Slowing, narrowing, and closing material flows: Impacts on metal demands in wind and solar power

Ambitious electrification and decarbonization targets will increase demand for metals used in renewable electricity technologies. Circular economy strategies have been proposed to curb this demand, but the combined impacts of longer design lifespans, material-intensity reductions, substitution, and recycling—strategies that slow, narrow, and close material flows—remain unquantified. Here we estimate the quantities of germanium, gallium, neodymium, praseodymium, dysprosium, and terbium required for a large-scale deployment of wind and solar power in Sweden through 2050. We then assess how these strategies affect material demand. We find that across metals, their combined implementation can reduce cumulative primary metal demand by 52–60% for wind and 55–72% for solar power, substantially lowering dependence on primary production. Strategies that narrow material flows demonstrate the greatest reduction potential. Nevertheless, primary demand persists for most metals through 2050, indicating that additional primary or other secondary supplies will still be necessary. The impact of circular economy strategies is metal-, technology-, market-share- and time-dependent. Therefore, no single strategy fits all contexts, instead tailored portfolios are needed to reduce metal demand. A trade-off emerges within the transition period to 2050: a combination of strategies that most reduce gross metal demand can increase primary demand. This trade-off requires industrial and policy decision-makers to choose between minimizing the total material throughput or the reliance on primary supply. Ultimately, tailored portfolios of strategies that slow, narrow, and close material flows are essential to reduce metal demand and support the transition to a renewable electricity system.