Abstract: A fuel cell system includes: a fuel cell that includes a cathode and an anode and generates electricity by reducing a mediator at the cathode; a regenerator that oxidizes, with an oxidant, the mediator reduced by the cathode; an oxidant feed path that is connected to the regenerator, wherein through the oxidant feed path, the oxidant to be supplied to the regenerator flows; a reformer; a combustor that heats the reformer; and a first heat exchanger that exchanges heat between combustion exhaust discharged from the combustor and the oxidant to be supplied to the regenerator.

Abstract: A fuel cell system includes: a fuel cell that has a cathode and an anode and generates electricity by reducing a mediator at the cathode; a regenerator that oxidizes, with an oxidant, the mediator reduced by the cathode; a reformer; a combustor that heats the reformer; and a heating medium path that heats the regenerator, wherein through the heating medium path, combustion exhaust discharged from the combustor or a heat medium heated through heat exchange with the combustion exhaust flows.

Abstract: A fuel cell system includes: a fuel cell that includes an anode and a cathode and generates electricity by reducing a mediator at the cathode; a regenerator that oxidizes the mediator reduced by the cathode; a first path that leads from the cathode to the regenerator and through which the mediator reduced by and discharged from the cathode is guided to the regenerator; a second path that leads from the regenerator to the cathode and through which the mediator oxidized at the regenerator is returned to the cathode; and a first heat exchanger that exchanges heat between a first fluid and a second fluid, the first fluid being a fluid flowing in the first path and containing the mediator reduced by cathode, and the second fluid being a fluid flowing in the second path and containing the mediator oxidized at the regenerator.

Abstract: A fuel cell system includes a fuel cell, a regenerator, an oxidant feed path, a gas discharge path, and a heat exchanger. The fuel cell includes an anode and a cathode and reduces a mediator with the cathode. The regenerator oxidizes, with an oxidant, the mediator reduced by the cathode. Through the oxidant feed path, the oxidant is guided to the regenerator. Through the gas discharge path, the gas present inside the regenerator is guided out of the regenerator. The heat exchanger heats the oxidant by exchanging heat between the oxidant flowing in the oxidant feed path and the gas flowing in the gas discharge path.

Abstract: A fuel cell system includes: a fuel cell that includes a cathode and an anode and generates electricity by reducing a mediator at the cathode; a regenerator that oxidizes, with an oxidant, the mediator reduced by the cathode; an oxidant feed path that is connected to the regenerator, wherein through the oxidant feed path, the oxidant to be supplied to the regenerator flows; a reformer; a combustor that heats the reformer; and a first heat exchanger that exchanges heat between combustion exhaust discharged from the combustor and the oxidant to be supplied to the regenerator.

Abstract: A fuel cell system includes: a fuel cell that has a cathode and an anode and generates electricity by reducing a mediator at the cathode; a regenerator that oxidizes, with an oxidant, the mediator reduced by the cathode; a reformer; a combustor that heats the reformer; and a heating medium path that heats the regenerator, wherein through the heating medium path, combustion exhaust discharged from the combustor or a heat medium heated through heat exchange with the combustion exhaust flows.

Abstract: A fuel cell system includes: a fuel cell that includes an anode and a cathode and generates electricity by reducing a mediator at the cathode; a regenerator that oxidizes the mediator reduced by the cathode; a first path that leads from the cathode to the regenerator and through which the mediator reduced by and discharged from the cathode is guided to the regenerator; a second path that leads from the regenerator to the cathode and through which the mediator oxidized at the regenerator is returned to the cathode; and a first heat exchanger that exchanges heat between a first fluid and a second fluid, the first fluid being a fluid flowing in the first path and containing the mediator reduced by cathode, and the second fluid being a fluid flowing in the second path and containing the mediator oxidized at the regenerator.

Abstract: A fuel cell system includes a fuel cell, a regenerator, an oxidant feed path, a gas discharge path, and a heat exchanger. The fuel cell includes an anode and a cathode and reduces a mediator with the cathode. The regenerator oxidizes, with an oxidant, the mediator reduced by the cathode. Through the oxidant feed path, the oxidant is guided to the regenerator. Through the gas discharge path, the gas present inside the regenerator is guided out of the regenerator. The heat exchanger heats the oxidant by exchanging heat between the oxidant flowing in the oxidant feed path and the gas flowing in the gas discharge path.

Abstract: A fuel cell system includes a fuel cell that includes an anode and a cathode and generates electricity by reducing a mediator at the cathode, a regenerator that oxidizes the mediator, a fuel gas feed path through which fuel gas to be supplied to the anode flows, a humidifier that is disposed in the fuel gas feed path and humidifies the fuel gas, and a water collection path that extends from the regenerator to the humidifier and guides to the humidifier at least one selected from steam produced at the regenerator and condensation formed from the steam.