TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Conditions: Non-fresh water is pre-treated to remove non-water materials (6) chosen from organics, algae and particulate such as sand, waste material, oil residues, metals, and other impurities. The treated non-fresh water is preheated, and the non-water materials such as salts and minerals, metals etc. are removed prior to electrolysis. The recovered non-water materials are sold. The recovery of heat uses a high-temperature heat exchanger process. The temperature of treated non-fresh water is raised to a temperature sufficient to create steam, and steam is supplied for electrolysis. At least some of the recovered heat is used for preheating the treated non-fresh water. At least some of the heat recovered from superheated steam is used. Heat is recovered from the superheated steam. Energy for electrolysis is supplied at least partially from an external source chosen from solar energy, wind energy, nuclear energy, fossil fuel energy, and geothermal energy. A high-temperature heat exchanger (11) is used for recovering heat from the superheated steam in the collector. A portion of generated hydrogen gas and oxygen gas is removed, and not used or sold. A portion of heat recovered from the collector is removed heat, and not used or some of the recovered heat is used as an energy input for another process, preferably production of electricity. The production of electricity includes using the heat to heat water to create steam to run a steam turbine. Additional hydrogen gas and oxygen gas are supplied from a source other than the high-temperature electrolysis. The non-fresh water of electrolysis is diluted. Fresh water obtained by condensing superheated steam is added to non-fresh water. Heat is extracted from cooling and compression of hydrogen gas and oxygen gas. The extracted heat is used as energy input in another process chosen from industrial processes and drying process. At least some of the electricity produced by the electrical generator is sold. High-temperature electrolysis is carried out at temperature ranging from 100 degrees C to just below thermolysis, preferably from 100 degrees C to just below 850 degrees C. Gases other than hydrogen and oxygen generated by the high-temperature electrolysis process are removed and sold. Heat is extracted from gases other than hydrogen and oxygen, and used as an energy input in another process chosen from electricity generation process and drying process. A temperature reducing agent is introduced into superheated steam, and the temperature of superheated steam is reduced. The temperature reducing agent is liquid, gas, gel and/or foam. The temperature reducing agent is removed from the produced fresh water. Preferred Arrangement: The high-temperature electrolysis unit comprises an evaporation chamber section and a high-temperature electrolysis section. The system further comprises a unit for transferring the recovered heat from the collector to the high-temperature electrolysis unit, a unit for diverting portion of heat to the evaporation chamber and the balance to the high-temperature electrolysis section, a heat-exchanging unit for transferring recovered heat to the treated water in the evaporation chamber to produce steam, a unit for transferring steam produced in the evaporation chamber to the high-temperature electrolysis section, a unit for continuously removing non-water material from the evaporation chamber section, a heat-exchanging unit for transferring the balance of recovered heat to the high-temperature electrolysis section, a unit for supplying direct current to the high-temperature electrolysis section from the alternating current/direct current converter, a unit for supplying heat from external sources to the high-temperature electrolysis section, a unit for separating hydrogen gas and oxygen gas from the steam by way of electrodes, a unit for transmitting the separated hydrogen gas from high-temperature electrolysis unit to the corresponding compressor unit and to be stored in a pressurized tank, and a unit for transmitting the separated oxygen gas from high-temperature electrolysis unit to the corresponding compressor unit for storage in a pressurized tank. The compressors are adapted to operate under elevated pressure and elevated temperature. The storage tanks (7B,8B) are adapted to store the hydrogen gas under elevated pressure. A unit is provided for insulating the evaporation section and the high-temperature electrolysis section to minimize heat loss. Units are provided for transmitting the high pressure hydrogen gas and oxygen gas from their storage tanks to the hydrogen and oxygen combustor. The combustor comprises refractory material. The thickness of wall of the collector is tapered along its length. The collector is adapted to operate under elevated pressure and elevated temperature. A storage unit is provided for fresh water produced in the collector. A unit is provided for removing portion of the generated hydrogen gas and oxygen gas. A unit is provided for removing portion of heat recovered from the collector to another process, preferably electrical generator. A unit is provided to facilitate the additional hydrogen gas and oxygen gas supplied from a source other than the high-temperature electrolysis process. The evaporation chamber section is a unit separate from the electrolysis unit. A mixing station is provided for diluting non-fresh water. A conduit connects the fresh-water storage unit to the mixing station for introducing fresh water into the mixing station. A unit is provided for extracting heat from the cooling of hydrogen gas and oxygen gas, and from the compression of such gases. A unit is provided for using the extracted heat in an industrial process chosen from adding heat to the heat recovered from the collector, electricity generation process, and drying process. A unit is provided for minimizing the corrosion of any portion in contact with salts and minerals. The high-temperature electrolysis unit also includes a collector and a combustor. The wall which the collector and combustor share in common is covered by ceramic tiles. A unit is provided for introducing the temperature reducing agent into the system at a location chosen from combustor, collector, and steam mixing chamber. A unit is provided for recovering the temperature reducing agent introduced into the system. A unit is provided for recovering heat from the system at the combustor, collector, and/or steam mixing chamber.