Abstract: An alkaline fuel cell system includes an alkaline fuel cell stack, a source of fuel gas, an oxidizer gas pump for oxidizer gas, an electrolyte tank, an electrolyte pump, an auxiliary electric storage device, and an electronic controller. The oxidizer gas pump is controlled by the electronic controller to deliver an oxidizer gas flow to the alkaline fuel cell stack which varies proportionately with the amount of electrical current drawn from the stack under any load conditions. At zero load, a minimal oxidizer gas flow is delivered to the fuel cell stack. The oxidizer gas pump may be a positive displacement pump such as a vane pump, a lobe pump, or a screw pump; or it may be a controlled blower. Also provided is a back pressure valve in the electrolyte flow circuit to maintain positive pressure in the electrolyte if the electrolyte is flowed through the fuel stack.

Abstract: A flat electrode structure for use in alkaline fuel cell stacks has electrolyte and gas inlet and outlet manifolds, with the gas manifolds being at the sides of the electrode. There is at least one gas inlet manifold and one gas outlet manifold in each side frame, and electrolyte and gas flow channels formed in the top and bottom, and side frame members. Side-to-side gas flow of the fuel gas or oxidizer gas across the electrode face is effected, with bottom to top electrolyte flow. In another embodiment of electrode structure, an embedded metal frame around the electrode serves as a current collector while stiffening the frame so as to reduce thermal expansion.