ENERGY SECURITYInterest in Geothermal Energy is Growing

By Gero Rueter

Published 9 January 2023

These days, some 400 power plants in 30 countries generate electricity using steam generated beneath the earth’s surface, producing a total capacity of 16 gigawatts (GW). Despite its advantages, geothermal energy has seen limited use compared to fossil fuels, but recent energy shocks have increased interest in this energy source.

At some 6,000 degrees Celsius (11,000 degrees Fahrenheit), Earth’s core is about as hot as the sun. Though not comparable, even at 2,000 to 5,000 meters (6,500 to 16,000 feet) beneath the surface of the planet, it can be a scorching 60 to 200 C, while in volcanic regions, even surface temperatures can reach 400 degrees.

That makes for a lot of potential heat-based energy. Our ancestors were no strangers to the power of geothermal energy, as it is known. In the first century AD, Romans living in the western German cities now known as Aachen and Wiesbaden heated their houses and thermal baths with hot spring water. In New Zealand, the Maori people cooked their food using the Earth’s heat, and in 1904, geothermal energy was used to generate electricity in central Italy’s Larderello.

Volcanic Areas Turn Geothermal Energy into Electricity
These days, some 400 power plants in 30 countries generate electricity using steam generated beneath the earth’s surface, producing a total capacity of 16 gigawatts (GW).

This method of generating electricity is particularly important in volcanic regions along the Pacific Ring of Fire, including the United States, Mexico, El Salvador, Iceland, Turkey, Kenya, Indonesia, the Philippines and New Zealand. But on a global level, geothermal energy only accounts for 0.5% of electricity generation.

Heat from Deep Geothermal Energy Is Available Everywhere
Across the world, geothermal energy is mainly used for heating swimming pools, buildings, greenhouses and for urban heating systems. Water up to 200 degrees C is pumped from boreholes up to 5,000 meters deep. The heat is then extracted and the cooled water is pumped back in through a second bore.

This method of heat capture is feasible worldwide, inexpensive and increasingly popular in countries that lack volcanic activity. According to assessments by the Renewables Global Status Report, the installed capacity of geothermal heat plants is currently 38 gigawatts worldwide — more than double the capacity of geothermal power plants that generate electricity.

To date, China (14 GW), Turkey (3 GW), Iceland (2 GW) and Japan (2 GW) are the leaders in developing deep geothermal energy, heating more and more city districts and greenhouses. In Germany, the city of Munich enjoys inexpensive geothermal heating and has set its sight on using the technology to make the sector climate neutral by 2035.