lithium extraction from geothermal energy plants
German scientists have suggested lithium for use in batteries could be extracted from geothermal energy plants to reduce reliance on imports
Pumping up thermal water, separating lithium, and using it to produce batteries for electric mobility – the idea of lithium as an environmentally compatible and regionally available by-product of geothermal energy plants appears highly promising.
However, it has not been clear so far whether domestic lithium extraction is really worthwhile.
A team of researchers from Karlsruhe Institute of Technology (KIT) has now summarised the state of the art, analysed raw materials markets, and assessed technologies.
According to them, it might be possible in theory to extract thousands of tons of lithium every year in Germany, but crucial aspects still need to be clarified.
See also: Lithium-ion battery materials degradation better understood
lithium shortfall
For the energy transition, Europe needs a lot of batteries and sufficient lithium to produce them.
The European Union (EU) accordingly classifies lithium as a critical resource, but there is a danger of a lithium shortfall.
Valentin Goldberg, from KIT’s Institute of Applied Geosciences (AGW), said: “We are entirely dependent on imports. Worldwide, 80% of lithium resources come from Chile and Australia.
“At the same time, we deliberately accept major environmental expenses due to the conventional extraction of lithium in these countries, including negative impacts on groundwater.”
Lithium extraction in geothermal power plants, by contrast, is planned to be based on existing infrastructure in Europe, where large volumes of thermal water with a sometimes-high lithium concentration are being extracted.
Following energy production, lithium will be separated, and the remaining water will be fed back into the underground, as usual during operation.
Goldberg added: “In principle, we are very positive about this technology.
“Hardly any space would be needed, environmental and transportation costs would be low.”
To realistically determine the potential future share of domestic lithium, Goldberg and his colleagues from AGW have collected the available knowledge, analysed it, and for the first time calculated the potential for Germany.
planned battery production
The potential lithium extraction volume does not only depend on the water’s lithium concentration, but also on the location-dependent flow rate and reservoir dimension.
For their estimations, the researchers analysed potential locations in Germany, studied markets of raw materials, and assessed various technologies in terms of efficiency, applicability, and integration in geothermal energy production.
AGW’s Dr Fabian Nitschke, who was also involved in the studies, said: “On this basis, we have obtained an optimistic annual production estimate of about 2,600 to 4,700 tons lithium carbonate equivalent, provided that all relevant geothermal energy plants are equipped with the necessary systems.
“With this, we could cover about 2% to 13% of the annual quantity needed for planned battery production in Germany.”
Construction of additional geothermal power plants might increase the extraction volumes.
However, it will take at least five years for a newly planned power plant to start operation.
In view of the predicted global lithium shortfall and planned battery production, the situation in Germany will deteriorate soon.
Nitschke added: “For this reason, lithium from geothermal power plants will nothing but complement imported resources in the medium term.”
energy consumption
Prognoses still are subject to many uncertainties: the dimensions and the origins of lithium resources in geothermal systems as well as the response of the reservoirs to continuous extraction are being studied at the moment.
Moreover, extraction technologies are far from mature – essential development processes and long-term tests remain to be carried out.
Dr Tobias Kluge is another AGW author of the study. He stated: “But direct comparison already reveals specific advantages and drawbacks that are of particular relevance to economically efficient lithium extraction.
“The need for additional resources, damage caused by deposits in boreholes and extraction units, and energy consumption directly affect economic efficiency.”
But it is not further technology development or suitable locations that will decide on whether lithium will be extracted at German geothermal power plants; public support and acceptance will be required.
Goldberg stated: “Our publications in the journal Grundwasser (groundwater) do not only address experts; we rather want to give decisionmakers in politics and industry, as well as the interested public, the chance to inform themselves directly and independently about opportunities and challenges.”
Now, the findings can be used as a basis for future research and development in this area.
Image: A geothermal power plant at Unterföhring near München. © Stephan Kelle 2016, https://www.geovol.de/
