Geothermal energy produces electricity around the clock using heat from the Earth’s interior, making it one of the few renewable sources that can replace the steady, always-on power we currently get from burning fossil fuels. While solar panels sit idle at night and wind turbines stall on calm days, a geothermal plant keeps running with availability rates above 90%. That reliability, combined with minimal carbon emissions and a tiny land footprint, is the core reason geothermal energy has a growing role in the shift away from fossil fuels.
It Runs When Other Renewables Can’t
The electricity grid needs a constant, predictable supply of power to match demand every second of the day. Coal and natural gas have traditionally filled that role because you can burn fuel continuously. Solar and wind are clean, but they’re intermittent: U.S. solar farms operated at a 24.4% capacity factor in early 2025, meaning they produced about a quarter of their maximum possible output over time. Wind performed somewhat better at 34.2%. Geothermal plants, by contrast, hit a 65.9% capacity factor in the same period, according to the U.S. Energy Information Administration. Some individual plants run above 90%.
That distinction matters enormously as grids add more solar and wind. Without a reliable clean source filling the gaps, utilities lean on natural gas “peaker” plants to keep the lights on during cloudy or windless stretches. Geothermal can fill that role instead, providing steady carbon-free power without needing backup from fossil fuels. It also supplies what grid engineers call ancillary services: the moment-to-moment adjustments in power output that keep voltage and frequency stable across the network. A grid with more geothermal is a grid that needs less gas.
Extremely Low Carbon Emissions
Geothermal power produces a fraction of the greenhouse gases that come from fossil fuels, even when you count emissions from drilling wells, manufacturing equipment, and building the plant. A systematic review from the National Renewable Energy Laboratory found that lifecycle emissions range from about 11 to 47 grams of CO2 equivalent per kilowatt-hour, depending on the plant design. The cleanest type, a binary cycle plant using high-temperature reservoirs, averaged just 11.3 g CO2eq/kWh. For comparison, natural gas plants typically emit around 400 to 500 g CO2eq/kWh over their lifecycle, and coal exceeds 800.
Binary cycle plants are especially clean because the underground fluid never contacts the atmosphere. It passes through a heat exchanger, transfers its energy to a separate working fluid that spins a turbine, then gets reinjected underground. Flash steam plants, which let hot water partially vaporize at the surface, release slightly more CO2 that’s naturally dissolved in the geothermal fluid, but still land well under any fossil fuel source.
A Tiny Land Footprint
Geothermal plants take up remarkably little space for the energy they produce. Data from Our World in Data shows that some geothermal installations need as little as 8 square meters per megawatt-hour of electricity generated annually. Solar farms require 18 to 27 times more land per unit of energy than nuclear (the most land-efficient source), and coal needs roughly 50 times more than nuclear. Geothermal falls close to the compact end of the spectrum because the energy source is underground. The surface infrastructure is mostly a collection of wellheads, pipes, and a turbine building.
This compact footprint makes geothermal viable in places where land is expensive or ecologically sensitive. A plant can sit on a few dozen acres and produce hundreds of megawatts, while a solar installation delivering equivalent annual energy would sprawl across thousands of acres.
Massive Untapped Potential
Global geothermal capacity stands at roughly 15 gigawatts as of 2024, with about 0.4 GW added that year. That’s a small number compared to solar and wind, but it reflects a geographic limitation that’s now being overcome. Traditional geothermal requires naturally occurring reservoirs of hot water or steam near the surface, which limits development to volcanic regions like Iceland, the western United States, Indonesia, and East Africa.
Enhanced geothermal systems (EGS) change the equation. Instead of searching for natural reservoirs, EGS technology drills deep into hot rock, fractures it, and circulates water through the cracks to extract heat. This approach could work almost anywhere with enough depth. The U.S. Geological Survey estimates that the Great Basin of the Southwest alone holds 135 GW of EGS potential. Broader projections suggest up to 150 GW of cost-effective geothermal generation could operate in the United States in coming decades, and the National Renewable Energy Laboratory estimated 90 GW could be economically built nationwide by 2050. For context, the entire U.S. currently has about 1,200 GW of total generating capacity, so 90 to 150 GW of new geothermal would represent a significant share of the grid.
Low Water Use Compared to Fossil Fuels
Power plants that burn fuel need vast amounts of water for cooling. In 2020, coal-fired generation withdrew an average of 21,406 gallons per megawatt-hour, and natural gas combined-cycle plants used about 2,793 gallons per megawatt-hour. Binary geothermal plants use far less water because they operate in a closed loop: the geothermal fluid stays sealed inside the system and gets reinjected underground. Air-cooled binary plants can reduce water consumption to near zero, which makes geothermal especially attractive in arid regions where water scarcity is already a concern.
A Source of Critical Minerals
Geothermal fluids carry dissolved minerals picked up from deep rock formations, and some of those minerals are exactly the ones needed for batteries and electronics. Lithium is the headline example. The U.S. Department of Energy estimates domestic geothermal brines hold a resource potential exceeding 600,000 tons of lithium, which currently surpasses annual U.S. demand. Extracting lithium as a byproduct of geothermal power could shift the country from a net importer to a net exporter, reducing dependence on foreign supply chains for electric vehicle batteries and grid-scale energy storage.
Only one U.S. plant currently extracts lithium from geothermal brine at commercial scale, but the economics improve as both geothermal energy and lithium demand grow. Producing power and minerals from the same well makes each product cheaper, since the drilling costs are shared.
Grid Diversity Reduces Risk
An electricity grid that depends on just one or two energy sources is fragile. Natural gas prices can spike during cold snaps. Drought reduces hydropower output. Extended cloud cover and calm weather can suppress solar and wind generation simultaneously across a large region. Geothermal adds a fundamentally different type of resource to the mix: one that doesn’t depend on weather, fuel deliveries, or water levels in reservoirs.
Because the Earth’s heat is constant and locally sourced, geothermal plants are also resilient to supply chain disruptions. They don’t import fuel, and once a well is drilled, the energy source is essentially permanent on any human timescale. Plants routinely operate for 30 years or more, and the underground heat reservoir replenishes naturally as long as the system is managed properly. This fuel security is why geothermal is sometimes described as using the Earth itself as an inexhaustible battery.
The combination of these traits, always-on reliability, near-zero emissions, minimal land and water use, mineral co-production, and immunity to fuel price volatility, is what makes geothermal uniquely valuable. No single renewable source checks all of those boxes. As drilling technology improves and enhanced geothermal systems unlock hot rock beneath most of the country, geothermal is positioned to shift from a niche resource into a foundational piece of clean energy grids worldwide.