A common ingredient – ​​salt – could play a major role in the energy transition to low-carbon energy sources. Salt tectonics can play a role in important energy transition technologies, such as energy storage as gas in salt caverns, CO2 storage and geothermal energy. A new one highlights the development potential in salt basins, such as hydrogen storage caverns, CO2 storages for porous media and improved geothermal energy potential. Exploiting these resources requires a better understanding of the internal composition, geometry and evolution of salt structures and their surrounding sediments. This new insight will help optimize design, reduce geotechnical risks and improve the efficiency of energy transition technologies.

Researchers at the University of Texas at Austin’s Bureau of Economic Geology have discovered how large underground salt deposits could be used as hydrogen storage tanks to transfer heat to geothermal facilities and influence CO2 storage. It also shows how industries with current salt expertise, such as solution mining, salt mining, and oil and gas exploration, can help.

Lead author Oliver Duffy, a research scientist at the agency, said: “We see potential in applying knowledge and data gained from many decades of research, hydrocarbon exploration and mining in salt basins to energy transition technologies. Ultimately, a better understanding of how salt behaves will help us optimize the design, reduce risk and improve the efficiency of a range of energy transition technologies.”

Study co-author Lorena Moscardelli, the chief of the agency’s State of Texas Advanced Resource Recovery (STARR) program, said: “These structures and their surrounding geology provide a number of opportunities for energy development and emissions management.” Salt has a significant impact on the formation of the earth’s underground layers. Geological processes easily squeeze it into complex and massive deposits, with some underground salt formations higher than Mount Everest.

She also said, “The co-location of above-ground infrastructure, the potential for renewable energy, favorable underground conditions and proximity to markets is key to underground hydrogen storage plans. STARR is currently focusing on emerging energy opportunities in West Texas, involving hydrogen and carbon capture, utilization and storage potential for the region.

According to agency director Scott Tinker, several options should be carefully explored as salt plays a role in creating new sources of energy. He said the agency’s investigators are essential to this.

He said, “Office researchers have been studying subsurface salt formations for decades. For their role in hydrocarbon exploration, as part of the Strategic Petroleum Reserve, for the storage of natural gas, and now for their potential to store hydrogen. That’s the remarkable thing about great research. It just keeps evolving, improving and finding new uses.”

Oil refineries and the petrochemical industry have successfully used salt domes as storage containers for hydrogen. The paper suggests that these salt forms could be used to store hydrogen for power generation. In addition, the porous rock surrounding it can be used as a long-term storage place for CO2 emissions. The study discusses the potential benefits of combining CO2 storage and ‘blue hydrogen’ synthesis from natural gas. The CO2 emissions from the production process can be sent to nearby rock for long-term storage, while the hydrogen is sent to salt caverns.

The Texas Gulf Coast is particularly suited to this form of combined production and storage, the researchers say, with its many salt domes surrounded by porous sedimentary rock.

The study also looks at how salt can increase the use of advanced geothermal technologies. The researchers show how industry can harness salt’s ability to easily transport heat from warmer underlying rocks to generate geothermal electricity, even as the industry is still in its infancy.

Magazine reference:

  1. Oliver Duffy, Gillian Apps, et al. The role of salt tectonics in the energy transition: an overview and future challenges.Tektonika. DOI: 10.55575/tektonika2023.1.1.11