Systems and methods to monitor membranes of an electrolysis system

Abstract

An electrolysis system includes an electrolyzer cell stack and a pinhole monitoring system. The electrolyzer cell stack uses water and electricity to produce a hydrogen product gas and an oxygen product gas. The pinhole monitoring system is configured to monitor membranes included in the electrolyzer cell stack to detect a pinhole formed therein.

What is claimed is: 
     
         1 . An electrolysis system comprising:
 an electrolyzer cell stack configured to use water and electricity to produce a hydrogen product gas and an oxygen product gas, the electrolyzer cell stack comprising:
 a first cell having a first anode, a first cathode spaced apart from the first anode, and a first membrane arranged between the first anode and the first cathode; and 
 a second cell having a second anode, a second cathode spaced apart from the second anode, and a second membrane arranged between the second anode and the second cathode; and 
   a pinhole monitoring system configured to monitor the first membrane and the second membrane to detect a pinhole formed therein, the pinhole monitoring system including a controller configured to:
 hold a current density of the electrolyzer cell stack at a first current density for a predetermined time period; 
 decrease the current density of the electrolyzer cell stack to a second current density in response to holding the current density at the first current density for the predetermined time period; and 
 determine that:
 the first membrane has the pinhole formed therein in response to a first voltage of the first cell being less than a voltage threshold while in the second current density, and/or 
 the second membrane has the pinhole formed therein in response to a second voltage of the second cell being less than the voltage threshold while in the second current density. 
 
   
     
     
         2 . The electrolysis system of  claim 1 , wherein the first current density is about 1.0 to about 2.0 A/cm 2 . 
     
     
         3 . The electrolysis system of  claim 2 , wherein the second current density is about 5 mA/cm 2 . 
     
     
         4 . The electrolysis system of  claim 1 , wherein the voltage threshold is about 0.8 V to about 1.4 V. 
     
     
         5 . The electrolysis system of  claim 1 , wherein the controller is configured to decrease the current density of the electrolyzer cell stack to a third current density less than the second current density in response to:
 the first voltage of the first cell being greater than the voltage threshold while in the second current density, or   the second voltage of the second cell being greater than the voltage threshold while in the second current density.   
     
     
         6 . The electrolysis system of  claim 5 , wherein the controller is configured to determine that:
 the first membrane has the pinhole formed therein in response to a third voltage of the first cell being less than the voltage threshold while in the third current density, and/or   the second membrane has the pinhole formed therein in response to a fourth voltage of the second cell being less than the voltage threshold while in the third current density.   
     
     
         7 . The electrolysis system of  claim 1 , wherein the controller is configured to reverse a flow of water through the electrolyzer cell stack in response to:
 the first voltage of the first cell being greater than the voltage threshold while in the second current density, or   the second voltage of the second cell being greater than the voltage threshold while in the second current density.   
     
     
         8 . The electrolysis system of  claim 7 , wherein the controller is configured to determine that:
 the first membrane has the pinhole formed therein in response to a third voltage of the first cell being less than the voltage threshold while in the second current density and the flow of water is reversed, and/or   the second membrane has the pinhole formed therein in response to a fourth voltage of the second cell being less than the voltage threshold while in the second current density and the flow of water is reversed.   
     
     
         9 . The electrolysis system of  claim 1 , wherein the controller is configured to decrease a flow rate of water through the electrolyzer cell stack in response to holding the current density at the first current density for the predetermined time period. 
     
     
         10 . The electrolysis system of  claim 1 , wherein the pinhole monitoring system further includes an external power source configured to be selectively connected to the electrolyzer cell stack, wherein the external power source is not connected to the electrolyzer cell stack during the predetermined time period, and the controller is configured to connect the external power source to the electrolyzer cell stack in response to holding the current density at the first current density for the predetermined time period. 
     
     
         11 . A method of operating an electrolysis system, the method comprising:
 holding a current density of an electrolyzer cell stack at a first current density for a predetermined time period, the electrolyzer cell stack including a first cell and a second cell and is configured to produce a hydrogen product gas and an oxygen product gas during the predetermined time period;   decreasing the current density of the electrolyzer cell stack to a second current density in response to the predetermined time period ending; and   monitoring a first voltage of the first cell and a second voltage of the second cell using a controller while in the second current density, wherein while monitoring, the controller is configured to determine that:
 a first membrane of the first cell has a first pinhole in response to the first voltage of the first cell being less than a voltage threshold while in the second current density, and/or 
 a second membrane of the second cell has a second pinhole in response to the second voltage of the second cell being less than the voltage threshold while in the second current density. 
   
     
     
         12 . The method of  claim 11 , further comprising decreasing the current density of the electrolyzer cell stack to a third current density less than the second current density in response to:
 the first voltage of the first cell being greater than the voltage threshold while in the second current density, or   the second voltage of the second cell being greater than the voltage threshold while in the second current density.   
     
     
         13 . The method of  claim 12 , wherein the controller is configured to determine that:
 the first membrane of the first cell has the first pinhole formed therein in response to a third voltage of the first cell being less than the voltage threshold, and/or   the second membrane of the second cell has the second pinhole formed therein in response to a fourth voltage of the second cell being less than the voltage threshold.   
     
     
         14 . The method of  claim 11 , further comprising reversing a flow of water through the electrolyzer cell stack in response to:
 the first voltage of the first cell being greater than the voltage threshold while in the second current density, or   the second voltage of the second cell being greater than the voltage threshold while in the second current density.   
     
     
         15 . The method of  claim 14 , further comprising determining that:
 the first membrane has the first pinhole formed therein in response to a third voltage of the first cell being less than the voltage threshold while in the second current density and the flow of water is reversed, and/or   the second membrane has the second pinhole formed therein in response to a fourth voltage of the second cell being less than the voltage threshold while in the second current density and the flow of water is reversed.   
     
     
         16 . The method of  claim 11 , further comprising directing water through the electrolyzer cell stack at a first flow rate while in the first current density. 
     
     
         17 . The method of  claim 16 , further comprising directing water through the electrolyzer cell stack at a second flow rate in response to the predetermined time period ending, wherein the second flow rate is less than the first flow rate. 
     
     
         18 . The method of  claim 11 , further comprising disconnecting the electrolyzer cell stack from a rectifier of the electrolysis system and connecting the electrolyzer cell stack to an external power source in response to the predetermined time period ending. 
     
     
         19 . The method of  claim 11 , further comprising decreasing a pressure of the electrolyzer cell stack in response to the predetermined time period ending. 
     
     
         20 . The method of  claim 11 , wherein the second current density is about 5 mA/cm 2 .