Sustainable energy continues to grow as a focus for reliable, affordable, and secure energy as seen from the past year of papers reviewed for this feature. Three primary areas are being reported on heavily: carbon use for enhanced oil recovery (EOR), geological hydrogen discovery, and critical minerals including rare earth elements and advanced materials from the subsurface. Another takeaway, meanwhile, is that artificial intelligence and machine-learning techniques continue to promote and support the delivery of sustainable energy.
Carbon use, such as CO2 for EOR, has been in practice for multiple decades, and many papers cover the mechanisms, fluid dynamics, various scales of laboratory tests and experiments, upscaling for well- and reservoir-level studies, modeling and simulations, field development and operations, observations, and lessons learned. On the flip side, what are the risks and potential for failure? EOR with a high solvent-utilization factor has seen success in the avoidance of corrosion, injectivity loss, and well-integrity problems. Multiple papers address these challenges. Paper SPE 224770 highlights a drilling and completion approach that tests various casting materials by introducing fault tree analysis and Bayesian network methods to evaluate the probability of failure and rank the risk levels of various contributing factors to improve the chances of success.
Hydrogen, particularly geological hydrogen, seems to be receiving increased attention in various geological environments and from sources both hydrocarbon- and nonhydrocarbon-related. Studies cover its potential from various global regions, onshore and offshore, and naturally occurring or stimulated. Most of these papers fall into the category of mapping and resource assessment at this early stage, while some specific research focuses on stimulation mechanisms and processes, as well as some risks, as detailed in paper SPE 224210. Various data-analytics and machine-learning techniques are also used to evaluate the data and infer correlations.
Critical minerals and rare earth elements have been found in coproduction in streams produced during hydrocarbon and geothermal extractions. Lithium is an example discussed intensely worldwide. Paper OTC 36361 provides a review of such coproduction opportunities. While the paper emphasizes this coproduction in certain global regions, it also mentions specific areas of initial assessment. Furthermore, the sources and mechanism of lithium enrichment from oilfield brines are also discussed.
Overall, gaps remain to be filled from field-scale research on viability and value addition for major production streams to improve economics and facilitate affordable energy.
Summarized Papers in This July 2026 Issue
SPE 224770 Study Assesses Integrity, Corrosion Risks of CO2 Injection in Oil-Recovery Operations by Fei Zhao, Yan Ding, and Congyue Lv, CNPC, et al.
SPE 224210 Predictive Analytics Reduce Exploration Risks for High-Potential Geologic Hydrogen Discoveries by Semaa Alessa, SPE, and Lori A. Hathon, SPE, University of Houston, and Hanaa M. Ali, University of Basrah, et al.
OTC 36361 Direct Lithium Extraction Provides Pathway for Energy Transition and Resource Recovery by Mei Quen Yew, Santosh Mishra, and Afifah Azmi, Petronas, et al.
Recommended Additional Reading
OTC 37197 Certification of Carbon Intensity for Geological Hydrogen (Methodological Framework and Regulatory Benchmarks for Bankable Projects) by Veronica Vaca, independent researcher, et al.
SPE 225580 Investigation of Wellbore Flow and Transport Dynamics During Geological Hydrogen Production by Yuxing Wu, Southern Methodist University, et al.
SPE 227940 Can Stimulated Geological Hydrogen Generation Systems Be Circular? by N.M. Angelina, Texas A&M University, et al.
OTC 36953 Assessing the Economic Viability of Stimulated Geological Hydrogen in Offshore Settings by M.A. Oestriecher, Texas A&M University, et al.
SPE 227484 A Comparative Review on the Major Recourses and Technologies for Lithium Extraction by Weiyao Yan, Aramco Americas, et al.
SPE 227608 Lithium Potential in Saudi Arabia—An Initial Assessment by Maria Alejandra Ortiz, King Abdullah University of Science and Technology, et al.
Guoxiang “Gavin” Liu, SPE, is a general engineer at the National Energy Technology Laboratory (NETL), US Department of Energy, where he focuses on cost and economics analysis of energy systems and applies his subsurface expertise to fossil and sustainable energies, including oil and gas, hydrogen, and geothermal, as well as carbon management. Liu holds a PhD degree in environmental engineering from West Virginia University, an MS degree in computer science from Leiden University in the Netherlands, and a BS degree in chemistry and computer management from Yunnan Normal University. Before holding his current position, Liu served as team lead and senior engineer supporting the NETL mission and energy delivery by working with a multidisciplinary team of scientists and engineers. Previously, he worked for 5 years in the oil and gas industry. Liu has authored or coauthored more than 100 publications, including patents, books, journal articles, conferences, technical reports, and presentations.
