Lithium chemicals derived from hard rock sources such as spodumene can be more than three times as carbon-intensive as that from brine sources, according to Benchmark Mineral Intelligence’s (Benchmark Minerals’) Lithium ESG Report.
Hard rock sources of lithium currently make up 60% of global mined lithium supply and are forecast to continue to do so through to 2030, according to Benchmark’s Lithium Forecast.
The carbon intensity of the electricity grids where the raw material is mined and concentrated and where the lithium chemical is produced strongly impacts the overall carbon intensity of the process.
The majority of spodumene is mined in Australia where it is processed into spodumene concentrate. This concentrate is then shipped to China where it is processed into lithium hydroxide.
More than half of the emissions associated with producing lithium hydroxide from spodumene come either from China’s electricity grid (27%) or from the energy-intensive production of spodumene concentrate (29%). Both the Australian and the Chinese electricity grids are highly dependent on fossil fuels with a large amount of coal power.
For lithium carbonate produced from brine sources, only 6% of the carbon emissions are associated with the Chilean electricity grid. The largest single contributor to the carbon emissions is the production of soda ash (29%) used to precipitate out lithium carbonate from the brine solution.
Processing hard rock lithium sources is also more water-intensive than that of brines. In almost every metric, lithium chemicals from hard rock sources are more environmentally damaging than those from brine sources, Benchmark finds.
Benchmark’s LCA finds that the production of the chemicals used in the extraction and conversion processes for both brine and hard rock sources are major contributors to many environmental metrics.
The soda ash needed in brine processing, for example, is the most significant contributor to many impact categories assessed by Benchmark’s LCA. Similarly, the sulfuric acid needed in lithium hydroxide production from spodumene contributes 56% towards the ecotoxicity of the process and 39% to human toxicity.
“Both brine and spodumene have serious burdens and risks that need to be mitigated in order to reduce overall environmental burden,” Benchmark’s report finds.
Although lithium chemicals from brine sources are better across the board environmentally, there are strong limitations on where such projects can be developed.
There is actually a limited geographical location in which you can develop a traditional brine project with the right temperature, evaporation rate, and precipitation rate. You’re looking at a year or two just to evaporate your first product.—Cameron Perks, an analyst at Benchmark
Direct lithium extraction (DLE) is a new technology being developed to more efficiently extract lithium from brine sources. Benchmark’s Lithium Forecast suggest the deployment of DLE will encroach on the market share of traditional brine sources over the coming decade and reach more than 16% of the total mined lithium market share.
Given the nascent state of DLE technologies, the environmental credentials compared to traditional brine sources are not currently assessed by Benchmark.
Benchmark’s Lithium ESG Report also found that although the top five miners and the top five converters all produce publicly available ESG reports, only a third of all operating lithium miners and converters do. This highlights a major lack of transparency in the industry.
Benchmark’s Lithium ESG Report provides an independent and detailed assessment of the ESG performance and approach of more than 250 lithium producers worldwide. The Lithium ESG Report is part of our suite of services analyzing sustainability issues in the lithium-ion battery supply chain, along with the Cobalt and Nickel ESG Reports and Life Cycle Assessment (LCA) work.