Lithium extraction from geothermal brines

Mining companies are excited about the prospect of mining vast amounts of lithium through lithium extraction from geothermal brines. This is a potentially low carbon and environmentally friendly way to meet the demand for lithium that is used in modern technology. 

What is lithium and what is it used for?

Lithium is a fascinating metal. It is light and solid at room temperature (Live Science). It melts at 180.5 degrees celsius and boils at 1342 degrees. Typically a white-grey powder, it flares red when alight. Lithium is found in minerals and salts. Lithium salts have been used for years to treat mania and depression. 

Lithium is also used for modern technology. It is used in batteries – lithium-ion batteries are used in smartphones, laptops and desktop computers. They are used in aircraft. And for electricity storage batteries used for renewable energy. They are also used for electric cars. 

This means the demand for lithium is rising fast. In 2021, demand for lithium increased by 36% to 540,400 tonnes (Reuters). It is expected to reach 3 million tonnes by 2030. Where is all the lithium going to come from?

Where do we get lithium?

Lithium makes up only 0.0007 percent of the earth’s crust. To date it has mostly been mined in hard rock mines in Australia or underground brine reservoirs in Chile and Argentina. Increased demand means that mining companies are looking for new sources. 

A rich source of lithium was discovered in Cornwall in the mid 1800s (BBC). It was bubbling out of a copper mine. The miners bottled and tested it, only to discover it had up to ten times the normal amount. But no-one had any use for it. Now, there are many commercial reasons to tap into this motherlode. 

The environmental impact of lithium

The low environmental impact of lithium extraction from geothermal brine is an extremely attractive prospect. It is estimated by Minviro as zero emission, in comparison with hard rock mining at 15,000 tonnes of Co2 and 5,000 tonnes from underground brine reservoirs, per tonne of lithium. The water required to extract lithium from hard rock mines is nearly sixty times that of geothermal brines (170 cubic metres vs 3 cubic metres). Added to this, geothermal water requires very little land – approximately 1 cubic metre per tonne of lithium. 

Cornish Lithium are working, with the backing of the UK government, on extracting the lithium from sites in Cornwall. The project has been helped by the extensive mining maps of the Cornwall area which have helped to identify the best places to mine. The aim is to extract the lithium while at the same time producing zero carbon heat and power. 

Last week, Cornish Lithium announced a collaboration with Northern Lithium to supply the UK’s requirements (Northern Echo). Despite these new developments the UK and Europe will likely remain dependent on imported lithium for the foreseeable future (The Guardian). 

We rely heavily on minerals to produce renewable technologies and lithium is essential for solar power and clean energy storage, as well as powering our smart devices and our electric cars. The increased demand for lithium is driving prices up and so it is more important than ever to find new sources that are environmentally friendly. Geothermal brines, rich with lithium are a potential answer if the extraction process is clean.

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