A cryogenic fluid delivery system includes a main tank system with a main tank adapted to contain a first supply of cryogenic liquid, and reserve tank system with reserve tank adapted to contain a second supply of cryogenic liquid. A pressure building circuit is adapted to delivery vapor to the head space of the main tank to build pressure in the main tank and a fuel delivery line supplies cryogenic fuel from either the main tank or the reserve tank to a use device. The reserve tank stores saturated cryogenic fuel that is delivered to the use device via the fuel delivery line while the cryogenic liquid in the main tank is being saturated. The fluid delivery system automatically switches to delivering cryogenic fuel from the main tank to the use device via the fuel delivery line upon saturation of the cryogenic liquid in the main tank.