Are EVs using too much water?
Posted: July 11, 2024
Many of us hope that electric vehicles (EVs) will help us drastically reduce our carbon emissions. But, EVs come with their own problems, just like any technology. For instance, an electric vehicle can use nearly twice as much water to manufacture and operate as a car with an internal combustion engine.
One reason EVs consume so much water is that their batteries are made of lithium and other minerals that often require huge quantities of water to mine and extract. Global demand for lithium is expected to grow by a factor of at least 18-20 between 2020 and 2050.
In part because of this lithium mining, some regions of Chile are running out of water. Some mines have been forced to stop operations and some communities have resorted to pumping desalinated water hundreds of miles as their wells have dried up. Both vegetation and flamingo populations have been decreasing near areas of lithium mining in the Atacama region, indicating that water is becoming more scarce.
Water for lithium mining
Everyone seems to agree that mining lithium uses enormous amounts of water—though just how much it uses is hard to tell, in part because it’s not clear how much of the water used for mining can be recycled to use again for drinking, agriculture and other applications.
Most (though not all) lithium comes from eight sites—four in the “lithium triangle” of Bolivia, Chile and Argentina, three in China, and one small site in the U.S. At these sites, lithium is found dissolved in underground reservoirs of brine. Miners pump this brine to the surface into shallow pools, where the water evaporates over the course of one or two years. The evaporated brine leaves behind lithium chloride and other mineral salts. Miners then extract the lithium chloride and refine it into a final product, usually lithium carbonate.
For every metric ton of lithium carbonate produced by this process, about 25,000 to 200,000 gallons of water evaporates from the brine in the evaporating pools.
When the hundreds of thousands of gallons of brine get pumped from these underground reservoirs, fresh water from nearby reservoirs seeps back in to take its place. So, water that used to be fresh and potable has now turned to unpotable brine. Just how much fresh water gets contaminated by this process is poorly understood.
For every metric ton of lithium carbonate extracted, 115 metric tons of other salt mixtures end up accumulating as waste. Over the course of a year, that’s equivalent to about 4.5 square miles (11.5 km2) of waste piled three feet (one meter) high. These salts may leach into the ground, further contaminating freshwater reservoirs in the vicinity.
In addition to all this water involved in extracting lithium chloride, refining it uses even more fresh water. Refineries pump fresh water directly to use for chemical processes, mineral washing, and steam.
Alternative lithium extraction
New direct lithium extraction (DLE) techniques use chemical, thermal, electrochemical and filtering processes instead of evaporation to extract lithium from brine. Once the lithium gets extracted, the brine could then—in theory—be returned underground without upsetting local fresh water supplies too much.
Some lithium deposits in Australia and China are in the form of hard-rock ores that don’t require the water-intensive evaporative extraction used at South American sites. These Australian deposits accounted for over 40% of global lithium extraction in 2022. However, even hard-rock mines still pose contamination risks to waterways and groundwater.
Another way to reduce EV water use is to simply reduce the amount of lithium EV batteries require. Microsoft and the Pacific Northwest National Laboratory recently used AI to discover new battery materials that use less lithium.
Better than fossil fuels
For all the water that goes into mining lithium and other minerals for EVs, the Oxford data scientist Hannah Ritchie argues that it’s dwarfed by the water that goes into petroleum extraction.
While it’s true that EVs can use twice as much water as gas-combustion cars, most of that water comes from extracting the fossil fuels that feed the power grids that charge their batteries. An EV that charges solely on electricity generated by renewables consumes just one third the water of a gas-powered car. So, while EVs use significantly more water than gas-powered cars right now, they have the potential to use significantly less water—as long as we continue to transition the grid to renewables.
Water: A local problem
Even so, increased demand for lithium and other minerals may still compromise water availability at locations near mining sites. That’s because over half of lithium extraction takes place in locales that are already under high water stress, such as the lithium-rich Atacama desert and the American Southwest. Lithium extraction also tends to have a disproportionate effect on socially marginalized communities as well. In the U.S. 79% of lithium reserves are within 35 miles of Indigenous tribal land.
To ensure the EV economy preserves the water we all need, we must prioritize both the transition to a renewable power grid and work to safeguard water supplies for the communities living near lithium extraction sites.
