Things to consider when choosing glass packaging as oppose to plastic
What is glass
- Glass is made from sand, soda ash and limestone baked at temperatures of over 1500oC (~2730oF).
- It requires a lot of energy to make.
- Sand mining and soda ash manufacturing can be problematic.
- It is heavy to transport.
- It is the latter that makes glass environmentally challenging
Carbon costs of glass compared to plastic
a PET (a thermoplastic polymer resin) jar versus a glass one uses twice as much abiotic material (minerals and fossil fuel) to produce and 17 times more water (predominantly from cooling power plants) and produces five times the greenhouse gas emissions. Lucy Seigal writing in the Guardian
But start transporting glass and the figures change
Some calculate this could be as much as 2 tonnes of CO2, per 1 tonne of glass, when transport of such a heavy product is factored in. All this gives glass an Embodied Energy of about 12.7 MJ/kg. (By comparison aluminum is 170 (!!), cement 5.6 and kiln dried sawn softwood 3.4). Treehugger
A PET jar shipped 1,000km in lieu of a glass jar saves 19g of CO2e (carbon dioxide equivalent).Lucy Seigal writing in the Guardian
The weight of three main packaging choices for beverages have big impact on truckload size and thus fuel use.
“For a 335 ml container, the aluminum can is the featherweight at 11 g. The middleweight PET bottle weighs 24 g, while the heavyweight champ of the drink container world, the glass bottle, weighs a comparatively colossal 200 g.
The additional 176-plus grams holds a sizable environmental punch, as fewer bottles can be loaded onto trucks due to weight limits, meaning more trips, and a heavier load uses more fuel. In a German study, researchers calculate that a recycled glass bottle could be the cause of 20 per cent more greenhouse gas than a virgin aluminum can due to its added weight on a cross-country truck journey.
Glass can be recycled indefinitely and into the same product over and over again. Glass lemonade bottles can be made into glass lemonade bottles.
Every tonne of glass saves 225 kg of carbon dioxide.
Plastics degrade during the recycling process. They cannot be made into like for like products (though that is changing), but they can be made into other things. P.E.T. bottles can become fleeces for example.
Glass containers can be easily reused. Sadly this rarely happens and there are limitations. This is from a W.R.A.P. report on the subject.
LCA studies show that the level of benefits refillables have over single use systems is dependent on a number of key factors, e.g. capture rates, transport distances and recycling rates. This stresses the need to view refillables on a case-by-case basis and not simply to promote the wholesale use of refillables irrespective of circumstance.
End User Issues
Glass is also heavy for the shopper. It can be hard work lugging all those jars home. Heavier products are more difficult to manipulate. The elderly and infirm can find glass jars and bottles too bulky to manipulate safely.
Plastic is much lighter and easier to grasp. Glass is slippery.
And of course when it does slip from your trembling hands it can smash in nasty sharp potentially dangerous pieces.
But glass is inert. It does not leach chemicals whereas plastic does. Some consider this to be a potential health hazard.
Many claim that food tastes better when stored in glass. Possibly because there are no leaching chemicals.
Plastic disposable items can easily end up as litter. Because plastic doesn’t biodegrade this is litter with a lifespan of centuries. Plastic waste is damaging the environment and is now a huge ecological threat.
The general consensus seems to be that glass is environmentally better than plastic but only if it doesn’t have to travel too far.
Glass is ideal for bottle reuse schemes such as milk deliveries. You can find one here…