closing material loops

In these problems 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 when it leaves Europe and a recycled raw material when it arrives elsewhere. Almost none of Europe's torn-out window glass returns to a glass factory. The loop exists on paper and breaks in practice.