TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Conditions: The elevated pressure is a pressure sufficient to prevent ambient air from entering the chamber. Hydrogen gas and oxygen gas are compressed and separately stored prior to combustion. The recovery of heat uses a high-temperature heat-exchange process. At least some of the recovered heat is used. Energy for compression is supplied at least partially from an external source chosen from solar energy, wind energy, nuclear energy, fossil fuel energy, and geothermal energy. Some of the recovered heat is used as energy input for another process, such as production of electricity. The production of electricity involves using the recovered heat to heat water to create steam to run a steam turbine (7). At least some of the electricity produced by the electricity generation process is sold or used. A temperature reducing agent is introduced into the superheated steam. The temperature reducing agent is liquid, gas, gel and/or foam. The temperature reducing agent is recovered from the produced fresh water. The temperature reducing agent and/or a portion of the steam are recovered from the combustor and/or mixing chamber. Heat is recovered from the temperature reducing agent and/or steam. Preferred Arrangement: The system further comprises compressor (1a) for compressing hydrogen gas, compressor unit (1b) for compressing oxygen gas, and storage tanks (2a,2b) for separately storing the compressed hydrogen and oxygen under pressure. The compressors are adapted to operate under elevated pressure and elevated temperature. A unit is provided for transferring hydrogen gas and oxygen gas from the storage tanks to the combustor. The combustor comprises refractory material. A unit is provided for insulating the combustor to minimize heat loss. A unit is provided for insulating the high-temperature heat-exchanger system to minimize heat loss. The wall thickness of collector is tapered along its length. The collector is adapted to operate under elevated pressure and elevated temperature. The system further comprises a storage unit for fresh water produced in the collector. A unit is provided for removing portion of the heat recovered from the collector to an industrial process, such as electrical generator (9). The system further comprises a steam mixing chamber and a unit for introducing temperature reducing agent into the combustor, collector, and/or steam mixing chamber. A unit is provided for recovering 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. A unit is provided for using the recovered heat in another process. A unit is provided for lowering the temperature of superheated steam in the combustor, steam mixing chamber, and/or collector. A unit is provided for recovering heat from lowering the temperature.