TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Components: The release/recovery mechanism comprises a pair of facing electrodes (11, 12) in water; power supply (14), which applies a voltage between the electrodes; and switch (13), which controls application of the voltage between the electrodes by the power supply, and the controller is further programmed to control the switch so that the voltage is not applied between the electrodes by the power supply when the fuel cell stack is not operating, and control the switch so that the voltage is applied between the electrodes by the power supply when the fuel cell stack is operating. It comprises an anion exchange membrane; first chamber facing the anion exchange membrane; cation exchange membrane; second chamber facing the cation exchange membrane; third chamber facing the anion and cation exchange membranes; positive electrode, which attracts anions in the water in the third chamber via the anion exchange membrane; negative electrode, which attracts cations in the water in the third chamber via the cation exchange membrane; and power supply, which applies a voltage between the positive and negative electrodes. The release/recovery mechanism comprises a permeable membrane facing the passage; chamber partitioned from the passage by the permeable membrane; and pressurizing apparatus, which pressurizes the water in the passage, and the antifreeze comprises a material, which passes through the permeable membrane depending on a pressure. It further comprises a second water circulation passage connected to the chamber; primary release/recovery mechanism to release the antifreeze into the second passage and recover the antifreeze diffused in the second passage; and a pump, which pressurizes the water in the second circulation passage.    TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Components: The antifreeze contains particles of a magnetic material, which decreases the melting point of water, and the release/discharge mechanism comprises an electromagnet, which exerts a magnetic force on the water circulating through the passage, and a power supply, which supplies an energization current to the electromagnet.