Use of Ammonia as Source of Hydrogen Fuel and as a Getter for Air-CO2 in Alkaline Membrane Fuel Cells

Abstract

Embodiments of the invention provide an ammonia operated fuel cell system including an alkaline membrane fuel cell (AMFC) having an anode, and an ammonia thermal cracker including a combustion chamber, the cracker being in gas communication with an ammonia source, and configured to provide a supply of H 2 directly to the AMFC anode.

What is claimed is: 
     
         1 . An ammonia operated fuel cell system comprising:
 an alkaline membrane fuel cell (AMFC) having an anode;   an ammonia thermal cracker including a combustion chamber, the cracker being in gas communication with an ammonia source, and configured to provide a supply of H 2  directly to the AMFC anode.   
     
     
         2 . The ammonia operated fuel cell system of  claim 1  wherein exhaust from the anode of the AMFC is fed into the combustion chamber of the cracker. 
     
     
         3 . The ammonia operated fuel cell system of  claim 1  wherein the cracker is configured to produce an output of substantially 75% Hydrogen and 25% Nitrogen. 
     
     
         4 . The ammonia operated fuel cell system of  claim 1  further comprising a flow channel configured to provide a substantially uniform concentration of H 2  to substantially all parts of an active area of the AMFC. 
     
     
         5 . The ammonia operated fuel cell system of  claim 4  wherein the flow channel includes a spiral in a first rotational sense between an inlet and a center and a spiral in a second rotational sense between the center and the outlet. 
     
     
         6 . The ammonia operated fuel cell system of  claim 1  wherein a cathode of the AMFC is in gas communication with the ammonia source. 
     
     
         7 . The ammonia operated fuel cell system of  claim 6  wherein an air supply to the cathode of the AMFC is configured to receive a bleed of ammonia from the ammonia source. 
     
     
         8 . The ammonia operated fuel cell system of  claim 1  wherein an ammonia supply to a cathode of the AMFC is configured to getter CO 2  from the air supply. 
     
     
         9 . The ammonia operated fuel cell system of  claim 1  wherein an exhaust from a cathode of the AMFC is fed into the combustion chamber of the ammonia cracker. 
     
     
         10 . The ammonia operated fuel cell system of  claim 1  wherein the cracker output also contains significant levels of ammonia residues. 
     
     
         11 . The ammonia operated fuel cell of  claim 10  wherein the ammonia residues concentration of the cracker output are from about 1 ppm to about 20,000 ppm. 
     
     
         12 . The ammonia operated fuel cell system of  claim 1  where the thermal cracker is heated substantially by combustion of ammonia.