Digesting fossil infrastructure for cleaner energy transitions

The climate crisis mandates building renewable energy infrastructure faster, which increases demand for primary materials with large environmental footprints. Recycling can mitigate such impacts, but its potential depends on waste availability. Here, we use life cycle assessment and monetization of impacts to explore the environmental implications of recycling fossil infrastructure that may become obsolete during the transition. Among many materials in fossil infrastructure, recycling steel is particularly noteworthy, as its stock (1.35 Gt) aligns with projected demand for the energy transition. Recycling steel could save up to 1.85 Gt CO2,eq emissions and $5.20 trillion in externality costs while remaining competitive with current production methods. It would also reduce the carbon footprint of wind and photovoltaic power by one third. These findings provide strong evidence for the benefits of repurposing fossil infrastructure and underscore the need for policies to expedite the transition while addressing socioeconomic and geopolitical issues.