[asdff]

Depends how you power the glass factory. It certainly can if you use coal or gas.

[chairmansteve]

Natural gas is clean, apart from CO2. And if the glass is reused, you don't need so many factories.

[asdff]

I forgot about leaving bottles for the milk man. Certainly a more expensive way of doing business than a one off bottle you don’t have to collect and clean though.