Method of operating an electrolyzer

Abstract

A method of operating an electrolyzer including an electrochemical cell includes detecting and/or causing a change in an electrical output of an electrolyzer power source electrically connected to an anode and a cathode of the electrochemical cell. The method includes, responsive to the detected and/or caused change in the output, feedforward controlling the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range.

What is claimed is: 
     
         1 . A method of operating an electrolyzer comprising an electrochemical cell, the method comprising:
 detecting and/or causing a change in an electrical output of an electrolyzer power source electrically connected to an anode and a cathode of the electrochemical cell, the electrochemical cell comprising
 the anode, the cathode, and a separator between the anode and cathode, 
 an anode compartment that encloses the anode, 
 a cathode compartment that encloses the cathode, 
 a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment, and 
 an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment; and 
   responsive to the detected and/or caused change in the electrical output, feedforward controlling the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range.   
     
     
         2 . The method of  claim 1 , wherein the feedforward controlling the electrolyzer comprises modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof. 
     
     
         3 . The method of  claim 1 , further comprising, responsive to the detected and/or caused change in the electrical output, feedforward controlling the electrolyzer to maintain a temperature of the separator of the electrochemical cell within a predetermined temperature range. 
     
     
         4 . The method of  claim 1 , wherein the predetermined temperature range of the separator has a difference between a maximum and minimum temperature of 0.01° C. to 10° C. 
     
     
         5 . The method of  claim 1 , wherein the predetermined temperature range of the separator has a difference between a maximum and minimum temperature 0.01° C. to 4° C. 
     
     
         6 . The method of  claim 1 , further comprising:
 detecting a change in a pressure of the cathode electrolyte output stream gas collector, a pressure of the anode electrolyte output stream gas collector, or a combination thereof; and   responsive to the detected change in pressure, feedback controlling the electrolyzer to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range.   
     
     
         7 . The method of  claim 1 , further comprising:
 detecting a change in a temperature of the anode electrolyte output stream, a temperature of the cathode electrolyte output stream, or a combination thereof; and   responsive to the detected change in temperature, feedback controlling the electrolyzer to maintain the temperature of the separator of the electrochemical cell within the predetermined temperature range.   
     
     
         8 . The method of  claim 1 , further comprising performing a method using a multiplicity of the electrochemical cells in the electrolyzer. 
     
     
         9 . The method of  claim 1 , wherein the feedforward controlling is performed by a programmable logic controller (PLC), a distributed control system (DCS), or a combination thereof. 
     
     
         10 . The method of  claim 1 , wherein the feedforward controlling comprises determining the current density of the electrochemical cell from the determined and/or caused electrical output, and using a relationship between current density and a temperature of the separator and/or a relationship between current density and produced gas pressure of the electrochemical cell to determine to what extent to perform modifying a temperature of the cathode electrolyte input stream, modifying a flow rate of the cathode electrolyte input stream, modifying a temperature of the anode electrolyte input stream, modifying a flow rate of the anode electrolyte input stream, modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof, in order to maintain the pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within the predetermined respective pressure range. 
     
     
         11 . The method of  claim 6 , wherein the feedforward controlling is performed at a rate that is greater than a rate at which the feedback controlling is performed. 
     
     
         12 . The method of  claim 6 , wherein the feedback controlling is performed by a proportional-integral-derivative (PID) controller. 
     
     
         13 . The method of  claim 1 , wherein the predetermined pressure range of the cathode and anode electrolyte output stream gas collectors independently have a difference between a maximum and minimum pressure of 0.001 psi to 1 psi. 
     
     
         14 . The method of  claim 1 , wherein the predetermined pressure range of the cathode and anode electrolyte output stream gas collectors have a difference between a maximum and minimum pressure of 0.001 psi to 0.3 psi. 
     
     
         15 . The method of  claim 1 , wherein the separator comprises a porous membrane (e.g., a microporous membrane or a nanoporous membrane), an ion-exchange membrane, an ion-solvating membrane, or a diaphragm. 
     
     
         16 . The method of  claim 1 , wherein the feedforward controlling the electrolyzer and the feedback controlling the electrolyzer comprise modifying a pressure valve configuration on the cathode electrolyte output stream gas collector, modifying a pressure valve configuration on the anode electrolyte output stream gas collector, or a combination thereof. 
     
     
         17 . The method of  claim 16 , wherein the modifying of the pressure valve configuration on the cathode or anode electrolyte output stream gas collector comprises opening, closing, or setting a new pressure valve value of one or more valves that are fluidly connected to the respective cathode or anode electrolyte output stream gas collector. 
     
     
         18 . The method of  claim 1 , wherein the electrolyzer power source comprises solar power, wind power, a battery, geothermal power, hydroelectric power, tidal power, public utility grid power, or a combination thereof. 
     
     
         19 . An electrolyzer system comprising:
 an electrochemical cell in an electrolyzer, the electrochemical cell comprising
 an anode, a cathode, and a separator between the anode and cathode, 
 an anode compartment that encloses the anode, 
 a cathode compartment that encloses the cathode, 
 a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment, and 
 an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment; 
   an optional detector that is configured to detect a change in an electrical output of an electrolyzer power source that is electrically connected to the anode and the cathode of the electrochemical cell; and   a feedforward control system that, responsive to the detected change in output or a caused change in output, is configured to feedforward control the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range.   
     
     
         20 . A tangible non-transitory computer readable medium, the computer readable medium storing one or more computer applications that, when executed by one or more processors, causes the one or more processors to perform a method comprising:
 determining whether a change is detected in an electrical output of an electrolyzer power source electrically connected to an anode and a cathode of an electrochemical cell, the electrochemical cell comprising
 the anode, the cathode, and a separator between the anode and cathode, 
 an anode compartment that encloses the anode, 
 a cathode compartment that encloses the cathode, 
 a cathode electrolyte input stream that flows to the cathode compartment, and a cathode electrolyte output stream gas collector fluidly connected to a cathode electrolyte output stream that exits the cathode compartment, and 
 an anode electrolyte input stream that flows to the anode compartment, and an anode electrolyte output stream gas collector fluidly connected to an anode electrolyte output stream that exits the anode compartment; 
   responsive to determining that a change is detected in the electrical output of the electrolyzer power source, feedforward controlling the electrolyzer to maintain a pressure of the cathode electrolyte output stream gas collector and/or the anode electrolyte output stream gas collector within a predetermined respective pressure range.