 Rare earths are used in renewable energy technologies, but their availability has declined due to Chinese government quotas and illegal mining operations, leading to increased prices. There are only a few operating mines worldwide, including by an OBO in China, Mountain Pass in the US and Mount Weld in Australia. The major contributor to the GHG footprint of rare earth processing is hydrochloric acid, followed by steam use and electricity. Life cycle-based water and energy consumption is significantly higher compared with other metals. This article was authored by Nashead Hack, Anthony Hughes, Seng Lim, and others.