to claim 1 or 2, characterized in that several different usage units (3) for the gaseous fuel extracted from the cavern (6) are connected to the extraction line (52). An arrangement according to claim 3, characterized in that the different usage units (6) are connected to the extraction line (52) via at least one switchable gas diverter (30), wherein the extracted gaseous fuel is determined according to the switching state of the gas diverter (30). to one of the various usage units (3) .

5. Arrangement according to claim 4, characterized in that the gas diverter (30) is also designed to switch partial flows.

6. Arrangement according to claim 4 or 5, characterized in that the gas diverter (30) can also be switched during continuous withdrawal of the gaseous fuel.

7. Arrangement according to one of claims 4 to 6, characterized in that one of the usage units (3) is a device for reconverting the gas into electricity, in particular a fuel cell or combined heat and power plant (31) which generates electrical power and outputs it to a delivery line for connection to an electricity network (91) or a consumer.

8. Arrangement according to one of claims 4 to 7, characterized in that one of the usage units (3) is a methanization plant (33) which is designed to synthesize methane using hydrogen.

9. Arrangement according to one of claims 4 to 8, characterized in that one of the usage units (3) is a transfer point (35) to a gas network (93), in particular a natural gas network, for supplying the extracted gaseous fuel to the gas network (93).

10. Arrangement according to one of the preceding claims, characterized in that a control unit (8) for control power is provided, which has an input (80) for a signal for a target control power, in particular negative target control power, and which is configured to The gas generator (2) is controlled such that power corresponding to the target control power, in particular negative power, is drawn from the electricity grid (91) to produce the gaseous fuel that is stored in the cavern (6). The arrangement according to claim 10 is characterized in that the control unit (8) for control power further acts on a reconversion device (31) to feed additional power as positive control power into the electricity grid (91). The arrangement according to one of the preceding claims is characterized in that a switchable bypass line (7) is provided, which is connected between the gas generator (2) and the cavern (6) to the filling line (51) and connects the latter to the extraction line (52).An arrangement according to any one of the preceding claims, characterized in that a buffer accumulator (15) is provided, which is supplied by the electricity grid (91) connected to the gas generator (2) and is designed in particular for rapid supply, power output and / or power absorption. An arrangement according to any one of the preceding claims, characterized in that the filling line (51) and the extraction line (52) are spaced apart from each other and lead into the cavern (6). An arrangement according to any one of the preceding claims, characterized in that the filling line (51) and the extraction line (52) are arranged adjacent to each other. An arrangement according to the preceding claim, characterized in that the distance between the filling line (51) and the extraction line (52) is between three times, in particular at least ten times, and thirty times, in particular at most twenty times, their width, in particular diameter. An arrangement according to any of the preceding claims, characterized in that the filling line (51) and the extraction line (52) are guided into the cavern (6) in a common borehole (40). An arrangement according to any of the preceding claims, characterized in that the filling line (51) and the extraction line (52) extend at different depths into the cavern (6) with their respective outlets (53, 54), the filling line (51) preferably extending to a greater depth.Arrangement according to one of the preceding claims, characterized in that the cavern (6) is formed in a salt dome (90), and / or is designed for an operating pressure of at least 40 bar, preferably up to 200 bar.

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