Fuel cell system with a device for supplying fuel

A device (20) generates fuel like hydrogen and connects to a fuel feed (13) on its outlet side (22) and to a device (30) for feeding in fuel on its inlet side (21). The device for feeding in fuel has a twin-pump (34) in which an outlet material for fuel stored in a fuel tank (31) and water fed in via a feed pipe (38) are mixed into a fuel/water mixture stored in an intermediate tank (35) before being fed to the device for generating fuel.