Facility and method for energy management

Abstract

The invention provides a facility and a method for energy management. The method comprises a gas meter (2) for storing carbon dioxide in a gas phase and at a first storage pressure (PAG ') balanced with atmospheric pressure and a gas meter (3) for storing carbon dioxide in a liquid phase, between the mass accumulators (11) of carbon dioxide at the second storage pressure (PA 'H), a closed thermodynamic cycle conversion (TTC) is carried out first in one direction in the charging phase and then in the opposite direction in the discharging phase. In a charging phase, it is arranged to remove heat from the mass accumulator (11) to condense a portion of the vapour phase of carbon dioxide contained in the mass accumulator (11) and to maintain the second storage pressure (PA 'H) constant or substantially constant. In a discharge phase, it is arranged to transfer heat to the mass accumulator (11) in order to vaporize a portion of the liquid phase of carbon dioxide contained in the mass accumulator (11) and to maintain the second storage pressure (PA 'H) constant or substantially constant.

Description

TECHNICAL FIELD

[0001] The object of the present invention is a plant and a method for energy management, where management aims at absorbing, storing, converting and producing energy.

[0002] More precisely, the object of the present invention is a system able to absorb / use energy, able to keep the stored energy over time and able to convert the stored energy back into usable energy, for example electrical, thermal, mechanical energy.

[0003] The present invention can for example be in the context of systems for the production of electricity from various sources and medium and large energy storage, typically with power from hundreds of kW up to tens of MW (for example 20-25 MW), but also hundreds of MW, and with storage capacity from hundreds of kWh up to hundreds of MWh and also up to several GWh, for both land and marine applications. The present invention can also be in the field of systems for the production of electricity from various sources and small energy storage, typically with power from a few kW up to hundreds of kW and with storage capacity from a few kWh up to hundreds of kWh, for domestic as well as commercial applications both on land and at sea.

[0004] DEFINITIONS

[0005] In the present description and in the appended claims, reference will be made to the following definitions.

[0006] Cyclic thermodynamic conversion (TTC): thermodynamic conversion from point A to point B and from point B to point A, not necessarily passing through the same intermediate points; the TTC works between two mass accumulations of working fluid, one initial and the other final.

[0007] Thermodynamic cycle (CT): thermodynamic conversion from point X to point Y, where X coincides with Y; unlike the above-mentioned cyclic thermodynamic conversion (TTC), the thermodynamic cycle (CT) does not have, within the cycle, a mass accumulation of working fluid significant for energy purposes.

[0008] Closed CT and / or TTC: no mass exchange with the atmosphere (significant for energy purposes).

[0009] Open CT and / or TTC: mass exchange with the atmosphere (significant for energy purposes).

[0010] Slightly overpressure: pressure higher than atmospheric pressure, where the pressure difference with respect to atmospheric pressure is from a few millibars up to a few tens of millibars, for example from 3-4 millibars to 70-80 millibars. BACKGROUND

[0011] The publication WO2020 / 039416, representative of the same applicant, shows a method and a plant for energy storage. The plant comprises: a casing for storing a working fluid in gaseous phase and in pressure equilibrium with the atmosphere, other than atmospheric air; a reservoir for storing such working fluid in liquid or supercritical phase, having a temperature close to the critical temperature, wherein the critical temperature is close to the ambient temperature. The plant is configured to perform a closed cycle thermodynamic conversion first in a storage configuration in one direction and then in a discharge configuration in the opposite direction, between the casing and the reservoir. In the storage configuration, the plant accumulates heat and pressure, while in the discharge configuration, the plant generates energy.

[0012] Furthermore, all the documents WO2021 / 165809, WO2021 / 191786 and WO2022 / 101727, representative of the same applicant, show plants based on the same principle shown in WO2020 / 039416 (closed cycle thermodynamic conversion between two accumulations of mass). SUMMARY

[0013] The Applicant has noted that it is possible to further improve the above-mentioned method and plant in the documents WO / 2020 / 039416, WO2021 / 165809, WO2021 / 191786 and WO2022 / 101727, in particular with reference to the optimization of the method and the simplicity of the plant construction.

[0014] The Applicant has noted in particular that plants and methods, such as the above-mentioned plants and methods which operate in the supercritical field, i.e. plants and methods configured to operate the supercritical conversion of a working fluid and to accumulate said working fluid at high pressure in a reservoir in supercritical phase, present criticality in terms of complexity and costs of the storage system. In fact, for example, WO / 2020 / 039416 shows the use of a variable volume chamber and a compensation circuit to be able to store the working fluid in supercritical phase and to maintain a substantially constant pressure in the working fluid in supercritical phase.

[0015] The Applicant therefore aims to conceive and realize a system similar to the one shown in WO / 2020 / 039416, operating by means of the cycle and supercritical thermodynamic conversion (TTC) of a working fluid, which allows to store the working fluid more easily and effectively in a high pressure storage device.

[0016] The Applicant also aims more generally to realize a supercritical TTC type system (plant and method) for the absorption, storage (energy storage), conversion and production of energy, so as to allow managing (absorbing, storing, converting, producing, classifying) energy from various sources (such as non-renewable sources and fuels, such as fossil fuels, and renewable and synthetic sources and fuels) in a flexible, efficient and effective way.

[0017] The Applicant has found that the above indicated purposes can be achieved by adopting a technical solution which allows operating under supercritical conditions but storing the working fluid in a high pressure reservoir under subcritical conditions.

[0018] In particular, the indicated purposes and others are substantially achieved by a plant and method for the management (absorption, storage, conversion, production) of energy of the type claimed in the appended claims and / or described in the following aspects.

[0019] In a first independent aspect, the present invention relates to a plant for energy management, the plant comprising: a working fluid other than atmospheric air; a gasometer which internally delimits a variable volume containing or configured to contain the working fluid in gaseous phase and at a first storage pressure (PAG') constant and equal to atmospheric pressure or slightly overpressure with respect to atmospheric pressure; a compressor fluidically connected with the gasometer; an expander fluidically connected with the gasometer; a thermal accumulator fluidically connected with the compressor and with the expander and configured to exchange heat with the working fluid; a mass accumulator which internally delimits a constant volume containing or configured to contain the working fluid in liquid phase at a second storage pressure (PA'H), the mass accumulator being fluidically connected with the thermal accumulator; a pressure reduction device which operatively acts between the thermal accumulator and the mass accumulator; a pump which operatively acts between the thermal accumulator and the mass accumulator; a heat exchange device operatively coupled to the mass accumulator and configured to exchange heat with the working fluid present in the mass accumulator; a line and control device configured to operate the plant in a charging configuration and in a discharge configuration.

[0020] In the charging configuration, the working fluid is delivered from the gas meter to the mass accumulator through the compressor, the thermal accumulator and the pressure reduction device and is accumulated in the mass accumulator; the compressor compresses the working fluid to a final compression pressure (PC; PC2) higher than the critical pressure (Pcr) of the working fluid, the thermal accumulator absorbs heat from the working fluid and cools said working fluid to a final cooling temperature (TE) close to the critical temperature (Tcr) of the working fluid, preferably lower or slightly higher than the critical temperature (Tcr) of the working fluid; the pressure reduction device reduces the pressure of the working fluid to a reduced pressure (PG) lower than the critical pressure (Pcr) of said working fluid; the working fluid is accumulated in the mass accumulator at a second storage pressure (PA'H) lower than the critical pressure (Pcr) of the working fluid and in vapor phase equilibrium with itself. In the charging configuration, the heat exchange device removes heat from the mass accumulator to condense a portion of the vapor phase of the working fluid contained in the mass accumulator and keeps the second storage pressure (PA'H) in said mass accumulator constant or substantially constant.

[0021] In the discharge configuration, the working fluid is delivered from the mass accumulator to the gas meter through the pump, the thermal accumulator and the expander and is accumulated in the gas meter; the pump pumps the working fluid at a discharge pressure (PC') higher than the critical pressure (Pcr) of the working fluid, the thermal accumulator transfers heat previously accumulated to the working fluid and heats said working fluid, the expander expands the working fluid and the working fluid is accumulated in the gas meter at a first storage pressure (PAG'). In the discharge configuration, the heat exchange device transfers heat to the mass accumulator to vaporize a portion of the liquid phase of the working fluid contained in the mass accumulator and keeps the second storage pressure (PA'H) in said mass accumulator constant or substantially constant.

[0022] In a second independent aspect, the present application relates to a method for energy management, the method comprising: performing a closed cycle thermodynamic conversion (TTC) first in a charging phase in one direction and then in a discharge phase in the opposite direction between a gas meter for storing a working fluid in gaseous phase and at a first storage pressure (PAG') in equilibrium with atmospheric pressure and a mass accumulator for storing said working fluid in liquid phase at a second storage pressure (PA'H); wherein, in the charging phase, the method stores heat and pressure and, in the discharge phase, the method produces energy using the heat and pressure previously stored.

[0023] In the charging phase, the method comprises: compressing the working fluid to a final compression pressure (PC; PC2) higher than the critical pressure (Pcr) of the working fluid, cooling the working fluid to a final cooling temperature (TE) close to the critical temperature (Tcr) of the working fluid by storing the heat removed from the working fluid, reducing the pressure of the working fluid to a reduced pressure (PG) lower than the critical pressure (Pcr) of the working fluid, storing the working fluid in the mass accumulator at a second storage pressure (PA’H) lower than the critical pressure (Pcr) of the working fluid and in equilibrium with the vapour phase of the working fluid itself; wherein, in the charging phase, the method further comprises: removing heat from the mass accumulator to condense a portion of the vapour phase of the working fluid contained in the mass accumulator and keeping the second storage pressure (PA’H) in the mass accumulator constant or substantially constant. Preferably, the final cooling temperature (TE) is lower than or slightly higher than the critical temperature (Tcr) of the working fluid.

[0024] In the discharge phase, the method comprises: pumping the working fluid at a discharge pressure (PC’) higher than the critical pressure (PC’) of the working fluid, transferring the heat previously accumulated to the working fluid and heating the working fluid, expanding the working fluid and storing the working fluid in the gasometer at a first storage pressure (PAG’); wherein, in the discharge phase, the method further comprises: transferring heat to the mass accumulator to vaporise a portion of the liquid phase of the working fluid contained in the mass accumulator and keeping the second storage pressure (PA’H) in the mass accumulator constant or substantially constant.

[0025] In the charging phase / configuration, in order to keep the pressure in the mass accumulator constant or substantially constant, if the expansion ends within the Andrews bell-shaped graph, the increase in the volume occupied by the working fluid stored in the liquid phase (i.e. the decrease in the volume occupied by the working fluid vapour) is compensated for by condensing all or part of the vapour of the working fluid already contained in the mass accumulator and possibly generated during the pressure reduction.

[0026] In the discharge phase / configuration, in order to keep the pressure in the mass accumulator constant or substantially constant, the decrease in the volume of the working fluid in the liquid phase (i.e. the increase in the volume occupied by the working fluid vapour) is compensated for by vaporising a portion of the liquid of the working fluid, otherwise the system would be depressurised and cooled.

[0027] The facility of the first aspect is configured to perform the method of the second aspect and / or a method as defined in one or more of the following aspects. The method of the second aspect can be performed via the apparatus of the first aspect and / or via a facility as defined in one or more of the following aspects.

[0028] The Applicant has verified that the facility and the method according to the present application allow to obtain the predetermined purposes.

[0029] The Applicant has verified that the plant and the method according to the present application allow to perform a supercritical conversion and at the same time store the working fluid in the mass accumulator under subcritical conditions and in a liquid phase in equilibrium with its own limited vapor phase (two-phase mass accumulator under subcritical conditions). In fact, in the internal volume of the mass accumulator, there is not any separation membrane between the liquid phase and the vapor phase of the working fluid.

[0030] In particular, the Applicant has verified that the heat exchange device allows to remove heat from the mass accumulator in an amount equal to the condensation latent heat of the portion of vapor initially contained in the mass accumulator which must condense to allow the accumulation of the liquid without pressure increase or with a controlled pressure increase. Then, the heat exchange device allows to keep constant or substantially constant the second storage pressure in the mass accumulator.

[0031] Other aspects of the present application are listed below.

[0032] In an aspect, the expander is coupled to an electric generator.

[0033] In an aspect, the compressor is coupled to an electric motor.

[0034] In an aspect, the working fluid is carbon dioxide (CO2) or comprises carbon dioxide (CO2) or is a mixture comprising carbon dioxide as main component. Alternatively, the working fluid is selected from the group comprising: a mixture of carbon dioxide (CO2) and other substances (to correct the critical temperature of the working fluid), SF6, N2O or mixtures thereof.

[0035] In an aspect, the ratio between the second storage pressure (PA'H) of the working fluid and the critical pressure (Pcr) is between 0.2 and 0.99, preferably between 0.4 and 0.95.

[0036] In an aspect, the ratio between the final compression pressure (PC; PC2) of the working fluid and the critical pressure (Pcr) is between 1.01 and 10.0, preferably between 1.05 and 2.5.

[0037] In an aspect, the ratio between the final cooling pressure (PE) of the working fluid and the critical pressure (Pcr) is between 1.01 and 10.0, preferably between 1.05 and 2.5.

[0038] In an aspect, the ratio between the reduction pressure (PG) of the working fluid and the critical pressure (Pcr) is between 0.01 and 0.99, preferably between 0.4 and 0.9. The reduction pressure (PG) corresponds to the second storage pressure (PA'H) or is only slightly different from the second storage pressure (PA'H), for example by a few bars (for example from 1 bar to 5 bars).

[0039] In an aspect, the ratio between the final cooling temperature (TE) in Kelvin and the critical temperature (Tcr) in Kelvin is between 0.4 and 1.1, preferably between 0.75 and 0.95.

[0040] In an aspect, if the working fluid is carbon dioxide (CO2), the second storage pressure (PA'H) is between 20 and 70 bars, optionally between 40 and 60 bars.

[0041] In an aspect, the liquid / vapor separator is operatively arranged between the pressure reduction device and the mass accumulator.

[0042] In an aspect, the refrigerator is operatively arranged between the thermal accumulator and the pressure reduction device. In the charging configuration of the plant, the refrigerator is configured to remove heat from the working fluid entering the pressure reduction device so as to reduce and / or eliminate the vapor quality of said working fluid at the outlet of the pressure reduction device.

[0043] In an aspect, after cooling the working fluid to a final cooling temperature (TE) close to the critical temperature (Tcr) and before reducing the pressure of the working fluid to a reduced pressure (PG), heat is removed from the working fluid, optionally via the refrigerator of the preceding aspect, so as to reduce and / or eliminate the vapor quality of said working fluid at the end of the pressure reduction.

[0044] In an aspect, the pressure reduction device comprises a pressure let-down valve.

[0045] In an aspect, during the charging phase, reducing the pressure of the working fluid comprises pressure let-down of the working fluid, optionally via the pressure let-down valve of the preceding aspect.

[0046] In an aspect, the refrigerator is configured to remove heat from the working fluid entering the pressure reduction device, i.e. in the pressure let-down valve, so that the final pressure let-down temperature (TG) of the working fluid exiting said pressure reduction device, i.e. from the pressure let-down valve, is lower than the saturation temperature of said working fluid at the reduced pressure (PG) corresponding to or slightly different from the second storage pressure (PA'H).

[0047] In an aspect, removing heat from the working fluid so as to reduce and / or eliminate the vapor quality of said working fluid at the end of the pressure reduction comprises bringing the working fluid to a final pressure let-down temperature (TG) at the end of the pressure reduction, which is lower than the saturation temperature of said working fluid at the reduced pressure (PG) corresponding to or slightly different from the second storage pressure (PA'H).

[0048] The final temperature of the depressurization (TG) is such that the working fluid at the discharge of the depressurization device results in sub-cooling, with the advantage of not adding steam to be condensed in the mass accumulator. By sub-cooling, it is possible to partially or completely condense the vapour portion of the working fluid contained in the mass accumulator at the beginning of the charging phase, thus ensuring a constant or very small variation of the pressure in the mass accumulator during the charging phase, and reducing or completely eliminating the heat subtracted from the system during the charging phase.

[0049] In an alternative aspect, the depressurization device comprises an auxiliary expander, for example an auxiliary turbine.

[0050] In an aspect, the auxiliary expander is capable of extracting energy and converting it into mechanical and / or electrical energy.

[0051] In an aspect, the auxiliary expander is coupled to an auxiliary generator.

[0052] In an aspect, the auxiliary expander is an impulse type auxiliary expander, and in particular a Bently turbine.

[0053] In an aspect, during the charging phase, reducing the pressure of the working fluid comprises subjecting the working fluid to an auxiliary expansion, optionally via the auxiliary expander of the preceding aspect.

[0054] In an aspect, the refrigeration machine is configured to remove heat from the working fluid entering the auxiliary expander, so that the working fluid remains in a sub-cooled liquid state at the outlet of said auxiliary expander.

[0055] In an aspect, removing heat from the working fluid so as to reduce and / or eliminate the vapour dryness of said working fluid at the end of the depressurization comprises removing heat from the working fluid before the auxiliary expansion, so that the working fluid remains in a sub-cooled liquid state during and at the end of the auxiliary expansion.

[0056] The Applicant has verified that the refrigeration machine allows to obtain a much higher expansion efficiency than the possible two-phase expansion, with the additional advantage of not adding steam to be condensed in the subsequent mass accumulator. Also in this case, by sub-cooling, it is possible to partially or completely condense the vapour portion of the working fluid contained at the beginning of the charging, thus ensuring a constant or very small variation of the pressure in the mass accumulator during the charging phase, and reducing or completely eliminating the heat subtracted from the system during the charging phase.

[0057] In an aspect, the auxiliary refrigeration machine is operatively arranged between the mass accumulator and the pump. In the discharge configuration of the plant, the auxiliary refrigeration machine is configured to remove heat from the working fluid entering the pump and reduce the risk of possible cavitation of said pump.

[0058] On the one hand, prior to pumping the working fluid, during the discharge stage, heat may be optionally removed from the working fluid via an auxiliary chiller from the preceding aspect to reduce the risk of cavitation that may occur during subsequent pumping.

[0059] The applicant has demonstrated that increasing the subcooling in the inlet pump reduces the risk of cavitation and increases the available net positive suction head (NPSH).

[0060] This is an alternative to a configuration where the pump is placed several meters below the lowest level of the liquid to be pumped (to meet NPSH requirements). With the auxiliary chiller in suction mode, it achieves subcooling by lowering the fluid temperature while maintaining constant pressure.

[0061] On the one hand, heat exchange equipment is designed to exchange heat with the external environment.

[0062] On one hand, the heat exchange device includes: a thermal accumulator configured to exchange heat with a working fluid in a charge configuration and a discharge configuration; and a heat exchanger operatively connected to the thermal accumulator and the external environment.

[0063] The thermal accumulator is configured to store the heat (latent heat) of the working fluid during the charging phase and transfer that heat during the discharging phase.

[0064] On one hand, a heat exchanger is an air-guided cooler / refrigeration unit, or indirectly in contact with the atmosphere, for example, through a refrigeration fluid storage system and / or a cooling tower and / or an air cooler and / or a water cooler and / or a refrigeration unit with river or seawater.

[0065] On the one hand, the refrigeration unit is operatively connected to the heat exchange equipment.

[0066] In one aspect, removing heat from a mass accumulator and / or transferring heat to a mass accumulator includes: optionally exchanging heat directly or indirectly with the external environment via a heat exchange device according to one or more of the foregoing aspects.

[0067] On one hand, the thermal accumulator includes a first thermal accumulator at a high temperature and a second thermal accumulator at a low temperature.

[0068] On one hand, in the charging configuration, the first thermal accumulator at a high temperature cools the working fluid to an intermediate temperature (TD; TD1) above the critical temperature (Tcr), and the second thermal accumulator at a low temperature cools the working fluid from the intermediate temperature (TD1) to a final cooling temperature (TE) close to the critical temperature (Tcr).

[0069] On one hand, each of the operations in the charging phase of cooling the working fluid and the discharging phase of heating the working fluid can be performed in two phases via the first thermal accumulator at a high temperature and the second thermal accumulator at a low temperature, as described above.

[0070] On one hand, during the charging phase, in the first stage the working fluid is cooled to an intermediate temperature (TD) above the critical temperature (Tcr), and in the second stage the working fluid is cooled from the intermediate temperature (TD) to a final cooling temperature (TE) close to the critical temperature (Tcr).

[0071] On the one hand, the ratio between the intermediate temperature (TD) in Kelvin and the critical temperature (Tcr) in Kelvin is between 1.01 and 2.0, preferably between 1.1 and 1.3.

[0072] The purpose of dividing it into the two stages mentioned above is to make the thermal accumulator unaffected by the actual gas near the critical point, especially by the change in specific heat with temperature.

[0073] On one hand, the second thermal accumulator, which is located at a low temperature, includes a first heat exchanger and a second heat exchanger configured to exchange heat with the working fluid.

[0074] On one hand, the second thermal energy storage device at a low temperature includes: a first storage device at a low temperature, a second storage device at an intermediate temperature, and a third storage device at a high temperature. The first, second, and third storage devices may optionally contain water at ambient pressure and be fluidly connected to the first and second heat exchangers.

[0075] On one hand, the first heat exchanger and the second heat exchanger are arranged in series on the working fluid pipeline.

[0076] On the one hand, the water flow rates in the first heat exchanger and the second heat exchanger are different from each other.

[0077] The applicant has demonstrated that the structure shown above can improve the efficiency of the second thermal accumulator at low temperatures by minimizing the difference in heat exchange temperature (near the critical point where the specific heat changes with temperature).

[0078] On the one hand, the final cooling temperature (TE) in the charging configuration is greater than the pump discharge temperature (TC') in the discharging configuration.

[0079] The applicant has demonstrated that this allows for a zero-energy system for the “cooler” portion of the thermal accumulator (the second thermal accumulator at a low temperature), i.e., enabling the use of all the heat stored during the charging phase during the discharge phase.

[0080] On one hand, the heat transfer device is operatively connected to the working fluid line located downstream of the expander and the working fluid line located downstream of the pump.

[0081] On one hand, in the discharge configuration, the heat transfer device is configured to transfer a portion of the discharge heat from the expander to the supercritical working fluid downstream of the pump.

[0082] On one hand, the heat transfer device is connected to a second thermal accumulator that is at a low temperature.

[0083] On one hand, the heat transfer device is fluidly connected to the first heat exchanger and the second heat exchanger.

[0084] In terms of alternatives, the heat transfer device is fluidly connected to an additional heat exchanger arranged in parallel with the first and second heat exchangers.

[0085] On the one hand, the heat transfer device is also operatively connected to a heat exchange device to remove excess heat.

[0086] On the one hand, during the emission phase, it is configured to optionally transfer a portion of the excess heat transferred to the external environment via a heat exchange device.

[0087] On the one hand, the heat transfer device is operatively connected to the heat exchange equipment via a second thermal accumulator at a low temperature.

[0088] On one hand, the heat exchange loop connected to the heat exchange equipment is coupled to a second thermal accumulator at a low temperature to exchange heat with water leaving the first heat exchanger and / or leaving the second heat exchanger during the discharge phase / configuration.

[0089] On one hand, during the discharge phase, it is configured such that, either before or during heating the working fluid, a portion of the heat of the expanding working fluid is transferred to the working fluid in a supercritical state via a heat transfer device according to one or more of the foregoing aspects.

[0090] The applicant has demonstrated that this allows for the emission phase to be performed at a higher pressure than the charge pressure, thereby improving cycle efficiency.

[0091] On one hand, a first auxiliary heat exchanger is placed between the gas meter and the compressor inlet and is configured to regulate the compressor inlet temperature (TB; TB1).

[0092] On one hand, the first additional heat exchanger is configured to perform preheating (preheating) by utilizing, for example, the heat generated by the mechanical and electrical inefficiencies of the compressor.

[0093] On one hand, the first additional heat exchanger is configured to perform precooling by transferring heat to the environment, for example by means of a dry cooler, tower, seawater, river water, or refrigeration unit.

[0094] On one hand, a first additional heat exchanger is operatively connected to the heat exchange equipment.

[0095] On one hand, during the charging phase, the temperature (TA) of the working fluid from the gas meter before compression is optionally adjusted via a first additional heat exchanger according to one or more of the foregoing aspects.

[0096] On one hand, a second auxiliary heat exchanger is placed between the outlet of the expander and the gas meter and is configured to regulate the gas meter inlet temperature (TG').

[0097] On one hand, a second additional heat exchanger is operatively connected to the heat exchange equipment.

[0098] On one hand, during the emission phase, the temperature (TF') of the expanded working fluid before entering the gas meter is optionally adjusted via a second heat exchanger according to one or more of the foregoing aspects.

[0099] On one hand, the first and second additional heat exchangers are defined by the same exchanger.

[0100] On the one hand, the regenerator functions operationally between the gas meter and the compressor, and between the gas meter and the expander.

[0101] On the one hand, the regenerator is also operatively connected to the thermal accumulator.

[0102] On one hand, the regenerator is configured to exchange heat between the working fluid flowing through the thermal accumulator and the working fluid entering the compressor in the charging configuration or leaving the expander in the discharging configuration.

[0103] On one hand, during the charging phase, the system is configured to use a portion of the heat removed from the working fluid during cooling to the final cooling temperature (TE) to heat the working fluid prior to compression. This allows for an optional increase in the specific work of the cycle during the charging phase via a regenerator according to one or more of the foregoing aspects.

[0104] On one hand, during the discharge phase, the system is configured to optionally use a portion of the heat recovered from the expanded working fluid via a regenerator according to one or more of the foregoing aspects to further heat the working fluid after pumping and before expansion. This allows for increased cycle efficiency during the discharge phase.

[0105] On the one hand, the regenerator is operatively inserted between the first thermal accumulator, which is at a high temperature, and the second thermal accumulator, which is at a low temperature.

[0106] On one hand, the regenerator is configured to exchange heat between the working fluid flowing between a first thermal accumulator at a high temperature and a second thermal accumulator at a low temperature, and the working fluid entering the compressor in the charging configuration or leaving the expander in the discharging configuration.

[0107] On one hand, the second compressor is connected in series with the compressor and the second expander is connected in series with the expander.

[0108] On one hand, in the charging configuration, the first thermal accumulator, which is at a high temperature, operates between the compressor and the second compressor and also downstream of the second compressor.

[0109] On one hand, in the emission configuration, the first thermal accumulator, which is at a high temperature, is upstream of the second expander and also operates operatively between the second expander and the expander.

[0110] On one hand, during the charging phase, compressing and cooling the working fluid includes: optionally performing a first compression via a compressor according to one or more of the foregoing aspects, a first thermal accumulator at a high temperature, and a second compressor, followed by a first cooling, and then performing a second compression, followed by a second cooling.

[0111] On the one hand, at the end of the first compression, the working fluid is at a subcritical pressure (PC1), and at the end of the second compression, the working fluid is at a pressure above the critical pressure (Pcr) (PC2).

[0112] On the one hand, the temperatures (TC1, TC2) of the working fluid are similar or equal at the end of the first and second compressions.

[0113] On one hand, during the discharge phase, heating and expanding the working fluid includes: optionally performing a first heating via an expander according to one or more of the foregoing aspects, a first thermal accumulator and a second expander at a high temperature, followed by a first expansion, and then performing a second heating, followed by a second expansion.

[0114] Other features and advantages will become clearer from the detailed description of preferred, but not exclusive, embodiments of the facilities and processes according to the invention. Attached Figure Description

[0115] The description will now be illustrated with reference to the accompanying drawings, which are provided for illustrative purposes only and are therefore not limiting. In the drawings:

[0116] ▪ Figure 1 An embodiment of a facility for energy management according to the present invention is illustrated schematically;

[0117] ▪Figure 2 It is about Figure 1 TS diagram of the facilities;

[0118] ▪ Figure 3 A first variation of the facility according to the invention is shown schematically;

[0119] ▪ Figure 4 It is about Figure 3 TS diagram of the facilities;

[0120] ▪ Figure 5 This is a schematic diagram showing one of the elements mentioned in the preceding or following diagrams of the facility;

[0121] ▪ Figure 6 A second variation of the facility according to the invention is illustrated schematically;

[0122] ▪ Figure 7 It is about Figure 6 TS diagram of the facilities;

[0123] ▪ Figure 8 This is a schematic diagram showing the different components of the facility mentioned in the preceding or following diagrams;

[0124] ▪ Figure 9 It is about Figure 8 A portion of the TS diagram of the component;

[0125] ▪ Figure 10 A third variation of the facility according to the invention is illustrated schematically;

[0126] ▪ Figure 10A yes Figure 10 Enlarged view of the part;

[0127] ▪ Figure 11 It is about Figure 10 Part of the TS map of the facility;

[0128] ▪ Figure 12 A fourth variation of the facility according to the invention is schematically shown;

[0129] ▪ Figure 13 It is about Figure 12 TS diagram of the facilities;

[0130] ▪ Figure 14 A fifth variation of the facility according to the invention is illustrated schematically;

[0131] ▪ Figure 15 It is about Figure 14 TS diagram of the facilities;

[0132] ▪ Figure 16A sixth variation of the facility according to the invention is illustrated schematically;

[0133] ▪ Figure 17 It is about Figure 16 TS diagram of the facilities. Detailed Implementation

[0134] Referring to the accompanying drawings, reference numeral 1 generally indicates the facility for energy management according to the invention.

[0135] Figure 1 and Figure 2

[0136] Figure 1 The facility includes carbon dioxide (CO2) as the working fluid. In variations within the scope of this invention, the working fluid may be a mixture comprising carbon dioxide as a primary component, or SF6, N2O, or a mixture thereof.

[0137] Carbon dioxide is confined within a closed loop that performs a closed thermodynamic cycle conversion (TTC) between two mass accumulations of the carbon dioxide (CO2), first in one direction in the charge configuration / stage and then in the opposite direction in the emission configuration / stage.

[0138] For this purpose, facility 1 includes a gas meter 2 that internally defines a variable volume 3 that contains or is configured to contain carbon dioxide in the gas phase and at a constant first storage pressure (PAG') equal to or slightly above atmospheric pressure.

[0139] In the illustrated embodiment, the gas meter 2 is a dual-membrane type and includes an inner membrane 201 that contains carbon dioxide and an outer membrane 202 that is in contact with the external environment. The gas meter 2 is disposed on a surface and is in contact with atmospheric air externally. The inner membrane 201 of the gas meter 2 defines a volume 3 internally, which is configured to contain carbon dioxide at atmospheric pressure or substantially atmospheric pressure, i.e., in pressure equilibrium with the atmosphere. The outer membrane 202 maintains its own shape except for minor changes, in order to protect the inner membrane 201 from the effects of external environmental and atmospheric factors such as sun, rain, wind, snow, etc. The gap defined between the inner membrane 201 and the outer membrane 202 is filled with ambient air by means of a ventilator and maintained at a constant pressure of a few millibars. The gas meter 2 can also be implemented as any other low or zero overpressure gas storage system, wherein the pressure remains constant or substantially constant as the volume of the working fluid changes.

[0140] Facility 1 includes a compressor 4 fluidly connected to a gas flow meter 2 and an expander 5 fluidly connected to the gas flow meter 2. The compressor 4 is, for example, a centrifugal compressor driven by a corresponding motor 6. The expander 5 is, for example, a radial or axial turbine connected to a generator 7. A first line 8 connects the gas flow meter 2 to the inlet 4a of the compressor 4 and in parallel to the outlet 5b of the expander 5.

[0141] Facility 1 includes a thermal accumulator 9, which is fluidly connected to compressor 4 and expander 5 and configured to exchange heat with carbon dioxide. The thermal accumulator 9 is a TES (thermal energy storage device) comprising a thermoplastic mass (e.g., water, oil, or molten salt, or a solid material) capable of receiving, absorbing, and storing heat transferred from transported carbon dioxide in direct or indirect contact with the thermoplastic mass (via a heat exchanger), or capable of transferring previously accumulated heat to transported carbon dioxide in direct or indirect contact with the thermoplastic mass (via a heat exchanger). A second line 10 connects the outlet 4b of compressor 4 to thermal accumulator 9 and connects the inlet 5a of expander 5 in parallel to thermal accumulator 9.

[0142] Facility 1 includes a mass accumulator 11 that internally defines a constant volume 12 that contains or is configured to contain a working fluid in the liquid phase at a second storage pressure (PA'H). The mass accumulator 11 is schematically shown in the accompanying drawings and may include, for example, one or more reservoirs, such as metallic reservoirs, suitable for withstanding the second storage pressure (PA'H) without substantially deforming, i.e., maintaining a constant volume (or corresponding volume) 12. A third line 13 connects a thermal accumulator 9 to the inlet 11a of the mass accumulator 11 and, in parallel, to the outlet 11b of the mass accumulator 11. A first branch 13a of the third line 13 connects the thermal accumulator 9 to the inlet 11a of the mass accumulator 11, and a second branch 13b of the third line 13 connects the outlet 11b of the mass accumulator 11 to the thermal accumulator 9.

[0143] A pressure-reducing device 14 is arranged between the thermal accumulator 9 and the mass accumulator 11. This pressure-reducing device 14 is configured to reduce the pressure of carbon dioxide flowing from the thermal accumulator 9 toward the mass accumulator 11 in the first branch 13a of the third line 13. Alternatively, a pump 15 is arranged on the second branch 13b of the third line 13 to pump carbon dioxide from the mass accumulator 11 toward the thermal accumulator 9 according to the method described below.

[0144] Facility 1 also includes a heat exchange device 16, which is operatively coupled to the mass accumulator 11 and configured to exchange heat with the working fluid present in the mass accumulator 11.

[0145] The first pipeline 8, the second pipeline 10, and the third pipeline 13 mentioned herein are configured together with electrical or electronic control devices (e.g., actuating valves, control units, sensors, etc.) to operate facility 1 in the mentioned charge configuration / stage and the mentioned discharge configuration / stage according to the method of the invention and according to the closed thermodynamic cycle conversion (TTC).

[0146] This method will refer to Figure 1 as well as Figure 2 The TS diagram is used to describe this.

[0147] In its initial state, almost all of the carbon dioxide present in facility 1 is contained within the internal volume 3 of gas meter 2, and is in pressure equilibrium with the external atmosphere. Figure 2 -Point A), which is in the gas phase and at a constant and substantially equal first storage pressure (PAG').

[0148] In the filling configuration / stage ( Figure 1 and Figure 2 In the process of (points A-C-E-G-H), carbon dioxide is transported from gas meter 2 through compressor 4, thermal accumulator 9, and pressure reducing device 14 to mass accumulator 11, and accumulates in the mass accumulator 11 in the liquid phase at the second storage pressure (PA'H).

[0149] Specifically, compressor 4 compresses the carbon dioxide exiting the internal volume 3 of gas meter 2 to a final compression pressure (PC) higher than the critical pressure (Pcr) of the working fluid. Figure 1 and Figure 2 (From point A to point C). For example, the ratio between the final compressibility pressure (PC) and the critical pressure (Pcr) of carbon dioxide is 2. Carbon dioxide is heated to the final compressibility temperature (TC) corresponding to the final compressibility pressure (PC).

[0150] Then, as supercritical carbon dioxide passes through thermal accumulator 9, the thermal accumulator 9 absorbs and stores the heat from the carbon dioxide. The carbon dioxide is cooled to a final cooling temperature (TE) close to the critical temperature (Tcr) of carbon dioxide. Figure 1 and Figure 2 (From point C to point E). In the example shown, the final cooling temperature (TE) is below the critical temperature (Tcr) of the working fluid, but in other embodiments, the final cooling temperature (TE) may be slightly above the critical temperature. For example, the ratio between the final cooling temperature (TE) and the critical temperature (Tcr) of carbon dioxide in Kelvin is 0.90 or 1.01. For example, the ratio between the final cooling pressure (PE) and the critical pressure (Pcr) of carbon dioxide is 2.

[0151] At this point, supercritical carbon dioxide enters pressure reducing device 14, which reduces the pressure of the supercritical carbon dioxide to a reduced pressure (PG) below the corresponding critical pressure (Pcr). For example, the ratio between the reduced pressure (PG) and the critical pressure (Pcr) of carbon dioxide is 0.68.

[0152] Carbon dioxide cooled to a reduced temperature (TG) Figure 1 and Figure 2 (From point E to point G). Figure 2 The diagram illustrates the pressure reduction (e.g., the EG section, where G is inside the Andrews bell diagram) achieved by operating the pressure reducing device 14 defined by the pressure relief valve.

[0153] The carbon dioxide exiting the superposition valve is stored in the mass accumulator 11 at a second storage pressure (PA'H), which may correspond to the reduced pressure (PG) or may differ slightly from the reduced pressure (PG), for example, by a few bar (e.g., from 1 bar to 5 bar) and be below the critical pressure (Pcr). The carbon dioxide is in equilibrium with its own vapor phase. Figure 1 and Figure 2 (Point H). For example, the second storage pressure (PA'H) is equal to 50 bar, and the ratio between the second storage pressure (PA'H) of carbon dioxide and the critical pressure (Pcr) (73 bar) is equal to 0.68. A liquid-vapor separator may be present between the superimposed valve and the mass accumulator 11, or a region within the mass accumulator 11 may be used to separate the vapor phase from the liquid phase.

[0154] When carbon dioxide in the general liquid phase enters and fills the mass accumulator 11, the heat exchange device 16 removes heat from the mass accumulator 11 to condense a portion of the vapor phase of the carbon dioxide contained in the mass accumulator 11 and maintain the second storage pressure (PA'H) constant or substantially constant.

[0155] In other words, the increase in volume occupied by carbon dioxide stored in the mass accumulator 11 in the liquid phase (i.e., the decrease in volume occupied by working fluid vapor) is compensated by condensing all or part of the vapor in the carbon dioxide vapor already contained in the mass accumulator 11 and the vapor of carbon dioxide generated during depressurization.

[0156] In the filling configuration / stage, facility 1 absorbs electrical energy from the external power grid that feeds power to motor 6 of compressor 4 and stores it in the form of heat and pressure.

[0157] At the end of the emission phase (point H), the carbon dioxide present in facility 1 is almost entirely contained in the internal volume 12 of mass accumulator 11 (a two-phase mass accumulator under subcritical conditions) in a liquid phase in equilibrium with its own limited vapor phase. Within the internal volume 12 of mass accumulator 11, there is no separating membrane between the liquid and vapor phases of the carbon dioxide.

[0158] In emission configuration / stage ( Figure 1 and Figure 2 In the process of (points A'-B'-C'-E'-G'), carbon dioxide is transported from mass accumulator 11 to gas meter 2 via pump 15, thermal accumulator 9 and expander 5, and is stored again in gas meter 2 in the gas phase at a constant first storage pressure (PAG') in pressure equilibrium with the atmosphere.

[0159] Specifically, pump 15 pumps liquid carbon dioxide at a discharge pressure (PC') higher than the critical pressure (Pcr) of carbon dioxide. Figure 1 and Figure 2 (Point B' - Point C'). Carbon dioxide is heated to emission temperature (TC').

[0160] Then, as the carbon dioxide passes through the thermal accumulator 9, the thermal accumulator 9 transfers the previously accumulated heat to the carbon dioxide. The carbon dioxide is heated to the final heating temperature (TE'). Figure 1 and Figure 2 (From point C' to point E').

[0161] Then, the carbon dioxide expands inside the expander 5, thereby moving the mechanical mechanism of the expander 5, for example, rotating one or more impellers of the turbine, and generating electrical energy via the generator 7. Figure 3 and Figure 4 (Point E' - Point G'). In the emission configuration / stage, facility 1 uses previously stored heat and pressure to generate energy. Carbon dioxide exiting expander 5 is stored again in gas meter 2 at a first storage pressure (PAG').

[0162] In the emission configuration, the heat exchange device 16 transfers heat to the mass accumulator 11 to cause a portion of the liquid phase of carbon dioxide contained in the mass accumulator 11 to evaporate, and to maintain the second storage pressure (PA'H) constant or substantially constant.

[0163] In other words, during the emission phase / configuration, in order to maintain a constant or substantially constant pressure in the mass accumulator 11, the reduction in the volume of carbon dioxide in the liquid phase (i.e., the increase in the volume occupied by carbon dioxide vapor) is compensated by evaporating a portion of the liquid carbon dioxide, so that the mass accumulator 11 does not depressurize and does not cool.

[0164] Figure 3 and Figure 4 - first variant

[0165] Figure 1 and Figure 2 A first variant of facility 1 (and corresponding method) is schematically shown, which differs from the above-described one due to the additional presence of a refrigeration unit 17 and an auxiliary refrigeration unit 18. Figure 3 and Figure 4 Facility 1. The chiller 17 is arranged on the first branch 13a of the third pipeline 13 and inserted between the thermal accumulator 9 and the pressure reducing device 14.

[0166] In the filling configuration / stage ( Figure 2 and Figure 4 In the sequence (points A-C-E-F-G-H), the refrigeration unit 17 removes heat from the carbon dioxide entering the stacking valve, such that the final depressurization temperature (TG) of the carbon dioxide leaving the stacking valve is lower than the saturation temperature of the carbon dioxide at the reduced pressure (PG), which corresponds to or is slightly different from the second storage pressure (PA'H). Figure 3 The TS diagram is different, in Figure 5 In the process, carbon dioxide moves from point E to point F (refrigeration) and then to point G (superposition) and then rises toward point H. The removal of heat from the carbon dioxide entering the pressure reducing device 14 by the refrigeration unit 17 allows for the reduction and / or elimination of the vapor dryness of carbon dioxide at the outlet of the pressure reducing device 14.

[0167] The auxiliary chiller 18 is operatively arranged on the second branch 13b of the third pipeline 13 and inserted between the mass accumulator 11 and the pump 15.

[0168] In the emission configuration / stage, the auxiliary chiller 18 allows heat to be removed from the carbon dioxide entering the pump 15 and reduces the risk of cavitation that may occur in the pump 15 during pumping. This subcooling (supercooling) at the inlet of the pump 15, in addition to reducing the risk of cavitation, increases the available net positive suction head (NPSH).

[0169] Figure 5 The pressure reducing device 14 of the facility may also be an auxiliary expander, such as an auxiliary turbine, an action turbine, or a Balton turbine, rather than a pressure-reducing valve. The auxiliary expander is connected to an auxiliary generator (not shown), and the auxiliary expander is capable of extracting energy during the charging phase / configuration and converting it into mechanical and / or electrical energy.

[0170] In this other variation, the refrigerator 17 removes heat from the carbon dioxide before it enters the auxiliary expander, keeping the carbon dioxide in a subcooled liquid state at the outlet of the auxiliary expander. This allows for an expansion efficiency far exceeding that of possible two-phase expansion.

[0171] The chiller 17 and the auxiliary chiller 18 can also be connected to the heat exchange device 16 to exchange heat with the heat exchange device 16 and with the external environment.

[0172] Figure 5 - heat exchange device

[0173] Figure 6 A schematic example of a heat exchange device 16, which is combined with a mass accumulator 7 and can be used in the facility shown here, is illustrated.

[0174] In this example, the heat exchange device 16 is configured to exchange heat not only with the carbon dioxide contained in the mass accumulator 11 but also with the external environment. Therefore, the heat exchange device 16 allows heat to be removed from the mass accumulator 11 and / or transferred to the mass accumulator 11 that is exchanging heat with the external environment.

[0175] The heat exchange device 16 shown includes a thermal accumulator 19 configured to exchange heat with carbon dioxide and a heat exchanger 20 operatively connected to the thermal accumulator 19 and the external environment. The thermal accumulator 19 stores the heat Q (latent heat) of carbon dioxide during the charging phase / configuration and transfers the heat Q to the carbon dioxide during the emission phase / configuration.

[0176] exist Figure 7 In the example, the thermal accumulator 19 includes a corresponding loop 21 in which the heat carrier is circulated. The loop 21 extends inside the mass accumulator 11 to exchange heat with the carbon dioxide and the thermomass of the thermal accumulator 19.

[0177] The heat exchanger 20 includes a corresponding loop 22 in which a heat carrier is circulated. The loop 22 extends into the interior of the thermal accumulator 19 to exchange heat with the thermal mass of the thermal accumulator 19 and the environment. In a variant of the implementation, the loop 22 may be reversed, i.e., the same device used to store heat in the thermal accumulator 19 is used to exchange heat with the heat exchanger 20.

[0178] The heat exchanger 20 may be an air-guided cooler / refrigeration unit, or indirectly in contact with the atmosphere, for example, through a refrigeration fluid storage system and / or a cooling tower and / or an air cooler and / or a water cooler and / or a refrigeration unit with river or seawater.

[0179] The bypass circuit 23 allows the circuit 22 of the thermal accumulator 19 to be directly fluidly connected to the circuit 22 of the heat exchanger 20.

[0180] Figure 8 、 Figure 9 、 Figure 6 and Figure 7 — second variant

[0181] Figure 1 and Figure 2 A second variant of facility 1 (and corresponding method) is schematically shown, which is consistent with the above.Figure 3 and Figure 4 The difference between facility 1 and facility 2 is that it includes facilities for... Figure 7 and Figure 8 The device shown includes a refrigeration unit 17, and a thermal accumulator 9 comprising a first thermal accumulator 9a at a high temperature and a second thermal accumulator 9b at a low temperature. The dual thermal accumulators 9a and 9b allow for the execution of each operation in two phases: cooling carbon dioxide during the charging phase and heating carbon dioxide during the emission phase.

[0182] Reference Figure 9 The TS diagram shows that, in the charging configuration / stage, the first thermal accumulator 9a, located at a high temperature, cools the carbon dioxide to an intermediate temperature (TD) above the critical temperature (Tcr), and the second thermal accumulator 9b, located at a low temperature, cools the carbon dioxide from the intermediate temperature (TD) to a final cooling temperature (TE) close to the critical temperature (Tcr). The ratio between the intermediate temperature (TD) and the critical temperature (Tcr) is, for example, equal to 1.3.

[0183] In the emission configuration / stage, the second thermal accumulator 9b, which is at a low temperature, heats carbon dioxide to an intermediate temperature (TD') above the critical temperature (Tcr), while the first thermal accumulator 9a, which is at a high temperature, heats carbon dioxide from the intermediate temperature (TD') to the final heating temperature (TE').

[0184] Figure 9 This is a schematic example of a second thermal energy storage device 9b operating at a low temperature. In this example, the second thermal energy storage device 9b operating at a low temperature includes a first heat exchanger 24a and a second heat exchanger 24b, which are arranged in series on a second pipeline 10 and configured to exchange heat with carbon dioxide flowing through the second pipeline 10.

[0185] The second thermal accumulator 9b, which is at a low temperature, also includes a first storage unit 25a, which is at a low temperature, a second storage unit 25b, which is at an intermediate temperature, and a third storage unit 25c, which is at a high temperature.

[0186] Conduit 26 connects the first reservoir 25a in series with the first heat exchanger 24a, the second heat exchanger 24b, and the third reservoir 25c. Auxiliary conduit 27 connects the second reservoir 25b to the point on conduit 26 located between the first heat exchanger 24a and the second heat exchanger 24b. Conduit 26 exiting the first reservoir 25a is equipped with a corresponding first pump 28a and a first shut-off and regulating valve 29a arranged in parallel. Conduit 26 exiting the second reservoir 25c is equipped with a corresponding third pump 28c and a third shut-off and regulating valve 29c arranged in parallel. Auxiliary conduit 27 exiting the second reservoir 25b is equipped with a corresponding second pump 28b and a second shut-off and regulating valve 29b arranged in parallel.

[0187] The first reservoir 25a, the second reservoir 25b, and the third reservoir 25c contain unpressurized water, i.e., water at ambient pressure. A first pump 28a is configured to pump water from the first reservoir 25a toward the first heat exchanger 24a. A second pump 28b is configured to pump water from the second reservoir 25a toward the connection point of the auxiliary conduit 27 to the conduit 26. A third pump 28c is configured to pump water from the third reservoir 25c toward the second heat exchanger 24b. In this way, the water flow rates through the first heat exchanger 24a and the second heat exchanger 24b are different from each other. This minimizes the temperature difference in heat exchange between water and carbon dioxide, and thus improves the efficiency of the second thermal accumulator 9b, which operates at a low temperature.

[0188] Figure 10 The TS diagram partially shows the cooling carbon dioxide and the corresponding heating water routes (abc) during the filling phase (from point D to point E). Figure 10A The TS diagram also shows the heating of carbon dioxide and the corresponding cooling water path (cba) during the emission phase (from point C' to point D'). The final cooling temperature (TE) in the charge configuration is greater than the pump discharge temperature (TC') in the emission configuration. This allows for a zero-energy system for the "cooler" portion of the thermal accumulator, i.e., for the second thermal accumulator 9b at a cryogenic temperature, meaning that all the heat stored during the charge phase can be used during the emission phase.

[0189] Figure 11 、 Figure 10 and Figure 10A - Third variant

[0190] Figure 11 , Figure 6 and Figure 7 A third variation of facility 1 (and corresponding method) is schematically shown, which is different from the second variation described above. Figure 8 , Figure 9 , Figure 10A and Figure 8 The difference between facility 1 and facility 2 is that it also includes a heat transfer device 30, which is operatively connected to a first line 8 of the working fluid downstream of the outlet 5b of the expander 5 and a third line 13 of the working fluid downstream of the pump 15. In the discharge configuration / stage, the heat transfer device 30 is configured to transfer a portion of the discharge heat from the expander 5 to the supercritical working fluid downstream of the pump 15.

[0191] In addition, the second thermal accumulator 9b, which is located at a low temperature ( Figure 8 )and Figure 11 The thermal accumulator shown in the second variant is similar to, but not the same as, that described above. Figure 10Unlike the thermal accumulators in the first reservoir 25c, the third pump 28c of the third reservoir 25c is placed on the loop section 31 extending to the heat exchanger 32, which is arranged on the first pipeline 8 and downstream of the outlet 5b of the expander 5. In the discharge configuration / stage, the third pump 28c is configured to pump water from the third reservoir 25c toward the heat exchanger 32 and back toward the second heat exchanger 24b.

[0192] Therefore, the heat transfer device 30 includes the loop section 31 with a corresponding heat exchanger 32. Thus, a portion of the heat discharged from the expander 5 is transferred via water in the second thermal accumulator 9b at a low temperature to the supercritical working fluid downstream of the pump 15.

[0193] In the charging configuration / stage, the third pump 28c is inoperable, the third shut-off and regulating valve 29c is open and in a regulating state, and the first pump 28a and the second pump 28b are operational. In the effluent configuration / stage, the closed third shut-off and regulating valve 29c and the third pump 28c are operational.

[0194] Figure 10A This is part of a TS diagram, illustrating the effect of transferring a portion of the exhaust heat from the expander 5 to the supercritical working fluid downstream of the pump 15 via heat transfer device 30. In the charging phase / configuration, carbon dioxide is cooled (DE), while water is heated (abc). In the discharge phase / configuration, water is cooled along the higher line (c'-b'-a') by the action of heat transfer device 30, and carbon dioxide is heated from C' to D'.

[0195] In a variant not shown, the heat transfer device 30 is fluidly connected to an additional heat exchanger, which is placed in parallel with the first heat exchanger 24a and the second heat exchanger 24b.

[0196] like Figure 5 and Figure 12 As shown, the heat transfer device 30 is also operatively connected to the heat exchange device 16 for the purpose of removing any excess heat and transferring it to the external environment. The heat transfer device 30 is operatively and indirectly connected to the heat exchange device 16 via a second thermal accumulator 9b at a cryogenic temperature. For this purpose, the heat exchange loop 33 includes a corresponding heat exchanger 34 operatively connected at a point between the first heat exchanger 24a and the second heat exchanger 24b to a conduit 26 of the second thermal accumulator 9b at a cryogenic temperature to exchange heat with water leaving the first heat exchanger 24a during the discharge phase / configuration. A corresponding loop 35 connects this corresponding heat exchanger 34 to the heat exchange device 16, for example, with… Figure 13 The thermal accumulator circuit 21 of thermal accumulator 19 is connected.

[0197] Figure 12 and Figure 13 - fourth variant

[0198] Figure 1 and Figure 2 A fourth variation of facility 1 (and corresponding method) is schematically shown, which is consistent with the above. Figure 3 and Figure 4 The difference between facility 1 and this fourth variant is that it includes features targeting Figure 13 and Figure 5 The device shown is a refrigeration unit 17, which includes a first auxiliary heat exchanger 36 placed between the gas meter 2 and the inlet 4a of the compressor 4, and a second auxiliary heat exchanger 37 placed between the outlet 5b of the expander 5 and the gas meter 2.

[0199] The first auxiliary heat exchanger 36 is configured to regulate the compressor inlet temperature (TB), i.e., modify the temperature (TA) of carbon dioxide from the gas meter 2 before compression. The first auxiliary heat exchanger 36 can be configured, for example, to perform preheating using heat generated by the mechanical and electrical inefficiencies of the compressor 4. Figure 13 Preheating (A-B) in the process, or precooling (precooling) is performed, for example, by transferring heat to the environment using a dry cooler, tower, seawater, river water, or chiller.

[0200] In the illustrated and example embodiments, the first additional heat exchanger 36 includes a connection to the heat exchange device 16, for example, with... Figure 5 The corresponding circuit 38 is connected to the thermal accumulator circuit 21 of the thermal accumulator 19.

[0201] The second additional heat exchanger 37 is configured to regulate the inlet temperature (TG') of the gas meter 2, that is, to modify the temperature (TF') of the expanding carbon dioxide before it enters the gas meter 2. Figure 14 The cooling of F'-G' after the expansion of E'-F' in the emission stage / configuration is shown.

[0202] In the illustrated and example embodiments, the second additional heat exchanger 37 includes a connection to the heat exchange device 16, for example, with... Figure 15 The thermal accumulator circuit 21 of the thermal accumulator 19 is connected to the corresponding circuit 39. The corresponding circuit 39 of the second auxiliary heat exchanger 37 may be connected to or partially overlap with the corresponding circuit 38 of the first auxiliary heat exchanger 36. In a variation of the embodiment, the first auxiliary heat exchanger 36 and the second auxiliary heat exchanger 37 may also be defined by a single exchanger.

[0203] Figure 14 and Figure 15 - Fifth variant

[0204] Figure 6 and Figure 7 A fifth variation of facility 1 (and corresponding method) is schematically shown, which is related to the above.Figure 15 and Figure 15 The second variant of facility 1 differs in that it includes a second additional heat exchanger 37 of the fourth variant and also includes a regenerator 40.

[0205] The regenerator 40 operates operatively between the gas meter 2 and the compressor 4, and between the gas meter 2 and the expander 5, and is operatively connected to the thermal accumulator 9. In particular, the regenerator 40 is operatively inserted between the first thermal accumulator 9a, which is at a high temperature, and the second thermal accumulator 9b, which is at a low temperature.

[0206] The carbon dioxide pipeline connecting the first thermal accumulator 9a at a high temperature and the second thermal accumulator 9b at a low temperature is thermally connected to the first pipeline 8 at the regenerator 40, and the second additional heat exchanger 37 is operatively inserted between the gas meter 2 and the regenerator 40.

[0207] In the charging configuration / stage, the regenerator 40 allows heat exchange between carbon dioxide flowing from the first thermal accumulator 9a at a high temperature toward the second thermal accumulator 9b at a low temperature and the carbon dioxide entering the compressor 2. In the charging configuration / stage, a portion of the heat removed from the carbon dioxide during cooling to the final cooling temperature (TE) is used to heat the carbon dioxide before compression. Figure 16 (D1-D2, AB).

[0208] In the emission configuration / stage, the regenerator 40 allows heat exchange between carbon dioxide flowing from the low-temperature second thermal accumulator 9b toward the high-temperature first thermal accumulator 9a and carbon dioxide exiting the expander 5. In the emission configuration / stage, a portion of the heat recovered from the expanded carbon dioxide is used to further heat the carbon dioxide after pumping and before expansion. Figure 17 (F'1-F'3, D'1-D'2).

[0209] Figure 16 and Figure 17 - Sixth variant

[0210] Figure 14 and Figure 15 A sixth variant of facility 1 (and corresponding method) is schematically shown, which is related to the above. Figure 17 and Figure 17 The fifth variant of facility 1 differs in that it includes two compressors 4, 41 and two expanders 5, 43. The second compressor 41, which is mechanically connected to the motor 6 or, as shown, is provided with a corresponding second motor 42, and is in fact connected in series with the compressor 4. The second expander 42, which is mechanically connected to the generator 7 or, as shown, is provided with a corresponding second generator 44, and is connected in series with the expander 5.

[0211] Specifically, the outlet 4b of compressor 4 is connected to the inlet 41a of second compressor 41. The outlet 41b of second compressor 41 is connected to regenerator 40. The inlet 43a of second expander 43 is connected to regenerator 40, and the outlet 43b of second expander 43 is connected to inlet 5a of expander 5.

[0212] In the charging configuration / stage, the first thermal accumulator 9a, located at a high temperature, operably functions between the compressor 4 and the second compressor 41, and between the second compressor 41 and the regenerator 40. Therefore, in the charging configuration / stage, the first compression ( Figure 17 (B1-C1), followed by the first cooling ( Figure 17 (C1-B2), and then the second compression ( Figure 17 (B2-C2), followed by a second cooling ( Figure 17 (C2-D1). At the end of the first compression (C1), carbon dioxide is at a subcritical pressure (PC1), and at the end of the second compression, carbon dioxide is at a pressure above the critical pressure (Pcr) (PC2). The temperatures of carbon dioxide (TC1, TC2) at the end of the first and second compressions are similar or equal, and the temperatures of carbon dioxide (TB2, TD1) at the end of the first and second coolings are also similar or equal.

[0213] In the emission configuration / stage, the first thermal accumulator 9a, operating at a high temperature, functions operatively between the regenerator 40 and the second expander 43, and between the second expander 43 and the expander 5. Therefore, in the emission configuration / stage, the first heating ( Figure 17 (D'2-E'1), followed by the first expansion ( ​ (E'1-F'1), and then perform a second heating ( ​ F1'-E2'), followed by the second expansion ( ​ (E'2-F'2).

[0214] Component list 1. Facilities 2. Gas meter 201 Endometrium 202 Outer membrane 3. Internal gas meter volume 4. Compressor 4a Compressor inlet 4b Compressor outlet 5. Expander 5a Expander Inlet 5b Expander outlet 6 motors 7. Generator 8 First Pipeline 9. Thermal accumulator 9a First thermal accumulator 9b Second thermal accumulator 10 Second Pipeline 11 Mass accumulator 11a Mass accumulator inlet 11b Mass accumulator outlet 12 Internal mass accumulator volume 13 Third Pipeline 13a Third Pipeline First Branch 13b The second branch of the third pipeline 14 Pressure reducing device 15 pumps 16. Heat exchange equipment 17. Refrigeration unit 18 Auxiliary Refrigeration Unit 19 Thermal accumulators 20 Heat exchangers 21 Thermal accumulator circuit 22 Heat exchanger loop 23 Bypass circuit 24a First heat exchanger 24b Second heat exchanger 25a First Storage 25b Second Storage 25c Third Memory 26 catheters 27. Assistive catheter 28a First Pump 28b Second Pump 28c Third Pump 29a First shut-off and regulating valve 29b Second shut-off and regulating valve 29c Third shut-off and regulating valve 30 Heat transfer device 31 Circuit Section 32 Heat Exchanger 33 Heat exchange circuit 34 Heat Exchanger 35 loops 36 First Additional Heat Exchanger 37 Second Additional Heat Exchanger 38 First Additional Heat Exchanger Circuit 39 Second Additional Heat Exchanger Circuit 40 Regenerator 41 Second compressor 41a Second compressor inlet 41b Second compressor outlet 42 Second Motor 43 Second expander 43a Second expander inlet 43b Second expander outlet 44 Second Generator

Claims

1. A facility for energy management, comprising: Working fluids other than atmospheric air; Gas meter (2), the gas meter (2) internally defines a variable volume (3), the variable volume (3) containing or configured to contain the working fluid in a gas phase and at a constant first storage pressure (PAG') equal to or slightly above atmospheric pressure; A compressor (4; 4, 41) is fluidly connected to the gas meter (2); Expander (5; 5, 43), the expander (5; 5, 43) being fluidly connected to the gas meter (2); A thermal accumulator (9; 9a, 9b) is fluidly connected to the compressor (4; 4, 41) and the expander (5; 5, 43) and configured to exchange heat with the working fluid; A mass accumulator (11) internally defines a constant volume (12) containing or configured to contain the working fluid in a liquid phase at a second storage pressure (PA'H), and the mass accumulator (11) is fluidly connected to the thermal accumulator (9; 9a, 9b). Pressure reducing device (14) that operates operatively between the thermal accumulator (9; 9a, 9b) and the mass accumulator (11); Pump (15), which operates operatively between the thermal accumulator (9; 9a, 9b) and the mass accumulator (11); A heat exchange device (16) is operatively connected to the mass accumulator (11) and configured to exchange heat with the working fluid in the mass accumulator (11). Piping and control devices configured to operate the facility (1) in a filling configuration and a discharging configuration. In the charging configuration, the working fluid is delivered from the gas meter (2) to the mass accumulator (11) via the compressor (4; 4, 41), the thermal accumulator (9; 9a, 9b), and the pressure reducing device (14) and accumulates in the mass accumulator (11); the compressor (4; 4, 41) compresses the working fluid to a final compression pressure (PC; PC2) higher than the critical pressure (Pcr) of the working fluid; the thermal accumulator (9; 9a, 9b) absorbs heat from the working fluid and cools the working fluid to a final cooling temperature (TE) close to the critical temperature (Tcr) of the working fluid; the pressure reducing device (14) reduces the pressure of the working fluid to a reduced pressure (PG) lower than the critical pressure (Pcr) of the working fluid; the working fluid is stored in the mass accumulator (11) at a second storage pressure (PA'H) lower than the critical pressure (Pcr) of the working fluid and in equilibrium with the vapor phase of the working fluid itself. In the charging configuration, the heat exchange device (16) removes heat from the mass accumulator (11) to cause partial condensation of the vapor phase of the working fluid contained in the mass accumulator (11) and to maintain the second storage pressure (PA'H) in the mass accumulator (11) constant or substantially constant. In the discharge configuration, the working fluid is delivered from the mass accumulator (11) to the gas meter (2) via the pump (15), the thermal accumulator (9; 9a, 9b) and the expander (5; 5, 43) and accumulates in the gas meter (2); the pump (15) pumps the working fluid at a discharge pressure (PC') higher than the critical pressure (Pcr) of the working fluid; the thermal accumulator (9; 9a, 9b) transfers previously stored heat to the working fluid and heats the working fluid; the expander (5; 5, 43) expands the working fluid; and the working fluid is stored in the gas meter (2) at the first storage pressure (PAG'). In the emission configuration, the heat exchange device (16) releases heat to the mass accumulator (11) to cause partial evaporation of the liquid phase of the working fluid contained in the mass accumulator (11) and to maintain the second storage pressure (PA'H) in the mass accumulator (11) constant or substantially constant.

2. The facility according to claim 1, comprising a chiller (17) operatively disposed between the thermal accumulator (9; 9a, 9b) and the pressure reducing device (14); in the charging configuration of the facility (1), the chiller (17) is configured to remove heat from the working fluid entering the pressure reducing device (14) in order to reduce and / or eliminate the vapor dryness of the working fluid at the outlet of the pressure reducing device (14).

3. The facility according to claim 1 or 2, comprising an auxiliary chiller (18) operatively arranged between the mass accumulator (11) and the pump (15); in the discharge configuration of the facility (1), the auxiliary chiller (18) is configured to remove heat from the working fluid entering the pump (15) and reduce the risk of possible cavitation of the pump (15).

4. The facility according to any one of claims 1 to 3, wherein, The pressure reducing device (14) includes a pressure stacking valve.

5. The facility according to claim 4 when dependent on claim 2, wherein, The refrigerator (17) is configured to remove heat from the working fluid entering the stacking valve such that the final depressurization temperature (TG) of the working fluid leaving the stacking valve is lower than the saturation temperature of the working fluid at the reduced pressure (PG).

6. The facility according to any one of claims 1 to 3, wherein, The pressure reducing device (14) includes an auxiliary expander.

7. The facility according to claim 6 when dependent on claim 2, wherein, The refrigeration unit (17) is configured to remove heat from the working fluid entering the auxiliary expander, such that the working fluid remains in a liquid subcooled state until the outlet of the auxiliary expander.

8. The facility according to any one of claims 1 to 7, comprising a liquid-vapor separator operatively located between the pressure reducing device (14) and the mass accumulator (11).

9. The facility according to any one of claims 1 to 8, wherein, The heat exchange device (16) is configured to exchange heat with the external environment; optionally, the heat exchange device (16) includes a thermal accumulator (19) configured to exchange heat with the working fluid in the charge configuration and the discharge configuration, and a heat exchanger (20) operatively connected to the thermal accumulator (19) and the external environment.

10. The facility according to claim 9 when dependent on any one of claims 2, 5, or 7, wherein, The refrigeration unit (17) is operatively connected to the heat exchange device (16).

11. The facility according to any one of claims 1 to 10, wherein, The thermal accumulator (9; 9a, 9b) includes a first thermal accumulator (9a) at a high temperature and a second thermal accumulator (9b) at a low temperature; wherein, in the charging configuration, the first thermal accumulator (9a) at a high temperature cools the working fluid to an intermediate temperature (TD; TD1) above the critical temperature (Tcr), and the second thermal accumulator (9b) at a low temperature cools the working fluid from the intermediate temperature (TD1) to the final cooling temperature (TE) close to the critical temperature (Tcr).

12. The facility according to claim 11, wherein, The ratio of the intermediate temperature (TD) in Kelvin to the critical temperature (Tcr) in Kelvin is between 1.01 and 2.0, wherein the ratio of the final cooling temperature (TE) in Kelvin to the critical temperature (Tcr) in Kelvin is between 0.4 and 1.

1.

13. The facility according to claim 11 or 12, wherein, The second thermal accumulator (9b) at a low temperature includes: a first heat exchanger (24a) and a second heat exchanger (24b), the first heat exchanger (24a) and the second heat exchanger (24b) being configured to exchange heat with the working fluid; a first storage tank (25a) at a low temperature, a second storage tank (25b) at an intermediate temperature and a third storage tank (25c) at a high temperature, the first storage tank (25a), the second storage tank (25b) and the third storage tank (25c) containing water at ambient pressure and fluidly connected to the first heat exchanger (24a) and the second heat exchanger (24b); wherein the first heat exchanger (24a) and the second heat exchanger (24b) are arranged in series on the working fluid line; wherein the water flow rates in the first heat exchanger (24a) and the second heat exchanger (24b) are different from each other.

14. The facility according to any one of claims 1 to 13, wherein, The final cooling temperature (TE) in the filling configuration is greater than the pump discharge temperature (TC') in the discharge configuration.

15. The facility according to any one of claims 1 to 14, comprising a heat transfer device (30) operatively connected to a working fluid line downstream of the expander (5; 5, 43) and a working fluid line downstream of the pump (15); wherein, In the discharge configuration, the heat transfer device (30) is configured to transfer a portion of the discharge heat from the expander (5; 5, 43) to the working fluid in a supercritical state.

16. The facility according to claim 15 when dependent on any one of claims 11 to 13, wherein, The heat transfer device (30) is connected to the second thermal accumulator (9b) which is at a low temperature.

17. The facility according to claim 15 when dependent on claim 13, wherein, The heat transfer device (30) is fluidly connected to the first heat exchanger (24a) and the second heat exchanger (24b), or the heat transfer device (30) is fluidly connected to an additional heat exchanger arranged in parallel with the first heat exchanger (24a) and the second heat exchanger (24b).

18. The facility according to any one of claims 15 to 17, wherein, The heat transfer device (30) is also operatively connected to the heat exchange device (16) to remove excess heat.

19. The facility according to claim 18 when dependent on claim 16 or 17, wherein, The heat transfer device (30) is operatively connected to the heat exchange device (16) via the second thermal accumulator (9b) which is at a low temperature.

20. The facility according to any one of claims 1 to 19, comprising a first auxiliary heat exchanger (36) disposed between the gas meter (2) and the inlet (4a) of the compressor (4) and configured to regulate the compressor inlet temperature (TB; TB1); optionally, the first auxiliary heat exchanger (36) is operatively connected to the heat exchange device (16).

21. The facility according to any one of claims 1 to 20, comprising a second auxiliary heat exchanger (37) disposed between the outlet (5b) of the expander (5) and the gas meter (2) and configured to regulate the gas meter inlet temperature (TG'); optionally, the second auxiliary heat exchanger (37) is operatively connected to the heat exchange device (16).

22. The facility according to any one of claims 1 to 21, comprising a regenerator (40) operatively operating between the gas meter (2) and the compressor (4; 4, 41) and between the gas meter (2) and the expander (5; 5, 43); the regenerator (40) also operatively connected to the thermal accumulator (9; 9a, 9b); the regenerator (40) being configured to exchange heat between the working fluid flowing through the thermal accumulator (9; 9a, 9b) and the working fluid entering the compressor (4; 4, 41) in the charging configuration or exiting the expander (5; 5, 43) in the discharging configuration.

23. The facility according to claim 22 when dependent on any one of claims 11, 12 or 13, wherein, The regenerator (40) is operatively inserted between the high-temperature first thermal accumulator (9a) and the low-temperature second thermal accumulator (9b); the regenerator (40) is configured to exchange heat between the working fluid flowing between the high-temperature first thermal accumulator (9a) and the low-temperature second thermal accumulator (9b) and the working fluid entering the compressor (4; 4, 41) in the charging configuration or leaving the expander (5; 5, 43) in the discharging configuration.

24. The facility according to any one of claims 11, 12, or 13, or according to claim 23, comprising: A second compressor (41) connected in series with the compressor (4) and a second expander (43) connected in series with the expander (5); wherein, the first thermal accumulator (9a) at high temperature operates operably between the compressor (4) and the second compressor (41) and also downstream of the second compressor (41) in the charging configuration; wherein, the first thermal accumulator (9a) at high temperature operates operably upstream of the second expander (43) and also between the second expander (43) and the expander (5) in the discharging configuration.

25. A method for energy management, comprising: A closed-loop thermodynamic cycle (TTC) is performed between a gas meter (2) and a mass accumulator (11) first in one direction during the charging phase and then in the opposite direction during the discharging phase. The gas meter (2) is used to store a working fluid in the gas phase at a first storage pressure (PAG') in equilibrium with atmospheric pressure, excluding atmospheric air. The mass accumulator (11) is used to store the working fluid in the liquid phase at a second storage pressure (PA'H). During the charging phase, the method stores heat and pressure, and during the discharging phase, the method uses the previously stored heat and pressure to generate energy. In the filling stage, the method includes: The working fluid is compressed to a final compression pressure (PC; PC2) higher than the critical pressure (Pcr) of the working fluid; the working fluid is cooled to a final cooling temperature (TE) close to the critical temperature (Tcr) of the working fluid by storing heat removed from the working fluid; the pressure of the working fluid is reduced to a decreasing pressure (PG) lower than the critical pressure (Pcr) of the working fluid; and the working fluid is stored in the mass accumulator (11) at a second storage pressure (PA'H) lower than the critical pressure (Pcr) of the working fluid and in equilibrium with the vapor phase of the working fluid itself; wherein, during the charging phase, the method further includes removing heat from the mass accumulator (11) to cause partial condensation of the vapor phase of the working fluid contained in the mass accumulator (11) and maintaining the second storage pressure (PA'H) in the mass accumulator (11) constant or substantially constant. In the emission stage, the method includes: The working fluid is pumped at a discharge pressure (PC') higher than the critical pressure (Pcr) of the working fluid, transferring previously stored heat to the working fluid and heating the working fluid, causing the working fluid to expand and storing the working fluid in the gas meter (2) at the first storage pressure (PAG'); wherein, during the discharge phase, the method further includes releasing heat to the mass accumulator (11) to cause partial evaporation of the liquid phase of the working fluid contained in the mass accumulator (11) and maintaining the second storage pressure (PA'H) in the mass accumulator (11) constant or substantially constant.

26. The method of claim 25, wherein, After cooling the working fluid to the final cooling temperature (TE) close to the critical temperature (Tcr) and before reducing the pressure of the working fluid to the reduced pressure (PG), the method includes, during the charging phase, removing heat from the working fluid to reduce and / or eliminate the vapor dryness of the working fluid at the end of the depressurization.

27. The method according to claim 25 or 26, wherein, Before pumping the working fluid, the method includes, during the discharge phase, removing heat from the working fluid to reduce the risk of cavitation that may occur during subsequent pumping.

28. The method according to any one of claims 25 to 26, wherein, During the filling phase, reducing the pressure of the working fluid includes: stacking the working fluid.

29. The method according to claim 28 when dependent on claim 26, wherein, Removing heat from the working fluid to reduce and / or eliminate the vapor dryness of the working fluid at the end of depressurization includes bringing the working fluid to a final depressurization temperature (TG) at the end of depressurization that is lower than the saturation temperature of the working fluid at the reduced pressure (PG).

30. The method according to any one of claims 25 to 26, wherein, During the filling phase, reducing the pressure of the working fluid includes subjecting the working fluid to auxiliary expansion.

31. The method according to claim 30 when dependent on claim 26, wherein, Removing heat from the working fluid to reduce and / or eliminate the vapor dryness of the working fluid at the end of depressurization includes: removing heat from the working fluid prior to assisted expansion, such that the working fluid remains in a subcooled liquid state during and at the end of assisted expansion.

32. The method according to any one of claims 25 to 31, wherein, Removing heat from the mass accumulator (11) and / or transferring heat to the mass accumulator (11) includes: exchanging heat directly or indirectly with the external environment.

33. The method according to any one of claims 25 to 32, wherein, Each of the operations of cooling the working fluid in the charging phase and heating the working fluid in the discharging phase is performed in two phases; wherein, in the charging phase, in a first phase, the working fluid is cooled to an intermediate temperature (TD) above the critical temperature (Tcr), and in a second phase, the working fluid is cooled from the intermediate temperature (TD) to the final cooling temperature (TE) close to the critical temperature (Tcr).

34. The method according to claim 33, wherein, The ratio of the intermediate temperature (TD) in Kelvin to the critical temperature (Tcr) in Kelvin is between 1.01 and 2.0, wherein the ratio of the final cooling temperature (TE) in Kelvin to the critical temperature (Tcr) in Kelvin is between 0.4 and 1.

1.

35. The method according to any one of claims 25 to 34, wherein, The final cooling temperature (TE) during the charging phase is greater than the pump discharge temperature (TC') during the discharge phase.

36. The method according to any one of claims 25 to 35, comprising: During the discharge phase, a portion of the heat from the expanded working fluid is transferred to the working fluid in a supercritical state before or during the heating of the expanded working fluid.

37. The method of claim 36, comprising: Excess heat from the transferred heat is released to the external environment.

38. The method according to any one of claims 25 to 37, comprising: During the filling phase, the temperature (TA) of the working fluid from the gas meter (2) before compression is adjusted.

39. The method according to any one of claims 25 to 38, comprising: During the discharge phase, the temperature (TF') of the expanded working fluid is adjusted before it enters the gas meter (2).

40. The method according to any one of claims 25 to 39, comprising: During the filling phase, a portion of the heat removed from the working fluid during cooling to the final cooling temperature (TE) is used to heat the working fluid prior to compression; And / or, during the discharge phase, a portion of the heat recovered from the expanded working fluid is used to further heat the working fluid after pumping and before expansion.

41. The method according to any one of claim 25 or 40, wherein, During the filling phase, compressing and cooling the working fluid includes: performing a first compression, followed by a first cooling, and then performing a second compression, followed by a second cooling, wherein at the end of the first compression, the working fluid is at a subcritical pressure (PC1), and at the end of the second compression, the working fluid is at a pressure (PC2) above the critical pressure (Pcr), wherein the temperatures (TC1, TC2) of the working fluid are similar or equal at the end of the first and second compressions.

42. The method according to any one of claims 25 to 41, wherein, During the discharge phase, heating and expanding the working fluid includes performing a first heating, followed by a first expansion, and then performing a second heating, followed by a second expansion.

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