Why is geothermal energy used extensively for heating buildings in Iceland?

Iceland makes extensive use of geothermal energy for heating buildings primarily because of its unique geological location. The country sits directly atop the Mid-Atlantic Ridge, a major tectonic plate boundary where the North American and Eurasian plates diverge.1

This intense tectonic activity results in significant volcanism, which brings magma close to the Earth's surface. This magma transfers heat to groundwater, creating large underground reservoirs of hot water and steam. Iceland possesses more hot springs and solfataras than any other country, providing a readily accessible and abundant source of thermal energy.23

By drilling into these subsurface systems, Iceland can extract hot water to provide space heating for buildings. This practice is highly developed, with Reykjavík hosting the world's largest and most famous geothermal district heating system, which has supplied the vast majority of the city's residences since the mid-1970s.4