In This Article
Geothermal energy is used for three things. The U.S. Energy Information Administration sorts every application into three main types of geothermal energy systems: direct use and district heating systems, which pipe naturally hot water into baths and buildings and a short list of industrial processes; geothermal power plants, which turn deep heat into electricity; and geothermal heat pumps, which use the constant temperature near the surface to heat and cool ordinary buildings.
Those three categories are not variations on one machine. They tap different resources at different depths and temperatures, they exist in different places, and the numbers that describe them come from different datasets with different years attached. Every figure below stays pinned to its year and its scope, because the year and the scope are part of what the figure claims. If you want the primer on what geothermal energy is before reading about what it is for, start with what is geothermal energy and come back. For the origin question underneath all three — where geothermal energy comes from — the answer differs depending on whether you mean the resource or a home system.
The Direct Answer: Three Categories of Use
Here is the whole taxonomy in one table, in EIA's own order.
| EIA category | What it uses | What it is used for |
|---|---|---|
| 1. Direct use and district heating | Hot water from springs or reservoirs near the earth's surface | Bathing, heating individual buildings, heating whole districts of buildings, and a few industrial processes |
| 2. Geothermal power plants | Deep geothermal resources | Generating electricity |
| 3. Geothermal heat pumps | The constant temperature near the surface of the earth | Heating and cooling buildings |
Notice what separates them. Direct use takes water that is already hot and uses the heat as heat. Power plants convert heat into electricity, which then does whatever electricity does. Heat pumps use ground that is not hot at all, just steady, as a partner for a heating and cooling system. A claim about "geothermal energy" only becomes specific once you know which of the three it refers to.
Direct Use and District Heating
EIA lists this category first, and its examples reach furthest back. Direct use and district heating systems draw on hot water from springs or reservoirs located near the earth's surface, and the applications fall into three groups: bathing, building heat, and industry.
Bathing: the original application
Ancient Roman, Chinese, and Native American cultures used hot mineral springs for bathing, cooking, and heating, per EIA, and many hot springs are still used for bathing today. A spring needs no drilling and no conversion step, because the resource arrives at the surface already hot.
Heating buildings, one at a time or by the district
The same near-surface hot water can be piped into buildings for heat. That happens at two scales. The first is heating individual buildings directly. The second is a district heating system, where one geothermal source feeds heat to many buildings at once. EIA's flagship example: a district heating system provides heat for most of the buildings in Reykjavik, Iceland.
Industry: a short, specific list
EIA's industrial examples are food dehydration (drying), gold mining, and milk pasteurizing. EIA offers these as examples rather than a complete inventory, so treat them as illustrations of the type of work geothermal heat suits, not as the full range of it.
If what brought you to this page is heated water or growing space of your own, the residential cousins of direct use have their own guides: geothermal pool heating and the geothermal greenhouse.
Geothermal Power Plants: Electricity in Seven States
The second category uses geothermal heat to generate electricity at a power plant.
In 2025, the United States had geothermal power plants in seven states, and those plants produced about 0.4 percent of total U.S. utility-scale electricity generation, roughly 16 billion kilowatthours (BkWh). That figure carries two qualifiers. First, it is preliminary data, from EIA's Electric Power Monthly (Tables 1.3.B and 1.16.B, February 2026); final numbers can shift. Second, it covers utility-scale generation only, meaning generators of at least one megawatt.
Which seven states? EIA publishes the split two ways, and the two columns below answer two different questions. Column one asks: of all the geothermal electricity America generated, how much came from this state? Column two asks: of all the electricity this state generated, how much was geothermal?
| State | Share of total U.S. geothermal generation | Geothermal's share of the state's own generation |
|---|---|---|
| California | 68.6% | 5.2% |
| Nevada | 24.7% | 8.6% |
| Utah | 3.0% | 1.2% |
| Hawaii | 1.6% | 2.7% |
| Oregon | 1.2% | 0.3% |
| Idaho | 0.5% | 0.4% |
| New Mexico | 0.4% | 0.1% |
Source: EIA, 2025 preliminary data. "Share of total U.S. geothermal generation" sums to the national geothermal pie; "share of the state's own generation" measures how much each state leans on geothermal for its own electricity.
Read both columns and two different leaders emerge. California dominates absolute output: 68.6 percent of all U.S. geothermal generation in 2025 came from California, more than the other six states combined. But Nevada relies on geothermal more heavily than any other state in the table: geothermal supplied 8.6 percent of Nevada's own electricity generation, versus 5.2 percent of California's. California produces the most geothermal electricity; Nevada gets the largest fraction of its power from it.
The other five states are a long tail. Utah, Hawaii, Oregon, Idaho, and New Mexico together account for under 7 percent of U.S. geothermal generation, and in none of them does geothermal reach 3 percent of the state's own mix. Hawaii comes closest, at 2.7 percent.
The International Picture
Geothermal electricity is a small club worldwide, but the club has some striking members. EIA's international figures are from 2022, so treat them as a snapshot from that year rather than a current reading.
In 2022, 25 countries, including the United States, generated about 92 BkWh of electricity from geothermal energy. Indonesia was the top geothermal electricity producer, at about 17 BkWh, which covered roughly 5 percent of Indonesia's total electricity generation. The more remarkable entry is Kenya: only the seventh-highest producer at about 5 BkWh, but that 5 BkWh equaled about 43 percent of Kenya's annual electricity generation, the largest percentage share of any country, per EIA.
The U.S. figure earlier on this page (16 BkWh) is from 2025 and covers utility-scale generation only, while the 92 BkWh world total is from 2022. Those numbers come from different years and different scopes, so dividing one by the other does not produce a meaningful "U.S. share of world geothermal." EIA publishes them separately, and they should stay separate.
Geothermal Heat Pumps: The Everyday Use
The third EIA category is the one homeowners are usually shown a quote for, and it works on a completely different principle from the first two. Geothermal heat pumps use the constant temperatures near the surface of the earth to heat and cool buildings.
A heat pump does not need a hot spring, a steam reservoir, or the deep resources a power plant taps. It uses ground at its ordinary temperature, which stays far steadier across the year than the air above it. In winter the system moves heat from that steady ground into the building; in summer it runs the exchange in reverse and moves heat from the building into the ground. The output is not electricity and not naturally hot water. It is home comfort: heating and air conditioning for a regular house.
This is why the geography of heat pumps is nothing like the geography of geothermal power. The seven states with geothermal power plants are the ones with a deep resource to tap. A heat pump asks much less of the ground beneath it. If this is the version of geothermal you are weighing for your own home, the full treatment is in geothermal heating and cooling.
The Number Nobody Publishes
Nobody publishes a reliable count of how many geothermal heat pumps are installed in the United States. None of the federal bodies that track U.S. energy data (DOE, EIA, USGS, NREL), and not the international agency IRENA, currently publishes a census of installed U.S. geothermal heat pump units.
The closest authoritative number comes from the Department of Energy's GeoVision report, published in May 2019, using 2016 data. DOE put installed U.S. geothermal heat pump capacity at 16.8 gigawatts-thermal (GWth), and converted that capacity into an equivalency, writing that it "is equivalent to GHP installations in about 2 million households." DOE credits that capacity figure to a 2016 survey by Lund and Boyd rather than measuring it directly.
The heat pump is the geothermal category closest to everyday life, and yet it is the one category where the basic "how many exist?" question has no authoritative answer. Power plants are large, licensed, and metered, so EIA can tell you their output to the tenth of a percent. Residential heat pumps are small, private, and installed one property at a time, and no agency aggregates them into a published count.
The one thing to remember
Geothermal energy is used three ways, in EIA's taxonomy: direct use and district heating (bathing, building heat, Reykjavik's district system, plus food drying, gold mining, and milk pasteurizing), power plants (0.4% of U.S. utility-scale electricity across seven states in 2025, preliminary data), and heat pumps (heating and cooling ordinary buildings from the steady near-surface ground). Every reliable number in this subject carries a year and a scope; the famous "2 million U.S. systems" figure is a 2016 capacity equivalency, not a count.
Frequently Asked Questions
What are the three main uses of geothermal energy?
Per EIA, the three main types of geothermal energy systems are: direct use and district heating systems (using naturally hot water for bathing, building heat, and some industry), geothermal power plants (generating electricity), and geothermal heat pumps (heating and cooling buildings using constant near-surface ground temperatures).
How is geothermal energy used in homes?
Through a geothermal heat pump, which uses the constant temperature of the ground near the surface to heat the house in winter and cool it in summer. This is a different technology from geothermal power plants: it needs no hot springs or volcanic geology, just ordinary ground. See geothermal heating and cooling for the full picture.
What industries use geothermal energy?
EIA gives three examples of industrial direct use: food dehydration (drying), gold mining, and milk pasteurizing. All three use geothermal hot water as process heat. EIA presents them as examples rather than a complete list.
How much U.S. electricity comes from geothermal energy?
In 2025, geothermal power plants in seven states produced about 0.4%, or roughly 16 billion kWh, of total U.S. utility-scale electricity generation, per preliminary EIA data (Electric Power Monthly, February 2026). "Utility-scale" covers generators of at least 1 MW, so smaller installations are outside that figure.
Which country uses the most geothermal electricity?
In 2022, Indonesia was the top geothermal electricity producer at about 17 BkWh, per EIA. But Kenya, the seventh-highest producer, drew about 43% of its annual electricity generation from geothermal, the largest percentage share of any country. Biggest producer and most geothermal-reliant are different titles.
How many geothermal heat pumps are installed in the United States?
No federal agency publishes a reliable count. The closest figure is DOE's GeoVision report (2019), which estimated 2016 installed capacity at 16.8 GWth, which DOE described as equivalent to geothermal heat pump installations in about 2 million households. That is a capacity equivalency, not a count of installed units.
Sources
- U.S. Energy Information Administration — Geothermal explained: Use of geothermal energy (three-category taxonomy; direct-use applications including bathing history, Reykjavik district heating, and the three industrial applications; 2025 preliminary U.S. generation figures and seven-state table, from Electric Power Monthly, Tables 1.3.B and 1.16.B, February 2026; 2022 international figures for 25 countries, Indonesia, and Kenya; heat pump definition).
- U.S. Department of Energy — GeoVision: Harnessing the Heat Beneath Our Feet (full report, May 2019) (2016 installed U.S. geothermal heat pump capacity of 16.8 GWth, which DOE credits to Lund and Boyd 2016 and describes as equivalent to installations in about 2 million households).