Two Geothermal energy harnessing devices, steam producing System, electricity production Method and heat energy Method are invented for mining renewable geothermal heat energy within a non-polluting, re-circulating, closed cycle intended for electricity generating applications or for other direct or indirect heat uses. The devices, the “Geothermal Energy Collector” and the “Geothermal Energy Exchanger” can work with a Depressurized Mixing Container and a Pressurized Storage Container the entirety of which comprises “THE GEOTHERMAL FLUID HEATING OR STEAM PRODUCTION SYSTEM. The system serves other equipment, such as a phase separator, steam turbine, generator and condenser, which working together with the system comprises either “THE GEOTHERMAL ELECTRICITY PRODUCTION METHOD” or “THE GEOTHERMAL HEAT ENERGY METHOD”. The GEC or GEE can work alone or within a system to add heat to any fluid and to use the heated fluid to supplement any appropriate technology, to produce electricity or for other direct or indirect uses.