NOVELTY - A fuel battery apparatus comprises an improver (1) and a main body (3) which use sea water as fuel. The improver isolates hydrogen from the fuel. Hydrogen is supplied to the main body where it is ionized into protons and reacted with oxygen in an electrolyte, to produce electricity. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a system which utilizes the heat energy and water from the fuel battery. Water resulting from the reaction of protons and water is utilized as the heat source for the improver. ELECTRICAL POWER AND ENERGY - Preferred Fuel Battery: The improver is a photocatalyst system or an electrolyzer. The photocatalyst system optically catalyzes the decomposition of sea water into hydrogen and oxygen. The electrolyzer decomposes sea water into hydrogen and oxygen. The sea water comprising anions and cations functions as the electrolyte. The fuel for the improver is modified methane or ethanol. A solar battery is connected in parallel to the fuel battery apparatus. Electric power generated by the fuel battery apparatus and a solar battery is utilized for the electrical equipments in the vessel. Preferred System: Water formed in the fuel battery filtered with the addition of minerals in a filter and used as potable water. The systems which utilize the power and water generated by the fuel battery apparatus include a hot liquid supply installation (28), an air conditioner and electrical equipments inside the vessel. The water is also supplied to a hot liquid supply installation (28) of the vessel. The waste heat (produced from water) from the fuel battery and the heat from the solar battery are utilized as heat source for the heater (27) of hot liquid supply installation. The waste heat from fuel battery is utilized in the absence of solar power. Waste heat from the fuel battery is also used as heat source for an airconditioner. The air conditioner is a floor heating apparatus having piping provided below the floor of the vessel. Warm water used in the floor heating apparatus is guided back to the fuel battery apparatus (configured below the floor of the vessel) or hot liquid supply installation.    USE -   The fuel battery apparatus and the solar battery generate power for the electrical equipments of vessels. The fuel battery apparatus is used for driving propeller of the vessel and is also integrated to an internal combustion engine of the vessel (all claimed).    ADVANTAGE -   Efficient utilization of the fuel battery is enabled. DESCRIPTION OF DRAWING - The figure shows the block diagram of the fuel battery and the system which utilizes the heat energy from the fuel battery. (1) Improver; (3) Fuel battery main body; (27) Heater; (28) Hot liquid supply installation