Method and apparatus for electrochemical compression and expansion of hydrogen in a fuel cell system
View Patent ↗The invention relates to fuel cell systems and associated methods of operation where an electrochemical cell such as a fuel cell is used as an electrochemical hydrogen separator to separate hydrogen from a process stream (e.g., reformate or synthesis gas), or as an electrochemical hydrogen expander to inject hydrogen into a process stream. In one aspect, the invention provides a method of operating a fuel cell system, including the following steps: flowing hydrogen from a hydrogen supply conduit through a fuel cell to provide an electric current to a load coupled to the fuel cell; actuating an electrochemical hydrogen separator in a first mode of operation of the system to transfer hydrogen from the hydrogen supply conduit to a hydrogen storage vessel; and actuating an electrochemical hydrogen expander in a second mode of operation of the system to transfer hydrogen from the hydrogen storage vessel to the fuel cell.
1. A method of operating a fuel cell system, comprising:
placing an electrical potential across a first fuel cell in a first mode of operation to transfer hydrogen from hydrogen gas in an anode chamber of the first fuel cell to a cathode chamber of the first fuel cell to produce a first flow of hydrogen gas in the cathode chamber;
placing an electrical load across the first fuel cell in a second mode of operation to transfer hydrogen from hydrogen gas in the cathode chamber of the first fuel cell to the anode chamber of the first fuel cell to produce a second flow of hydrogen gas in the anode chamber; and
flowing air through the anode chamber of the first fuel cell and hydrogen through the cathode chamber of the first fuel cell in a third mode of operation to provide an electric current to a load coupled to the first fuel cell.
2. The method of claim 1 , further comprising:
supplying reformate from a reforming reactor to the anode chamber.
3. The method of claim 1 , further comprising:
operating a compressor in the first mode of operation to pressurize a hydrogen storage vessel with the hydrogen transferred from the anode chamber to the cathode chamber.
4. The method of claim 1 , further comprising:
transferring hydrogen in the first mode of operation from the cathode chamber to a hydrogen storage vessel; and
transferring hydrogen from the hydrogen storage vessel to a secondary hydrogen storage vessel.
5. The method of claim 4 , wherein the secondary hydrogen storage vessel is a portion of a vehicle propulsion system.
6. The method of claim 1 , further comprising:
monitoring an electrical load on a second fuel cell;
switching the system to the first mode of operation when the load is below a first predetermined threshold; and
switching the system to the second mode of operation when the load is above a second predetermined threshold.
7. The method of claim 1 , further comprising:
flowing hydrogen from the anode chamber of the first fuel cell to a reforming reactor in the second mode of operation.
8. The method of claim 1 , further comprising:
flowing hydrogen from the anode chamber of the first fuel cell to a second fuel cell in the second mode of operation.
9. The method of claim 1 , in the first mode of operation, further comprising:
flowing the hydrogen from the cathode chamber of the first fuel cell across a desiccant.
10. The method of claim 1 , in the second mode of operation, further comprising:
flowing the hydrogen from the anode chamber of the first fuel cell through a humidifier.
11. A method of operating a fuel cell system, comprising:
flowing hydrogen from a hydrogen supply conduit through a fuel cell to provide an electric current to a load coupled to the fuel cell;
actuating an electrochemical hydrogen separator in a first mode of operation of the system to transfer hydrogen from the hydrogen supply conduit to a hydrogen storage vessel; and
actuating an electrochemical hydrogen expander in a second mode of operation of the system to transfer hydrogen from the hydrogen storage vessel to the fuel cell.
12. The method of claim 11 , further comprising:
supplying reformate from a reforming reactor to the hydrogen supply conduit.
13. The method of claim 11 , further comprising:
operating a compressor to pressurize the hydrogen storage vessel with hydrogen from the electrochemical hydrogen separator.
14. The method of claim 11 , further comprising:
transferring hydrogen from the hydrogen storage vessel to a secondary hydrogen storage vessel.
15. The method of claim 11 , further comprising:
monitoring the load coupled to the fuel cell;
performing the step of actuating an electrochemical hydrogen separator when the load is below a first predetermined threshold; and
performing the step of actuating an electrochemical hydrogen expander when the load is above a second predetermined threshold.
16. The method of claim 11 , further comprising:
flowing hydrogen from the electrochemical hydrogen expander to a reforming reactor in the second mode of operation.
17. The method of claim 11 , further comprising:
flowing hydrogen from the electrochemical hydrogen expander to the hydrogen supply conduit in the second mode of operation.
18. The method of claim 11 , further comprising:
flowing the hydrogen from the electrochemical hydrogen separator across a desiccant.
19. The method of claim 11 , further comprising:
humidifying the hydrogen transferred from the hydrogen storage vessel in the second mode of operation.
20. A method of operating a fuel cell system, comprising:
flowing hydrogen from a hydrogen supply conduit through a fuel cell to provide an electric current to a load coupled to the fuel cell;
exhausting unreacted hydrogen from the fuel cell to a hydrogen exhaust conduit;
actuating an electrochemical hydrogen separator in a first mode of operation of the system to transfer hydrogen from the hydrogen exhaust conduit to a hydrogen storage vessel; and
actuating an electrochemical hydrogen expander in a second mode of operation of the system to transfer hydrogen from the hydrogen storage vessel to the fuel cell.
21. The method of claim 20 , further comprising:
supplying reformate from a reforming reactor to the hydrogen supply conduit.
22. The method of claim 20 , further comprising:
operating a compressor to pressurize the hydrogen storage vessel with hydrogen from the electrochemical hydrogen separator.
23. The method of claim 20 , further comprising:
monitoring the load coupled to the fuel cell;
performing the step of actuating an electrochemical hydrogen separator when the load is below a first predetermined threshold; and
performing the step of actuating an electrochemical hydrogen expander when the load is above a second predetermined threshold.
24. The method of claim 20 , further comprising:
flowing hydrogen from the electrochemical hydrogen expander to a reforming reactor in the second mode of operation.
25. The method of claim 20 , further comprising:
flowing hydrogen from the electrochemical hydrogen expander to the hydrogen supply conduit in the second mode of operation.
26. The method of claim 20 , further comprising:
flowing the hydrogen from the electrochemical hydrogen separator across a desiccant.
27. The method of claim 20 , further comprising:
flowing the hydrogen from the electrochemical hydrogen expander through a humidifier.
28. A fuel cell system comprising:
a hydrogen storage vessel;
a hydrogen supply conduit; and
a fuel cell to function as an electrochemical hydrogen separator in a first mode of operation of the system to transfer hydrogen from the hydrogen supply conduit to the hydrogen storage vessel, and operate as an electrochemical hydrogen expander in a second mode of operation of the fuel cell system to transfer hydrogen from the hydrogen storage vessel to the fuel cell.
29. The fuel cell system of claim 28 , further comprising:
a reforming reactor to supply reformate to the hydrogen supply conduit.
30. The fuel cell system of claim 28 , further comprising:
a subsystem to monitor a load coupled to the fuel cell,
cause the fuel cell to function as the electrochemical hydrogen separator in response to the load being below a first predetermined threshold, and
cause the fuel cell to function as the electrochemical hydrogen expander in response to the load being above a second predetermined threshold.