Future environmental impacts of metals: a systematic review of impact trends, modelling approaches, and challenges

Abstract

Abstract

With the energy transition, the future demand for many metals is expected to sharply increase. We systematically reviewed studies which assessed future environmental impacts of metal supply chains. We evaluated their results regarding future impact trends, and their methods, i.e., modelling approaches, scenario variables, and data sources.

Our review yielded 40 publications covering 15 metals: copper, iron, aluminium, nickel, zinc, lead, cobalt, lithium, gold, manganese, neodymium, dysprosium, praseodymium, terbium, and titanium. Metals crucial for the energy transition, e.g., lithium or neodymium, are rarely addressed, unlike major metals. Results for future environmental impacts of metals strongly depend on scenario narratives and assumptions. We found that specific impacts (per kg) may decrease driven by, e.g., greener electricity, higher recycling shares, or novel technologies. Nevertheless, this is probably insufficient to compensate for surging demand. Thus, future demand-related impacts are still likely to increase. We identified 15 scenario variables. The most common variables are background electricity mix, ore grade, recycling shares, demand, and energy efficiency. It is crucial to better understand future impacts of more metals, considering also rising demand and impacts beyond GHG emissions. We recommend improving research practices towards open and collaborative research, to enable more harmonised, reusable and accurate scenario assessments. Highlights Metal production causes severe environmental impacts, that may increase in the future when demand for metals may rise.We found that, e.g., greener electricity, higher recycling shares, or novel technologies may reduce impacts per kg metal.Yet, this is probably insufficient to compensate for rising demand. Thus, demand-related impacts are likely to increase.Knowledge is lacking about future impacts of many metals, especially minor metals essential for the energy transition.Better understanding of future impacts of metals is needed, considering rising demand and impacts beyond GHG emissions. Data availability Our dataset summarises the state-of-the-art of metal scenario modelling in prospective LCA including all data sources used per publication. It is openly available in a Zenodo repository to facilitate and accelerate future research: https://zenodo.org/doi/10.5281/zenodo.10066583