Patent Abstract:
A fuel cell device for providing electrical energy, the fuel cell device comprising a first storage tank for storing a hydrogen-based fuel, a second storage tank for storing an oxidant, a fuel cell portion having an electron input, an electrolysis portion having an electron output, and an electrolyte recovery unit. A method for generating electrical energy using a fuel cell device having a fuel cell portion and an electrolysis portion is also provided.

Full Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/231,804, filed on Sep. 11, 2000, entitled ELECTROLYSIS FUEL CELL ENERGY PLANT 
     
    
     
       TECHNICAL FIELD  
         [0002]    The present invention relates generally to a fuel cell device for providing energy. More specifically, the present invention relates to a fuel cell device that provides electrical energy and incorporates an electrolysis portion to at least partially recycle fuel cell reactants from fuel cell waste water and enables electrolyte recovery.  
         BACKGROUND OF THE INVENTION  
         [0003]    Electrical power systems are nonlinear systems that are large and quite complex. Their limited available control and generally sluggish dynamic response complicate these power systems. Moreover, the magnitude of these power systems does not easily provide for a rapid control response to disturbances. Restoring a system to its pre-disturbance level can take hours. Furthermore, as a result of the increasing social and environmental costs of installing transmission lines, transmission systems will be driven closer to their limits. The difficulty in controlling these power systems will only increase with their heavy loads.  
           [0004]    Power systems in the United States are already being pushed more heavily now than ever before. Recent events on the West Coast demonstrate potential nationwide problems. The United States&#39; power transmission infrastructure is encountering a variety of new demands that it was never designed to meet. At the same time, major componentry of the systems are nearing the end of their design lifetime. A major investment in rebuilding the power transmission infrastructure will be required, as well as the development of new technologies, in order to get the maximum utilization out of the existing plants at a lower cost.  
           [0005]    Power flow from one point to another within an interconnected system obeys Kirchhoff&#39;s Laws. Current is divided between parallel pathways leading to the identical destination. Unfortunately, pathways running parallel to the desired paths may be owned or operated by separate entities, or may already be loaded to capacity. Control of the loop flows is presently accomplished through the use of phase shifting transformers and series capacitors. These devices lack the ability to be rapidly adjusted, a significant detriment in a field where flows of power may quickly be altered. The tremendous increase in the use of retail wheeling and contracted power transfers requires a substantially increased ability to determine the pathways taken by power flows.  
           [0006]    Fuel cells have been known for over 150 years, and are currently positioned to make substantial contributions in the field of stationary power generation. Ludwig Mond and Charles Langer, who attempted to build the first practical fuel cell device using air and industrial coal gas, coined the term “fuel cell.” Early attempts to build fuel cells for converting coal or carbon directly into electricity failed as a result of a dearth of knowledge regarding materials and the kinetics of electrodes.  
           [0007]    The first successful fuel cell devices resulted from inventions that improved on the previously employed expensive platinum catalysts with a hydrogen-oxygen cell utilizing a less corrosive alkaline electrolyte and inexpensive nickel electrodes. However, the technical challenges were discouraging and it was not until the 1950&#39;s that fuel cell systems showed promise as energy sources with significant output. At that time, the National Aeronautics and Space Administration (NASA) turned to fuel cells for compact electricity generators to provide onboard power for manned space missions.  
           [0008]    Generally, fuel cell devices produce electricity by combining hydrogen ions that are derived from a hydrogen-containing fuel with oxygen atoms. Unlike batteries, which provide the fuel and oxidizer internally and must be recharged periodically, fuel cells utilize a supply of ingredients from an outside source and produce power so long as the fuel supply is maintained. By continuously changing the chemical energy of a fuel source, such as hydrogen gas, and oxidant, such as oxygen or air, to electrical energy, a typical fuel cell device generates electricity. This process does not consume the fuel to produce heat; hence the thermodynamic limits on efficiency are much higher than the traditional power generation processes. A fuel cell generally consists of two catalytic electrodes separated by an ion-conducting membrane. The hydrogen fuel is ionized on one electrode, and the subsequent hydrogen ions diffuse across the membrane to interact with the oxygen ions on the surface of the other electrode. If current flow is prohibited from one electrode to the other, a potential gradient develops, stopping the diffusion of the hydrogen ions. Permitting current to flow from one electrode to the other through an external load creates power.  
           [0009]    The membrane that separates the electrodes ideally provides for the diffusion of ions from one electrode to the other, and additionally keeps the fuel and oxidant gases apart. The membrane prevents the flow of electrons, as well as the diffusion of the fuel or oxidant gases, to reduce the possibility of explosions and other unintended consequences. If electrons pass through the membrane, the device is shorted out, thus eliminating or reducing the useful power formed by the fuel cell.  
           [0010]    A fuel cell having catalytic electrodes in close contact with the membrane material reduces the contact resistance that occurs when the ions move between the catalytic electrode and the membrane. The aforementioned close contact can be accomplished by incorporating the membrane material into the electrodes.  
           [0011]    The fuel cell facilitates chemical reactions that produce either hydrogen- or oxygen-bearing ions at one of the electrodes of the cell. The ions then pass through an electrolyte, such as phosphoric acid or carbonate, and react with oxygen atoms. This interaction results in an electric current at both electrodes, and produces heat and water vapor as waste products. The strength of the electric current is proportional to the surface area of the electrodes. The voltage of a fuel cell is limited electrochemically to approximately 1.23 volts per electrode pair. Thus, fuel cells then can be stacked until the desired power level is reached.  
           [0012]    One of the major challenges in developing practical applications for fuel cells has been to improve the economics through the use of low-cost components with acceptable component life and performance. As a result, fuel cells are distinguishable by the type of electrolyte used. In the realm of stationary power generation, the conventional types of fuel cells use phosphoric acid, carbonate, or solid oxide as electrolytes. Differentiation between fuel cell approaches is found in the type of electrolyte used.  
           [0013]    The phosphoric acid approach is the most established of the approaches. Platinum is required as a catalyst for the electrodes. Conversion of the natural gas, known as reforming, used as fuel to a hydrogen-rich gas the system requires occurs outside the fuel cell stacks. The system complexity of this approach yields capital costs that are higher and efficiencies that are lower than those for the two other approaches.  
           [0014]    The carbonate approach operates at higher temperatures, at or slightly above ambient pressure, and uses less expensive, nickel-based electrodes than the phosphoric acid approach. Reforming can occur inside the fuel cell stacks. The major difficulties with carbonate technology include (1) the complexity of working with a liquid electrolyte rather than a solid and (2) the carbonate ions from the electrolyte are used up in the reactions at the anode, making it necessary to compensate by injecting carbon dioxide at the cathode.  
           [0015]    The solid oxide approach is the least developed of these approaches. It uses a coated zirconia ceramic as the electrolyte. The electrochemical conversion process occurs at extremely high temperatures, sustaining internal reforming. The fuel cells may be either flat plates or tubular in shape. Unresolved manufacturing difficulties with all-ceramic construction in mass producing these fuel cells hampers this approach.  
           [0016]    Additionally, a proton exchange membrane, also known as a polymer electrolyte membrane, fuel cell approach has been postulated for submegawatt stationary power plant applications. The proton exchange membrane allows protons to flow through, but prohibits the passage of electrons. As a result, while the electrons flow through an external circuit, the hydrogen ions flow directly through the proton exchange membrane to the cathode, where they combine with oxygen molecules and the electrons to form water. A fuel cell under this approach operates at 175° F., uses a platinum catalyst, and is susceptible to poisoning by carbon monoxide and other impurities.  
           [0017]    It is thus an object of the present invention to provide a fuel cell energy plant that has improved efficiency through a combination of a fuel cell portion and an electrolysis portion. The fuel cell portion combines hydrogen and oxygen to produce electricity, forming water as a waste product that is then split by the electrolysis potion to form hydrogen and oxygen. The hydrogen and oxygen is sent back to the fuel cells for reuse.  
           [0018]    Therefore, a continuing need exists for a fuel cell energy plant that overcomes the efficiency problems existing in prior fuel cell systems, including but not limited to fuel usage, by coupling a fuel cell portion to an electrolysis portion.  
         SUMMARY OF THE INVENTION  
         [0019]    The present invention eliminates the above-mentioned needs by providing a fuel cell device for generating electrical energy through the combination of a hydrogen-based fuel with an oxidant in the presence of an electrical charge. The water subsequently produced as a waste product is at least partially recycled into hydrogen and oxygen, to be reused as fuel and oxidant, respectively. Thus, the present invention obtains a heightened overall efficiency that approaches one hundred percent recycling of the fuel and oxidant.  
           [0020]    In accordance with the present invention, there is provided a fuel cell device for providing electrical energy. The fuel cell device includes a first storage tank for storing a hydrogen-based fuel and a second storage tank for storing an oxidant. The fuel cell device further includes a fuel cell portion having an electron input from an external load. The electron input provides a pathway for electrons to pass through the fuel cell portion and into the electrolysis portion. The electrolysis portion has an electron output to provide a pathway for electrons to leave the fuel cell device. An electrolyte recovery unit is provided to redirect electrolyte overflow. The electrolyte overflow is redirected back into the electrolysis portion or into a third storage tank for future use.  
           [0021]    The present invention is further directed to a method for generating electrical energy using a fuel cell device having a fuel cell portion and an electrolysis portion. The method includes the storing of a hydrogen-based fuel in a first storage tank and storing an oxidant in a second storage tank. The hydrogen-based fuel, oxidant, and electrons are supplied to the fuel cell portion, resulting in the combination of the hydrogen-based fuel and oxidant. This combination generates electrical energy and waste water. The waste water is supplied to the electrolysis portion having an electrolyte and is split into hydrogen and oxygen. The hydrogen from the electrolysis portion is supplied to the first storage tank and the oxygen from the electrolysis portion is supplied to the second storage tank. The electrolysis portion provides flow of the electrolyte to an electrolyte recovery pump, the flow being redirected. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    [0022]FIG. 1 is an illustration of a flow block diagram of the process by which the fuel cell device of the present invention creates electrical power.  
         [0023]    [0023]FIG. 2 is an illustration of the front view of the fuel cell device of FIG. 1.  
         [0024]    [0024]FIG. 3 is an illustration of a stacked arrangement of a plurality of the fuel cell devices of FIG. 2.  
         [0025]    [0025]FIG. 4 is an illustration of the glass liquid separator of the fuel cell device of FIG. 3.  
         [0026]    [0026]FIG. 5 is an illustration of a flow block diagram of the process by which the electrons flow through the fuel cell device of FIG. 1. 
     
    
     DETAILED DESCRIPTION  
       [0027]    Referring now to FIGS. 1 and 2, a preferred embodiment of the present invention is illustrated as the fuel cell device  10 . The fuel cell device  10  has a glass casing  21  for electrical insulation. The fuel device  10  includes a first storage tank  11  for storing a hydrogen-based fuel, a second storage tank  12  for storing an oxidant, a fuel cell portion  20  having an electron input  26 , an electrolysis portion  30  having an electron output  33 , and an electrolyte recovery unit  40 .  
         [0028]    The first storage tank  11  is operatively engaged to the fuel cell portion  20  in a manner that allows for the hydrogen-based fuel to flow from the first storage tank  11  into a hydrogen storage section  21 A of the fuel cell portion  20 . Further, the first storage tank  11  has a pressure valve  13  to regulate fuel pressure within the first storage tank  11  and a flow control valve  14  to regulate fuel flow from the first storage tank  11  to the hydrogen storage section  21 A of fuel cell portion  20 . The hydrogen-based fuel can consist of hydrogen gas, hydrocarbons, hydrazine, and alcohol.  
         [0029]    Second storage tank  12  is also operatively engaged in a manner that allows for the oxidant to flow from the first storage tank  11  into an oxidant storage section  21 B of the fuel cell portion  20 . Moreover, the second storage tank  12  also includes a pressure valve  13  to regulate oxidant pressure within the second storage tank  12  and a flow control valve  14  to regulate oxidant flow from the second storage tank  12  to the oxidant storage section  21 B of fuel cell portion  20 . The oxidant can consist of oxygen gas and air.  
         [0030]    In the preferred embodiment, the fuel cell portion  20  further includes a pair of electrodes  22  and  23 , one electrode being a cathode and the other being and anode. Displaced between the electrodes  22  and  23 , and separating the hydrogen-based fuel storage section  21 A from the oxidant storage section  21 B, is an ion conducting membrane  24  that allows hydrogen ions from the hydrogen-based fuel to diffuse across and interact with oxygen ions from said oxidant. A glass separator  28  is used to prevent undesired contact between the hydrogen-based fuel and the oxidant, further functioning to separate the hydrogen-based fuel storage section  21 A from the oxidant storage section  21 B.  
         [0031]    As illustrated in FIGS. 1, 3, and  5  of the preferred embodiment of the present invention, the external load  60  supplies electrons to the fuel cell portion  20 . The electrons are supplied to the fuel cell portion  20  via the conductor wire  25  from the external load  60  through the electron input  26 . The conductor wire  25  then supplies the electrons to the oxidant storage section  21 B. In the preferred embodiment, the electrons pass from the oxidant storage section  21 B to the hydrogen-based fuel storage section  21 A by traversing the ion conducting membrane  24 .  
         [0032]    In accordance with the preferred embodiment, the electrons subsequently exit the hydrogen-based fuel storage section  21 A through the conductor wire  25 . The conductor wire  25  provides a pathway for the electrons to enter the electrolysis portion  30 . The electrons then electrically engage the plate electrodes  31  and eventually exit the electrolysis portion  30  along the conductor wire  25  of the electron output  33 .  
         [0033]    In further accord with the preferred embodiment, the conductor wire ultimately routes the electrons back to the external load  60 . Electrons are then recycled into the system through electron input  26  via a conductor wire  25 . Preferably, the conductor wire  25  is made of platinum. In addition, the fuel cell device  10  combines said hydrogen-based fuel with the oxidant in the presence of electrons to produce electrical power and waste water. Furthermore, the fuel cell portion  20  is integrally connected to the electrolysis portion  30  so as to reduce electrical resistance.  
         [0034]    As shown in FIGS. 1 through 3, a glass liquid separator  27  at the bottom of the fuel cell portion  20  functions to provide waste water to the electrolysis portion through a series of channels  29 , as well as to divide the fuel cell portion  20  from the electrolysis portion  30 . FIG. 4 illustrates the channels  29  that are formed through the glass liquid separator  27 . The channels  29  are porous to water and not to the electrolyte  32  of the electrolysis portion  30 . Thus, waste water formed in the fuel cell portion  20  is transported into the electrolysis portion  30  through the channels  29  of the glass liquid separator  27  via diffusion.  
         [0035]    Referring back to FIGS. 1 and 2, the electrolysis portion  30  itself further contains at least one plate electrode  31  for assisting in the electrolysis reaction. In addition, the electrolysis portion  30  contains an electrolyte  32  to further promote the electrolysis reaction. The electrolyte  32  is typically an acid, and preferably sulfuric acid. Moreover, the electrolysis portion  30  also includes an open glass separator  36  to allow the electrolyte  32  to flow between plate electrodes  31 . As a result, the electrolysis portion  30  functions to split the waste water into hydrogen and oxygen. After splitting the waste water into hydrogen and water, the electrolysis portion  30  then recycles hydrogen to the first storage tank  11  and recycles oxygen to the second storage tank  12 . Electrons are removed through an electron output  33  via the conductor wire  25  to the external load  60 .  
         [0036]    As shown in FIG. 1, the electrolysis portion  30  is operatively engaged to the electrolyte recovery unit  40 . The electrolyte recovery unit  40  includes an overflow intake  34  to accept excess electrolyte  32 . Furthermore, the electrolyte recovery unit  40  pumps the overflow electrolyte  32  via a return  35  to provide electrolyte flow back into the electrolysis portion  30 . The return  35  of the electrolyte recovery unit  40  can also provide electrolyte flow to a third storage tank to be stored for future use.  
         [0037]    As illustrated in FIGS. 1 through 3, the fuel cell device  20  further includes a heat exchanger  50  to control the temperature of the fuel cell  20 . Cold water enters the heat exchanger  50  through water inlet  51 , and the subsequently warmed water exits the heat exchanger  50  through water outlet  52 .  
         [0038]    Additionally, as illustrated in FIG. 3, the fuel cell device  20  may be stacked with other fuel cell devices to form a plurality of fuel cell devices to obtain a desired power output.  
         [0039]    While the preferred embodiment of the present invention has been described in detail above, those skilled in the art will readily appreciate that numerous modifications are to the exemplary embodiment is possible without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims.

Technology Classification (CPC): 7