The energy transition represents a global shift from fossil fuels to renewable energy sources such as solar, wind, and hydropower, driven by the urgent need to address climate change, air pollution, and energy security. This transition, however, intensifies the demand for critical and strategic raw materials required for clean energy technologies, including lithium, cobalt, rare earth elements, and copper. These materials are essential for manufacturing and maintaining technologies like batteries, wind turbines, photovoltaic panels, and electric motors. The European Union (EU) faces significant supply chain vulnerabilities, as the extraction and processing of these materials are heavily concentrated in non-EU countries, such as China. Recycling emerges as a pivotal strategy to mitigate these risks by reducing dependence on virgin resources, enhancing material recovery, and addressing waste streams from clean energy technologies. Current recycling processes effectively handle bulk metals like steel and copper but struggle with emerging waste streams, such as lithium-ion batteries and rare earth magnets, due to technical and economic challenges. This introduction explores the material requirements for four crucial technologies—batteries, electric motors, wind turbine blades, and photovoltaic panels—and evaluates the potential of recycling to secure supply chains and minimise environmental impacts. By analysing trends and policies, such as the EU's Critical Raw Materials Act, the introduction underscores the importance of achieving ambitious recycling targets and fostering innovation in waste management technologies to support a sustainable energy transition.