Enhanced Geothermal Energy – Two Current Approaches

Enhanced geothermal energy – Two current approaches

Geothermal energy, which involves the harnessing of heat, whether from close to the earth’s surface or from deep within, offers the promise of being a clean, constant and reliable power source. Unlike solar and wind power, which is intermittent unless paired with batteries, geothermal might be viewed as an infinite source of energy. 

Think of it as the world’s largest combined energy source AND battery. It operates 7/24/365 and is unaffected by weather conditions. When used with a simple, ground-source heat pump to provide efficient heating and cooling, geothermal, in volumes sufficient to do the job, may be found anywhere from just four to six feet below ground level for horizontal ground loops, to about one hundred to four hundred feet down for vertical systems. 

The ground at these depths provides the heat source needed for the highly efficient operation of heat pump-based HVAC systems during the winter months, and functions as the heat “sink” when the system reverses in order to provide building cooling during the summer months.  As drilling penetrates deeper into the earth, the increase in temperature enables the use of far more sophisticated technologies.

This article looks at the innovative technologies being developed and utilized by two companies – Fervo Energy and Quaise Energy

Fervo Energy, Houston TX. 

Fervo was founded in 2017 by people having extensive experience in drilling and hydraulic fracturing (fracking) in the oil and gas industry.  They left their jobs in the fossil fuel industry and set up a geothermal business to apply what they had learned there in the clean energy sector.

In 2021 Fervo partnered with Alphabet, the parent company of Google, with the goal of both parties being that Fervo could provide green electricity for the cooling of Alphabet’s data centers in the Las Vegas area.  The three goals for Fervo’s power plant were; sufficient and uninterrupted power; green-sourced; and nearby.  In 2023 Fervo Energy announced that their first pilot geothermal plant, in Nevada, was successful in generating 3.5 megawatts of baseload power.

Fervo’s co-founder and CEO Tim Latimer cites the need, in the U.S. and the world for more electrical energy.  He points to the rising demand for electricity from Artificial Intelligence, from the proliferation of data centers, and from the ever-growing number of electric vehicles.  Fervo’s plan and actions to help meet this demand is by EGS – Enhanced Geothermal Systems – by combining fracking and geothermal technologies.  Conventional geothermal drilling has until now been limited to vertical wells. 

In the Fervo system, the addition of horizontal wells, which connect the vertical wells, increases heat mining efficiency by maximizing contact of the circulating water with hot rock, creating artificial reservoirs in hot, dry areas, and allowing multiple wells from one spot, reducing the power plant’s footprint.  They act as pathways to circulate water, extracting heat for continuous power.  This advanced drilling and reservoir management, borrowed from the oil and gas industry, makes geothermal energy more scalable and cost-effective in more locations.

Fervo’s ability to connect two or more deep-bore vertical geothermal wells with one or more horizontal wells offers many benefits:

• It provides access to vast volumes of hot rock.
• This access creates extensive fracture networks for massive heat transfer to water brought from the surface.
• It improves the connectivity between injection wells and production wells, which enables higher flow rates and minimizes temperature variations.
• It significantly lowers costs through repeatable processes, leading to more productive, economically viable, and consistent baseload geothermal power generation.

Using state-of-the-art traditional drilling equipment, Fervo aims to achieve depths of up to 15,000 feet – about 2.8 miles – into the ground, accessing hot – but not what is today considered superhot – rock.  Temperatures at that level can be around 270 degrees celsius/520 degrees Fahrenheit.

In June 2025 Fervo announced the successful drilling and opening of its Sugarloaf geothermal well in Utah.  It was drilled to a true vertical depth of 15,765 feet, and achieved its goal in the rock temperatures it was hoping to find at that depth.  The Sugarloaf well was drilled in just 16 days, with an average rate of penetration of 95 feet per hour.  Sugarloaf is part of Cape Station Phase 1, the company’s first full-scale commercial development.  The positive results of this accomplishment have customers lining up. 

Fervo recently signed a pair of 15-year Power Purchase Agreements (PPAs) with Southern California Edison totaling 320 megawatts.  Other deals: a 48-megawatt contract with Clean Power Alliance; 20 megawatts with California Community Power; and 31 megawatts with Shell.

Quaise Energy

Quaise is based in Cambridge MA, and is pioneering in the development of ultra-deep geothermal energy by using a unique millimeter wave (MMW) drilling technology.  It is best described as a high-powered microwave.  Rather than simply drilling mechanically through rock, and reducing it to small fragments, MMW vaporizes rock in order to easily access Earth’s heat anywhere, not just in the usual geothermal hot spots.  The company’s aim is to provide baseload, terawatt-scale clean power at existing grid-scale power plants by enabling them to convert from coal or gas to geothermal energy, anywhere in the world.

The Quaise breakthrough started as research at MIT, at its Plasma Science and Fusion Center.  MMW drilling uses high-powered vacuum tubes called gyrotrons that melt and vaporize the hardest rock, allowing for drilling deeper and more efficiently than can be achieved by conventional methods, especially in hard, hot rock.  Quaise’s scientists believe that its MMW technology will soon enable it to drill to depths of up to 20 kilometers, or about 12.5 miles.  In mid-2025 Quaise, using  MMW – also known as gyrotron technology – successfully drilled a 118-meter hole at a granite quarry in Texas, the greatest distance granite has ever been drilled.  The company soon hopes to begin to show what it is actually capable of doing using this technique.

Quaise advocates for a hybrid approach to the drilling of ultra-deep geothermal wells.  It envisions two separate drilling stages – the conventional stage and the MMW stage.  The conventional stage is standard rotary drilling to penetrate the first mile or two of soil and sedimentary rock.  Once the drill reaches the harder, so-called basement rock, the system switches to the MMW/gyrotron stage in order to continue to drill down to the depths where conventional metal drill bits would melt.

The kind of geothermal drilling a company like Quaise Energy is involved in is sometimes called “enhanced” geothermal, or EGS, although Fervo Energy uses this term for its work as well.  EGS is used to indicate the greater drilling depths being achieved, and the increased water and steam temperatures found at these levels.  EGS has the potential for providing both high-level industrial process heat, as well as the temperatures that enable the production of grid-scale electric power.  Quaise people point out that, as deeper drilling results in higher temperature steam, these high temps in turn enable higher operating efficiencies at the power plant.

Enhanced geothermal enables the creation of underground reservoirs of hot, dry rock, rather than geothermal drilling being limited, in the traditional manner, only to the few locations where hot water is already present.  Quaise’s technology instead penetrates down to where dry but super-hot rock is found, injects water into these spaces, then brings the superheated water/steam to the surface. 

One of the side benefits of the Quaise system is that its MMW drilling technique creates a natural glass lining in its drilling hole, by vaporizing the rock and vitrifying the molten remains into the borehole wall.  This has two positive results.  It provides structural stability and it prevents fluid inflow, unlike traditional drilling that requires and relies on the installation of steel or cement casings.  This self-casing process, where melted rock solidifies into a glass layer, protects the waveguide, enables drilling in harder rock, and offers a faster and more cost-effective path to ultra-deep, energy-rich geothermal resources. 

The rest of the atomized rock, in dust form, not needed in creating the well’s glass lining, is brought to the surface by circulating a pressurized purge gas, such as air, argon, or nitrogen, down the well.  This process sweeps the excess vaporized rock dust up the space between the drill string and the wall of the borehole to the surface.

Quaise Energy’s scientists and executives believe their MMW drilling technology will enable the building of its first superhot geothermal power plant in 2028.  It hopes that in mid- to late-2026 it will have completed a 100 megawatt version of what it then hopes to expand toward grid scale beginning in a couple of years.

Other articles by Mark Dullea:

Rooftop Agrivoltaics: Is It Here Yet?