By Kay Modi, JHCGA’s Energy Analyst in Residency
New venture capital and US Department of Energy (US DOE) funds through the Inflation Reduction Act (IRA) are advancing the test drilling into deep, hot, dry rock formations to develop the potential for clean geothermal to produce electricity. These projects are making headlines in the energy world in 2023 with successful demonstration projects. The oil and gas (O&G) industry’s development of deep well drilling techniques, horizontal drilling, and fracturing of rock formations (aka fracking) is being applied at depths of 10,000 to 20,000 feet and they are not seeking petroleum resources or natural hydrothermal.
Their objective is to inject pressurized water (or other recoverable fluid) into a hot man-made reservoir and returning the heated water that is higher than 150 degrees C (302 degrees F). Their recovery at the surface may be used to heat steam for turbines and generators that produce electricity at utility scale. Many western areas of the US and other scattered areas have this potential resource for low-carbon electricity from geothermal. These projects could be considered compatible with wind and solar variable resources to stabilize the grid’s growing demand for electricity with the ability to be baseline or dispatchable electricity production.
Geothermal Resources of the US
Above 150 degrees C Shows Large Viable Areas
The new partnerships of O&G drilling companies, university research teams, experts in subsurface characterizations, renewable energy financing, and utility companies are gathered by geothermal development companies. These companies include Fervo Energy, Geothermal Technologies Inc., Sage Geothermal and Eavor that have new visions for low carbon electricity production and have active drilling projects.
Successful demonstrations in Utah, Texas, New Mexico, Nevada, and Europe are laying the groundwork for additional wells and their horizontal drilling with fracturing of the formations at these extraordinary depths. A video by Utah’s FORGE* projects demonstrate the physical effort taken to tap this energy resource. A video by Sage Geothermal illustrates the potential of the drilling programs to construct moderate sized power plants.
Illustration of Horizontal Drilling and Fracturing of Rock Formation for Connectivity
When companies such as Google, Berkshire Hathaway, Pacific Corp, Devon Energy and drilling experts previously employed by the O&G industry combine their efforts to bring an existing energy resource to the forefront of technology, progress is made at relatively faster pace than other renewable energy options. The use of O&G drilling companies and their rigs, readily designed conversions of steam to electricity, and nearby routes to major transmission lines of the grid are essential for the timelines. Colorado revised its O&G commission to improve the permitting process for geothermal projects and Colorado's governor Jared Polis has led the way with a publication in 2023 called “The Heat Beneath Our Feet” for the Western Governor's Association. This publication covers the vast topic and includes conventional hydrothermal.
Software Simulation of Hot Dry Rock Reservoir
The above picture is a software simulation of the potential hot, dry rock reservoir near Milford, Utah. Fervo is scheduling small demonstration plants of 4 to 5 megawatts (MW) of electricity production at their Nevada and Utah locations and larger scale of 400 megawatts by 2028 near Milford. Their wells showed success with the injection of water into formations and the return of heated water through another well. This connectivity is the proof that the rock formation can serve as a man-made reservoir with heat potential for larger scale planning.
A November 7th interview with the CEO of Fervo, Tim Latimer, provides a detailed review of the technology and their plans.
The man-made reservoirs with water injection are called Enhanced Geothermal Systems (EGS) within the industry and they are not without their challenges. The sites chosen need to investigate the following issues:
· seismic activity during drilling and injecting water,
· equipment’s ability to work at high temperatures,
· low permeability (low leakage of the injected water from the man-made reservoirs),
· subsurface mapping to document the size of the formation’s reservoir to sustain a full-scale power plant,
· accessible water supply for the circulation (closed loop enables water conservation), and
· environmental risks.
Obtaining a permit to drill wells is remarkably fast on private lands considering EGS, and the process can be as fast as two months. Federal lands need to revamp their permitting programs to reduce their timeline.
The adaptable designs of power production can use EGS as baseload electricity (such as coal, natural gas, and nuclear) or for dispatchable systems that can effectively adjust for the hourly changes in electricity demand. The man-made reservoirs could be a viable option for energy storage based on theories from Sage Geothermal. The storage capacity of specific reservoirs could be more than 12 hours of the temporary excess of variable wind and solar power production. Some of these storage options (location dependent) also have the potential to increase the temperature of the injected water to generate even more power than diverted to storage. Several wind power farms have the ability to co-locate EGS and take advantage of the transmission infrastructure.
Drilling Test Wells in a Wind Farm, Existing Infrastructure for Transmission
As the drilling programs for EGS provide economies of scale and successful field demonstrations, they expect to be competitive with other renewable energy sources. As large O&G firms join with their own projects and in-house staff, EGS may attract more funding. All involved are lobbying for EGS to become equally supported as a renewable energy source with government funding and private investors. Right now, it is comparing millions for EGS versus billions for wind and solar.
*All links associated with Utah FORGE may be subject to change due to their website updating.
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