Bioprocessing of lithium brines

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Global heating due to greenhouse gas emissions is already disrupting the natural world and human society. We must reduce and eliminate our greenhouse gas emissions to prevent catastrophic climate change. This means generating electricity from renewable sources such as solar, wind and geothermal and using vehicles powered by electricity. As renewable energy sources can be intermittent (e.g. the wind doesn't blow all the time), we need to be able to store the energy generated using batteries. Electric vehicles also need lightweight batteries. Making lots of batteries will therefore be a key part of our transition to a society with low greenhouse gas emissions.Most modern batteries use the chemical element lithium as a main component. Movement of the positively charged lithium through the battery structure stores and releases the electrical energy, meaning that to make many more batteries, we need a lot more lithium. At present we get lithium from two main sources: mining rocks rich in lithium (mostly in Australia) and extracting lithium from salty water (called brine) stored in rocks (mostly in South America). Lithium-rich brines can also be found in rocks in the UK, including in Cornwall, which could be used to give the UK a reliable lithium supply for battery manufacture. These Cornish brines are hot when they are pumped out - as well as containing lithium they are a source of geothermal heat and power from which electricity can be generated. This project will use biotechnology to help recover lithium from geothermal brines. Although technology exists to extract lithium from brine, other chemical elements in the brine can cause scaling (much like in a kettle) in the pipes and clog up the system, which then requires expensive cleaning with toxic chemicals. In this research we will use bacteria that can make chalk-like minerals from the elements in the brine to remove problematic elements at the beginning of the lithium extraction process. After this we will use algae called diatoms to remove silica from the brine to prevent another cause of scaling. We will work with an industrial partner, Cornish Lithium, to build a pilot-scale extraction system of up to 1000 litres to test whether these processes could be used in commercial lithium extraction.This project aims to find new ways in which this biotechnology can contribute to the circular economy. Firstly, we will investigate if we can use waste products (cow urine) to feed the bacteria that make the chalk-like minerals. Secondly, we will test whether the waste materials from the bacteria and diatom treatment tanks can be used to improve local agricultural soils which are nutrient poor and acidic. Finally, we will perform a life cycle assessment to find out how the carbon footprint, environmental impacts, costs and benefits of the system compared with other technologies.