Direct Lithium Extraction from Geothermal Brines: The New Oil

Abstract

Abstract The energy transition is an inevitable global development driven by geopolitical, environmental, economic and societal factors. It will fundamentally change how we access energy resources and how we will rebalance the growing demand in critical commodities. The global mobility sector consumes about 2/3 of the world crude oil production, which stands currently at or above 105 million barrels of oil per day (mmbopd). Even a minor reduction, for instance by increasing the electric vehicle fleet, would reduce greenhouse gas emissions but further stress our power grids along with an increasing demand in critical minerals, required by clean tech manufacturing. Industry strategies and technology developments have to address this conundrum. Renewable energy sources already significantly contributing to the domestic electricity grid (13% in US in 2021) but are dominated by intermittent resources like wind and solar energy, whereas dispatchable, clean energy resources are neglected. The potential of dispatchable geothermal energy is undisputed, though challenges in subsurface risk assessment, completion technologies, upfront investments and lengthy permitting processes impact the economic potential of this technology. Lithium is the key critical mineral in clean tech, particularly for batteries in the mobility sector due to its excellent energy density to weight ratio. Environmental impact of invasive lithium mineral mining or large evaporation ponds can be avoided by Direct Lithium Extraction from brines. It is a valuable solution particularly when deployed in proximity to mature hydrocarbon basins, attributed to a wealth in subsurface data, existing infrastructure, and qualified human resources. DLE technologies are facing some challenges in terms of freshwater usage, the application of chemical agents, excessive land usage and reliance on external energy supply. Finally, not every brine chemistry is suitable for the envisaged DLE technology. Direct lithium extraction based on electrodialysis employs ion-selective membranes in a clean, emission free process. The technology is robust and takes advantage of successful membrane applications at multiple desalination plants around the world. Along with battery-grade lithium the electrodialysis produces green hydrogen, outputs freshwater and sequesters CO2 as by-products. When combined with a geothermal power generation the technology uses onsite energy and the produced brine in a clean and environmentally friendly process. Lithium-rich reservoirs with a favorable geothermal signature have been reported from mature hydrocarbon basins across the United States and their direct lithium extraction offers attractive economics, given the growing lithium demand forecasted for the next decades. The operations are 100% green and self-sustainable when combined with novel low enthalpy geothermal power production technology. It opens a new running room to rejuvenate mature hydrocarbon basins into energy super basins.