Passive formic acid fuel cell

A passive direct formic acid fuel cell comprising:

• a cathode, an anode, and a membrane electrode assembly between the anode and the cathode wherein;
• the anode comprises a body having an inlet at a first end and an outlet at a second end opposite the first end, a flow channel in the body that is fluidly coupled to and extends between the inlet and the outlet, the anode body has an upstream section comprising an upstream portion of the flow channel and a downstream section comprising a downstream portion of the flow channel, and the downstream section has a higher flow channel volume density than the upstream section, fuel cell stack wherein;
• at least one fuel cell wherein in an operational orientation the anode inlet of the fuel cell is at a top of the anode and the anode outlet is at a bottom of the anode, a fuel delivery reservoir fluidly coupled to the anode inlet and located above the anode when the system is in the operational orientation, the reservoir configured to provide a sufficient hydrostatic head of fuel such that fuel can flow from the reservoir and through the anode by gravity, a fuel cartridge fluidly coupled to the anode outlet and located below the anode when the system is in the operational orientation and having a chamber for storing fuel and receiving unreacted fuel and reaction products from the anode, and a manually actuated priming pump fluidly coupled at an intake end to the fuel cartridge and at a discharge end to the fuel delivery reservoir, the fuel cartridge further comprising;
• at least one vent in fluid communication with gas inside the chamber and a manually actuated priming pump in fluid communication with the fuel cartridge and anode inlet and configured to pump fuel in the fuel cartridge to the anode, drain port, a porous weight having a negative buoyancy in formic acid fuel, and a flexible drain tube having a discharge end in fluid communication with the drain port and an intake end attached to the weight such that the intake end is in fluid communication with formic acid fuel in the chamber irrespective of the orientation of the fuel cartridge.

A passive direct formic acid fuel cell comprising:

• a cathode, an anode, and a membrane electrode assembly between the anode and the cathode wherein;
• the anode comprises a body having an inlet at a first end and an outlet at a second end opposite the first end, a flow channel in the body that is fluidly coupled to and extends between the inlet and the outlet, the anode body has an upstream section comprising an upstream portion of the flow channel and a downstream section comprising a downstream portion of the flow channel, and the downstream section has a higher flow channel volume density than the upstream section, a fuel cell stack wherein;
• at least one fuel cell wherein in an operational orientation the anode inlet of the fuel cell is at a top of the anode and the anode outlet is at a bottom of the anode, a fuel delivery reservoir fluidly coupled to the anode inlet and located above the anode when the system is in the operational orientation, the reservoir configured to provide a sufficient hydrostatic head of fuel such that fuel can flow from the reservoir and through the anode by gravity, a fuel cartridge fluidly coupled to the anode outlet and located below the anode when the system is in the operational orientation and having a chamber for storing fuel and receiving unreacted fuel and reaction products from the anode, and a manually actuated priming pump fluidly coupled at an intake end to the fuel cartridge and at a discharge end to the fuel delivery reservoir, the fuel cartridge further comprising;
• at least one vent in fluid communication with gas inside the chamber and a manually actuated priming pump in fluid communication with the fuel cartridge and anode inlet and configured to pump fuel in the fuel cartridge to the anode, a vent port located at a bottom end of the chamber, a float having a positive buoyancy in formic acid fuel, a vent tube having a discharge end fluidly coupled to the vent port, and an intake end coupled to the float such that the intake end is in fluid communication with gas inside the chamber.