32 problems carry closing material loops

These are problems where the core challenge is getting materials back into use at their original quality. Six million tonnes of wrought aluminium scrap a year is 'recycled' by melting it into low-grade engine blocks; the same shredded battery powder is legally hazardous waste leaving Europe and a recycled raw material arriving elsewhere; almost none of Europe's torn-out window glass ever returns to a glass factory. The loop exists on paper and breaks in practice.