Fuel cells and methods of operating fuel cells are disclosed. In one aspect, the invention features a fuel source for a fuel cell including a housing having an outlet, a structure having a portion in the housing, the structure defining a cavity and having a surface defining an opening in fluid communication with the cavity, and a fuel in the housing. The fuel is in fluid communication with the outlet through the opening and the cavity of the structure.
1. A fuel cell system, comprising:
a fuel cell;
a fuel source comprising
a housing having an outlet in gaseous communication with the fuel cell,
a non-gaseous fuel, comprising an alcohol or a hydrocarbon, within the housing, and
a vapor transmission element in the non-gaseous fuel and comprising a cavity and openings that prevent the non-gaseous fuel from passing into the cavity while allowing the non-gaseous fuel that converts to a gaseous fuel including to pass into the cavity,
wherein when the fuel cell system is in operation the non-gaseous fuel converts to gaseous fuel that passes through the openings into the cavity, then through the outlet of the housing, and then to the fuel cell; and
a gas mover between the fuel cell and the fuel source along a flow path of the gaseous fuel that regulates the flow of gas to and/or from the fuel cell.
2. The fuel cell system of claim 1 , wherein the gas mover is between the outlet of the housing and the fuel cell along the flow path of the gaseous fuel.
3. The fuel cell system of claim 1 , wherein the housing of the fuel source further comprises an inlet and the gas mover is between the inlet of the housing and the fuel cell along the fluid flow path of the gaseous fuel.
4. The fuel cell system of claim 1 , wherein the gas mover comprises a fan.
5. The fuel cell system of claim 1 , wherein the vapor transmission element comprises a diffusion tube.
6. The fuel cell system of claim 1 , further comprising a valve between the fuel cell and the fuel source that partially or completely reduces the flow of gaseous fuel from the fuel source to the fuel cell when the fuel cell system is not in use.
7. The fuel cell system of claim 1 , wherein the fuel source is in gel form.
8. The fuel cell system of claim 1 , wherein the vapor transmission element comprises a plurality of elongated tubes, each tube defining a cavity and having a surface defining a plurality of openings.
9. The fuel cell system of claim 1 , wherein the non-gaseous fuel comprises methanol.