A visual crash course on geothermal energy

TECHNOLOGY
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A visual crash course on geothermal energy

Geothermal is a lesser-known type of renewable energy that uses heat from the Earth’s molten core to produce electricity.

While this unique resource offers important benefits over solar and wind energy, geothermal energy also suffers from high costs and geographic restrictions. Because of this, few countries have managed to produce geothermal energy at scale.

In this infographic, we use a combination of diagrams and graphs to provide a high-level overview of this sustainable energy source.

How does geothermal work

Geothermal energy is produced by accessing hot water reservoirs that lie several kilometers below the Earth’s surface. In certain parts of the planet, this water naturally breaks through the surface, creating what is known as hot spring (or, in some cases, a geyser).

When accessed through a well, this pressurized water rises and rapidly expands into steam. This steam is used to turn a turbine, which drives an electric generator.

Later in the process, excess steam is condensed back into water as it passes through a cooling tower. Finally, an injection well pumps this water back to Earth to ensure sustainability.

Where is geothermal energy being used?

In 2021, global geothermal power generation totaled 16 gigawatts (GW). However, only a handful of countries have crossed the 1 GW milestone.

CountryInstalled Capacity (GW)
🇺🇸 USA3.7
🇮🇩 Indonesia2.3
🇵🇭 Philippines1.9
🇹🇷 Turkey1.7
🇳🇿 New Zealand1
🇲🇽 Mexico1
🇮🇹 Italy0.9
🇰🇪 Kenya0.9
🇮🇸 Iceland0.8
🇯🇵 Japan 0.6
🌎 Rest of the World1.1

To put these numbers in context, consider the following data points:

  • America’s 3.7 GW capacity is split between 61 geothermal power plants.
  • The largest solar plant in the world, the Bhadla Solar Park, has a maximum output of 2.2 GW
  • The largest hydroelectric plant in the world, the Three Gorges Dam, can produce up to 22.5 GW

Although geothermal plants produce less energy, they have advantages over other types of renewable energy. For example, geothermal energy is not affected by day and night cycles, weather conditions or seasons.

the big picture

We now look at a second dataset, which shows the global contribution of each type of renewable energy. These numbers are from April 2022 and were provided by the International Renewable Energy Agency (IRENA).

ModelInstalled Capacity (% of total)Installed Capacity (GW)
hydro40%1226
Solar28%858
Wind27%827
Others
(geothermal)
5%
(0.5%)
153
(15*)
Total100%3064

*The total geothermal capacity in this dataset differs from the previous figure of 16 GW. This is due to different fonts and rounding.

One reason for the slow adoption of geothermal energy is that it can only be built in regions with suitable geological characteristics (such as places where there is volcanic activity).

To expand on this point, consider the following data from Fitch Solutionswhich shows the predicted growth of geothermal power capacity by region.

Fitch believes that most new geothermal capacity will be installed in Asia over the next decade. On the other hand, investment in North America and Western Europe (NAWE) is expected to decline.

In the coming years, NAWE will experience a gradual slowdown in geothermal capacity additions as we expect investments to be dampened by cheaper wind and solar projects.
– Fitch Solutions

Major markets for geothermal energy are expected to be IndonesiaThe Philippinesand New Zealand, which lie along the Pacific Ring of Fire. The Ring of Fire is a path along the Pacific Ocean where most of the volcanic activity takes place.

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