Lithium mining: New study reveals a hidden cost of renewable technology

It turns out lithium brine mining is less than "green".
Christopher McFadden

Researchers from the University of Massachusetts Amherst (UMass) and the University of Alaska (UAA) Anchorage have released a ground-breaking new analysis on the environmental impact of lithium brine mining. The first to fully account for the hydrological impact of lithium mining, the new study is an interesting insight into the all-to-often ignored "hidden cost" of renewable technologies that use lithium as a raw material.

The full study can be found in the journal Earth's Future.

The new study provides some very interesting insight into the processes behind extracting lithium, which is a key component in lithium-ion batteries. These batteries are essential for the switch from fossil fuels to renewable energy.

The age and source of the water in which lithium is found are two of the most crucial aspects of assessing if lithium is obtained ethically that are often not covered in various studies on the true environmental impact of certain renewable and sustainable technologies. Despite the fact that the team also notes that the impact of lithium mining alone is rather minimal, this first-of-its-kind study reveals that total water demand in the Salar de Atacama is outpacing its resupply.

For example, they found that less than 10 percent of fresh water is used for lithium mining, and changes in surface-water characteristics or basin water storage are unrelated to brine extraction.

Lithium is a peculiar element, according to David Boutt, a professor of geosciences at UMass Amherst and one of the paper's co-authors. Although it is the lightest metal, it doesn't like to be solid under normal conditions. Although lithium frequently occurs in layers of volcanic ash, it reacts with water quite quickly.

For this reason, lithium leaches into groundwater as rain or snowmelt passes through the ash layers. It travels downward until it settles in a flat basin, where it remains in solution as a salty mixture of water and lithium. This brine is so dense that it frequently falls beneath pockets of fresh surface water that float on top of the brine. These freshwater lagoons frequently turn into havens for iconic animals like flamingos and rare, vulnerable ecosystems.

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The investigation was conducted in the Salar de Atacama, an 850 square mile (2,201 km2) salt flat in arid Chile that has more than 40 percent of the world's known lithium resources.

The Salar de Atacama is the ancestral home of numerous Atacameo indigenous groups, with whom the UMass team collaborated, and is also home to a number of ecologically distinctive animal preserves. The usage of water in the Salar de Atacama bears the risk of disrupting both the ecological health of the region and the indigenous ways of life because the salt flats are so environmentally sensitive and depend on limited supplies of fresh water.

However, there hasn't been a thorough method of evaluating water use or the effects of lithium mining in the Salar de Atacama until today.

lithium brine mining no green
Piles of salt are ready for collection at the Uyuni Salt Flat in Bolivia. The crust sits a few centimeters above a pool of lithium-rich brine. Source: Dan Lundberg/Flickr

The hydrology of the region is very complicated

“To understand the environmental effect of lithium mining,” Brendan Moran says in a press release, a postdoctoral research associate in geosciences at UMass Amherst and the lead author of the paper. “We need to understand the hydrology in the region the lithium is found. That hydrology is much more complex than previous researchers have given it credit for.”

Moran and Boutt use the analogy of a bank account to highlight the complexity and prior misunderstanding of the hydrology of the Salar de Atacama. Imagine receiving a paycheck each month. When you balance your checkbook, you find that you are financially stable as long as your monthly expenses do not exceed your monthly income.

It turns out that the assumption made in earlier studies of the Salar de Atacama about the only factors affecting the water levels in the salt flats was the infrequent rainfall and seasonal runoff from the mountain ranges surrounding it.

While localized, recent rainfall is crucial; more than half of the freshwater supplying the wetlands and lagoons is at least 60 years old, according to research by Moran and his colleagues.

“Because these regions are so dry, and the groundwater so old,” says Moran, “the overall hydrological system responds very slowly to changes in climate, hydrology, and water usage.”

These findings were made using a variety of water tracers that can track the path that water takes on its way to the Salar de Atacama as well as the average age of water within different water bodies, including surface waters and sub-surface aquifers.

According to Moran, the total hydrological system reacts very slowly to changes in temperature, hydrology, and water demand since these locations are so dry and the groundwater is so ancient. The surface water and the delicate habitats they support can undergo significant and quick changes as a result of short-term climatic shifts, such as the recent large drought and extreme precipitation events.

Climate change could further strain the region's water budget because it is projected to bring about more severe droughts in the area.

In keeping with the accounting metaphor, the paycheck is probably getting smaller and won't arrive every month but rather over a period of at least 60 years. As a result, researchers must monitor water usage over a much longer period of time than they currently do and keep an eye out for significant events like droughts in the area.

Together with these geochemical tracers, other techniques are needed for comprehensive hydrological monitoring. The UMass and UAA teams used rain gauges, satellite measurements, and water usage statistics from the Chilean government to analyze changes in wetland extent over the previous 40 years. They also used satellite measurements to determine variations in precipitation over the same time period.

The repercussions of water overuse "may still be making their way through the system and need to be closely monitored,” explained Moran, “potential impacts could last decades into the future.” This is because groundwater takes so long to travel throughout the basin."

In the end, this extensive framework—funded by BMW Group and BASF—can be used elsewhere besides the Salar de Atacama. “It’s a modern approach to water management,” concluded Boutt.

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