Energy-Harvesting Reactor Based on Diffusion of Aluminum in Gallium

Abstract

Aluminum may be used as a fuel source to power small vehicles, unmanned vehicles or underwater vehicles, other small robotics, backup or regular underwater power sources (e.g., for oil rigs), or as an emergency power source in flooded or disaster areas. Reactors are described that harvest energy produced by the exothermic oxidative reaction of aluminum or an aluminum alloy with water, with the assistance of liquid gallium as a depassivating agent.

What is claimed is: 
     
         1 . An electrochemical reactor for use in an energy storage system comprising:
 a housing configured to continuously circulate fluid in a unidirectional loop, the fluid comprising liquid gallium;   an aluminum port configured to introduce aluminum or an aluminum alloy in a solid phase into the housing;   a water injection port configured to introduce water into the housing;   a thermal energy harvester coupled to the housing and configured to convert heat into electrical energy; and   a waste separation system in fluid communication with the housing and configured to remove aluminum hydroxide from the fluid.   
     
     
         2 . The electrochemical reactor of  claim 1 , wherein the water injection port is positioned downstream from the aluminum port. 
     
     
         3 . The electrochemical reactor of  claim 2 , further comprising a pump configured to continuously recirculate the fluid, wherein the pump is selected from the group consisting of a diaphragm pump, an electromagnetic pump, a magnetic drive pump, a positive displacement pump, a velocity pump, a centrifugal pump, and combinations thereof. 
     
     
         4 . The electrochemical reactor of  claim 1 , wherein the waste separation system includes a physical separation system selected from the group consisting of a centrifuge, baffles, annular piping, a separator using coulombic forces or electric fields, and combinations thereof. 
     
     
         5 . The electrochemical reactor of  claim 1 , wherein the waste separation system includes a chemical separation system having a chemical agent or additive. 
     
     
         6 . The electrochemical reactor of  claim 1 , further comprising:
 a vent configured to allow hydrogen to be released from within the housing.   
     
     
         7 . The electrochemical reactor of  claim 6 , wherein the vent includes a membrane configured to keep the fluid within the housing and to allow the hydrogen to be released from the housing. 
     
     
         8 . The electrochemical reactor of  claim 6 , further comprising:
 a hydrogen fuel cell coupled to the vent and configured to use the hydrogen in the hydrogen fuel cell.   
     
     
         9 . The electrochemical reactor of  claim 1 , wherein the water injection port further includes a water pump configured to introduce the water into the housing. 
     
     
         10 . The electrochemical reactor of  claim 1 , wherein the thermal energy harvester operates using an engine selected from the group consisting of an organic Rankine cycle engine, a Rankine cycle engine, organic Brayton engine, Brayton cycle engine, supercritical CO 2  Brayton engine, a Stirling cycle engine, and combinations thereof. 
     
     
         11 . A method of using an electrochemical reactor, the method comprising:
 providing a fluid comprising liquid gallium in a housing, the housing forming a loop and configured to continuously circulate the fluid in one direction within the loop;   introducing aluminum or an aluminum alloy in a solid phase into the fluid at a first location in the housing so that the aluminum or the aluminum alloy substantially dissolves in the fluid;   introducing water into the fluid at a second location in the housing, wherein the first location is upstream from the second location producing an aluminum oxide, hydrogen and heat;   converting the heat into electrical energy using a thermal energy harvester coupled to the housing;   removing the aluminum oxide from the fluid; and   recirculating the fluid in the housing upstream from the first location.   
     
     
         12 . The method of  claim 11 , wherein the aluminum alloy is an aluminum-gallium alloy. 
     
     
         13 . The method of  claim 11 , wherein converting the heat into electrical energy occurs at a third location and removing the aluminum oxide from the fluid occurs at a fourth location, wherein the third location is upstream from the fourth location. 
     
     
         14 . The method of  claim 11 , wherein removing the aluminum oxide includes using a physical separation system. 
     
     
         15 . The method of  claim 14 , wherein the physical separation system includes a centrifuge, a positive displacement pump, a velocity pump, a centrifugal pump, or combinations thereof. 
     
     
         16 . The method of  claim 11 , wherein removing the aluminum oxide includes using a chemical separation system configured to substantially remove the aluminum oxide from the fluid. 
     
     
         17 . The method of  claim 11 , wherein the aluminum or the aluminum alloy is introduced as a wire, a foil, a block, pellets, or a combination thereof. 
     
     
         18 . The method of  claim 11 , further comprising introducing an additive to the fluid so as to facilitate the dissolving of the aluminum or the aluminum alloy in the fluid. 
     
     
         19 . A method of using a chemical reactor, the method comprising:
 providing a fluid comprising liquid gallium in a housing, the housing forming a loop and configured to continuously circulate the fluid in one direction within the loop;   introducing aluminum or an aluminum alloy in a solid phase into the fluid in the housing, whereby a liquid aluminum/gallium alloy is produced at a first location within the loop; and   introducing water into the fluid in the housing, whereby an aluminum oxide, hydrogen and heat are produced at a second location within the loop, wherein the first location is in fluid communication with, and separate from, the second location.   
     
     
         20 . A method of using a chemical reactor, the method comprising:
 circulating a fluid comprising liquid gallium within a housing, wherein in a first sector of the housing, the fluid comprises substantially liquid gallium;   introducing aluminum or an aluminum alloy in a solid phase into the fluid whereby in a second sector of the housing, the fluid comprises substantially a liquid aluminum/gallium alloy; and   introducing water into the fluid in the housing whereby in a third sector of the housing, the fluid comprises substantially a mixture of gallium, an aluminum oxide, and hydrogen.