CA2211391A1 - An electrochemical energy conversion and storage system - Google Patents
An electrochemical energy conversion and storage systemInfo
- Publication number
- CA2211391A1 CA2211391A1 CA002211391A CA2211391A CA2211391A1 CA 2211391 A1 CA2211391 A1 CA 2211391A1 CA 002211391 A CA002211391 A CA 002211391A CA 2211391 A CA2211391 A CA 2211391A CA 2211391 A1 CA2211391 A1 CA 2211391A1
- Authority
- CA
- Canada
- Prior art keywords
- energy
- cell
- energy storage
- gas
- steam
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
- C01B3/06—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen, e.g. water, acids, bases, ammonia, with inorganic reducing agents
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
- C01B3/06—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen, e.g. water, acids, bases, ammonia, with inorganic reducing agents
- C01B3/061—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen, e.g. water, acids, bases, ammonia, with inorganic reducing agents by reaction of metal oxides with water
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/01—Products
- C25B1/02—Hydrogen or oxygen
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
- C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/06—Combination of fuel cells with means for production of reactants or for treatment of residues
- H01M8/0606—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/06—Combination of fuel cells with means for production of reactants or for treatment of residues
- H01M8/0606—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants
- H01M8/0656—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants by electrochemical means
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/18—Regenerative fuel cells, e.g. redox flow batteries or secondary fuel cells
- H01M8/184—Regeneration by electrochemical means
- H01M8/186—Regeneration by electrochemical means by electrolytic decomposition of the electrolytic solution or the formed water product
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
- H01M8/241—Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported electrolytes
- H01M8/2425—High-temperature cells with solid electrolytes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
- H01M8/241—Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported electrolytes
- H01M8/2425—High-temperature cells with solid electrolytes
- H01M8/243—Grouping of unit cells of tubular or cylindrical configuration
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
- H01M2008/1293—Fuel cells with solid oxide electrolytes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0065—Solid electrolytes
- H01M2300/0068—Solid electrolytes inorganic
- H01M2300/0071—Oxides
- H01M2300/0074—Ion conductive at high temperature
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
- Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
Abstract
An apparatus for and a method of storing electrical energy as chemical energy and recovering the electrical energy from stored chemical energy by operating an electrochemical cell in two modes, such as a high temperature, solid oxide electrolyte electrochemical cell, in an energy storage mode and an energy recovery mode, is characterized by the steps, in an energy storage mode, of:
(A) supplying external electrical energy to electrical leads, and H2O (steam) gas to a cathode of at least one electrochemical cell (56) operating as an electrolysis cell using a solid oxide electrolyte (60) between two electrodes (58 and 62), the electrolysis cell operating to produce H2 gas and O2 gas; (B) passing the H2 gas into an energy storage bed reactor (88) containing iron oxide (90), to produce iron metal (Fe) in the energy storage reactor and H2O
(steam); (C) recirculating the H2O (steam) to the electrolysis cell to be electrolyzed; and, (D) repeating steps (A to C) until substantially complete conversion of iron oxide to iron metal, for chemical energy storage of electrical energy; and, further characterized by the steps, in an energy recovery mode, of: (E) supplying H2O (steam) gas to the energy storage bed reactor (88) containing iron metal (Fe) (90) to produce iron oxide (FeO) in the energy storage reactor and H2 gas; (F) passing the H2 gas to an electrode of at least one electrochemical cell operating as a fuel cell and supplying O2 gas or air to the other electrode to produce electrical energy and H2O
(steam); (G) recirculating the H2O (steam) produced to the energy storage bed reactor (88); (H) repeating steps (E to G) until substantially complete conversion of iron metal to iron oxide and H2 gas for electrical energy recovery from chemical energy storage; and, (I) recovering the electrical energy produced.
(A) supplying external electrical energy to electrical leads, and H2O (steam) gas to a cathode of at least one electrochemical cell (56) operating as an electrolysis cell using a solid oxide electrolyte (60) between two electrodes (58 and 62), the electrolysis cell operating to produce H2 gas and O2 gas; (B) passing the H2 gas into an energy storage bed reactor (88) containing iron oxide (90), to produce iron metal (Fe) in the energy storage reactor and H2O
(steam); (C) recirculating the H2O (steam) to the electrolysis cell to be electrolyzed; and, (D) repeating steps (A to C) until substantially complete conversion of iron oxide to iron metal, for chemical energy storage of electrical energy; and, further characterized by the steps, in an energy recovery mode, of: (E) supplying H2O (steam) gas to the energy storage bed reactor (88) containing iron metal (Fe) (90) to produce iron oxide (FeO) in the energy storage reactor and H2 gas; (F) passing the H2 gas to an electrode of at least one electrochemical cell operating as a fuel cell and supplying O2 gas or air to the other electrode to produce electrical energy and H2O
(steam); (G) recirculating the H2O (steam) produced to the energy storage bed reactor (88); (H) repeating steps (E to G) until substantially complete conversion of iron metal to iron oxide and H2 gas for electrical energy recovery from chemical energy storage; and, (I) recovering the electrical energy produced.
Description
W 096123322 PCT~US96/00648 AN ELECTROCHEMICAL ENERGY CONVERSION AND STORAGE SYSTEM
The invention relates to the field of energy conversion and storage in electrical power plant operations during off-peak power plant operations. More particularly the invention relates to elecll~rllf....i~l cells, such as a high ~ dture, solid oxide dectrolyte fuel cells ~.,.dted in an electrolysis mode, used for converting electrical energy to ch~o~nir~l energy in the form of hydrogen gas, which converts iron oxide to met~l, thereby forming compactly stored chemical energy, and the stored chrnlir~l energy can later be reconverted via hydrogen into electrical energy in electroçhPmic ~l fuel, such as high le"~pe~dture, solid oxide electrolyte fuel cells operated in a fuel cell mode.
Even more particularly, the invention is directed to an apparatus for and a method of converting and storing of electrical energy in the form of chPmic~l potential energy during off-peak electrical power plant operations by the following operations:
electrolyzing H20 (steam) to H2 and ~2 in an electroc hetnic~l electrolysis cell operating on electrical energy supplied from an external source; passing the H2 produced through 15 a storage reactor bed of iron oxide (FeO) that is thermally coupled to a heat source, wherein the iron oxide (FeO) is reduced to iron metal (~;e) to form stored chemir~l potential energy for extended periods; later, when elrctric~l energy is called for, passing H2O (steam) through the storage reactor bed, wherein the iron metal (Fe) is oXi~li7f'd to FeO and chemical potential energy is recovered as H2; and then oxidizing 20 the H2 recovered in an electrochemir~l fuel cell to generate electrical energy for tr~ncmi.c.cion .
W O 96/23322 PCTrUS~G/OCC~18 Base load power plants such as nuclear power plants and combustion-thermal power plants are preferably operated under a constant load. Peak power electrical energy requirements are basically undesirable from a standpoint of highly efficient generation of electrical energy, but must be met on a daily and seasonal routine. Peak S power electrical energy demand per-~li7es power generation f~cilities basically in the form of increased capital cost and generally higher fuel cost. To make additional electrical power capacity available during peak demand periods, higher than required capacity usually exists during off-peak periods which therefore requires energy storage systems.
The periods of low power demand, thus, leave the base load power plant operating under less than optimal conditions and excess power generation capacity is available during such periods. It is very desirable in this in~t~nce to store electrical energy efficiently and at low costs, and many schemes have been proposed for such energy storage f~rilitirs For example, "pumped hydro" and "co~ r~s~d air" energystorage systems have been used. These systems store energy in the form of potential energy during off-peak hours and return the energy to the power group during peak power ~lem~ncl periods. Such practical sch~mrs are depçn-lent on geography and geology and require ci~nific~nt space, and, therefore, the siting of such energy storage f~r.ilitirs is not flexible enough for wide-spread applications.
Electrochemir~l energy storage systems however would have distinct advantages over other systems. Electroch~omir~l energy storage systems are highly compact because chemic~l energy can be stored in a small volume. For this reason, it can be modular in construction. It also has a potential for being the most energy efficient method for storage of electrical energy since the energy conversion of electrical to merh~nir~l and back to electrical energy is avoided.
High temperature, solid oxide electrolyte fuel cells and multi-cell generators and configurations thereof designed for converting chemic~l energy into direct current electrical energy at temperatures typically in the range of 600~C to 1200~C are well known and taught, for example, in U.S. Patent Specification Nos. 4,395,468 (Isenberg) and 4,490,444 (Isenberg). These high le.,l~ef~ture, solid oxide electrolyte fuel cells are known to operate in two modes, namely in an electrochemical power generation mode using gaseous fuel such as hydrogen or carbon monoxide derived from reformed hydrocarbons, coal, or the like, which is converted to direct current electrical energy, and in an electrochemical power usage mode using steam and carbon dioxide which is converted via electrolysis into oxidizable fuels such as hydrogen or carbon monoxide, S lespeclively. This capability of the high te".~elaL.lre, solid oxide electrolyte fuel cells is unique among fuel cell types and is due to the fact that the solid oxide electrolyte fuel cells are solid state devices which operate in a te"-l,eldL.lre range of about 600~C to 1200~C. At these temperature levels, the thermal energy is high enough that electrolysis can proceed without using noble metal catalysts at the electrodes, and the 10 laws of thermodynamics predict, and are confirmed by experiment, a reduced electrical power requirement for electrolysis as compared to low ~ ,dture electrochemit~l batteries. For example, sodium-sulfur batteries that operate at about 350~C have been investi~t.od for use in storing off-peak electrical energy.
Producing fuels, such as hydrogen fuel gas, by electrolysis is a basic 15 re~uirement for an electrochemical energy conversion and storage system. The energy storage in the form of hydrogen fuel gas through the electrolysis of steam, however, would re~uire bulky gas storage f~rilitilos and would restrict the siting of this type of energy conversion and storage system. Therefore, there is a need to convert the bulky hydrogen energy carrier into another form of energy carrier which is not bulky and can 20 be stored in a compact arrangement. At the a~ "iale demand time, this potential energy can be called into service by reconversion to hydrogen as a fuel to a fuel cell generator to generate electrical energy.
What is needed is an efficient and compact method of storing electrical energy in the form of cherni~l energy that is relatively compact and can be stored indefinitely 25 for later reconversion to electrical energy for electrical power tr~nsmicsion.
It would be advantageous and it is an object of the invention to derive an energy storage and conversion system from high L~ e-dture, solid oxide electrolyte fuel cells operating in two modes, that is 1. an electrolysis mode for electrical energy storage and 2. a fuel cell mode for electrical energy recovery, using iron metal and iron oxide 30 (Fe/FeO) beds as the energy storage mediums.
W 096/23322 PCTrUS96/00648 It is another object of the invention to provide an energy conversion and storage system by storing electrical energy as chemical energy by the electrolysis of H2O
(steam) in a high temperature, solid oxide electrolyte electrolysis cell for H2 production and subsequent storage of this chemical energy in the form of Fe metal, by reduction 5 of FeO with H2 in a storage reactor bed, and later by converting the stored chemical energy to electrical energy by the reaction of H2O (steam) with the Fe in the storage reactor bed for H2 gas production and subsequent use of the H2 gas produced in the high ~e~ dture, solid oxide electrolyte fuel cell generator as fuel to generate and recover electrical energy.
These and other objects of the invention are accomplished by a method of storing electrical energy as chemical energy and recovering the electrical energy from the stored che~ l energy by operating an electrochPmi/~.~l cell in two modes, anenergy storage mode and an energy recovery mode, characterized by the steps in an energy storage mode of: (A) supplying external electrical energy to electrical leads and H20 (steam) gas to a c~thode of at least one electrocht~mic~l cell operating as an electrolysis cell using a solid oxide electrolyte between an anode and the cathode, the electrolysis cell ope.ating at a lt;lllpe,dture of between 600~C and 1000~C, to produce H2 gas along the cathode and ~2 gas along the anode; (B) passing the ~2 gas produced along the cathode of the electrolysis cell into a energy storage reactor containing iron oxide operating at a temperature of between 600~C to 800~C, and produce iron metal in the energy storage reactor and H2O (steam); (C) recirculating the H2O (steam)produced in the energy storage reactor to the cathode of the electrolysis cell to be electrolyzed; and, (D) repe~;ng steps (A) to (C) until subst~nti~lly complete conversion of iron oxide to iron metal, for chemic~l energy storage of electrical energy; and, further characterized by the steps in an energy recovery mode of: (E) supplying H20 (steam) gas to the energy storage reactor co~ ining iron metal operating at a temperature of between 600~C and 800~C, to produce iron oxide in the energy storage reactor and H2 gas; (F) passing the H2 gas to a fuel anode of the at least one electrochemic~l cell operating as a fuel cell and supplying ~2 gas or air to an air cathode of the at least one electrochemical cell operating at a temperature of between 600~C and 1200~C, to conduct electrical energy along the external leads and produce CA 022ll39l l997-07-24 W O 96/23322 PCTrUS9GJC~'18 H2O (steam) along the fuel anode; (G) recirculating the H2O (steam) produced at the fuel anode of the fuel cell to the energy storage bed; (H) repeating steps (E) to (G) until substantially complete conversion of iron metal (Fe) to iron oxide and H2 gas for electrical energy recovery from chernir~l energy storage; and, (I) recovering the 5 electrical energy produced.
The invention also resides in an electrochemical energy conversion and storage device operational in two modes, an energy recovery mode and an energy storage mode that is characterized by: (A) an electrochemical cell chamber, the cell chamber con~ining at least one electrochemical cell bundle, the cell bundle containing a plurality 10 of parallel, axially elongated, interconnected electrochemi~l cells, each cell including a porous exterior electrode, a porous interior electrode, and a gas-tight solid oxide electrolyte between the two electrodes; (B) a combustion çh~mber connected to the cell ch~mher; (C) at least one combustion eYh~l~st ch~nn~l connPct~ from the combustion chamber to the atmosphere; (D) at least one energy storage chamber connected to the 15 cell chamber, the energy storage chamber con~illitlg either iron oxide in the energy storage mode of operation or iron metal in the energy recovery mode of operation; (E) at least one recirculation gas çh~nnel connPct~ from outside of the porous exterior electrode in the cell cll~mb~-r to the energy storage chamber; (F) a steam inlet connected to the outside of the porous exterior electrode in the cell chamber; (G) an oxidant inlet 20 connected to the inside of the porous interior electrode in the cell chamber; and, (H) electrical leads connected from the cell bundles in the cell chamber to an external circuit, in which the device can be o~eiated in an energy storage mode by supplying direct current electrical energy from the external circuit through the leads to the electroc~l~mic~l cells and steam through the steam inlet to the porous exterior electrode 25 and providing the energy storage chamber in the iron oxide state, and in which the device can be operated in an energy recovery mode by providing the energy storage chamber in the iron state and supplying steam through the steam inlet to the energy storage chamber and an oxidant through the oxygen inlet to the porous interior electrode ~ and recovering direct current electrical energy from the electrochemical cells through 30 the leads to the external circuit.
W 096/23322 PCT~US~C~'CAC~8 There exist several iron oxide compositions, such as FeO, Fe,03, Fe30,. For simplicity we name here only FeO, since it is in chernic~l equilibrium with iron (Fe).
However the formation of the other oxides of iron in the scheme of the invention is not excluded.
There are shown in the drawings certain exemplary embodiments of the invention as presently preferred. It should be understood that the invention is not limited to the embodim~nh fli~;close~l as examples, and is capable of variation within the scope of the appended claims. In the drawings:
FIGURE 1 is a schematic of the electrical energy storage and conversion system of the invention being operated in the energy storage mode, FIGURE 2 is a schematic of the electrical energy storage and conversion system of the invention being operated in the energy recovery mode, FIGURE 3, which best illustrates the invention, is a sectional view of an exempl~ry electrical energy storage and conversion system of the invention which can be operated in an energy storage mode and an energy recovery mode, and FIGURE 4 is a graph of the cell voltage characteristics on charge and discharge of the electrical energy storage and conversion system of the invention.
The term "electrolysis cathode" and "fuel anode" as used herein means that electrode in contact with a hydrogen species such as H2O (steam), H2 gas, or hydroc.~bon fuel, such as natural gas. The term "electrolysis anode" and "oxidant c~tho~le" as used herein means that electrode in contact with an oxygen species, such as ~2 or air. The term "spent" as used herein means partially reacted or depleted according to the electrochemical equations described herein. The term "combustedexhaust gas" as used herein means a combusted mixture of hydrogen or fuel with oxidant or air. The term "iron oxide" as used herein includes several iron oxidecompositions, such as FeO, Fe,03, and Fe304. For simplicity, we name only FeO, since it is in chemical equilibrium with iron (Fe). However, the formation of other oxides of iron in the scheme of the invention is not excluded.
Referring now to Figure 1, an electrochelniç~l electrolysis cell apparatus 1 operated in an energy storage mode is shown, cont~ining at least one axially elongated, tubular electrochemical electrolysis cell l0, such as high telnpe,at~lle, solid oxide W O 96123322 PCT~US~6100CS8 electrolyte electrolysis cell. It should be recognized that a plurality of electrolysis cells 10 can be interconnectP~ in series and/or parallel arrangement as is well known in the art and used. It should also be recognized that the foregoing description of thepreferred tubular configuration is merely exelnpl~ry and should not be considered limitin~ in any manner. It is possible that other configurations for the electrolysis cell could be used, for example, flat plate configurations. Each tubular electrolysis cell 10 has an exterior porous electrode or electrolysis cathode 12, an interior porous electrode or electrolysis anode 16, and a gas-tight solid oxide electrolyte 14 between theelectrodes, as is well known in the art. It should further be recognized that the location of the anode and cathode can be inverted.
The electrolysis cell 10 is intenderl to operate at elevated le~ e~atures, over about 600~C to 1200~C, and typically in the l~"~peldture range of about 650~C to1200~C, preferably about 800~C to about 1000~C. The cell telllpel~ re is m~int~in~od by ohmic r~ t~ce losses or better by heat exçh~nge with other sources of heat energy.
The ~,eI~"ed configuration is based upon an electrolysis cell system, in energy storage mode wherein at te",~e~dtures of about 800~C to 1000~C, an incoming H2O (steam) is directed axially over the outside of the electrolysis cell 10 and a direct current of electrical energy produced from an electrical power plant (converted by conventional methods from AC to DC current prior to being supplied to the electrolysis cell) is directed through an external load circuit (not shown) by electrical leads 18 to the electrolysis c~tho~le 12. During operation, water (steam) molecules are fed to the electrolysis cathode 12 and pass through the porous cathode and electrochemi~lly react at the solid oxide electrolyte 14/cathode 12 interface, to produce hydrogen gas which exits the electrolysis cell 10 at the ç~thode. Oxygen ions pass through the solid electrolyte 14 and are then electrochemically oxidized at the solid oxide electrolyte 14/anode 16 interface, to produce oxygen gas which exits the electrolysis cell at the anode and is vented to the atmosphere as a by-product of energy storage or recovered, if possible.
~ The electrochernic~l reactions in the electrolysis cell are according to Equations (2), (3) and (4).
W 096/23322 PCT~US96/00648 cathodç:2H2O + 4e- = 2O2- + 2H2 (2) anode: 2O2- = 4e~ + ~2 (3) overall: 2H2O = 2H2 + ~2 (4) S The hydrogen gas (H2) produced during electrolysis of steam exits the electrolysis cell 10 and passes through at least one iron/iron oxide (Fe/FeO) storage reactor bed 20 collt~ini.~ compacts of iron oxide (FeO) operating at te~ )e-dtures of about 600~C to 800~C, to produce compacts of iron metal (Fe) and water (steam). It should be recognized that a plurality of connected storage reactor beds can be used.
The energy storage reaction is rep.ese.lted by Equation (5).
FeO + H2 = Fe + H2O (S) The water vapor produced recirculates and passes again and again to the cathode 12 of the electrolysis cell 10 until subsl~nt;~lly all of the FeO is reduced to Fe. Due to the c~thode gas recirculation, a very small amount of hydrogen/steam is required for the subst~nti~lly complete reduction of a large amount of FeO to Fe via the energy storage mode. When all the FeO in all the Fe/FeO beds 20 is reduced to Fe, the energy storage capability is e~th~tlcte~.
Since the anode 16 and cathode 12 co..,palL-nents of the electrolysis cell l0 are not absolutely hermetiç~lly sealed against each other, some H2 may be lost to the anode side 16 through two porous barrier boards 22 and 24 which results in an overall system energy loss. In this arrangement, the spent anode and cathode gases as well as anode and cathode co-~ nents are separated from each other through high temperature, porous ceramic fiber boards, such as porous ~lumin~ boards (not shown). The absence of rigid seals between electrochemic~l cells, and anode, as well as cathode co~palL~I~ents permit thermal expansion and contraction of individual tubular cells within large cell bundles and reduces stress within the cell apparatus. However, in a leaking arrangement, it is expected that some loss of H2 gas will occur. To reduce H2 gas loss, make-up steam can be injected into the col.,~a l"lent between the barrier boards 22 and 24 so that H2 transfer is minimi7ed, thereby impeding the loss of H, during the energy storage mode. Consequently, a part of the make-up steam is vented with the generated ~2 during electrolysis and any H2 lost by flow through barriers CA 022ll39l l997-07-24 W 096123322 PCTrUS~6/00618 _ 9 _ and 24 is reoxidized with oxygen in a combustion ~one 26 and ~Yh~-ctPd to the atmosphere. Any exh~lct flow from the combustion chamber during energy storage operations is an energy loss flow and should be mintmi7ed. Blowers 28 positioned in a low te,--pelature region effect the c~thode recircul~tion.
Referring now to Figure 2, an electroçh~rnic~l fuel cell apparatus 2 operated inan energy recovery mode is shown, containing at least one axially elongated, tubular electrochemic~l fuel cell 30, such as a high tel,lpelature, solid oxide electrolyte fuel cell. In the energy recovery mode, the stored chemical energy in the form of Fe is converted into direct current (DC) electrical energy, and llltim~tçly to alternating current (AC) electrical energy.
The electrochemical fuel cell apparatus 2 is shown cont~inin~ at least one axially elongated, tubular electrochernit~l fuel cell 30, such as high telllpt;,dture, solid oxide electrolyte fuel cell. It should be recognized that a plurality of fuel cells 30 can be il~telconnP,cted in series and/or parallel arrangement as is well known in the art and used. It should also be recognized that the Ç ,~,~goi,~g description of the prefe~led tubular configuration is merely exemplary and should not be considered limiting in any manner. It is possible that other configurations for the fuel cell could be used, for example, flat plate configurations. Each tubular fuel cell 30 has an exterior porous electrode or fuel anode 32, an interior porous electrode or oxidant cathode 36, and a gas-tight solid oxide electrolyte 34 between the electrodes, as is well known in the art.
It should further be recognized that the location of the anode and cathode can be inverted.
Moreover, in the energy storage and conversion system of the invention, it should be recognized that the electroçh~mi~l electrolysis cell dlJp~dtllS 1 and the electrochemic~l fuel cell apparatus 2 can be one and the same, being capable of operating in two reversible modes, an electrolysis or energy storage mode and a fuel cell or energy recovery mode.
The fuel cell 30 is also intended to operate at elevated t~.--peldtules in the te.npeldture range of about 600~C to 1200~C. The fuel cell reaction is exothermic.
The pfefefl~ed configuration is based upon a fuel cell system in an energy recovery mode, wherein an incoming H2O (steam) passes through the at least one Fe/FeO storage W 096/23322 PCTrUS96/00~8 reactor bed 40 in the Fe state. It should be recognized that a plurality of storage reactor beds can be used. It should further be recognized that the a~ least one storage reactor beds 20 and 40 can be one and the same, being capable of operating in two reversible modes, a reduction or energy storage mode and an oxidation or energy S recovery mode. In the Fe/FeO storage reactor bed 40, the energy recovery reaction is the reverse of Equation (S) in that the H20 (steam) reacts with the Fe at l~",~e, dtures of about 600~C to 800~C, to produce FeO and H2 gas. The energy discharge reaction is .~resented by Equation (6).
Fe + H2O = FeO + H2 (6) An oxidant, such as air or ~2,is directP~ from an external source through a gas feed tube through the inside of the fuel cell 30 over the interior oxidant cathode 36 and the H2 gas produced is circulated and directed over the exterior fuel anode 32 of the electrochemical fuel cell 30 where the H2 gas is electrochemi~lly oxidized at the anode 15 32/solid oxide electrolyte 34 interface, by migrating oxygen ions produced at the solid oxide electrolyte 34/cathode 36 interface, to produce H2O (steam) and release electrons which are carried away through an external load circuit 38 to the cathode, thereby generating a flow of direct current electrical energy, and also thermal energy which can be recovered. The DC electrical energy can be ~lltim~t~ly converted by conventional 20 methods to AC electrical energy for electrical power tr~ncmi~ )n.
The electrochernir~l reactions in the electrochPrnic~l fuel cell are according to Equations (7), (8) and (9).
cathode: ~2 + 4e~ = 2O2- (7) anode: 2H2 + 2O2- = 2H2O + 4e~ (8) over~l: 2H2 + ~2 = 2H2~ (9) The H20 (steam) produced during electroçhPmi~l fuel cell operation at the exterior fuel anode 32 is recirculated over the Fe/FeO storage reactor bed 40 again and t again until subst~nti~lly all of the Fe is oxidized and converted back to FeO and H2 produced is fed as the fuel gas to the fuel cell for electrical power generation.
CA 022ll39l l997-07-24 W 096/23322 PCT~US96/00618 During the fuel cell mode of operation, excess heat should be .li~cip~tPd, the.cfo~c;, an excess of oxidant, air or ~27 should be used to cool the fuel cell.
Furthermore, due to the incomplete sealing of two porous flow barriers 42 and 44between the anode 32 and cathode 36 eo~ LIllents of the fuel cell 30, some loss of Swater vapor from the recirc~ titl~ gas and some hydrogen loss will result, both of which will leak into a combustion zone 46, and be combusted and e~th~ustçd with the excess oxidant as elch~llct gas. Make-up steam can be injected into the colllp~LIllent between barriers 42 and 44 in order to compen~te for the H2O and H2 losses during the energy recovery mode. The thermal energy of the oxidant exhaust can be recovered 10to generate make-up steam, stored as sensible heat, used for covering system heat losses, or used for other purposes. Blowers 48 positioned in a low temperature region effect the anode recirculation.
The inner electrode, or the electrolysis anode 16 during the energy storage modeand the oxidant cathode 36 during the energy recovery mode, of the electrochemical 15cell apparatus 1 and 2 can be comprised of a porous, doped ceramic of the perovskite family, that is, doped lanthanum chromite, lanthanum m~ng~nitP, or the like. The solid oxide electrolyte 14 and 34 can be comprised of a subct~nti~lly gas-tight oxygen ion conductive material, that is, yttria or scandia stabilized zirconia. The outer electrode, or the electrolysis e~thc)de 12 during the energy storage mode and the fuel anode 32 20during the energy recovery mode, can be comprised of a porous nickel-zirconia cermet material. A porous calcia stabilized zirconia support for the inner electrode can optionally be used. A subst~nti~lly gas-tight inle~connection (not shown) for electrically connecting adjacent electrochtomi~l cells made of doped l~nth~nllm chromite can also optionally be used.
25Referring now to Figure 3, an electrochemical energy conversion and storage cell (ECAS) apparatus 50 is shown, such as a high telllpeldture, solid oxide electrolyte fuel cell generator apparatus. The apparatus 50 can be operated in two modes, anenergy storage mode and an energy recovery mode. The ECAS apparatus 50 shown 9 contains two electrochemical cell bundles 52 and 54, each cell bundle containing a 30plurality of parallel, axially elongated, tubular electroehemic~l cells 56. Each cell has a porous exterior electrode 58 (that is, an electrolysis cathode or fuel anode), a porous CA 022ll39l l997-07-24 W 096/23322 PCTrUS96/00648 interior electrode 62 (that is, an electrolysis anode or air cathode), and a gas-tight solid oxide electrolyte 60 between the electrodes. The solid oxide electrolyte is a solid solution of oxides st~lected for its high ratio of ionic conductivity to electronic conductivity, high oxygen ion to cation conductivity, and gas-tightness as a barrier to 5 the gases in the anode and cathode COlllp~ ~",ents so that direct reaction does not occur.
As is well known, the construction of the electrochemical cells 56 can include:
~n optional inner porous support tube (not shown) of calcia stabilized zirconia about 1.0-2.0 mm thick; an inner porous electrolysis anode or air cathode 62 generallysurrounding the support tube of doped perovskite oxides, for example LaMnO3, CaMnO3, LaNiO3, LaCoO3, LaCrO3 or the like including dopants of Sr, Ca, Co, Ni, Fe, Sn, Ba, Cr, Ce or the like, about 0.05mm-5.0mm thick; a gas-tight solid oxide electrolyte 60 of yttria or scandia stabilized zirconia about 0.001mm-0.1mm thic~
surrounding most of the outer periphery of the inner electrode; a gas-tight interconnection material (not shown) of doped LaCrO3 including dopants of Ca, Sr, Ba, Mn, Mg, Ti, Fe, Co and Ni about 0.001-0.Smm thick on a sçlç~tçd radial portion of the inner electrode in a discontinuous portion of the solid oxide electrolyte for electrical intcrconnection between adjacent cells; an outer electrolysis cathode or fuel anode 58 of nickel-zirconia or cobalt-zirconiacermetaboutO. lmm thick subst~nti~lly surrounding the solid oxide electrolyte and discontinuous in the interconnection region to avoid direct electrical communication between the outer electrode and both the interconnection and inner electrode; an optional top layer (not shown) of nickel-zirconia or cobalt-zirconia cermet about 0.1mm thick is over the interconnection; and an optional electrically conductive nickel fiber felt about lmm thick over the intelconnection, thereby forming an electrochemical cell.
An outer metallic housing 64 of steel generally surrounds the entire ECAS
apparatus 50. An inner housing 65 of high temperature resistant metal such as Inconel generally surrounds a plurality of chambers, including a cell chamber 70, a combustion/ç~h~st chamber 80, and a FelFeO energy storage bed reactor chamber 88.
Thermal insulation 66 such as low density ~lnmin~, is contained within the outerhousing. Penetrating the outer housing and thermal insulation is a tubular gaseous W O 96123322 PCT~US96/OOCq8 oxidant inlet 68 for an oxidant such as air or O2~dnd a gaseous steam inlet 78. Ports can also be provided for electrical leads (not shown).
The cell chamber 70 containing the cell bundles 52 and 54 extends between a gas distribution plate 72 and porous barriers 74 and 76, such as ceramic fiber boards 5 or the like. The electroch~mi~l cells 56 extl-n~ling between distribution plate 72 and porous barriers 74 and 76 and have open ends 86 in the combustion/exhaust chamber 80, and closed ends in the cell chamber 70 at the bottom of the cells near the distribution plate 72. Penetrating the colllpal ~Illent between the porous barriers 74 and 76 is a make-up steam inlet 78, used to inject make-up steam so that transfer of H
10 produced during electrolysis operations in the energy storage mode and H2O produced during fuel cell operations in the energy recovery mode is not subst~nti~lly lost through the porous barrier to a combustion/exhaust chamber 80 and e~h~l~cted in an exhaust channel 82 as hot combusted exh~l~ct gas.
Beneath the porous barriers is a hydrogen gas (electrolysis mode) or steam (fuel15 cell mode) recirculation ch~nnPl 84. The recirculation cll~nn~l 84 connects to at least one Fe/FeO energy storage bed reactor chamber 88, cont~ining a packed bed of iron oxide/iron metal compacts or pellets 90. The Fe/FeO energy storage bed chamber 88 can be tubular, annular, planar or the like. The energy storage bed can be sized in wide margins and is governed by ECAS ~dtUS size and other operational 20 considerations. For example, a smaller bed can be thermally integrated into the a~dLus more easily but it would have less energy storage capacity. The Fe/FeO
pellets can be configured in various shapes, such as irregular lumps, spherical, oblate spheroid, annular ("Raschig rings"), wagon wheel or the like. The ~e/FeO pellets can also be comprised of il,lpl~gn~t~cl iron oxide/iron metal in high lGIlll-Glatule ceramic 25 substrates, such as ~lllmin~ ~Ul~lJOll material, or better as pure solid Fe/FeO. An active bed volume of 108-240 m3 for a 25MV electrochemical apparatus is plGfGllGd. The ~ actual volume of the Fe/FeO pellets is about 32 m3. The pellet size, shape, strength, uSity, and packing density are important parameters for effective operation in terms of size, structural, thermal and pressure drop characteristics and can be determined by 30 operational analysis. The Fe/FeO energy storage chamber 88 is coupled to recirculation CA 022ll39l l997-07-24 W 096/23322 PCTrUS96/00648 blowers 92 positioned at a low te~ )erdture region for recirculation of the gases in the recirculation ch~nn~l 84 to a gaseous feed inlet to the electrochemi-~l cells 56.
By way of example, during operation of the ECAS apparatus 50 in the electrolysis or energy storage mode, excess AC electrical energy produced from a5 power plant during off-peak hours, is converted to DC by conventional methods well known in the art and fed through the electrical leads 94 to the electrochemical cells 56 dted at a telllpe~dture above 350~C and about 600~C to 1000~C. Fresh (preheated)water vapor (steam) is fed through an inlet 78 and passes over the axial portion of the outer electrolysis cathode 58 and is electrochernic~lly reduced to H2 gas and oxygen 10 ions. The hydrogen gas produced is directed to pass from the cell chamber 70 into the recirculation ch~nnel 84. Meanwhile, the oxygen ions pass through the solid oxide electrolyte 60 and are electrochemically oxidized at the inner anode 62 to produce ~2 which is vented as a by-product at the open ends of the cells into the combustion/exh~ t chamber 80 and is eYh~ t~ to the atmosphere or recovered, if 15 possible. Make-up steam is injected through an inlet 78 into the col"l)a"",ent between porous barriers 74 and 76 to prevent H2 gas loss by reoxidation in the combustion chamber with eYh~ ted oxygen.
The H2 gas in the recirculation ch~nn~l 84 iS passed through a Fe/FeO energy storage bed 88 cont~ining FeO and reacts at ~e,.,pe~atures of about 600~C to 800~C to 20 form Fe and H2O (steam). The H2O steam is recirculated by blowers 92 in the recirculation ch~nnel 84 to the cell ch~mber 70. The steam is recirculated and electrolyzed over and over again until subst~nti~lly complete reduction of FeO to Fe and accordingly until substantially complete charging of the Fe occurs. When all the beds 88 of FeO are reduced to Fe (only one bed being shown in Fig. 3), the energy storage 25 capability is eYh~ ted Only a small amount of injected fresh steam is needed to reduce a large amount of FeO to Fe due to the recirculation of steam to the outer cathode of the electrolysis cell. Thus, in the energy storage mode, excess electrical energy produced from the power plant is stored as chemi~l energy, not in the form of bulky H2 gas, but in the form of iron (Fe) metal pellets which provide a compact and 30 recoverable energy storage arrangement.
W 096/23322 PCTrUS96/00648 When the electrical energy is needed for electrical power tr~nsmicsion from the power plant, the ECAS apparatus 50 is operated in an energy recovery mode. During operation in the fuel cell or energy recovery mode, stored chemic~l energy in the form of iron metal is converted via the oxidation of hydrogen, released from the energy 5 storage bed through oxidation of iron (Fe) through incoming steam, in the fuel cell to DC electrical energy and then converted to AC electrical energy by conventional methods for electrical power tr~n~mi~cion. Fresh (preh~t~) water vapor (steam) is fed through inlet 78 and drawn into the recirculation channel 84 by the recirculation blower 92 and then is fed over the Fe/FeO energy storage bed 88 in the previous Fe 10state at temperatures of about 600~C to 800~C to oxidize the Fe to FeO and produce H2 gas. The H2 gas produced is passed over the exterior fuel anode 58 of the electrochenlic~l cell where it electrochemically reacts along the outer axial length with oxygen ions to produce direct current electrical, heat and H2O, which is, again,circulated through channel 84 to bed 88.
15An oxidant, such as air or ~2~ typically supplied in excess for cooling and/orheat transfer, is fed through inlet 68 and is partially prehlo~tt~d while it flows through the oxidant manifold and conduits which extend down the inside length of the electrochP-mir~l cells 56 at te~ )eldtures of about 1000~C. The oxidant is discharged into the closed end (bottom) of the electrochemir~l cells and then reverses direction and 20 electrochtomic~lly reacts at the inner air ç~thode 62 along the inside of the active length of the electrochemical cells, being depleted in oxygen as it approaches the open ends 86 of the cells. The depleted or spent oxidant is discharged into the combustion/exhaust chamber 80 through the open cell ends, where it combusts with some depleted or spent hydrogen which passes through porous barriers 74 and 76 to form a hot combusted 25 exhaust gas which can be directed to pass in an exhaust channel 82 in heat comm--nic~tion with other parts of the electrochemic~l apparatus, prior to exiting into the atmosphere. Oxygen ions formed by this electrochemical reaction become a part of the solid oxide electrolyte crystal structure and migrate through the solid oxide electrolyte to the exterior fuel anode 58, where the H2 gas supplied from the FelFeO
30 energy storage reactor 88 is directed over the axially length of the fuel anode is electrochemically oxidized and electrons are released which flow through an external W O 96/23322 PCTrUS96/00648 load circuit to the air cathode, thus generating direct current electrical energy. T h e H2O (steam) produced at the fuel anode 58 during electroçhemiç~l reactions is recirculated over and over again in recirculation ch~nnel 84 to the Fe/FeO beds 88 until subst~nti~lly complete oxidation of Fe to FeO occurs, and accordingly until substantially S complete discharging of Fe occurs. Only a small amount of injected fresh steam is needed to oxidize a large amount of Fe to FeO due to the recirculation of produced steam. Since the energy recovery mode is exothermic, an excess of air is needed to cool the cells. Further, due to incomplete sealing of the porous barrier, some loss of water vapor from the recirculation gas stream and of depleted hydrogen will occur and combust with the excess air in the combustion chamber. Make-up steam is injectedthrough inlet 78 into the co-"pal l---ent between porous barriers 74 and 76 to minimize H2O and H2 loss.
Referring now to Figure 4, this figure shows the energy conversion and storage cell voltage characteristics on charge (electrolysis mode) and on discharge (fuel cell 1~ mode). The energy efficierlcy of a charge/discharge cycle depends on the current density during charge and discha ~,e. The surface area under each operating point is the power equivalent (watts). The energy equivalent is obtained by multiplying a time factor (hours). The ratio of watt x hours (input)/watt x hours (output) represents the cell energy efficiency which must also take into consideration additional losses such as gas (steam) losses, heat losses and ~ ry electrical losses from blowers, controls, etc. The system of the invention can be used as an alternative for conventional energy storage applications. The system has the additional ability to act as a natural gas operated fuel cell power plant which offers the advantage of electrochemical energy storage.
The invention having been disclosed in connection with the foregoing variations and examples, additional variations and examples will now be apparent to personsskilled in the art. The invention is not intended to be limited to the variations and examples spe~ific~lly mentioned, and accordingly reference should be made to theappended claims rather than the foregoing discussion of plefel,~d examples to assess the spirit and scope of the invention in which exclusive rights are claimed.
The invention relates to the field of energy conversion and storage in electrical power plant operations during off-peak power plant operations. More particularly the invention relates to elecll~rllf....i~l cells, such as a high ~ dture, solid oxide dectrolyte fuel cells ~.,.dted in an electrolysis mode, used for converting electrical energy to ch~o~nir~l energy in the form of hydrogen gas, which converts iron oxide to met~l, thereby forming compactly stored chemical energy, and the stored chrnlir~l energy can later be reconverted via hydrogen into electrical energy in electroçhPmic ~l fuel, such as high le"~pe~dture, solid oxide electrolyte fuel cells operated in a fuel cell mode.
Even more particularly, the invention is directed to an apparatus for and a method of converting and storing of electrical energy in the form of chPmic~l potential energy during off-peak electrical power plant operations by the following operations:
electrolyzing H20 (steam) to H2 and ~2 in an electroc hetnic~l electrolysis cell operating on electrical energy supplied from an external source; passing the H2 produced through 15 a storage reactor bed of iron oxide (FeO) that is thermally coupled to a heat source, wherein the iron oxide (FeO) is reduced to iron metal (~;e) to form stored chemir~l potential energy for extended periods; later, when elrctric~l energy is called for, passing H2O (steam) through the storage reactor bed, wherein the iron metal (Fe) is oXi~li7f'd to FeO and chemical potential energy is recovered as H2; and then oxidizing 20 the H2 recovered in an electrochemir~l fuel cell to generate electrical energy for tr~ncmi.c.cion .
W O 96/23322 PCTrUS~G/OCC~18 Base load power plants such as nuclear power plants and combustion-thermal power plants are preferably operated under a constant load. Peak power electrical energy requirements are basically undesirable from a standpoint of highly efficient generation of electrical energy, but must be met on a daily and seasonal routine. Peak S power electrical energy demand per-~li7es power generation f~cilities basically in the form of increased capital cost and generally higher fuel cost. To make additional electrical power capacity available during peak demand periods, higher than required capacity usually exists during off-peak periods which therefore requires energy storage systems.
The periods of low power demand, thus, leave the base load power plant operating under less than optimal conditions and excess power generation capacity is available during such periods. It is very desirable in this in~t~nce to store electrical energy efficiently and at low costs, and many schemes have been proposed for such energy storage f~rilitirs For example, "pumped hydro" and "co~ r~s~d air" energystorage systems have been used. These systems store energy in the form of potential energy during off-peak hours and return the energy to the power group during peak power ~lem~ncl periods. Such practical sch~mrs are depçn-lent on geography and geology and require ci~nific~nt space, and, therefore, the siting of such energy storage f~r.ilitirs is not flexible enough for wide-spread applications.
Electrochemir~l energy storage systems however would have distinct advantages over other systems. Electroch~omir~l energy storage systems are highly compact because chemic~l energy can be stored in a small volume. For this reason, it can be modular in construction. It also has a potential for being the most energy efficient method for storage of electrical energy since the energy conversion of electrical to merh~nir~l and back to electrical energy is avoided.
High temperature, solid oxide electrolyte fuel cells and multi-cell generators and configurations thereof designed for converting chemic~l energy into direct current electrical energy at temperatures typically in the range of 600~C to 1200~C are well known and taught, for example, in U.S. Patent Specification Nos. 4,395,468 (Isenberg) and 4,490,444 (Isenberg). These high le.,l~ef~ture, solid oxide electrolyte fuel cells are known to operate in two modes, namely in an electrochemical power generation mode using gaseous fuel such as hydrogen or carbon monoxide derived from reformed hydrocarbons, coal, or the like, which is converted to direct current electrical energy, and in an electrochemical power usage mode using steam and carbon dioxide which is converted via electrolysis into oxidizable fuels such as hydrogen or carbon monoxide, S lespeclively. This capability of the high te".~elaL.lre, solid oxide electrolyte fuel cells is unique among fuel cell types and is due to the fact that the solid oxide electrolyte fuel cells are solid state devices which operate in a te"-l,eldL.lre range of about 600~C to 1200~C. At these temperature levels, the thermal energy is high enough that electrolysis can proceed without using noble metal catalysts at the electrodes, and the 10 laws of thermodynamics predict, and are confirmed by experiment, a reduced electrical power requirement for electrolysis as compared to low ~ ,dture electrochemit~l batteries. For example, sodium-sulfur batteries that operate at about 350~C have been investi~t.od for use in storing off-peak electrical energy.
Producing fuels, such as hydrogen fuel gas, by electrolysis is a basic 15 re~uirement for an electrochemical energy conversion and storage system. The energy storage in the form of hydrogen fuel gas through the electrolysis of steam, however, would re~uire bulky gas storage f~rilitilos and would restrict the siting of this type of energy conversion and storage system. Therefore, there is a need to convert the bulky hydrogen energy carrier into another form of energy carrier which is not bulky and can 20 be stored in a compact arrangement. At the a~ "iale demand time, this potential energy can be called into service by reconversion to hydrogen as a fuel to a fuel cell generator to generate electrical energy.
What is needed is an efficient and compact method of storing electrical energy in the form of cherni~l energy that is relatively compact and can be stored indefinitely 25 for later reconversion to electrical energy for electrical power tr~nsmicsion.
It would be advantageous and it is an object of the invention to derive an energy storage and conversion system from high L~ e-dture, solid oxide electrolyte fuel cells operating in two modes, that is 1. an electrolysis mode for electrical energy storage and 2. a fuel cell mode for electrical energy recovery, using iron metal and iron oxide 30 (Fe/FeO) beds as the energy storage mediums.
W 096/23322 PCTrUS96/00648 It is another object of the invention to provide an energy conversion and storage system by storing electrical energy as chemical energy by the electrolysis of H2O
(steam) in a high temperature, solid oxide electrolyte electrolysis cell for H2 production and subsequent storage of this chemical energy in the form of Fe metal, by reduction 5 of FeO with H2 in a storage reactor bed, and later by converting the stored chemical energy to electrical energy by the reaction of H2O (steam) with the Fe in the storage reactor bed for H2 gas production and subsequent use of the H2 gas produced in the high ~e~ dture, solid oxide electrolyte fuel cell generator as fuel to generate and recover electrical energy.
These and other objects of the invention are accomplished by a method of storing electrical energy as chemical energy and recovering the electrical energy from the stored che~ l energy by operating an electrochPmi/~.~l cell in two modes, anenergy storage mode and an energy recovery mode, characterized by the steps in an energy storage mode of: (A) supplying external electrical energy to electrical leads and H20 (steam) gas to a c~thode of at least one electrocht~mic~l cell operating as an electrolysis cell using a solid oxide electrolyte between an anode and the cathode, the electrolysis cell ope.ating at a lt;lllpe,dture of between 600~C and 1000~C, to produce H2 gas along the cathode and ~2 gas along the anode; (B) passing the ~2 gas produced along the cathode of the electrolysis cell into a energy storage reactor containing iron oxide operating at a temperature of between 600~C to 800~C, and produce iron metal in the energy storage reactor and H2O (steam); (C) recirculating the H2O (steam)produced in the energy storage reactor to the cathode of the electrolysis cell to be electrolyzed; and, (D) repe~;ng steps (A) to (C) until subst~nti~lly complete conversion of iron oxide to iron metal, for chemic~l energy storage of electrical energy; and, further characterized by the steps in an energy recovery mode of: (E) supplying H20 (steam) gas to the energy storage reactor co~ ining iron metal operating at a temperature of between 600~C and 800~C, to produce iron oxide in the energy storage reactor and H2 gas; (F) passing the H2 gas to a fuel anode of the at least one electrochemic~l cell operating as a fuel cell and supplying ~2 gas or air to an air cathode of the at least one electrochemical cell operating at a temperature of between 600~C and 1200~C, to conduct electrical energy along the external leads and produce CA 022ll39l l997-07-24 W O 96/23322 PCTrUS9GJC~'18 H2O (steam) along the fuel anode; (G) recirculating the H2O (steam) produced at the fuel anode of the fuel cell to the energy storage bed; (H) repeating steps (E) to (G) until substantially complete conversion of iron metal (Fe) to iron oxide and H2 gas for electrical energy recovery from chernir~l energy storage; and, (I) recovering the 5 electrical energy produced.
The invention also resides in an electrochemical energy conversion and storage device operational in two modes, an energy recovery mode and an energy storage mode that is characterized by: (A) an electrochemical cell chamber, the cell chamber con~ining at least one electrochemical cell bundle, the cell bundle containing a plurality 10 of parallel, axially elongated, interconnected electrochemi~l cells, each cell including a porous exterior electrode, a porous interior electrode, and a gas-tight solid oxide electrolyte between the two electrodes; (B) a combustion çh~mber connected to the cell ch~mher; (C) at least one combustion eYh~l~st ch~nn~l connPct~ from the combustion chamber to the atmosphere; (D) at least one energy storage chamber connected to the 15 cell chamber, the energy storage chamber con~illitlg either iron oxide in the energy storage mode of operation or iron metal in the energy recovery mode of operation; (E) at least one recirculation gas çh~nnel connPct~ from outside of the porous exterior electrode in the cell cll~mb~-r to the energy storage chamber; (F) a steam inlet connected to the outside of the porous exterior electrode in the cell chamber; (G) an oxidant inlet 20 connected to the inside of the porous interior electrode in the cell chamber; and, (H) electrical leads connected from the cell bundles in the cell chamber to an external circuit, in which the device can be o~eiated in an energy storage mode by supplying direct current electrical energy from the external circuit through the leads to the electroc~l~mic~l cells and steam through the steam inlet to the porous exterior electrode 25 and providing the energy storage chamber in the iron oxide state, and in which the device can be operated in an energy recovery mode by providing the energy storage chamber in the iron state and supplying steam through the steam inlet to the energy storage chamber and an oxidant through the oxygen inlet to the porous interior electrode ~ and recovering direct current electrical energy from the electrochemical cells through 30 the leads to the external circuit.
W 096/23322 PCT~US~C~'CAC~8 There exist several iron oxide compositions, such as FeO, Fe,03, Fe30,. For simplicity we name here only FeO, since it is in chernic~l equilibrium with iron (Fe).
However the formation of the other oxides of iron in the scheme of the invention is not excluded.
There are shown in the drawings certain exemplary embodiments of the invention as presently preferred. It should be understood that the invention is not limited to the embodim~nh fli~;close~l as examples, and is capable of variation within the scope of the appended claims. In the drawings:
FIGURE 1 is a schematic of the electrical energy storage and conversion system of the invention being operated in the energy storage mode, FIGURE 2 is a schematic of the electrical energy storage and conversion system of the invention being operated in the energy recovery mode, FIGURE 3, which best illustrates the invention, is a sectional view of an exempl~ry electrical energy storage and conversion system of the invention which can be operated in an energy storage mode and an energy recovery mode, and FIGURE 4 is a graph of the cell voltage characteristics on charge and discharge of the electrical energy storage and conversion system of the invention.
The term "electrolysis cathode" and "fuel anode" as used herein means that electrode in contact with a hydrogen species such as H2O (steam), H2 gas, or hydroc.~bon fuel, such as natural gas. The term "electrolysis anode" and "oxidant c~tho~le" as used herein means that electrode in contact with an oxygen species, such as ~2 or air. The term "spent" as used herein means partially reacted or depleted according to the electrochemical equations described herein. The term "combustedexhaust gas" as used herein means a combusted mixture of hydrogen or fuel with oxidant or air. The term "iron oxide" as used herein includes several iron oxidecompositions, such as FeO, Fe,03, and Fe304. For simplicity, we name only FeO, since it is in chemical equilibrium with iron (Fe). However, the formation of other oxides of iron in the scheme of the invention is not excluded.
Referring now to Figure 1, an electrochelniç~l electrolysis cell apparatus 1 operated in an energy storage mode is shown, cont~ining at least one axially elongated, tubular electrochemical electrolysis cell l0, such as high telnpe,at~lle, solid oxide W O 96123322 PCT~US~6100CS8 electrolyte electrolysis cell. It should be recognized that a plurality of electrolysis cells 10 can be interconnectP~ in series and/or parallel arrangement as is well known in the art and used. It should also be recognized that the foregoing description of thepreferred tubular configuration is merely exelnpl~ry and should not be considered limitin~ in any manner. It is possible that other configurations for the electrolysis cell could be used, for example, flat plate configurations. Each tubular electrolysis cell 10 has an exterior porous electrode or electrolysis cathode 12, an interior porous electrode or electrolysis anode 16, and a gas-tight solid oxide electrolyte 14 between theelectrodes, as is well known in the art. It should further be recognized that the location of the anode and cathode can be inverted.
The electrolysis cell 10 is intenderl to operate at elevated le~ e~atures, over about 600~C to 1200~C, and typically in the l~"~peldture range of about 650~C to1200~C, preferably about 800~C to about 1000~C. The cell telllpel~ re is m~int~in~od by ohmic r~ t~ce losses or better by heat exçh~nge with other sources of heat energy.
The ~,eI~"ed configuration is based upon an electrolysis cell system, in energy storage mode wherein at te",~e~dtures of about 800~C to 1000~C, an incoming H2O (steam) is directed axially over the outside of the electrolysis cell 10 and a direct current of electrical energy produced from an electrical power plant (converted by conventional methods from AC to DC current prior to being supplied to the electrolysis cell) is directed through an external load circuit (not shown) by electrical leads 18 to the electrolysis c~tho~le 12. During operation, water (steam) molecules are fed to the electrolysis cathode 12 and pass through the porous cathode and electrochemi~lly react at the solid oxide electrolyte 14/cathode 12 interface, to produce hydrogen gas which exits the electrolysis cell 10 at the ç~thode. Oxygen ions pass through the solid electrolyte 14 and are then electrochemically oxidized at the solid oxide electrolyte 14/anode 16 interface, to produce oxygen gas which exits the electrolysis cell at the anode and is vented to the atmosphere as a by-product of energy storage or recovered, if possible.
~ The electrochernic~l reactions in the electrolysis cell are according to Equations (2), (3) and (4).
W 096/23322 PCT~US96/00648 cathodç:2H2O + 4e- = 2O2- + 2H2 (2) anode: 2O2- = 4e~ + ~2 (3) overall: 2H2O = 2H2 + ~2 (4) S The hydrogen gas (H2) produced during electrolysis of steam exits the electrolysis cell 10 and passes through at least one iron/iron oxide (Fe/FeO) storage reactor bed 20 collt~ini.~ compacts of iron oxide (FeO) operating at te~ )e-dtures of about 600~C to 800~C, to produce compacts of iron metal (Fe) and water (steam). It should be recognized that a plurality of connected storage reactor beds can be used.
The energy storage reaction is rep.ese.lted by Equation (5).
FeO + H2 = Fe + H2O (S) The water vapor produced recirculates and passes again and again to the cathode 12 of the electrolysis cell 10 until subsl~nt;~lly all of the FeO is reduced to Fe. Due to the c~thode gas recirculation, a very small amount of hydrogen/steam is required for the subst~nti~lly complete reduction of a large amount of FeO to Fe via the energy storage mode. When all the FeO in all the Fe/FeO beds 20 is reduced to Fe, the energy storage capability is e~th~tlcte~.
Since the anode 16 and cathode 12 co..,palL-nents of the electrolysis cell l0 are not absolutely hermetiç~lly sealed against each other, some H2 may be lost to the anode side 16 through two porous barrier boards 22 and 24 which results in an overall system energy loss. In this arrangement, the spent anode and cathode gases as well as anode and cathode co-~ nents are separated from each other through high temperature, porous ceramic fiber boards, such as porous ~lumin~ boards (not shown). The absence of rigid seals between electrochemic~l cells, and anode, as well as cathode co~palL~I~ents permit thermal expansion and contraction of individual tubular cells within large cell bundles and reduces stress within the cell apparatus. However, in a leaking arrangement, it is expected that some loss of H2 gas will occur. To reduce H2 gas loss, make-up steam can be injected into the col.,~a l"lent between the barrier boards 22 and 24 so that H2 transfer is minimi7ed, thereby impeding the loss of H, during the energy storage mode. Consequently, a part of the make-up steam is vented with the generated ~2 during electrolysis and any H2 lost by flow through barriers CA 022ll39l l997-07-24 W 096123322 PCTrUS~6/00618 _ 9 _ and 24 is reoxidized with oxygen in a combustion ~one 26 and ~Yh~-ctPd to the atmosphere. Any exh~lct flow from the combustion chamber during energy storage operations is an energy loss flow and should be mintmi7ed. Blowers 28 positioned in a low te,--pelature region effect the c~thode recircul~tion.
Referring now to Figure 2, an electroçh~rnic~l fuel cell apparatus 2 operated inan energy recovery mode is shown, containing at least one axially elongated, tubular electrochemic~l fuel cell 30, such as a high tel,lpelature, solid oxide electrolyte fuel cell. In the energy recovery mode, the stored chemical energy in the form of Fe is converted into direct current (DC) electrical energy, and llltim~tçly to alternating current (AC) electrical energy.
The electrochemical fuel cell apparatus 2 is shown cont~inin~ at least one axially elongated, tubular electrochernit~l fuel cell 30, such as high telllpt;,dture, solid oxide electrolyte fuel cell. It should be recognized that a plurality of fuel cells 30 can be il~telconnP,cted in series and/or parallel arrangement as is well known in the art and used. It should also be recognized that the Ç ,~,~goi,~g description of the prefe~led tubular configuration is merely exemplary and should not be considered limiting in any manner. It is possible that other configurations for the fuel cell could be used, for example, flat plate configurations. Each tubular fuel cell 30 has an exterior porous electrode or fuel anode 32, an interior porous electrode or oxidant cathode 36, and a gas-tight solid oxide electrolyte 34 between the electrodes, as is well known in the art.
It should further be recognized that the location of the anode and cathode can be inverted.
Moreover, in the energy storage and conversion system of the invention, it should be recognized that the electroçh~mi~l electrolysis cell dlJp~dtllS 1 and the electrochemic~l fuel cell apparatus 2 can be one and the same, being capable of operating in two reversible modes, an electrolysis or energy storage mode and a fuel cell or energy recovery mode.
The fuel cell 30 is also intended to operate at elevated t~.--peldtules in the te.npeldture range of about 600~C to 1200~C. The fuel cell reaction is exothermic.
The pfefefl~ed configuration is based upon a fuel cell system in an energy recovery mode, wherein an incoming H2O (steam) passes through the at least one Fe/FeO storage W 096/23322 PCTrUS96/00~8 reactor bed 40 in the Fe state. It should be recognized that a plurality of storage reactor beds can be used. It should further be recognized that the a~ least one storage reactor beds 20 and 40 can be one and the same, being capable of operating in two reversible modes, a reduction or energy storage mode and an oxidation or energy S recovery mode. In the Fe/FeO storage reactor bed 40, the energy recovery reaction is the reverse of Equation (S) in that the H20 (steam) reacts with the Fe at l~",~e, dtures of about 600~C to 800~C, to produce FeO and H2 gas. The energy discharge reaction is .~resented by Equation (6).
Fe + H2O = FeO + H2 (6) An oxidant, such as air or ~2,is directP~ from an external source through a gas feed tube through the inside of the fuel cell 30 over the interior oxidant cathode 36 and the H2 gas produced is circulated and directed over the exterior fuel anode 32 of the electrochemical fuel cell 30 where the H2 gas is electrochemi~lly oxidized at the anode 15 32/solid oxide electrolyte 34 interface, by migrating oxygen ions produced at the solid oxide electrolyte 34/cathode 36 interface, to produce H2O (steam) and release electrons which are carried away through an external load circuit 38 to the cathode, thereby generating a flow of direct current electrical energy, and also thermal energy which can be recovered. The DC electrical energy can be ~lltim~t~ly converted by conventional 20 methods to AC electrical energy for electrical power tr~ncmi~ )n.
The electrochernir~l reactions in the electrochPrnic~l fuel cell are according to Equations (7), (8) and (9).
cathode: ~2 + 4e~ = 2O2- (7) anode: 2H2 + 2O2- = 2H2O + 4e~ (8) over~l: 2H2 + ~2 = 2H2~ (9) The H20 (steam) produced during electroçhPmi~l fuel cell operation at the exterior fuel anode 32 is recirculated over the Fe/FeO storage reactor bed 40 again and t again until subst~nti~lly all of the Fe is oxidized and converted back to FeO and H2 produced is fed as the fuel gas to the fuel cell for electrical power generation.
CA 022ll39l l997-07-24 W 096/23322 PCT~US96/00618 During the fuel cell mode of operation, excess heat should be .li~cip~tPd, the.cfo~c;, an excess of oxidant, air or ~27 should be used to cool the fuel cell.
Furthermore, due to the incomplete sealing of two porous flow barriers 42 and 44between the anode 32 and cathode 36 eo~ LIllents of the fuel cell 30, some loss of Swater vapor from the recirc~ titl~ gas and some hydrogen loss will result, both of which will leak into a combustion zone 46, and be combusted and e~th~ustçd with the excess oxidant as elch~llct gas. Make-up steam can be injected into the colllp~LIllent between barriers 42 and 44 in order to compen~te for the H2O and H2 losses during the energy recovery mode. The thermal energy of the oxidant exhaust can be recovered 10to generate make-up steam, stored as sensible heat, used for covering system heat losses, or used for other purposes. Blowers 48 positioned in a low temperature region effect the anode recirculation.
The inner electrode, or the electrolysis anode 16 during the energy storage modeand the oxidant cathode 36 during the energy recovery mode, of the electrochemical 15cell apparatus 1 and 2 can be comprised of a porous, doped ceramic of the perovskite family, that is, doped lanthanum chromite, lanthanum m~ng~nitP, or the like. The solid oxide electrolyte 14 and 34 can be comprised of a subct~nti~lly gas-tight oxygen ion conductive material, that is, yttria or scandia stabilized zirconia. The outer electrode, or the electrolysis e~thc)de 12 during the energy storage mode and the fuel anode 32 20during the energy recovery mode, can be comprised of a porous nickel-zirconia cermet material. A porous calcia stabilized zirconia support for the inner electrode can optionally be used. A subst~nti~lly gas-tight inle~connection (not shown) for electrically connecting adjacent electrochtomi~l cells made of doped l~nth~nllm chromite can also optionally be used.
25Referring now to Figure 3, an electrochemical energy conversion and storage cell (ECAS) apparatus 50 is shown, such as a high telllpeldture, solid oxide electrolyte fuel cell generator apparatus. The apparatus 50 can be operated in two modes, anenergy storage mode and an energy recovery mode. The ECAS apparatus 50 shown 9 contains two electrochemical cell bundles 52 and 54, each cell bundle containing a 30plurality of parallel, axially elongated, tubular electroehemic~l cells 56. Each cell has a porous exterior electrode 58 (that is, an electrolysis cathode or fuel anode), a porous CA 022ll39l l997-07-24 W 096/23322 PCTrUS96/00648 interior electrode 62 (that is, an electrolysis anode or air cathode), and a gas-tight solid oxide electrolyte 60 between the electrodes. The solid oxide electrolyte is a solid solution of oxides st~lected for its high ratio of ionic conductivity to electronic conductivity, high oxygen ion to cation conductivity, and gas-tightness as a barrier to 5 the gases in the anode and cathode COlllp~ ~",ents so that direct reaction does not occur.
As is well known, the construction of the electrochemical cells 56 can include:
~n optional inner porous support tube (not shown) of calcia stabilized zirconia about 1.0-2.0 mm thick; an inner porous electrolysis anode or air cathode 62 generallysurrounding the support tube of doped perovskite oxides, for example LaMnO3, CaMnO3, LaNiO3, LaCoO3, LaCrO3 or the like including dopants of Sr, Ca, Co, Ni, Fe, Sn, Ba, Cr, Ce or the like, about 0.05mm-5.0mm thick; a gas-tight solid oxide electrolyte 60 of yttria or scandia stabilized zirconia about 0.001mm-0.1mm thic~
surrounding most of the outer periphery of the inner electrode; a gas-tight interconnection material (not shown) of doped LaCrO3 including dopants of Ca, Sr, Ba, Mn, Mg, Ti, Fe, Co and Ni about 0.001-0.Smm thick on a sçlç~tçd radial portion of the inner electrode in a discontinuous portion of the solid oxide electrolyte for electrical intcrconnection between adjacent cells; an outer electrolysis cathode or fuel anode 58 of nickel-zirconia or cobalt-zirconiacermetaboutO. lmm thick subst~nti~lly surrounding the solid oxide electrolyte and discontinuous in the interconnection region to avoid direct electrical communication between the outer electrode and both the interconnection and inner electrode; an optional top layer (not shown) of nickel-zirconia or cobalt-zirconia cermet about 0.1mm thick is over the interconnection; and an optional electrically conductive nickel fiber felt about lmm thick over the intelconnection, thereby forming an electrochemical cell.
An outer metallic housing 64 of steel generally surrounds the entire ECAS
apparatus 50. An inner housing 65 of high temperature resistant metal such as Inconel generally surrounds a plurality of chambers, including a cell chamber 70, a combustion/ç~h~st chamber 80, and a FelFeO energy storage bed reactor chamber 88.
Thermal insulation 66 such as low density ~lnmin~, is contained within the outerhousing. Penetrating the outer housing and thermal insulation is a tubular gaseous W O 96123322 PCT~US96/OOCq8 oxidant inlet 68 for an oxidant such as air or O2~dnd a gaseous steam inlet 78. Ports can also be provided for electrical leads (not shown).
The cell chamber 70 containing the cell bundles 52 and 54 extends between a gas distribution plate 72 and porous barriers 74 and 76, such as ceramic fiber boards 5 or the like. The electroch~mi~l cells 56 extl-n~ling between distribution plate 72 and porous barriers 74 and 76 and have open ends 86 in the combustion/exhaust chamber 80, and closed ends in the cell chamber 70 at the bottom of the cells near the distribution plate 72. Penetrating the colllpal ~Illent between the porous barriers 74 and 76 is a make-up steam inlet 78, used to inject make-up steam so that transfer of H
10 produced during electrolysis operations in the energy storage mode and H2O produced during fuel cell operations in the energy recovery mode is not subst~nti~lly lost through the porous barrier to a combustion/exhaust chamber 80 and e~h~l~cted in an exhaust channel 82 as hot combusted exh~l~ct gas.
Beneath the porous barriers is a hydrogen gas (electrolysis mode) or steam (fuel15 cell mode) recirculation ch~nnPl 84. The recirculation cll~nn~l 84 connects to at least one Fe/FeO energy storage bed reactor chamber 88, cont~ining a packed bed of iron oxide/iron metal compacts or pellets 90. The Fe/FeO energy storage bed chamber 88 can be tubular, annular, planar or the like. The energy storage bed can be sized in wide margins and is governed by ECAS ~dtUS size and other operational 20 considerations. For example, a smaller bed can be thermally integrated into the a~dLus more easily but it would have less energy storage capacity. The Fe/FeO
pellets can be configured in various shapes, such as irregular lumps, spherical, oblate spheroid, annular ("Raschig rings"), wagon wheel or the like. The ~e/FeO pellets can also be comprised of il,lpl~gn~t~cl iron oxide/iron metal in high lGIlll-Glatule ceramic 25 substrates, such as ~lllmin~ ~Ul~lJOll material, or better as pure solid Fe/FeO. An active bed volume of 108-240 m3 for a 25MV electrochemical apparatus is plGfGllGd. The ~ actual volume of the Fe/FeO pellets is about 32 m3. The pellet size, shape, strength, uSity, and packing density are important parameters for effective operation in terms of size, structural, thermal and pressure drop characteristics and can be determined by 30 operational analysis. The Fe/FeO energy storage chamber 88 is coupled to recirculation CA 022ll39l l997-07-24 W 096/23322 PCTrUS96/00648 blowers 92 positioned at a low te~ )erdture region for recirculation of the gases in the recirculation ch~nn~l 84 to a gaseous feed inlet to the electrochemi-~l cells 56.
By way of example, during operation of the ECAS apparatus 50 in the electrolysis or energy storage mode, excess AC electrical energy produced from a5 power plant during off-peak hours, is converted to DC by conventional methods well known in the art and fed through the electrical leads 94 to the electrochemical cells 56 dted at a telllpe~dture above 350~C and about 600~C to 1000~C. Fresh (preheated)water vapor (steam) is fed through an inlet 78 and passes over the axial portion of the outer electrolysis cathode 58 and is electrochernic~lly reduced to H2 gas and oxygen 10 ions. The hydrogen gas produced is directed to pass from the cell chamber 70 into the recirculation ch~nnel 84. Meanwhile, the oxygen ions pass through the solid oxide electrolyte 60 and are electrochemically oxidized at the inner anode 62 to produce ~2 which is vented as a by-product at the open ends of the cells into the combustion/exh~ t chamber 80 and is eYh~ t~ to the atmosphere or recovered, if 15 possible. Make-up steam is injected through an inlet 78 into the col"l)a"",ent between porous barriers 74 and 76 to prevent H2 gas loss by reoxidation in the combustion chamber with eYh~ ted oxygen.
The H2 gas in the recirculation ch~nn~l 84 iS passed through a Fe/FeO energy storage bed 88 cont~ining FeO and reacts at ~e,.,pe~atures of about 600~C to 800~C to 20 form Fe and H2O (steam). The H2O steam is recirculated by blowers 92 in the recirculation ch~nnel 84 to the cell ch~mber 70. The steam is recirculated and electrolyzed over and over again until subst~nti~lly complete reduction of FeO to Fe and accordingly until substantially complete charging of the Fe occurs. When all the beds 88 of FeO are reduced to Fe (only one bed being shown in Fig. 3), the energy storage 25 capability is eYh~ ted Only a small amount of injected fresh steam is needed to reduce a large amount of FeO to Fe due to the recirculation of steam to the outer cathode of the electrolysis cell. Thus, in the energy storage mode, excess electrical energy produced from the power plant is stored as chemi~l energy, not in the form of bulky H2 gas, but in the form of iron (Fe) metal pellets which provide a compact and 30 recoverable energy storage arrangement.
W 096/23322 PCTrUS96/00648 When the electrical energy is needed for electrical power tr~nsmicsion from the power plant, the ECAS apparatus 50 is operated in an energy recovery mode. During operation in the fuel cell or energy recovery mode, stored chemic~l energy in the form of iron metal is converted via the oxidation of hydrogen, released from the energy 5 storage bed through oxidation of iron (Fe) through incoming steam, in the fuel cell to DC electrical energy and then converted to AC electrical energy by conventional methods for electrical power tr~n~mi~cion. Fresh (preh~t~) water vapor (steam) is fed through inlet 78 and drawn into the recirculation channel 84 by the recirculation blower 92 and then is fed over the Fe/FeO energy storage bed 88 in the previous Fe 10state at temperatures of about 600~C to 800~C to oxidize the Fe to FeO and produce H2 gas. The H2 gas produced is passed over the exterior fuel anode 58 of the electrochenlic~l cell where it electrochemically reacts along the outer axial length with oxygen ions to produce direct current electrical, heat and H2O, which is, again,circulated through channel 84 to bed 88.
15An oxidant, such as air or ~2~ typically supplied in excess for cooling and/orheat transfer, is fed through inlet 68 and is partially prehlo~tt~d while it flows through the oxidant manifold and conduits which extend down the inside length of the electrochP-mir~l cells 56 at te~ )eldtures of about 1000~C. The oxidant is discharged into the closed end (bottom) of the electrochemir~l cells and then reverses direction and 20 electrochtomic~lly reacts at the inner air ç~thode 62 along the inside of the active length of the electrochemical cells, being depleted in oxygen as it approaches the open ends 86 of the cells. The depleted or spent oxidant is discharged into the combustion/exhaust chamber 80 through the open cell ends, where it combusts with some depleted or spent hydrogen which passes through porous barriers 74 and 76 to form a hot combusted 25 exhaust gas which can be directed to pass in an exhaust channel 82 in heat comm--nic~tion with other parts of the electrochemic~l apparatus, prior to exiting into the atmosphere. Oxygen ions formed by this electrochemical reaction become a part of the solid oxide electrolyte crystal structure and migrate through the solid oxide electrolyte to the exterior fuel anode 58, where the H2 gas supplied from the FelFeO
30 energy storage reactor 88 is directed over the axially length of the fuel anode is electrochemically oxidized and electrons are released which flow through an external W O 96/23322 PCTrUS96/00648 load circuit to the air cathode, thus generating direct current electrical energy. T h e H2O (steam) produced at the fuel anode 58 during electroçhemiç~l reactions is recirculated over and over again in recirculation ch~nnel 84 to the Fe/FeO beds 88 until subst~nti~lly complete oxidation of Fe to FeO occurs, and accordingly until substantially S complete discharging of Fe occurs. Only a small amount of injected fresh steam is needed to oxidize a large amount of Fe to FeO due to the recirculation of produced steam. Since the energy recovery mode is exothermic, an excess of air is needed to cool the cells. Further, due to incomplete sealing of the porous barrier, some loss of water vapor from the recirculation gas stream and of depleted hydrogen will occur and combust with the excess air in the combustion chamber. Make-up steam is injectedthrough inlet 78 into the co-"pal l---ent between porous barriers 74 and 76 to minimize H2O and H2 loss.
Referring now to Figure 4, this figure shows the energy conversion and storage cell voltage characteristics on charge (electrolysis mode) and on discharge (fuel cell 1~ mode). The energy efficierlcy of a charge/discharge cycle depends on the current density during charge and discha ~,e. The surface area under each operating point is the power equivalent (watts). The energy equivalent is obtained by multiplying a time factor (hours). The ratio of watt x hours (input)/watt x hours (output) represents the cell energy efficiency which must also take into consideration additional losses such as gas (steam) losses, heat losses and ~ ry electrical losses from blowers, controls, etc. The system of the invention can be used as an alternative for conventional energy storage applications. The system has the additional ability to act as a natural gas operated fuel cell power plant which offers the advantage of electrochemical energy storage.
The invention having been disclosed in connection with the foregoing variations and examples, additional variations and examples will now be apparent to personsskilled in the art. The invention is not intended to be limited to the variations and examples spe~ific~lly mentioned, and accordingly reference should be made to theappended claims rather than the foregoing discussion of plefel,~d examples to assess the spirit and scope of the invention in which exclusive rights are claimed.
Claims (8)
1. A method of storing electrical energy as chemical energy and recovering electrical energy from the stored chemical energy by operating an electrochemical cell in two modes, an energy storage mode and an energy recovery mode, characterized by the steps:
I. In the energy storage mode, (a) supplying external electrical energy to electrical leads and H2O (steam) gas to a cathode of at least one electrochemical cell operating as an electrolysis cell using a solid oxide electrolyte between an anode and the cathode, said electrolysis cell operating at a temperature of between 600°C and 1200°C, to produce H2 gas along the cathode and O2 gas along the anode;
(b) passing the H2 gas produced along the cathode of the electrolysis cell into a energy storage reactor containing iron oxide operating at a temperature of between 600°C to 800°C, to produce iron metal in the energy storage reactor and H2O (steam);
(c) recirculating the H2O (steam) produced in the energy storage reactor to the cathode of the electrolysis cell to be electrolyzed; and (d) repeating steps (a) to (c) until substantially complete conversion of iron oxide to iron metal, for chemical energy storage of electrical energy;
II. In the energy recovery mode, (e) supplying H2O (steam) gas to said energy storage reactor containing iron metal operating at a temperature of between about 600°C to 800°C, to produce iron oxide in the energy storage reactor and H2 gas;
(f) passing the H2 gas to a fuel anode of the at least one electrochemical cell operating as a fuel cell, and supplying O2 gas or air to an air cathode of the at least one electrochemical cell operating at a temperature of between 600°C and 1200°C, to conduct electrical energy along the external leads and produce H2O (steam) along the fuel anode;
(g) recirculating the H2O (steam) produced at the fuel anode of the fuel cell to said energy storage bed;
(h) repeating steps (e) to (g) until substantially complete conversion of iron metal to iron oxide and H2 gas for electrical energy recovery form chemical energy storage; and, (i) recovering the electrical energy produced.
I. In the energy storage mode, (a) supplying external electrical energy to electrical leads and H2O (steam) gas to a cathode of at least one electrochemical cell operating as an electrolysis cell using a solid oxide electrolyte between an anode and the cathode, said electrolysis cell operating at a temperature of between 600°C and 1200°C, to produce H2 gas along the cathode and O2 gas along the anode;
(b) passing the H2 gas produced along the cathode of the electrolysis cell into a energy storage reactor containing iron oxide operating at a temperature of between 600°C to 800°C, to produce iron metal in the energy storage reactor and H2O (steam);
(c) recirculating the H2O (steam) produced in the energy storage reactor to the cathode of the electrolysis cell to be electrolyzed; and (d) repeating steps (a) to (c) until substantially complete conversion of iron oxide to iron metal, for chemical energy storage of electrical energy;
II. In the energy recovery mode, (e) supplying H2O (steam) gas to said energy storage reactor containing iron metal operating at a temperature of between about 600°C to 800°C, to produce iron oxide in the energy storage reactor and H2 gas;
(f) passing the H2 gas to a fuel anode of the at least one electrochemical cell operating as a fuel cell, and supplying O2 gas or air to an air cathode of the at least one electrochemical cell operating at a temperature of between 600°C and 1200°C, to conduct electrical energy along the external leads and produce H2O (steam) along the fuel anode;
(g) recirculating the H2O (steam) produced at the fuel anode of the fuel cell to said energy storage bed;
(h) repeating steps (e) to (g) until substantially complete conversion of iron metal to iron oxide and H2 gas for electrical energy recovery form chemical energy storage; and, (i) recovering the electrical energy produced.
2. The method of claim 1, characterized in that the thermal energy is supplied from external sources and the electrical energy is supplied from a power plant.
3. The method of claim 1, characterized in that said electrolysis cell anode and said fuel cathode are comprised of lanthanum manganite, said solid oxide electrolyte is comprised of yttria or scandia stabilized zirconia, and the electrolysis cell cathode and fuel cell anode are comprised of nickel-zirconia cermet.
4. The method of claim 1, characterized in that the O2 gas produced in step (a) is recovered as a useful by-product.
5. An electrochemical energy conversion and storage device operational in two modes, an energy recovery mode and an energy storage mode, characterized by:
(A) an electrochemical cell chamber, the cell chamber containing at least one electrochemical cell bundle, the cell bundle containing a plurality of parallel, axially elongated, interconnected electrochemical cells, each cell including a porous exterior electrode, a porous interior electrode, and a gas-tight solid oxide electrolyte between the two electrodes;
(B) a combustion chamber connected to the cell chamber;
(C) at least one combustion exhaust channel connected from the combustion chamber to the atmosphere;
(D) at least one energy storage chamber connected to the cell chamber, the energy storage chamber containing either iron oxide in the energy storage mode of operation or iron metal in the energy recovery mode of operation;
(E) at least one recirculation gas channel connected from outside of the porous exterior electrode in the cell chamber to the energy storage chamber;
(F) a steam inlet connected to the outside of the porous exterior electrode in the cell chamber;
(G) an oxidant inlet connected to the inside of the porous interior electrode in the cell chamber; and, (H) electrical leads connected from the cell bundles in the cell chamber to an external circuit, in which the device can be operated in an energy storage mode by supplying direct current electrical energy from the external circuit through the leads to the electrochemical cells and steam through the steam inlet to the porous exterior electrode and providing the energy storage chamber in the iron oxide state, and in which the device can be operated in an energy recovery mode by providing the energy storage chamber in the iron state and supplying steam through the steam inlet to the energy storage chamber and an oxidant through the oxygen inlet to the porous interior electrode and recovering direct current electrical energy from the electrochemical cells through the leads to the external circuit.
(A) an electrochemical cell chamber, the cell chamber containing at least one electrochemical cell bundle, the cell bundle containing a plurality of parallel, axially elongated, interconnected electrochemical cells, each cell including a porous exterior electrode, a porous interior electrode, and a gas-tight solid oxide electrolyte between the two electrodes;
(B) a combustion chamber connected to the cell chamber;
(C) at least one combustion exhaust channel connected from the combustion chamber to the atmosphere;
(D) at least one energy storage chamber connected to the cell chamber, the energy storage chamber containing either iron oxide in the energy storage mode of operation or iron metal in the energy recovery mode of operation;
(E) at least one recirculation gas channel connected from outside of the porous exterior electrode in the cell chamber to the energy storage chamber;
(F) a steam inlet connected to the outside of the porous exterior electrode in the cell chamber;
(G) an oxidant inlet connected to the inside of the porous interior electrode in the cell chamber; and, (H) electrical leads connected from the cell bundles in the cell chamber to an external circuit, in which the device can be operated in an energy storage mode by supplying direct current electrical energy from the external circuit through the leads to the electrochemical cells and steam through the steam inlet to the porous exterior electrode and providing the energy storage chamber in the iron oxide state, and in which the device can be operated in an energy recovery mode by providing the energy storage chamber in the iron state and supplying steam through the steam inlet to the energy storage chamber and an oxidant through the oxygen inlet to the porous interior electrode and recovering direct current electrical energy from the electrochemical cells through the leads to the external circuit.
6. The device of claim 5, characterized in that the electrochemical cell is tubular and said anode defines the inner walls of the tube, said cathode defines the outer walls of the tube, and said solid oxide electrolyte is between the anode and cathode.
7. The device of claim 5, characterized in that the interior electrode of theelectrochemical cell is comprised of lanthanum manganite, the solid oxide electrolyte is comprised of yttria or scandia stabilized zirconia, and the exterior electrode is comprised of nickel-zirconia cermet.
8. The device of claim 5, characterized in that the electrochemical cell is operated at temperatures between 600°C and 1200°C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/378,299 US5492777A (en) | 1995-01-25 | 1995-01-25 | Electrochemical energy conversion and storage system |
| US08/378,299 | 1995-01-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2211391A1 true CA2211391A1 (en) | 1996-08-01 |
Family
ID=23492559
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002211391A Abandoned CA2211391A1 (en) | 1995-01-25 | 1996-01-05 | An electrochemical energy conversion and storage system |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US5492777A (en) |
| EP (1) | EP0807322B1 (en) |
| JP (1) | JPH11501448A (en) |
| KR (1) | KR19980701645A (en) |
| CA (1) | CA2211391A1 (en) |
| TW (1) | TW318967B (en) |
| WO (1) | WO1996023322A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102021103883A1 (en) | 2021-02-18 | 2022-08-18 | Technische Universität Darmstadt, Körperschaft des öffentlichen Rechts | Device for temporarily storing energy |
Families Citing this family (68)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DK0780917T3 (en) * | 1995-12-19 | 2000-04-17 | Sulzer Hexis Ag | Device with fuel cells |
| WO1998015023A1 (en) * | 1996-10-03 | 1998-04-09 | Siemens Westinghouse Power Corporation | A hydrocarbon reformer for electrochemical cells |
| US5928806A (en) * | 1997-05-07 | 1999-07-27 | Olah; George A. | Recycling of carbon dioxide into methyl alcohol and related oxygenates for hydrocarbons |
| JP2001126742A (en) * | 1999-10-27 | 2001-05-11 | Sanyo Electric Co Ltd | Fuel cell electric power generating apparatus |
| US6811913B2 (en) * | 2000-11-15 | 2004-11-02 | Technology Management, Inc. | Multipurpose reversible electrochemical system |
| FR2823442B1 (en) * | 2001-04-13 | 2004-11-12 | France Telecom | PROGRAMMABLE PERFUME DELIVERY SYSTEM AND METHOD FOR IMPLEMENTING SUCH A SYSTEM |
| FR2823592B1 (en) * | 2001-04-13 | 2005-10-07 | Framatome Anp | DEVICE FOR ELECTRICALLY SUPPLYING AUXILIARY COMPONENTS OF A NUCLEAR POWER PLANT AND METHOD OF IMPLEMENTING THE SAME |
| US6620535B2 (en) * | 2001-05-09 | 2003-09-16 | Delphi Technologies, Inc. | Strategies for preventing anode oxidation |
| EP1425814B1 (en) * | 2001-06-04 | 2006-04-05 | Acumentrics Corporation | Horizontal solid oxide fuel cell tube systems and methods |
| US20030054215A1 (en) * | 2001-09-20 | 2003-03-20 | Honeywell International, Inc. | Compact integrated solid oxide fuel cell system |
| AU2003215318A1 (en) * | 2002-02-20 | 2003-09-09 | Acumentrics Corporation | Fuel cell stacking and sealing |
| DE10209309B4 (en) * | 2002-03-02 | 2004-03-11 | Mtu Cfc Solutions Gmbh | Process for inerting the anodes of high-temperature fuel cells and high-temperature fuel cell arrangement |
| FR2842892B1 (en) * | 2002-07-24 | 2005-03-18 | Centre Nat Rech Scient | INSTALLATION AND METHOD FOR THE PRODUCTION OF COLD BY A REVERSAL SORPTION SYSTEM |
| AU2003303749A1 (en) * | 2002-08-13 | 2004-11-04 | Enersol Inc., N.A., L.P. | Hydrogen odorants and odorant selection method |
| US20040126641A1 (en) * | 2002-12-27 | 2004-07-01 | Pearson Martin T. | Regenerative fuel cell electric power plant and operating method |
| US20060166070A1 (en) * | 2003-09-10 | 2006-07-27 | Ion America Corporation | Solid oxide reversible fuel cell with improved electrode composition |
| US7150927B2 (en) * | 2003-09-10 | 2006-12-19 | Bloom Energy Corporation | SORFC system with non-noble metal electrode compositions |
| JP2005255505A (en) * | 2004-03-15 | 2005-09-22 | Kurita Water Ind Ltd | Hydrogen supply method |
| WO2006014190A1 (en) * | 2004-03-16 | 2006-02-09 | The Regents Of The University Of California | Compact fuel cell |
| FR2872174B1 (en) * | 2004-06-23 | 2007-06-15 | Electricite De France | METHOD AND DEVICE FOR ELECTROLYSIS OF WATER COMPRISING A PARTICULAR ELECTRODE OXIDE MATERIAL |
| ES2285911B1 (en) * | 2005-09-05 | 2008-10-16 | Francisco Toja Silva | GENERATOR AND STORAGE PLANT OF ELECTRICAL ENERGY IN CHEMICAL FORM THROUGH HYDROGEN PRODUCTION. |
| US7491309B2 (en) | 2005-12-21 | 2009-02-17 | General Electric Company | System and method for the production of hydrogen |
| US7436922B2 (en) | 2005-12-21 | 2008-10-14 | General Electric Company | Electricity and steam generation from a helium-cooled nuclear reactor |
| US8034219B2 (en) | 2005-12-21 | 2011-10-11 | General Electric Company | System and method for the production of hydrogen |
| US8618436B2 (en) | 2006-07-14 | 2013-12-31 | Ceramatec, Inc. | Apparatus and method of oxidation utilizing a gliding electric arc |
| US7976693B2 (en) * | 2006-07-17 | 2011-07-12 | Westinghouse Electric Company Llc | Hydrogen generation process with dual pressure multi stage electrolysis |
| US7951283B2 (en) * | 2006-07-31 | 2011-05-31 | Battelle Energy Alliance, Llc | High temperature electrolysis for syngas production |
| US8350190B2 (en) | 2007-02-23 | 2013-01-08 | Ceramatec, Inc. | Ceramic electrode for gliding electric arc |
| WO2011040182A1 (en) | 2009-09-30 | 2011-04-07 | コニカミノルタホールディングス株式会社 | Fuel cell device |
| DE102009057720A1 (en) * | 2009-12-10 | 2011-06-16 | Siemens Aktiengesellschaft | Battery and method for operating a battery |
| JPWO2011077969A1 (en) | 2009-12-24 | 2013-05-02 | コニカミノルタホールディングス株式会社 | Reaction vessel and fuel cell system using the same |
| WO2011149908A2 (en) * | 2010-05-24 | 2011-12-01 | Trustees Of Boston University | System and method for energy storage and recovery |
| JP5516735B2 (en) * | 2010-07-15 | 2014-06-11 | コニカミノルタ株式会社 | Fuel cell |
| DE102010027690A1 (en) * | 2010-07-20 | 2012-01-26 | Siemens Aktiengesellschaft | Energy storage device and method for reversibly storing energy |
| EP2624354A4 (en) * | 2010-09-29 | 2014-06-04 | Konica Minolta Holdings Inc | Secondary battery type fuel cell system |
| JP5617592B2 (en) * | 2010-12-14 | 2014-11-05 | コニカミノルタ株式会社 | Secondary battery type fuel cell system |
| DE112011104575A5 (en) * | 2010-12-22 | 2013-09-19 | Siemens Ag | Electrochemical storage device for buffering electrical energy and method for operating the storage device |
| JP5640821B2 (en) * | 2011-03-02 | 2014-12-17 | コニカミノルタ株式会社 | Secondary battery type fuel cell system |
| JP5640884B2 (en) * | 2011-05-06 | 2014-12-17 | コニカミノルタ株式会社 | Secondary battery type fuel cell system |
| DE102011078116A1 (en) * | 2011-06-27 | 2012-12-27 | Siemens Ag | Energy storage and method for charging or discharging an energy storage |
| WO2013019167A1 (en) * | 2011-07-29 | 2013-02-07 | The Lutheran University Association, Inc. | Hybrid metal oxide cycle water splitting |
| US9236627B1 (en) * | 2011-09-29 | 2016-01-12 | University Of South Carolina | Solid oxide redox flow battery |
| US9130219B1 (en) | 2011-10-11 | 2015-09-08 | University Of South Carolina | Method of making redox materials for solid oxide redox flow battery |
| JP5786634B2 (en) * | 2011-10-18 | 2015-09-30 | コニカミノルタ株式会社 | Secondary battery type fuel cell |
| DE102011086260A1 (en) * | 2011-11-14 | 2013-05-16 | Siemens Aktiengesellschaft | Electrical energy storage i.e. rechargeable oxide battery, for use in power plant, has heat accumulator delivering chemical energy, where accumulator is component of guidance system and allows flow of gas in direct contact with reactant |
| JP5760983B2 (en) * | 2011-11-28 | 2015-08-12 | コニカミノルタ株式会社 | Fuel cell system |
| WO2013084623A1 (en) * | 2011-12-05 | 2013-06-13 | コニカミノルタ株式会社 | Fuel cell system |
| JP5435178B2 (en) * | 2012-01-24 | 2014-03-05 | コニカミノルタ株式会社 | Secondary battery type fuel cell system |
| WO2013111655A1 (en) * | 2012-01-26 | 2013-08-01 | コニカミノルタ株式会社 | Fuel cell system |
| DE102012205077A1 (en) | 2012-03-12 | 2013-09-12 | Siemens Aktiengesellschaft | Electric energy storage device e.g. small rechargeable oxide battery (ROB) used for stationary domestic applications, has reservoir for storing steam-hydrogen with which channels are in direct communication |
| JP5708541B2 (en) * | 2012-03-28 | 2015-04-30 | コニカミノルタ株式会社 | Tubular fuel cell connection structure and connection method, and secondary battery type fuel cell system |
| EP2810332B1 (en) * | 2012-03-29 | 2018-11-28 | Siemens Aktiengesellschaft | Electrical energy store |
| JP2013214398A (en) * | 2012-04-02 | 2013-10-17 | Konica Minolta Inc | Method of manufacturing fuel cell system |
| EP2650401A1 (en) * | 2012-04-10 | 2013-10-16 | Siemens Aktiengesellschaft | Power plant based methanation system |
| JP2014049183A (en) * | 2012-08-29 | 2014-03-17 | Konica Minolta Inc | Method of manufacturing solid oxide fuel cell |
| JP2014056674A (en) * | 2012-09-11 | 2014-03-27 | Konica Minolta Inc | Fuel cell system |
| JP5578294B1 (en) | 2012-09-19 | 2014-08-27 | コニカミノルタ株式会社 | Fuel cell system |
| KR102162095B1 (en) * | 2012-09-21 | 2020-10-07 | 크리스토퍼 로날드 그라브스 | A rechargeable carbon-oxygen battery |
| US20150288018A1 (en) * | 2012-10-23 | 2015-10-08 | Konica Minolta, Inc. | Secondary Battery Type Fuel Cell System And Manufacturing Process Therefor |
| US9285112B2 (en) * | 2013-01-29 | 2016-03-15 | University Of Kentucky Research Foundation | Method for energy storage to utilize intermittent renewable energy and low-value electricity for CO2 capture and utilization |
| US20140234735A1 (en) | 2013-02-18 | 2014-08-21 | Gong Zhang | High temperature fuel cell/electrolyzer system with energy storage media and auxiliaries outside the fuel cell power generator |
| WO2014188904A1 (en) * | 2013-05-23 | 2014-11-27 | コニカミノルタ株式会社 | Power supply system |
| DE102014002451A1 (en) | 2014-02-25 | 2015-08-27 | Forschungszentrum Jülich GmbH | Electro-chemical energy storage and method for operating the same |
| JP6767399B2 (en) * | 2016-02-04 | 2020-10-14 | Ｃｏｎｎｅｘｘ Ｓｙｓｔｅｍｓ株式会社 | Fuel cell |
| US20180019494A1 (en) * | 2016-07-12 | 2018-01-18 | Lg Fuel Cell Systems Inc. | Regeneration of fuel cell electrodes |
| EP3740601A1 (en) | 2018-01-19 | 2020-11-25 | Graves, Christopher Ronald | Passive flow battery |
| CN109879256B (en) * | 2019-03-26 | 2022-04-12 | 扬州大学 | Fe2+Electrochemical reactor with coupled cathode reduction and anode oxidation |
| CN114481175B (en) * | 2022-01-25 | 2023-09-26 | 电子科技大学 | Repairable solid symmetrical electrolytic cell device based on strontium ferrite electrode catalytic layer |
Family Cites Families (21)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE32988C (en) * | A. BERNSTEIN in Frankfurt a. M | Process for generating electrical energy | ||
| USRE28792E (en) * | 1966-03-15 | 1976-04-27 | Westinghouse Electric Corporation | Electrochemical method for separating O2 from a gas; generating electricity; measuring O2 partial pressure; and fuel cell |
| US3939257A (en) * | 1973-08-20 | 1976-02-17 | American Gas Association | Process for producing hydrogen from water |
| US3981745A (en) * | 1974-09-11 | 1976-09-21 | United Technologies Corporation | Regenerative fuel cell |
| US4087976A (en) * | 1976-08-13 | 1978-05-09 | Massachusetts Institute Of Technology | Electric power plant using electrolytic cell-fuel cell combination |
| US4204033A (en) * | 1979-01-02 | 1980-05-20 | Massachusetts Institute Of Technology | Electrical cell construction |
| US4343624A (en) * | 1979-12-10 | 1982-08-10 | Caterpillar Tractor Co. | Rotating fluidized bed hydrogen production system |
| US4395468A (en) * | 1980-12-22 | 1983-07-26 | Westinghouse Electric Corp. | Fuel cell generator |
| US4490444A (en) * | 1980-12-22 | 1984-12-25 | Westinghouse Electric Corp. | High temperature solid electrolyte fuel cell configurations and interconnections |
| US4412895A (en) * | 1981-09-29 | 1983-11-01 | Westinghouse Electric Corp. | System using SO2 as an anode depolarizer in a solid oxide electrolyte electrolysis cell for H2 production from steam |
| US4745038A (en) * | 1983-11-10 | 1988-05-17 | Westinghouse Electric Corp. | Integrated gasification iron-air electrical system |
| US4474862A (en) * | 1983-11-10 | 1984-10-02 | Westinghouse Electric Corp. | Heat rechargeable iron battery system |
| US4751152A (en) * | 1987-04-06 | 1988-06-14 | Westinghouse Electric Corp. | High bulk self-supporting electrode with integral gas feed conduit for solid oxide fuel cells |
| US4801369A (en) * | 1987-06-29 | 1989-01-31 | Westinghouse Electric Corp. | Preventing fluids in leakable enclosures from intermixing |
| US4839247A (en) * | 1987-11-13 | 1989-06-13 | International Fuel Cells Corporation | Static regenerative fuel cell system for use in space |
| US4983471A (en) * | 1989-12-28 | 1991-01-08 | Westinghouse Electric Corp. | Electrochemical cell apparatus having axially distributed entry of a fuel-spent fuel mixture transverse to the cell lengths |
| JPH03208259A (en) * | 1990-01-10 | 1991-09-11 | Mitsubishi Heavy Ind Ltd | Solid electrolyte fuel cell system |
| US5143800A (en) * | 1990-07-25 | 1992-09-01 | Westinghouse Electric Corp. | Electrochemical cell apparatus having combusted exhaust gas heat exchange and valving to control the reformable feed fuel composition |
| JP2891548B2 (en) * | 1991-01-11 | 1999-05-17 | 三菱重工業株式会社 | Power storage system using hydrogen energy |
| JPH0541236A (en) * | 1991-08-07 | 1993-02-19 | Mitsubishi Heavy Ind Ltd | Electric power storage |
| JP3253985B2 (en) * | 1991-10-11 | 2002-02-04 | 関西電力株式会社 | Power storage device |
-
1995
- 1995-01-25 US US08/378,299 patent/US5492777A/en not_active Expired - Lifetime
- 1995-12-28 TW TW084113999A patent/TW318967B/zh active
-
1996
- 1996-01-05 KR KR1019970705039A patent/KR19980701645A/en not_active Application Discontinuation
- 1996-01-05 JP JP8522923A patent/JPH11501448A/en active Pending
- 1996-01-05 CA CA002211391A patent/CA2211391A1/en not_active Abandoned
- 1996-01-05 EP EP96902158A patent/EP0807322B1/en not_active Expired - Lifetime
- 1996-01-05 WO PCT/US1996/000648 patent/WO1996023322A1/en not_active Application Discontinuation
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102021103883A1 (en) | 2021-02-18 | 2022-08-18 | Technische Universität Darmstadt, Körperschaft des öffentlichen Rechts | Device for temporarily storing energy |
Also Published As
| Publication number | Publication date |
|---|---|
| TW318967B (en) | 1997-11-01 |
| JPH11501448A (en) | 1999-02-02 |
| EP0807322A1 (en) | 1997-11-19 |
| WO1996023322A1 (en) | 1996-08-01 |
| EP0807322B1 (en) | 2000-05-31 |
| KR19980701645A (en) | 1998-06-25 |
| US5492777A (en) | 1996-02-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5492777A (en) | Electrochemical energy conversion and storage system | |
| JP2656943B2 (en) | Improved solid oxide fuel cell and assembly | |
| US5601937A (en) | Hydrocarbon reformer for electrochemical cells | |
| CA2397682C (en) | Multipurpose reversible electrochemical system | |
| US3616334A (en) | Electrically and chemically coupled power generator and hydrogen generator | |
| US8257563B2 (en) | High purity hydrogen and electric power co-generation apparatus and method | |
| EP0191229B1 (en) | Electrochemical generators | |
| AU2002219941A1 (en) | Multipurpose reversible electrochemical system | |
| JP2005518645A (en) | Fuel cell stacking and sealing | |
| US7163759B2 (en) | Solid oxide fuel cell stack assembly having tapered diffusion layers | |
| EP0551380B1 (en) | Hollow electrode for an electrochemical cell provided with at least one inlet and one outlet opening for gases, and also electrochemical cell which contains such an electrode | |
| US3432352A (en) | High temperature fuel cell having a palladium film between the anode and electrolyte | |
| US7041410B2 (en) | Fuel cell stack in a pressure vessel | |
| Rohr | High-temperature fuel cells | |
| Mogensen et al. | Fuel cells-familiar principles for electricity generation | |
| Brown | Solid oxide fuel cells | |
| JP6982586B2 (en) | Fuel cell cartridges, fuel cell modules and combined cycle systems | |
| EP0938756A1 (en) | A hydrocarbon reformer for electrochemical cells | |
| CN114335633A (en) | Near-zero carbon emission direct coal fuel cell stack power generation device and power generation method | |
| JP2022170259A (en) | fuel cell system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |