California desert could hold key to powering all U.S. EVs
Lithium from Salton Sea Basin mined more safely
The Salton Sea Basin feels almost alien. It lies where two enormous chunks of the Earth's crust, the North American Plate and the Pacific Plate, are very slowly pushing past one another creating an enormous low spot in the land. It's a big, flat gray desert ringed with high mountains that look pale in the distance. It's hot and, deep underground, it is literally boiling.
The Salton Sea, which lies roughly in the middle of the massive geologic low point, isn't really a sea, at all. The largest inland lake in California, it's 51 miles long from north to south and 17 miles wide, but gradually shrinking as less and less water flows into it. At one time, it was a thriving entertainment and recreation spot, business that has also largely dried up. It's left behind abandoned buildings and shallow, gray beaches. The highways that ring the lake are traversed now mostly by passing trucks.
Over the past few years, companies have been coming here to extract a valuable metal, lithium, that the car industry needs as it shifts to making electric cars. Lithium is the lightest naturally occurring metal element on Earth,and, for that reason among others, it's important for electric car batteries, which must store a lot of electricity in a package that weighs as little as possible.
What's more, with the Salton Sea Basin's unique geography, engineers and technicians can get the lithium with minimal environmental destruction, according to companies that are working there. In other places, lithium is taken from the earth using hard rock mining that leaves huge, ugly scars in the land. Here, it exists naturally in a liquid form, so extraction doesn't require mining or blasting.
Over thousands of years, floodwaters from the Colorado
River, carrying minerals pulled away from the Rocky Mountains, the Ruby Canyon, Glen Canyon, the Grand Canyon and more, have washed into these lowlands. Time and again the water has come and evaporated, leaving behind metals that have ended up deep in the ground.
Lithium is abundant in the Salton Sea Basin. In fact, people working to extract it say there could be enough to make batteries for all the electric cars expected to be built in this country for many years, freeing the United States from reliance on foreign lithium suppliers. That's been a priority for the Biden administration.
The Earth's crust is thin here, and there's water deep underground close to the seething hot liquid rock inside the Earth, called magma. Trapped in that naturally occurring oven, that water has become a super-heated mineral stew.
Geothermal energy companies have been here for decades drilling down into the nearly 700 degree water, allowing it to instantly boil up out of the ground. Steam from the hot brine — so-called because of its high mineral content — spins turbines, generating electricity. It's then pumped back down into the Earth where it gets heated back up to start over again. This sort of energy is considered clean and renewable since it relies onheat occurring naturally in the Earth.
“It's one of the largest geothermal energy fields in the world,” said Derek Benson, chief operating officer of EnergySource Minerals.
EnergySource Minerals wasspun off in 2018 from EnergySource, a geothermal power company that's been generating electricity from hot Salton Sea brine for a decade. EnergySource Minerals is now working to get lithium from the brine it's been using for energy.
How much lithium is here, exactly, and how much might be extracted, are questions that a research team from Lawrence Berkeley National Laboratories are working to figure out.
Roughly a quarter of the water taken from deep underground here is dissolved rocks, a vastly higher mineral concentration than you you'd find in ordinary seawater, according to Patrick Dobson, a Berkeley Labs geologist leading the research. Lithium makes up roughly 200 parts per million, he said, which compares to about 10 parts per million in some other hot geothermal fields.
“That's why this is of interest,” he said. “It's not just any geothermal brine. There's certain places where there's an enrichment in lithium in the brine and the Salton Sea is the place in the US where we're really focusing our attention on.”
People who've worked with this brine have long known about its contents, but there's no use for loads of undifferentiated minerals and selectively extracting them wasn't economical. But that was before electric cars became a big deal, and the price of lithium started to rocket. So companies have invested in new technologies to pull lithium from the brine.
“We use what we call lithium selective adsorption,” said Benson. “And so we pass the lithium bearing brine across one of our proprietary adsorbers. It has a chemistry that has an affinity for lithium and really only the lithium.”
One of the challenges is how efficiently these technologies can draw lithium out of the brine, said Berkeley Labs' Dobson. While there's a lot of lithium in the brine, these extraction techniques probably won't be able to take out 100% from every drop.
Also, as the lithium is taken out of the brine and the brine is then pumped back deep underground, will lithium levels be notably depleted or will the the levels be replenished as more lithium is leeched out of the rocks?
“We know from measurements of rocks that are still in the reservoir that not all the lithium is present in the brine,” he said. “There's still lithium present in the rocks.”
Collecting lithium now looks like a bigger moneymaker for companies like EnergySource than their original business of just generating electricity from the steamy soup. In fact, other companies are getting into the geothermal energy business largely so they can get lithium. In their case, electricity is just a bonus.