Geothermal Energy Could Supply Green Lithium

Geothermal Energy Could Supply Green Lithium


Lithium is a key element that will enable many of the solutions that we are currently developing to make our society more environmentally friendly. Among other uses, it is powers the batteries that are used in electric vehicles and stores excess renewable energy. It also supplies the power to many of the IoT sensors supply the data to make our manufacturing and buildings more efficient. The main problem with lithium is in short supply and that its extraction can be environmentally damaging.

It generally takes a lot of water to extract the lithium – it is estimated that around 500,000 gallons of water are needed per tonne of lithium extracted. The “Lithium Triangle” in South America contains around half of the world’s lithium reserves. The area, which covers parts of Argentina, Bolivia and Chile, is also one of the driest on earth. Much of the available water in the region is diverted away from local people and businesses to be used in the extraction of lithium. The evaporation method of extracting lithium also leaves toxic chemicals, which can leach into and poison the water table. Another method of mining lithium is found in Australia, where it is mined from hard rocks instead of the brine found underground. Even this type of extraction is problematic. In addition to the damage to the landscape, it still requires a large amount of water and it is estimated to emit 15 tonnes of CO2 for every tonne of lithium extracted.

While there may be research ongoing throughout the world to try find alternative battery technologies to lithium, which are based on elements that are more abundant in the earth and not as environmentally unfriendly to extract, for the moment, our best and most advanced options are based on lithium, and that is likely to be the case for some time.

A new way of extracting lithium from the ground that has been proposed might prove much greener. We already use geothermal energy to produce heat and electricity, and it is a renewable source with a small environmental and physical footprint. It also doesn’t depend on the sun shining, or wind blowing like other renewable sources. The technique involves pumping geothermal brine to the surface of the earth from deep underground. In some areas, that brine contains high concentrations of lithium, which can then be extracted after the brine has been used to generate electricity. Lithium extracted this way would bolster the supply chain and allow many countries to be self-sufficient in the production of lithium. Lithium extracted from geothermal sources would also require less water and reduce carbon emissions. Consultancy Minviro estimates that only 3m3 of water would be required to extract the same amount of lithium from geothermal sources that would require 170m3 of water from the hard rock method and 469m3 from underground reservoirs. According to the BBC, each litre of brine extracted this way in Cornwall, UK, had lithium concentrations of up to 260 mg. Other brine sources have also been found in the US and Germany with high lithium concentrations.   

 


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