Along with many other countries worldwide, the UK is committed to achieving a low carbon economy. There is a plan to achieve net zero carbon dioxide emissions by 2050, with a key component of this plan being a ban on the sale of new petrol and diesel cars by 2035, and a switch to electric vehicles. These vehicles will require storage batteries that contain many components made of metals that have limited supplies. For example, a recent open letter authored by Professor Richard Herrington (principal investigator for the NHM on this proposal) explained that if the UK is to meet its electric car targets, it will require three quarters of the world's current total annual production of lithium - an essential component of modern electric vehicle batteries. Whilst current rates of lithium production are sufficient to meet global demand, we need to investigate additional lithium resources if we are to meet greenhouse gas emission targets. This proposal seeks to better understand the Earth system processes that concentrate lithium into mineral deposits, from which lithium can be mined in both an economically feasible and an environmentally responsible manner. Our central hypothesis is that major lithium deposits are largely formed in parts of the world where continental collision occurs as a consequence of plate tectonics.
We will further test the hypothesis that within these collisional environments there is a "life-cycle" of tectonic processes that is reflected in the formation of different types of lithium deposits. Broadly speaking, in the first stage lithium is moderately concentrated in igneous rocks that are formed in this setting. Lithium is a relatively soluble element, which is readily leached and weathered from these rocks (particularly by hot geothermal water) and the lithium-rich waters may accumulate in basins that are also formed during continental collision. If the climate is arid, the waters evaporate to form a lithium-rich brine that can be an economically viable lithium deposit in its own right. In these brine basins, complex chemical processes and extreme microbial life may play a role in cycling elements and concentrating the lithium into sediments. Over time, the geothermal and volcanic activity ceases and the lithium-rich sediments may be buried and thus preserved for millions of years. Subsequently, these buried rocks may also serve as a source of lithium that can be extracted. With further burial and then heating, these lithium-rich sediments can reach temperatures at which they undergo melting and the formation of lithium-enriched pegmatites and granites. Again, these rocks may contain sufficient concentrations and amounts of lithium to represent a source of lithium that can be extracted for ultimate incorporation in electric vehicle batteries.
At each stage of the life-cycle there are uncertainties regarding the source of lithium, and how it is transported and trapped. The different types of lithium deposits also vary in how easy it is to extract the lithium, and we need to consider how to do this in an environmentally responsible way. We will tackle these problems by bringing together a group of scientists who have considerable expertise in all aspects of this lithium journey. We will use a wide range of techniques, from simple geological observations through to highly sophisticated isotopic analyses and microbiological techniques, to track the behaviour of lithium. We will work alongside industry partners to identify the types of deposits that can be profitably extracted while simultaneously minimising any damage to the environment, and we will investigate the potential for more sustainable methods of lithium extraction using microbial processes. We anticipate that our research will provide industry with new targets for exploration for lithium resources. This will not only help secure a low carbon economy for the UK, but also provide important economic benefits to the UK and other nations.