“Domestic sources of lithium are of great importance”

The energy deep beneath our feet is set to drive the heating revolution. Deep geothermal energy is the often used magical buzzword. But the hot water also contains another raw material without which the energy transition could quickly grind to a halt; lithium. This shiny, silvery metal has long since become the oil of our time. Valentin Goldberg from the Department of Geothermal Energy and Reservoir Engineering at the Karlsruhe Institute of Technology (KIT) has been investigating the potential of deep geothermal energy for the production of lithium. In this interview, he explains how it could be brought to the surface and why it would make sense.

What is the difference between deep geothermal energy and the kind we use to heat our homes?

It goes much further underground, typically three to five kilometers here in the region. This is the hydrothermal form of deep geothermal energy, because it involves drilling into water-bearing formations underground. The naturally circulating thermal water is tapped through the deep wells and pumped to the surface. There it transfers its heat to a heat exchanger. This heat is then either used directly or converted into electricity. The cooled water is then returned to the same formation underground. It is thus kept in a closed loop. Deep geothermal projects are typically centralized solutions implemented and operated by utilities or large industries.

And is lithium dissolved in recoverable concentrations in all German thermal springs?

No. Relevant lithium concentrations can only be found in certain geological formations. The Upper Rhine Graben and the North German Basin stand out.

And how is lithium extracted?

Just as lime is dissolved in our tap water, lithium is also present in dissolved form in the thermal water from the depths. The idea is to extract it selectively. The key word here is direct lithium extraction, or DLE for short. Several methods are currently being investigated. One is inorganic sorbents. These are, for example, ionic sieves that only incorporate lithium into their mineral structure. These are installed in the thermal water flow and filter out the lithium. Lithium extraction from geothermal water has been studied for over 50 years. However, such extraction systems are complex chemical plants that must be built in addition to the geothermal power plant. It's not like screwing in a little filter. Until now, the final technical maturity on an industrial scale has always failed because the price of lithium was too low. And that's different now, because the expansion of e-mobility in recent years has caused the price of lithium to rise sharply, making unconventional deposits more interesting.

How would domestic lithium affect our industry?

Based on our findings, the impact could be significant. You just have to remember that lithium is at the heart of today's advanced battery technology. It started with mobile devices such as laptops, tablets, digital cameras and cell phones. The automotive industry is now tied to batteries. And electricity storage for the energy transition is on the rise. This is the demand side.

And the supply side?

Well, three-quarters of the world's lithium comes from two countries: Chile and Australia. This means that we have a relatively undiversified market with only a few producing countries. At the same time, almost all lithium is processed in China. This makes our battery market very dependent. In terms of security of supply, domestic sources of lithium are very important.

What demand could be met by domestic production?

We have done the math. If all existing deep geothermal plants in Germany were immediately equipped with a lithium extraction plant, between two and 13 percent of the lithium required for battery production in Germany could be extracted. With every geothermal power plant in the relevant regions, it could be more.

Now, demand is one side of the coin. But what about the cost side?

Unfortunately, there are no commercial plants on an industrial scale from which we can directly derive the costs. But the drilling required for lithium extraction is comparable to that in the oil and gas industry, with costs in the tens of millions. Then there is the investment in the power plant and the extraction plant. All in all, various studies suggest a price of $4,000 to $5,000 per ton of lithium carbonate.  This is the form of lithium that is extracted at the end of the mining process and then processed into battery precursors.

And how do these costs compare to conventional lithium mining?

As mentioned above, there are two dominant lithium producers, and they mine in different ways. In Chile, lithium is extracted from salt lakes. The cost of extracted lithium carbonate is between $2,500 and $3,000 per ton. In Australia, lithium is extracted from an ore body using traditional open pit mining methods. The cost is about $5,000 per ton of lithium carbonate, which is about the same as deep geothermal.