PLANT AND METHOD FOR ACCUMULATION OF ENERGY IN THERMAL FORM

Abstract

A plant for the accumulation and transfer of thermal energy, which plant has an accumulation device of the kind with a bed of fluidizable solid particles. The plant further has for each accumulation device: electric resistor means arranged within the casing and thermally connected with the bed of particles, which electric resistors are configured for transmitting thermal energy generated by Joule effect to the particles and they are fed by exceeding electric energy from wind or photovoltaic source; and heat exchange means, also thermally connected with the bed of particles and which can be selectively actuated to receive thermal energy therefrom,
the overall configuration being such that the thermal energy is transferred from the resistor means to the fluidizable solid particles of the bed and from the fluidizable solid particles to the heat exchange means.

Claims

1. A plant for the accumulation of energy in thermal form, comprising an accumulation device, said accumulation device having: a containment casing; a bed of fluidizable solid particles received within said containment casing; heating means thermally connected with said bed of particles, which heating means is configured to transmit thermal energy to the fluidizable solid particles; and heat exchange means, also thermally connected to said bed and selectively activated to receive thermal energy therefrom, the overall configuration being such that said thermal energy is transferred from the heating means to the fluidizable solid particles and, in simultaneous or deferred manner, from said fluidizable solid particles to said heat exchange means, wherein the plant is configured to feed said heating means by means of excess electric energy or by means of residual thermal energy from industrial processes.

2. The plant according to claim 1, wherein said heating means is arranged within said containment casing and in contact with the fluidizable solid particles.

3. The plant according to claim 1, wherein said heating means comprises electric resistor means arranged within said containment casing and thermally connected with said bed of particles, which electric resistor means is configured to generate thermal energy by Joule effect and to transmit it to the fluidizable solid particles.

4. The plant according to claim 3, wherein said electric resistor means is arranged, at least partially, immersed in, or so as to be lapped by, said bed.

5. The plant according to claim 3, wherein said electric resistor means comprises one or more oblong elements extending longitudinally in an orthogonal direction to a free surface of said bed.

6. The plant according to claim 1, wherein said heating means and/or said heat exchange means have layers, or screens, of material resistant to high temperatures.

7. The plant according to claim 1, wherein said heating means is arranged externally to said casing.

8. The plant according to claim 7, wherein said heating means is thermally connected to a circuit of a fluidization gas of said fluidizable solid particles and configured to heat said gas before it enters said containment casing.

9. The plant according to claim 1, wherein said heating means comprises heat exchangers crossed, in use, by an operating fluid in liquid or vapor form.

10. The plant according to claim 1, wherein said heating means is part of a circuit of a heat pump device.

11. The plant according to claim 1, wherein said heat exchange means comprises one or more of the following components: thermoelectric elements; thermionic elements; thermo-photovoltaic elements; tube bundles configured to be crossed, in use, by an operating fluid.

12. The plant according to claim 1, wherein said containment casing has an irradiation opening configured to allow the entry of an incident solar radiation, so that said bed receives thermal energy from said incident solar radiation.

13. The plant according to claim 12, wherein said irradiation opening puts in direct communication an inner compartment of said containment casing with the external environment, being devoid, in use, of closing or shielding means.

14. The plant according to claim 12, wherein said irradiation opening is arranged at an upper wall of said containment casing, so that said bed of fluidizable solid particles, or a part thereof, is directly exposed, in use, to the incident solar radiation.

15. The plant according to claim 1, wherein said containment casing is closed with respect to the outside.

16. The plant according to claim 1, further comprising fluidizing means configured for introducing a fluidizing gas into said bed.

17. The plant according to claim 16, further comprising means for selectively varying the speed or the flow rate of the fluidizing gas.

18. The plant according to claim 16, wherein said fluidizing means is configured for an independent fluidization of selected parts of said bed.

19. The plant according to claim 1, comprising means for the production of electric energy arranged downwards of said accumulation device.

20. The plant according to claim 1, comprising a plurality of accumulation devices arranged thermally in series or in parallel to an operating fluid crossing the heat exchange means of each accumulation device.

21. A method for accumulating energy in thermal form, comprising: producing thermal energy by heating means arranged in thermal connection with a bed of fluidizable solid particles, which heating means is fed by means of excess electric energy or by means of residual thermal energy; accumulating thermal energy in said bed of fluidizable solid particles; and transferring the accumulated thermal energy to heat exchange means, for transforming the thermal energy of said fluidizable solid particles into electric energy or for transferring said thermal energy to the outside.

22. The method according to claim 21, further comprising a fluidization step of said fluidizable solid particles, which is activated under selected operating conditions.

23. The method according to claim 22, further comprising a selective adjustment of the speed or of the flow rate of a fluidizing gas.

24. The method according to claim 21, which provides an independent fluidization of selected parts of said bed.

25. The method according to claim 21, which provides a transfer of thermal energy from a hot fluidization gas outletting from the bed.

26. (canceled)

Description

BRIEF DESCRIPTION OF THE FIGURES

[0045] The figures of the enclosed drawings will be referred to, wherein:

[0046] FIG. 1 relates to a first preferred embodiment of a device for accumulating and transferring thermal energy of a plant according to the invention, which device comprises electric resistors inserted in a bed of fluidizable particles, in closed configuration and provided with thermionic, thermoelectric and/or thermo-photovoltaic components for the direct transformation of thermal energy into electric energy, by showing a schematic representation thereof in longitudinal section;

[0047] FIG. 1bis relates to a first embodiment variant of the device of FIG. 1, wherein in place of the resistors a heat pump is used;

[0048] FIG. 1ter relates to a second embodiment variant of the device of FIG. 1, wherein in place of the resistors heaters associated to a circuit for supplying fluidization gas are used;

[0049] FIG. 1quater relates to an embodiment variant of the device of FIG. 1ter, which provides heaters used to heat an operating fluid, for example air or water, flowing in suitable heat exchangers inserted into the bed of particles;

[0050] FIG. 2 relates to a second preferred embodiment of the device for accumulating and transferring thermal energy of a plant according to the invention, wherein to the configuration of FIG. 1 heat exchangers inserted into the bed of particles have been added, by showing a schematic representation thereof in longitudinal section;

[0051] FIG. 2bis relates to a preferred embodiment variant of the device of FIG. 1bis, wherein heat exchangers inserted into the bed of particles have been added, by showing a schematic representation thereof in longitudinal section;

[0052] FIG. 2ter relates to a preferred embodiment variant of the device of FIG. 1ter, wherein heat exchangers inserted into the bed of particles have been added, by showing a schematic representation thereof in longitudinal section;

[0053] FIG. 2quater relates to a preferred embodiment variant of the device of FIG. 1quater, wherein heat exchangers inserted into the bed of particles have been added, by showing a schematic representation thereof in longitudinal section;

[0054] FIG. 3 relates to a third preferred embodiment of the device for accumulating and transferring thermal energy of a plant according to the invention, which uses electric resistors, in open configuration and provided with thermionic, thermoelectric and/or thermo-photovoltaic components for the direct transformation of thermal energy into electric energy, by showing a schematic representation thereof in longitudinal section;

[0055] FIG. 3bis relates to the same embodiment variant of FIG. 2bis, in an alternative configuration of open type, by showing a schematic representation thereof in longitudinal section;

[0056] FIG. 3ter relates to the same embodiment variant of FIG. 2ter, in an alternative configuration of opened type, by showing a schematic representation thereof in longitudinal section;

[0057] FIG. 3quater relates to the same embodiment variant of FIG. 2quater, in an alternative configuration of open type, by showing a schematic representation thereof in longitudinal section;

[0058] FIG. 4 relates to a fourth preferred embodiment of the device for accumulating and transferring thermal energy of a plant according to the invention, wherein in the configuration of FIG. 3 heat exchangers inserted into the bed of particles have been added, by showing a schematic representation thereof in longitudinal section.

[0059] FIG. 4bis relates to the same embodiment variant of FIG. 1bis, in an alternative configuration of open type, by showing a schematic representation thereof in longitudinal section;

[0060] FIG. 4ter relates to the same embodiment variant of FIG. 1ter, in an alternative configuration of open type, by showing a schematic representation thereof in longitudinal section;

[0061] FIG. 4quater relates to the same embodiment variant of FIG. 1quater, in an alternative configuration of open type, by showing a schematic representation thereof in longitudinal section;

[0062] FIG. 5 shows a block diagram of an energy accumulation plant according to a preferred embodiment of the invention, which comprises accumulation devices according to anyone of the above-mentioned embodiments and embodiment variants, each one implementing a respective accumulation module, which plant is fed by renewable sources and inserted inside an existing thermoelectric power plant;

[0063] FIG. 6 shows a block diagram of a variant of the configuration of FIG. 5, wherein a turbine performing a steam re-superheating is inserted;

[0064] FIG. 7 shows a block diagram of an energy accumulation plant according to another preferred embodiment of the invention, which plant produces electric energy and comprises accumulation devices according to anyone of the above-mentioned embodiments and embodiment variants, each one implementing a respective accumulation module, which plant is fed by renewable sources and wherein said devices replace a traditional boiler;

[0065] FIG. 8 shows a block diagram of an energy accumulation plant according to an additional preferred embodiment of the invention, which plant produces thermal energy and comprises accumulation devices according to anyone of the above-mentioned embodiments and embodiment variants, each one implementing a respective accumulation module, which plant is fed by renewable sources; and

[0066] FIG. 9 shows a schematic representation of an accumulation plant lay-out according to a preferred embodiment of the invention, which comprises 50 modules each one based upon a respective accumulation device according to anyone of the above-mentioned embodiments and embodiment variants.

[0067] The sizes shown in the above-mentioned figures are to be meant as purely exemplifying and they are not necessarily represented proportionally.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0068] Embodiments and variants of the invention will be described hereinafter, and this with reference to the above-mentioned figures.

[0069] Analogous components are designated with the same numeral reference in the several figures.

[0070] In the following detailed description, additional embodiments and variants with respect to embodiments and variants already treated in the same description will be illustrated limited to the differences with respect to what already illustrated.

[0071] Moreover, the several embodiments and variants described hereinafter, as well as the relative components, means and elements, are likely to be used in combination.

[0072] With reference to FIG. 1, a device for accumulating and transferring thermal energy according to a first preferred embodiment of the invention is designated as a whole with 1.

[0073] The device is intended to be used in a plant provided with the function of accumulating and transferring thermal energy, in particular an electric and/or thermal energy production plant.

[0074] The device 1 first of all comprises a containment casing 2, which defines an internal compartment 20, the latter configured to house a bed 3 of fluidizable particles.

[0075] The casing 2 can have polygonal, for example cubic or parallelepiped, geometry. In the present example, the casing 2 has an upper wall 21, a side skirt 23 and a lower wall or base 24.

[0076] With respect to the geometry of the device 1, we can define a longitudinal direction L, in the present example vertical direction, and a cross direction T, orthogonal to the longitudinal direction L and in this example, then, horizontal direction.

[0077] The device 1 is here configured in closed form, that is it does not have openings towards the external environment and, preferably, it is thermally insulated with respect thereto.

[0078] The bed of fluidizable particles 3 is of granular type, that is formed by solid particles.

[0079] The preferred granular material type for the bed of particles of the device 1 has features of high capability, conductivity and thermal diffusivity.

[0080] The bed 3 occupies the internal compartment 20 so as to leave, even in use, a free space 22, or freeboard, above its own free surface 35. Particularly, the space 22 is limited on the lower side by the free surface 35, on the upper side by the wall 21 of the casing 2 and laterally by the skirt 23 of the casing itself.

[0081] The bed of particles 3 is preferably set in motion by fluidizing means, designated as a whole with 4 and configured to supply and distribute a fluidization gas, in particular air, through the same bed of particles 3. In the present embodiment, the means 4 comprises a plurality of elements for supplying or introducing fluidization air, arranged at the lower base 24 of the casing 2, that is the bed of particles 3.

[0082] The fluidization air path within the bed of particles 3 then is from bottom to top, in particular vertical or substantially vertical. In more general terms, the introduction of fluidization gas takes place according to the longitudinal direction L.

[0083] The fluidization gas coming from the bed of particles 3 is collected within the free area, or freeboard 22, and it is captured by suitable (not illustrated) extractor hoods placed on the upper wall 21.

[0084] Advantageously, means can be provided for selectively varying the speed and/or the flow rate of the fluidizing gas. In the same way, a selective and/or differentiated fluidization of parts of the bed of particles can be provided.

[0085] One or more electric resistors, or resistances, 7 are positioned inside the bed of particles 3, and preferably wholly immersed therein. In the present embodiment, they are introduced, by way of example, from the base of the bed of particles and they extend in longitudinal direction L.

[0086] Said resistors 7 are fed by means for the production of electric energy, for example of photovoltaic and/or wind type, and preferably they are protected by (not illustrated) screens resistant to high temperatures, such as for example layers of ceramic material.

[0087] In the free area, or freeboard 22, one or more heat exchange components 8 are housed, which can be connected to, or mounted on, the wall 21 of the casing 2. The heat exchange components 8 are thermally connected to the bed of particles 3 and can be activated by systems such as (not illustrated) electric switches. In the present example, advantageously the components 8 are of thermoelectric, thermionic, thermo-photovoltaic type or a combination thereof. The components 8 are configured for a direct transformation of thermal energy into electric energy and then they indeed convert the thermal energy of the bed of particles 3 into electric energy usable by users of any type.

[0088] The components 8 can be housed even inside the bed of fluidized particles 3, and then they are immersed into—or lapped by—the fluidized particles.

[0089] Even the components 8 are preferably protected by (not illustrated) screens resistant to high temperatures or abrasion, such as for example layers of ceramic material.

[0090] FIGS. 1bis, 1ter and 1quater show each one a respective embodiment variant of the device of FIG. 1, wherein the electric resistors 7 are replaced by different heating means or components of the bed of particles, indeed configured to convert an inlet energy, particularly electric energy, into heating thermal energy of the bed of particles 3.

[0091] In FIG. 1bis, inside of the bed of particles 3 heat exchangers 70 are positioned belonging to a circuit of a heat pump 71, the latter comprising a second exchanger 72, in contact with a low temperature source, a compressor 73 and a lamination valve 74.

[0092] In the variant of FIG. 1quater, the exchangers immersed into the bed of particles, designated with 70′, are part of a heat exchange circuit 71′ based upon the use of an operating fluid.

[0093] In FIG. 1ter, inside the circuit for supplying the fluidization gas, air heaters 700 are inserted which increase the temperature of the gas inletting the bed of particles 3, by allowing to increase the contained thermal energy thereof.

[0094] FIG. 2 relates to a second embodiment of the device according to the invention, herein designated with 1′. The device 1′ is different from that of the first embodiment and related variants as above described due to the fact of having further heat exchange elements housed within the bed 3, in particular tube bundles 5. Such tube bundles 5 can be crossed by an operating fluid, for example water in the liquid and/or steam state, and receive heat from the particles of the bed 3.

[0095] In particular, in the configuration of FIG. 2, the operating fluid outgoing from the device 1′ through the tube bundles 5, under conditions of design temperature and pressure, can be made to expand in a turbine 510 coupled to a generator for the production of electric energy or can be used for other industrial purposes, for example for the production of hot water, in conditioning systems or desalination plants. In other words, the tube bundles 5 are connected to further components of the plant wherein the device 1′ is inserted, for example one or more turbines 510, condensers 521, attemperators 530, intermediate heat exchangers 511, pumps 520 and so on, each one known on itself.

[0096] Embodiment variants can provide, as single components or heat exchange elements associated to the bed of particles 3, the tube bundles 5.

[0097] Similarly to the FIGS. 1bis to 1quater, FIGS. 2bis, 2ter and 2quater show each one a respective embodiment variant of the device of FIG. 2, wherein the electric resistors 7 are replaced by different heating means or components of the bed of particles, indeed configured to convert an inlet energy, particularly electric energy, into heating thermal energy of the bed of particles 3.

[0098] In FIG. 2bis, inside the bed of particles 3 heat exchangers 70 are positioned, belonging to a circuit of a heat pump 71, the latter comprising a second exchanger 72, in contact with a low temperature source, a compressor 73 and a lamination valve 74.

[0099] In the variant of FIG. 2quater, the exchangers immersed into the bed of particles, designated with 70′, are part of a heat exchange circuit 71′ based upon the use of an operating fluid.

[0100] In FIG. 2ter, inside the circuit for supplying the fluidization gas, air heaters 700 are inserted which increase the temperature of the gas inletting the bed of particles 3, by allowing to increase the thermal energy supplied thereby.

[0101] FIG. 3 relates to a third preferred embodiment of the device of the invention, herein designated with 100. With respect to the device described with reference to the first embodiment and relative above-illustrated variants, the device 100 has an irradiation opening 10 at the upper wall 21 of the casing 2. A (not illustrated) optical system, associated to the device 100, concentrates the incident solar radiation indeed inletting such opening 10 and within the compartment 20. In this way, the particles of the bed 3 absorb primary thermal energy, of solar origin.

[0102] In the present example, the opening 10 is shown as arranged at the upper wall 21 of the casing 2 and preferably centred longitudinally with respect thereto. Embodiment variants can provide a different positioning thereof. In the same way, the opening 10, under operating conditions, can be wholly open towards outside, without shielding or covering means, or it can have a protection window transparent to the incident solar radiation.

[0103] The herein considered configuration allows to accumulate thermal energy from the power supply of the electric resistors 7 or other already mentioned components and from the solar radiation concentrated through the irradiation opening 10.

[0104] FIG. 3 also shows a shaped confinement structure 80, or invitation, of the device 100, arranged at the mouth of the irradiation opening 10. The confinement structure 80 can develop wholly or mainly outside the device 100, that is it can or cannot project partially within the empty space 22.

[0105] The confinement structure 80 has a through-opening, that is it has tubular structure, so as to keep the direct communication between inside and outside of the casing 2 by means of the irradiation opening 10.

[0106] In an embodiment variant, the confinement structure 80 defines a calm chamber helping the freeboard 22 to avoid or reduce leakages of air and/or particles towards outside.

[0107] In the present embodiment variant, the confinement structure 80 has a tapered, in particular conical, shape with decreasing section towards inside of the casing 2. Such section of the confinement structure allows not to interfere with the direction of the solar radiation concentrated by the dedicated optical system.

[0108] Moreover, in the present embodiment variant the device 100 comprises an auxiliary device 9, arranged at the confinement structure 80 or, in general terms, of the irradiation opening 10. The auxiliary device 9 is constituted by thermoelectric and/or thermionic and/or thermophotovoltaic panels and it is configured so as to be directly exposed to the incident solar radiation for the generation of electric energy.

[0109] Alternatively, the device 9 is constituted by a heat exchanger apt to absorb directly the heat of the solar radiation by means of its own carrier fluid.

[0110] Similarly to what illustrated for the other embodiments, FIGS. 3bis, 3ter and 3quater show, each one, a respective embodiment variant of the device of FIG. 3, wherein the electric resistors 7 are replaced by several heating means or components of the bed of particles, indeed configured to convert an inlet energy, in particular electric energy, into heating thermal energy of the bed of particles 3.

[0111] In FIG. 3bis, inside the bed of particles 3 heat exchangers 70 are positioned belonging to a circuit of a heat pump 71, the latter comprising a second exchanger 72, in contact with a low temperature source, a compressor 73 and a lamination valve 74.

[0112] In the variant of FIG. 3quater, the exchangers immersed into the bed of particles, designated with 70′, are part of a heat exchange circuit 71′ based upon the use of an operating fluid.

[0113] In FIG. 3ter, inside the circuit for supplying the fluidization gas, air heaters 700 are inserted which increase the temperature of the gas inletting the bed of particles 3, by allowing to increase the contained thermal energy thereof.

[0114] With reference to FIG. 4, this illustrates schematically a fourth embodiment of the device of the invention, herein designated with 100′. Similarly to the configuration of FIG. 2, the device 100′ is different from the one described with reference to FIG. 3 due to the fact of having further heat exchange elements housed within the bed 3, in particular tube bundles 5. The configuration of said tube bundles and of further plant components associated thereto is the same already described above indeed with reference to FIG. 2.

[0115] The auxiliary device 9 can be independent from the heat exchange elements 5 immersed into the bed of particles or it can be connected thereto.

[0116] The FIGS. 4bis, 4ter and 4quater show each one a respective embodiment variant of the device of FIG. 4, wherein the electric resistors 7 are replaced by several heating means or components of the bed of particles, indeed configured to convert an inlet energy, particularly electric energy, into heating thermal energy of the bed of particles 3.

[0117] In FIG. 4bis, inside the bed of particles 3 heat exchangers 70 are positioned belonging to a circuit of a heat pump 71, the latter comprising a second exchanger 72, in contact with a low temperature source, a compressor 73 and a lamination valve 74.

[0118] In the variant of FIG. 4quater, the exchangers immersed into the bed of particles, designated with 70′, are part of a heat exchange circuit 71′ based upon the use of an operating fluid.

[0119] In FIG. 4ter, inside the circuit for supplying the fluidization gas, air heaters 700 are inserted which increase the temperature of the gas inletting the bed of particles 3, by allowing to increase the contained thermal energy thereof.

[0120] In the “open” configurations like those just described with reference to FIGS. 3-3quater and 4-4quater, the accumulation and transfer device can provide components of thermionic and/or thermoelectric and/or thermo-photovoltaic type, arranged outside the casing 2, for example around the irradiation opening 10, of the same type of the components 8 mentioned with reference to FIGS. 1 and 2 and configured for feeding the resistances 7 or the other heat exchange components introduced above with reference to the several embodiment variants.

[0121] A possible additional, not illustrated, configuration, of the invention device, both in “closed” and “open” form, provides that the transfer of thermal energy from the accumulation device takes place, alternatively or together with the described modes, by using directly the hot fluidization gas outgoing from the bed of particles. Such gas, wholly or partially used, is preferably dusted by cyclones or ceramic filters resistant to high temperatures, before it is sent to the downstream users.

[0122] As mentioned above, each one of the sofar described devices can be inserted in a plant configured for accumulating energy in thermal form. Some possible additional plant configurations are described hereinafter.

[0123] FIG. 5 shows a block diagram of a plant according to a preferred embodiment of the invention, which is designated as a whole with 200. The plant 200 comprises a plurality of devices according to anyone of the above-mentioned embodiments and embodiment variants, each one implementing a respective accumulation module. In the represented example, n accumulation devices, respectively designated with 210′, 210″, 210.sup.n are exemplified. Preferably, the above-mentioned devices are of the type without irradiation opening and then implemented, for example, according to the embodiment variants of FIGS. 1-1quater o 2-2quater. In the proposed configuration, it is provided that the thermal energy accumulated by the above-mentioned modules is used for the steam production.

[0124] The plant 200 is fed by renewable sources 400, which in figures are exemplified with a wind and a photovoltaic source, to exploit the exceeding electric energy thereof. In the herein considered embodiment, the plant is inserted inside, or it incorporates, an existing thermoelectric plant, in particular comprising a fossil fuel boiler 300 and a turbine belonging to a generation system or power block 202.

[0125] According to the demand from the grid, the plant 200 provides for the release of thermal energy by means of suitable heat exchangers, or heat exchange elements, included in each module, for the generation of steam to be sent to the generation system, or power block, 202, in this case already pre-existing in the plant, for the production of electric energy.

[0126] The plant 200 is managed by means of a control system, or unit, 201, which controls, in particular, the energy flows inletting the accumulation modules 210′-210.sup.n, the power block 202 and the energy supply to the grid (“grid”) 500.

[0127] In the herein exemplified configuration, the number of accumulation modules depending upon the area available for the plant in proximity of the generation group 202 can be so as to generate the same thermal power of the already existing boiler 300 or only a fraction thereof, by eliminating or reducing the consumption of the fossil fuel and the corresponding emission of CO.sub.2 in the environment.

[0128] The number of installed modules can be initially limited and subsequently increased to reach the same generation of thermal power of the boiler 300.

[0129] FIG. 6 shows a block diagram of a variant of the configuration of FIG. 5, wherein in the generation group 202 a turbine 230 is inserted, performing a steam re-superheating.

[0130] In the cycle of the plant variant exemplified in FIG. 6, the steam re-heating (“re-heating”) is provided, allowing an increase in the production effectiveness. Such re-heating is performed by means of additional accumulation modules designated with 211′-211.sup.n, of the type, too, already described with reference to the above-illustrated devices.

[0131] The set of the modular devices then is preferably divided into two sections, wherein the modules of both sections accumulate thermal energy by converting the electric energy from renewable sources 400. The produced steam, outgoing from the first section of modules 210′-210.sup.n is introduced in turbine 230 and, after a first expansion step, brought back to the other section of modules 211′-211.sup.n, for the steam re-heating which is then introduced again in the turbine 230.

[0132] In the represented configuration, a boiler with solid fuel 300 is however provided, integrating the steam superheating through two dedicated lines or sections 301 and 302.

[0133] FIG. 7 shows a block diagram of an energy accumulation plant according to another preferred embodiment variant of the invention. With respect to what already described in relation to FIG. 5, in the herein considered plant, the accumulation modules 210′-210n wholly replace the fossil fuel boiler.

[0134] FIG. 8 shows a variant of the scheme of FIG. 7, wherein the produced energy is used for thermal users 205. The herein considered plant, as for the preceding configurations, accumulates thermal energy by converting electric energy from renewable sources and transfers thermal energy depending upon the demand to connected thermal users.

[0135] FIG. 9 shows a schematic representation of a lay-out of accumulation plant according to a preferred embodiment of the invention, which comprises 50 modules, each one based upon a respective accumulation device according to anyone of the above-mentioned embodiments and embodiment variants. The modules accumulate thermal energy by converting electric energy from renewable sources and upon request produce electric energy by means of a dedicated generation group.

[0136] The modular system like the exemplified one is capable of reaching any required energy accumulation level by occupying due to its high power density small spaces for example 5 hectares—100 thermal modules—3000 MWh which by feeding a turbine having effectiveness of 40% is equal to 1200 electric MWh capable of feeding a city with 1,000,000 of inhabitants.

[0137] In all above-described preferred configurations, each accumulation module is provided with a system for tempering the produced steam to adapt the fluid temperature to the operating parameters of the connected users.

[0138] Moreover, as already said each plant configuration provides a control system which manages the steps for accumulating the thermal energy in the single module and, if needed, its release as such or under the form of electric energy.

[0139] In this context, additional co-generative configurations are possible for the combined production of electric energy and thermal energy.

[0140] As above illustrated, the possibility of accumulating huge amounts of thermal energy allows to use even existing fossil fuel power plants, instead of new suitably devised and constructed turbine/generator groups. The latter possibility can bring considerable economic and environmental advantages to the economy of the transition nowadays currently performed by the electric energy produced with fossil fuels to the electricity produced by renewable sources.

[0141] The invention further provides a method for accumulating and transferring thermal energy, based upon the functionalities already described above in relation to the plant of the invention.

[0142] The subject of the present invention has been sofar described with reference to preferred embodiments thereof. It is to be meant that other embodiments belonging to the same inventive core may exist, all belonging to the protective scope of the herebelow reported claims.