Patent Document

CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims priority to U.S. application Ser. No. 12/421,782, filed Apr. 10, 2009, entitled “Membrane for Electrochemical Apparatus”, now U.S. Pat. No. 8,465,629, which claims priority to U.S. Provisional Application No. 61/044,336, filed Apr. 11, 2008, entitled “Hydrogen Generation Process”, now expired, which applications are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This description relates to electrochemical systems, particularly hydrogen generation systems and, more particularly, to the electrolysis of water to produce hydrogen. 
     BACKGROUND 
     Hydrogen can provide clean energy for powering automobiles as well as for cooking, space heating, heating hot water, and supplying power to absorption air conditioning and refrigeration units. In addition, unlike conventional electricity, it may be stored for later use. As currently envisioned, widespread use of hydrogen will require a significant infrastructure for the efficient distribution and use of this fuel. Costs of hydrogen generation may also be a factor in its widespread use. 
     Hydrogen may be produced by the electrolysis of water, a readily available and inexpensive feedstock, by passing an electric current through the water. A source of direct current electricity is connected to an anode and a cathode placed in contact with the water and hydrogen is generated at the cathode and oxygen is generated at the anode. A membrane is interposed between the anode and the cathode and hydrogen ions move across the membrane, where they combine with electrons to form hydrogen gas. The membrane must be durable enough to withstand the caustic environment of the electrolysis process as well as the physical stress of the sometimes violent production of hydrogen and oxygen gas. Waste heat is also generated in the process, which, if recovered, may result in an increase in the overall efficiency of the electrolytic process. 
     There are many sources of the electric energy needed to generate hydrogen by the process of electrolysis. Traditional sources include burning fossil fuels such as coal, petroleum derivatives, and natural gas and nuclear plants and non-traditional sources such as wind power and solar panels may also be used. The flexibility to utilize electricity generated by a variety of sources can provide greater reliability of hydrogen generation. Utilizing electricity to generate hydrogen can also provide a convenient storage medium which may be used to dampen time-dependent fluctuations in power supply and energy demand. 
     SUMMARY 
     Electrochemical apparatus and processes can utilize electricity to induce a chemical reaction, such as the separation of water into its component element hydrogen and oxygen in an electrolyzer, or to provide electrical energy by combining hydrogen and oxygen to produce water, as in a fuel cell. 
     A comprehensive electrolytic hydrogen generation process may effectively utilize clean alternative power, make hydrogen fuel available without relying upon a complex and expensive hydrogen distribution infrastructure, and eliminate complex and expensive waste disposal problems. 
     Included is a ripstop nylon fabric membrane for an electrochemical apparatus and process that is both durable and low-cost. Optionally, the ripstop nylon membrane is combined with a plastisol-based gasket in a membrane assembly. Also included are light-weight, low-cost high-density polyethylene (HDPE) components, which components can be formed to frame both single electrodes and single membranes in one-piece modules. Multiple electrode modules and membrane modules can be combined to produce a multi-cell electrolyzer system. Also included are small inter-electrode gaps and high electrode-water contact areas to help effect high-efficiency electrolyzer operation. Included, too, are effective and low-cost safety and process control features that help reduce or minimize the dangers of the electrolytic generation of hydrogen. 
     An electrolyzer can flexibly utilize electrical power from a variety of sources. Wind of any speed sufficient to turn a wind turbine may be utilized. Either wind or solar power can be converted to hydrogen and stored during off-peak times or when such generated electrical power is more than required to meet demand. A rectifier may be provided to convert conventional AC power to provide DC to the electrolyzer if desired. Batteries may be charged by either wind or solar power and later used to power the electrolyzer or to smooth out changes in source. 
     Waste heat may be captured and put to other uses. For example, by enclosing the electrolyzer, water or other heat transfer medium may be circulated to provide heat for a residence or office. By enclosing the hydrogen and oxygen collection towers, air or other suitable heat transfer media may be circulated to collect additional waste heat. Further efficiencies may be obtained by circulating water or other suitable heat transfer medium through heat-transfer coils included within the towers. 
     In one embodiment, an apparatus comprises a first compression plate; a first insulator plate next to the first compression plate; a first electrode next to the first insulator plate; a first end frame next to the first electrode, the first end frame having an aperture, a liquid inlet, a channel formed between the aperture and the liquid inlet, a gas outlet, and a channel formed between the aperture and the gas outlet; the apparatus further comprising at least one membrane-electrode assembly, the at least one membrane-electrode assembly next to the first end frame and comprising a membrane assembly, the membrane assembly comprising a ripstop nylon membrane and a gasket affixed to a border of the membrane; the at least one membrane-electrode assembly further comprising a first interior frame, the first interior frame comprising an aperture, at least one liquid inlet, a channel formed between the aperture and the liquid inlet, a gas outlet, and a channel formed between the aperture and the gas outlet; the at least one membrane-electrode assembly further comprising an interior electrode and a second interior frame, the second interior frame comprising an aperture, at least one liquid inlet, a channel formed between the aperture and the liquid inlet, a gas outlet, and a channel formed between the aperture and the gas outlet; the apparatus further comprising a further membrane assembly, the further membrane assembly next to the membrane-electrode assembly and comprising a ripstop nylon membrane and a gasket affixed to a border of the membrane; the apparatus further comprising a second end frame, the second next to the further membrane assembly and comprising an aperture, a liquid inlet, a channel formed between the aperture and the liquid inlet, a gas outlet, and a channel formed between the aperture and the gas outlet; the apparatus further comprising a further electrode, the further electrode next to the second end frame; a second insulator plate, the second insulator plate next to the further electrode; and a second compression plate, the second compression plate next to the second insulator plate. The further electrode, the second insulator plate, and the second compression plate may each further include a liquid inlet and a gas outlet. 
     As will be appreciated by those skilled in the relevant art, these elements will be interleaved with one another to create an electrochemical apparatus, and especially an electrolyzer. 
     In a further embodiment, a membrane for an electrolyzer comprises a synthetic fabric. In a further embodiment, the synthetic fabric comprises nylon. In a further embodiment, the nylon comprises ripstop nylon. 
     In a further embodiment, a method comprises impressing a DC electric current across a ripstop nylon membrane. 
     In a further embodiment, a method comprises applying a plastisol border to a ripstop nylon membrane. 
     In a further embodiment, a method comprises (a) placing a first side of a first insulator plate against a second side of a first compression plate; (b) placing a first side of a first electrode against a second side of the first insulator plate; (c) placing a first side of a first end frame against a second side of the first electrode, the first end frame comprising: a second side; a liquid inlet forming a hole between the first side and the second side; a channel formed on the first side between the aperture and the liquid inlet; a gas outlet forming a hole between the first side and the second side; and a channel formed on the first side between the aperture and the gas outlet; (d) placing a first membrane assembly side of at least one membrane-electrode assembly against the second side of the first end frame, the at least one membrane-electrode assembly comprising: a membrane assembly, the membrane assembly comprising: a ripstop nylon membrane; and a gasket affixed to a border of at least one side of the membrane; a first frame, the first frame defining an aperture, and comprising: a first side, the first side facing and abutting a second side of the membrane assembly; a second side; a liquid inlet forming a hole between the first side and the second side; a channel formed on the second side between the aperture and the liquid inlet; a gas outlet forming a hole between the first side and the second side; and a channel formed on the second side between the aperture and the gas outlet; an interior electrode, a first side of the interior electrode facing and abutting the second side of the first interior frame; and a second frame, the second frame defining an aperture, and comprising: a first side, the first side facing and abutting a second side of the interior electrode; a second side; a liquid inlet forming a hole between the first side and the second side; a channel formed on the first side between the aperture and the liquid inlet; a gas outlet forming a hole between the first side and the second side; and a channel formed on the first side between the aperture and the gas outlet; (e) placing a first side of a further membrane assembly against the second side of the second frame of the membrane-electrode assembly; (f) placing a first side of a second end frame against a second side of the further membrane assembly; (g) placing a first side of a further electrode against a second side of the second end frame; (h) placing the first side of a second insulator plate against a second side of the further electrode; and (i) placing a first side of a second compression plate against a second side of the second insulator plate. The further electrode, the second insulator plate, and the second compression plate may each further include a liquid inlet and a gas outlet. 
     In a further embodiment, a process comprises: (a) introducing a portion of an aqueous solution into a cathodic chamber, the cathodic chamber defined by a cathode and a membrane, the membrane comprising ripstop nylon; (b) introducing a portion of the aqueous solution into an anodic chamber, the anodic chamber defined by an anode and the membrane, the anodic chamber in fluid communication with the cathodic chamber, the anode positioned such that the membrane is interposed between the cathode and the anode; (c) applying a DC electrical potential between the cathode and the anode, whereby the application of the DC electrical potential effects a DC potential across the membrane; (d) withdrawing a first electrolytic decomposition product of water from the cathodic chamber; and (e) withdrawing a second electrolytic decomposition product of water from the anodic chamber. 
     In a further embodiment, the cathodic chamber (immediately above) is further defined by the aperture of a first frame, the first frame interposed between the cathode and the membrane (immediately above); and the anodic chamber (immediately above) is further defined by the aperture of a second frame, the second frame interposed between the anode and the membrane; and wherein: step (d) (immediately above) further comprises the step of: (A) withdrawing the first electrolytic decomposition of water product (immediately above) from the cathodic chamber through a first product channel and a first product outlet, the first product outlet in fluid communication with the cathodic chamber via the first product channel; and step (e) (immediately above) further comprises the step of: (B) withdrawing the second electrolytic decomposition of water product (immediately above) from the anodic chamber through a second product channel and a second product outlet, the second product outlet in fluid communication with the anodic chamber via the second product channel. 
     In a further embodiment, a process comprises: (a) introducing a portion of an aqueous solution into a plurality of cathodic chambers, each cathodic chamber defined by a membrane, the membrane comprising ripstop nylon, and an electrode; (b) introducing at least a portion of the aqueous solution into a plurality of anodic chambers, each anodic chamber at least partially defined by a membrane and an electrode, wherein cathodic chambers alternate with anodic chambers; (c) effecting a DC potential across each membrane; (d) withdrawing at least one electrolytic decomposition product of water from at least one of the plurality of cathodic chambers; and (e) withdrawing at least one electrolytic decomposition product of water from at least one of the plurality of anodic chambers. 
     In a further embodiment, a process comprises: (a) introducing a portion of an aqueous solution into a cathodic chamber, the cathodic chamber defined by a cathode and a first membrane; (b) introducing a portion of the aqueous solution into an anodic chamber, the anodic chamber defined by an anode and a second membrane; (c) introducing a portion of the aqueous solution into a plurality of further cathodic chambers, the plurality of further cathodic chambers at least partially defined by a bi-polar electrode and a further membrane; (d) introducing a portion of the aqueous solution into a plurality of further anodic chambers, the plurality of further anodic chambers at least partially defined by a bi-polar electrode and a further membrane; (e) applying a DC electrical potential between the cathode and the anode, whereby the application of the DC electrical potential effects a DC potential across each membrane; (f) withdrawing hydrogen gas from at least one cathodic chamber; and (g) withdrawing oxygen gas from at least one anodic chamber, wherein at least one membrane comprises ripstop nylon. 
     In a further embodiment, a process comprises: (a) providing an apparatus, the apparatus comprising: (i) a cathode; (ii) a first end frame, the first end frame defining an aperture, the first end frame comprising: (A) a first side, the first side facing a second side of the cathode; (B) a second side; (C) a liquid inlet forming a hole between the first side and the second side; (D) a channel formed on the first side between the aperture and the liquid inlet; (E) a gas outlet forming a hole between the first side and the second side; and (F) a channel formed on the first side between the aperture and the gas outlet; (iii) at least one membrane-electrode assembly, a membrane side of the membrane-electrode assembly facing the second side of the first end frame, the at least one membrane-electrode assembly comprising: (A) a membrane, the membrane comprising ripstop nylon, the cathode, the first end frame, and the membrane defining a cathodic chamber; (B) a first interior frame, the first interior frame defining an aperture, and comprising: (a′) a first side, the first side facing a second side of the membrane; (b′) a second side; (c′) a liquid inlet forming a hole between the first side and the second side; (d′) a channel formed on the second side between the aperture and the liquid inlet; (e′) a gas outlet forming a hole between the first side and the second side; and (f′) a channel formed on the second side between the aperture and the gas outlet; (C) an interior electrode, the first side of the interior electrode facing the second side of the first interior frame, the membrane, the first interior frame, and the interior electrode defining an anodic chamber; (D) a second interior frame, the second interior frame defining an aperture, and comprising: (a′) a first side, the first side facing a second side of the electrode; (b′) a second side; (c′) a liquid inlet forming a hole between the first side and the second side; (e′) a channel formed on the first side between the aperture and the liquid inlet; (f′) a gas outlet forming a hole between the first side and the second side; and (g′) a channel formed on the first side between the aperture and the gas outlet; (iv) a further membrane, the further membrane comprising ripstop nylon, a first side of the further membrane facing the second side of a second interior frame, the interior electrode, the second interior frame, and the further membrane defining a cathodic chamber; (v) a second end frame, the second end frame defining an aperture, and comprising: (A) a first side, the first side facing a second side of the further membrane; (B) a second side; (C) a liquid inlet forming a hole between the first side and the second side; (D) a channel formed on the second side between the aperture and the liquid inlet; (E) a gas outlet forming a hole between the first side and the second side; and (F) a channel formed on the second side between the aperture and the gas outlet; (vi) an anode, a first side of the anode facing the second side of the second end frame, the further membrane, the second end frame, and the further electrode defining an anodic chamber; (b) introducing an aqueous solution into each cathodic chamber via a liquid inlet hole and a liquid inlet channel; (c) introducing the aqueous solution into each anodic chamber via a liquid inlet hole and ail quid inlet channel; (d) applying a DC electrical potential between the cathode and the anode, whereby the application of the DC electrical potential effects a DC potential across each membrane; (e) withdrawing hydrogen from each cathodic chamber via a gas outlet hole and a gas outlet channel; and (f) withdrawing oxygen from each anodic chamber via a gas outlet hole and a gas outlet channel. 
     The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The accompanying drawings, which are incorporated in, and constitute a part of, this specification, illustrate several embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1  is a block diagram illustrating a hydrogen system. 
         FIG. 2  is a partial cutaway view illustrating an electrolyzer and associated collection towers along with enclosures. 
         FIGS. 3 and 4  combine to give an exploded view illustrating components of an electrolyzer. 
         FIG. 5  illustrates the detail of a channel. 
         FIG. 6  illustrates the detail of a membrane fabric. 
         FIG. 7  is a process diagram illustrating an electrolyzer and associated ancillary equipment and controls. 
         FIGS. 8 and 9  are circuit diagrams illustrating monitoring and control circuits for an electrolyzer and associated ancillary equipment. 
         FIG. 10  is a circuit diagram illustrating an oxygen sensor and associated control circuit. 
         FIG. 11  is an exploded view of a framed electrode. 
         FIG. 12  is an exploded view of a framed membrane. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a hydrogen system  10  includes an electrolyzer process  100  (shown also in  FIGS. 2 and 7 ) adapted to produce hydrogen  32  from water  34  using electricity  28 . The electrolyzer process  100  converts water  34  into its component parts of hydrogen  32  and oxygen  30 . An electrolyte  36  is combined with the water  34  in a feedwater tank  38  and introduced into the electrolyzer process  100  as feedwater  40 . Typically, the electrolyte  36  is sodium hydroxide (NaOH) or potassium hydroxide (KOH), but cations such as, but not limited to, lithium (Li + ), rubidium (Rb + ), potassium (K + ), cesium (Cs + ), barium (Ba 2+ ), strontium (Sr 2+ ), calcium (Ca 2+ ), sodium (Na + ), and magnesium (Mg 2+ ) may also be used. Those skilled in the relevant art will recognize that other compounds are suitable for providing an electrolyte  36  to the electrolyzer process  100 . Direct current (DC) electricity  28  fed to the electrolyzer process  100  provides the necessary electricity  28  for producing hydrogen  32 . Makeup water  34  is added as required. Electrolyte  36  is added as needed to maintain proper concentration. 
     An electrical power selection and conditioning module  14  enables the hydrogen system  10  to provide DC electricity  28  from a variety of sources which are appropriately connected thereto. By way of example only, such sources include solar panels  22 , wind turbines  24 , batteries  26 , and the conventional power grid  16 , which alternating current (AC) electricity  18  may be converted to DC by an AC-DC rectifier which may be included in the power selection and conditioning module  14 . It will be appreciated by those skilled in the relevant art that sources other than those shown and discussed may also provide the necessary electric power  28 . Advantageously, excess power from, for example, solar panels  22  or wind turbines  24 , not required to operate the electrolyzer process  100 , may be fed back into the grid  16  for credit or utilized in a residence, business, or other property. 
     As shown in  FIG. 1 , oxygen  30  may be vented to the atmosphere or further processed for other uses. Hydrogen  32  produced by the electrolyzer process  100  may be sent to storage  12  for further use and may be compressed (not shown) for storage at higher pressures as required. In a residential setting, for example, the hydrogen  32  may be used to fill an onboard supply vessel, for example, with a vehicle  42 . Conventional stationary appliances  44  such a furnace, water heater, stove or oven, an absorption air conditioner or refrigerator, electrical generator, or fuel cell may be powered by the hydrogen  32 . Finally, excess heat from the electrolyzer  102  or a hydrogen or oxygen collector  104 ,  106  (described more fully below) may help further reduce heat demands. 
     The electrolyzer  102  and selected ancillary components are shown in  FIG. 2 . An electrolyzer  102  (described more fully below) receives water via the hydrogen collector  104  and the oxygen collector  106  (both described more fully below). The hydrogen collector  104  collects hydrogen  32  generated by the electrolyzer  102  and the oxygen collector  106  collects oxygen  30  generated by the electrolyzer  102 . 
     In an exemplary embodiment as shown in  FIG. 2 , the electrolyzer  102  is enclosed within a sealed electrolyzer enclosure  108  and the hydrogen and oxygen collectors  104 ,  106  are enclosed within a sealed collector enclosure  110 . Water or other suitable heat transfer fluid may be circulated through the electrolyzer enclosure  108  and around the electrolyzer  102  as indicated by electrolyzer enclosure circulating heat transfer fluid in  112  and electrolyzer enclosure circulating heat transfer fluid out  114 . The electrolyzer enclosure circulating heat transfer fluid circulating through the electrolyzer enclosure  108  may be heated by the electrolyzer  102  to, for example, 115 deg. F. and may be subsequently used for space heating or for heating hot water, especially in a residence. Air or other suitable heat transfer fluid may be circulated through the collector enclosure  110  and around the hydrogen and oxygen collectors  104 ,  106  as indicated by collector enclosure circulating heat transfer fluid in  116  and collector enclosure circulating heat transfer fluid out  118 . The collector enclosure circulating heat transfer fluid circulating through the collector enclosure  110  is heated by the hydrogen and oxygen collectors  104 ,  106  to, for example, 130 deg. F. and may subsequently be used for space heating, heating hot water, or for powering an absorption air conditioner or refrigerator. In an exemplary embodiment, the electrolyzer enclosure  108  and the collector enclosure  110  are constructed with ¾-inch high density polyethylene (HDPE) panels and appropriately sealed to contain the circulating heat transfer fluid. 
       FIGS. 3 and 4  combine to illustrate an exemplary embodiment of a multi-cell electrolyzer  102 . Going through in order, first is a stack closed end compression plate  200 . In the illustrated embodiment, the stack closed end compression plate  200  has no means for allowing process streams in or out. Such connections are at the far end of the stack  102 . In an exemplary embodiment, the stack closed end compression plate  200  is ¾-inch hot-rolled steel. The stack closed end compression plate  200  may also comprise a material such as cold-rolled steel, composite, or other material with sufficient strength. The stack closed end compression plate  200  includes a plurality of stack compression bolt holes  202 . In the illustrated embodiment, there are 16 stack compression bolt holes  202  which receive a like number of stack compression bolts (not shown). The stack closed end compression plate  200  cooperates with a stack open end compression plate  290  ( FIG. 4 ) and the plurality of stack compression bolts (not shown) to hold together and compress the electrolyzer  102 . Also, in an exemplary embodiment, the stack closed end compression plate  200  includes an electrical stud hole  204  to receive, and to allow for protrusion of, an electrical stud  232  attached to an anode  230 . The electrical stud  232  enables electrical current to be applied to the electrolyzer  102 . As will be appreciated by those skilled in the relevant art, the anode  230  and the cathode  231  ( FIG. 4 ) may be reversed and the ancillary collection equipment modified accordingly. In the illustrated embodiment, the stack closed end compression plate  200  further includes a stack lift tongue  206  including a stack lift hole  208  for facilitating lifting and transporting the electrolyzer  102 . In an exemplary embodiment, the surface of the stack closed end compression plate  200  facing the stack closed end insulator plate  220  is treated with blanchard grinding. 
     Adjacent the stack closed end compression plate  200  is a stack closed end insulator plate  220 . In an exemplary embodiment, the stack closed end insulator plate  220  is ¾-inch HDPE. Other non-conductive materials with sufficient strength and heat resistant properties, such as low density polyethylene (LDPE), polyurethane, nylon, and ceramic materials could be satisfactory. The stack closed end insulator plate  220  includes a series of stack compression bolt holes  202 . In the illustrated embodiment, there are 16 stack compression bolt holes  202  which receive a like number of stack compression bolts (not shown). Also, in an exemplary embodiment, the stack closed end insulator plate  220  includes an electrical stud hole  204  to receive, and to allow for protrusion of, the electrical stud  232  attached to the anode  230 . The stack closed end insulator plate  220  may further include a set of seals (not shown) such as O-rings seated in a like set of seal grooves (not shown) formed to seal one or more water inlets  234  an oxygen outlet  236  and a hydrogen outlet  238  formed in the anode  230 . 
     Adjacent to the stack closed end insulator plate  220  is the anode  230 . The anode  230  includes the electrical stud  232  attached thereto which may be threaded for ease of connection to DC electrical power. As will be appreciated by those skilled in the relevant art, the anode  230  may be connected to DC electrical power in a number of ways, including, but not limited to, one or more tabs along the side edges of the anode  230 . In an exemplary embodiment, the anode  230  is constructed of 11-gauge 316 stainless steel. In the illustrated embodiment, the anode  230  includes  16  stack compression bolt holes  202  which receive a like number of stack compression bolts (not shown). As assembled, the anode  230  is placed so its electrical stud  232  protrudes through the electrical stud holes  204  formed in the stack closed end insulator plate  220  and the stack closed end compression plate  200  and is connected to DC electrical power. In an exemplary embodiment, the anode  230  is formed with an oxygen outlet  236 , a hydrogen outlet  238 , and one or more water inlets  234 . 
     Adjacent to the anode  230  is a first end frame  240 . Shown in  FIG. 3  is the anode side of the first end frame  240 . In an exemplary embodiment, the first end frame  240  is HDPE. As with the insulator plates  220 ,  280  ( FIG. 4 ), and the interior frames  260  ( FIGS. 3 and 4 ), the end frames  240  could comprise LDPE, polyurethane, nylon, or ceramic material. The first end frame  240  includes a chamber aperture  248  and, in the illustrated embodiment, 16 stack compression bolt holes  202  which receive a like number of stack compression bolts (not shown). The first end frame  240  further includes at least one water inlet  234 . In the illustrated embodiment, the anode side of the first end frame  240  includes at least one channel  244  formed between the at least one water inlet  234  and the chamber aperture  248  and, thus, provides fluid connectivity between the water inlet  234  and the chamber aperture  248 . In the illustrated embodiment, the anode side of the first end frame  240  includes at least one channel support  246 . (Shown in analogous fashion in  FIG. 5 .) The at least one channel support  246  helps maintain the integrity of the channel  244  when the electrolyzer  102  is under compression. 
     The first end frame  240  further includes an oxygen outlet  236  and a hydrogen outlet  238 . In the illustrated embodiment, the anode side of the first end frame  240  includes a channel  244  formed between the oxygen outlet  238  and the chamber aperture  248 . In the illustrated embodiment, the anode side of the first end frame  240  includes at least one channel support  246  ( FIG. 5 ). The reverse side of the first end frame  240 , which faces, and is adjacent to, a first membrane assembly  250 , is described herein below when describing a membrane assembly side of a first interior frame  260 . 
     Referring again to  FIG. 3 , adjacent to the first end frame is the first membrane assembly  250 . In an exemplary embodiment, the first membrane assembly  250  comprises a membrane  256  and an associated membrane gasket  254 . In a further exemplary embodiment, the membrane  256  is ripstop nylon with a thread count per square inch of 118×92 and with a weight per square yard of about two ounces. Ripstop nylon is durable and less-expensive than alternative materials and it is resistant to chemical attack by caustic feedwater  40 . In an exemplary embodiment, the nylon used in the membrane material is nylon 6,6. In a further exemplary embodiment, the nylon used in the membrane material is nylon 6. In an exemplary embodiment, the ripstop nylon membrane  256  is treated with a fluorocarbon-based water-repellent. In a further exemplary embodiment the ripstop nylon membrane  256  is not so treated. When wet, the membrane  256  enables electrons to selectively pass through. Additionally, and although not wishing to be bound by any particular theory, it is believed that the structure of the ripstop nylon material, with its inter-woven ripstop reinforcement threads in a crosshatch pattern, may effect a concentration of current density and improve cell efficiency. 
     In an exemplary embodiment, the membrane may also comprise other synthetic fabric materials. Polyamides, of which nylon is at type, also include aramids, a class of strong, heat-resistant fibers comprising aromatics. 
     The membrane gasket  254  effects a seal of the membrane  256  when included in the electrolyzer  102 . In an exemplary embodiment, the membrane gasket  254  comprises plastisol bonded to a border of the membrane  256 . The plastisol may be applied via a silkscreen process. The border of one side of the membrane  256  is coated with plastisol and heated, typically in an oven, sufficiently to bond the plastisol to the membrane  256 , in one exemplary embodiment, generally between about 140 deg. C. and about 170 deg. C. for between about 45 seconds and about 60 seconds. In another exemplary embodiment, about 175 deg. C. for about 90 seconds. The membrane  256  is then turned over and the border of the other side of the membrane  256  is coated with plastisol and heated as before. The bonds are complete after about 72 hours. Before treating with plastisol to form the membrane gasket  254 , the original dimensions of the membrane  256  are larger to accommodate shrinkage in the heating process. 
     The membrane gasket  254  comprises at least one water inlet  234 , an oxygen outlet  236 , a hydrogen outlet  238 , and a series of stack compression bolt holes  202 . A die punch may be used to form these holes, inlets, and outlets and may include a series of alignment jig posts (not shown). A series of alignment marks or holes  252  may be included on the membrane assembly  250  which cooperate with the die punch alignment jig posts to enable the membrane assembly  250  to be properly aligned on the die punch. 
     Plastisols are used to print textiles and are composed primarily of polyvinyl chloride (PVC) resin, typically a white powder, and a plasticizer, typically a thick, clear liquid. Optionally, a colorant may be added. The inks must be heated to cure, generally at temperatures in the range of 140-170 deg. C., as discussed above. The porosity of the textile permits good plastisol penetration and, therefore, good adhesion of the plastisol to the textile. When used with tightly-woven ripstop nylon, however, the plastisol may be combined with a nylon binding agent such as Nylobond™ Bonding Agent (NYBD-9120) (Union Ink Co., Ridgefield, N.J.). In an exemplary embodiment, the ink is Ultrasoft PLUS (PLUS-6000) (Union Ink Co.) and is formulated. 
     In a further exemplary embodiment, the plastisol is 900-series, such as 902LF, from International Coatings Co. (Cerritos, Calif.). These plastisol formulations include a premixed bonding agent catalyst. Exemplary curing is about 175 deg. C. for about 90 seconds. 
     In an exemplary embodiment, the membrane assembly  250  is about 0.009 inches thick at the membrane gasket  254 . Under compression in the electrolyzer  102 , the membrane gasket  254  compresses and the membrane assembly  250  compresses to about 0.005 inches. 
     Referring again to  FIG. 3 , adjacent to the first membrane assembly  250  is a first interior frame  260 . Shown in  FIG. 3  is the first membrane side of the first interior frame  260 . In an exemplary embodiment, the first interior frame  260  is HDPE. The first interior frame includes a chamber aperture  248  and, in the illustrated embodiment, 16 stack compression bolt holes  202  which receive a like number of stack compression bolts (not shown). The first interior frame  260  also includes at least one water inlet  234 , an oxygen outlet  236 , and a hydrogen outlet  238 . 
     The side of the first interior frame  260  which faces an interior electrode  270  is further described herein below with the second interior frame  260 . On the interior electrode side of the first interior frame  260  is an electrode ledge  272  formed around the chamber aperture  248  into which the interior electrode  270  may nest. In an exemplary embodiment, the electrode ledge  272  has a depth of one-half the thickness of the interior electrode  270 . As will be appreciated by those skilled in the art, the interior electrode side of the first interior frame  260 , discussed below with the second interior frame  260 , and shown in detail in  FIG. 4 , includes a channel  244  (not shown, but illustrated analogously with the second interior frame  260  of  FIG. 4 ), analogous to the channel  244 , formed between the hydrogen outlet  238  (not shown, but illustrated analogously with the second interior frame  260  in  FIG. 4 ) and the chamber aperture  248 . The channel  244  may further include at least one channel support  246  ( FIG. 5 ). 
     Turning now to  FIG. 4 , adjacent to the first interior frame  260  is an interior electrode  270 . As will be appreciated by one skilled in the relevant art, the interior electrode  270  operates as a bi-polar electrode. In an exemplary embodiment, the interior electrode  270  is sized to nest within the electrode side of each interior frame  260 . In an exemplary embodiment, the interior electrode  270  is 18-gauge 316 stainless steel. 
     Adjacent to the interior electrode  270  is a second interior frame  260 . As shown in  FIG. 4 , the interior electrode side of the second interior frame  260  faces the interior electrode  270 . In an exemplary embodiment, the second interior frame  260  is HDPE. The second interior frame  260  includes a chamber aperture  248  and, in the illustrated embodiment, 16 stack compression bolt holes  202 , which receive a like number of stack compression bolts (not shown). The second interior frame  260  also includes at least one water inlet  234 , and oxygen outlet  236 , and a hydrogen outlet  238 . 
     The side of the second interior frame  260  which faces the interior electrode  270  includes an electrode ledge  272  formed around the chamber aperture  248  into which the interior electrode  270  may nest. In an exemplary embodiment, the electrode ledge  272  has a depth of one-half the thickness of the interior electrode  270 . The interior electrode side of the second interior frame  260  includes a channel  244  formed between the oxygen outlet  236  and the chamber aperture  248 . The channel  244  may further include at least one channel support  246  ( FIG. 5 ). 
     The side of the second interior frame  260  which is adjacent to, and faces, a second membrane assembly  250  is analogously shown in detail and described with the side facing the first membrane assembly  250  of the first interior frame  260  ( FIG. 3 ). 
     Adjacent to the second membrane assembly side of the second interior frame  260  is a second membrane assembly  250 , which has been described herein above with the first membrane assembly  250 . 
     Adjacent to the second membrane assembly  250  is a second end frame  240 . In an exemplary embodiment, the second end frame  240  is HDPE. The second end frame  240  includes a chamber aperture  248  and, in the illustrated embodiment, 16 stack compression bolt holes  202  which receive a like number of stack compression bolts (not shown). The second end frame  240  further includes at least one water inlet  234 , an oxygen outlet  236 , and a hydrogen outlet  238 . Shown in analogous detail in  FIG. 3 , and as described analogously above in reference to the first end frame  240 , the cathode side of the second end frame  240  further includes a channel  244  (shown in analogously in  FIG. 3  and discussed above with the first end frame  240 ) formed between the chamber aperture  248  and the hydrogen outlet  238 . Further, the channel  244  may include at least one channel support  246 . 
     Likewise, the cathode side of the second end frame  240  further includes a channel  244  formed between the chamber aperture  248  and the at least one water inlet  234 . Further, this channel  244  may include at least one channel support.  246 . 
     Adjacent to the cathode side of the second end frame  240  is the cathode  231 . The description of the cathode  231  is similar to that of the anode  230 . The cathode  231  further includes an oxygen outlet  236 , a hydrogen outlet  238 , and one or more water inlets  234 . 
     Adjacent to the cathode  231 , and interposed between the cathode  231  and a stack open end compression plate  290 , is a stack open end insulator plate  280 . While the stack open end insulator plate  280  is formed similarly to the stack closed end insulator plate  220 , the stack open end insulator plate  280  further includes at least one water inlet  234 , an oxygen outlet  236 , and a hydrogen outlet  238 . In an exemplary embodiment, the stack open end insulator plate  280  is ¾ inch HDPE. The stack open end insulator plate  280  includes a series of stack compression bolt holes  202 . In the illustrated embodiment, there are 16 stack compression bolt holes  202  which receive a like number of stack compression bolts (not shown). Also, in an exemplary embodiment, the stack open end insulator plate  280  includes an electrical stud hole  204  to receive, and to allow for protrusion of, the electrical stud  232  attached to the cathode  231 . On the cathode side of the stack open end insulator plate  280  may further include a set of seals such as O-rings (not shown) seated in a like set of grooves  284  formed to seal the one or more water inlets  234 , the oxygen outlet  236 , and the hydrogen outlet  238  formed in the cathode  231 . Likewise, a similar set of grooves  284  and seals may be included in the open end compression plate side of the open end insulator plate  280 . 
     Adjacent to the stack open end insulator plate  280  is the stack open end compression plate  290 . In an exemplary embodiment, the stack open end compression plate  290  is ¾-inch hot-rolled steel plate. The stack open end compression plate  280  may also comprise a material such as cold-rolled steel, composite, or other material with sufficient strength. In an exemplary embodiment, the surface of the stack open end compression plate  290  facing the stack open end insulator plate  280  is treated with blanchard grinding. The stack open end compression plate  290  also includes at least one water inlet  234 , an oxygen outlet  236 , and a hydrogen outlet  238 . Along a periphery of the stack open end compression plate  290  are a plurality of stack compression bolt holes  202 . In the illustrated embodiment, there are 16 stack compression bolt holes  202  which receive a like number of stack compression bolts (not shown). Also, in an exemplary embodiment, the stack open end compression plate  290  includes an electrical stud hole  204  to receive, and to allow for protrusion of, an electrical stud  232  attached to the cathode  231 . 
     The exemplary embodiment illustrated in  FIGS. 3 and 4  shows one interior electrode  270 . Larger capacities may be assembled by adding additional interior parts. For example, a plurality of assemblies, each assembly comprising a membrane assembly  250 , a first interior frame  260 , an interior electrode  270 , and a second interior frame  260 , may be included. As appropriate, a first end frame  240 , an additional membrane assembly  250 , and a second end frame  240 , would be required. 
     Although not shown, the electrolyzer  102  may be held together with a plurality of stack compression bolts spanning the electrolyzer  102  from the stack closed end compression plate  200  and the stack open end compression plate  290 . Each compression bolt may be surrounded, substantially along its entire length, by a seal (not shown), which may also function as an insulator. By way of example only, such seal could be Parflex® (Parflex Division, Parker-Hannifin, Ravenna, Ohio) 588N-10 non-conducting, high-pressure hose. In an exemplary embodiment, the compression bolts are torqued to 55 pounds. 
     Turning now to  FIG. 11 , in an exploded view of a further exemplary embodiment, a framed electrode  270 ′ may be provided and used in multi-cell electrolyzer. The electrode  270  is partially encased within, and formed as one with, two interior frames  320  which frames  320  may comprise HDPE. In the illustrated embodiment, the channels  244  have a depth that extends to the surface of the electrode  270 . Channel supports  246  may be omitted. As illustrated in  FIG. 11 , one side of the framed electrode  270 ′ may comprise a tongue  264  and the other side a coordinating groove  266  to enhance fit and seal. Multiple framed electrodes  270 ′ could be combined with, for example, multiple framed membranes  256 ′, described below. 
     In a further exemplary embodiment shown in  FIG. 12 , a framed membrane  256 ′ may also be provided and used in multi-cell electrolyzers  102 . A membrane  256 , which may not include a membrane gasket  254 , is partially encased within, and formed as one with, two frames  330 . As shown in  FIG. 12 , the membrane  256  is large enough to extend beyond the water inlets  234  and the hydrogen  238  and oxygen  236  outlets. In addition, the associated holes in the membrane  256  (shown as  234 ′,  238 ′, and  236 ′, respectively) are larger than their counterparts. This enables the frame material (e.g., HDPE) to seal the holes  234 ,  238 , and  236 . In addition, where peripheral bolt holes  202  (not shown in  FIG. 12 ) are included, such holes in the membrane  256  may also be larger. In the illustrated embodiment, the channels  244  have a depth that does not extend to the surface of the membrane. As illustrated in  FIG. 12 , one side of the framed membrane  256 ′ may comprise a tongue  264  and the other side a coordinating groove  266  to enhance fit and seal. 
     In a further exemplary embodiment, the framed membrane  256 ′ further comprises an electrode ledge  272  ( FIG. 4 , shown associated with the interior frame  260 , e.g.) formed therein. As constructed, then, a plurality of framed membranes  256 ′ may be stacked with an interior electrode  270  inserted therebetween. 
     In an exemplary embodiment, interior frames  260  have a gross thickness at the borders of about 0.110 in. The thickness of the interior frame  260  along the edge of the electrode ledge is about 0.086 in. When torqued, the membrane assembly is about 0.005 in. This configuration results in an inter-electrode gap of about 0.177 in. 
       FIG. 6  illustrates the detail of the fabric of a ripstop nylon membrane  256 . As shown, the membrane  256  includes a pattern of ribs  300  comprising interwoven ripstop reinforcement threads in a crosshatch pattern with fabric planes  302  therebetween. 
       FIG. 5  illustrates the detail of a channel  244  between an illustrative oxygen outlet  236  and an aperture  248 . One or more channel supports  246  are shown which help keep the channel  244  from collapsing under the compressive load. Also shown in  FIG. 5  is the electrode ledge  272  for providing fit and sealing to the interior electrode  270  ( FIG. 4 ). 
     Turning now to  FIG. 7 , shown generally is the electrolyzer process  100 , the electrolyzer  102  is shown, along with the hydrogen collector  104 , the oxygen collector  106 , and a hydrogen expansion tank  105 . Feedwater  40 , which is formed from the water supply  34  and the electrolyte supply  36 , is drawn from the feedwater tank  38  ( FIG. 1 ). Feedwater  40  is supplied by a pump  126  and managed by a solenoid valve  132  which are described more fully herein below. As can be seen in  FIG. 7 , feedwater  40  may be balanced throughout the electrolyzer process  100  and provides feedwater  40  in the electrolyzer  102 , the hydrogen collector  104 , and the oxygen collector  106 . The feedwater  40  enters the electrolyzer  102  through the one or more water inlet  234 , shown illustratively in  FIG. 7  as two water inlets  234 . Feedwater  40  also provides a controlled liquid level in the hydrogen collector  104  and the oxygen collector  106 , the control of which is described more fully herein below. An electrical supply  156  and power supply  134  are also provided and shown in  FIG. 7 . In the illustrated embodiment, 250VDC power is supplied to the cathode  231  (not shown) and to the anode  230  (not shown) through the electrical studs  232 . During operation, hydrogen  32  and oxygen  30  are withdrawn from the electrolyzer  102  through the hydrogen outlet  238  and oxygen outlet  236 , respectively. 
     The hydrogen collector  104  may include appropriate liquid level sensors and transmitters. Four such instruments are shown in  FIG. 7 . A water level high transmitter  136  indicates when the water level in the hydrogen collector  104  is high. A water level low transmitter  148  indicates when the water level in the hydrogen collector  104  is low. A pair of water level transmitters  140 ,  144  initiate turning off and on, respectively, the feedwater pump  126 . As will be appreciated by those skilled in the art, the functions of these multiple level transmitters may be provided by as few as one sophisticated level transmitter. At the outlet of the hydrogen collector  104  is a hydrogen relief valve  128 . 
     The illustrative embodiment shown in  FIG. 7  further includes a hydrogen expansion tank  105  downstream of the hydrogen collector  104 . In an exemplary embodiment, the hydrogen expansion tank  105  helps stabilize the levels of water in the hydrogen collector  104  and the oxygen collector  106  when starting up with pressure preexisting in the hydrogen storage  12  ( FIG. 1 ). A hydrogen expansion tank  105  having a volume of about 0.58 times the oxygen collector  106  should accomplish feedwater level stability long enough for the pressure in the electrolyzer process  100  to rise above the pressure in the hydrogen storage  12  ( FIG. 1 ) and allow hydrogen to flow from the hydrogen collector  104  to the hydrogen storage  12  ( FIG. 1 ). Lacking this feature, the feedwater level in the hydrogen collector  104  could drop enough to prematurely activate the feedwater pump  126  which could cause the electrolyzer process  100  to overfill with feedwater  40 . In such case, as the electrolyzer process  100  becomes overfilled, as described above, when the system reaches pressure above that of the hydrogen storage  12 , the water in the hydrogen collector  104  will reach the high water level fault indicator before the oxygen release valve  130  on the oxygen collector  106  is triggered by the level transmitter  150 . Thus, unwanted or unnecessary shutdowns are avoided. Alternatively, the hydrogen collector  104  may be sized sufficiently larger than the oxygen collector  106 . 
     Associated with the oxygen collector  106 , and downstream thereof, is an oxygen sensor  158  (e.g., Bosch 13275). The oxygen sensor  158  is used to detect, by inference, hydrogen in the oxygen  30 . Of course, a second oxygen sensor  158  could be used to detect oxygen in the hydrogen  32 . Also included with the oxygen collector  106  may be a pressure relief valve  172 . 
     The oxygen collector  106  may also include appropriate liquid level sensors and transmitters. Six such instruments are shown in  FIG. 7 . A water level high transmitter  138  indicates when the water level in the oxygen collector  106  is high. A water level low transmitter  154  indicates when the water level in the oxygen collector  106  is low. In addition, a series of sensors and transmitters control the discharge of oxygen  30  from the oxygen collector  106 . In the illustrated embodiment, there are a pair of oxygen-off transmitters  142 ,  146  that effect the closing of an oxygen release control valve  130 . In operation, when the water level in the oxygen collector  106  rises to either oxygen-off transmitter  142 ,  146 , the oxygen release control valve  130  is closed and remains closed until the water level lowers to a point which activates either oxygen-on transmitter  150 ,  152  at which time the oxygen release control valve  130  is opened and remains open until the water level rises and actuates oxygen-off transmitter  142 ,  146  at which time the oxygen release control valve  130  is closed. During operation this cycle repeats to continuously balance the electrolyzer process  100  and remains active even if the electrolyzer process  100  is not active. As will be appreciated by those skilled in the relevant art, the functions of these multiple level transmitters may be provided by as few as one sophisticated level transmitter. 
     Further illustrated in the exemplary embodiment shown in  FIG. 7  are one or more heat transfer coils  107  which can effectively utilize excess heat. Shown in  FIG. 7  is a coil  107  within each collector  104 ,  106  and in combination with a fan  120 . A pump  124  circulates a suitable heat transfer fluid (e.g., water) through the collectors  104 ,  106  and the heat sink  107  associated with the fan  120 . The excess heat recovered from the collectors  104 ,  106  may be utilized, for example, in space heating or by placing a coil  107  downstream of the air handler of a forced air furnace. 
     Circuit Diagrams 
     The following tables are intended to provide exemplary values for the electronic circuit elements shown in  FIGS. 8-10  and described herein. 
     Resistors (Ω) 
                                                     R1 = 100K   R2 = 100K   R3 = 10   R4 = 47K   R5 = 100K   R6 = 100       R7 = 22K   R8 = 470   R9 = 100K   R10 = 100K   R11 = 470   R12 = 470       R13 = 100   R14 = 100   R15 = 100K   R16 = 100K   R17 = 470   R18 = 47K       R19 = 100K   R20 = 470   R21 = 22K   R22 = 100K   R23 = 100K   R24 = 470       R25 = 47   R26 = 100   R27 = 100K   R28 = 47K   R29 = 22K   R30 = 470       R31 = 10meg   R32 = 100K   R33 = 100K   R34 = 0.001                    
Capacitors (μf)
 
                                                 C1 = 0.001   C2 = 0.001   C3 = 100   C4 = 100   C5 = 0.1       C6 = 0.001   C7 = 0.001   C8 = 0.001   C9 = 0.001   C10 = 4700       C11 = 0.001   C12 = 0.001   C13 = 0.001                    
Transistors (MOSFET)
 
                                                     T1 = 2984   T2 = 2984   T3 = 2984   T4 = 2984   T5 = 2984   T6 = 2984       T7 = 2984   T8 = 2984   T9 = 2984   T10 = 2984                    
Amplifiers
 
A1=NTE 943 A2=NTE 943 A3=NTE 943
 
Integrated Circuits
 
                                                 IC1 = 4013   IC2 = 555   IC3 = 960   IC4 = 4013   IC5 = 960       IC6 = 4013   IC7 = 4013                    
Diodes
 
                                                     D1 = high   D2 = 1N914   D3 = power   D4 = H 2  storage   D5 = 1N914   D6 = water       temperature       on   tank full       level fault       D7 = 1N914   D8 = H2 in   D9 = pump   D10 = 1N914   D11 = 1N914   D12 = system           O 2  fault   on           warm                    
Switches
 
                                                     S1 = control   S2 = control   S3 = continuous   S4 = 136-H 2     S5 = 138-O 2     S6 = 148-H 2         system off   system on   or pulsed   water high   water high   water low               operation       S7 = 154-O 2     S8 = 142-O 2     S9 = 146-O 2     S10 = 150-O 2     S11 = 152-O 2     S12 = 140-       water low   release closed   release closed   release open   release open   feedwater                           pump off       S13 = 144-       feedwater       pump on                    
Contactors
 
     
       
         
               
               
               
               
               
               
             
           
               
                   
               
             
             
               
                 Coil K1 and 
                 Coil K2 and 
                 Coil K3 and 
                 K4 = K4-over 
                 K5 = K5- 
                 K6 = K6- 
               
               
                 contact K1- 
                 contact K2- 
                 contact K3- 
                 temperature 
                 solid state relay 
                 solid state relay 
               
               
                 energizes coil 
                 time delay 
                 battery saver 
                 redundancy 
               
               
                 K2 
                 operates 
                 circuit 
               
               
                   
                 pump and water 
               
               
                   
                 input solenoid 
               
               
                   
               
             
          
         
       
     
     Looking first at  FIG. 8 , a power logic circuit  400  controls the overall control scheme. Power logic circuit  400  cooperates with the water level fault circuit  440  to shut off power if the water level becomes unbalanced. For example, if either of switches S 4 -S 7  are closed (see, also,  FIG. 7 ), a fault condition is indicated at D 6  and a fault condition goes from fault output  442  to fault input  402 . The power logic circuit  440  also cooperates with the oxygen sensor circuit  460  ( FIG. 10 ) to shut off power if an unsafe level of hydrogen arises in the oxygen (see, also,  FIG. 7 ). For example, if the oxygen sensor  158  detects an unsafe level of hydrogen in the oxygen, a fault condition is indicated at D 8  and a fault condition goes from fault output  462  to fault input  402 . 
     An operational temperature circuit  410  monitors heat levels in the electrolyzer  102 . A thermistor  174  (see, also,  FIG. 7 ) actuates when an unsafe temperature level (e.g., 160 deg. F.) is reached. This condition is indicated by LED D 1 . This shuts off the power to the electrolyzer  102 , which remains off until the temperature drops below the preset temperature level. Thus, the electrolyzer  102  turns on and off to keep the electrolyzer  102  within a safe temperature regime. 
     An intermittent/pulsed operation circuit  420  provides adjustable intermittent power through a switch S 3  to the electrolyzer  102  to regulate heat and to improve efficiency. This circuit also enables varying modes of operation of the electrolyzer  102 . For example, the circuit may be cycled on-and-off at intervals from about one second to about two minutes or greater. This allows the hydrogen and oxygen to clear the electrodes, thereby increasing the effective surface area of the electrode. In addition, such intermittent operation assists in controlling the heat of the hydrogen generation system. In addition, the intermittent/pulsed operation circuit can enable the hydrogen system  10  to more effectively utilize power available from the wind turbine  24  ( FIG. 1 ). An intermittent no-load condition of the wind turbine  24  allows it to gain inertia in low wind conditions. Then, when a load is applied, the kinetic energy of the spinning turbine  24  is applied to the electrolyzer  102 . 
     A pressure switch circuit  430  controls the pressure in the hydrogen storage  12  ( FIG. 1 ) via a pressure switch  170 . As long as the pressure switch  170  is closed, indicating below preset maximum pressure in the hydrogen storage  12 , MOFSET T 4  conducts to coils K 5  and K 6  which are operably connected to contacts K 5  and K 6  (shown in the power supply circuit  490 ,  FIG. 9 , discussed below) and power remains on. When the pressure in the hydrogen storage  12  reaches the preset maximum pressure, power to the electrolyzer  102  is shut off. Normal operation is indicated at an LED D 3  and a full pressure condition in the hydrogen storage  12  is indicated at an LED D 4 . When the pressure in the hydrogen storage  12  drops below a preset pressure condition, indicating there is room for more hydrogen in the hydrogen storage  12 , power to the electrolyzer  102  is turned back on. 
     A water level fault circuit  440  monitors the water levels in the collection towers  104 ,  106  and shuts off power if the water level becomes unbalanced. The water level fault circuit  440  cooperates with the power logic circuit  400  discussed above. 
     Associated with the pump control circuit  450   a , shown in  FIG. 8 , is a pump control circuit  450   b  shown in  FIG. 9 . And, shown associated with the pump control circuit  450   b  are two switches, switch S 12 , which is operably connected to the water pump off level transmitter  140  on the hydrogen collector  104 , and switch S 13 , which is operably connected to the water pump on level transmitter  144  on the hydrogen collector  104 . In operation, when level transmitter  144  senses a need for feedwater  40 , coil K 1  is energized in the pump control circuit  450   b  ( FIG. 9 ) which closes contact K 1  in the pump control circuit  450   a  ( FIG. 8 ). The closing of contact K 1  energizes coil K 2  of the pump control circuit  450   a  which closes contact K 2  of the pump control circuit  450   a , thus powering the feedwater pump  126  ( FIGS. 7 and 8 ) and opening the feedwater solenoid valve  132  ( FIG. 7 ). When the level transmitter  140  on the hydrogen collector  104  senses sufficient feedwater  40 , coil K 1  is de-energized and the feedwater pump  126  is turned off and the feedwater solenoid valve  132  is closed. Coil K 2  de-energizes after a preset time and must be reset in order to be reactivated. This provides protection to the pump  126  in such case when the feedwater  40  has been turned off or is empty. It also helps prevent overfilling in the event water level transmitter  140  fails. 
     Turning now to  FIG. 10 , the oxygen sensor circuit  460  interprets the voltage levels of the oxygen sensor as it correlates to the proportion of hydrogen in the oxygen. The oxygen sensor circuit  460  cooperates with the power logic circuit  400  ( FIG. 8 ). The oxygen sensor circuit  460  will shut down the electrolyzer process  102  if the level of hydrogen in the oxygen  30  reaches unsafe levels by energizing a fault output  462  which is fed into the fault input  402  of the power logic circuit  400 . An indicator LED D 8  is also illuminated. 
     A battery saver circuit  470  shown in  FIG. 9  is designed to automatically disconnect a battery  476  from the control circuits, thus preventing complete discharge of the battery  476  in the event of an extended power failure. This disconnect will occur if a power interruption lasts longer than about eight hours. The battery saver circuit  470  automatically reconnects the battery  476  when power is restored. The eight hours of standby allows for cool down and release of pressure by the control circuits in case of a power failure. This helps prevent the control circuits from draining the battery  476  in the event of an extended power outage. 
     In operation, when AC power is present, the standby transformer  472  supplies power to the rectifier diode D 10  which feeds IC 5 . The output of IC 5  then charges capacitor C 10  through blocking diode D 11 . When charge is sufficient, the logic level MOSFET T 10  conducts and energizes coil K 3 . This connects the battery  476  to the control circuits and a 12VDC power supply via a normally-open contact K 3 . If AC power is removed, or a power outage is experienced for e.g., eight hours or other preset time, the MOSFET T 10  de-energizes K 3  which effectively disconnects the battery  476 . 
     A warm-up circuit  480  monitors the warm-up phase of the operation of the electrolyzer process  100  and regulates the pressure inside the electrolyzer  102 . An LED D 12  is illuminated when the electrolyzer process  100  reaches operational temperature. With further reference to  FIG. 7 , during the warm-up phase, a hydrogen relief valve  128  is opened to vent the hydrogen  32  being produced to prevent any pressure from developing until the electrolyzer  102  reaches a preset and adjustable temperature that causes the electrolyzer  102  to expand and tightens the seals to hold pressure. In the alternative, a flare system may be provided to burn hydrogen being vented. The hydrogen relief valve  128  is then closed and the hydrogen  32  is further processed, in, for example, a dryer  122  and sent to hydrogen storage  12  ( FIG. 1 ). If power to the electrolyzer process  100  is shut down for a period of time that would be sufficient for the electrolyzer  102  to contract, the bypass valve  128  is reopened to relieve all pressure from the electrolyzer  102  to prevent damage. 
     A power supply circuit  490  controls the main power to the electrolyzer  102 . In an exemplary embodiment, a rectifier  498  converts 240VAC to 250VDC using two NTE6036 diodes and two NTE6037 diodes. As a redundant backup to the high temperature circuit  410  which includes thermistor  174 , a thermal fuse  496 , set to 180 deg. F. or whatever reform temperature of the material used in the electrolyzer  102 , for example HDPE, helps protect the electrolyzer  102  from a thermal overload. If the thermal fuse  496  is tripped, a coil K 4  is de-energized and two contacts K 4  are opened, shutting off power to the electrolyzer  102 . In addition, de-energizing coils K 5  and K 6  opens contacts K 5  and K 6  to shut off power to the electrolyzer  102 . This may be effected by such conditions as a water level fault  442 , the off button S 1 , a high temperature condition, oxygen mix, the intermittent circuit  420 , or the pressure switch  170 . Also shown in  FIG. 9  is a fan  499  to help cool the rectifier  498  and solid state relays K 5  and K 6 . 
     Also shown in  FIG. 9  is a water level balance circuit  500  which is operably connected to the electrolyzer process  100 . Switches S 8  and S 9 , associated with level transmitters  142  and  146 , respectively, cause the oxygen release solenoid  130  ( FIGS. 7 and 9 ) to be closed. Conversely, switches S 10  and S 11 , associated with level transmitters  150  and  152 , respectively, cause the oxygen release solenoid  130  to be open. Thus, the water level in the electrolyzer process  100  is balanced. 
     Test Results 
     Tests were performed on an electrolyzer having the following configuration: 
     
       
         
               
               
               
               
             
           
               
                   
               
             
             
               
                 Number of Cells 
                 111 cells 
                 Electrode 
                 11 × 11 
               
               
                   
                   
                 Size 
                 inches 
               
               
                 Inter-electrode 
                 0.177 inches 
                 Feedwater 
                 5 oz. NaOH 
               
               
                 Gap 
                   
                   
                 per 
               
               
                 Nominal Voltage 
                 240 VAC (converted 
                   
                 5 gal. 
               
               
                   
                 to DC with four 85-amp 
                   
                 distilled 
               
               
                   
                 diodes in a bridge 
                   
                 water 
               
               
                   
                 configuration) 
               
               
                   
               
             
          
         
       
     
     Test 1 
     
       
         
               
               
               
               
             
           
               
                   
               
             
             
               
                 Time 
                 4.5 minutes 
                 Average Voltage 
                 253.3 V 
               
               
                 Average Amperage 
                 27.43 amps 
                 KWH 
                 0.5211 KWH 
               
               
                 H2 Produced 
                 4.32 scf 
                 H2 Conversion 
                 0.0791 KWH/ 
               
               
                   
                   
                   
                 cu. ft. H2 
               
               
                 H2 KWH Equivalent 
                 0.34 KWH 
                 Efficiency 
                 65.2 percent 
               
               
                   
               
             
          
         
       
     
     Test 2 
     
       
         
               
               
               
               
             
           
               
                   
               
             
             
               
                 Time 
                 1 hour 
                 Average Voltage 
                 240 V 
               
               
                 Average Amperage 
                 35 amps 
                 KWH 
                 8.4 KWH 
               
               
                 H2 Produced 
                 66.84 scf 
                 H2 Conversion 
                 0.0791 KWH/ 
               
               
                   
                   
                   
                 cu. ft. H2 
               
               
                 H2 KWH Equivalent 
                 5.28 KWH 
                 Efficiency 
                 62.9 percent 
               
               
                   
               
             
          
         
       
     
     Test 3 
     
       
         
               
               
               
               
             
           
               
                   
               
             
             
               
                 Time 
                 9 minutes 
                 Average Voltage 
                 246.5 V 
               
               
                 Average Amperage 
                 36.76 amps 
                 KWH 
                 1.36 KWH 
               
               
                 H2 Produced 
                 11.36 scf 
                 H2 Conversion 
                 0.0791 KWH/ 
               
               
                   
                   
                   
                 cu. ft. H2 
               
               
                 H2 KWH Equivalent 
                 0.90 KWH 
                 Efficiency 
                 66.1 percent 
               
               
                   
               
             
          
         
       
     
     While certain preferred embodiments of the present invention have been disclosed in detail, it is to be understood that various modifications may be adopted without departing from the spirit of the invention of scope of the following claims.

Technology Category: 4