Metals for low-carbon technologies: Environmental impacts and relation to planetary boundaries
Vanessa Schenker, Viktoras Kulionis, Christopher Oberschelp, Stephan Pfister
Abstract
Low-carbon technologies are needed to mitigate the impacts of climate change but require large amounts of metals, whose mining and processing cause a broad range of other environmental impacts. These require sound assessment to prevent burden-shifting. One assessment approach for that is the Planetary Boundary framework which acts as a guidance system for maintaining the stability of the Earth. This framework is still under development and has so far only been applied in a few several sectors, not including the metal sector. The environmental challenges of the metal sectors are unique, the adaptation potentials of existing work have not been investigated and the specific data and methodology gaps are unclear. Hence, this paper reviews the current knowledge as well as the open research gaps of the critical planetary boundaries (including for example climate change, biodiversity integrity, freshwater use) related to the metals required for low-carbon technologies. To complement that perspective, life cycle assessments stress the relevance of fine particulate matter formation as well as toxicity impacts, with the related planetary boundaries (atmospheric aerosol loading and introduction of novel entities) being the least developed ones. The interplay of different scales of planetary boundaries like on regional or global level will need further assessment. Finally, we consolidate our findings to formulate the research objectives that will complete the mapping of the metal sector onto the Planetary Boundary framework.