Magrathea, a California-based startup, has activated a pioneering electrolyzer capable of producing magnesium metal from seawater, promising significant climate benefits for industries that rely on this lightweight metal. Magnesium is crucial as a component in vehicles, aircraft, aluminum alloys, and defense and industrial sectors, but current global production generates considerable greenhouse-gas emissions. China´s dominance in the magnesium market, accounting for about 95% of the global supply as of 2024, has made it challenging for other producers to compete, especially as many rely on methods with high environmental costs.
Magrathea´s electrolyzer builds on established technology but introduces innovations to address efficiency and emissions. The process begins with magnesium chloride salt derived from seawater, salt lakes, or groundwater, which is then heated to about 700°C in the electrolyzer. By running the reactor at temperatures roughly 100°C above the minimum required to keep the salt molten, Magrathea adds flexibility—enabling the use of intermittent and potentially lower-cost renewable energy for various stages, such as drying magnesium salt ahead of time. This approach allows the company to maximize the use of renewable electricity, reducing both costs and emissions. The process also produces a magnesium oxide byproduct capable of capturing carbon dioxide from the atmosphere, further enhancing its environmental credentials.
A recent independent life cycle assessment concluded that, if scaled successfully, Magrathea´s method could achieve net-zero greenhouse-gas emissions. However, the path to market remains uncertain given China´s ability to offer lower-cost metal and established trade protections in the US. Production setbacks at the only other US magnesium maker in recent years highlight additional challenges. Magrathea is moving forward with plans to construct a demonstration plant in Utah, slated for late 2025 or early 2026, with a 1,000-ton annual capacity and operations expected in 2027. The company has already secured a material pre-purchase agreement with a major automaker, signaling early industry adoption as it eyes a larger commercial facility targeting 50,000 tons per year after the Utah site is operational.
