pwr_april-2024 - 22

GEOTHERMAL POWER
the world); Pohang in South Korea; Hijiori
and Ogachi in Japan; and the Habanero
project in Australia. Only a few EGS projects
are currently operating: the 1.7-MW
Soultz-sous Forêts in France; a 1-MW
installation in Groß Schönebeck in Germany;
the 27.5-MWth Rittershoffen Geothermal
Heat plant in the French Upper
Rhine Graben; and Google and Fervo's
recently opened Project Red.
A key source of seemingly new optimism
for EGS-in the U.S., at least-
stems from assessments unveiled in
January 2023 by the National Renewable
Energy Laboratory (NREL) that suggest
there is tremendous new EGS potential
compared to GTO's 2019-issued GeoVision
study. NREL posits that near-field
EGS resource capacity could hover around
28 TW, while deep EGS holds a potential
resource capacity of up to 7.5 TW.
NREL's findings also point to potentially
dramatic improvements in the costs
of deployed EGS resources. Though the
lab cautions that these vary heavily depending
on geothermal resource quality
and geography, as well as variations in
demand and cost, it sets the range for
EGS installed levelized cost of electricity
(LCOE) from " a little over $30/MWhe
to just under $70/MWhe. " If cost reductions-of
up to 20%-are achieved
in average drilling costs and increased
well productivity by 2035, the capacityweighted
average LCOE of all developed
deep-EGS resources could hover at
$45.9/MWhe and $45.6/MWhe by 2050,
the lab projects.
That analysis, notably, informed the
DOE's September 2022-announced EGS
Earthshot, one of eight research, development,
and demonstration initiatives
launched by the Biden administration to
accelerate breakthroughs for emerging
technologies. The EGS Earthshot sets a
target to reduce the cost of EGS by 90%
to $45/MWh by 2035.
The goal, by all measures, is an ambitious
one. But according to the GTO, it
is achievable. " The $45/MWh target is
founded in technology improvements-
primarily reductions in drilling and
stimulation costs, and increases in well
productivity and production well flow
rates-as well as larger power plants and
studies to better find and characterize
shallower, higher-quality EGS resources, "
GTO said. While many of these improvements
are " aggressive, " several of them
are already happening, it noted.
New Technical Breakthroughs
A long-standing challenge that has under22
scored
any progress for EGS has been to
develop reservoir fracture networks that
can deliver high hydraulic conductivity
and avoid thermal short-circuiting. While
the geothermal sector began to make
progress as an industry in the 1960s, " all
the wells drilled by the geothermal community
for electricity and for EGS in the
past are essentially vertical, " Dr. Joseph
Moore, Utah FORGE managing principal
investigator, explained to POWER. And,
while EGS projects have been built all
over the world, " none of them produced
commercial flow rates, " ideally of up to
600 gallons per minute (gpm), he said.
Taking a page from the oil and gas
industry's horizontal drilling techniques,
FORGE pioneered the first well with a
high angle of deviation using a uniquely
developed drill bit. It has since made
quick progress. Between October 2020
and February 2021, it drilled an injection
well, shattering expectations with drilling
operations that finished 62 days ahead of
schedule. Following stimulation activities
in three stages, it began drilling the production
well in April 2023. In June 2023,
a University of Utah assessment indicated
connectivity between the injection
and production well pair.
An Accelerated Learning Curve
According to GTO, FORGE's demonstrations
have been monumental for EGS.
FORGE demonstrated " average on-bottom
drilling rates exceeding 71 feet per
hour in 2022, " it noted. And now, at least
one commercial firm-Fervo Energy-is
leveraging learnings gleaned at FORGE
alongside years of its own research and
development to add to the remarkable
progress, it noted.
In July 2023, Houston-based Fervo
reported that Project Red-a nearfield
EGS well pair drilled within a high-temperature,
hard-rock geothermal formation
in the Blue Mountain geothermal
field in Nevada-achieved lateral lengths
of 3,250 feet, reaching a temperature
of 376F. It also proved controlled flow
through rigorous tracer testing. The pioneering
3.5-MW EGS developed with
Google reportedly began producing power
in November 2023 (Figure 2).
Fervo also achieved several other
milestones last year. In the summer of
2023, it broke ground on its first greenfield
development in Milford, next to
FORGE-a project that the DOE recently
selected as a federal pilot demonstration.
The project will aim to produce at
least 8 MW of power from three wells at
the greenfield development.
www.powermag.com
Drilling also began in June 2023 at
Fervo's next EGS project, the 400-MW
Cape Station, in Beaver County, Utah,
which is planned to be completed by
2028. By February, Fervo reported the
project had already successfully drilled
one vertical and six horizontal wells
in the high-temperature deep granite
rock. " Though Cape wells are hotter
and over 2,100 feet deeper than Project
Red wells, Fervo drilled its fastest Cape
well in just 21 days, a 70% reduction in
drilling time from Fervo's first horizontal
well drilled at Project Red in 2022, " the
company noted.
Fervo said its results at Cape Station
stem from an increased rate of penetration-of
an average 70 feet/hour-and
the life of its drill bits. The drill bits, made
of
polycrystalline diamond
compact
(PDC), are " typically deployed in shale
basins to cut through hard, abrasive
granite, while mud coolers counteracted
high subsurface temperatures that have
historically derailed geothermal exploration, "
it noted. More crucially, drilling efficiency
has resulted in significant cost
reductions. Fervo has reported drilling
costs across the first four horizontal
wells at Cape fell from $9.4 million to
$4.8 million per well.
The triumphs at FORGE and by Fervo
signify " multifold increases in geothermal
drilling rates of just a couple of years
ago, " the GTO said. " Fervo Energy's drilling
rates already exceed DOE and National
Renewable Energy Laboratory's
2035 'most likely scenario' (under the
moderate Annual Technology Baseline
scenario-50 feet/hour), with learning
rates [Figure 3]-the speed at which
they can bring down costs-ahead of
DOE's most aggressive estimates. "
2. Project Red, co-developed by Fervo Energy
and Google through a partnership forged
in 2021 under the " world's first corporate
agreement to develop an enhanced geothermal
power project, " in November 2023 began
supplying power to the local grid that serves
Google's data centers in Nevada. Courtesy:
Fervo Energy
POWER | April 2024
http://www.powermag.com
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