LITHIUM’S DIRTY SECRET
Powering the green revolution
We’re in love with lithium for its light weight and green power potential. But, as RICHARD A LOVETT reports, lithium’s problem is that it’s not easy – or clean – to extract.
As the climate warms, sea levels rise and droughts, heatwaves and bushfires multiply, the need to usher in the green-energy future is increasingly urgent. But that doesn’t mean it can be done without significant challenges – not just in the economy (as it makes the changeover), but technologically and scientifically as well.
It’s a problem reminiscent of the 1970s environmental rallying cry TANSTAAFL (There ain’t no such thing as a free lunch), drawn from a 1966 novel by science fiction writer Robert A. Heinlein. All things come at a price, the idea goes, and while the price of excessive reliance on fossil fuels is increasingly evident, that doesn’t mean there aren’t going to be issues with weaning ourselves off them. One of these “issues” is lithium.
Most of us have never seen pure lithium, and never will. In this form, it is a soft silvery-white metal that so easily corrodes it has to be kept in mineral oil to protect it from air. But we all use it: it’s the magic ingredient in the lithium-ion batteries that power everything from our smartphones and watches to electric vehicles.
Prior generations of rechargeable batteries used lead and acid, nickel-cadmium mixes, and nickel mixed with other materials. Lithium, however, is a
A WORLDWIDE CLAMOUR FOR BETTER BATTERY POWER HAS CAUSED A “WHITE GOLD” RUSH ON LITHIUM. SHORTAGES LOOM, WRITES RICHARD A. LOVETT,
FUELLING A RACE TO FIND NEW SOURCES OF THIS RARE ELEMENT.
lot less toxic, holds its charge better when not in use, and is less susceptible to developing the “battery memory” problem in which ageing batteries fail to fully recharge. But its biggest advantage is that it is a lot lighter. Lithium is element number three on the periodic table: eight times lighter than nickel, 16 times lighter than cadmium, 30 times lighter than lead.
In other words, when it comes to batteries, it packs a lot more bang for the buck (or, more precisely, the gram). “For a given weight, it will have the maximum amount of power,” says Edward Goo, director of the materials science program at the University of Southern California’s Viterbi School of Engineering.
Michael Whittaker, director of the newly formed Lithium Resource Research and Innovation Center (which sports the musical-sounding acronym of LIRRIC) at America’s Lawrence Berkeley National Laboratory, adds that lithium is so light that it makes up only 1-2% of a lithium-ion battery’s total mass. If you’re going to haul it around in a wristwatch, laptop computer, electric vehicle, or even an airplane, he says, it really is vastly better. “For lightweight applications, lithium batteries will likely remain an integral part of the battery market for a long time to come,” he says.
There’s just one fly in the ointment. There are concerns about how we can get enough of it to power the alternative-energy future. Demand is expected to double in the next five years – and increase tenfold by 2030. And that has everyone scrambling to find new sources of it, lest lithium shortages grind the green economy to an unhappy halt.
One of the biggest drivers of that expanding demand is going to be electric vehicles. A Tesla Model S needs 64 kilograms of lithium – roughly 10,000 times the amount in the typical mobile phone. With current global production at 77,000 tonnes, according to the US Geological Survey (USGS; 2019 data), that means the world is only producing enough lithium to power 1.2 million new electric cars per year – at a time when total automobile production is more like 92 million. If the phrase “drop in the bucket” comes to mind, you might not be all that far off.
But that’s not the only way in which the greenenergy future will call for vast increases in lithium production, says Whittaker’s colleague Peter Fiske.
Climate change already appears to be fanning the flames of fires in large parts of the world, from California to Australia, and power companies are realising that they need to cut service in dry, windy conditions, lest sparks from downed powerlines produce catastrophic conflagrations. “All of us had the power to our houses shut off at least once this summer,” Fiske says of himself and his colleagues. “We are now imagining that shutting off the power grid is going to be a fact of life.”
To weather such shutdowns, people in fireprone areas are going to want something to tide them through, and batteries are an obvious answer. Already, Tesla is marketing Powerwalls that can do this, as well as store solar energy from sunny days and parcel it out when the clouds hang low. “This will further add to the demand for lithium,” Fiske says.
The green economy’s need for lithium highlights an important difference between it and traditional fossil fuels, which you can just pull from the ground and burn, says Jordy Lee, a policy analyst at the Payne Institute at the Colorado School of Mines. “Renewables are just so much more material intensive,” he said in a December 2020 podcast for Resources for the Future, a nonpartisan thinktank in Washington, DC. “That’s not something people know.”
Lee was talking specifically about rare earth elements – a group of 17 metals with exotic names like neodymium, dysprosium, terbium, indium and praseodymium – which are useful in everything from making magnets for wind-turbine generators and electric cars to hardening the glass in your smartphone screen. Not that these elements are truly rare. The problem, Lee says, is that they don’t tend to form concentrated ores from which they are easily separated out. “Where you might find large amounts of copper in a single area, or huge veins of gold, rare earths are embedded in other rocks and minerals. You could think of it as like a dusting of salt, as opposed to a big rock.” Important as rare earths are for the overall green-energy future, however, when it comes to batteries, they are a relatively small component. For batteries, the resource everyone is concerned about is lithium. But the problem is the same. “It’s very finely distributed,” says Whittaker. “You have to sift through quite a bit of material.”
By all rights, lithium should be the third most common element in the Universe. In general, that’s the way it goes. Hydrogen, the lightest, is far and away the most abundant, composing the bulk of stars, the galaxy, and the Universe as a whole. Helium, element number two, is second. And for the most part, heavier elements line up the same way, decreasing in abundance as you move from lighter to heavier. It’s not a perfect progression, but that’s the basic way it works.
Not so for lithium. It doesn’t even come close to making the top 10. Or the top 20. Rather it appears to be about 25th, only slightly ahead of such littleknown elements as tellurium (element number 52), and not that much more common than platinum (78) and mercury (80).
The reasons lie not on Earth, but in astrophysics. Or, as Fiske quips, inverting Shakespeare’s famous
line, “the fault is not in ourselves, but in our stars”. When the Universe formed, 14 billion years ago, the power of the Big Bang produced a lot of hydrogen, a substantial amount of helium and a bit of lithium, mostly in the first five minutes. “Lithium barely made the cut and was sort of made as a byproduct,” says Benjamin Kaiser, a graduate student at the University of North Carolina and first author of a January 2021 paper on the astrophysics of lithium in Science. Still, it did start out as the third most common element. Then bad things started to happen to it.
When stars form, they are powered by the fusion of lighter elements into heavier ones. That means that over time, the heavier ones should accumulate. But not lithium. Instead, Kaiser says, stars actually consume their primordial lithium as fuel. “It’s really easy to burn,” he says. “Even brown dwarfs [very cool, dim stars] can burn it.”
Another problem, says Paul Mason, an astrophysicist at New Mexico State University, is that the processes by which stars convert hydrogen and helium into heavier elements tend to leapfrog over lithium in favour of heavier elements, such as carbon, nitrogen and oxygen, partly because whatever lithium gets formed as a byproduct is either in unstable isotopes, or is quickly consumed to make something else. The same happens to elements number four (beryllium) and five (boron). “So lithium gets left out,” he says.
Luckily, not all of the early Universe’s lithium was burned up. And, Mason says, there are other ways in which it can be produced, including supernova explosions and the impact of cosmic rays (highvelocity protons) on helium atoms. “This is called cosmic-ray spallation,” he says. “Something like half of all lithium was formed in the Big Bang, and the other half from cosmic-ray spallation.”
Here on Earth, industrial production of lithium comes from two sources. One is traditional mining of rocks containing lithium ores, particularly a mineral called spodumene: a mix of lithium, aluminium, silicon and oxygen (LIALSI2O6) that can form crystals so big the US Geological Survey (USGS) has described them as “logs”. The biggest known have attained lengths of 13 metres and widths of 160 centimetres. “You can buy them on ebay,” (though not quite at that size) Lee told Cosmos.
“Spodumene contains [as much as] 3.7% lithium by mass, and is one of the highest-grade lithium ores known,” Whitaker says. “There are a number
LUCKILY, NOT ALL OF THE EARLY UNIVERSE’S LITHIUM BURNED UP. AND THERE ARE OTHER WAYS IN WHICH IT CAN BE PRODUCED, INCLUDING SUPERNOVA EXPLOSIONS AND THE IMPACT OF COSMIC RAYS ON HELIUM ATOMS.
of spodumene processing operations, mainly in Australia.” In fact, thanks to these, Australia has become the world’s largest producer of lithium, accounting for about 54% of the world’s production, according to USGS statistics.
But it doesn’t have the world’s largest reserves. Those, USGS reports, lie in Chile and Argentina, where lithium-rich water is pumped from beneath the surface of dry lakebeds called salars and allowed to evaporate in the harsh sunlight of the starkest deserts in the world. Those two countries, plus Bolivia, whose similar lithium brines are currently untapped, form what Lee calls the “lithium triangle” and contain at least 60% of the world’s known reserves as of 2019 (the latest year for which figures are available).
These reserves are large enough that we aren’t going to run out soon – though if demand continues to grow exponentially, they might become seriously stretched by the late 2030s. In fact, Lee argues, “we will never run out of any material because of scarcity. It’s always going to be economic, environmental and social concerns.”
But such issues could put a crimp in the lithium future.
Spodumene mining has the problem that you have to dig it out of the ground in big open-pit mines, truck it to a processing facility, crush it up, separate the spodumene crystals from several times as much matrix rock, and go through a complex process to extract it. It’s not only expensive and labour intensive, Lee says, “it is probably pretty carbon [energy] intensive”.
In fact, according to an online description by the mining division of Swiss consulting giant SGS, the ore must first be roasted at temperatures as high as 1050°C. This causes the spodumene crystals to expand by about 30%, making them more susceptible to the next step, which involves bathing them in high-concentration sulphuric acid – after which they are again heated, although this time only to 200°C.
It’s not the green-energy dream. Evaporation from underground brines, as is done in South America, avoids these problems. There are no harsh chemicals, there is no need to truck millions of tonnes of material to the mill, and rather than using fossil fuels or other high-intensity power sources to heat them to extreme temperatures, they are simply left in the sun to dry. But the process still raises concerns, the biggest of which is its effect on groundwater. “They don’t know what happens if you take out too much water,” Lee says. “What happens to the ecosystem? The water may not replenish.”
Maintaining the green-energy future means not just finding more lithium, but also finding more benign ways of producing it. And that, Whittaker says, is what the LIRRIC program is all about.
Currently, he and his colleagues see two new “unconventional” sources of low-cost, environmentally benign lithium. Top of the list is coproduction from geothermal energy, of which the US is currently by far the world leader, with a capacity of more than 3600 megawatts, according to Think Geoenergy. Indonesia, however, is rapidly catching up, with the Philippines, Turkey and New Zealand rounding out the top five. (Australia, a land largely devoid of active volcanoes and the easily tapped geothermal heat that comes with them, is 23rd in this field.)
For those countries with the resources, says Will Stringfellow, an environmental engineer at LIRRIC, geothermal power is definitely going to be part of the carbon-neutral future. And if it can be combined with lithium production, he says, “this is a win-win.”
Stringfellow’s personal focus, however, is on one of California’s leading geothermal energy sources, the Salton Sea Geothermal Field in the desert south of Palm Springs, which, he believes, could double up geothermal power and lithium production to become a “Lithium Valley”, as important to renewable energy as Northern California’s Silicon Valley is to computers.
Geothermal power production is a process in which fluids are circulated underground, where they pick up underground heat and bring it back to the surface to produce electrical power. As they circulate, they also pick up minerals, including lithium. And this, Stringfellow says, can be extracted – not by the waterwasting method of evaporation ponds, but directly, via ion-exchange processes, in which synthetic resins are used to extract dissolved materials. It’s a method widely used for everything from wastewater treatment to food processing, and has already been shown to be technologically feasible for extracting lithium, Stringfellow says, though, he admits, “making it economically successful is more difficult.” The main obstacle, he says, is dealing with other minerals, such as silica, magnesium, calcium, manganese and zinc, that can interfere with the process.
Still, he says, “I think we are on the verge of it. The economics are right, the demand is rising, and the political stars are aligning to help us push forward.”
And there’s potentially a lot of lithium. According to Whittaker, the water powering the Salton Sea geothermal plants contains about 180 parts per million of lithium. And there’s a lot of it: his team has estimated that it has the potential to supply somewhere between 8% and 40% of current global demand. That’s a wide range, but it’s enough to attract two competing firms – Controlled Thermal Resources, in Brisbane, Australia, and US billionaire tycoon and philanthropist Warren Buffett’s Berkshire Hathaway Energy – to work on the project.
With all that lithium available, plus hundreds of megawatts of geothermal power, Stringfellow says the Salton Sea is a perfect area in which to build an entire lithium industry in a single location – the core of the
FOR THOSE COUNTRIES WITH THE RESOURCES, GEOTHERMAL POWER IS DEFINITELY GOING TO BE PART OF THE CARBON-NEUTRAL FUTURE. AND IF IT CAN BE COMBINED WITH LITHIUM PRODUCTION, IT’S A WIN-WIN.
Lithium Valley concept, in which lithium is extracted and converted to batteries, with the manufacturing facilities powered by the area’s abundant geothermal energy. It quickly becomes clear why he and Whittaker are so excited about the idea.
That’s not the only possible alternative source, however. Seawater also contains lithium, and while there’s not a lot per litre – somewhere around 0.1 to 0.2 parts per million – it adds up. In a 2018 paper in the journal Joule, Sixie Yang, et al, from Nanjing University, calculated that the oceans contain 16,000 times more lithium than all known terrestrial reserves.
Extracting it is the issue, because it takes a lot of seawater to get a tonne of lithium. But, Fiske notes, we are already doing that on a fairly large scale at desalination plants. Globally, 38 billion litres per day of drinking water are made from salt water. “The concentrated brine just gets discharged to the ocean,” Fiske says. “If you can extract the lithium from it,” he adds with a touch of understatement, “that’s good.”
Those 38 billion litres of seawater contain four to eight tonnes of lithium. Multiply that by 365 days in a year, and you get about 20% to 40% of the world’s current lithium usage. And while most of the water being desalinated comes from the ocean, some comes from other sources that, Whittaker says, can have many, many times as much lithium. Not enough to solve the world’s lithium needs in and of itself, but still, an enormous potential resource, currently being summarily dumped.
Other vast new sources of lithium may also exist, including lithium dissolved out of ancient volcanic rocks and washed into desert salt flats and alkaline lakes. But wherever they exist, the clean, greenenergy future deserves a clean, equally green way of obtaining the materials it so vitally needs.
It’s also going to need the same type of international cooperation that went into the Paris Agreement and other multinational efforts to stave off the worst effects of global warming. Yes, these new methodologies, especially extraction from seawater, could help ensure the energy security of any country with access to the ocean. But to save the planet, it’s got to be a cooperative effort, not a competition.
“We’re going to need as much lithium as we can get,” Whittaker says.
RICHARD A. LOVETT is a science and science fiction writer based in Portland, US. His story about Hayabusa2 and OSIRIS-REX appeared in Issue 88.