The state of Nevada produces about 10% of its own
electricity via geothermal power plants, the highest state percentage in the
country, although California produces much more geothermal power overall. I got
to spend a few months working in Central Nevada’s Basin and Range province
within the Great Basin back in 1988 when I did my geology field camp. It was an
interesting place, high desert country full of sagebrush, prickly pear
cactuses, a few juniper trees, scorpions, rattlesnakes, lizards, and rocks, mappable
rocks. There were sedimentary sequences, metamorphic rocks, such as quartzite,
and igneous intrusions in the form of dikes and sills.
The new USGS report, which
covers the Great Basin, nearly all of Nevada, and parts of Arizona,
California, Idaho, Oregon, Utah, and Wyoming, is estimated to be capable of
producing about 10% of the nation’s electricity if fully developed. However,
there are several logistical hurdles to that ever happening, including distance
from population centers. Where I did my geology work was in a small former mining town, Eureka. It was 50 miles to the nearest town in any direction. The report estimates that if EGS systems were fully
developed at scale there, they could produce 135 GW of electricity.
Enhanced geothermal systems
(EGS) cultivate heat by drilling into hot and dry rocks, then hydraulically
fracturing those rocks to create an induced fracture network. The third step is
to add water to the fracture network to create a hydrothermal system. According
to the Newsweek article:
“In addition to the mapping effort, the USGS used
artificial intelligence and machine-learning techniques to improve data
modeling and resource estimation speed. The agency said it plans to apply these
methods next in North Dakota, to the Williston Basin.”
Many EGS studies and
assessments have taken place in this region, which has low-permeability rocks
but high heat flows. The FORGE project in NW Utah and Fervo Energy’s other EGS
projects in that area are the only ongoing projects so far, but they have
succeeded in creating enhanced geothermal systems that work as well as or
better than predicted. The new resource assessment focuses on:
“…updated heat flow maps, updated underground
temperature maps, and new methods to estimate, energy extraction efficiency for
different fracture geometries and conversion of thermal energy to electricity.”
They also estimate electrical power production potential
for all areas above 90 degrees Celsius. USGS notes that this is a provisional
assessment, which assumes that technologies will improve over time and perform
as anticipated or projected. They calculated the amount of rock under 6km in
depth with temperatures high enough to produce electricity. The report also
considers potential efficiency and technological improvements that may increase
the current resource estimates considerably. The following efficiencies are
considered:
They note that uncertainty is dominated by the factors of heat extraction efficiency and viable geology. This assessment is an acknowledgment of the likely success of EGS in this region for power production. However, other factors such as deployment costs and O&M costs need to be lowered considerably before any widespread adoption occurs. EGS has operational advantages over conventional geothermal in that issue like well and casing corrosion are less likely than in conventional geothermal.
References
USGS
discovers major energy boost for United States. Theo Burman. Newsweek. May 26,
2025. USGS
discovers major energy boost for United States
Enhanced
Geothermal Systems Electric-Resource Assessment for the Great Basin, Southwestern
United States. U.S. Geological Survey. May 2025. FS 2025-3027: Enhanced
Geothermal Systems Electric-Resource Assessment for the Great Basin,
Southwestern United States — FS 2025-3027
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