Method and molten salt electrolytic cell for implementing a hydrogen fuel, sustainable, closed clean energy cycle on a large scale

Abstract

A hydrogen fuel, sustainable, closed clean energy cycle based on green chemistry is presented for large scale implementation using a cost effective electrolytic cell. A chemical reaction between salinated (sea) or desalinated (fresh) water (H.sub.2O) and sodium (Na) metal produces hydrogen (H.sub.2) fuel and sodium hydroxide (NaOH) byproduct. The NaOH is reprocessed in a solar powered electrolytic Na metal production plant that can result in excess chlorine (Cl.sub.2) from sodium chloride (NaCl) in sea salt mixed with NaOH, used to effect freezing point lowering of seawater reactant for hydrogen generation at reduced temperatures. The method and molten salt electrolytic cell enable natural separation of NaCl from NaOH, thereby limiting excess Cl.sub.2 production. The recovered NaCl is used to produce concentrated brine solution from seawater for hydrogen generation in cold climates, or becomes converted to sodium carbonate (Na.sub.2CO.sub.3) via the Solvay process for electrolytic production of Na metal without Cl.sub.2 generation.

Claims

1. A method for implementing a hydrogen fuel, sustainable, closed clean energy cycle on a large scale using solar powered electrolysis by means of a cost effective electrolytic cell capable of performing electrolysis on three types of molten salts individually including sodium hydroxide (NaOH), sodium chloride (NaCl), sodium carbonate (Na.sub.2CO.sub.3) or on a mixture of sodium hydroxide (NaOH) and sodium chloride (NaCl), including selective electrolysis between sodium hydroxide (NaOH) and sodium chloride (NaCl) at temperatures ranging between 1223.15 K (950 C.) to 1323.15 K (1050 C.), well above the boiling point temperature of sodium (Na) metal, comprising the steps of: generating high purity hydrogen (H.sub.2) fuel on demand in a hydrogen generation apparatus using controlled chemical reactions between either ordinary salinated (sea) or desalinated (fresh) water (H.sub.2O) and sodium (Na) metal or sodium hydride (NaH) reactants wherein said controlled chemical reactions produce high purity hydrogen (H.sub.2) fuel and chemical byproduct wherein said chemical byproduct comprises pure sodium hydroxide (NaOH) or sodium hydroxide (NaOH) mixed with sea salt and wherein said sea salt comprises substantially sodium chloride (NaCl); and recovering said chemical byproduct from said hydrogen generation apparatus and transporting said chemical byproduct including said pure sodium hydroxide (NaOH) or said mixture of sodium hydroxide (NaOH) and sodium chloride (NaCl) to a self-contained solar powered electrolytic sodium (Na) metal production plant wherein said chemical byproduct is loaded into said cost effective electrolytic cell operating within said self-contained solar powered electrolytic sodium (Na) metal production plant; and electrolyzing said pure sodium hydroxide (NaOH) to recover said sodium (Na) metal; and deciding that if chlorine (Cl.sub.2) production is needed electrolyzing said mixture of sodium hydroxide (NaOH) and sodium chloride (NaCl) simultaneously at elevated electrolytic cell voltage to produce said sodium (Na) metal at said cost effective electrolytic cell cathode and steam (H.sub.2O), oxygen (O.sub.2) and chlorine (Cl.sub.2) at said cost effective electrolytic cell anode; and deciding that if chlorine (Cl.sub.2) production is not needed electrolyzing said mixture of sodium hydroxide (NaOH) and sodium chloride (NaCl) selectively at lowered electrolytic cell voltage to electrolyze only said sodium hydroxide (NaOH) wherein said sodium (Na) metal is produced at said cost effective electrolytic cell cathode and steam (H.sub.2O) and oxygen (O.sub.2) are produced at said cost effective electrolytic cell anode and wherein said sodium chloride (NaCl) remains unelectrolyzed; and deciding that if said sodium (Na) metal is not needed from said sodium chloride (NaCl) remaining unelectrolyzed recovering and mixing with seawater said sodium chloride (NaCl) remaining unelectrolyzed to produce concentrated brine solution for use as reactant in said hydrogen generation apparatus operating in cold climates; and deciding that if said sodium (Na) metal is needed from said sodium chloride (NaCl) remaining unelectrolyzed without chlorine (Cl.sub.2) production transporting said sodium chloride (NaCl) remaining unelectrolyzed to a Solvay plant wherein said sodium chloride (NaCl) remaining unelectrolyzed and sodium carbonate (CaCO.sub.3) undergo conversion to sodium carbonate (Na.sub.2CO.sub.3) product and calcium chloride (CaCl.sub.2) byproduct; and electrolyzing said sodium carbonate (Na.sub.2CO.sub.3) product in said cost effective electrolytic cell to produce said sodium (Na) metal and carbon (C) at said cost effective electrolytic cell cathode and oxygen (O.sub.2) at said cost effective electrolytic cell anode; and transporting said sodium (Na) metal produced at said cost effective electrolytic cell cathode to a solar or biohydrogen plant wherein said sodium (Na) metal reacts with hydrogen (H.sub.2) to produce said sodium hydride (NaH) and wherein said sodium hydride (NaH) is used to generate said high purity hydrogen (H.sub.2) fuel on demand in said hydrogen generation apparatus.

2. A method according to claim 1 in which said cost effective electrolytic cell comprises a crucible holding said sodium hydroxide (NaOH) or said mixture of sodium hydroxide (NaOH) and sodium chloride (NaCl) or said sodium carbonate (Na.sub.2CO.sub.3) in a molten state wherein said cost effective electrolytic cell comprises a double ended cylinder above said crucible and wherein a riser tube couples the interior space of said crucible with the interior space of said double ended cylinder above said crucible.

3. A method according to claim 2 in which said riser tube rises midway into said double ended cylinder and wherein said riser tube drops nearly to the bottom of said crucible without contacting said bottom of said crucible.

4. A method according to claim 2 in which said riser tube top end is open and said riser tube bottom end is closed wherein a plurality of holes are drilled into the sidewalls of said riser tube near said riser tube bottom end.

5. A method according to claim 2 in which a cathode electrode rod enters from said double ended cylinder top end through said riser tube top end into said interior space of said crucible without contacting said riser tube wherein said cathode electrode rod contacts said sodium hydroxide (NaOH) or said mixture of sodium hydroxide (NaOH) and sodium chloride (NaCl) or said sodium carbonate (Na.sub.2CO.sub.3) in a molten state.

6. A method according to claim 2 in which said crucible comprises iron or nickel or nickel alloy C-276 wherein said crucible comprises the anode electrode of said cost effective electrolytic cell.

7. A method according to claim 2 in which said sodium hydroxide (NaOH) or said mixture of sodium hydroxide (NaOH) and sodium chloride (NaCl) or said sodium carbonate (Na.sub.2CO.sub.3) in a molten state contained in said cost effective electrolytic cell is electrolyzed at temperatures ranging between 1223.15 K (950 C.) to 1323.15 K (1050 C.) to produce sodium (Na) metal in a vapor state wherein said sodium (Na) metal in a vapor state rises through said riser tube above said sodium hydroxide (NaOH) or said mixture of sodium hydroxide (NaOH) and sodium chloride (NaCl) or said sodium carbonate (Na.sub.2CO.sub.3) in a molten state and wherein said sodium (Na) metal in a vapor state expands and condenses inside said double ended cylinder to a liquid state.

8. A method according to claim 1 in which said cost effective electrolytic cell operating current is approximately 100,000 Amperes.

9. A method according to claim 1 in which said sodium hydroxide (NaOH) contained in said cost effective electrolytic cell is electrolyzed at temperatures ranging between 1223.15 K (950 C.) to 1323.15 K (1050 C.) using an electrolytic cell voltage of 1.78 Volts.

10. A method according to claim 1 in which said mixture of sodium hydroxide (NaOH) and sodium chloride (NaCl) contained in said cost effective electrolytic cell is electrolyzed simultaneously at temperatures ranging between 1223.15 K (950 C.) to 1323.15 K (1050 C.) using an electrolytic cell voltage of 3.19 Volts.

11. A method according to claim 1 in which said mixture of sodium hydroxide (NaOH) and sodium chloride (NaCl) contained in said cost effective electrolytic cell is electrolyzed selectively at temperatures ranging between 1223.15 K (950 C.) to 1323.15 K (1050 C.) using an electrolytic cell voltage of 1.78 Volts wherein said electrolytic cell voltage of 1.78 Volts electrolyzes said sodium hydroxide (NaOH) and wherein said electrolytic cell voltage is increased to 3.19 V to electrolyze said sodium chloride (NaCl) remaining unelectrolyzed.

12. A method according to claim 1 in which said sodium carbonate (Na.sub.2CO.sub.3) contained in said cost effective electrolytic cell is electrolyzed at temperatures ranging between 1223.15 K (950 C.) to 1323.15 K (1050 C.) using an electrolytic cell voltage of 3.68 Volts.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0027] These and other features of the subject of the invention will be better understood with connection with the Detailed Description of the Invention in conjunction with the Drawings, of which:

[0028] FIG. 1 illustrates the complete hydrogen fuel, sustainable, closed clean energy cycle method based entirely on green chemistry.

[0029] FIG. 2 illustrates the cost effective electrolytic cell that supports implementation of the hydrogen fuel clean energy cycle on a large scale by having the capability to perform electrolysis on three types of molten salts individually including NaOH, NaCl, Na.sub.2CO.sub.3 or on a mixture of NaOH and NaCl, including selective electrolysis between NaOH and NaCl at temperatures ranging between 1223.15 K (950 C.) to 1323.15 K (1050 C.), well above the boiling point temperature of sodium (Na) metal.

[0030] FIG. 3 illustrates the cost effective electrolytic cell configured to perform electrolysis using a very high current I.sub.CELL=100,000 Amperes for implementation of the hydrogen fuel clean energy cycle on a large scale, by having the capability to perform electrolysis on three types of molten salts individually including NaOH, NaCl, Na.sub.2CO.sub.3 or on a mixture of NaOH and NaCl, including selective electrolysis between NaOH and NaCl at temperatures ranging between 1223.15 K (950 C.) to 1323.15 K (1050 C.), well above the boiling point temperature of sodium (Na) metal.

[0031] FIG. 4 illustrates the calculated electrochemical potential of the electrolytic cell as a function of temperature for sodium hydroxide (NaOH) according to Reaction 2.

4Na.sup.++4OH.sup..fwdarw.4Na+2H.sub.2O+O.sub.2Reaction 2:

[0032] FIG. 5 illustrates the calculated electrochemical potential of the electrolytic cell as a function of temperature for sodium chloride (NaCl) according to Reaction 3.

2Na.sup.++2Cl.sup..fwdarw.2Na+Cl.sub.2Reaction 3:

[0033] FIG. 6 illustrates the calculated electrochemical potentials of the electrolytic cell as a function of temperature for sodium carbonate (Na.sub.2CO.sub.3) according to Reactions 4, 5 and 6.

4Na.sup.++2CO.sub.3.sup.2.fwdarw.4Na+2C+3O.sub.2Reaction 4:

4Na.sup.++2CO.sub.3.sup.2.fwdarw.4Na+2CO+2O.sub.2Reaction 5:

4Na.sup.++2CO.sub.3.sup.2.fwdarw.4Na+2CO.sub.2+O.sub.2Reaction 6:

DETAILED DESCRIPTION OF THE INVENTION

[0034] Referring to FIG. 1, a depiction is shown of the hydrogen fuel, sustainable, closed clean energy cycle meant to be implemented on a large scale using the cost effective electrolytic cell capable of performing electrolysis on three types of molten salts individually including NaOH, NaCl, Na.sub.2CO.sub.3 or on a mixture of NaOH and NaCl, including selective electrolysis between NaOH and NaCl at temperatures ranging between 1223.15 K (950 C.) to 1323.15 K (1050 C.), well above the boiling point temperature of sodium (Na) metal. The hydrogen fuel, sustainable, closed clean energy cycle method of the present invention, in a preferred embodiment consists of a hydrogen generation apparatus 10, that implements the controlled chemical reaction between either ordinary salinated (sea) or desalinated (fresh) water (H.sub.2O) and sodium (Na) metal reactants over a wide temperature range to produce high purity hydrogen (H.sub.2) fuel 11, according to following chemical reaction:

2Na+2H.sub.2O.fwdarw.H.sub.2+2NaOHReaction 1:

In warm climates, desalinated (fresh) water (H.sub.2O) reactant can be used in the hydrogen generation apparatus 10, to produce H.sub.2(g) fuel 11, and sodium hydroxide (NaOH). The sodium hydroxide (NaOH) byproduct is recovered and transported 12, for reprocessing in a self-contained solar powered electrolytic sodium (Na) metal production plant 13, to recover the Na metal for reuse in generating H.sub.2(g) fuel 11, according to the following reaction:

4Na.sup.++4OH.sup..fwdarw.4Na+2H.sub.2O+O.sub.2Reaction 2:

Using electric power 14, generated from an array of photovoltaic panels for electrolysis to reprocess NaOH according to Reaction 2, enables elimination of carbon dioxide (CO.sub.2) emissions. If concentrated sea salt in seawater solution is used for operation of the hydrogen generation apparatus 10, in cold climates, then the self-contained solar powered electrolytic sodium (Na) metal production plant 13, will implement electrolysis on a mixture of NaOH and sea salt, the latter consisting primarily of sodium chloride (NaCl) according to the following reactions:

4Na.sup.++4OH.sup..fwdarw.4Na+2H.sub.2O+O.sub.2Reaction 2:

2Na.sup.++2Cl.sup..fwdarw.2Na+Cl.sub.2Reaction 3:

The byproduct mixture of NaOH and NaCl recovered from the hydrogen generation apparatus 10 units during motor vehicle refueling is transported 12, by truck, rail car or pipeline to self-contained solar powered electrolytic sodium (Na) metal production plants 13, for recovery of Na metal. The cost effective electrolytic cells at the plant are charged with the aqueous mixture of NaOH.sub.(aq) and NaCl.sub.(aq). The plant management then decides whether chlorine (Cl.sub.2) production is needed 15. If the response is affirmative 16, then the electrolytic cell voltage is set to V.sub.CELL=3.19 V that results in the decomposition of the entire contents of the cell including both fused NaOH.sub.(l) and NaCl.sub.(l) 17, at a cell operating temperature above the boiling point of sodium (Na) metal, to yield H.sub.2O.sub.(g), O.sub.2(g) and Cl.sub.2(g) 18, at the anode and more Na metal 19, at the cathode than had been previously used to fuel the hydrogen generation apparatus 10. The electrolysis of fused NaOH.sub.(l) and NaCl.sub.(l) 17, can occur simultaneously or sequentially by using the difference in decomposition potentials between the NaOH and NaCl. The Cl.sub.2(g) is separated from the steam (H.sub.2O.sub.(g)) and oxygen (O.sub.2(g)) 18, effluent gases generated at the anode of the cell to be bottled and later sold to manufacturers including paper, polymer (plastic) and chemical industries. The sodium (Na) metal 19, produced at the cathode of the cell is hermetically packaged for reuse in the hydrogen generation apparatus 10 units to produce H.sub.2(g) fuel 11. Alternatively, the sodium (Na) metal 19, produced at the cathode of the cell can be sent to a solar or biohydrogen plant 20, to produce sodium hydride (NaH) 21, that can also be used in the hydrogen generation apparatus 10 units to produce H.sub.2(g) fuel 11. If however, the plant management decides that Cl.sub.2 production is not needed 22, then the electrolytic cell voltage is set to V.sub.CELL=1.78 V that results in the selective decomposition of only the fused NaOH.sub.(l) 23, producing steam (H.sub.2O.sub.(g)) and oxygen (O.sub.2(g)) 24, at the anode while NaCl.sub.(l) is not decomposed by the cell. The sodium (Na) metal 19, produced at the cathode of the cell is hermetically packaged for reuse in the hydrogen generation apparatus 10 units to produce H.sub.2(g) fuel 11. At the end of the electrolysis, the NaCl is recovered from the electrolytic cell. The plant management then decides if additional sodium (Na) metal from the NaCl is needed 25. If the plant management decides that additional Na is not needed 26, then the NaCl is mixed with seawater 27, to create concentrated brine solution 28, for use as a reactant in the hydrogen generation apparatus 10 units operating in cold climates. If the plant management decides that additional Na from the NaCl is required 29, to expand capacity in the hydrogen fuel clean energy cycle then the NaCl is sent to a Solvay plant 30, that uses calcium carbonate (CaCO.sub.3) 31, reactant to produce calcium chloride (CaCl.sub.2) 32, byproduct and sodium carbonate (Na.sub.2CO.sub.3) 33, according to the net reaction: 2NaCl+CaCO.sub.3.fwdarw.Na.sub.2CO.sub.3+CaCl.sub.2. The Na.sub.2CO.sub.3 34, is sourced economically from mining in addition to Solvay production and therefore, constitutes a cost effective means of producing large quantities of sodium (Na) metal by Na.sub.2CO.sub.3 electrolysis 35, while avoiding excess Cl.sub.2 accompanying the production of sodium (Na) metal from electrolysis of NaCl. The sodium carbonate (Na.sub.2CO.sub.3) is electrolyzed 35, at a cell operating temperature above the boiling point of sodium (Na) metal, to yield oxygen (O.sub.2(g)) 36, at the anode, and carbon (C) and sodium (Na) metal 37, at the cathode according to the following reaction:

4Na.sup.++2CO.sub.3.sup.2.fwdarw.4Na+2C+3O.sub.2Reaction 4:

The sodium (Na) metal 19, produced at the cathode of the cell is hermetically packaged for reuse in the hydrogen generation apparatus 10 units to produce H.sub.2(g) fuel 11.

[0035] Referring to FIG. 2, a depiction of the cost effective electrolytic cell designed to perform electrolysis at a temperature range between 1223.15 K (950 C.) to 1323.15 K (1050 C.) is shown consisting of a crucible 38, constructed from a refractory metal such as iron (Fe), nickel (Ni) or the nickel alloy C-276, resistant to molten salt corrosion at elevated temperatures. The crucible 38, holds a molten or fused salt charge 39, consisting of either pure sodium hydroxide (NaOH) or a mixture of sodium hydroxide (NaOH) and sea salt, the latter comprising primarily sodium chloride (NaCl). In addition, the crucible 38, can hold a charge 39, of pure sodium carbonate (Na.sub.2CO.sub.3). The crucible 38, is heated by a radiant heater 40, consisting of one or more electric heating elements 41, embedded in an insulating ceramic shell. A skirt tube 42, made from nickel or nickel alloy capable of resisting fused salt corrosion at elevated temperatures, passes through the crucible lid 43, through a ceramic collar 44, and connects the crucible 38, to a double ended cylinder 45, made from stainless steel. The ceramic collar 44, provides electrical isolation between the skirt tube 42, and the crucible lid 43. The skirt tube top end 46, is open and the skirt tube bottom end 47, is open as well. The skirt tube 42, rises midway into the double ended cylinder 45, which is located directly above the crucible lid 43. The skirt tube 42, drops nearly to the floor of the crucible 38, without contacting the bottom. A single cathode 48, electrode rod constructed from iron (Fe), nickel (Ni) or the nickel alloy C-276, enters from the top end of the double ended cylinder 45, drops through the open skirt tube top end 46, and does not extend beyond the open skirt tube bottom end 47, into the crucible 38, containing the molten salt(s). The cathode 48, electrode rod is electrically isolated from the rest of the electrolytic cell using a ceramic fitting 49, that prevents direct contact with the metallic parts of the cell. Multiple, concentrically arranged anode 50, electrode rods pass through the crucible lid 43, forming a circle around the skirt tube 42, of the electrolytic cell. The anode 50, electrode rods can be displaced linearly along the radial direction of the circular crucible lid 43, to vary the spacing between the anode 50, electrode rods and cathode 48, electrode rod. An increase in the distance between the anode 50, electrode rods and cathode 48, electrode rod results in an increase in the electrical resistance of the electrolytic cell while a decrease in distance yields a reduction in the electrical resistance of the cell. The anode 50, electrode rods are electrically isolated from other metal parts of the electrolytic cell using ceramic fittings 51. The method of operation of the electrolytic cell depends on the chemical contents of the crucible 38. If the hydrogen generation apparatus 10 shown in FIG. 1, was originally fueled with desalinated (fresh) water (H.sub.2O) and sodium (Na) metal reactants to generate hydrogen (H.sub.2) fuel 11, and sodium hydroxide (NaOH) byproduct, then the crucible 38, of the electrolytic cell will be filled with aqueous NaOH.sub.(aq) via the crucible inlet 52, and open valve 1 53. If the hydrogen generation apparatus 10 shown in FIG. 1, was originally fueled with salinated (sea) water (H.sub.2O) and sodium (Na) metal reactants to generate hydrogen (H.sub.2) fuel 11, then the crucible 38, of the electrolytic cell will be filled with a mixture of NaOH.sub.(aq) and sea salt, the latter consisting primarily of sodium chloride (NaCl). If the seawater reactant was concentrated up to 252.18 grams of sea salt solute per kilogram of seawater solution, then the crucible 38, will be filled via the crucible inlet 52, and open valve 1 53, with an aqueous mixture having an anhydrous content of 13.19% by weight sea salt and 86.81% by weight NaOH. Alternatively, the crucible 38, can be filled with aqueous Na.sub.2CO.sub.3(aq) via the crucible inlet 52, and open valve 1 53. The radiant electric heater 40, melts and raises the temperature of the crucible fused salt charge 39, to range between 1223.15 K (950 C.) to 1323.15 K (1050 C.). Steam (H.sub.2O.sub.(g)) released from the aqueous mixture of NaOH.sub.(aq) and NaCl.sub.(aq) can be vented out from the cell via the crucible outlet 54, and open valve 2 55. The steam is also vented via the double ended cylinder outlet 56, and open valve 3 57. After venting steam (H.sub.2O.sub.(g)), argon (Ar) can be introduced via the double ended cylinder inlet 58, and open valve 4 59, to purge the interior of the double ended cylinder 45, removing air and oxygen (O.sub.2) that can react with sodium (Na) vapor via the double ended cylinder outlet 56, and open valve 3 57. After purging the interior of the double ended cylinder 45, electrolysis can begin after closing the crucible inlet valve 1 53, and the double ended cylinder inlet valve 4 59, while leaving crucible outlet valve 2 55, and double ended cylinder outlet valve 3 57, open. If electrolysis is performed on pure fused NaOH.sub.(l) then the electrolytic cell voltage can be set to V.sub.CELL=1.78 V to produce sodium (Na) metal in a vapor state at the cathode 48, and steam (H.sub.2O.sub.(g)) and oxygen (O.sub.2(g)) at the anode 50. The sodium (Na) metal vapor rises up through the riser tube 42, and expands into the double ended cylinder 45, whereupon it condenses to liquid Na.sub.(l) to be transferred from the double ended cylinder 45, via the double ended cylinder outlet 56, and open valve 3 57, for packaging and reuse in the hydrogen generation apparatus 10 units shown in FIG. 1. The steam (H.sub.2O.sub.(g)) and oxygen (O.sub.2(g)) produced at the anode 50, exits the crucible 38, via the crucible outlet 54, and open valve 2 55. If electrolysis is performed on a mixture of fused NaOH.sub.(l) and NaCl.sub.(l) then the electrolytic cell voltage can be set to V.sub.CELL=3.19 V if the entire contents of the crucible 38, must be electrolyzed simultaneously, to produce sodium (Na) metal in a vapor state at the cathode 48, and steam (H.sub.2O.sub.(g)), oxygen (O.sub.2(g)) and chlorine (Cl.sub.2(g)) at the anode 50. Alternatively, the entire contents of the crucible 38, can be electrolyzed using selective electrolysis, by initially setting the electrolytic cell voltage to V.sub.CELL=1.78 V to electrolyze the fused NaOH.sub.(l), followed by an increase in voltage to V.sub.CELL=3.19 V to electrolyze the remaining fused NaCl.sub.(l). If electrolysis of the fused NaCl.sub.(l) is not required, then it can be flushed out from the crucible 38, using seawater via the crucible outlet 54, and open valve 2 55, to produce concentrated brine solution for use as a reactant in the hydrogen generation apparatus 10 units shown in FIG. 1, operating in cold climates. If electrolysis is performed on pure fused Na.sub.2CO.sub.3(l) then the electrolytic cell voltage can be set to V.sub.CELL=3.68 V to produce sodium (Na) metal in a vapor state and carbon (C) at the cathode 48, and pure oxygen (O.sub.2(g)) at the anode 50.

[0036] Referring to FIG. 3, a depiction of a variant of the cost effective electrolytic cell configured to perform electrolysis using a very high current I.sub.CELL=100,000 Amperes at a temperature range between 1223.15 K (950 C.) to 1323.15 K (1050 C.) is shown consisting of a crucible 60, constructed from a refractory metal such as iron (Fe), nickel (Ni) or the nickel alloy C-276, resistant to molten salt corrosion at elevated temperatures. The crucible 60, holds a molten or fused salt charge 61, consisting of either pure sodium hydroxide (NaOH) or a mixture of sodium hydroxide (NaOH) and sea salt, the latter comprising primarily sodium chloride (NaCl). In addition, the crucible 60, can hold a charge 61, of pure sodium carbonate (Na.sub.2CO.sub.3). The crucible 60, is heated by a radiant heater 62, consisting of one or more electric heating elements 63, embedded in an insulating ceramic shell. A skirt tube 64, made from nickel or nickel alloy capable of resisting fused salt corrosion at elevated temperatures, passes through the crucible lid 65, through a ceramic collar 66, and connects the crucible 60, to a double ended cylinder 67, made from stainless steel. The ceramic collar 66, provides electrical isolation between the skirt tube 64, and the crucible lid 65. The skirt tube top end 68, is open and skirt tube bottom end 69, is sealed. The skirt tube 64, rises midway into the double ended cylinder 67, which is located directly above the crucible lid 65. The skirt tube 64, drops nearly to the floor of the crucible 60, without contacting the bottom. A single cathode 70, electrode rod constructed from iron (Fe), nickel (Ni) or the nickel alloy C-276, enters from the top end of the double ended cylinder 67, drops through the open skirt tube top end 68, and does not contact the sealed skirt tube bottom end 69. The cathode 70, electrode rod is electrically isolated from the rest of the electrolytic cell using a ceramic fitting 71, that prevents direct contact with the metallic parts of the cell. A set of holes 72, drilled into the skirt tube sidewalls allow the molten salt electrolyte charge 61, to flow freely around the cathode 70, electrode rod shielded within the skirt tube 64. Using a skirt tube 64, with a sealed skirt tube bottom end 69, allows the entire crucible 60, to become the anode electrode of the electrolytic cell and therefore, the products of electrolysis at the anode including steam (H.sub.2O), oxygen (O.sub.2) and chlorine (Cl.sub.2) will be produced on the side wall surface 73, as well as at the floor surface 74, of the crucible 60, without risk for the anode products migrating to the cathode 70, electrode rod and reacting with Na metal to reduce the efficiency of the electrolytic cell. When it is necessary to use a large crucible 60, having a volume capable of holding a fused salt charge 61, with mass greater than 500 kg, it is possible to utilize multiple cathode electrode assemblies comprising a skirt tube 64, with a sealed skirt tube bottom end 69, double ended cylinder 67, and cathode 70, electrode rod to enable a large current I.sub.CELL=100,000 Amperes to flow in the electrolytic cell to recover large quantities of Na metal at a high rate. The electrolysis cell shown in FIG. 3 and configured to perform electrolysis using a large current I.sub.CELL=100,000 Amperes at a temperature range between 1223.15 K (950 C.) to 1323.15 K (1050 C.), operates similarly to the electrolytic cell illustrated in FIG. 2. If the hydrogen generation apparatus 10 shown in FIG. 1, was originally fueled with desalinated (fresh) water (H.sub.2O) and sodium (Na) metal reactants to generate hydrogen (H.sub.2) fuel 11, and sodium hydroxide (NaOH) byproduct, then the crucible 60, of the electrolytic cell will be filled with aqueous NaOH.sub.(aq) via the crucible inlet 75, and open valve 1 76. If the hydrogen generation apparatus 10 shown in FIG. 1, was originally fueled with salinated (sea) water (H.sub.2O) and sodium (Na) metal reactants to generate hydrogen (N.sub.2) fuel 11, then the crucible 60, of the electrolytic cell will be filled with a mixture of NaOH.sub.(aq) and sea salt, the latter consisting primarily of sodium chloride (NaCl). If the seawater reactant was concentrated up to 252.18 grams of sea salt solute per kilogram of seawater solution, then the crucible 60, will be filled via the crucible inlet 75, and open valve 1 76, with an aqueous mixture having an anhydrous content of 13.19% by weight sea salt and 86.81% by weight NaOH. Alternatively, the crucible 60, can be filled with aqueous Na.sub.2CO.sub.3(aq) via the crucible inlet 75, and open valve 1 76. The radiant electric heater 62, melts and raises the temperature of the crucible fused salt charge 61, to range between 1223.15 K (950 C.) to 1323.15 K (1050 C.). Steam (H.sub.2O.sub.(g)) released from the aqueous mixture of NaOH.sub.(aq) and NaCl.sub.(aq) can be vented out from the cell via the crucible outlet 77, and open valve 2 78. The steam is also vented via the double ended cylinder outlet 79, and open valve 3 80. After venting steam (H.sub.2O.sub.(g)), argon (Ar) can be introduced via the double ended cylinder inlet 81, and open valve 4 82, to purge the interior of the double ended cylinder 67, removing air and oxygen (O.sub.2) that can react with sodium (Na) vapor via the double ended cylinder outlet 79, and open valve 3 80. After purging the interior of the double ended cylinder 67, electrolysis can begin after closing the crucible inlet valve 1 76, and the double ended cylinder inlet valve 4 82, while leaving crucible outlet valve 2 78, and double ended cylinder outlet valve 3 80, open. If electrolysis is performed on pure fused NaOH.sub.(l) then the electrolytic cell voltage can be set to V.sub.CELL=1.78 V to produce sodium (Na) metal in a vapor state at the cathode 70, and steam (H.sub.2O.sub.(g)) and oxygen (O.sub.2(g)) at the anode 73, 74. The sodium (Na) metal vapor rises up through the riser tube 64, and expands into the double ended cylinder 67, whereupon it condenses to liquid Na.sub.(l) to be transferred from the double ended cylinder 67, via the double ended cylinder outlet 79, and open valve 3 80, for packaging and reuse in the hydrogen generation apparatus 10 units shown in FIG. 1. The steam (H.sub.2O.sub.(g)) and oxygen (O.sub.2(g)) produced at the anode 73, 74, exits the crucible 60, via the crucible outlet 77, and open valve 2 78. If electrolysis is performed on a mixture of fused NaOH.sub.(l) and NaCl.sub.(l) then the electrolytic cell voltage can be set to V.sub.CELL=3.19 V if the entire contents of the crucible 60, must be electrolyzed simultaneously, to produce sodium (Na) metal in a vapor state at the cathode 70, and steam (H.sub.2O.sub.(g)), oxygen (O.sub.2(g)) and chlorine (Cl.sub.2(g)) at the anode 73, 74. Alternatively, the entire contents of the crucible 60, can be electrolyzed using selective electrolysis, by initially setting the electrolytic cell voltage to V.sub.CELL=1.78 V to electrolyze the fused NaOH.sub.(l), followed by an increase in voltage to V.sub.CELL=3.19 V to electrolyze the remaining fused NaCl.sub.(l). If electrolysis of the fused NaCl.sub.(l) is not required, then it can be flushed out from the crucible 60, using seawater via the crucible outlet 77, and open valve 2 78, to produce concentrated brine solution for use as a reactant in the hydrogen generation apparatus 10 units shown in FIG. 1, operating in cold climates. If electrolysis is performed on pure fused Na.sub.2CO.sub.3(l) then the electrolytic cell voltage can be set to V.sub.CELL=3.68 V to produce sodium (Na) metal in a vapor state and carbon (C) at the cathode 70, and pure oxygen (O.sub.2(g)) at the anode 73, 74.

[0037] Referring to FIG. 4, a depiction of the calculated electrochemical potential of the electrolytic cell as a function of temperature is shown for sodium hydroxide (NaOH) according to Reaction 2.

4Na.sup.++4OH.sup..fwdarw.4Na+2H.sub.2O+O.sub.2Reaction 2:

Note that at the sodium hydroxide (NaOH) melting point or fusion temperature T.sub.f=594 K, applying a potential V.sub.CELL=2.34 V 83, will be sufficient to electrolyze NaOH.sub.(l). Raising the temperature of the fused NaOH.sub.(l) to the boiling point of sodium (Na) metal T.sub.b=1154.5 K, reduces the potential required for electrolyzing the fused NaOH.sub.(l) to V.sub.CELL=1.78 V 84.

[0038] Referring to FIG. 5, a depiction of the calculated electrochemical potential of the electrolytic cell as a function of temperature is shown for sodium chloride (NaCl) according to Reaction 3.

2Na.sup.++2Cl.sup..fwdarw.2Na+Cl.sub.2Reaction 3:

Note that the sodium chloride (NaCl) melting point or fusion temperature T.sub.f=1073.75 K. Applying a potential V.sub.CELL=3.19 V 85, will be sufficient to electrolyze fused NaCl.sub.(l) at the boiling point temperature of sodium (Na) metal T.sub.b=1154.5 K. From the calculations in FIG. 4 and FIG. 5, it becomes clear that selective electrolysis between the fused NaOH.sub.(l) and NaCl.sub.(l) is favored at high temperatures above the boiling point of sodium (Na) metal where the difference in the decomposition potentials between the fused NaCl.sub.(l) and NaOH.sub.(l) is given as V.sub.CELL=3.19 V1.78 V=1.41 V at the boiling point temperature of sodium (Na) metal T.sub.b=1154.5 K.

[0039] Referring to FIG. 6, a depiction of the calculated electrochemical potential of the electrolytic cell as a function of temperature is shown for sodium carbonate (Na.sub.2CO.sub.3) according to Reactions 4, 5 and 6.

4Na.sup.++2CO.sub.3.sup.2.fwdarw.4Na+2C+3O.sub.2Reaction 4:

4Na.sup.++2CO.sub.3.sup.2.fwdarw.4Na+2CO+2O.sub.2Reaction 5:

4Na.sup.++2CO.sub.3.sup.2.fwdarw.4Na+2CO.sub.2+O.sub.2Reaction 6:

Note that the sodium carbonate (Na.sub.2CO.sub.3) melting point or fusion temperature T.sub.f=1124.15 K. Applying a potential V.sub.CELL=3.68 V 86, will be sufficient to electrolyze fused Na.sub.2CO.sub.3(l) at the boiling point temperature of sodium (Na) metal T.sub.b=1154.5 K according to Reaction 4 that yields sodium (Na) metal, carbon (C) and oxygen (O.sub.2) products while suppressing the undesirable Reactions 5 and 6. The Reaction 5 occurs at V.sub.CELL=2.57 V 87, and Reaction 6 occurs at V.sub.CELL=1.63 V 88, at the boiling point temperature of sodium (Na) metal T.sub.b=1154.5 K with the undesirable evolution of carbon monoxide (CO) and/or carbon dioxide (CO.sub.2), respectively at the anode.

[0040] In summary, the principal advantages of the hydrogen fuel, sustainable, closed clean energy cycle enabled by a cost effective electrolytic cell capable of performing electrolysis on three types of molten salts individually including NaOH, NaCl, Na.sub.2CO.sub.3 or on a mixture of NaOH and NaCl, including selective electrolysis between NaOH and NaCl at temperatures ranging between 1223.15 K (950 C.) to 1323.15 K (1050 C.), well above the boiling point temperature of sodium (Na) metal, include first and foremost the possibility to supplant carbon based fossil fuels for myriad applications in ground based energy generation. The hydrogen fuel, sustainable, closed clean energy cycle of the present invention will reduce carbon dioxide (CO.sub.2) emissions and environmental pollution, leading to improved human health and economic development in the U.S.A. and worldwide. While the topic of climate change due to greenhouse gas emissions remains actively debated, it is readily evident that emissions from carbon based fossil fuel combustion have caused carbon dioxide (CO.sub.2) levels in the earth's atmosphere to exceed 0.04% (400 ppm), as confirmed by measurements made in both the northern and southern hemispheres. The rising levels of carbon dioxide (CO.sub.2) in the atmosphere, constitute a delayed yet real threat to the existence of the human species on earth, especially if vegetation can no longer sustain the rate necessary for recycling the CO.sub.2 generated by human activity. The hydrogen fuel, sustainable, closed clean energy cycle of the present invention implemented on a large scale, will function to inhibit the adverse atmospheric effects that carbon based fossil fuel use has engendered. It might also prevent the human species from becoming extinct through self-asphyxiation.