Comments: Geothermal Brines and Ocean Depths Hold Potential for Lithium
Authors: Boschee Pam 
Published: August 2024

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OTC 35088 presented a direct lithium extraction (DLE) technology based on electrodialysis, developed by Alma Energy and The University of Texas at El Paso. This technology uses ion-selective membranes to extract lithium from geothermal brines and is described as also potentially producing green hydrogen, fresh water, and sequestering CO2.
The technology leverages chlor-alkali electrodialysis, a method using an electric field to separate ions through membranes, adapted for DLE from natural geothermal brines. The proprietary selective membrane system separates lithium from other brine components, producing battery-grade lithium carbonate or lithium hydroxide.
The coauthors wrote that the process doesn’t require chemical reagents, fresh water, or large land areas. It can operate in conjunction with geothermal power plants, using onsite energy and hydrothermal brines, making the process self-sustainable.
DLE has a limited operational footprint and reutilizes existing wells and subsurface data, making it an efficient use of established oil and gas infrastructure. They add that DLE is compatible with the co-production of resources and can extend the lifespan of declining oil and natural gas wells in mature hydrocarbon basins, offering new opportunities for local workforces by repurposing resources from the oil and gas industry.
The modular design of the geothermal DLE solution is centered around a thermal reservoir with a temperature of approximately 330ºF (165ºC). Such a reservoir is projected to produce 100,000 bbl of fluid per day, which is then utilized by an 8-MW binary power plant. The power plant operates with a thermal efficiency of 13% and a capacity factor of 90%, generating roughly 178,800 kWh of electricity daily.
Of the total electricity produced, approximately 50% to 67% is used for on-site operations, which include running pumps, managing binary facilities, and powering the downstream electrodialysis needed for DLE. The process is expected to produce between 2540 kg and 4795 kg of lithium carbonate equivalent per day.
Alternatively, the DLE technology can be used in standalone mode with an external energy supply, allowing its use in areas beyond the established resource basins in the western US, contingent on whether chemical and/or thermal characteristics of the brine are met.
The authors expect the integration of these processes to deliver an internal rate of return between 20 and 33%.

Oxygen-Generating Polymetallic Nodules Deep in the Ocean
Recent research published in Nature Geoscience reported that rock-like polymetallic nodules (PMN) on the deep seafloor can generate oxygen through electrochemical processes, similar to a battery’s electrolysis.
This phenomenon occurs at depths from 12,000 to 13,000 ft below the surface in an area called the Clarion-Clipperton Zone of the central Pacific Ocean and provides a new perspective on how oxygen might have been available in early Earth environments—and potentially offers another source of lithium.
Sunlight cannot penetrate to this depth to promote photosynthesis, but oxygen was reported to be abundant in the CCZ.
The presence of these oxygen-generating nodules has implications beyond scientific discovery. The same nodules are rich in rare earth metals such as lithium, cobalt, nickel, copper, and manganese—critical components in batteries, wind turbine, and solar panels—making them a prospect for deep-sea mining.
Because the CCZ is outside national jurisdiction, deep-sea mining in this region is regulated by the International Seabed Authority. Fifteen-year contracts for mining exploration (in total) have been granted to 19 contractors for PMN in the CCZ (17), Central Indian Ocean Basin (1), and Western Pacific Ocean (1).
Loke Marine Minerals holds two PMN-exploration contracts in the CCZ. They estimate their resources to include 10 million tons of nickel, 1.4 million tons of cobalt, 8 million tons of copper, and 210 million tons of manganese. Established in 2019, Loke has conducted three research cruises in the Pacific Ocean CCZ, generating more than 57,000 images of the seafloor and collecting more than 27,000 biological samples and observations.
Concerns about mining of PMN include significant environmental impacts on delicate and largely unexplored marine ecosystems. The disturbance of the seabed, potential release of toxic substances, and loss of biodiversity are key issues that need careful consideration. Balancing economic benefits with environmental stewardship and social responsibility will be crucial.

For Further Reading
OTC 35088 Direct Lithium Extraction from Geothermal Brines: The New Oil by H. Lebit, Alma Energy; B. Brunner, The University of Texas at El Paso; N. Kharitonova, Alma Energy; and E. Deemer, The University of Texas at El Paso.
Evidence of Dark Oxygen Production at the Abyssal Seafloor by A. Sweetman, GEOMAR Helmholtz Centre for Ocean Research (Kiel, Germany); A. Smith, Heriot-Watt University; D.S.W. de Jonge, The Scottish Association for Marine Science, et al.