Fuel cell for downhole power systems

Abstract

One embodiment of the present invention is a fuel cell suitable for use downhole in an oil and gas well includes a fuel vessel that providing a source of fuel and an oxidant vessel providing a source of oxidant. A reaction zone comprises at least one cathode, at least one anode, and an electrolyte between each anode and cathode. A closed water vessel is connected to the reaction zone by at least one capillary flow path. The fuel cell also comprises a fuel conduit that connects the fuel vessel and the reaction zone. This fuel conduit comprises a fuel pressure control apparatus adapted to maintain a static pressure of fuel in the reaction zone. The fuel cell further comprises an oxidant conduit that connects the oxidant vessel and the reaction zone, and includes an oxidant pressure control apparatus adapted to maintain a static pressure of oxidant in the reaction zone. In addition, the fuel cell comprises electrical conductors connected to the anode and cathode and adapted to conduct electricity to an external device. In this fuel cell, there is no need for fuel, oxidant, or water to flow in a closed loop through the reaction zone.

What is claimed is:  
     
         1 . A method of supplying power to an electrical circuit of a downhole tool comprising: 
 providing a fuel cell comprising a housing, a fuel vessel, an oxidant vessel, a reaction zone and electrical connectors, wherein the fuel cell is enclosed within the housing except for the electrical connectors;    electrically connecting the fuel cell to the electrical circuit of the downhole tool;    inserting the downhole tool and fuel cell into a wellbore; and    generating electricity within the wellbore from the fuel cell and supplying at least some of the electricity to energize the electrical circuit of the downhole tool.    
     
     
         2 . The method of  claim 1 , wherein the fuel cell further comprises a battery electrically connected to the fuel cell, thus forming a hybrid power supply capable of storing a portion of the electricity generated by the fuel cell.  
     
     
         3 . The method of  claim 1 , wherein the fuel cell comprises no internal moving parts.  
     
     
         4 . The method of  claim 1 , further comprising: 
 contacting water produced within the fuel cell with metal hydride material and producing hydrogen gas.    
     
     
         5 . The method of  claim 1 , further comprising: 
 injecting the produced hydrogen gas into a fuel supply line supplying fuel to the fuel cell reaction zone.    
     
     
         6 . A power source for use in a well, comprising: 
 a solid oxide-type fuel cell.    
     
     
         7 . A method for powering a tool in a well, comprising: 
 operatively connecting a solid oxide-type fuel cell to the tool.