(For ‘oil’ read ‘fossil fuel’)
It occurred to me that if a time traveller from 1960 could be plunked down into our time, one of the first thing s/he’d notice might be the ubiquity of plastic. Milk and most other beverages come in plastic. The famous glass Coke bottle is long gone, to give only one example. Medecine bottles are all plastic now, as are many, many other things.
With most plastic coming from ultimately from oil, how much does that affect our consumption? Could we save on oil consumption by going back to glass? Or does it cost more energy to convert silica to glass, so we would end up not saving anything?
Well, IIRC my basic science training, plastics are made from what is left after the fuels have been fractioned off. So I don’t think it would save us any oil to switch back to glass. That, and as you alluded to, the fuel used to transport and recycle glass can be significant. Does any engineer out there have the exact figures?
I don’t have any exact figures, but I did here on This American Life that recycling plastic is quite the good deal, whereas recycling glass is rougly equivalent to making a new glass bottle (except that the used glass doesn’t end up in the landfill.)
Consider: To make a new bottle, you take some sand (which is quite plentiful), apply a lot of heat to liquify it, then shape it.
To make a recycled bottle, you bust up some old bottles into fine particles, apply a lot of heat to liquify it, then shape it.
Plastic containers weigh much less than equivalent glass ones. Shipping plastic containers around will use much less fuel than glass requires.