Gjeotermike

Gjeotermike, or geothermal energy, is heat derived from the Earth. It can be used directly for heating or to generate electricity. The heat originates from the planet's formation and from ongoing radiogenic decay, stored in rocks and fluids beneath the surface.

Direct-use applications include district heating, greenhouse heating, aquaculture, and industrial processes that require heat. Electricity generation uses higher-temperature resources, typically by extracting steam or hot water from underground reservoirs. When natural reservoirs are insufficient, engineers can enhance or create reservoirs by circulating water through hot rock in enhanced geothermal systems (EGS).

Geothermal power plants employ several technologies: dry steam plants use underground steam to drive turbines; flash steam plants reduce high-pressure hot water to steam to drive turbines; binary-cycle plants transfer heat from geothermal fluids to a secondary working fluid with a lower boiling point to generate power. Direct-use and heat pumps exploit lower-temperature geothermal energy for space heating, domestic hot water, and industrial processes.

Advantages include baseload reliability and relatively low emissions. Challenges include resource management to avoid depletion, upfront capital costs, and potential surface disturbances. In some projects, such as certain enhanced geothermal systems, induced seismicity has been observed. Sustainable operation requires reinjection of fluids and careful environmental permitting.

Geothermal energy is most developed in regions with high subsurface temperatures close to the surface, such as tectonically active zones. Countries with notable capacity include Iceland, the United States, Indonesia, and the Philippines. Ongoing research aims to expand access through deeper drilling, lower-cost technologies, and better reservoir engineering.