Some geothermal power plants make electricity using a secondary fluid

Geothermal power can generate electricity and provide direct heating for homes

By drilling several kilometers through penetrable rock, wells can access highly pressurized groundwater warmed by thermal energy trapped beneath Earth's surface. This water can be turned into steam to create electricity in generators. Heating systems several meters deep can pump fluid underground before circulating it through buildings.

Geothermal power plants can provide large-scale energy storage for other systems

These facilities can store excess energy from solar and wind power as hot water or steam, which can be used to run turbines to generate electricity when other renewable energy sources are unavailable. Simulations have found efficiencies of 90% during a storage-use cycle, making it comparable to lithium-ion batteries.

Fracking technology can help make geothermal power possible almost everywhere

Generating electricity from Earth's thermal energy has previously required existing underground reservoirs of hot water and permeable rocks through which the fluid naturally escapes. Today, fractures can be artificially created to form fluid pathways, and surface water can be injected underground and brought back to the surface.

Unlike solar panels, which convert sunlight directly into electricity, concentrated solar power systems focus sunlight to heat a material that boils water, which then drives a turbine-generator to produce electricity.

Enhanced geothermal power systems can trigger earthquakes by injecting fluid into rock, increasing subterranean pressure.

Geothermal power can be used beyond heating and energy production

Depending on the depth of the natural vents or artificial wells drilled, the surrounding fluid temperature will vary greatly—from 10 to 371 degrees Celsius (50 to 700 degrees Fahrenheit)—allowing for various applications, including the drying of cement, concrete, and lumber, as well as the processing of pulp and paper.

In osmotic power systems, the natural movement of water from regions of low to high salt concentration is used to generate electricity from pressurized water.

Heat pumps use an easily boilable chemical to regulate temperature

In air conditioners, warm air is pulled from a home to turn a refrigerant into a gas, which is then compressed, raising its temperature. The gas naturally releases this energy to the comparatively cooler environment when exposed, then expands and is reused in the system. Heaters run in reverse, with the refrigerant picking up energy from the comparatively warmer environment.

Visualize how alternating currents—electricity that periodically changes direction—are generated by rotating magnetic fields, as occurs in turbine-generator systems.

Sand 'batteries' can store excess electricity from the power grid as thermal energy

Energy collected from solar or wind power is used to heat insulated silos full of sand to temperatures as high as 450 degrees Celsius (842 degrees Fahrenheit), which can be retained for long periods. These thermal energy storage systems can be designed to boil water and generate electricity when needed.

The world's first geothermal power plant was built in 1913 in Devil's Valley

In Tuscany, Italy, Prince Piero Ginori-Conti of Trevignano established the plant nine years after creating a generator that powered five light bulbs using steam vents in the area. Within three years, a second plant was built with two generators, each with 10 times the energy output of the first.

In nuclear reactors, water acts as a coolant and moderator, slowing neutrons produced in nuclear reactions so they are more likely to interact with nuclear fuel and generate sustainable energy.

Wastewater from geothermal power plants helps melt sidewalk snow in Iceland

Located on the Mid-Atlantic ridge, where the North American and Eurasian tectonic plates move apart, the nation saw geothermal power meet more than 90% of its heating demand in 2024. After the hot water produced by these plants is used to heat homes and businesses, it is transferred through small pipes beneath Reykjavík's sidewalks.

The continuous decay of radioactive elements regenerates geothermal energy reserves

Geothermal power is a renewable energy source derived from Earth's interior, where the core reaches temperatures exceeding 5,000 degrees Celsius (9,000 degrees Fahrenheit). These temperatures result from leftover energy from collisions during planetary formation, with radioactive decay in the core releasing additional energy that travels to the surface.

Desalination involves costly, energy-intensive methods for producing freshwater

Thermal desalination heats saltwater to produce steam, and reverse osmosis forces saltwater through a membrane that only allows water through. In both cases, freshwater is collected and remineralized for consumption, while wastewater brine is often returned to the ocean, where it may harm marine organisms.

Geothermal power can reduce the dangerous mining of rare earth elements

Geothermal brines—mineral-rich underground fluids extracted for use in geothermal plants—contain small concentrations of REEs that can be recovered after energy generation. Although researchers suggest that this retrieval requires complex extraction methods at a significant scale to account for high flow rates, the chemical processes also occur in traditional REE processing.

As of 2022, just 0.5% of installed renewable energy capacity worldwide is geothermal

Despite being able to generate electricity regardless of the weather, solar (28%) and wind (27%) are far more prevalent, primarily because of their lower upfront costs. Geothermal plants use 88% less space than solar farms to produce the same energy, but have been restricted to geologically active regions.

Aquifer thermal energy storage systems bank water heated during the summer in aquifers—layers of porous rock, gravel, and sand filled with groundwater—which are then collected in winter to warm homes.

Watch a server submerged in a fluid continue to run and stay cool by boiling the liquid away.

Some renewable energy sources may weaken the resiliency of electric grids by removing outage buffers provided by coal- and natural gas-fired plants, which provide the system with more time to find a new power source if a plant goes down.

Geothermal power may meet 15% of global electricity demand growth through 2050

According to the International Energy Agency, the estimate would require the construction of geothermal capacity with an annual output equivalent to the combined electricity consumption in the US and India in 2024. The report suggests geothermal investment will reach $2.5T by 2050, with the integration of fracking technologies decreasing costs by 80% by 2035.

Data centers can be kept cool by circulating fluid over plates atop high-temperature components or by submerging equipment in non-corrosive oil that does not conduct electricity.

If two strands of conducting materials are connected at two junctions, electricity can be generated if one junction is heated while the other is cooled—a phenomenon known as the Seebeck effect.

When users prompt AI chatbots, both cooling systems that support data centers and power plants that rely on steam cycles to generate electricity for data centers contribute to water use.

Explore next-generation geothermal projects worldwide

This tool from the Clean Air Task Force allows users to see the location of geothermal power systems to depths of 12.5 kilometers (7.8 miles), where temperatures reach about 450 degrees Celsius (842 degrees Fahrenheit), including proposed, abandoned, and in-development projects.

Like nuclear power, US geothermal power plant construction stalled for decades

Development and investment into geothermal energy took off in the 1960s. However, by the 1980s, companies repeatedly failed to find reservoirs of hot water when exploring new locations, and investors lost interest in the expensive drilling required. By the 2020s, technological advancements had finally helped mitigate exploration risk and expand viable drilling locations.

Hydrogen fuel cells, which combine hydrogen and oxygen to generate electricity and water, can be run in reverse to produce hydrogen fuel from water.

Geothermal heat pumps have the greatest upfront cost of any home heating system

As of 2025, installations of these systems can range from $15,000 to over $40,000, significantly more than for furnace-air conditioner and air-source heat pump systems. However, they are up to 50% more efficient than these alternative systems, making them able to pay for themselves within 15 years.

Solar power is converting the sun's energy into thermal or electrical energy

Solar energy is the most abundant renewable energy resource. It can be captured in photovoltaic cells to generate electricity, solar heating and cooling technologies for temperature control, and concentrated solar power to drive steam turbines.

Rain-catching tubes provide new hydropower source for tropical regions

An experiment in Singapore showed that charge separation could be established by rainwater flowing through narrow tubes. The separation, which creates a voltage, could be scaled up in regions of high rainfall to provide a clean energy source.

Windmills can be designed to pump groundwater for irrigation or land drainage

A gearbox within the windmill converts the windmill's rotation into the vertical motion of a piston that pushes water up a pipe. It also drives the rotation of an Archimedes screw to move water to higher elevations.

Among renewable sources, geothermal rivals hydropower in lifetime cost

As of 2024, the levelized cost of energy—the average cost per unit of energy over the lifetime of a power plant—for geothermal power is surpassed only by solar photovoltaic and onshore wind. Geothermal's LCOE has remained relatively unchanged since 2007, with significant decreases held back by significant upfront installation costs.

Since 2026, the Large Hadron Collider has provided heat to thousands of French homes and businesses through a system that harnesses hot water from the accelerator's cooling circuits.

Explaining the Leidenfrost effect, where water can hover and move against gravity

Water droplets can glide across surfaces whose temperatures are well above water's boiling point. This heat instantly vaporizes the bottom of the droplet, creating a layer of steam that the rest of the droplet rides and bounces upon. This can be seen when sprinkling water on skillets to determine if the surface is hot enough to cook on.

Dirty lightning is a thunderstorm created from friction between rising and falling flows of ash and smoke during volcanic eruptions.

Microreactors are 100 to 1,000 times smaller than traditional nuclear reactors but still generate thermal energy for heating or electricity by splitting atomic nuclei.

An overview of hydropower

Hydropower, or the use of the natural flow of moving water to generate electricity, is one of the oldest and largest sources of renewable energy.

A basement of mechanical systems—collectively called the technosphere—supports B2

Twenty-six underground air handlers heat, cool, filter and manage the humidity of the air across the biomes of Biosphere 2. The above-ground Energy Center complex provides continuous power to these and other systems, including heating and cooling water for laboratory experiments and personal use.

Clean energy technologies are more mineral-intensive than burning fossil fuels

Solar panels use silver due to its high conductivity, hydropower plants use chromium in their steel alloys, and geothermal plants need titanium to withstand abundant heat and pressure. Lithium—used in energy storage—is expected to see over 500% increased demand from 2020 to 2025.

Our bodies cool us down by sweating because water requires a significant amount of energy to change state from liquid to gas, making it an ideal medium for carrying thermal energy away from our bodies.

Water vapor is used to manage heat in high-end smartphones

While smartphones have traditionally been cooled using a highly conductive plate that dissipates heat from the chip, vapor chambers offer a higher heat-removal capacity. This technology has been utilized in laptops for decades to absorb heat by cycling a fluid between liquid and gaseous phases.

Data centers require interconnected server- and building-level cooling systems

Computer equipment can be cooled by circulating cold air or water through the equipment racks, siphoning the heated fluid into a heat exchanger. This exchanger transfers thermal energy to building cooling systems, which can dispose of the heat by evaporative cooling—the way humans cool off by sweating—or via air conditioning.

A look at hydrothermal vents, where barophiles and hyperthermophiles survive boiling water

Discovered in 1977 during an exploration of the Galapagos Rift, these seafloor openings spew hot magma and chemicals that heat seawater to hundreds of degrees. Without the sunlight found at depths of less than 1,000 meters (3,281 feet), extremophiles in these environments convert released chemicals into energy to survive, alongside surviving extreme pressures.

The Geysers is the largest geothermal power complex in the world

Despite the Mayacamas Mountains area north of San Francisco lacking geysers, the name given by a grizzly bear hunter stuck after the construction of The Geysers Resort Hotel to accommodate tourists. Natural steam vents in the region are funneled into more than 12 geothermal plants, each capable of powering about 40,000 homes.

View a breakdown of global electricity generation in 2025, led by coal power plants.

Internal-combustion engines convert fuel into motion using controlled explosions

Gasoline engines mix fuel and air, compressing it and igniting it to create thousands of tiny explosions that push pistons up and down. This movement spins the crankshaft, which moves a vehicle's wheels.

Ingenuity and advanced engineering have allowed trains to overcome extreme landscapes

The Jungfrau Railway utilizes electric trains powered by hydroelectric energy to ascend the Swiss Alps, while Poland's Elbląg Canal hauls ships along cable-powered tracks driven by waterwheels. Germany's Wuppertal monorail navigates bends as it glides over a river valley, and New Mexico's Holloman High-Speed Test Track can achieve speeds of Mach 8.6 for rocket sleds.

Since 2022, two-thirds of data centers have been built in water-stressed areas

In residential evaporative cooling systems, 10% of consumed water is lost to evaporation compared to 80% in data centers. Although some companies have pledged to become water-positive—replenishing more freshwater than they consume—by 2030 through a transition to air cooling, only 10% of data center operators track water use across all their facilities.

While carbon capture and storage systems collect carbon dioxide at the source, such as power plants, direct air capture systems extract it from the atmosphere.

Wind energy is categorized into land-based, distributed, and offshore types

Distributed wind turbines efficiently serve on-site energy needs, while land-based turbines are large and generate cost-competitive electricity. Offshore wind turbines capture powerful winds above the ocean and may be pounded into the seafloor using pile drivers or built to float above water at scales larger than the Statue of Liberty.