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 fuel cell system, comprising:
an electrochemical hydrogen separator coupled to receive a reformate gas stream;
a power supply coupled to the electrochemical hydrogen separator, wherein current from the power supply is effective to separate hydrogen in the electrochemical separator from the reformate gas stream to produce a relatively pure hydrogen stream and a separate reformate exhaust stream;
a hydrogen storage vessel to store at least some of the hydrogen from said relatively pure hydrogen stream; and
a PEM fuel cell coupled to the electrochemical hydrogen separator and adapted to react at least a portion of the hydrogen from the reformate exhaust stream to produce power.
2. The fuel cell system of claim 1 , wherein the power supply is a power output circuit of the PEM fuel cell.
3. The fuel cell system of claim 1 , wherein the power supply is a battery.
4. The fuel cell system of claim 1 , further comprising a humidifier coupled between the electrochemical hydrogen separator and the fuel cell.
5. The fuel cell system of claim 1 , wherein the hydrogen storage vessel is coupled to the electrochemical hydrogen separator via at least one valve.
6. The fuel cell system of claim 1 , further comprising an outlet valve coupled to the hydrogen storage vessel, the outlet valve being adapted to transfer hydrogen from the hydrogen storage vessel to a secondary hydrogen storage vessel.
7. The fuel cell system of claim 6 , wherein the secondary hydrogen storage vessel is a portion of a vehicle propulsion system.
8. A method usable with a fuel cell, comprising:
providing a reformate gas stream;
routing the reformate gas stream through an electrochemical hydrogen separator;
operating the electrochemical hydrogen separator to separate hydrogen from the reformate gas stream to produce a relatively pure hydrogen stream and a separate reformate exhaust stream;
storing at least some of the hydrogen from said relatively pure hydrogen stream in a hydrogen storage vessel; and
reacting at least a portion of the hydrogen from the reformate exhaust stream in a PEM fuel cell.
9. The method of claim 8 , wherein the act of operating includes operating a power supply that receives power from the PEM fuel cell.
10. The method of claim 8 , wherein the power supply comprises a battery.
11. The method of claim 8 , further comprising:
humidifying the reformate gas stream.
12. The method of claim 8 , further comprising:
controlling when said relatively pure stream of hydrogen is stored in the hydrogen storage vessel in response to a load of the PEM fuel cell.
13. The method of claim 8 , further comprising:
coupling an outlet valve between the hydrogen storage vessel and a secondary hydrogen storage vessel.
14. The method of claim 13 , wherein the secondary hydrogen storage vessel comprises a portion of a vehicle propulsion system.