Jarðvarmi

Jarðvarmi, meaning geothermal heat, refers to heat stored in the Earth's interior that can be accessed for practical use. It arises from residual heat from the planet’s formation, differentiation of its layers, and ongoing radioactive decay in rocks and fluids. The temperature of geothermal resources varies widely, from low-temperature reservoirs suitable for direct-use heating to high-temperature systems capable of producing electricity.

Geothermal resources are harnessed in several ways. High-temperature resources (generally above 150°C) are tapped with wells to drive steam-based power plants, which may use dry steam, flash steam, or binary cycle technologies. Lower-temperature resources are used directly for applications such as district heating, space heating, hot water, greenhouse heating, aquaculture, and spa or bathing facilities. In many volcanic or tectonically active regions, jarðvarmi is a central renewable energy source.

Environmental and management considerations are important in geothermal development. While geothermal energy typically emits far less greenhouse gas than fossil fuels, it can pose challenges such as groundwater contamination, mineral scaling, and the risk of induced seismicity if not properly managed. Sustainable use often involves reinjection of produced fluids and careful reservoir monitoring to avoid overexploitation.

Global use of geothermal energy spans continents, with significant development in places like Italy, the Philippines, the United States, and Iceland. In Iceland, jarðvarmi is a key component of the energy system, supporting both electricity generation and direct-use heating through extensive district heating networks and geothermal wells.