A power generator includes a cavity to accept a hydrogen producing fuel cartridge. A channel is coupled to receive hydrogen from the fuel cartridge. A manifold is coupled to the channel to receive hydrogen from the channel, the manifold having an opening to receive oxygen and water vapor, the manifold being positioned to provide the water vapor to the cavity. An array of fuel cell membranes is supported by the manifold to receive hydrogen from the manifold and oxygen from the opening in the manifold.