Hot, deep,
pressured, and challenging are four words that can describe supercritical
geothermal energy development. New heat records have recently been noted for
drilling into hot rocks in high-enthalpy geothermal, which refers to rocks that
exceed 250 deg Celsius. Rocks as high as 400 deg C have been drilled into
successfully.
Company Mazama touted its
drilling project into the Newberry Volcano in Oregon as the hottest in the
world, but projects in Iceland and now Utah are even hotter. Mazama’s project
is thus far the hottest EGS project involving hydraulic fracturing of dry hot
rock. Mazama plans two wells in 2026, and they think they can drill into and
transport proppant at 400 deg C, which is the plan for this year.
At a temperature of 374 deg
C, water becomes supercritical, changing its form, giving it more energy per
unit of mass, and improving economics. At these temperatures, 40MW per well
pair is achievable, and up to 50MW per well pair is possible. Mazama’s first
power production pilot is planned to be a 15MW power plant. For EGS projects in
supercritical temperatures, fracking is more of a challenge than drilling. This
is because during drilling, the drilling fluid or mud is pumped from the
surface, where it is cool and it cools when it returns to the surface. The
fluids can be cooled by about 200 deg C, which makes drilling more doable.
These hot projects utilize stainless steel frac equipment, which is slightly
more expensive but not overly so.
The Mazama project in Oregon
is using 9-5/8” casing, which allows higher flow rates than the more common 7”
casing wells. Bigger casing is heavier and requires bigger rigs to drill, but
is manageable. Pressures in these wells can be very high, some as high as
18,000 psi. Pressure, like temperature, increases on a regional gradient with
depth. Most wells in the U.S. West are expected to be at about 4000 meters or
12,000 feet in vertical depth. Flow control technology is used to prevent
thermal short circuiting (TSC). This includes the use of sliding sleeves made
out of the same material as the casing, carbon steel.
Corrosion-resistant alloys and titanium could also be used. These are more
expensive but do not affect the total well cost too much.
In a recent Enverus webinar
presented by Blake Wood with questions and input from Enverus’s Graham Bain, it
was noted that Wood thinks existing drilling and frac tools could work at up to
600 deg C. Work is underway to build sensors that can withstand 900 deg C.
Comparing hydraulic fracturing of supercritical geothermal wells to shale
wells, it was noted that geothermal wells drilled into granite are common and
that granite is brittle and fracks as well as shale and sometimes even better.
However, failing downhole components and transporting proppant further out from
the wellbore remain significant challenges. The current process is to drill the
first well and frack it while monitoring the frac with a second well to
determine where frac swarms go, and then drill the second well into the frac
swarms. In the future, simultaneous hydraulic fracturing can improve economics
as it has with shale wells.
Water loss is a big concern
for EGS. This refers to drilling fluids that are lost into the formation during
drilling. Lowering reservoir pressure can lower water loss to the goal of
<1%. For EGS, where there is no existing hydrothermal system and existing
natural fracture network, water loss should be less than in places where there
is.
He mentions a project in
Utah, very close to Fervo’s project, in collaboration with the DOE, which is
also near a conventional power plant. He notes that LCOE for the new project in
Utah is expected to be about $52 per MWh for a first-of-a-kind project. Fervo
is at $91 per MWh with PPAs at over $100 per MWh. The company whose name I
missed from the webinar, and I can’t seem to find online, is talking to
potential buyers and working on PPAs. These projects, as well as those of
Quaise Energy, which I will address later in this post, will get results on
flow rates and power outputs in about 18 months. He suggests that in the coming
years, more supercritical EGS projects will be developed in places like Japan
and the EU, possibly Germany. More research and data acquisition are needed,
including a fiber optic system that can withstand 400 deg C and last for ten
years.
He notes that drilling and
stimulation costs are about the same for wells, but the highest cost part of
these projects is by far building the power plants. He also notes that there is
a bottleneck in turbine production due to the need for customized turbines and
that this is not related to the existing bottleneck on gas turbines.
Single-point of entry with
frac sleeves can control frac directions better than plug-and-perf, as is used
in the oil & gas industry. Frac stage spacing = 12-13 meters (36-39 feet),
which is significantly closer than stage spacing in oil & gas, which is on
the order of 100-250 feet. This increases frac cost but is acknowledged as a
need.
Quaise Energy Successfully Tests Its Millimeter Wave
Drilling Technology
Quaise Energy is developing a
new kind of drilling into hot rocks via its millimeter wave technology, which
vitrifies the rock as it drills, theoretically making that vitrified rock into
a de facto casing for the well. It utilizes a device known as a gyrotron that
produces energy waves similar to microwaves and lasers, but on a different part
of the spectrum. The company successfully tested its drilling technology
recently in Texas.
According to the MIT Energy
Initiative:
“Quaise Energy, an MIT Energy Initiative (MITEI) spinout
developing geothermal energy, hosted the first of several live public
demonstrations of their drilling technology this September at Marble Falls, TX.
The company proved their technology can drill into the granite outcrop in a
quarry with pure energy instead of physical drilling bits.”
“In July, Quaise successfully drilled a 118-meter hole
in the field—outside of what was previously controlled experimental conditions.
The September demonstration showed that they can drill through some of the
hardest rock in the world at a rate of up to five meters per hour. According to
Henry Phan, the vice president of engineering at Quaise, today’s commercial
operations’ average drilling rate is a tenth of a meter per hour through
granite.”
In its demonstrations, the
company proved that it could vaporize rock using high-frequency electromagnetic
waves, drilling 387 feet (118 meters) into solid granite without any physical
contact. The next goal for the months ahead is to drill deeper and faster.
Quaise is also working on
Project Obsidian, also near the Newberry Volcano in Oregon, where depths to hot
rock are shallow. According to Power Magazine’s Darrel Proctor:
“Geoffrey Garrison, vice president of Operations at
Quaise Energy, said his company “is actively developing Project Obsidian in
Oregon, the world’s first superhot geothermal power plant. The area has been
continuously studied for decades, with superhot geothermal temperatures
relatively close to the surface. Project Obsidian is currently undergoing
several phases of construction and development before moving into power plant
construction and operation. We expect the facility to be fully operational and
generating power [eventual output would be 250 MW] for the local grid by 2030.”
According to the webinar,
Quaise’s technology is fascinating but may not be needed if other methods can
tap hot rock. However, in order to drill into even hotter rock, say 450-1000
deg C, current rotary drilling will not suffice.
References:
Supercritical
Geothermal: Drilling Into the Hottest Rock on Earth: Innovation Underground –
Webinar by Enverus. April 1, 2026.
MITEI
spinout Quaise Energy successfully demonstrates their geothermal energy
drilling technology in the field: Company’s technology could unlock clean,
renewable geothermal energy using pure energy. Kelley Travers. MIT Energy
Initiative. November 3, 2025. MITEI spinout Quaise Energy successfully demonstrates their
geothermal energy drilling technology in the field | MIT Energy Initiative
US
firm’s record-breaking drill taps granite 387 feet deep to unlock geothermal
power: The live demo showcased the first field use of this non-contact drilling
method. Georgina Jedikovska. Interesting Engineering. September 18, 2025. US firm drills record 387 feet into granite with millimeter
wave system
Geothermal
energy turns red hot: MIT Energy Initiative symposium maps path to tap the
planet’s heat-rich rocks for clean power at scale. MIT Energy Initiative. Leda
Zimmerman. March 26, 2026. Geothermal energy turns red hot | MIT Energy Initiative
Geothermal’s
Rise a Hot Topic Worldwide. Darrell Proctor. Power Magazine. April 1, 2026. Geothermal's Rise a Hot Topic Worldwide
Generation
and Distribution: Part 9. Quaise Energy March 16, 2026. Generation and Distribution: Part 9 | Quaise Energy
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