> According to this paper, glass bottles need to be recycled 20 times in order to reach the same CO2 footprint as a PET bottle This does not support the OP's c

> According to this paper, glass bottles need to be recycled 20 times in order to reach the same CO2 footprint as a PET bottle This does not support the OP's case that "Glass is heavier and causes more CO2 emissions because of the increased energy use for transporting them." There is going to be plenty of transport taking place during those 20 cycles of use and recycle. If the main energy cost of glass is in transport, as he asserted, that's only going to make it less competitive vs. plastic as the number of cycles increases.