Patent Publication Number: US-2023146574-A1

Title: Fuel cell systems and methods with improved fuel utilization

Description:
FIELD 
     Aspects of this disclosure relate to fuel cell systems and methods of operating a fuel cell system. 
     BACKGROUND 
     Fuel cells, such as solid oxide fuel cells, are electrochemical devices which can convert energy stored in fuels to electrical energy with high efficiencies. High temperature fuel cells include solid oxide and molten carbonate fuel cells. These fuel cells may operate using hydrogen and/or hydrocarbon fuels. There are classes of fuel cells, such as the solid oxide regenerative fuel cells, that also allow reversed operation, such that oxidized fuel can be reduced back to unoxidized fuel using electrical energy as an input. 
     SUMMARY 
     An embodiment fuel cell system includes at least one hot box including a fuel cell stack and producing an anode exhaust product, at least one hydrogen pump, at least one product conduit fluidly connecting an anode exhaust product outlet of the hot box to an inlet of the at least one hydrogen pump, a compressed hydrogen product conduit connected to a compressed hydrogen product outlet of the at least one hydrogen pump, and at least one effluent conduit connected to an unpumped effluent outlet of the at least one hydrogen pump. 
     A further embodiment fuel cell system includes at least one hot box including a fuel cell stack and producing an anode exhaust product, at least one carbon dioxide pump, at least one product conduit fluidly connecting an anode exhaust product outlet of the hot box to an inlet of the at least one carbon dioxide pump, a compressed carbon dioxide product conduit connected to a compressed carbon dioxide product outlet of the at least one carbon dioxide pump, and at least one effluent conduit connected to an unpumped effluent outlet of the at least one carbon dioxide pump. 
     A further embodiment includes a method of operating a fuel cell system that includes providing a fuel inlet stream to at least one hot box of the fuel cell system, generating an anode exhaust product stream from the at least one hot box of the fuel cell system, providing the anode exhaust product stream to at least one hydrogen pump, generating a compressed hydrogen product and an unpumped effluent in the at least one hydrogen pump, and recycling at least a portion of the compressed hydrogen product to the at least one hot box of the fuel cell system. 
     A further embodiment includes a method of operating a fuel cell system that includes providing a fuel inlet stream to at least one hot box of the fuel cell system, generating an anode exhaust product stream from the at least one hot box of the fuel cell system, providing the anode exhaust product stream to at least one carbon dioxide pump, generating a compressed carbon dioxide product and an unpumped effluent in the at least one carbon dioxide pump, and recycling at least a portion of the unpumped effluent from the carbon dioxide pump to the at least one hot box of the fuel cell system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate example embodiments of the disclosure, and together with the general description given above and the detailed description given below, serve to explain the features of the disclosure. 
         FIG.  1    is a schematic illustration of a hot box of a solid oxide fuel cell system, according to various embodiments. 
         FIG.  2    is a schematic diagram of components of a fuel cell system according to an embodiment of the present disclosure. 
         FIG.  3    is a schematic diagram of components of a fuel cell system according to another embodiment of the present disclosure. 
         FIG.  4    is a schematic diagram of components of a fuel cell system according to yet another embodiment of the present disclosure. 
         FIG.  5    is a schematic diagram of components of a fuel cell system according to yet another embodiment of the present disclosure. 
         FIG.  6    is a schematic diagram of components of a fuel cell system according to yet another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The various embodiments are described in detail with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. References made to particular examples and implementations are for illustrative purposes, and are not intended to limit the scope of the invention or the claims. 
       FIG.  1    is a schematic representation of a hot box  100  of a fuel cell system  10 , such as a solid oxide fuel cell (SOFC) system, according to various embodiments of the present disclosure. The hot box  100  may contain fuel cell stacks  102 , such as a solid oxide fuel cell stacks (where one solid oxide fuel cell of the stack contains a ceramic electrolyte, such as yttria stabilized zirconia (YSZ) or scandia stabilized zirconia (SSZ), an anode electrode, such as a nickel-YSZ or Ni-SSZ cermet, and a cathode electrode, such as lanthanum strontium manganite (LSM)). The stacks  102  may be arranged over each other in a plurality of columns. 
     The hot box  100  may also contain an anode recuperator  110 , a cathode recuperator  120 , an anode tail gas oxidizer (ATO)  130 , an anode exhaust cooler  140 , a vortex generator  550 , and a steam generator  160 . The fuel cell system  10  may further include additional components, such as a system blower  208  (e.g., air blower), a water source  206 , valve(s)  511  and/or fluid conduits  300 D,  302 A,  304 C,  306  and  308 G, as well as other components of the fuel cell system  10 , that may be located outside or partially outside of the hotbox  102 . However, the present disclosure is not limited to any particular location for each of the components with respect to the hotbox  102 . 
     A fuel stream may enter the hot box  102  and flow to the anode recuperator  110  through fuel conduit  300 D. The fuel stream may include a mixture of a hydrocarbon fuel, such as natural gas, recycled anode exhaust of the fuel cell system  10 , and optionally recycled hydrogen product, as described in further detail below. The fuel stream may be heated in the anode recuperator  110  and may flow from the anode recuperator  110  to the stacks  102  through fuel conduit  300 E. 
     The system blower  208  may be configured to provide an air stream (e.g., air inlet stream) to the anode exhaust cooler  140  through air conduit  302 A. Air flows from the anode exhaust cooler  140  to the cathode recuperator through air conduit  302 B. The air flows from the cathode recuperator  120  to the stacks  102  through air conduit  302 C. 
     Anode exhaust generated in the stacks  102  is provided to the anode recuperator  110  through anode exhaust conduit  308 A. The anode exhaust may contain unreacted fuel and may also be referred to herein as fuel exhaust. The anode exhaust located within the anode recuperator  110  may transfer heat to the incoming fuel stream flowing through the anode recuperator  110  to the stacks  102 . The anode exhaust may be provided from the anode recuperator  110  to anode exhaust conduit  308 B. The anode exhaust may flow through the anode exhaust conduit  308 B to the anode exhaust cooler  140 . Anode exhaust from the anode exhaust cooler  140  may exit the hot box  100  by anode exhaust conduit  308 C. An anode recycle blower (not shown in  FIG.  1   ) in fluid communication with anode exhaust conduit  308 C may be configured to move anode exhaust though anode exhaust conduit  308 C, as discussed in further detail below. In some embodiments, a splitter  511  may be configured to selectively provide a portion of the anode exhaust from the anode exhaust conduit  308 C to anode exhaust conduit  308 D. The splitter  511  may be, for example, a computer- or operator-controlled valve or any other suitable fluid splitting device, such as a passive splitter containing openings or slits in a fluid conduit. Anode exhaust conduit  308 D may selectively redirect a portion of the anode exhaust exiting the anode exhaust cooler  140  through the anode exhaust conduit  308 D to the ATO  130 , such as during startup or other transient operating states of the SOFC system  10 . 
     In the embodiment shown in  FIG.  1   , all of the anode exhaust in the hot box  100  passes through the anode exhaust cooler  140  before it exits the hot box  100  via anode exhaust conduit  308 C. In other embodiments, described in further detail below, at least a portion of the anode exhaust may exit the hot box  100  before it passes through the anode exhaust cooler  140 . For example, a portion of the anode exhaust stream may exit the hot box  100  via an anode exhaust conduit (not shown in  FIG.  1   ) that may be located between the anode recuperator  110  and the anode exhaust cooler  140 . 
     Cathode exhaust generated in the stacks  102  flows to the ATO  130  through exhaust conduit  304 A. The vortex generator  550  may be disposed in exhaust conduit  304 A and may be configured to swirl the cathode exhaust. Anode exhaust conduit  308 D may be fluidly connected to cathode exhaust conduit  304 A or the ATO  130 , downstream of the vortex generator  550 . The swirled cathode exhaust may mix with anode exhaust from anode exhaust conduit  308 D before being provided to the ATO  130 . The mixture may be oxidized in the ATO  130  to generate ATO exhaust. The ATO exhaust flows from the ATO  130  to the cathode recuperator  120  through exhaust conduit  304 B. The ATO exhaust flows from the cathode recuperator and out of the hot box  100  through exhaust conduit  304 C. 
     Water flows from a water source  206 , such as a water tank or a water pipe, to the steam generator  160  through water conduit  306 . The steam generator  160  injects water into anode exhaust conduit  308 B. Heat from the anode exhaust provided to the exhaust conduit  308 B from the anode recuperator  110  vaporizes the water to generate steam. The steam mixes with the anode exhaust to provide a humidified anode exhaust stream which flows from the anode exhaust conduit  308 B through the anode exhaust cooler  140  and into the anode exhaust conduit  308 C. 
     The system  10  may further include a system controller  225  configured to control various elements of the system  10 . The controller  225  may include a central processing unit configured to execute stored instructions. For example, the controller  225  may be configured to control fuel and/or air flow through the system  10 , according to fuel composition data. The system  10  may also include one or more fuel reforming catalysts  112 ,  114 , and  116 . 
     During operation, the stacks  102  generate electricity using the provided fuel and air, and generate the anode exhaust (i.e., fuel exhaust) and the cathode exhaust (i.e., air exhaust). The anode exhaust may contain hydrogen, water vapor, carbon monoxide, carbon dioxide, some unreacted hydrocarbon fuel such as methane, and other reaction by-products and impurities. 
       FIG.  2    is a schematic diagram of components of a fuel cell system  10  according to embodiments of the present disclosure. The fuel cell system  10  may include at least one hot box  100 , such as the hot box  100  described above with reference to  FIG.  1   . For example, a fuel cell system  10  may include n hot boxes  100 , where n is an integer between 1 and 100, such as 2 to 10, for example 4 to 8. The fuel cell system  10  illustrated in  FIG.  2    includes two hot boxes  100 , although a fuel cell system according to various embodiments may include a greater or lesser number of hot boxes  100 . 
       FIG.  2    schematically illustrates the flows of fuel and anode exhaust throughout the fuel cell system  10  according to an embodiment of the present disclosure. Referring to  FIG.  2   , the system  10  may be coupled to a fuel source  400  that may provide the fuel cell system  10  with a suitable fuel. The fuel source  400  may include one or more fuel storage containers (e.g., fuel tank(s) or similar vessels) that may be located on the same site as the system  10 . Alternatively, the fuel source  400  may provide fuel to the system  10  from a remote source, such as over a gas utility line. The fuel provided to the fuel cell system  10  from the fuel source  400  may include any suitable hydrocarbon fuel, including but not limited to methane, natural gas which contains methane with hydrogen and other gases, propane or other biogas, or a mixture of a carbon fuel, such as carbon monoxide, oxygenated carbon containing gas, such as methanol, or other carbon containing gas with a hydrogen containing gas, such as water vapor, H 2  gas or their mixtures. For example, the mixture may comprise syngas derived from coal or natural gas reformation. 
     In some embodiments, the fuel from the fuel source  400  may undergo one or more pre-processing steps before being provided to the hot boxes  100  of the fuel cell system  10 . For example, a fuel inlet conduit  300 A coupled to the fuel source  400  may provide the fuel to one or more pre-processing units  400 , such as one or more desulfurizers, to remove sulfur and/or other undesirable impurities from the fuel stream. The pre-processed fuel may then flow through fuel conduits  308 B to each of the hot boxes  100 . 
     In some embodiments, each hot box  100  may additionally include a catalytic partial oxidation (CPOx) reactor  200 , a mixer  210 , a CPOx blower  204  (e.g., air blower), and an anode recycle blower  212 , which may be disposed outside of the hot box  100 . However, the present disclosure is not limited to any particular location for each of the components with respect to the hot box  100 . 
     Referring again to  FIG.  2   , each CPOx reactor  200  that is associated with a respective hot box  100  may receive an inlet fuel stream through a fuel conduit  308 B. The CPOx blower  204  may provide air to the CPOx reactor  204 . The fuel and/or air from the CPOx reactor  200  may be provided to the mixer  210  by fuel conduit  300 C. The mixer  210  may be configured to mix the fuel stream with recycled anode exhaust from the hot box  100 . This mixture of fresh fuel and recycled anode exhaust may then be provided to the hot box  100  via fuel conduit  300 D as described above with reference to  FIG.  1   . 
     The anode exhaust (i.e., fuel exhaust) from each hot box  100  may exit the hot box  100  through anode exhaust conduit  308 C, as discussed above with reference to  FIG.  1   . A splitter  511  (see  FIG.  1   ) may selectively redirect a portion of the anode exhaust located in anode exhaust conduit  308 C back into the hot box  100  via anode exhaust conduit  308 D. As previously discussed, the portion of the anode exhaust that is redirected through anode exhaust conduit  308 D may be provided to the ATO  130  of the hot box  100  during startup or other transient operating conditions. 
     In the embodiment shown in  FIG.  2   , the remaining anode exhaust located in anode exhaust conduit  308 C may be provided to a splitter  403 . The splitter  403  may be, for example, a computer- or operator-controlled valve or any other suitable fluid splitting device, such as a passive splitter containing openings or slits in a fluid conduit. A first portion of the anode exhaust may be provided from the splitter  403  to the anode recycle blower  212  via anode exhaust conduit  308 E. The anode recycle blower  212  may be any suitable fluid (e.g., gas) blower, pump, compressor, or the like. The first portion of the anode exhaust may be provided from the anode recycle blower  212  to the mixer  210  by anode exhaust conduit  308 F. As discussed above, the recycled anode exhaust may mix with fresh fuel in the mixer  210  before reentering the hot box  100  via fuel conduit  300 D. As used herein, the portion of the anode exhaust that exits the hot box  100  via the anode exhaust conduit  308 C and is recycled by the anode recycle blower  212  to mix with fresh fuel in the mixer  210  and reenters the hot box  100  via fuel conduit  300 D may be referred to as the “anode recycle”, and the fluid pathway of the anode recycle between the anode exhaust conduit  308 C at the outlet of the hot box  100  and the fuel conduit  300 D at the inlet of the hot box  100  may be referred to as the “anode recycle loop.” 
     A second portion of the anode exhaust may be provided from the splitter  403  to a manifold  104  via anode exhaust conduit  308 G. The manifold  104  may be connected to plural hot boxes  100  of the system  10 , including, in some embodiments, to all of the hot boxes  100  of the system  10 , by respective anode exhaust conduits  308 G. Alternatively, the system  10  may include multiple manifolds  104 , where each manifold  104  may be connected to a sub-set of hot boxes  100  of the system  10 . In various embodiments, anode exhaust streams from plural hot boxes  100  of the system  10  may be combined in the manifold  104 . 
     Referring once again to  FIG.  2   , in some embodiments, each of the hot boxes  100  may include an optional additional anode exhaust conduit  308 H that is in fluid communication with the manifold  104 . In some embodiments, the optional additional anode exhaust conduit  308 H may provide a direct fluid pathway between the hot box  100  and the manifold  104 . In some embodiments, the anode exhaust within the optional anode exhaust conduit  308 H may exit the hot box  100  upstream of the anode exhaust cooler  104  (see  FIG.  1   ). For example, the hot box  100  may include a splitter (e.g., a valve, a passive splitter, or the like) within anode fluid conduit  308 B located between the anode recuperator  110  and the anode exhaust cooler  140  in the hot box  100  shown in  FIG.  1   . The splitter may divert a portion of the anode exhaust stream from anode exhaust conduit  308 B to optional anode exhaust conduit  308 H such that this portion of the anode exhaust stream may be provided directly to the manifold  104  shown in  FIG.  2   . The remaining portion of the anode exhaust stream may proceed through the anode exhaust cooler  140  and into anode exhaust conduit  308 C as described above. 
     Accordingly, in some embodiments, the anode exhaust provided to the manifold  104  may include a first component of anode exhaust that exits the hot box  100  at the outlet of the anode exhaust cooler  140  and flows through anode exhaust conduit  308 C, splitter(s)  511  and/or  403 , and anode exhaust conduit  308 G to the manifold  104 , and a second component of anode exhaust that exits the hot box  100  upstream of the anode exhaust cooler  140  and flows through anode exhaust conduit  308 H to the manifold  104 . Accordingly, the second component of the anode exhaust may bypass the anode exhaust cooler  140 , and therefore may have a higher temperature than the first component of the anode exhaust that flows through the anode exhaust cooler  140 . 
     In some embodiments, the mixture of anode exhaust that is received in the manifold  104  may be variable, such that during certain times, a greater portion of the anode exhaust, including all of the anode exhaust, that is provided from one or more hot boxes  100  to the manifold  104  may be the first component of the anode exhaust provided via anode exhaust conduit  308 G (i.e., anode exhaust that has passed through the anode exhaust cooler  140  of the hot box  100 ), and at other times, a greater portion of the anode exhaust, including all of the anode exhaust, that is provided from the one or more hot boxes  100  to the manifold  104  may be the second component of the anode exhaust provided via anode exhaust conduit  308 H (i.e., anode exhaust that has bypassed the anode exhaust cooler  140  of the hot box  100 ). The system controller  225  as described above with reference to  FIG.  1    may be used to control the mixture of the first and second components of the anode exhaust that is provided to the manifold  104  from each of the hot boxes  100 . 
     In some embodiments, the first component of the anode exhaust that is provided to the manifold  104  via anode exhaust conduit  308 G (i.e., anode exhaust that has passed through the anode exhaust cooler  140  of the hot box  100 ), may have a temperature of between about 100° C. and 180° C., and the second component of the anode exhaust that is provided to the manifold  104  via anode exhaust conduit  308 H (i.e., anode exhaust that bypasses the anode exhaust cooler  140  of the hot box  100 ) may have a temperature of between about 300° C. and 500° C. 
     Accordingly, by providing an anode exhaust stream that includes a mixture of a lower-temperature first component of anode exhaust that passes through the anode exhaust cooler  140  of a hot box  100  and a higher-temperature second component of anode exhaust that bypasses the anode exhaust cooler  140 , the temperature of the anode exhaust in the manifold  104  may be controllably varied. In some embodiments, the temperature of the anode exhaust in the manifold  104  may be controlled to include more heat than is required for subsequent H 2  recovery and/or CO 2  separation processes as described in further detail below. Providing an anode exhaust stream containing excess heat may provide an advantage in that cooling of the anode exhaust as needed for one or more subsequent processes may consume less parasitic power than would be required to heat the anode exhaust for these same processes. 
     Referring again to  FIG.  2   , the combined anode exhaust streams from multiple hot boxes  100  may be provided from the manifold  104  to an anode exhaust conditioning unit  404  via anode exhaust conduit  308 I. The anode exhaust conditioning unit  404  may be configured to modify a temperature of the anode exhaust stream to make the anode exhaust stream suitable for introduction to a water gas shift (WGS) reactor  405  located downstream of the anode exhaust conditioning unit  404 . The anode exhaust conditioning unit  404  may include one or more heat transfer devices, such as one or more heat exchangers and/or condensers. Other suitable heat transfer devices are within the contemplated scope of the disclosure. In some embodiments, where the temperature of the anode exhaust stream is greater than an operating temperature range of the WGS reactor, the one or more heat transfer devices may be cooled by a cooling medium, such as cooling water and/or air, in order to reduce a temperature of the anode exhaust stream flowing through the anode exhaust conditioning unit  404 . In other embodiments, where the temperature of the anode exhaust stream is lower than an operating temperature range of the WGS reactor  405 , the one or more heat transfer devices may transfer heat to the anode exhaust stream in order to increase a temperature of the anode exhaust stream flowing through the anode exhaust conditioning unit  404 . Heat transfer to the anode exhaust stream may be achieved by heat exchange with a fluid medium having a higher temperature than the anode exhaust stream (e.g., a combustion gas), or by using a heater, such as an electric heater, to directly heat the anode exhaust stream. In various embodiments, the temperature of the anode exhaust exiting the anode exhaust conditioning unit  404  may be between about 150° C. and 300° C., such as between about 200° C. and 250° C. 
     Referring again to  FIG.  2   , the anode exhaust stream may be provided from the anode exhaust conditioning unit  404  to the WGS reactor  405  via anode exhaust conduit  308 J. The WGS reactor  405  may be configured to convert CO and H 2 O in the anode exhaust to CO 2  and H 2  using a water-gas shift reaction. In various embodiments, the WGS reactor  405  may be a low temperature WGS reactor  405  and may have a nominal operating temperature between about 200° C. and 250° C. Following the water-gas shift reaction, the anode exhaust stream may include primarily H 2 O, CO 2  and H 2 , with smaller amounts of CO, N 2  and other impurities. 
     The anode exhaust stream may then be provided from the WGS reactor  405  to a condenser  406  via anode exhaust conduit  308 K. The condenser  406  may be cooled by a cooling medium, such as cooling water and/or air to condense water vapor to liquid water and to reduce the temperature of the anode exhaust stream to below 100° C., such as between 50° C. and 80° C. (e.g., −70° C.). The liquid water may be removed from the condenser  406  via a water exhaust conduit  407 , and the liquid water in conduit  407  may optionally be purified and/or reused. In various embodiments, water knockout may be integrated into the design of the condenser  406  or included as a separate component downstream of the condenser  406 . The partially dehydrated anode exhaust stream may be provided from the condenser  406  to at least one hydrogen pump  408  via anode exhaust conduit  308 L. 
     In various embodiments, the partially hydrogenated anode exhaust stream that is provided to the at least one hydrogen pump  408  may include at least about a 40% molar fraction of H 2 O, such as a 50-60% (e.g., ˜56%) molar fraction of H 2 O, at least about a 20% molar fraction of CO 2 , such as a 25-35% (e.g., ˜29%) molar fraction of CO 2 , at least about a 10% molar fraction of H 2 , such as a 10-20% (e.g., ˜14%) molar fraction of H 2 , a less than 1% molar fraction of CO, and a less than 1% molar fraction of N 2 . Depending on the tolerance of the at least one hydrogen pump  408  to CO, in some embodiments, the molar fraction of CO in the anode exhaust stream may be between 0.5% and 1%. This may enable relatively higher temperature operation of the WGS reactor  405  and may enable a larger thermal window of operation for the WGS reactor  405 . 
     The at least one hydrogen pump  408  may include an electrochemical hydrogen pump or pumps. The at least one electrochemical hydrogen pump  408  may include a hydrogen pump and a separator which electrochemically pumps pure hydrogen through a polymer membrane upon application of a current or voltage across the membrane. In various embodiments, the at least one electrochemical hydrogen pump  408  may include a high-pressure hydrogen separation and compression system available from Skyre, Inc. under the name “H2RENEW™” and/or described in U.S. Pat. Nos. 10,756,361 and/or 10,648,089. The at least one hydrogen pump  408  may include multiple pumps (e.g., plural separation membrane stacks) connected in series and/or in parallel to enable a higher overall recovery fraction of hydrogen and/or a higher throughput. In some embodiments, the at least one hydrogen pump  408  may be tolerant to at least about 0.5% molar fraction of CO, including up to about 1% molar fraction of CO, in the dehydrated anode exhaust stream provided to the at least one hydrogen pump  408 . 
     In one embodiment, the at least one hydrogen pump  408  may recover greater than 80% of the hydrogen in the dehydrated anode exhaust stream and output greater than 99% pure compressed hydrogen product through a compressed hydrogen product conduit  410 . For example, the compressed hydrogen product may be at least 99.99% pure (i.e., dry) hydrogen which may be pressurized to a pressure 1 psig to 10,000 psig, such as 15 psig to 2,000 psig, for example 15 psig to 150 psig. In various embodiments, the compressed hydrogen product produced by the at least one hydrogen pump  408  may be suitable for use or storage without additional mechanical compression or drying. 
     Referring again to  FIG.  2   , compressed hydrogen product in compressed hydrogen product conduit  410  may be provided to a splitter  411 . The splitter  411  may be, for example, a computer- or operator-controlled valve or any other suitable fluid splitting device, such as a passive splitter containing openings or slits in a fluid conduit. A first portion of the compressed hydrogen product may be provided from the splitter  403  to a hydrogen recycle conduit  412 A for further use in the fuel cell system  10 . A second portion of the compressed hydrogen product may be provided from the splitter  403  to a hydrogen storage conduit  413  for storage and/or distribution or sale of the compressed hydrogen product. In some embodiments, the hydrogen storage conduit  413  may provide the compressed hydrogen product directly to one or more hydrogen storage containers  414  connected to the hydrogen storage conduit  413 . Alternatively, one or more compressors (not shown in  FIG.  2   ) may be coupled to the hydrogen storage conduit and may be configured to further compress the compressed hydrogen product to a pressure suitable for storage in the one or more hydrogen storage containers  414 . 
     In various embodiments, hydrogen recycle conduit  412 A may be used to provide compressed hydrogen product to one or more locations in the fuel cell system  10 . In some embodiments, the hydrogen recycle conduit  412 A may provide at least a portion of the compressed hydrogen product to the fuel source  400 , which may be, for example, a natural gas supply. 
     Alternatively, or in addition, in some embodiments, at least a portion of the compressed hydrogen product may be provided to the inlet fuel stream for the fuel cell system  10 . In some embodiments, the compressed hydrogen product may be provided to the inlet fuel downstream of the one or more pre-processing units  400  (e.g., desulfurizer(s)) of the fuel cell system  10 . In one embodiment shown in  FIG.  2   , a splitter  415  may direct at least a portion of the compressed hydrogen product from hydrogen recycle conduit  412 A to hydrogen recycle conduit  412 B, which may provide the at least a portion of the compressed hydrogen product to fuel inlet conduit  300 A. 
     Alternatively, or in addition, in some embodiments, at least a portion of the compressed hydrogen product may be provided to the anode recycle loops of one or more of the hot boxes  100 . In various embodiments, compressed hydrogen product may be provided to the anode recycle loops of all of the hot boxes  100  of the fuel cell system  10 . In one embodiment shown in  FIG.  2   , one or more splitters  416  may direct at least a portion of the compressed hydrogen product from hydrogen recycle conduit  412 A to one or more hydrogen recycle conduits  412 C. Each of the anode recycle conduits  412 C may be fluidly connected to the anode recycle loop of a respective hot box  100 . The compressed hydrogen product provided to the anode recycle loop of a hot box  100  may mix with both the anode recycle and fresh fuel in the anode recycle loop, and may enter the hot box  100  via fuel conduit  300 D. 
     In some embodiments, at least a portion of the compressed hydrogen product may also be provided to the ATO  130  of one or more hot boxes  100  of the fuel cell system  10 . In embodiments, compressed hydrogen product may be provided to the ATO  130  during startup of the hot box  100  or other transient conditions, and may be used for thermal management of the hot boxes  100 . In the embodiment shown in  FIG.  2   , one or more hydrogen recycle conduits  412 D may selectively redirect a portion of the compressed hydrogen product to the ATO  130  of one or more respective hot boxes  100 . In some embodiments, the hydrogen recycle conduits  412 D may be fluidly coupled to anode exhaust conduits  308 D for directing compressed hydrogen product to the respective ATOs  130 . By providing hydrogen to ATO  130 , the temperature of hot box  100  is maintained at a near constant temperature, or as near to constant as is feasible or practical. Given the other changes (e.g., ambient temperature changing, purposeful air flow changes, etc.), there is no predetermined flow control of the feed stream to ATO  130 . In some configurations, a proportional solendoid valve may be used to control the flow to +/−3-5%. Other configurations may achieve further control of the the flow (e.g. +/−0.5%), but such other configurations are expensive. 
     In embodiments, the compressed hydrogen product may be sufficiently pure (i.e., dry) that it may be recycled for use in the fuel cell system  10  without requiring any additional processing or conditioning. In addition, in some embodiments the dry compressed hydrogen product may be provided to various components/locations of the fuel cell system  10  without requiring the conduits  412 A,  412 B,  412 C,  412 D carrying the compressed hydrogen product to be traced and insulated to avoid water condensation. The dry compressed hydrogen product may also not produce condensation in unwanted locations of the fuel cell system  10 , such as in desulfurization tanks. 
     In instances in which the compressed hydrogen product is not sufficiently dry for use in the fuel cell system  10  or a component thereof, a refrigerated condenser may optionally be used to further reduce the water content of the compressed hydrogen product before the compressed hydrogen product is used in the fuel cell system  10 . 
     In various embodiments, the system controller  225  (see  FIG.  1   ) may control the amount of compressed hydrogen product provided to various locations in the fuel cell system  10  and/or to the one or more hydrogen storage containers  414 . In one non-limiting example, during steady-state operation of the fuel cell system  10 , all or nearly all of the compressed hydrogen product may be provided to the hot boxes  100  of the fuel cell system  10 . Any excess compressed hydrogen product not required for operation of the fuel cell system  10  may be provided to the one or more hydrogen storage containers  414 . An advantage of recycling the majority of the compressed hydrogen product to the fuel cell system  10  is that the need to meet precise and high fuel utilization targets for the fuel cell system  10  may be lessened as more hydrogen product is recycled as a fuel. With the provision of a relatively large quantity of recycled hydrogen product, lower per pass utilization can still support a high overall fuel utilization for the fuel cell system  10 . In addition, by lowering the fuel utilization of the fuel cell system  10  as desired, the quantity of hydrogen product that is provided to the one or more hydrogen storage containers  414  may be increased. 
     Referring again to  FIG.  2   , the unpumped effluent from the at least one hydrogen pump  408  may contain mainly water (e.g., water vapor and/or liquid water) and carbon dioxide. The unpumped effluent may also contain a small amount of hydrogen that was not separated from anode exhaust, as well as smaller amounts of carbon monoxide, nitrogen, and other impurities. For example, the unpumped effluent may contain less than a 10% molar fraction of H 2 , such as 0-5% molar fraction of H 2 , a 0-1% molar fraction of CO, and a 0-1% molar fraction of nitrogen. Liquid water may optionally be removed from the at least one hydrogen pump  408  via a water exhaust conduit  417 , and the liquid water in conduit  417  may optionally be purified and/or reused. The unpumped gaseous effluent from the at least one hydrogen pump  408  may be provided from the at least one hydrogen pump  408  to effluent conduit  418 . 
     In some embodiments, the effluent from the at least one hydrogen pump may optionally be fed from effluent conduit  418  to a blower  419 , which may be any suitable fluid (e.g., gas) blower, pump, compressor, or the like. The blower  419  may “pull” the unpumped effluent from the at least one hydrogen pump  408 . The blower  419  may further compress the effluent, such as to a pressure between 2-15 psig. The heat of compression of the unpumped effluent may raise the temperature of the unpumped effluent. This may pre-heat the effluent for a subsequent catalytic or thermal reaction configured to oxidize some or all of the residual H 2  and CO in the effluent. The compression of the effluent may also decouple the compression from CO 2  compression, dehydration and/or liquification processes that may subsequently be performed. In embodiments in which optional blower  419  is present, the compressed effluent from the blower  419  may be provided to effluent conduit  420 . In some instances, adjusting a large compressor (i.e., varying the compressor speed) that has a high compression ratio may be difficult. For example, small changes in compressor speed may pull too much or too little gas from the pipe, causing pressure disturbances upstream. However, a small blower has a lower gain, and small adjustments in speed have small changes in flowrate and inlet pressure. In some instances, a small storage volume downstream of a blower may be used to provide some capacitance to the system for pressure control. For example, downstream storage volume may be on the order of one minute of residence time. 
     In various embodiments, the compressed effluent from the blower  419  may optionally be provided to an oxidation reactor  421  via effluent conduit  420 . The oxidation reactor  421  may be a catalytic or a thermal oxidation reactor that may be configured to reduce or eliminate the residual H 2  and CO content from the effluent prior to subsequent CO 2  processing steps. An oxygen source  422  may be coupled to the oxidation reactor  421  and may provide oxygen for the oxidation reaction. In some embodiments, the oxygen source  422  may include an air blower. Alternatively, or in addition, the oxygen source  422  may be an oxygen generator or an oxygen storage apparatus that may provide purified oxygen for the oxidation reaction. In embodiments in which an optional oxidation reactor  421  is present, the effluent from the oxidation reactor  421 , which may be composed substantially entirely of H 2 O and CO 2 , may be provided to effluent conduit  423 . 
     In some embodiments, the system  10  may optionally include a carbon dioxide processing device  424  that may be operatively connected to an effluent conduit  418 ,  420  and/or  423  containing effluent product from the at least one hydrogen pump  408 . The carbon dioxide processing device  424  may operate to compress and/or cool the effluent stream received from the at least one hydrogen pump  408 , which may optionally be compressed by blower  419  and/or undergo an oxidation reaction in oxidation reactor  421 . The optional carbon dioxide processing device  424  may be a condenser and/or dryer configured to remove water from the effluent stream. In some embodiments, the optional carbon dioxide processing device  424  may also convert the effluent stream into a liquified CO 2  product. The water that is removed from the effluent stream may optionally be removed from the carbon dioxide processing device  424  via a water exhaust conduit  425  for optional purification and/or reuse. The remaining portion of the effluent stream, which may include purified or pure CO 2 , may be provided to one or more CO 2  storage containers  427  via conduit  426  for storage and/or sequestration of the CO 2 , or may be used for chemical processes, beverage carbonation, etc. In some embodiments, the one or more CO 2  storage containers may include one or more cryogenic storage devices configured to convert the CO 2  into dry ice for storage. 
       FIG.  3    schematically illustrates a fuel cell system  20  according to another embodiment of the present disclosure. The fuel cell system  20  of  FIG.  3    may be similar to fuel cell system  10  described above with reference to  FIG.  2   . Thus, repeated discussion of like components is omitted for brevity. The fuel cell system  20  of  FIG.  3    may differ from the fuel cell system  10  of  FIG.  2    in that lower pressure and higher pressure hydrogen pumps may be used to recover hydrogen product. 
     In particular, referring to  FIG.  3   , a splitter  450  (e.g., a valve, a passive splitter, or the like) located in anode exhaust conduit  308 L may direct a portion of the partially hydrated anode exhaust stream to anode exhaust conduit  451 . The remaining portion of the partially hydrated anode exhaust stream in anode exhaust conduit  308 L may be provided to at least one low pressure hydrogen pump  452 . The at least one low pressure hydrogen pump  452  may be configured to pump hydrogen that is separated from the anode exhaust stream to a relatively low pressure (e.g., 1-150 psig). In various embodiments, the at least one low pressure hydrogen pump  452  may pump the hydrogen to a pressure that is suitable for use in the fuel cell system  20 . The compressed hydrogen product from the at least one low pressure hydrogen pump  452  may be provided to hydrogen recycle conduit  412 A for further use in the fuel cell system  20  as described above with reference to  FIG.  2   . The remaining effluent from the at least one low pressure hydrogen pump  452  may be provided to effluent conduit  418 , and may proceed to the optional blower  419 , the optional oxidation reactor  421 , and the optional carbon dioxide processing device  424  for separation of CO 2  as described above with reference to  FIG.  2   . Liquid water from the effluent may optionally be recovered via water exhaust conduit  453 . 
     Referring again to  FIG.  3   , the portion of the partially hydrated anode exhaust stream located within anode exhaust conduit  451  may be provided to at least one high pressure hydrogen pump  454 . The at least one high pressure hydrogen pump  454  may be configured to pump hydrogen that is separated from the anode exhaust stream to a relatively high pressure (e.g., 200 to 10,000 psig). In various embodiments, the at least one high pressure hydrogen pump  452  may pump the hydrogen to a pressure that is suitable for purposes of hydrogen storage and/or commercial sale of the purified hydrogen product. The compressed hydrogen product from the at least one high pressure hydrogen pump  454  may be provided to one or more hydrogen storage containers  414  via hydrogen product conduit  456 . The remaining gaseous effluent from the at least one high pressure hydrogen pump  454  may be provided to effluent conduit  457 , and liquid water from the effluent may optionally be recovered via water exhaust conduit  453 . In some embodiments, effluent conduit  457  may provide the effluent from the at least one high pressure hydrogen pump  454  to the optional blower  419 , the optional oxidation reactor  421 , and the optional carbon dioxide processing device  424  for separation of CO 2  as described above with reference to  FIG.  2   . 
     In general, hydrogen product intended for storage and/or commercial sale may require a higher degree of pressurization than the hydrogen product that is recycled for use in the fuel cell system  20 . In various embodiments, by providing at least one low pressure hydrogen pump  452  and at least one high pressure hydrogen pump  454  that may process the anode exhaust stream in parallel, the compressed hydrogen product recovered from the anode exhaust of the fuel cell system  20  may be optimized for different uses. In some embodiments, one or more buffer tanks (not shown in  FIG.  3   ) may be provided upstream of the at least one low pressure hydrogen pump  452  and/or the at least one high pressure hydrogen pump  454  to mitigate against fluctuations in the flow rates of the parallel anode exhaust streams feeding the respective hydrogen pumps  452 ,  454 . 
     Accordingly, the fuel cell systems  10 ,  20  shown in  FIGS.  1 - 3    may use or recapture essentially all of the hydrogen content and essentially all of the carbon content of the input fuel that is provided to the fuel cell system  10 ,  20 . This may provide increased fuel utilization for the fuel cell systems  10 ,  20 . 
       FIG.  4    schematically illustrates a fuel cell system  30  according to another embodiment of the present disclosure. The fuel cell system  30  of  FIG.  4    may be similar to fuel cell systems  10  and  20  described above with reference to  FIGS.  2  and  3   . Thus, repeated discussion of like components is omitted for brevity. The fuel cell system  30  of  FIG.  4    may differ from the fuel cell systems  10  and  20  of  FIGS.  2  and  3    in that a carbon dioxide pump may be used to separate at least a portion of the CO 2  from the anode exhaust stream. 
     Referring to  FIG.  4   , at least one carbon dioxide pump  600  may be located downstream of the water gas shift (WGS) reactor  405  and the condenser  406  in the anode exhaust stream from the hot boxes  100  of the fuel cell system  30 . The condenser  406  may be configured to condense water vapor to liquid water and to reduce the temperature of the anode exhaust stream such that the temperature and/or water content of the anode exhaust stream may be within the operating range(s) of the carbon dioxide pump  600 . Liquid water that is condensed from the anode exhaust stream may be removed via water exhaust conduit  407 . Anode exhaust conduit  308 L may provide the partially dehydrated anode exhaust stream from the condenser  406  to an inlet of the at least one carbon dioxide pump  600 . 
     The at least one carbon dioxide pump  600  may include an electrochemical carbon dioxide pump or pumps. The at least one electrochemical carbon dioxide pump  600  may be configured to pump CO 2  from the lower-pressure anode exhaust stream to a higher-pressure, nearly pure CO 2  product which may also contain water. In some embodiments, the at least one electrochemical carbon dioxide pump may include a scrubber and a separator (i.e., concentrator) that electrochemically pumps carbon dioxide through a polymer membrane upon application of a current or voltage across the membrane. In various embodiments, the at least one electrochemical carbon dioxide pump  600  may include a high-pressure carbon dioxide separation and compression system available from Skyre, Inc. under the name “CO2RENEW™” and/or described in U.S. Patent Application Publication No. 2020/0222852. The at least one carbon dioxide pump  600  may include multiple pumps (e.g., plural separation membrane stacks) connected in series and/or in parallel to enable a higher overall recovery fraction of CO 2  and/or a higher throughput. 
     In one embodiment, the at least one carbon dioxide pump  600  may recover at least 70%, such as 70-90% or more, of the CO 2  present in the dehydrated anode exhaust stream. In some embodiments, the at least one carbon dioxide pump  600  may pressurize the separated CO 2  product to a pressure between 1 psig and 5,000 psig, such as 1-5 psig, 5-150 psig, or 150-5,000 psig. In some embodiments, the compressed CO 2  product produced by the at least one carbon dioxide pump  600  may be suitable for use, storage, or sequestration without additional mechanical compression. 
     In some embodiments, the compressed CO 2  product from the at least one carbon dioxide pump  600  may be provided to a carbon dioxide processing device  424  via conduit  602 . The carbon dioxide processing device  424  may remove any residual water from the compressed CO 2  product, such as by thermal swing adsorption (TSA) and/or pressure swing adsorption (PSA). Water that is removed from the compressed CO 2  product may optionally be removed via a water exhaust conduit  425  for optional purification and/or reuse. The compressed CO 2  product may optionally undergo further compression to pressurize the CO 2  product to a pressure that is suitable for storage, use and/or sequestration. In some embodiments, the compressed CO 2  product may be liquified or solidified into dry ice. Following processing by the carbon dioxide processing device  424 , the compressed CO 2  product, which may include purified or pure CO 2 , may be provided to one or more CO 2  storage containers  427  via conduit  426  for storage and/or sequestration of the CO 2 , or may be used for chemical processes, beverage carbonation, etc. 
     Referring again to  FIG.  4   , the unpumped effluent from the at least one carbon dioxide pump  600  may contain hydrogen, water (e.g., water vapor and/or liquid water), carbon dioxide that was not separated from the anode exhaust by the at least one carbon dioxide pump  600 , as well as small amounts of carbon monoxide, nitrogen, and other impurities. In some embodiments, liquid water from the unpumped effluent may optionally be removed via a water exhaust conduit  601 . The remaining unpumped effluent from the at least one carbon dioxide pump  600  may be provided to conduit  603  for recycling to the fuel cell system  30 . 
     In various embodiments, the unpumped effluent from the at least one carbon dioxide pump  600  may include substantially all of the hydrogen and carbon monoxide from the anode exhaust stream. The concentrations of hydrogen and carbon monoxide within the unpumped effluent stream will generally be greater than their concentrations within the anode exhaust stream since most of the carbon dioxide and some of the water from the anode exhaust stream is removed by the at least one carbon dioxide pump  600 . This may make the effluent stream in conduit  603  advantageous for use in the fuel cell system  30 , including as a fuel source or supplemental fuel for the stacks  102  and/or the ATOs  130 . In various embodiments, at least one blower  604  may be in fluid communication with conduit  603 . The at least one blower  604  may include any suitable fluid (e.g., gas) blower, pump, compressor, or the like. The at least one blower  604  may compress the effluent stream to a pressure that is suitable for use in the fuel cell system  10 . In some embodiments, a plurality of blowers  604  may be utilize to compress portions of the effluent stream to different pressures for different uses in the fuel cell system  10 . For example, a first blower  604  in fluid communication with anode recycle conduit(s)  412 C may be used to increase the pressure of the effluent stream that is fed to the anode recycle loops of the hot boxes  100  by between 1 psi and 2 psi. At least a portion of the effluent that is provided to the hot boxes  100  may also be provided to the ATOs  130  of the hot boxes  100  for thermal management and/or to remove nitrogen from the ATOs  130 . A proportional solenoid valve may be used to control the portion of the effluent that is fed to the ATOs  130  of the respective hot boxes  100 . An additional blower  604  in fluid communication with anode recycle conduit  412 B may be used to increase the pressure of the effluent stream that is fed to the fuel inlet stream of the fuel cell system  30  by between 10 psi and 15 psi. 
     In the fuel cell system  30  shown in  FIG.  4   , since nearly all of the fuel may be recycled, either as a separated carbon dioxide product and/or as recycled fuel for the fuel cell system  30 , the per pass fuel utilization of the fuel cell system  30  may be lowered. Further, since any residual CO 2  in the effluent stream from the at least one carbon dioxide pump  600  is recycled back through the fuel cell system  30  and eventually to the anode exhaust stream from the hot boxes  100 , the at least one carbon dioxide pump  600  does not need to have an extremely high CO 2  recovery rate. In some embodiments, the per pass CO 2  recovery rate of the at least one carbon dioxide pump  600  may be between 70-90%. This may enable nearly 100% overall CO 2  recovery for the fuel cell system  30 , minus a small amount of CO 2  that may be recycled to and/or generated by the ATOs  130  of the hot boxes  100 . 
     Depending on the CO tolerance of the at least one carbon dioxide pump  600 , in some embodiments, the WGS reactor  405  and the anode exhaust conditioning unit  404  may be eliminated from the fuel cell system  30  of  FIG.  4   . Accordingly, the anode exhaust from the manifold  104  may be fed to the condenser  406  which may be configured to condition the anode exhaust stream such that the temperature and/or water content of the anode exhaust stream may be within the operating range(s) of the at least one carbon dioxide pump  600 . In such a case, the anode exhaust stream that enters the at least one carbon dioxide pump  600 , as well as the effluent stream from the at least one carbon dioxide pump  600 , may have relatively higher concentrations of H 2  and CO. 
       FIG.  5    schematically illustrates a fuel cell system  40  according to another embodiment of the present disclosure. The fuel cell system  40  of  FIG.  5    may be similar to fuel cell system  30  described above with reference to  FIG.  4   . Thus, repeated discussion of like components is omitted for brevity. The fuel cell system  40  of  FIG.  5    may differ from the fuel cell system  30  of  FIG.  4    by the addition of at least one hydrogen pump  408  upstream of the at least one carbon dioxide pump  600 . In various embodiments, the anode exhaust stream may be provided from condenser  406  to the at least one hydrogen pump  408  via anode exhaust conduit  308 L. The at least one hydrogen pump  408  may produce a compressed hydrogen product as described above, which may be provided to conduit  410 . The compressed hydrogen product from the at least one hydrogen pump  408  may be recycled to the fuel cell system  30  and/or provided to one or more hydrogen storage containers  414  for storage and potential commercial sale. In the embodiment shown in  FIG.  5   , a splitter  413  may be used to provide a portion of the compressed hydrogen product to one or more hydrogen storage containers  414  via hydrogen storage conduit  413 , while a remaining portion of the compressed hydrogen product may be recycled for use in the fuel cell system via conduit  412 A. 
     The unpumped effluent from the at least one hydrogen pump  408  may contain primarily water (e.g., water vapor and/or liquid water) and carbon dioxide, along with smaller amounts of hydrogen, carbon monoxide, nitrogen, and other impurities. Liquid water from the unpumped effluent may optionally be removed via water exhaust conduit  417 . The remaining effluent stream may be provided to the at least one carbon dioxide pump  600  via conduit  308 M. The at least one carbon dioxide pump  600  may separate the majority (e.g., 70% or more) of the CO 2  from the effluent stream and provide a compressed CO 2  product as described above with reference to  FIG.  4   . The compressed CO 2  product may optionally be provided to CO 2  processing device  424  via conduit  602 . 
     The unpumped effluent from the at least one carbon dioxide pump  600  may include water (e.g., water vapor and/or liquid water) and carbon dioxide that was not separated by the at least one carbon dioxide pump  600 , as well as small amounts of hydrogen, carbon monoxide, nitrogen, and other impurities. Liquid water from the unpumped effluent may optionally be removed via water exhaust conduit  601 . The remaining effluent may be provided to conduit  603  to be recycled for use in the fuel cell system  40  as described above. 
     An advantage of providing at least one hydrogen pump  408  upstream of the at least one carbon dioxide pump  600  is that the at least one hydrogen pump  408  may reduce the gas flow rate of the process stream before it is fed to the at least one carbon dioxide pump  600 . In addition, by removing hydrogen using the at least one hydrogen pump  408 , the concentration of CO 2  in the process stream that is fed to the at least one carbon dioxide pump  600  may be increased. The system  40  of  FIG.  5    may also produce a pure or purified hydrogen product, which may be stored for later use and/or sold. 
       FIG.  6    schematically illustrates a fuel cell system  50  according to another embodiment of the present disclosure. The fuel cell system  50  of  FIG.  5    may be similar to fuel cell system  10  described above with reference to  FIG.  2   . Thus, repeated discussion of like components is omitted for brevity. The fuel cell system  50  of  FIG.  3    may differ from the fuel cell system  10  of  FIG.  2    by the addition of at least one carbon dioxide pump  600  upstream of the at least one hydrogen pump  408 . In various embodiments, the anode exhaust stream may be provided from condenser  406  to the at least one carbon dioxide pump  600  via anode exhaust conduit  308 L. The at least one carbon dioxide pump  600  may separate the majority (e.g., 70% or more) of the CO 2  from the anode exhaust stream and provide a compressed CO 2  product as described above with reference to  FIG.  4   . The compressed CO 2  product may optionally be provided to CO 2  processing device  424  via conduit  602 . 
     The unpumped effluent from the at least one carbon dioxide pump  600  may include a hydrogen-rich process stream including water (e.g., water vapor and/or liquid water), hydrogen, and carbon dioxide that was not separated by the at least one carbon dioxide pump  600 , as well as small amounts of carbon monoxide, nitrogen, and other impurities. Liquid water from the unpumped effluent may optionally be removed via water exhaust conduit  601 . The remaining effluent may be provided to the at least one hydrogen pump  408  via conduit  604 . 
     The at least one hydrogen pump  408  may produce a compressed hydrogen product as described above, which may be provided to conduit  410 . The compressed hydrogen product from the at least one hydrogen pump  408  may be recycled to the fuel cell system  30  and/or provided to one or more hydrogen storage containers  414  for storage and potential commercial sale. In the embodiment shown in  FIG.  6   , a splitter  411  may be used to provide a portion of the compressed hydrogen product to one or more hydrogen storage containers  414  via hydrogen storage conduit  413 , while a remaining portion of the compressed hydrogen product may be recycled for use in the fuel cell system via conduit  412 A. 
     The unpumped gaseous effluent from the at least one hydrogen pump  408  may be provided from the at least one hydrogen pump  408  to effluent conduit  418 , and may optionally be fed to a blower  419  and an oxidation reactor  421  configured to reduce or eliminate residual H 2  and CO from the effluent prior as described above with reference to  FIG.  2   . The remaining effluent, which may include primarily water and CO 2 , may be provided to CO 2  processing device  424  via conduit  606  for recovery, storage and/or use of the remaining CO 2  as described above. 
     The preceding description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of the disclosure. Thus, the present disclosure is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.