Executive Summary:
Energy Transition

The energy transition represents a challenge to massively reduce the levels of greenhouse gas emissions globally while maintaining living standards and economic prosperity. This entails shifting energy production to renewable or low-carbon sources, while potentially also sequestering residual CO2 emissions from fossil-based energy sources. In the United States, a growing list of technologies focused on the subsurface are being investigated and deployed, including: 1) extraction and storage of geothermal energy and hydrogen, 2) geologic sequestration and possibly mineralization of CO2, and 3) recovery of critical minerals like lithium, nickel, copper, and rare-earth elements for electrification and energy storage. Despite the interest in these alternative resources, the high costs of exploration and pilot studies, along with unknown environmental impacts and negative externalities affecting host communities, remain major barriers to the widespread implementation of these subsurface initiatives. Research to overcome the challenges could help improve the prospects for the successful use of these resources and attract early-career geologists to train and develop the skills required for energy transition technologies. Ultimately, this could help to bridge a key gap in the geoscience workforce.

Continental Scientific Drilling (CSD) projects are unique in their technical ambition and ability to deliver the critical subsurface materials and data needed for foundational research that must underpin the energy transition in the United States. As a sustained community-driven research organization, the CSD facility’s involvement in energy transition research could generate benefits beyond its roles in drilling, data collection, and data management, through transparency, outreach, and public engagement. 

Research drilling is vital to support and improve the development potential and exploration success of non-petroleum resources. It is essential that the basic research community intentionally and deliberately evaluate geologic models and concepts related to natural hydrogen and critical minerals in the subsurface, along with energy and CO2 storage potential. Geoscientists must also look ahead by years to centuries to anticipate how the subsurface environment will change while resources are extracted. An understanding of how changing pressure and fluid properties may induce earthquakes, contaminate groundwater, or generate other environmental impacts must advance so as to mitigate those risks and address societal concerns. Predictions of mineralization, dissolution, or changes to permeability within reservoirs can be important to understand to optimize resource development. 

Even though the goal of the energy transition is to attain an energy mix that promotes a healthy and prosperous society, drilling into the Earth is perceived as a process to extract resources that cause harm. While conducting research to answer scientific questions, energy transition research projects can demystify for the public the link between the energy extracted beneath our feet and the energy delivered at the light switch. 

Scientific questions that will require deep subsurface drilling in the next decade 

1. Energy Transition Resource Science: What are the mechanisms (physical, chemical, microbial) that lead to the enrichment of elements critical to the energy transition in both ancient mineral systems and active hydrothermal systems? 

In areas where deep drilling is sparse, subsurface conditions or properties favorable for geothermal energy, critical mineral enrichment, or hydrogen accumulations are poorly documented. Even in well-explored basins and mineral districts, the diagenetic or epigenetic mechanisms that enrich critical minerals are not well understood. A better understanding of the transport and trapping mechanisms for critical minerals in ore-forming mineral systems and geologic hydrogen accumulations would hasten rational extrapolation from known exploration targets to untested areas. Improved understanding of key mechanisms integrated into broader geological models will improve prediction of where to find these resources. More specific goals include: 1) understanding where critical minerals are distributed in ore-forming mineral systems, 2) understanding fluid flow in deep crustal environments particularly with respect to effective permeability, pressure, and water-rock interactions, and 3) investigating the role of the deep biosphere in the genesis, preservation, and consumption of critical minerals and geologic hydrogen.

2. Potential Human Hazards: Relative to the hazards involved with the extraction of subsurface energy or energy materials, what features of the in situ rock system enhance or diminish the risks associated with these activities? Similar hazard uncertainties exist for underground storage of energy materials or CO2. What attributes of the rock system are critical to understand and quantify in order to improve predictability and mitigation of the hazards related to development?

Induced seismicity, groundwater contamination, sinkhole formation, and surface deformation are among the known outcomes of subsurface development, whether by extraction, injection, or cycling of fluids. Mitigation of those risks remains a central challenge, yet failure to mitigate could undermine public acceptance of potentially valuable projects. 

In continental crust, insufficient understanding of stress and permeability hinders practical development of technologies for widespread extraction of geothermal heat or for sequestration of CO2. A better understanding is needed of how the near-field crust immediately reacts to changes in pore pressure, temperature, geochemistry, and resultant thermo-chemo-poroelastic effects. It will also be important to see how the far-field crust is affected, and how the risks for induced seismicity and contamination change through project time. Additionally, assessing the integrity of underground salt caverns is key to the success of future hydrogen energy strategies. Scientific goals that are steps toward understanding these risks are to determine the spatial distribution and temporal evolution of stress and permeability with depth, and the intertwined relationships with temperature, lithology, fault and fracture systems, rock fabric, flow dynamics, and mineral dissolution and precipitation.

3. Subsurface Geological Impacts: For each type of subsurface production system under operational conditions, what will be the impacts on the subsurface environment (e.g., reservoir quality, fluid flow interconnectivity, recoverability, thermal breakthrough time)? 

Moving hot fluids, hydrogen, carbon dioxide or other gasses into and out of subsurface reservoirs can disturb rock and fluid equilibria. What will be the sequential changes and the rates of change? Will those changes improve recovery potential or negatively impact the viability of the system over the anticipated lifecycle of resource extraction or injection? How does the deep biosphere influence the accumulation and extractability of resources and how will the biosphere be affected by resource extraction? Answering these questions requires baseline geological and geochemical data and in situ evaluation of changes to the rocks and fluids. Today there are few testing grounds for evaluating these subsurface activities. 

Priority Opportunities

1) Borehole observatories

Great strides in the energy transition related to subsurface characterization, rock-fluid interaction, and hazard mitigation can only occur by having access to and studying the rocks and fluids in situ over extended time periods. Subsurface borehole observatories are needed in multiple environments targeted for energy-transition subsurface projects to enable monitoring as well as experimentation under real conditions. These need to be well instrumented and with equipment/facilities for repeated extraction of fluids and solids. 

2) Drilling to characterize resource systems

Drilling programs are needed that target the key elements of mineral and hydrogen systems in order to constrain the physical and chemical processes that govern the ultimate accumulation of critical minerals (e.g., platinum-group elements, tellurium, and lithium) and geologic hydrogen. 

3) Legacy collections and archived borehole data

The filling of some key knowledge gaps for energy transition materials (e.g., critical minerals, heat, hydrogen, and CO2 sequestration materials) can advance rapidly by exploiting materials in legacy collections of core and cuttings and with archived borehole data. Examples include research to better characterize the heterogeneity of ore systems, critical mineral potential of mine waste, and to evaluate cross-scale heterogeneity of key properties (e.g., mineralogical, chemical, or physical), or for experimentation.

4) Public engagement

CSD-enabled projects draw the attention of the public and provide unique opportunities to engage the public in scientific discovery. Allowing public access to the data collection and analysis process permits interaction and engagement using fact-based data to explain the challenges facing the nation’s energy future.

Suggested Citation

Jordan, T., Birdwell, J., Case, G., Douds, A., Eastman, K., Ellis, G., Ghassemi, A., Hayman, N., Jones, M., Lamadrid, H., Lautze, N., Malin, P., Nash, S., Richardson, C., Trela, J., Shervais, J., Vanden Berg, M. 2024. Energy Transition: Science Planning for Continental Drilling and Coring 2024.  https://sites.google.com/umn.edu/csdscienceplanning/home/energy-transition-executive-summary

Energy Transition Working Group

Justin Birdwell, United States Geological Survey

George Case, United States Geological Survey

Ashley Douds, Indiana Geological and Water Survey

Kyle Eastman, Montana Bureau of Mines and Geology

Geoff Ellis, United States Geological Survey

Ahmad Ghassemi, University of Oklahoma

Nicholas Hayman, Oklahoma Geological Survey

Matthew Jones, United States Geological Survey

Terry Jordan, Cornell University

Hector Lamadrid, Oklahoma University

Nicole Lautze, University of Hawaii

Peter Malin, Duke University

Susan Nash, American Association of Petroleum Geologists

Carson Richardson, Arizona Geological Survey

Jarek Trela, Illinois State Geological Survey

John Shervais, Utah State University

Michael Vanden Berg, Utah Geological Survey

Energy Transition Community Editors

Andrew Barbour, United States Geological Survey

Sally Benson, Stanford University

Lauren Birgenheier, University of Utah

Latisha Brengman, University of Minnesota Duluth

Brett Carpenter, University of Oklahoma

Nicholas Davaztes, Temple University

Patrick Dobson, Lawrence Berkeley National Laboratory

John Eichelberger, University of Alaska Fairbanks

Derek Elsworth, Penn State University

John Farrell, U.S. Arctic Research Commission

Patrick Fulton, Cornell University

Kellen Gunderson, Projeo Corporation

Jesse Hampton, University of Wisconsin Madison

Franek Hasiuk, Sandia National Laboratory

Adam Hawkins, Cornell University

Simon Jowitt, University of Nevada Reno

Amanda Kolker, National Renewable Energy Laboratory

Stephen Laubach, University of Texas Austin Bureau of Economic Geology

Yaoguo Li, Colorado School of Mines

Alicia Lindauer, United States Geological Survey

Maria Mastalerz, Indiana Geological and Water Survey

Stephanie Mills, Utah Geological Survey

Carolina Muñoz-Sáez, Cornell University

Karin Olson Hoal, Cornell University

Kristine Pankow, University of Utah

Ben Parrish, California Geological Survey

Anine Pedersen, Geothermal Rising

Sarah Ryker, United States Geological Survey

Seth Saltiel, Cornell University

Adam Schultz, Oregon State University

Rebecca Stokes, United States Geological Survey

Alexis Templeton, University of Colorado Boulder

David Wang, United States Department of Energy

Doug Wicks, United States Department of Energy

Colin Williams, United States Geological Survey