What lies ahead for geothermal energy?

The outlook for geothermal energy can be encapsulated in one word: Expansion.

Geothermal power is frequently regarded as the third or fourth most significant renewable energy source, trailing solar, wind, and hydro. Currently, it represents only a minor fraction of global power capacity—approximately 10,709.7 MW in 2010. However, experts predict a swift increase in geothermal plant installations worldwide.

The underlying technology is straightforward and has been well-known for decades. The inaugural commercial geothermal power plant was established in Larderello, Italy, back in 1911. As elementary science teaches us, heat is perpetually produced by a magma layer beneath the Earth's crust. This heat ascends to the surface, reaching its peak in areas with active volcanoes and seismic zones between tectonic plates.

Despite the variety of geothermal power plants, their core function remains consistent: they harness steam or hot water rising from the Earth to generate electricity.

Geothermal energy is anticipated to become increasingly significant in the future due to advancements in drilling efficiency, enabling more energy to be extracted from each well.

Engineers have developed and refined 'binary cycle' plants, which emit only water vapor. Unlike traditional 'dry steam' plants that release greenhouse gases—albeit significantly less than coal plants—binary cycle plants use a closed-loop system. Hot water passes through a heat exchanger, heating a secondary liquid like isobutane, which boils at a lower temperature. The water is then reinjected underground, while the isobutane drives the generator.

As technology advances, geothermal energy is becoming more cost-effective. The Union of Concerned Scientists reports that operational costs have dropped by up to 50% since 1980. In some regions, geothermal power is nearing cost parity with fossil fuels.

The most promising advancement is Enhanced Geothermal Systems (EGS). Currently, only about 10% of the world's land is suitable for geothermal energy production, as it requires hydrothermal convection zones. EGS aims to expand this by injecting water into 'hot dry rock' areas, unlocking geothermal potential in previously unsuitable locations.

Why should we invest in such technology? As the USUCS highlights, the heat within 10,000 meters (approximately 33,000 feet) of Earth's surface holds 50,000 times more energy than all global oil and natural gas reserves combined.

That’s the reason.

Numerous researchers, including the US Department of Energy, Google, and key players in the geothermal industry, are actively advancing this technology. While challenges exist—such as concerns about induced seismic activity, similar to issues linked with fracking (though without harmful chemicals entering aquifers)—scientists consider the risks minimal. Developing Enhanced Geothermal Systems (EGS) could unlock enormous reserves of clean, renewable energy.

Another promising idea is converting depleted oil and gas wells into geothermal plants. These existing wells could be repurposed into geothermal operations, offering a simpler and more cost-effective alternative to drilling new ones.

Geothermal energy undeniably holds immense potential. Predictions about its role in a clean energy future vary—some experts, like cleantech innovator Saul Griffith, estimate it could supply about one-sixth of global energy, while the IPCC projects a 4% contribution. Regardless, geothermal will be a crucial component of the renewable energy mix as fossil fuels phase out.