The transition to a low-carbon economy will be material-intensive. Production of these materials (from mining to manufacturing) incurs environmental costs that vary widely, depending on the geology, mineralogy, extraction routes, type of product, purity of product, background system or manufacturing infrastructure. Understanding the impacts of the raw materials underpinning the low-carbon economy is essential for eliminating any dissonance between the benefits of renewable technologies and the impacts associated with the production of the raw materials. In this Review, we propose an integrated life cycle assessment and geometallurgical approach to optimize the technical performance and reduce the environmental impact of raw material extraction. Life cycle assessments are an effective way of understanding the system-wide impacts associated with material production, from ore in the ground to a refined chemical product ready to be used in advanced technologies such as batteries. In the geometallurgy approach, geologists select exploration targets with resource characteristics that lend themselves to lower environmental impacts, often considering factors throughout the exploration and development process. Combining these two approaches allows for more accurate and dynamic optimization of technology materials resource efficiency, based on in situ ore properties and process simulations. By applying these approaches at the development phase of projects, a future low-carbon economy can be achieved that is built from ingredients with a lower environmental impact.

Most critical raw materials, such as the rare-earth elements (REEs), are starting products in long manufacturing supply chains. Unlike most consumers, geoscientists can become involved in responsible sourcing, including best environmental and social practices, because geology is related to environmental impact factors such as energy requirements, resource efficiency, radioactivity and the amount of rock mined. The energy and material inputs and the emissions and waste from mining and processing can be quantified, and studies for REEs show little difference between ‘hard rocks’, such as carbonatites, and easily leachable ion-adsorption clays. The reason is the similarity in the embodied energy in the chemicals used for leaching, dissolution and separation.

Rare earth elements (REE), including neodymium, praseodymium, and dysprosium are used in a range of low-carbon technologies, such as electric vehicles and wind turbines, and demand for these REE is forecast to grow. This study demonstrates that a process simulation-based life cycle assessment (LCA) carried out at the early stages of a REE project, such as at the pre-feasibility stage, can inform subsequent decision making during the development of the project and help reduce its environmental impacts. As new REE supply chains are established and new mines are opened. It is important that the environmental consequences of different production options are examined in a life cycle context in order that the environment footprint of these raw materials is kept as low as possible. Here, we present a cradle-to-gate and process simulation-based life cycle assessment (LCA) for a potential new supply of REE at Songwe Hill in Malawi. We examine different project options including energy selection and a comparison of on-site acid regeneration versus virgin acid consumption which were being considered for the project. The LCA results show that the global warming potential of producing 1 kg of rare earth oxide (REO) from Songwe Hill is between 17 and 87 kg CO₂-eq. A scenario that combines on-site acid regeneration with off-peak hydroelectric and photovoltaic energy gives the lowest global warming potential and performs well in other impact categories. This approach can equally well be applied to all other types of ore deposits and should be considered as a routine addition to all pre-feasibility studies.

Rare earth elements (REE) have a broad and expanding range of uses in low carbon energy technologies, from wind turbines, to batteries, catalysts and electric cars. Concerns about the future supply...