Patent Application
20050112425
The present invention relates to energy systems, and more specifically relates to high performance energy or power systems that employ electrochemical converters, such as fuel cells.
Conventional electrochemical converters, such as fuel cells, convert chemical energy derived from fuel stocks directly into electrical energy. The key components in an electrochemical converter are a series of electrolyte units having electrodes disposed over its surfaces, and a series of interconnectors disposed between the electrolyte units to provide serial electrical connections. The electrolyte units have fuel and oxidizer electrodes attached to opposite sides. Each electrolyte unit is an ionic conductor having low ionic resistance thereby allowing the transport of an ionic species from one electrode-electrolyte interface to the opposite electrode-electrolyte interface under typical converter operating conditions. Various electrolyte materials can be used, including, for example, zirconia stabilized with such compounds as magnesia, calcia or yttria are capable of satisfying the extremely high converter operating temperatures (typically around 1000° C.). The electrolyte material utilizes oxygen or oxygen-containing ions to carry electrical current. The electrolyte is typically not conductive to electrons which can cause a short-circuit of the converter. On the other hand, the interconnector is a good electronic conductor. The interaction of the reacting gas, electrode and electrolyte occurs at the electrode-electrolyte interface, which requires that the electrodes be sufficiently porous to admit the reacting gas species and to permit exit of product species.
During operation, typical fuel cells receive reactants, such as fuel and oxidizer, in respective manifolds, namely a fuel manifold and an oxidizer manifold. The fuel cell emits exhaust or resultants, such as spent fuel and the spent oxidizer, to the respective manifolds, namely the spent fuel manifold and the spent oxidizer manifold.
The fuel is distributed to the fuel electrode surface of the fuel cell units and the spent fuel is collected from downstream of the fuel electrode surface of the units. The oxidizer is distributed to the oxidizer electrode surface of the fuel cell units of the stack and the spent oxidizer is collected from downstream of the oxidizer electrode surface of the units. The spent fuel is the result of electrochemical reaction of fuel with oxidizer ionically conducted through the electrolyte.
In traditional fuel cell operation, the electrochemical reaction generates electrical voltage across the electrodes and electrical current flow from the oxidizer electrode to the fuel electrode through an external electrical load. It also produces heat according to electrochemical laws.
As is known in the art, the electrochemical converters can alternatively be operated in an electrolyzer mode, in which the electrochemical converter consumes electricity and input reactants to produce fuel.
When an electrochemical converter performs fuel-to-electricity conversion in a fuel cell mode, waste energy is generated and should be properly processed to maintain the proper operating temperature of the electrochemical device and to boost the overall efficiency of the power system. Conversely, when the device performs electricity-to-fuel conversion in the electrolyzer mode, the electrolyte must be provided with heat to maintain its reaction.
In the chemical industry, reformers typically reform hydrocarbon fuel into hydrogen-rich reformate. For example, a steam methane reformer can be used to produce hydrogen. In a steam methane reformer, hydrogen production is accomplished in several steps, including steam reforming, water gas shift reaction, and hydrogen purification. For steam reforming, hydrogen-rich gas is produced according to the following endothermic reaction:
CH4+H2OCO+3H2 ΔH=−206.16 kJ/mol CH4
Consequently, heat needs to be provided to drive the reaction and is often provided by the combustion of a fraction of the incoming natural gas feedstock (up to 25%) or from burning waste gases, such as purge gas from a hydrogen purification system. Heat transfer to the reactants can be accomplished indirectly through a heat exchanger. Methane and steam react in catalyst filled tubes. Typically, the mass ratio of steam-to-carbon is about three or more to avoid “coking” or carbon build-up on the catalysts.
Another example of a conventional reformer suitable for reforming fuel is an autothermal reformer. In autothermal reforming, a hydrocarbon fuel, such as methane or a liquid fuel, is reacted with both steam and air to produce a hydrogen-rich gas. For example, with methane, the reaction is:
CH4+H2OCO+3H2 ΔH=−206.16 kJ/mol CH4
CH4+½O2→CO+2H2 ΔH=+36 MJ/kmol CH4
With the appropriate mixture of input fuel, air and steam, the partial oxidation reaction supplies all the heat needed to drive the catalytic steam reforming reaction. Unlike a steam methane reformer, the autothermal reformer requires no external heat source and no indirect heat exchangers.
There exists a need in the art for high performance energy systems. In particular, an improved power system employing an electrochemical converter that employs structure to increase operational efficiency while concomitantly lowering costs by reducing the number of components would represent a major improvement in the industry.
The present invention provides for a hydrogen and electricity co-production (HECP) system for producing hydrogen, electricity, or a combination of both hydrogen and electricity. Specifically, the invention provides for using an electrochemical converter, such as a fuel cell, to perform multiple functions, such as reforming fuel to produce hydrogen, consuming reactants to produce electricity, or performing a combination of both, depending upon the condition of an electrical load, such as a variable electrical load, that is attached to the fuel cell.
In a typical electricity-generating mode, the fuel cell performs an electrochemical reaction by reacting a hydrogen-containing fuel with oxygen to produce electricity, water and heat. In an alternative or reformer mode, the fuel cell can be adapted to utilize heat released by an electrochemical reaction of the fuel cell to reform a hydrocarbon fuel to produce hydrogen. Furthermore, in a co-production mode, both hydrogen and electricity are co-produced by the fuel cell. The HECP system can control an amount of hydrogen and/or electricity produced and can switch between modes by varying, adjusting or controlling an electric load on the system.
According to the teachings of the present invention, a co-production energy supply system capable of producing hydrogen and electricity is contemplated. The system includes a variable electric load for varying the amount of impedance on the system, and an electrochemical converter coupled to the variable electric load. During use, the electrochemical converter produces hydrogen, electricity or both responsive to the amount of impedance introduced to the system by the variable load.
The electrochemical converter can include a high temperature fuel cell, such as a solid oxide fuel cell or a molten carbonate fuel cell. The electrochemical converter can be constructed with an electrolyte plate having a fuel electrode material disposed on one side and an oxidant electrode material disposed on an opposite side. The electrolyte plate can include an oxygen-containing ion conducting plate, a hydrogen ion conducting plate, an OH ion conducting plate, or a CO3 ion conducting plate.
According to the invention, the system can optionally include structure or means for introducing a fuel reactant and an oxidant reactant to the electrochemical converter.
According to one aspect, the variable load can be set to substantially zero to form a short-circuit across the electrodes such that no electric power is generated and oxygen-containing molecules are transported across said electrolyte plate to react with input fuel reactant to produce steam and heat, with which the remaining unspent input fuel reactant is formed into a hydrogen rich reformate, said electrochemical converter thereby functioning as a reformer.
According to another aspect, during use, oxygen-containing molecules from the input oxidant reactant can be transported across the electrolyte plate to react with the input fuel reactant with premixed steam at the fuel electrode to reform the input fuel reactant into a hydrogen rich reformate. When this occurs, the electrochemical converter functions as an autothermal reformer. Alternatively, during use, oxygen-containing molecules of the oxidant reactant can be transported across the electrolyte plate to react with the input fuel reactant without premixed steam at the fuel electrode to reform the input fuel reactant into a hydrogen rich reformate. When this occurs, the electrochemical converter functions as a partial oxidation reformer.
According to still another aspect, during use, air or relatively pure oxygen, and an input fuel reactant can be introduced to the electrochemical converter. The electrochemical converter allows oxygen-containing molecules are transported across the electrolyte plate to react with the input fuel reactant at the fuel electrode and generates heat to reform the remaining unspent input fuel reactant into a nitrogen free reformate.
According to still another aspect, the impedance of the variable electric load can be varied to vary the relative amount of or the ratio of electricity and hydrogen generated by the electrochemical converter.
During operation of the system, the variable load can introduce to the system at least a minimum impedance amount. When this occurs, the electrochemical converter reforms, primarily and only, an input fuel reactant into a hydrogen rich reformate. The minimum impedance amount can be about zero, and corresponds to a short circuit electrical arrangement across the electrochemical converter. Optionally, the variable load is adapted to introduce to the system a maximum impedance amount greater than the minimum impedance amount and which corresponds to an open circuit electrical arrangement across the electrochemical converter, in which no hydrogen or electricity is produced.
Optionally, the variable load can be adapted to introduce to the system an impedance amount that is between the maximum impedance amount and the minimum impedance amount so that the electrochemical converter produces both hydrogen and electricity. The relative amounts of the hydrogen and electricity produced by the electrochemical converter correspond to the amount of impedance introduced to the system by the variable load.
According to another aspect, the system can include structure or means for varying the impedance of the variable load so as to control the relative amount of hydrogen and electricity produced by the electrochemical converter. The means for varying can include a controller coupled to the variable load, the electrochemical converter, or both. The controller varies the amount of impedance of the variable load to control the relative amount of hydrogen and electricity produced by the electrochemical converter. Optionally, the controller can operate one or more fluid regulating devices for regulating the flow of one or more input reactants to the electrochemical converter to control the overall amount of hydrogen and/or electricity produced thereby.
The present invention also contemplates a method of co-producing hydrogen and electricity, that comprises the steps of providing a variable load for varying the amount of impedance on a system, providing an electrochemical converter capable of producing both hydrogen and electricity, and varying the impedance of the variable load to vary the relative amount of hydrogen and electricity generated by the electrochemical converter.
According to one aspect, the method can include the additional step of configuring the variable load to be able to introduce, in a reformer operational mode, at least a minimum impedance amount, where the electrochemical converter is adapted to reform, primarily and only, any unspent input fuel reactant into hydrogen when the variable load is set to the minimum impedance amount. The minimum impedance amount can be about zero, and which corresponds to a short circuit electrical arrangement.
According to another aspect, the variable load can be configured to be set to a maximum impedance amount greater than a minimum impedance amount, and which corresponds to an open circuit electrical arrangement across the electrochemical converter.
According to still another aspect, the method includes the step of configuring the variable load to be able to introduce, in a co-production operational mode, an impedance amount that is between the maximum impedance amount and the minimum impedance amount so that the electrochemical converter produces both hydrogen and electricity, where the amounts of the hydrogen and electricity produced by the electrochemical converter correspond to the amount of impedance of the variable load.
The present invention also contemplates an additional method of co-producing hydrogen and electricity, comprising the steps of performing an electrochemical reaction using a fuel cell to produce electricity; supplying heat generated by said electrochemical reaction to an electrode surface of the fuel cell, and performing a reforming process on a fuel supplied to the fuel cell using the heat generated by said electrochemical reaction.
The present invention further contemplates a method of co-producing electricity and hydrogen, comprising the steps of providing a fuel cell capable of operating in a fuel cell mode to produce electricity through an electrochemical reaction, in a reformer mode to produce hydrogen rich gas by reforming an input fuel, and in a co-production mode to produce both electricity and hydrogen, and varying the impedance of a variable load to vary the amount of at least one of hydrogen and electricity generated by the fuel cell.
The present invention further contemplates a method of producing hydrogen, comprising providing a fuel cell, providing a variable load, wherein the variable load is coupled to the fuel cell, and varying the impedance of the variable load to be substantially zero so that the fuel cell functions as a reformer to produce primarily and only hydrogen.
The present invention still further contemplates a method comprising the steps of reforming a fuel to produce hydrogen using a fuel cell; and simultaneously producing electricity using the same fuel cell.
The present invention still yet further contemplates a method, comprising the steps of co-producing electricity and hydrogen using a fuel cell, and varying a ratio of electricity to hydrogen produced by the fuel cell with a variable electric load.
The foregoing and other objects, features and advantages of the invention will be apparent from the following description and apparent from the accompanying drawings, in which like reference characters refer to the same parts throughout the different views. The drawings illustrate principles of the invention.
The present invention provides a hydrogen and electricity co-production (HECP) system that is efficient, cost-effective and flexible. The invention will be described below relative to illustrative embodiments. Those skilled in the art will appreciate that the present invention may be implemented in a number of different applications and embodiments and is not specifically limited in its application to the particular embodiment depicted herein.
As illustrated in
The unit cell of the fuel cell 12 also employs interconnector plates that are interleaved between adjacent electrode layers. The interconnectors are preferably made of an electrically and thermally conductive interconnect material. The interconnector plate can serve as the electrical connector between adjacent electrodes and as a partition between the fuel and oxidizer reactants. A fuel manifold and an oxidizer manifold are also provided to provide reactants, namely fuel and oxidizer, respectively, to each of the unit cells in the fuel cell 12. Depending upon the mode of operation, the fuel cell 12 emits resultants, the spent fuel and the spent oxidizer, to respective exhaust manifolds. Electrical connectors 36A and 36B are provided for connecting the fuel cell 12 to the external electrical load 14.
An example of a fuel cell module suitable for use with the present invention is described in U.S. Pat. Nos. 5,462,817, 5,338,622, 5,501,781, 5993,201, 5,833,822, and 5,747,185, to the inventor hereof, the contents of which are herein incorporated by reference. The illustrated fuel cell 12 exhibits excellent system scalability, power density, thermal stability and structural ruggedness than other technologies. The fuel cell 12 is further capable of operating at high operating temperatures, for example, between 600° C. and about 1000° C. While the fuel cell 12 generally requires initial external heating at startup, the electrochemical reaction is exothermic in nature, and can produce high-grade heat to drive hydrogen co-production or bottoming cycle plants, as described below. Typically, the byproduct heat from the fuel cell 12 can exceed 50% of the lower heating value of the fuel inputs.
Those of ordinary skill will readily recognize that the HECP system 10 can comprise any suitable electrochemical converter capable of producing electricity and/or hydrogen rich gas, such as a molten carbonate fuel cell and preferably a solid oxide fuel cell.
The illustrated HECP system 10 is a multi-function system. In addition to the traditional function of electrical generation, the fuel cell 12 can be utilized to perform reforming for hydrogen production or the co-production of hydrogen and electricity. In a traditional mode of operation, the fuel cell 12 generates electricity by electrochemically reacting the input fuel reactant with the input oxidant reactant to generate power, waste heat and exhaust, which includes carbon dioxide and water. In an alternative mode of reformer operation, the fuel cell 12 reforms the input fuel reactant to generate a hydrogen exhaust without simultaneously generating electricity. Additionally reactant by-products that can be included in the exhaust include carbon monoxide, carbon dioxide, and water. In a combined or co-production mode of operation, the fuel cell 12 simultaneously generates both a hydrogen exhaust, through reforming of a hydrocarbon fuel, and electricity. The exhaust can include additional reaction species such as carbon monoxide, carbon dioxide and water.
As used herein, the term “reforming” and the like refers to a chemical process performed by the fuel cell 12 that reacts hydrocarbon fuels, at an elevated temperature, such as above 250° C., and preferably between about 400° C. and about 1000° C., in the presence of steam, oxygen or both, to generate a hydrogen-rich fuel exhaust. In the present invention, the fuel cell 12 reforms hydrocarbon fuels to produce hydrogen by reacting the hydrocarbon fuel with water, and optionally oxygen, and high-grade heat.
The fuel cell 12 can switch among the different operational modes, generate electricity, produce hydrogen or vary the ratio of hydrogen to electricity produced in the combined mode, by controlling the amount of load by way of the variable load 14 that is applied to the fuel cell 12 through the electrical connectors 36A and 36B. For example, when one or more unit cells of the fuel cell 12 are arranged or placed in a short circuit electrical configuration (i.e., short-circuited), such as by varying, controlling, regulating or placing the electrical resistance or impedance of the variable load 14 to be approximately zero with the controller 24, and electric power is neither generated nor received thereby, the fuel cell operates essentially as a reformer (a simple oxygen transport membrane). If the variable load is configured to apply a non-short-circuited impedance load to the electrochemical converter, then the converter generates both hydrogen and electricity, the relative amounts of which depend upon the load impedance value. Those of ordinary skill will readily recognize that if a maximum load is applied to the fuel cell 12, such as an open circuit electrical configuration, then the fuel cell generates no electricity or hydrogen. A load amount between the maximum (open-circuit) and minimum (short-circuit) amounts, can hence be applied to the fuel cell 12 to regulate, control or vary the amount of electricity and hydrogen generated or produced by the fuel cell 12. For the sake of simplicity, hereinafter we will refer to the load 14 as a variable load, will describe the load as introducing an impedance, will describe the load or other system component as varying the impedance, and will describe the controller 24 as varying the impedance of the load.
The fuel cell 12 can alternatively operate in a “reverse” mode to produce hydrogen by splitting water. In this mode, the unit cells can function as an electrolyzer when external power is applied. The electricity used to produce hydrogen in the reverse mode can be derived from renewable energy, such as windmills, solar cells and hydropower. The use of a high-temperature SOFC as a high temperature electrolyzer is more efficient than lower temperature alkaline or proton exchange membrane (PEM) technologies, because the electrical input requirements for the electrolytic reaction at high temperature is displaced up to 30% by thermal energy according to Nernst potential. Thermal energy is a lower cost energy source than electricity by a factor of at least three or more.
With reference to
As shown, the electrical connectors 36A and 36B connect the variable load 14 to the fuel cell 12. The variable load introduces to the system an impedance amount greater than the minimum impedance amount (short-circuit) and less than the maximum impedance amount (open-circuit) to enable the converter to produce electricity. This impedance amount presented or introduced to the system can be any suitable impedance value sufficient to enable the converter to produce substantially, primarily, and only electricity with no or nominal amounts of reforming occurring (e.g., hydrogen generation). As is known to those of ordinary skill, when the variable load is set to either open-circuit or short-circuit, the electrochemical converter does not generate any electricity.
The variable load is electrically connected across at least a portion of the electrochemical converter, such as between the fuel and oxidizer electrodes. A fuel gas illustrated as a hydrocarbon fuel CH4 is supplied to a fuel electrode 32 on a first side of the oxygen-containing ion conducting electrolyte plate 30, while oxygen and nitrogen are supplied to the oxidizer electrode 34 on the second side of the electrolyte plate 30. The oxidizer electrode (cathode electrode) 34 ionizes the oxygen to form negatively charged ions. The oxygen-containing ions pass through the oxygen-containing ion conducting electrolyte plate 30 to the fuel (anode) electrode and react with the ionized hydrogen to produce carbon dioxide, water and electrons. The electrons flow through the electrical connectors 36A and 36B to power the load 14. The electrochemical reaction is an exothermic reaction that also produces heat. The water in the form of steam exits the stack as part of the exhaust or as condensed steam, and the carbon dioxide can be collected or sequestered to prevent greenhouse gas emissions if desired.
The fuel gas can comprise any suitable fuel containing hydrogen, including, but not limited, to pure hydrogen, natural gas, hydrocarbon fuels and coal.
With reference to
In the fuel cell electrochemical process, the Gibb's free energy provides the electrical energy output of the fuel cell and the balance enthalpy energy provides heat for the reforming process. The present inventor has realized that if the electric energy output is kept to zero by shorting the fuel cell or stack, the total enthalpy is available for the reforming process. This latter scenario is equivalent to the conventional autothermal or partial oxidation reformer or the membrane reformer process with the advantage of performing autothermal reforming with O2 alone without the encumbrance of N2 derived from the air supply. In this condition, oxygen-containing ions conducted through the oxygen-containing ion conducting electrolyte plate 30 immediately react with the fuel to form water and CO2 molecules, which in turn further promote reforming of the remaining fuel. The oxygen-containing ions arrival at the fuel electrode surface 32 together with heat generated by reacting with the fuel species constitute the basis for autothermal reforming of the remaining fuel species with pre-mixed steam. Oxygen mixing with unreacted fuel species without externally provided steam or water serves as the basis for partial oxidation reforming when mixing with pure fuel species.
In the reforming mode, any suitable hydrocarbon or renewable fuel may be used. The reforming mode also produces carbon dioxide, which may be easily captured for sequestration. Nitrogen, present in air, passes unreacted through the fuel cell 12 and can be released to the atmosphere. An advantage of the illustrative reforming method is that the carbon dioxide off-gas can be collected separately from the nitrogen, in contrast to conventional autothermal reformers, in which the effluent has nitrogen and carbon dioxide co-mingled.
In the reformer mode, the fuel cell 12 requires heightened thermal robustness to handle the extra thermal load which otherwise would be exported as electricity if the stack is used for power generation. The HECP system 10 of the present invention offers particular advantages and flexibility to facilitate reforming in addition to electricity production. For example, the fuel cell 12 has a relatively small reactant flow gap that allows for effective heat transfer from the heated electrode/electrolyte surface to the reactant bulk. The small reactant flow gap further allows effective heat transfer from electrode/electrolyte surface to the opposing interconnector plate. The illustrated fuel cell 12 further utilizes a highly conductive interconnector that prevents the formation of hot spots in the stack, efficiently transmits heated stream toward the inlet of the incoming reactants to provide preheating of the reactants, and efficiently transmits heat outward of the stack for radiation cooling.
With reference to
In the present invention, the ratio of electrical to hydrogen outputs can be regulated through load impedance and oxidant to fuel reactant proportioning. The controller 24 can regulate one or more of the fluid regulating devices to vary or regulate the amount of the input reactants introduced to the fuel cell 12. This regulation scheme provides an additional degree of control over the system 10, and can be used separately from or in conjunction with the foregoing control schemes (i.e., controlling the variable load 14) to vary the amount of system production. The flexibility of the HECP system 10 benefits capacity utilization as it performs electrical generation and hydrogen reforming with a single fuel cell 12.
Further explanation of the multi-mode HECP system 10 is given as an extension to the fuel cell operation. As in the energy mapping given in
As shown in
The present inventor has realized that between the minimum and maximum impedance values, the system 10 generates a varied and non-linear ratio of hydrogen to electricity as a direct function of the amount of impedance introduced to the system. For example, as illustrated by the reformer power curve 42, the fuel cell functions primarily as a reformer with increased production as the current increases to a maximum and the impedance level is essentially zero. However, as illustrated by the fuel cell power curve 44, the fuel cell 12 can function as an electricity generator with a maximum capacity at an optimal impedance value between the open-circuit mode and the short circuit mode since the electric power generation equates the product of the current and the voltage of the electrochemical device.
The elegant thermal management design and operation of the HECP system 10, advanced structured stack architecture, and heat “precuperation” provide for a highly efficient, compact and productive distributed generation plant. The electrical output of the fuel cell 12 can be best utilized by compression equipment in aid of the storage scheme for hydrogen produced using the fuel cell. The co-production capability provides a self-contained energy solution to the currently emerging hydrogen infrastructure needs. The present invention increases space efficiency allowing for a more competitive distributed generation alternative.
The illustrated HECP system 10 can alternatively include an additional tri-generation option through incorporation of an absorption chiller, water heater/boilers, microturbine or other bottoming cycle plants that can further boost the overall system efficiency and utility appeals. The respective efficiency values of the various foregoing modes are as follows:
The multi-function capability of the HECP system 10 is particularly attractive for renewable power parks and distributed generation applications. In the solid oxide electrolyzer/fuel cell modes the HECP system 10 can offer higher efficiency relative to its low temperature counterparts, resulting from reduced Nernst potential for electrolysis operation and co-generation or co-production synergies using the waste heat of the high temperature fuel cell operation. The versatility of the multi-mode functionality can allow for full capacity utilization by adapting the operation to varying business cases such as a prioritized scheme to exploit low cost renewable energy, high hydrogen demand or electric peak-shaving. Moreover, the consolidated hardware as described will be more capital and operationally efficient than combining several discrete systems to achieve the same purpose and capabilities. Due to these advantages, the HECP system 10 is envisioned to provide an exceedingly lower cost and higher capital utilization pathway toward the nation's hydrogen and energy objectives.
The combined benefits of this hybrid concept include, but are not limited to, efficiency and cost. The endothermic reforming process utilizes significant energy made available from the high grade heat discharged from the high temperature fuel cell process, resulting in greater efficiency. The ability to vary the reforming capabilities and electricity production of the fuel cell 12 avoids the need for transport of hot flows and external heat exchangers. In addition to the mode specific benefits, the multi-mode HECP system 10 can be operated at a high utilization rate. In the absences of renewable energy supply or hydrogen gas, the fuel cell 12 can continue to operate as a hydrocarbon fuel cell for power generation or as an equivalent membrane reformer for hydrogen production, or both to varying degrees. The HECP system 10, offering durable operation and full capacity utilization, is capable of achieving $0.04/kWh of electrical generation or $1.50/kg of hydrogen production.
The HECP system 10 of the present invention performs hydrogen electric co-production by directly applying within the fuel cell stack the waste heat generated by the fuel cell itself so as to provide the necessary heat for enabling the stack to reform an input fuel reactant. The system of the present invention hence uses a single fuel cell stack to function as both an electricity generating device and a reformer to achieve enhanced efficiency over systems that employ separate fuel cells and reformers. The efficiency of the illustrated system approaches the combined efficiencies of the separately operated devices.
Those of ordinary skill will readily recognize that any selected number and arrangement of electrochemical converters can be employed in the system 10 of the present invention, provided that the electrochemical converters have the capability to operate as both an electricity generating device and a reformer. During use, the electrochemical convert can operate at relatively full capacity while generating electricity, hydrogen, or both.
A significant advantage of the present invention is that the electrochemical converter of the system 10 of the present invention can be operated to satisfy peak electrical demands of the system while concomitantly utilizing any excess capacity for hydrogen production. As the hydrogen generator, the HECP system 10 offers nitrogen-free reformate for high-quality hydrogen production. The system also produces pure carbon dioxide exhaust for ease of this greenhouse gas sequestration.
It will thus be seen that the invention efficiently attains the objects set forth above, among those made apparent from the preceding description. Since certain changes may be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense.
It is also to be understood that the following claims are to cover generic and specific features of the invention described herein, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.
This application claims priority under 35 U.S.C. 119(e) to co-pending U.S. Provisional Application No. 60/509,209, entitled “Reversible Ionic Membrane Device with Autothermal Reforming for Combined Hydrogen and Power”, filed Oct. 7, 2003, the contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60509209 | Oct 2003 | US |
