Electricity production process using a fuel cell

Abstract

The invention relates to a method for producing electricity (6) employing a fuel cell (1), in which the fuel (3) is produced by means of a thermal dissociation process applied to at least one of the products (7) of the cell (1), using heat (17, 19, 21) produced by at least one heat pump (13) electrically powered (14) by the cell (1). (Fig. 1)

Description

Title of the invention: Method for producing electricity using a fuel cell

[0001] The present invention relates to a method of electricity production using a non-galvanic fuel cell, and an installation for implementing this method.

[0002] As is known in itself, a non-galvanic fuel cell - referred to simply as a fuel cell in the following - makes it possible to produce electricity by the oxidation of the fuel supplied to it.

[0003] In the particular case of a hydrogen fuel cell, for example, the cell comprises an anode and a cathode separated by an electrolyte; hydrogen arrives at the anode, oxygen at the cathode, and the oxidation reaction of hydrogen by oxygen generates electric current, water and heat.

[0004] WO2023001779 teaches how, advantageously, one can produce a part of the fuel in a fuel cell by means of a thermal dissociation process using the heat produced by the cell.

[0005] The present invention aims to provide a process of this type enabling the production of all the fuel for the fuel cell.

[0006] This objective of the invention is achieved with a method of electricity production employing a fuel cell, in which the fuel is produced by means of a thermal dissociation process applied to at least one of the products of the cell, using heat produced by at least one heat pump electrically powered by the cell.

[0007] The cumulative use of the heat produced by the heat pump can generate a sufficient quantity of fuel, and thus make the process self-sufficient in fuel consumption.

[0008] According to other optional features of the process according to the invention, taken alone or in combination:

[0009] - the heat produced by the fuel cell is also used to put implementing the said thermal dissociation process: the use of this additional heat makes it possible to increase the quantity of fuel produced;

[0010] - the heat produced by one or more elements of the device is also used to provide so-called cogeneration heat to the users of the process;

[0011] - said dissociation process comprises a series of chemical reactions endothermic;

[0012] - said dissociation process comprises at least one electrolysis step and a portion of the electricity from said battery is used to power this electrolysis reaction;

[0013] - a portion of the heat produced by said heat pump and / or by is recovered said battery to directly produce electricity while lowering the temperature of the heat to a level required by one of the chemical reactions;

[0014] - hydrogen is used as a fuel, and the water produced by The fuel cell uses the following series of reactions in the iodine / sulfur cycle to dissociate water: 2 H2SO4^ 2 SO2 + 2 H2O + O2 HI I2 + H2 I2 + SO2 + 2 H2O → 2 HI + H2SO4

[0015] - the reaction HI —> I2 + H2 is carried out with a proton exchange membrane battery operating between 50°C and 100°C, for example 80°C.

[0016] The present invention also relates to an installation for implementing the aforementioned process, comprising a fuel cell, at least one heat pump, and at least one unit for producing said fuel thermally connected to said heat pump, capable of receiving said product from the cell and dissociating it to produce said fuel.

[0017] Preferably, said fuel production unit is also thermally connected to said fuel cell.

[0018] Other features and advantages of the invention will become apparent from the following description, with reference to the accompanying figures, which illustrate:

[0019] [Fig-1]: an electricity production installation implementing a first embodiment of the process according to the invention;

[0020] [Fig.2]: an electricity production installation implementing a second embodiment of the process according to the invention.

[0021] For clarity, identical or similar elements are identified by identical or similar reference signs throughout the figures.

[0022] In what follows, we will illustrate the invention with a fuel cell in which the fuel is hydrogen, but it should be clearly understood that the principles of the invention can be applied to other types of fuel cells.

[0023] Referring to the first embodiment illustrated in [Fig.1], a hydrogen fuel cell is shown, in which the fuel is hydrogen 3, oxidized by oxygen 5 within an electrolytic system, as mentioned in the preamble to this description.

[0024] This oxidation reaction allows the flow of electrons between the anode and the cathode of the electrolytic system, and thus the production of electricity 6.

[0025] This oxidation reaction also has the effect of producing water 7 and releasing a significant amount of heat 9, typically reaching a temperature of around 830°C.

[0026] As taught by WO2023001779, the heat 9 released by the hydrogen fuel cell can be recovered to produce hydrogen in a series of reactors 11 using a cascade of endothermic chemical reactions, such as the iodine / sulfur cycle reactions mentioned above, or the bromine / sulfur cycle reactions, or the chlorine / sulfur cycle reactions, or reactions using an alkali metal hydride, or reactions using iron(III) chloride and iron(II) chloride, or vanadium chloride and vanadium tetrachloride.

[0027] In the context of the present invention, at least one heat pump 13 is provided, powered by a portion of the electricity 14 produced by the hydrogen fuel cell 1.

[0028] This heat pump 13 is used to raise the temperature of a cold source 15 (typically around 20°C but also potentially hotter, for example 80°C) such as ambient air, river water, sea water or water from a geothermal installation, to the different temperatures 17, 19, 21 required to carry out the endothermic reactions for the production of hydrogen in the reactors.

[0029] The term "heat pump" used in the context of the present invention may refer to a plurality of heat pumps and / or a heat pump comprising a plurality of cascaded cycles in which the compressible gases operate at temperatures below their critical temperatures and above their boiling points.

[0030] For example, gaseous mercury, water vapor and chlorine can be used as heat pump gases.

[0031] For example, when using the iodine / sulfur cycle to produce hydrogen, heat transfer fluids at respective temperatures of 830°C, 650°C and 120°C can be circulated between the heat pump 13 and the different reactors 11, allowing the following three endothermic reactions of dissociation of the water 7 supplied by the fuel cell 1 to be carried out respectively:

[0032] 2 H2SO4^ 2 SO2 + 2 H2O + O2 HI I2 + H2 I2 + SO2 + 2 H2O → 2 HI + H2SO4

[0033] By recovering the heat 17, 19, 21 generated by the heat pump 13, sufficient energy is provided to generate the quantity of hydrogen 3 necessary for autonomous operation of the hydrogen cell 1, that is to say, an operation not requiring the external supply of fuel.

[0034] By also recovering the heat 9 generated by the hydrogen cell 1, to generate hydrogen 3, we can reduce the share of electricity taken from the production of the fuel cell for the thermochemical production of hydrogen.

[0035] In some cases it may be necessary to use the heat 9 released by the cell 1 so that the quantity of hydrogen produced by the thermochemical reactions is sufficient for the operation of the cell.

[0036] In the second embodiment illustrated in [Fig.2], the water dissociation reactions include on the one hand endothermic chemical reactions, and on the other hand at least one electrolysis reaction.

[0037] More specifically, a five-stage cycle using copper and chlorine can be used, as described in the article "Energy analysis of heat exchangers in the copper-chlorine thermochemical cycle to enhance thermal effectiveness and cycle efficiency", published in the "International Journal of Low-Carbon Technologies", Volume 6, Issue 3, September 2011

[0038] The five steps E1 to E5 of this cycle are as follows: [Tables 1] Steps Energy source Reaction temperature Reactions El heat 400°C 2CuC12(s) + H2O(g) -> CuO-CuCl2(s) + 2HC1(g) E2 heat 500°C CuO-CuCl2(s) -> 2CuCl(l) + l / 2O2(g) E3 electricity 25-80°C 4CuCl(s) + H2O -> 2CuCl2(aq) + 2Cu(s) E4 heat >100°C CuCl2(aq) -> CuCl2(s) E5 heat 430-475°C 2Cu(s) + 2HCl(g) -> 2CuCl(l) + H2(g)

[0039] The reaction in step E3 is electrolytic in nature, and therefore requires an input of electricity.

[0040] Advantageously, this input is taken 23 from the electricity produced by the hydrogen fuel cell 1.

[0041] With regard to the endothermic chemical reactions of the steps E1, E2, E4 and E5, the reaction temperatures 19, 24, 17, 21 required respectively of 400°C, 500°C, 120°C and 430°C, are provided by heat transfer fluids circulating between the heat pump 13 and the hydrogen production reactors 11 3 in which these different reactions take place.

[0042] Advantageously, a heat engine (not shown) can be used to lower the temperature emitted by the hydrogen fuel cell from 830°C to 500°C in order to implement in particular the aforementioned step E2, this heat engine making it possible to provide an additional source of electricity production.

[0043] According to a variant of this second embodiment, the aforementioned iodine / sulfur cycle can be used to produce hydrogen, but the HI —> I2 + H2 step can be carried out using a proton exchange membrane cell operating between 50°C and 100°C, for example at 80°C.

[0044] Such a membrane fuel cell can operate by taking part of the electricity produced by the hydrogen fuel cell 1.

[0045] Such a membrane cell includes a catalyst at its electrodes, such as platinum or cerium gadolinium oxide (CGO) Ceo.gGdo.iOi^ developed in particular by the company Cres Power Ltd.

[0046] As will be understood from the foregoing, the method and installation for electricity production according to the invention make it possible to operate a fuel cell autonomously, that is to say without external fuel input.

[0047] This autonomy is obtained by combining the quantities of heat produced by the fuel cell itself, and by at least one additional heat pump: these quantities of heat, enabling the implementation of endothermic chemical reaction cycles, possibly associated with an input of electricity enabling the implementation of electrolytic reactions, provide enough energy to produce the fuel for the fuel cell without external input.

[0048] Naturally, the invention is described above by way of example. It is understood that a person skilled in the art is able to carry out different embodiments of the invention without departing from the scope of the invention.

[0049] In particular, the invention covers a process and an installation in which the heat enabling the reactions to be carried out in the fuel production unit 11 could come only from the heat pump 13 - and therefore not from the fuel cell 1.

Claims

Demands

1. Method of producing electricity (6) employing a fuel cell (1), wherein the fuel (3) is produced by means of a thermal dissociation process applied to at least one of the products (7) of the cell (1), using heat (17, 19, 21; 24) produced by at least one heat pump (13) raising only the temperature of a cold source (15), electrically powered (14) by the cell (1).

2. A method according to claim 1, wherein the heat (9) produced by the fuel cell (1) is further used to implement said thermal dissociation method.

3. A process according to any one of claims 1 or 2, wherein said dissociation process comprises a succession of endothermic chemical reactions.

4. A method according to any one of the preceding claims, wherein said dissociation method comprises at least one electrolysis step, and a portion (23) of the electricity from said battery (1) is used to power this electrolysis reaction.

5. A method according to any one of the preceding claims, wherein a portion of the heat produced by said heat pump and / or by said battery is recovered to directly produce electricity.

6. A process according to any one of the preceding claims, wherein hydrogen (3) is used as the fuel, and the following series of reactions from the iodine / sulfur cycle are applied to the water (7) produced by the fuel cell (1) to dissociate the water: 2 H2SO4 → 2 SO2 + 2 H2O + O2 → HI I2 + H2 I2 + SO2 + 2 H2O → 2 HI + H2SO4

7. A method according to claim 6, wherein the reaction HI —> I2 + H2 is carried out with a proton exchange membrane cell operating between 50°C and 100°C, for example at 80°C.

8. An installation for implementing a method according to any one of the preceding claims, comprising a fuel cell (1), at least one heat pump (13) solely raising the temperature of a cold source (15), and at least one unit (11) for producing said fuel (3) connected

9. thermally to said heat pump (13), capable of receiving said product (7) from the cell (1) and of dissociating it to produce said fuel (3). Installation according to claim 8 for the implementation of a process according to claim 2, wherein said fuel production unit (11) (3) is further thermally connected to said fuel cell (1).

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