Conventional chemical batteries have a number of disadvantages. One disadvantage is that they have limited capacity with respect to their energy density. This capacity limitation impacts the ability of current chemical batteries to operate under continuous load. Even rechargeable batteries are often limited to 4-5 hours of continuous usage. Another disadvantage is that they have a relatively short shelf-life, often less than 3 to 5 years. A final disadvantage is that many modern batteries include harsh or toxic chemicals that pose long-term environmental hazards.
Fuel cell devices can deliver electrical energy without some of the disadvantages of conventional batteries. However, many fuel cell configurations have drawbacks of their own. For instance, some designs utilize a fuel supply that is external to the device. The proton exchange membrane fuel cell (PEMFC) uses oxygen and hydrogen. The oxygen is typically taken from the air but the hydrogen is typically supplied as a clean gas from an external hydrogen supply, such as a storage tank or other external source. Although such fuel cells may be acceptable for providing electrical energy to stationary loads, these configurations are not currently considered appropriate for movable or portable loads found in consumer electronic devices. Additionally, the very presence of an external fuel supply renders them impractical (perhaps even unsafe) for use in applications involving remote devices, such as safety devices or alarm sensors situated within a building.
Recent developments have eliminated the need for an external fuel source by providing an internal fuel which stores hydrogen and releases the hydrogen via a chemical reaction. Such fuels include solid materials such as Al or NaBH4, which in the presence of water react to produce hydrogen.
One of the problems with using fuel cells containing a solid fuel source is the inability to recharge the depleted solid fuel. The following describes devices and methods for recharging the solid fuel used to generate hydrogen in a hydrogen consuming device such as a hydrogen fuel cell.
Disclosed herein are the methods and apparatus of the invention. This invention is not to be regarded as limited to any particular section disclosed herein.
A method of recharging an M(BH4)y fuel by converting M(BO2)y to M(BH4)y, wherein M(BO2)y is a byproduct of the reaction of M(BH4)y fuel with H2O to produce hydrogen for a hydrogen consuming device and wherein M is cationic metal ion and y is an integer having the same value as the charge on M is described. The method comprising reacting the M(BO2)y with Al and hydrogen to produce M(BH4)y and Al2O3. The method further comprises supplying the Al by electrolytically converting Al2O3 to Al and oxygen. The method further comprises supplying the hydrogen from a hydrogen supply, wherein the hydrogen supply is an electrolytic cell which converts water into hydrogen and oxygen. The method further comprises obtaining the M(BO2)y from a fuel cartridge of the hydrogen consuming device. The method further comprises delivering the M(BH4)y to a fuel cartridge of the hydrogen consuming device. M can be selected from the group consisting of Li, Na, Mg, and K. The electrolytic cell may be a reverse fuel cell.
Additional metals which can react with M(BO2)y to produce M(BH4)y include Na and Mg. Alternatively a mixture or alloy of Na and Mg or Na and Al could be used as a fuel source for the hydrogen consuming device and the method can be adapted for recharging the mixture or alloy of Na and Mg or Na and Al.
The method further comprises transporting the spent fuel from the hydrogen consuming device and delivering the recycled fuel to the hydrogen consuming device. In one example the method comprises using a carrier liquid for transporting the spent fuel and the recycled fuel.
The apparatus comprises a housing for mounting a fuel cartridge of the hydrogen consuming device, a reaction vessel for converting the spent fuel to the fuel and a hydrogen supply for supplying hydrogen reactant to the reaction vessel. The apparatus further comprises a transport mechanism for transporting the spent fuel from the hydrogen consuming device and delivering the recycled fuel to the hydrogen consuming device. In one example, the transport mechanism comprises a pump for running a carrier liquid through a fuel cartridge of the hydrogen consuming device. The carrier liquid which forms a slurry with the spent fuel, residual fuel and catalyst and transports the spent fuel, residual fuel and catalyst to a separator present within the charger. The carrier liquid is then removed from the separator and the spent fuel present in the separator is introduced into a reaction vessel for conversion to fuel. Following conversion, the fuel put back into the separator and the carrier liquid is used to transport the fuel back to the fuel cartridge.
As used herein, the singular form “a”, “an”, and “the” includes plural references unless indicated otherwise. For example, “a” reaction includes one or more reactions. For example “an” inlet includes one or more inlets.
The described devices and methods are for recharging fuels used to generate hydrogen in a hydrogen consuming device such as a hydrogen fuel cell. Thus, when the fuel in the hydrogen consuming device gets depleted, the hydrogen fuel consuming device may be recharged by providing a source of hydrogen and heat as described below.
A number of solid fuels can be used to generate hydrogen for a hydrogen consuming device. For instance, members of the alkali metal group of the Mendeleev Chart, such as sodium, and various other metals, such as aluminum and magnesium, readily react with water in alkaline solution to produce hydrogen gas. An example of a balanced equation for the generation of hydrogen from aluminum is given as:
Al+NaOH+H2O→NaAlO2+1.5H2⇑+Heat
Additionally, hydride salts of metals, alkali metals, and alkaline earth metals, and complex salts of metals, alkali metals, and alkaline earth metals, react with water to produce hydrogen. An example of a balanced equation for the reaction of a metal hydride with water to produce hydrogen is given as:
MgH4+2H2O→Mg(OH)2+3H2⇑+Heat
Still another class of solid fuels comprises borohydride salts of alkali metals, alkaline earth metals, ammonium, and alkyl ammonium and complex salts thereof. One such member is sodium borohydride. A balanced equation for the generation of hydrogen from sodium borohydride is given as:
NaBH4+2H2O→NaBO2+4H2⇑+Heat
In addition to sodium, other alkali metals suitable as hydrogen-generating fuels include lithium, potassium, and rubidium. Other metals in addition to aluminum suitable for use in hydrogen-generating fuels include magnesium and zinc. Examples of candidates from the group of hydride salts of metals, alkali metals, and alkaline earth metals, and complex salts thereof, in addition to the aforementioned magnesium hydride, include NaAlH4, LiAlH4, KAlH4, NaGaH4, LiGaH4, KGaH4, Mg(AlH4)2, Li3AlH6, Na3AlH6, and Mg2NiH4, and their mixtures. Finally, in addition to sodium borohydride, other suitable borohydride salts of alkali metals, alkaline earth metals, ammonium, and alkyl ammonium and complex salts thereof include LiBH4, KBH4, Mg(BH4)2, Ca(BH4)2, NH4BH4, and (CH3)4NBH4, and their mixtures.
Additionally, the hydrogen-producing solid fuel may further comprise catalysts or catalyst precursors. Materials that are useful as these optional catalysts include transition metals, transition metal borides, and alloys and mixtures of these materials. Suitable transition metal catalysts are listed in U.S. Pat. No. 5,804,329, to Amendola, the entirety of which is incorporated herein by reference. Catalysts containing Group IB to Group VIIIB metals, such as transition metals of the copper group, zinc group, scandium group, titanium group, vanadium group, chromium group, manganese group, iron group, cobalt group, and nickel group are suitable in various configurations. Such catalysts lower the activation energy of the reaction of borohydrides with water to produce hydrogen. Specific examples of suitable transition metal elements include ruthenium, iron, cobalt, nickel, copper, manganese, rhodium, rhenium, platinum, palladium, chromium, silver, osmium, iridium, their compounds, their alloys, and their mixtures.
A number of chemical schemes exist in which a set of coupled chemical reactions can be used to recycle a fuel used to produce hydrogen gas. Examples of reaction schemes which can be used to recharge mixtures or alloys of Na and Mg or Na and Al, and M(BH4)y solid fuels are shown below.
For Na/Mg, the hydrogen production reaction is given as:
2Na+2Mg+4H2O→2NaOH+2MgO+3H2+Heat
The reaction products of the Na/Mg hydrogen-producing solid fuel are NaOH and MgO as shown above. The NaOH and the MgO can be converted back into Na and Mg through a series of coupled chemical reactions. The NaOH and MgO are first converted into NaCl and MgCl2 by the balanced reaction:
2 NaOH+2 MgO+6 HCl+Heat→2 NaCl+2 MgCl2+4 H2O
The NaCl and MgCl2 can then be converted to Cl2 and Mg/Na by the reaction:
2 NaCl+2 MgCl2+Heat→3 Cl2+2 Mg+2 Na
The Cl2 can then be reacted with H2 to produce HCl by the reaction:
3 Cl2+3 H2→6 HCl+Heat
The HCl can then be reused to convert additional NaOH and MgO into Mg and Na.
The overall reaction is:
The byproduct of the overall reaction is H2O, which can further be electrolytically converted to hydrogen and oxygen. The resulting hydrogen can then be used in the above reaction scheme to convert the Cl2 into HCl.
For Na/Al, the hydrogen production reaction is given as
Na+Al+2 H2O→NaAlO2+2 H2+Heat
The reaction product of the Na/Al hydrogen-producing solid fuel is NaAlO2 as shown above. The NaAlO2 can be converted back into Na and Al through a series of coupled chemical reactions. The NaAlO2 is first converted into NaCl and AlCl3 by the reaction:
NaAlO2+4 HCl+Heat→NaCl+AlCl3+2 H2O
The NaCl and AlCl3 can be converted to Cl2, Al, and Na by the reaction:
AlCl3+NaCl+Heat→2 Cl2+Al+Na
The Cl2 can then be reacted with H2 to produce HCl by the reaction:
2 Cl2+2H2→4HCl+Heat
The HCl can then be reused to convert additional NaAlO2 to Al and Na.
The overall reaction is:
The byproduct of the overall reaction is H2O, which can further be electrolytically converted to hydrogen and oxygen. The resulting hydrogen can then be used in the above reaction scheme to convert the Cl2 into HCl.
For M(BH4)y, the hydrogen production reaction is given as:
1 M(BH4)y+2y H2O→4y H2+1 M(BO2)y+Heat
The reaction product of the M(BH4)y hydrogen-producing solid fuel is M(BO2)y as shown above. The M(BO2)y can be converted back into M(BH4)y by reacting the M(BO2)y with a metal and hydrogen gas. Examples of metals that can be used include Al, Mg, and Na. The balanced reactions for converting M(BO2)y to M(BH4)y using Al, Mg, or Na are given as:
3 M(BO2)y+4y H2+4y Al→2y Al2O3+2 M(BH4)y
1 M(BO2)y+2y H2+2y Mg→2y MgO+1 M(BH4)y
1 M(BO2)y+(2y+1) H2+2 Na→2 NaOH+1 M(BH4)y
The oxidized metal reaction products of the above reaction, Al2O3, MgO, and NaOH, can then be converted back to the reduced metal (i.e. Al, Mg, and Na) and reused to convert M(BO2)y to M(BH4)y.
The Al2O3 can be converted directly into Al and O2 by the reaction:
2 Al2O3→4 Al+3 O2
The byproduct of the reaction is O2 which can react with hydrogen to form water or be released into the atmosphere.
The MgO and NaOH can be converted to Mg and Na through a series of coupled chemical reactions.
The MgO is first converted into MgCl2 by the reaction:
1 MgO+2 HCl+Heat→MgCl2+1 H2O
The MgCl2 is then converted to Mg and Cl2 by the reaction:
1 MgCl2+Heat→1 Mg+1 Cl2
The Cl2 is then reacted with H2 to produce HCl by the reaction:
2Cl2+2 H2→4 HCl+Heat
The HCl can then be reused to convert additional MgO to Mg, as shown above. The overall reaction for converting MgO to Mg is:
The byproduct of the reaction is H2O.
The NaOH is first converted into NaCl by the balanced reaction:
2 NaOH+2 HCl→2 NaCl+2 H2O+HEAT
The NaCl is then converted to Na and Cl2 by the reaction:
2 NaCl→2 Na+Cl2
The Cl2 is then reacted with H2 to produce HCl, by the reaction:
Cl2+H2→2 HCl+Heat
The HCl can then be reused to convert additional NaOH as shown above.
The overall reaction for converting NaOH to Na is:
The byproduct of the reaction is H2O.
A charger is described below which is configured to recharge a fuel used to produce hydrogen for a hydrogen consuming device such as a hydrogen fuel cell. The charger can be configured such that the reactants which react with the spent fuel, in the process of recharging the fuel, can be self contained within the charger and will not require replenishing after multiple recharge cycles. Instead the reactants are recycled through electrolysis or by reacting with hydrogen or a combination of the two. Alternatively, some or all of the reactants can be supplied to the charger after every recharge cycle.
While the device below is described in terms of NaB and NaBO2, the description applies to devices that utilize M(BH4)y to produce M(BO2)y and that utilize the reaction schemes discussed above to regenerate the spent fuel.
Charger 100 contains a housing 104 for attaching a fuel cartridge 102. Fuel cartridge 102 may or may not be attached to a hydrogen consuming device prior to attachment to the charger 100. Whether or not fuel cartridge 102 is attached to the hydrogen consuming can depend on whether or not the fuel cartridge 102 is removable from the hydrogen consuming device. Alternatively, the charger and the hydrogen consuming device may be incorporated into a single device.
Housing 104 may contain additional elements, such as flow channels for transferring NaBO2 to the charger and for transferring NaBH4 to fuel cartridge 102. The configuration of housing 104 and the additional elements depends on the mechanisms by which NaBH4 and NaBO2 are transferred to and from cartridge 102. The NaBO2 contained within cartridge 102 is transferred to a reaction vessel 106 contained within charger 100. Reaction vessel 106 is configured to convert NaBO2 to NaBH4 and electrolytically convert Al2O3 to Al and O2. Additionally, the charger contains a hydrogen supply 108 which supplies hydrogen that is used in the conversion of NaBO2 to NaBH4. In one system, as depicted in
Charger 100 further contains a power supply 112 which can be plugged into a wall socket to supply power to charger 100.
In one system, depicted in
As discussed above, reaction vessel 106 is configured for two reactions. One reaction is between NaBO2, H2 and Al to produce NaBH4. The second reaction, conversion of Al2O3 to Al and O2, is an electrolysis reaction and requires that reaction vessel 106 be configured as an electrolytic cell.
In the second step, shown in
In the third step, as depicted in
In the fourth step, depicted in
In one system, the NaBH4, the catalyst, and the NaBO2 reaction product are contained in individual capsules 402 fixed within cartridge 102, as shown in
One mechanism for delivering NaBO2 from the fuel cartridge to the reaction vessel and for delivering the NaBH4 from reaction vessel to the fuel cartridge 102 is shown in
Each of the capsules have two flow channels 504 and 506 for introducing a carrier liquid used to transport the NaBO2 out of the capsule and transport NaBH4 into the capsules. Carrier liquids, that are suitable to transport NaBH4 and NaBO2, include mineral oil and secondary alcohols that do not react with NaBO2 or NaBH4. Each of the flow channels 504 are connected to a central flow channel 508 and each of the flow channels 506 are connected to a central flow channel 510. The central flow channels 510 and 508 interface with charger 100. Preferably, the charger interface has two fittings (not shown) with a diameter of less than about 0.1-100 mm or has a signal coaxial fitting (not shown) with a diameter of less than about 0.1-100 mm. Alternatively, the diameters of the fittings can be changed according to different applications. Each of the flow channels, 504 and 506, have a valve 534, which controls the opening and the closing of the flow channels.
To remove NaBO2 from the cartridge a pump 512, in fluid communication with a liquid carrier reservoir 514 containing the carrier liquid, pumps the carrier liquid through flow channel 538. The carrier liquid enters the charger through central flow channel 510 and into one of the individual capsules through flow channel 506. The capsule through which the carrier liquid is being pumped has its valves 534 in the open position. The carrier liquid forms a slurry with NaBO2, catalyst and any NaBH4 present in the capsule. The slurry then exits the individual capsules through flow channel 504, exits fuel cartridge 102 through central flow channel 508, enters flow channel 536 and enters a separator 516 present within the charger 100. The direction of flow during the process of removing NaBO2 from the capsules is depicted by arrow 530. Separator 516 is attached to reaction vessel 106 through a second flow channel 204. Separator 516 has a valve 526 that prevents the passage of carrier liquid to reaction vessel 106 and is closed when the carrier liquid is present in the separator 516. The separator has two flow channels 518 and 520. The slurry containing NaBO2 enters separator 516 through flow channel 518. The combination of pump 512, reservoir 514, separator 516, and any one of the capsules 502 form a closed loop through which the carrier liquid can flow.
Separator 516 has a filter 522 which allows for the passage of the carrier liquid through flow channel 520 while preventing the NaBO2, NaBH4, and catalyst from passing through the separator into the liquid carrier reservoir 514. Once the carrier liquid has passed filter 522, the carrier liquid exits separator 516 through flow valve 520 and enters liquid reservoir 514. The carrier liquid that passes through separator 516 can be further pumped into capsules 502 and used to extract additional NaBO2 from capsules 502.
Following the transfer of NaBO2 from the capsules to the separator, pump 512 removes the remaining mineral oil from separator 516 and transports the carrier liquid back to reservoir 514. Removal of the carrier liquid from separator 516 is achieved by closing valves 534 and evacuating the carrier liquid from the separator 516. Pump 512 creates a vacuum that causes the carrier liquid to withdraw from separator 516 to reservoir 514.
The separator is surrounded by a heating coil 524, and after removing the carrier liquid from the separator, the heating coil is activated and heats the separator 516 to a temperature of about 57° C.-270° C., which liquefies the NaBO2. As discussed above the NaBO2 is a hydrate. Following liquefaction of the NaBO2, valve 526 is set to open and the liquid NaBO2 is transferred to reaction vessel 106 through the flow channel 204. In this example, separator 516 is situated above reaction vessel 106 so that liquid NaBO2 can drain into reaction vessel 106. Additionally, the NaBO2 may get drawn into reaction vessel 106 by introducing a vacuum through flow channel 202 or may get pushed into reaction vessel 106 by pumping H2 into the separator and increasing the pressure. The catalyst and any residual NaBH4 that remain in the separator are prevented from entering the reaction vessel by a filter (not shown) in valve 526.
The NaBO2 is then converted to NaBH4 as discussed above. Prior to transferring the NaBH4 from reaction vessel 106 to separator 516, the valves 534 on one of the capsules are set to open. Pump 512 then pumps carrier liquid through the separator, and through the open capsule. The carrier liquid is pumped in the opposite direction as depicted by arrow 528. Valve 526 on the separator 516 is then set to open. The hydrogen pressure in flow channel 204 prevents the carrier liquid from entering reaction vessel 106. The pressure from the hydrogen in the reaction vessel 106 causes injection of the NaBH4 into separator 516 through flow channel 204. Additionally, as discussed above, the increased hydrogen pressure prevents the NaBH4 from decomposing.
The NaBH4 injected as droplets into the separator 516 makes contact with the carrier liquid, cools, solidifies and forms a slurry with the carrier liquid. The slurry may also contain the catalyst and residual NaBH4 that was present in separator 516. The cooling of NaBH4 by the carrier liquid and the formation of a slurry allows for the formation and transportation of small particles of NaBH4 as opposed to a solid mass, which would form if the liquid NaBH4 was directly transported to the capsules 402 without the use of the carrier liquid. It is preferable for the NaBH4 to be in the form of a powder because a powder exposes a larger surface area of NaBH4 and enhances accessibility to the fuel by water.
The slurry containing the NaBH4 is then pumped from separator 516 to one of the capsules 502. The slurry leaves the separator through flow channel 518 and enters the capsule through flow channel 504 via flow channel 536 and central flow channel 508. Once the NaBH4 has been transferred to the capsules 502, the valve on flow channel 504 is closed and the carrier liquid remaining in the capsules is drawn out and transferred to reservoir 514. The capsules contain a filter 532, located near flow channels 506, which allows the passage of the carrier liquid through the capsules but prevents the NaBH4 and catalyst from escaping the capsules when being transported to the capsules 402 from the separator. Following removal of the carrier liquid from the capsules the recharging of the NaBH4 fuel is complete.
Another system for transferring the NaBO2 from cartridge 102 is depicted in
In
In another system, the conversion of NaBO2 to NaBH4 can be separately performed in two reaction vessels as depicted in
In another system each of the reaction vessels 902 and 904 may be configured to be dual purpose reaction vessels in a manner similar to reaction vessel 106 (
An example of an electrolytic cell hydrogen supply 1000 (
Additional fuels such as alloys or mixtures of Na and Mg or Na and Al alloys, as well as other borohydrides, of the formula M(BH4)y, can be used to produce hydrogen and recharged in similarly constructed chargers. Additionally metals reactants, such as Mg or Na, can be used to reduce M(BO2)y to M(BH4)y.
In
In
Additional applications for the charger include recharging batteries used for telecommunication devices such as cellular phones, portable electronic devices such as lap tops, digital music players, personal digital assistants, and global positioning systems, backup power supplies, remote sensors, and closed circuit cameras. The charger can be configured for batteries used for any residential, industrial or commercial electronic device. The charger can also be configured to recharge batteries used to power a mechanical engine, such as in an automobile. Battery components can be adjusted so as to provide the required voltage, power, and current handling capabilities for each application. For example, electrical components such resistors, diodes, capacitors, and transistors may be modified to achieve the proper electrical configuration for the desired application.
The electronics and electrical circuitry required for interfacing a fuel cell battery with an electronic device are described in U.S. Pat. No. 7,005,206 and U.S. Patent Application No. 2004175598, which are herby incorporated by reference. Thus, one of ordinary skill in the art could replace the fuel cell battery of the above reference with a battery configured to be recharged by the charger as disclosed in the current application.
Additional applications for the charger include recharging batteries used for transportation, backup power or any other application requiring battery power.
A number of charger configurations have been disclosed for recharging fuel used to generate hydrogen for a hydrogen consuming device. Various modifications of those described may be made without departing from the scope or spirit of the disclosure. Those examples should not be construed as limiting scope of the charge otherwise described above.
This application claims the benefit of U.S. provisional application Ser. No. 60/810,425, filed Jun. 1, 2006, which is hereby incorporated by reference in its entirety as if put forth in full below.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US07/12984 | 6/1/2007 | WO | 00 | 6/5/2009 |
Number | Date | Country | |
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60810425 | Jun 2006 | US |