What Is Geothermal Power?

Geothermal energy comes from heat stored beneath the Earth’s surface, primarily from the decay of radioactive elements in the mantle and core, plus residual heat from the planet’s formation. This heat can be accessed by drilling wells to reach hot water or steam reservoirs, which are used to drive turbines for electricity or provide direct heating for buildings, greenhouses, or industrial processes.

There are three main types of geothermal power plants:

• Dry Steam: Steam is piped directly from underground to spin turbines (e.g., The Geysers in California).
• Flash Steam: High-pressure hot water is flashed into steam to generate electricity (most common globally).
• Binary Cycle: Hot water heats a secondary fluid with a lower boiling point, which vaporizes to drive turbines (ideal for lower-temperature resources).

Geothermal can also be used for direct heating (e.g., district heating in Iceland) or with geothermal heat pumps for residential and commercial heating/cooling.

The Potential of Geothermal Power

The Earth’s mantle and core hold an immense amount of heat. The U.S. Geological Survey estimates the Earth’s geothermal resource could theoretically supply 10,000 times the world’s annual energy consumption. However, only a fraction is currently accessible due to technological and economic limits. Key points about its potential:

• Abundant Resource: The Earth’s heat is effectively inexhaustible on human timescales, with geothermal gradients (temperature increases with depth) averaging 25-30°C per kilometer. Hot spots like volcanic regions or tectonic boundaries offer even higher temperatures closer to the surface.
• Reliable Baseload Power: Unlike solar or wind, geothermal provides constant energy, making it a stable complement to intermittent renewables. A single geothermal plant can operate at 90%+ capacity year-round.
• Global Availability: While prime geothermal sites are in tectonically active areas (e.g., Iceland, New Zealand, Indonesia), enhanced geothermal systems (EGS) could unlock resources in less favorable regions by fracturing hot dry rock to create reservoirs.
• Low Carbon Footprint: Geothermal emits 5-10% of the CO2 per kilowatt-hour compared to fossil fuels, aligning with net-zero goals. International Energy Agency (IEA)

For example, the U.S. has about 3.7 gigawatts (GW) of installed geothermal capacity, enough to power 3 million homes, but this is only 0.4% of its electricity mix. Globally, geothermal produces ~16 GW, with countries like Indonesia and Kenya expanding rapidly due to their volcanic geology.

Recent Advancements in Geothermal Power

Geothermal is seeing renewed interest due to technological innovations and the push for clean energy. Here are key advancements as of 2025:

• Enhanced Geothermal Systems (EGS): EGS involves injecting water into hot dry rock to create artificial reservoirs, expanding geothermal potential to non-volcanic areas. In 2024, Fervo Energy’s Cape Station project in Utah achieved a breakthrough, reaching 3.5 MW with plans to scale to 400 MW by 2028. Fervo Energy
• Deep Drilling Technologies: Advances in drilling, like plasma drilling and laser-assisted bits, allow access to deeper, hotter resources (5-10 km). Projects like Quaise Energy aim to drill 20 km into the Earth’s crust, targeting temperatures above 500°C for supercritical geothermal systems. Quaise Energy
• Hybrid Systems: Combining geothermal with solar or biomass increases efficiency. For instance, Enel Green Power’s Stillwater plant in Nevada integrates solar and geothermal for consistent output.
• Closed-Loop Systems: Companies like Eavor use closed-loop geothermal, circulating fluid through sealed pipes in hot rock, eliminating the need for natural reservoirs. Eavor’s pilot in Germany reached 1 MW in 2024. Eavor
• Policy Support: The U.S. Department of Energy’s $7 billion investment in clean energy includes geothermal R&D, with goals to reduce costs by 90% by 2035. The EU’s REPowerEU plan also funds geothermal for district heating. U.S. Department of Energy

These innovations are making geothermal more accessible and cost-competitive, especially in regions previously considered unsuitable.

Why Geothermal Takes a Backseat

Despite its potential, geothermal lags behind other renewables for several reasons:

• High Upfront Costs: Drilling wells and building plants can cost $4-10 million per megawatt, compared to $1-2 million for solar or wind. Exploration risks (e.g., dry wells) deter investors.
• Geographic Limitations: Prime geothermal sites are concentrated in tectonically active regions like the “Ring of Fire.” EGS could expand access, but it’s still in early stages and expensive.
• Long Development Times: Geothermal projects take 5-10 years from exploration to operation, compared to 1-3 years for solar or wind farms.
• Competition with Renewables: Solar and wind benefit from lower costs (down 80% since 2010) and simpler deployment. In 2024, solar and wind added 300 GW globally, dwarfing geothermal’s 0.5 GW growth. IRENA
• Public Awareness: Geothermal lacks the visibility of solar panels or wind turbines. Misconceptions about seismic risks from EGS also hinder acceptance, though studies show minimal impact.
• Infrastructure Challenges: Scaling geothermal requires specialized drilling expertise and supply chains, which are less developed than for fossil fuels or other renewables.

These factors make geothermal a niche player, contributing less than 1% of global electricity despite its vast potential.

The Future of Geothermal Power

Geothermal’s role is growing as technology and policy catch up. The IEA projects geothermal could reach 100 GW globally by 2050 if costs drop and EGS scales. Key trends include:

• Decarbonizing Industry: Geothermal can provide high-temperature heat for industries like cement or steel, cutting emissions where electrification is challenging.
• Urban Heating: Cities like Munich and Reykjavik are expanding geothermal district heating, reducing reliance on gas. Europe aims for 10% of heating from geothermal by 2030.
• Tech Sector Demand: Data centers, needing reliable power for AI, are turning to geothermal. Google and Microsoft have signed deals with Fervo Energy for geothermal-powered data centers.
• Global Expansion: Countries like Indonesia (aiming for 7 GW by 2030) and Kenya (2 GW planned) are leveraging their geothermal resources to meet energy demands.

To compete, geothermal needs continued R&D, streamlined permitting, and public-private partnerships to de-risk projects. Initiatives like the U.S. Geothermal Energy Office and the EU’s Geothermal Alliance are steps in this direction.

Conclusion

Geothermal power, fueled by the Earth’s mantle, holds immense potential as a reliable, low-carbon energy source. Innovations like EGS, deep drilling, and closed-loop systems are unlocking new opportunities, but high costs, geographic constraints, and competition from cheaper renewables keep it in the background. As technology advances and climate goals tighten, geothermal could move from a niche player to a cornerstone of the energy transition. For now, it’s a sleeping giant, waiting for the right mix of investment and innovation to shine.

If you want more details on a specific aspect, like EGS or geothermal’s role in a particular region, let me know!