DE102014101263B3 - Apparatus and method for storing energy using supercritical carbon dioxide - Google Patents

Abstract

The present invention relates to an apparatus for storing energy with the aid of supercritical carbon dioxide, comprising a pressure accumulator (12) for storing the carbon dioxide in the supercritical state, a feed line (14) for supplying the carbon dioxide to the pressure accumulator (12) with the feed line (14 ) cooperating compression assembly (18) for compressing the carbon dioxide to the supercritical state located upstream of the accumulator (12), a discharge conduit (24) for discharging the carbon dioxide from the accumulator (12), and cooperating with the evacuation conduit (24) A relaxation assembly (26) for venting the supercritical carbon dioxide disposed downstream of the accumulator (12). In addition, the invention relates to a corresponding method and a corresponding computer program.

Description

The present invention relates to an apparatus and method for storing energy by means of supercritical carbon dioxide. Due to the CO ₂ emissions generated by the combustion of fossil fuels for the provision of electrical energy, which are held responsible for global warming, and the finiteness of fossil fuels, the aim is to increase the share of renewable energy sources and one day the electric Obtain energy exclusively from renewable energy sources. Renewable energy sources are inexhaustible and do not produce CO ₂ . The best-known renewable energy sources are solar and wind energy. However, unlike fossil fuels, their availability is very uneven and unpredictable. The fact that there is no solar energy during the night is one of the few facts that can be predicted. However, whether the sun shines from a cloudless sky during the day or is obscured by clouds is extremely difficult to predict, especially in central and northern Europe. Although the likelihood of the sun shining from a cloudless sky is highest in the desert, solar energy can be used most effectively, but the main consumers are often very far away from the desert, so the electrical energy is very high must be transported, what a complex infrastructure is needed, which is not yet available. With the current infrastructure, high losses occur during transport, so it is not worthwhile to generate the electrical energy in the desert, for example in North Africa, and to transport it to northern Europe.

The situation is similar with the availability of wind energy. Windy areas are located near the coast or directly on the sea, but it is also true here that the main consumers often sit far away and the electrical energy has to be transported far, with the same disadvantages as in the use of solar energy occur.

Regardless of the drawbacks associated with the transport of electrical energy, the fluctuating availability of regenerative energy sources, exemplified by wind and solar energy, also directly results in a fluctuating feed of the electrical energy provided thereby. Thereby neither a low nor an oversupply is an advantage. In addition to a voltage drop in the event of a shortage, an oversupply represents a particular burden on the power grids, which is why in this case, wind turbines are throttled and solar power plants are disconnected from the grid. In order to respond to the fluctuating availability of renewable energy sources, energy storage systems are becoming increasingly important. A well-known example of an energy storage system is pumped storage power plants where, at times of low demand for electrical energy, water is pumped to a higher pool and drained in times of increased demand and the potential energy of the water in a water turbine is converted to electrical energy. The construction of pumped storage power plants, however, requires a massive intervention in nature, which is why such projects are hardly enforceable.

Another example of an energy storage system is compressed air storage power plants. This air is sucked in, compressed to about 70 bar and introduced into underground caverns, usually in salt domes, and stored there. If there is a great need for energy, the compressed air is expanded in a turbine and electrical energy is provided with a connected generator. Known compressed air storage power plants have a capacity of about 100 MW. At 70 bar, the temperature of air is above 600 ° C. The compressed air storage power plants currently in operation use diabile pressure accumulators, in which the heat generated during the compression of the air is partially dissipated, since the caverns are not designed for high temperatures. In addition, more heat is lost in the caverns. The lost heat is therefore no longer available for the supply of electrical energy, which is why this way of energy storage is not very efficient.

The heat loss can be reduced by passing the compressed air through a separate heat accumulator which absorbs some of the heat before the compressed air is stored in the caverns. These are adiabatic compressed air storage power plants. If electrical energy is required, the cold, compressed air is passed through the heat accumulator, heated and then added to the turbine, so that the heat energy is not or only slightly lost during storage. Adiabatic compressed air storage power plants are in the EP 2 530 283 A1 , of the US 2012/0305411 and the DE 10 2012 108 222 A1 described.

The high temperature of the compressed air to about 70 bar or more places high demands on the components and apparatus used in the compressed air storage power plants. As mentioned above, the temperature of air at these pressures is 600 ° C and more. Commonly used steel grades are no longer able to cope with these temperature loads, so that either alternative materials must be used or the apparatuses and components must be provided with internal insulation. These measures make the Design of compressed air storage power plants complicated and expensive and reduce the efficiency.

Object of the present invention is therefore to provide an apparatus and a method with which the disadvantages of pressure storage power plants described above can be met. In particular, a way should be created to use conventional materials without having to provide separate heat protection measures.

The object is achieved with devices according to claims 1 to 7, with the method according to claim 8 and with a computer program according to claim 9. Advantageous embodiments are the subject of the dependent claims.

In the DE 10 2006 035 272 A1 and the DE 10 2006 035 273 A1 For example, there is provided an apparatus for storing energy by means of supercritical carbon dioxide, comprising a pressure accumulator for storing the carbon dioxide in the supercritical state, a supply conduit for supplying the carbon dioxide to the accumulator, a compression arrangement cooperating with the supply conduit for compressing the carbon dioxide to the supercritical state upstream the pressure accumulator is arranged, a discharge line for discharging the carbon dioxide from the pressure accumulator, and a relaxation arrangement cooperating with the discharge line for releasing the supercritical carbon dioxide, which is arranged downstream of the pressure accumulator. An essential aspect of the teaching described therein is to use carbon dioxide (CO ₂ ) as the working medium instead of air. The critical point of CO ₂ is around 73.8 bar and 31 ° C. At higher pressures and temperatures, CO _{2 is} in the supercritical state, where no distinction can be made between the liquid and gaseous phases. In the supercritical state, the properties of CO _{2 are} between those of its gas and its liquid. CO ₂ is as dense as its liquid in the supercritical state, but has the viscosity of its gas. The essential aspect is that CO ₂ when compressed to 85 bar only has a temperature of about 400 ° C, which can be safely controlled with steel grades, which are commonly used for apparatus in power plant construction, without further action. Since no heat-protective measures have to be taken, the costs for the apparatus and components can be significantly reduced in comparison with compressed-air storage power plants that are operated with air. A certain exception is the expansion arrangement, which is usually performed as a turbine. As already stated, CO _{2 is} as dense as its liquid in the supercritical state, but has the viscosity of its gas. As a result, a special turbine design is necessary, with the CO ₂ can be relaxed in the supercritical state. Such turbines are for example in the US 2010/0024421 A1 described.

Due to the high density of CO ₂ , it also has a high energy storage density. As a result, the device can be operated economically even with smaller storage volumes, so that it is particularly suitable for the decentralized production of electrical energy. Calculated even with services of only one MW and for Entspeicherungszeiten of up to 10 hours and compression times of 14 and more hours to the day of an economic operation of the device. Usually, the need for electrical energy during the night is less than during the day, so that the device is preferably operated so that it is over-compacted at night and relaxed during the day and electrical energy is provided. However, the operating modes can also be changed several times between 0 and 24 hours if the price of electricity falls or rises unusually high. Since even smaller caverns suffice as pressure accumulators, the device offers itself as an ideal supplement for wind and solar energy or biogas plants.

The object is achieved by a device for storing energy with the aid of supercritical carbon dioxide, which comprises a first pressure accumulator for storing the carbon dioxide in the supercritical state, a first supply line for supplying the carbon dioxide to the first accumulator, a cooperating with the first supply line first compression arrangement for compacting the carbon dioxide to the supercritical state, a second accumulator for storing air, a second supply line for supplying the air to the second accumulator which passes through the first accumulator, a second compression arrangement cooperating with the second supply line for compressing the air, one with the second supply line cooperating heat exchanger, which is arranged in the first pressure accumulator and can be flowed through by the compressed air, for transferring heat from the compressed air to the carbon dioxide, a connecting line between the first and nd the second pressure accumulator for supplying carbon dioxide from the first pressure accumulator into the second pressure accumulator, a discharge line for discharging the carbon dioxide-air mixture from the second accumulator, and a relaxation arrangement cooperating with the discharge line for expanding the carbon dioxide-air mixture. The advantages that can be achieved with this second embodiment of the device according to the invention, correspond to those which have been described for the first embodiment. In addition, this embodiment still offers the following Another advantage: some of the heat that is generated when compressing the air is released to the CO ₂ . With the exception of the portion of the second supply line between the second compression arrangement and the heat exchanger, both the air and the CO ₂ temperatures of well below 600 ° C. Again, the equipment and components need not be made of a special material or provided with a special heat protection. The portion of the second supply line between the second compression arrangement and the heat exchanger makes up a small part of the device according to the invention and can be provided without significant effort with an inner insulation and / or cooling. In the second pressure accumulator is a carbon dioxide-air mixture in which CO _{2 has} its corresponding partial pressure and is not supercritical. Consequently, no special relaxation arrangement is needed which can relax CO ₂ in the supercritical state. On special turbines can be dispensed with, which significantly reduces the cost of providing the device according to the invention.

Preferably, the first pressure accumulator and / or the second accumulator are designed as a thermally insulating first and second pressure accumulator. As stated at the outset, smaller storage volumes are sufficient in order to operate the device according to the invention economically. The storage volume can be reduced so far that pressure vessels can be used. It is therefore no longer dependent on the presence of suitable underground caverns. Pressure vessels have a reduced risk of leakage, making them more reliable than caverns. In addition, the pressure vessel can alternatively be designed heat-insulated, so that heat losses can be minimized. Due to the reduced heat and pressure losses, the efficiency of the device according to the invention by the use of heat-insulated pressure vessels can be significantly increased.

It is preferred that in the first supply line, a first shut-off device is provided, with which the supply of carbon dioxide in the first pressure accumulator can optionally be interrupted or released. Accordingly, it is advantageous if in the second supply line, a second shut-off device is provided, with which the supply of air into the second pressure accumulator can optionally be interrupted or released. Moreover, it is particularly advantageous if a third shut-off device is provided in the connecting line, with which the supply of carbon dioxide from the first pressure accumulator in the second pressure accumulator can optionally be interrupted or released. It is particularly preferred if a fourth shut-off device is provided in the discharge line, with which the removal of the carbon dioxide-air mixture from the second pressure accumulator can optionally be interrupted or released. The shut-off devices make it possible to compress or to relax the CO ₂ depending on the energy requirement. The shut-off devices may be incorporated into a control system such that the compression or expansion process may be performed at an optimum time. In addition, the shut-off devices can be controlled so that there is always the same ratio of carbon dioxide to air in the second pressure accumulator, whereby the relaxation arrangement is operated and loaded uniformly, so that alternating stresses are reduced or largely avoided, which leads to an increase in the life.

• – Verdichten des Kohlendioxids auf den überkritischen Zustand mittels der ersten Verdichtungsanordnung und Zuführen des verdichteten Kohlendioxids in den ersten Druckspeicher mittels der ersten Zuführleitung,
• – Verdichten der Luft mittels der zweiten Verdichtungsanordnung und Zuführen der verdichteten Luft in den zweiten Druckspeicher mittels der zweiten Zuführleitung,
• – Übertragen von Wärme von der verdichteten Luft auf das Kohlendioxid mittels des Wärmetauschers im ersten Druckspeicher,
• – Zuführen von Kohlendioxid vom ersten Druckspeicher in den zweiten Druckspeicher,
• – Abführen des Kohlendioxid-Luft-Gemisches aus dem zweiten Druckspeicher mittels der Abführleitung, und
• – Entspannen des Kohlendioxid-Luft-Gemisches mittels der Entspannungsanordnung.

The object is further achieved by a method for storing energy with the aid of supercritical carbon dioxide with a device according to the third embodiment, which comprises the following steps:

• Compressing the carbon dioxide to the supercritical state by means of the first compression arrangement and feeding the compressed carbon dioxide into the first pressure accumulator by means of the first supply line,
• - Compressing the air by means of the second compression arrangement and supplying the compressed air in the second pressure accumulator by means of the second supply line,
• Transferring heat from the compressed air to the carbon dioxide by means of the heat exchanger in the first pressure accumulator,
• Supplying carbon dioxide from the first pressure reservoir into the second pressure reservoir,
• - Discharge of the carbon dioxide-air mixture from the second pressure accumulator by means of the discharge line, and
• - Relaxing of the carbon dioxide-air mixture by means of the relaxation arrangement.

The advantages that can be achieved with the method again correspond to those that have been discussed for the device according to the embodiment described above. Since a carbon dioxide-air mixture is expanded, no relaxation arrangement is required, which is designed for the relaxation of supercritical CO ₂ . Furthermore, lower storage volumes are sufficient to operate the device economically. The decentralized operation of the device according to the invention is economically possible.

• – Verdichten des Kohlendioxids auf den überkritischen Zustand mittels der ersten Verdichtungsanordnung und Zuführen des verdichteten Kohlendioxids in den ersten Druckspeicher mittels der ersten Zuführleitung,
• – Verdichten der Luft mittels der zweiten Verdichtungsanordnung und Zuführen der verdichteten Luft in den zweiten Druckspeicher mittels der zweiten Zuführleitung,
• – Übertragen von Wärme von der verdichteten Luft auf das Kohlendioxid mittels des Wärmetauschers im ersten Druckspeicher,
• – Zuführen von Kohlendioxid vom ersten Druckspeicher in den zweiten Druckspeicher,
• – Abführen des Kohlendioxid-Luft-Gemisches aus dem zweiten Druckspeicher mittels der Abführleitung, und
• – Entspannen des Kohlendioxid-Luft-Gemisches mittels der Entspannungsanordnung.

The invention further relates to a computer program for carrying out a method for storing energy with the aid of supercritical carbon dioxide with a device according to one of the aforementioned embodiments with program means for causing a computer to perform the following steps when the computer program is executed on the computer:

• Compressing the carbon dioxide to the supercritical state by means of the first compression arrangement and feeding the compressed carbon dioxide into the first pressure accumulator by means of the first supply line,
• - Compressing the air by means of the second compression arrangement and supplying the compressed air in the second pressure accumulator by means of the second supply line,
• Transferring heat from the compressed air to the carbon dioxide by means of the heat exchanger in the first pressure accumulator,
• Supplying carbon dioxide from the first pressure reservoir into the second pressure reservoir,
• - Discharge of the carbon dioxide-air mixture from the second pressure accumulator by means of the discharge line, and
• - Relaxing of the carbon dioxide-air mixture by means of the relaxation arrangement.

The advantages and technical effects which can be achieved with the computer program correspond to those which have been set forth for the method according to the invention and the device according to the invention.

The invention will be explained in detail by means of preferred embodiments with reference to the attached drawings. Show it

1 a first embodiment of a device according to the invention,

2 a second embodiment of the device according to the invention, and

3 a third embodiment of the device according to the invention, each with reference to a schematic diagram.

1 shows a first embodiment of a device 10 ₁ for storing energy with the help of supercritical carbon dioxide. The device 10 ₁ includes a pressure accumulator 12 in the illustrated embodiment as an isolated pressure vessel 13 is executed. Furthermore, the device comprises 10 ₁ a supply line 14 , with which carbon dioxide the pressure accumulator 12 can be supplied in a reservoir 16 kept at atmospheric pressure. In the supply line 14 is a compacting arrangement 18 between the reservoir 16 and the accumulator 12 arranged, which in the example shown two compressors in series 20 includes. The compacting arrangement 18 serves to get that from the reservoir 16 taken CO ₂ from the atmospheric pressure to compress that it is supercritical. The compressors 20 are driven by a motor, not shown. Between the compaction arrangement 18 and the accumulator 12 is a first shut-off device 22 provided, with which the supply line 14 optionally can be locked or released.

In addition, the device includes 10 ₁ a discharge line 24 , about which the carbon dioxide from the accumulator 12 dissipated and a relaxation arrangement 26 can be supplied. The relaxation arrangement 26 includes two turbines 28 , which are connected to a generator, not shown, with which in the relaxation in the turbine 28 generated kinetic energy is converted into electrical energy. Between the relaxation arrangement 26 and the accumulator 12 there is a second shut-off device 30 with which the discharge line 24 optionally can be locked or released. In the example shown, the supply line 14 and the discharge line 24 to a circulation line 32 summarized.

In operation of the device 10 ₁ becomes the CO ₂ from the reservoir 16 in the circulation line 32 initiated, including a three-way valve 34 is switched accordingly. The CO ₂ is in the compression arrangement 18 compressed in about to a pressure of 85 bar, in which it has a temperature of about 400 ° C and is in the supercritical state. Over the open first shut-off device 22 is the compressed and supercritical CO ₂ in the isolated pressure vessel 13 initiated, wherein the second shut-off device 30 closed is. This process is continued until the pressure vessel 13 is filled. Subsequently, the three-way valve 34 switched so that the circulation line 32 closed is. By opening the second shut-off device 30 Now CO ₂ can be cycled. The compressed supercritical CO ₂ is in the expansion arrangement 26 relaxed, wherein the resulting kinetic energy in the generator, not shown, converted into electrical energy. The relaxed CO ₂ is then returned to the reservoir 16 and at a predetermined time in the compression arrangement 18 where it is compressed again.

Turbines are usually designed so that they can be operated optimally in a certain pressure range. As the pressure of the pressure vessel 13 As CO ₂ effluent decreases over time, multiple turbines may be provided to respond to the changing pressure. In the example shown, a high and a low pressure turbine are provided, which are connected in series are, but which can also be connected in parallel.

Because the device 10 ₁ can only be operated economically if the compression process is carried out in periods, if the electrical energy is available at low cost, and the relaxation process is carried out when the electrical energy is expensive, the two processes will never be carried out simultaneously, even if this would be technically possible. Consequently, the expansion process can be stopped and the compression process can be initiated when the demand for electrical energy decreases and the electrical energy for driving the compression arrangement 18 is available inexpensively. Conversely, if the demand for electrical energy increases, the compression process can be stopped and the expansion process started. In order to be able to carry out the two processes at different times despite the recycling of the carbon dioxide, the CO ₂ reservoir must be 16 be big enough. Alternatively, another storage tank in the circulation line 32 be provided, which is not shown here.

The first and the second shut-off device 22 . 30 each have an adjustment unit 36 with which the shut-off devices 22 . 30 can be opened or closed remotely on the initiative of a control or regulation system, not shown. The same applies analogously for the three-way valve 34 ,

In 2 is a second embodiment 10 _{2 of} the device shown. In this embodiment, the CO _{2 is} not circulated, but from the reservoir 16 removed, subjected to the process described above and then released to the environment. The CO ₂ can be collected and reused in a manner not shown. Incidentally, the device is the same 10 ₂ according to the second embodiment of the first embodiment.

In 3 is an embodiment of the device according to the invention 10 ₃ for storing energy by means of supercritical carbon dioxide illustrated by a schematic diagram. The device 10 ₃ according to the second embodiment comprises a first pressure accumulator 40 for storing the supercritical carbon dioxide and a second pressure accumulator 42 for storing compressed air. As in the first embodiment, the CO _{2 is} in the reservoir 16 held and via a first supply line 46 to the first accumulator 40 performed as a thermally insulated first pressure vessel 48 is executed. In the first supply line 46 is a first compacting arrangement 50 provided, which in the example shown a compressor 52 includes. But there can also be several compressors 52 be provided, which are driven by a motor, not shown. In the first compression arrangement 50 the CO _{2 is} compressed to such an extent that it is in the supercritical state. The pressure is about 85 bar. Between the first compaction arrangement 50 and the first pressure vessel 48 is a first shut-off device 54 arranged, with which the first supply line 46 and thus the access to the first accumulator 40 optionally opened and locked.

Furthermore, a second compression arrangement 56 provided, with which the air sucked from the environment also compressed to about 85 bar and a second supply line 58 the second pressure accumulator 42 as an isolated second pressure vessel 57 executed, is supplied. Between the second compression arrangement 56 and the second pressure accumulator 42 is a second shut-off device 59 provided with which the second supply line 58 can optionally be opened and closed. As mentioned above, the air heats up very strongly in such a compression. The second supply line 58 acts with a heat exchanger 60 together, in the first accumulator 12 is arranged. The heat of the air, which is the heat exchanger 60 flows through, is on the first pressure accumulator 40 transferred CO ₂ , so that both in the first and in the second pressure vessel 48 . 57 a temperature of well below 600 ° C is present. In the section of the second supply line 58 that is between the second compacting arrangement 56 and the heat exchanger 60 is located, has a very high temperature. This section may be wholly or partially provided with internal insulation or cooling to the material of this section of the second supply line 58 to protect against thermal stress.

The first and the second accumulator 40 . 42 are by means of a connecting line 62 connected with each other. The connection line 62 can with a third shut-off device 64 optionally open and closed.

From the second pressure vessel 57 leads a discharge line 65 to a relaxation arrangement 66 , which relaxes the air or the carbon dioxide-air mixture and thus electrical energy can be provided via a generator, not shown. In the example shown, the relaxation arrangement comprises 66 a turbine 68 , where also several series or parallel connected turbines 68 can be provided. Between the second pressure vessel 57 and the relaxation arrangement 66 is a fourth shut-off device 70 arranged.

In operation, first the CO ₂ from the reservoir 16 the first compaction arrangement 50 fed and compressed there so far that it is supercritical (about 85 bar). Over the open first shut-off device 54 is the supercritical CO ₂ in the first pressure vessel 48 initiated until it is filled. As soon as the first pressure vessel 48 is filled, air is sucked from the environment and by means of the second compression arrangement 56 compressed to about 85 bar. The compressed air is via the second supply line 58 in the second pressure vessel 57 passed, wherein in the second supply line 58 arranged second shut-off device 59 is open. Because the air when feeding into the second pressure vessel 57 the heat exchanger 60 that is in the first pressure vessel 48 heat is transferred from the air to the CO ₂ . To prevent the CO ₂ over the connecting line 62 from the first pressure vessel 48 in the second pressure vessel 57 is flowing, that is in the connecting line 62 arranged third shut-off device 64 closed as long as that the second pressure vessel 57 completely filled. The fourth shut-off device 70 is closed.

Are both pressure vessels 48 . 57 completely filled, become the first and the second shut-off device 54 . 59 closed and the third and fourth shut-off device 64 . 70 open. The compressed air flows out of the second pressure vessel 57 and will be in the relaxation arrangement 66 relaxed, so that there is provided by means of a generator, not shown electrical energy. As the air escapes, the pressure in the second pressure vessel drops 57 so that the supercritical CO ₂ from the first pressure vessel 48 in the second pressure vessel 57 over the connecting line 62 nachströmt. In the second pressure accumulator 57 is a carbon dioxide-air mixture in which CO _{2 has} its corresponding partial pressure and is not supercritical. The carbon dioxide-air mixture is in the relaxation arrangement 66 relaxed and then released to the environment. The turbine 68 does not need to be designed for supercritical fluid conditions. The carbon dioxide-air mixture can also be collected and fractionated again into carbon dioxide and air.

As already with respect to the device 10 ₁ executed according to the first embodiment, the shut-off devices 54 . 59 . 64 . 70 each with an adjustment 36 provided so that the shut-off devices 54 . 59 . 64 . 70 can be integrated into a control or regulating circuit, not shown, and opened or closed by a control or regulation system, also not shown, which is operated with a computer program according to the invention. This control system can respond to fluctuations in the power grid and compressed in an over supply of air and / or carbon dioxide targeted and relax in a deficiency the compressed air and / or the carbon dioxide-air mixture. Thus, it is possible to react quickly to the fluctuating availability of the regenerative energy sources and to contribute to the security of supply with electrical energy and to the stability of the power grids.

LIST OF REFERENCE NUMBERS

10, 10 ₁ , 10 ₂ , 10 ₃

 contraption

12

 accumulator

13

 pressure vessel

14

 feed

16

 reservoir

18

 A compression device

20

 compressor

22

 first shut-off device

24

 discharge

26

 relaxation arrangement

28

 turbine

30

 second shut-off device

32

 Circuit line

34

 Three-way valve

36

 adjustment

40

 first accumulator

42

 second pressure accumulator

46

 first supply line

48

 first pressure vessel

50

 first compacting arrangement

52

 compressor

54

 first shut-off device

56

 second compression arrangement

57

 second pressure vessel

58

 second supply line

59

 second shut-off device

60

 heat exchangers

62

 connecting line

64

 third shut-off device

65

 discharge

66

 relaxation arrangement

68

 turbine

70

 fourth shut-off device

Claims (9)

Device for storing energy with the aid of supercritical carbon dioxide, comprising - a first accumulator ( 40 ) for storing the carbon dioxide in the supercritical state, - a first supply line ( 46 ) for supplying the carbon dioxide to the first pressure accumulator ( 12 ), - one with the first supply line ( 46 ) cooperating first compaction arrangement ( 50 ) for compressing the carbon dioxide to the supercritical state, - a second pressure accumulator ( 42 ) for storing air, - a second supply line ( 58 ) for supplying the air to the second accumulator ( 43 ), which the first pressure accumulator ( 40 ), - one with the second supply line ( 58 ) cooperating second compression arrangement ( 56 ) for compressing the air, - one with the second supply line ( 58 ) cooperating heat exchanger ( 60 ), in the first pressure accumulator ( 40 ) and can be flowed through by the compressed air, for transferring heat from the compressed air to the carbon dioxide, - a connecting line ( 62 ) between the first and the second pressure accumulator ( 40 . 42 ) for supplying carbon dioxide from the first pressure accumulator ( 40 ) in the second pressure accumulator ( 42 ), - a discharge line ( 65 ) for discharging the carbon dioxide-air mixture from the second pressure accumulator ( 42 ), and - one with the discharge line ( 65 ) cooperating relaxation arrangement ( 66 ) to relax the carbon dioxide-air mixture. Apparatus according to claim 1, characterized in that the first pressure accumulator ( 40 ) as a thermally insulated first pressure vessel ( 48 ) is executed. Device according to one of claims 1 or 2, characterized in that the second pressure accumulator ( 42 ) as a thermally insulated second pressure vessel ( 57 ) is executed. Device according to one of claims 1 to 3, characterized in that in the first supply line ( 46 ) a first shut-off device ( 54 ) is provided, with which the supply of carbon dioxide in the first pressure accumulator ( 40 ) can optionally be interrupted or released. Device according to one of claims 1 to 4, characterized in that in the second supply line ( 58 ) a second shut-off device ( 59 ) is provided, with which the supply of air into the second pressure accumulator ( 42 ) can optionally be interrupted or released. Device according to one of claims 1 to 5, characterized in that in the connecting line ( 62 ) a third shut-off device ( 64 ) is provided, with which the supply of carbon dioxide from the first pressure accumulator ( 40 ) in the second pressure accumulator ( 42 ) can optionally be interrupted or released. Device according to one of claims 1 to 6, characterized in that in the discharge line ( 65 ) a fourth shut-off device ( 70 ) is provided, with which the removal of the carbon dioxide-air mixture from the second pressure accumulator ( 42 ) can optionally be interrupted or released. A method of storing supercritical carbon dioxide energy with an apparatus according to any one of claims 1 to 7, comprising the steps of: - compressing the carbon dioxide to the supercritical state by means of a first compacting arrangement ( 50 ) and feeding the compressed carbon dioxide into the first pressure accumulator ( 40 ) by means of the first supply line ( 46 ), - compressing the air by means of a second compression arrangement ( 56 ) and feeding the compressed air into the second pressure accumulator ( 42 ) by means of the second supply line ( 58 ), - transfer of heat from the compressed air to the carbon dioxide by means of the heat exchanger in the first pressure accumulator ( 40 ), - supplying carbon dioxide from the first accumulator ( 40 ) in the second pressure accumulator ( 42 ), - discharging the carbon dioxide-air mixture from the second pressure accumulator ( 42 ) by means of the discharge line ( 65 ), and - Relaxing of the carbon dioxide-air mixture by means of the expansion arrangement ( 66 ). A computer program for carrying out a method of storing supercritical carbon dioxide energy with an apparatus according to any one of claims 1 to 7, comprising program means for causing a computer to perform the following steps when the computer program is executed on the computer: - compressing the carbon dioxide the supercritical state by means of a first compaction arrangement ( 50 ) and feeding the compressed carbon dioxide into the first pressure accumulator ( 40 ) by means of the first supply line ( 46 ), - compressing the air by means of a second compression arrangement ( 56 ) and feeding the compressed air into the second pressure accumulator ( 42 ) by means of the second supply line ( 58 ), - transfer of heat from the compressed air to the carbon dioxide by means of the heat exchanger in the first pressure accumulator ( 40 ), - supplying carbon dioxide from the first accumulator ( 40 ) in the second pressure accumulator ( 42 ), - discharging the carbon dioxide-air mixture from the second pressure accumulator ( 42 ) by means of the discharge line ( 65 ), and - relaxing the carbon dioxide-air mixture by means of the expansion arrangement ( 66 ).

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