Geothermal Technologies For Energy Production (High Enthalpy)

Production and Distribution of Electricity and Heat

Geothermal energy appears either as heat associated with emissions of steam and hot water from the ground (with a wide temperature range) or as heat available at various depths below the earth's surface. The fluids emitted from a geothermal source can have different energy content (low, medium or high enthalpy), depending on the temperature and pressure conditions. The characteristics of the source or geothermal field influence the choice of exploitation geothermal technology for electricity production, for direct use of heat for civil uses (residential heating/cooling, district heating), for agricultural and industrial processes.

High-temperature geothermal sources such as hydrothermal steam and dominant water reservoirs are in general used for the production of electricity. Electricity production from geothermal resources with fluid temperature above 150°C takes place through dry steam turbines or flash systems (double or single). Geothermal fluids at a lower temperature (usually higher than 110 °C, with even fluid re-injection into the subsoil to capture the total heat available) are used in general to run binary cycle turbine systems (more details available in the text).

In 2019, the installed geothermal capacity in the world reached 13.9 GW (IRENA, 2020), with an increase of 0.7 GW compared to 2018. The electricity generated was estimated at 95 TWh, equal to approximately 0.3% of the electricity produced in the world. In 2019, the production of electricity in Italy from geothermal energy was 6075 GWh equal to 2.1% of the national production and 5.2% of the country's renewable production

14-03-2022

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