Metal From Seawater

A startup aims to restore American magnesium production.

by Lee Harris

October 6, 2023

5:30 AM

Courtesy Science History Institute Archives

1942 and 1943 advertisements for Dow Magnesium featured a cube of seawater and a winged ingot of magnesium flanked by fighter planes.

An Oakland, California–based startup has a business plan that sounds like modern alchemy: turning seawater into metal, and using it to build cars, airplanes, satellites, and drones.

Magrathea Metals, named after a planet in the Douglas Adams sci-fi epic The Hitchhiker’s Guide to the Galaxy, is developing a more cost-effective way to reduce saltwater to cooked-down brines, and electrolyze the leftover salts to produce magnesium metal.

CEO Alex Grant hopes the product can be scaled to create lightweight, carbon-neutral alternatives to the dominant structural metals, aluminum and steel. The company has already signed multiple government contracts, Grant said, and has launched a project with an undisclosed major automaker.

Metal from seawater may sound fantastical, but the U.S. was already making it a century ago. Dow Chemical began producing magnesium for aircraft, car parts, and bombs in the 1920s. In the 1940s, Dow refined the process Magrathea is now hoping to resurrect, gleaning magnesium from the waters of the Gulf of Mexico.

More from Lee Harris

Yet today, there is only one primary producer of magnesium in all of North America, Europe, and Australia: Utah’s U.S. Magnesium, which has the unusual honor of having been declared a Superfund site while still in operation. U.S. Magnesium declared force majeure (an act of God) during the pandemic and has reportedly struggled to restore its facilities to full operating capacity.

As with so many other natural resources and critical components, China has gained a dominant position in the global supply of magnesium. Magrathea is proposing to restore America’s status as a major primary producer—this time, using renewable energy.

The company stands to benefit from the Inflation Reduction Act and its production tax credit for rare minerals. The question, as with direct lithium extraction using geothermal energy, is whether it can scale cost-effectively. The team has worked with retired engineers of Dow Magnesium and aluminum firm Norsk Hydro, who have shared best practices on materials handling. “Ten or 20 years from now, their knowledge is going to be lost. But we’ve been able to capture a lot, while they can still give it,” Grant said.

Part of a larger surge in manufacturing investment, Magrathea’s bid will test whether a materials science startup can compete with global metal-producing juggernauts, which have billions of dollars of steel in the ground.

AMERICAN MAGNESIUM PRODUCTION WAS BORN out of wartime disruptions to supply chains.

When Herbert Dow arrived in Midland, Michigan, in the 1890s, the area was environmentally blighted. Intensive lumbering had razed ancient forests, and with little left to chop, the logging industry was receding.

Dow saw an opportunity to draw on a far older resource: the briny remains of the region’s prehistoric seas, which run in deep aquifers across central Michigan. He launched a chemical business extracting bromine, magnesium, and other elements from that bitter water.

In 1914, a blockade by the Allied powers in World War I cut off imports from Germany, then the world’s primary magnesium producer. The restrictions highlighted American reliance on Germany for other vital goods like aspirin, dyes, and chemicals, and gave Dow an opening to expand magnesium production.

After an interwar lull, World War II intensified domestic demand for magnesium. Both aircraft bombers and the bombs they carried used magnesium, which flares brightly when it burns. Dow developed a process for extracting magnesium from the ocean, and in 1941 opened a new plant in Freeport, Texas, selecting the site for the cheap availability of natural gas, salt, sulphur, and oysters in Galveston Bay. Oyster shells were used to produce calcium oxide.

“There is an epic quality involved in the peopling of a flat, narrow tongue of waste land with strange shapes of structures and having them combine to take a ladle of gleaming metal out of a curling, white-capped ocean wave,” Dow wrote in a later report to Congress.

Courtesy Science History Institute Archives

View of the seawater intake apparatus at the Dow Chemical Company plant in Freeport, Texas

Magnesium demand fell off after WWII, with the Korean War briefly reigniting the market. Dow plowed magnesium instead into consumer goods, like sewing machines and baby strollers.

In the 1970s, UCLA industrial policy professor Marvin Lieberman wrote, Dow “shifted from its ‘limit-pricing’ strategy, designed to maintain Dow’s position as the dominant magnesium producer, to a ‘skim pricing’ type of strategy intended to maximize more immediate returns.” It raised the price of magnesium, sold off its magnesium research library, and moved magnesium research staff to other units.

U.S. Magnesium, which draws on the Great Salt Lake, began operating in 1972, and it was not until the 1990s that U.S. dominance as a global primary producer of magnesium began to slip. Tariff reductions led to increases in magnesium imports from China and Eastern Europe, and the U.S. became an importer. In 1998, when Hurricane Frances flooded the Freeport plant, Dow seized the opportunity to declare force majeure and exit the business.

New fuel economy standards, meanwhile, pushed carmakers to trim the weight of vehicles. Many swapped steel for lighter materials, like aluminum alloys that included some magnesium.

Global production of magnesium more than tripled between 1995 and 2023, but the U.S. share sank. Since there has been just one U.S. producer since 2001, the U.S. Geological Survey (USGS) has withheld national aggregate magnesium production statistics, arguing that it would be disclosing proprietary company data.

In 1994, China produced less than 5 percent of global magnesium; by 2014, it accounted for 87 percent of the global market, according to USGS figures. In 2021, shortages in Chinese magnesium prompted European carmakers and business associations to warn of “imminent risk of Europe-wide production shutdowns” because of dwindling magnesium supplies.

Also in 2021, U.S. Magnesium shut down due to equipment problems. Since then, the company appears to have restarted production. Multiple representatives could not be reached for comment.

Chemists have pointed out an annoying trade-off of “lightweighting”: While lighter vehicles produce fewer emissions on the road, making those lighter materials typically requires more energy up front, compared to the material being replaced.

China uses the Pidgeon process, a labor-intensive way of extracting magnesium through smelting, which emits carbon dioxide, and has typically relied heavily on coal. Although electrolysis is also energy-intensive, it relies on electricity, and could potentially be fired by renewables.

TWO ANGLOSPHERE MINING COLONY EXPATS have now teamed up on Magrathea. Before launching the company, Grant, originally from Canada, founded Lilac Solutions, a company developing similar technology for lithium extraction. He is working with Jacob Brown, an Australian who built a battery cathode pilot as an engineer at Tesla.

Their idea is to use wind, solar, and geothermal energy to power electrochemical magnesium production. The basic process for producing electrochemical magnesium requires seawater or other sources of salt, such as the brines left over in table salt or potash fertilizer production.

The brines are purified and evaporated down to magnesium salt, which is further processed to remove all water. (This dehydration technology is a key process Magrathea will be trying to refine.) The salt is then electrolyzed—separated with an electrical current—to produce magnesium metal, which can be cast into ingots or directly into machine components.

“The focus right now is displacing super carbon-intense Chinese mag from Western markets,” Grant said. Magrathea is focusing first on winning the existing magnesium market, as U.S. automakers and aluminum firms look to onshore and decarbonize their supply chains. Further out, the company aims to scale magnesium die casting to replace heavier “structural metals” like steel and aluminum, used in vehicles.

Alex Grant

Magrathea commissions its pilot-scale magnesium foundry, pouring a commercial-scale eight-kilogram ingot of magnesium.

The global steel industry is about a thousand orders of magnitude larger than magnesium. Given the staggering quantity of fixed capital in steel, Magrathea’s pitch to lift market share from steel remains far-fetched.

Grant points to Ford’s switch in the early 2000s to using more aluminum in their trucks, including the iconic F-150, which was seen at the time as unlikely to succeed.

Electric batteries have blown up the weight of vehicles, and automakers now acknowledge the urgent need to slim down. Ned Curic, chief technology officer at Stellantis, which makes cars including the Jeep, Dodge, and Chrysler brands, said in a recent interview with Automotive News Europe that the single biggest engineering challenge he faces is vehicle weight.

Several sustainable investment funds, including VoLo Earth, have taken an interest in Magrathea’s approach to securing metals without mining. Magrathea is also backed by Exor Ventures, the investment arm of Italy’s Agnelli family, which owns 14 percent of Stellantis and 24 percent of Ferrari. Grant touts this as a sign of the automotive industry’s “strategic interest” in magnesium.

Another investor is Kunal Sinha, global head of recycling at commodity trader Glencore.

So far, Magrathea has made just “a couple kilos” of magnesium, Grant said. The firm is building a pilot in Oakland with the capacity to make two tons of metal per year. The goal, he said, is to demonstrate a process to make anhydrous magnesium chloride at low cost.

Asked whether the company will aim to license its technology or continue operating it directly, Grant said the plan is “roughly” build-own-operate, “but there is a lot of nuance.” For example, he said, Magrathea wants to sell equity in assets, and partners might operate “chunks” of the operation.

But Grant underscored the importance of owning the technology at least until it reaches commercial scale.

“We will build smelters, and we will sell metal,” he said. “At every stage of scale-up, you run into technical challenges that you solve, and we want to be the people solving those technical challenges.”

Lee Harris is a staff writer at The American Prospect. In 2020, she co-founded New York Focus, an investigative news site on New York politics. Prior to that, she was editor of the independent newspaper at the University of Chicago.

October 6, 2023

5:30 AM

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