Researchers at the Pacific Northwest National Laboratory (PNNL) are developing innovative methods to extract critical minerals from seawater, potentially securing a vast supply of materials for global energy needs. By utilizing three distinct processes, the team aims to recover magnesium, lithium, nickel, and rare-earth metals from ocean water and desalination brine. These technologies include a streamlined co-flow reactor for magnesium production, the use of desalination byproducts as leaching agents for terrestrial mining, and the harvesting of minerals from seaweed. While these methods show promise, the team is currently focused on scaling these technologies to achieve commercial economic feasibility.
The PNNL team’s primary innovation is a patented co-flow reactor that simplifies magnesium extraction. Unlike the traditional, multi-stage Dow process, this method flows seawater alongside a base to produce high-purity magnesium hydroxide. By integrating these reactors into existing coastal desalination plants, researchers believe they could produce significant quantities of magnesium hydroxide—potentially triple the current United States usage—while simultaneously processing water for freshwater production. This approach maximizes the utility of the massive volumes of seawater already being moved by desalination infrastructure, turning a logistical challenge into a resource-recovery opportunity.
Beyond magnesium, the researchers are addressing the environmental impact of concentrated brine left over from desalination. Using bipolar membrane electrodialysis, they can split this brine into acidic and alkaline streams. The resulting acid serves as a highly effective leaching agent for extracting nickel from ground-based minerals like olivine. Additionally, the team is investigating the use of seaweed, which naturally accumulates minerals at concentrations far higher than the surrounding water. By processing harvested seaweed, researchers hope to recover these dilute elements, while also exploring ways to convert the remaining biomass into fuel, fertilizer, or other chemical products.
Despite these advancements, significant hurdles remain before these processes can be deployed at scale. While the laboratory has successfully recovered various metals, the transition to a commercially viable ocean-mining operation requires further development. Furthermore, the researchers must address complex environmental considerations, including the long-term effects of chemical discharge, brine management, and potential ecosystem disruption caused by large-scale intake systems. The seaweed extraction project, in particular, remains in the early stages of research, requiring massive cultivation and harvesting efforts to become practical. PNNL continues to refine these interdisciplinary projects to improve efficiency and economic viability.