Anode humidification

1. A method comprising:

providing a fuel flow to a fuel cell;

providing an oxidant flow to the fuel cell; and

humidifying an anode of the fuel cell, comprising saturating the oxidant flow and maintaining a temperature of the oxidant flow above a temperature of the fuel cell such that excess water propagates from a cathode of the fuel cell to the anode.

2. The method of claim 1 , wherein the excess water propagates across a membrane electrode assembly of the fuel cell.

3. The method of claim 1 , further comprising:

flowing a coolant through the fuel cell to regulate a temperature of the cell; and

using the coolant to humidify the oxidant flow prior to the oxidant flow entering the fuel cell.

4. The method of claim 3 , further comprising:

counter flowing the coolant and the oxidant flow during humidification of the oxidant flow.

5. The method of claim 1 , further comprising:

co-flowing the oxidant flow and the fuel flow in the fuel cell.

6. The method of claim 1 , further comprising:

re-circulating an anode exhaust from the fuel cell back to an anode inlet of the fuel cell to partially humidify the anode.

7. A system comprising:

a fuel cell stack comprising a cathode chamber and an anode chamber;

a fuel source to provide a fuel flow;

an oxidant source to provide an oxidant flow; and

a humidifier to saturate the oxidant flow and maintain a temperature of the oxidant flow above a temperature of the fuel cell stack such that excess water propagates from the cathode chamber to the anode chamber to at least partially humidify the anode chamber.

8. The system of claim 7 , further comprising:

membrane electrode assemblies separating the cathode chamber from the anode chamber, wherein

the excess water propagates across membrane electrode assemblies to increase humidity in the anode chamber.

9. The system of claim 7 , further comprising:

a coolant subsystem to produce a coolant flow to regulate a temperature of the fuel cell stack, wherein

the humidifier is adapted to use the coolant flow to humidify the oxidant flow.

10. The system of claim 9 , wherein the humidifier is adapted to counter flow the coolant flow and the oxidant flow inside the humidifier.

11. The system of claim 10 , wherein the counter flow of the coolant and oxidant flows inside the humidifier results in the oxidant flow leaving the humidifier at a slightly higher temperature than the coolant flow leaves the humidifier.

12. The system of claim 7 , wherein the fuel cell stack is adapted to co-flow the oxidant flow and the fuel flow inside the fuel cell stack.

13. The system of claim 7 , wherein the fuel cell system does not humidify the fuel flow before the fuel flow enters the fuel cell stack.

14. The system of claim 7 , further comprising:

a motor vehicle,

wherein the fuel cell stack, fuel source, oxidant source and humidifier are part of the vehicle.