## Questions ## Does recycling save energy? Apparently so for aluminium: this takes around 54 MJ/kg to produce from ore (cf. [Wikipedia](http://en.wikipedia.org/wiki/Aluminium#Production_and_refinement)), while recycling takes [roughly 20% of the energy](http://en.wikipedia.org/wiki/Aluminium#Recycling). For comparison: coal provides around 28 MJ/kg (again, cf. [Wikipedia](http://en.wikipedia.org/wiki/Energy_density)). What about glass? What about other materials? Of course, there are other reasons why recycling might be a good thing: reducing pollution from landfills, needing fewer bleaching chemicals for paper and card, etc. However, it would be nice to assess it from a saved energy point of view. Unfortunately, it seems that many criticisms of recycling come from economists criticising it on the basis of a higher monetary cost than landfill, rather than on other more physical criteria.