Geothermal energy, the heat inside the earth, is captured via power plants that generate steam to make electricity, or via heat pumps.

In the former, utility-scale method, wells are drilled deep into the earth to pump steam or hot water to the surface at high pressure. At the surface, the pressure is dropped, causing the water to turn into steam. The steam spins a turbine connected to a generator, producing electricity. In a cooling tower, the steam condenses back into water, which is then pumped back into the earth to begin the process anew.

Geothermal power plants are usually found in areas with hot springs, geysers, or volcanic activity. In the United States, they are primarily situated in the western states and Hawaii, with California generating the most electricity from this renewable source.

At the residential level, ground source heat pumps can heat and cool houses, and heat swimming pools. In this setting, heat is transferred by pumping water  or a refrigerant through a loop of vertical or horizontal pipes buried just below ground level, where the temperature is constant. During the winter, the liquid absorbs warmth from the earth and it is pumped to the structure above. The liquid cools following the heat transfer and is pumped back underground, repeating the process. In warm weather, the process runs in reverse.

Ground-source heat pumps run on electricity, a more environmentally friendly heating and cooling system than fossil fuel-based technology, depending upon how that electricity is powered. If powered by renewables, the electricity is emissions-free. Geothermal energy works in most climates, and can offer up to a 70% reduction in heating and a 50% decrease in cooling costs. Up-front installation costs are high, but systems generally pay for themselves in five to seven years. Ground-source heat pumps can require alterations to the landscape, and open-loop geothermal systems, while uncommon, can contaminate groundwater.

For climates with moderate heating and cooling needs, you can install heat pumps without geothermal (and, therefore, without digging into the ground). Air-source heat pumps move heat, in the winter, from the cool outdoors into your home and, in the heat of the summer, move heat from your home into the outdoors. A vastly cheaper way to heat and cool. Much more here.

A Canadian company recently sent us a heat pump glossary which you might find useful.

State and municipal level goals, and mandates to transition from fossil fuels to renewable energy, are among the factors expected to spur growth in geothermal energy.


Column: Good news for 100% clean energy. Geothermal has finally arrived

By Sammy Roth 06/25/24
In the fight against climate change, they’re humanity’s mighty Avengers: Solar panels. Wind turbines. Electric cars. And now, superheated rocks. Geothermal power plants — which tap scorching-hot underground rocks and reservoirs to generate renewable electricity…
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A First-In-The-Nation Networked Geothermal Neighborhood in Framingham

By Alan Earls 06/05/24
As Massachusetts communities spearhead the delivery of clean energy to help the commonwealth meet its leading decarbonization goals, Eversource is proud to announce the commissioning of its first-in-the-nation networked geothermal neighborhood in Framingham, Massachusetts. Over…
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Making geothermal heat pumps work for big buildings

By David Roberts 04/26/24
The most efficient way to heat and cool an individual building is with an electric heat pump, for the simple reason that, instead of generating heat, heat pumps harvest it, which turns out to be…
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Clean energy in Texas, wildfire and flood in Canada and Russia, and how to engage your elected officials

I didn’t anticipate how incredibly awe-inspiring a total eclipse would be, when the last fraction of the moon slipped over the sun and all you could see was the corona. It reminded me how powerfully…
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Geothermal cuts emissions and costs at these Minnesota public schools

By Frank Jossi 03/28/24
Geothermal heating and cooling is emerging as a go-to technology for Minnesota school district St. Paul Public Schools as it seeks to renovate aging facilities in line with the district’s climate action plan. Minnesota’s second-largest…
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In Texas, ex-oil and gas workers champion geothermal energy as a replacement for fossil-fueled power plants

By Emily Foxhall 03/26/24
In 2009, on a plot of shrub-covered cattle land about 45 miles northwest of McAllen, Shell buried and abandoned a well it drilled to look for gas. The well turned out to be a dry…
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A geothermal energy boom could be coming to Chicago’s South Side

By Juanpablo Ramirez-Franco 02/23/24
Naomi Davis won’t lose her faith in the earth. At a recent community meeting in Chicago’s South Side she wanted to drive the point home — that the city’s Black community will not be left…
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Is Geothermal About to Become the Solar of the 2020s?

By Matthew Zeitlin 02/14/24
Fervo Energy is getting a lot better at drilling holes. According to data presented this week at Stanford University, it took the company 71 days to drill a geothermal well back in 2022. But last…
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Smith College, MA embarks on $220-million geothermal project

By Carlo Cariaga 11/01/23
The Smith College in Northampton, Massachusetts has started work on a geothermal system to make their heating and cooling carbon-neutral by 2030.
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Drill, Baby, Drill: The Promise of Geothermal Power

By David Gelles 08/31/23
Clean energy has become synonymous with wind and solar, and with good reason. Thanks to improved technology and declining costs, wind turbines and solar panels are producing a rapidly growing share of the world’s electricity.
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There’s a Vast Source of Clean Energy Beneath Our Feet. And a Race to Tap It.

By Brad Plumer 08/28/23
In a sagebrush valley full of wind turbines and solar panels in western Utah, Tim Latimer gazed up at a very different device he believes could be just as powerful for fighting climate change —…
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Enhanced geothermal power is finally a reality

By David Roberts 07/21/23
Traditional geothermal power, which has been around for over a century, exploits naturally occurring fissures underground, pushing water through them to gather heat and run a turbine. Unfortunately, those fissures only occur naturally in particular…
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Enhanced Geothermal Shot

The Enhanced Geothermal Shot™ is an initiative to help usher in a clean energy future by bringing enhanced geothermal systems to Americans nationwide. It is part of the U.S. Department of Energy’s Energy Earthshots Initiative…


Utah FORGE is a dedicated underground field laboratory sponsored by the Department of Energy (DOE) for developing, testing, and accelerating breakthroughs in Enhanced Geothermal Systems technologies to advance the uptake of geothermal resources around the…

Geothermal explained

Geothermal reservoirs are naturally occurring areas of hydrothermal resources. These reservoirs are deep underground and are largely undetectable above ground.

Are geothermal heat pumps right for you? Comparing pros and cons

Ground source heat pumps (GSHPs) are an innovative heating and cooling technology, but they may not be suitable for every property. It’s important to understand the pros and cons of ground source heat pumps, and…

What is geothermal energy?

In the global push to end reliance on fossil fuels, green energy sources like solar and wind power have gotten lots of attention. But geothermal energy is another environmentally friendly energy source. It’s the underground…

What is Geothermal?

The Geothermal Resources Council (GRC), Geothermal Energy Association (GEA), and Geothermal Exchange Organization (GEO) have released guidance for U.S. states on meeting new clean energy standards from the U.S. Environmental Protection Agency (EPA).

Geothermal energy

This key renewable source covers a significant share of electricity demand in countries like Iceland, El Salvador, New Zealand, Kenya, and Philippines and more than 90% of heating demand in Iceland. The main advantages are…

The Forgotten Renewable: Geothermal Energy Production Heats Up

Three and a half hours east of Los Angeles lies the Salton Sea, a manmade oasis in the heart of the Mojave Desert. It was created in 1905, when a canal broke and the Colorado…

5 Things to Know About Geothermal Power

Geothermal energy—energy derived from the heat of the earth—can be harnessed both as a source of renewable electricity as well as directly for heating and cooling applications. The U.S. Department of Energy (DOE) funds geothermal…

Geothermal: Energy we can all agree on

Heat and cool your home using the Earth's natural temperature. In these divisive times, geothermal may be the one thing we can all agree on – even if the reasons why are completely different.


Here’s how geothermal energy heats and cools a home

By Isabella O' Malley   07/13/23  
Some homeowners looking to switch out their heating and cooling systems are turning to home geothermal — also known as ground source — heat pumps. It’s a technology that relies on a simple physical fact:…
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The Massive ‘Batteries’ Hidden Beneath Your Feet

By Matt Simon   04/12/23  
WHEN RAINWATER FALLS, it soaks down into an aquifer, a layer of porous rock or loose materials like sand or gravel. For thousands of years, humans have been digging into these bands of liquid to…
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Meet the Geothermal Champions

By Hiroko Tabuchi   03/28/23  
There’s a lot to like about geothermal energy. It’s clean, it’s renewable and it generates electricity 24/7. It taps heat from Earth’s interior that, in theory, will last billions of years.
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Renewable energy company threatens to sue Biden over endangered toad

By Sammy Roth   03/23/23  
The nation’s largest geothermal power company is preparing to sue the Biden administration over its decision to protect a tiny toad, in the latest high-stakes showdown between renewable energy development and wildlife conservation.
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Geothermal Power, Cheap and Clean, Could Help Run Japan. So Why Doesn’t It?

By Hiroko Tabuchi   03/22/23  
A treasured getaway for travelers in Japan is a retreat to one of thousands of hot spring resorts nestled in the mountains or perched on scenic coasts, some of which have been frequented for centuries.
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Geothermal’s new momentum and old hurdles

By Ben Geman   03/08/23  
Next-wave geothermal startup Eavor on Tuesday finalized a contract for roughly $96 million in grant financing from the EU Innovation Fund for a project in Germany, CEO John Redfern said in an interview.
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Oil and Gas Technology and Geothermal Energy Development

The U.S. energy industry is undergoing a decades-long transition that includes increased
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The extraordinary potential value of enhanced geothermal power

By David Roberts   09/30/22  
In recent years, excitement has been growing about the potential of geothermal energy, which draws heat from the Earth’s crust to generate electricity. I wrote a couple of introductory pieces on it for Vox a…
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The Ultimate Clean Energy Is About To Get 90% Cheaper

By Will Locket   09/16/22  
To stop the self-made apocalypse that is climate change, we need to stop pumping the atmosphere full of carbon dioxide — something that is far easier said than actually done. Part of the issue is…
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Geothermal heating and cooling: Renewable energy’s hidden gem

By Philip Warburg   08/04/22  
Often described as a giant tower of Jenga blocks, Boston University’s Center for Computing and Data Sciences shows no outward signs of leading the race to sustainable energy design. No rooftop wind turbines grace its…
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Presentation on the Utility Thermal Energy Network and Jobs Act: A RenewableTransition

A presentation on what thermal energy networks are, and how they will transform the way we heat and cool our buildings, and why both labor unions and environmentalists unified to enable utilities to build them.
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Jamie Beard: How can we tap into the vast power of geothermal energy?

By Manoush Zomorodi   05/20/22  
Geothermal energy is a clean, renewable, nearly limitless energy source. Technologist Jamie Beard wants us to use more of it — and to do that, she's recruiting experts from the fossil fuel industry.
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DOE Announces $12 Million to Boost Geothermal Energy Research

The U.S. Department of Energy (DOE) today announced $12 million in funding for seven research projects to advance the commercialization of enhanced geothermal systems (EGS) — manmade reservoirs that produce clean, renewable energy. EGS development…
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Microsoft’s new campus will run on geothermal energy – but what exactly is it and can it really help combat climate change?

By World Economic Forum   09/14/21  
Microsoft is using geothermal energy from deep underground to power its new sustainable campus in the United States. The computing giant is building 93,000 square metres of new workspace on 29 hectares of its Redmond…
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Earth To Senator Joe Manchin: Geothermal Energy. That’s It. That’s The Message.

By Tina Casey   07/16/21  
The US has yet to tap its vast geothermal energy resources, and a movement is finally afoot to kick the domestic industry into high gear. That includes the iconic coal and gas producing state of…
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This Overlooked Energy Source Could Supply 50% Of Electricity

Miles below the Earth’s surface, there’s enough thermal energy to power all of humanity for the foreseeable future. It’s called geothermal energy, and it’s poised to play an increasingly large role as a source of always…
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Geothermal Energy Is Having A Magic Moment, This Time For Real – CleanTechnica Interview

By Tina Casey   03/07/21  
The geothermal energy industry has never realized its true potential in the US, despite the seemingly magical promise of nonstop, 24/7 renewable energy sitting just below the surface of the Earth. However, it seems like…
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Innovative geothermal micro-district concept moves ahead in Massachusetts

By Sarah Shemkus   12/03/20  
An example of a ground source heat pump system, extracting both heat and cooling from the ground underneath a Kansas courthouse. Utilities could prove useful partners in the projects, which involve drilling, trenching and laying…
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With geothermal as baseload and solar for peak-load, University of Utah reaches 71% renewables

By Alexander Richter   10/08/20  
The University of Utah achieved more than 50% of its energy needs covered by renewables adding a geothermal power purchase agreement in 2018 and has now upped its share of renewable energy to 71% with…
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This New Mexico Power Plant Uses Geothermal Energy In A New Way

By Johnny Wood   02/26/20  
Geothermal energy is growing, spreading beyond traditional volcanic regions like Iceland and New Zealand. While using the earth’s heat to generate heat and electricity is nothing new, what has changed is that technology is now…
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Dutch tomatoes and sustainable agriculture with geothermal as key ingredient

By Alexander Richter   02/26/20  
The Dutch agriculture sector, particularly the greenhouse sector is showing the world the way on sustainable horticulture for food production, with geothermal energy as a key ingredient.
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U.S. Geological Survey (USGS) maintains resourceful website with geothermal data

By Alexander Richter   02/26/20  
The U.S. Geological Survey maintains a website with great resources on geothermal energy potential in the United States, including data, maps, publications and more.The U.S. Geological Survey maintains a website with great resources on geothermal…
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Geothermal heating district could rise in Mattapan

By Jon Chesto   02/11/20  
City officials say they’re backing the project because it would further Boston’s ‘commitment to climate action’.
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Most of the University of Utah’s electricity will now be fueled by renewable energy

By Courtney Tanner   02/11/20  
It’s going to be much more sustainable to light up Rice-Eccles Stadium, the hospital at the University of Utah and all of the classrooms on campus in between.
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Geothermal energy: Drilling a 3,000-meter deep well

Destabilizing the precarious equilibrium at depth with geothermal wells may reactivate the geological layers causing earthquakes. Researchers have studied the seismic activity linked to a geothermal drilling in search of supercritical fluids. They discovered that…
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2020 to become a milestone year for the global geothermal energy sector

By Alexander Richter   01/27/20  
Going into a new decade, geothermal energy is well positioned in the efforts on a global energy transition providing heating, cooling and electricity around the clock, so the International Geothermal Association.
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More Energy Expected To Come From Geothermal In California

By Brooke Ruth, Mark Sauer   01/27/20  
Two new geothermal plants are in the works in the state, one is in the Salton Sea area and the other is in northern California. The growth in geothermal is believed to be spurred by…
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California needs clean energy after sundown. Is the answer under our feet?

By Sammy Roth   01/22/20  
After years of playing third fiddle to solar and wind power, geothermal energy is poised to start growing again in California. Three local energy providers have signed contracts this month for electricity from new geothermal…
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Geothermal Energy Research in Port of Rotterdam Enters Next Phase

Shell Geothermal BV and the Port of Rotterdam Authority are investigating the possibilities for geothermal energy in the Port of Rotterdam’s western section. The two companies have received an exploration permit from the Ministry of…
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How A Climate Change Nonprofit Got Eversource Thinking About A Geothermal Future

By Bruce Gellerman   01/13/20  
Natural gas utilities in Massachusetts are facing an existential crisis: they could be out of business by mid-century. That's because the state's 2008 Global Warming Solutions Act requires emissions from burning fossil fuels — like…
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Geothermal Deal Could Lower Hawaii Island Electric Bills

A Hawaii island geothermal power company that was knocked offline by a volcanic eruption hopes to produce lower cost electricity under a new agreement with a state utility, company officials said.
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Construction Begins on Geothermal District Heating Pipeline in Iceland

Construction of a new geothermal district heating pipeline is underway in rural South Iceland to the small town of Höfn. The pipeline stretches from its source nearly 20 km away.
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Diversifying the Northeast power mix: Is offshore wind + storage key to the region’s reliability?

By Herman K. Trabish   07/02/19  
ffshore wind and battery storage are about to come into the Northeastern power mix in a big way. With more states requiring offshore wind targets, almost 18 GW are mandated to come online by 2035…
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Supercharged geothermal energy could power the planet

By Julia Rosen   10/17/18  
The next generation of geothermal plants will unlock more of Earth's bountiful, underground energy and could allow the technology to finally fulfil its promise
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Geothermal Energy Could Provide All the Energy the World Will Ever Need

By Unni Skoglund   09/16/10  
There is a solution for the world’s insatiable energy needs. It is CO2-free and safe. And it’s located right under our feet. Ever since Jules Verne wrote in 1864 about a trip to the Earth’s…
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