General Motors is investing millions of dollars in a pioneering project to extract lithium—a critical metal in electric-vehicle batteries—from superheated waters deep under California, throwing its weight behind a drive to produce lithium sustainably while reducing U.S. reliance on foreign supplies.

The automaker said on July 2 it had agreed to a strategic investment and commercial collaboration with Controlled Thermal Resources (CTR), an Australian firm working to extract lithium from naturally heated geothermal waters under the Salton Sea, a lake in Southern California.

GM, which aims to be at the forefront of the electric-vehicle revolution, said a “significant amount” of its future battery-grade lithium could come from CTR’s Hell’s Kitchen project.

GM is the first company to secure rights to lithium from the Salton Sea area, where several companies have been striving for years to produce the metal, and its investment signals a crucial vote of confidence in the viability of lithium extraction there.

The California Energy Commission estimates the area could produce 600,000 tons of lithium carbonate annually, worth $7.2 billion. That would comfortably meet current global demand for the metal, used in batteries for cell phones and laptops, as well as for cars.

GM said it was making a “multimillion-dollar investment” in CTR’s project, but neither company would disclose the exact amount. The agreement gives GM first rights over lithium produced from the first stage of the Hell’s Kitchen project and includes an option to extend the agreement.

CTR’s CEO Rod Colwell told Fortune in June that the company plans to open a 20,000-tonne-per-year lithium hydroxide facility at the Salton Sea in the first quarter of 2024.

Tim Grewe, GM’s director of electrification strategy, said the automaker’s investment in the project could be just the start.

“If this turns out to be everything we think it can be, the investment is going to accelerate,” Grewe told Fortune.

“It’s a strategic alliance where we are going to make the investment, but we are also going to do our best to accelerate the technology. We come with innovation, along with investment, to try to make this happen,” he said.

GM, which aspires to phase out new gas- and diesel-powered light vehicles by 2035, said in June it would invest $35 billion in electric and self-driving vehicles through 2025. GM plans to build two new U.S. battery manufacturing plants by mid-decade, in addition to plants being built in Tennessee and Ohio.

The rush to produce lithium, also known as “white gold,” from under the Salton Sea has raised hopes locally that the area could develop into an integrated battery manufacturing hub.

Grewe refused to be drawn out on whether GM could site a future battery plant in California, but he said the Hell’s Kitchen project could supply enough lithium for a battery plant and potentially more than one.

He also said he believed the California lithium would be cheaper than imported metal.

CTR’s Colwell said GM had shown “great initiative and a real forward-thinking strategy by securing and localizing a lithium supply chain while also considering the most effective methods to minimize environmental impacts.”

CTR plans to harvest lithium as a by-product of geothermal power generation, which uses very hot water or steam drawn from deep underground to drive turbines and generate electricity.

The geothermal fluids, called brines, can reach temperatures as high as 572°F (300°C) underground, dissolving lithium and other metals from rocks. As well as generating power, Controlled Thermal Resources aims to extract lithium from the fluid before reinjecting it into the ground.

The company says the technique, called direct lithium extraction, produces negligible carbon dioxide emissions and eliminates the need for traditional carbon-intensive open-pit mining or evaporation ponds, which use vast quantities of water.

CTR says Hell’s Kitchen could eventually produce 300,000 tonnes of lithium carbonate a year as well as enough electricity to power over a million homes. The project could also yield rare earths and other U.S.-designated “critical minerals” in commercial quantities, it says.

Most of the world’s lithium today is either mined in Australia or produced in South America, where underground brine is pumped into ponds and left for months to evaporate in the sun, leaving behind lithium.

Much of that lithium is sent to be processed in China, which dominates the battery component supply chain. Research firm Rystad Energy said last week that China controls 74% of global manufacturing capacity of cathode, a critical battery component, with its share set to grow to nearly 84% in 2025.

For now, the only lithium production in the United States is from a brine operation in Nevada. Plans for new open-pit lithium mines in Nevada have run into opposition from environmentalists.

The U.S. Department of Energy last month announced an action plan to scale up the U.S. domestic manufacturing supply chain for advanced battery materials following a review of America’s supply chains ordered by President Joe Biden.

Several other companies are working to extract lithium from geothermal brine under the Salton Sea, including California-based EnergySource Minerals and BHE Renewables, a subsidiary of Warren Buffett’s Berkshire Hathaway, which owns 10 geothermal power plants in the Salton Sea area.