Big Fat Bottle – © rcphotostock (13176)

Is the ecological superiority of the returnable glass bottle just a myth?

The lightweight returnable PET bottle offers quite a lot of benefits.

The returnable glass bottle is often presented as being exemplary when it comes to discussions on sustainable beverage packaging. The reasoning is that the thick glass bottle is repeatedly washed and then refilled, so it is not a ‘single use’ bottle.

The days of the throwaway society have rightly come to an end. But does the widely held positive view of the ‘big Bertha’ among beverage containers stand up to closer scrutiny? Scientific studies have arrived at significantly more differentiated assessments.

Dr Isabell Schmidt, managing director of the German Association for Plastics Packaging and Films (Industrievereinigung Kunststoffverpackungen) criticises the self-evident manner in which outdated prejudices are constantly being rehashed in debates on packaging: “Returnable beverage bottles have such a good reputation that their life-cycle assessment is often no longer questioned.” An example is the myth about the ecological superiority of the returnable glass bottle. Even the most recent representative life cycle assessment by the German Federal Environment Agency (UBA) covering the packaging of mineral water and soft drinks ten years ago did not produce a clear result.

Since then experts, at least those that are neutral, have been in no doubt that only under very specific, narrowly defined conditions is the so-called ecological footprint of returnable glass bottles better than that of returnable plastic bottles – or PET bottles to give them their proper name. Transport logistics is the ecological Achilles' heel of returnable bottles. This is because it plays a decisive role in determining which returnable beverage packaging is the more sustainable.

Transport distances are decisive

In its impact assessments, the UBA basically found – to the surprise of many – that single-use glass bottles are the worst of all beverage packaging variants in terms of ecology and sustainability. According to the report, the life cycle assessment of the glass bottle only improves if it is refilled as often as possible and not transported too far. The question of transport distances is also decisive for the ecological footprint of returnable packaging: the greater the distance a beverage travels to the consumer, the greater is the ecological superiority of the returnable PET bottle over its glass competitors. This is because the glass bottle is heavier. The further the glass bottle has to be transported, the greater is the amount of fuel required and thus the quantity of emissions released. As consumer organisations also admit, the glass bottle only has a slight advantage over the PET bottle when the race to be the most eco-friendly bottle is run over short distances. It is a situation that does not usually arise in practice, though. Consumer advisors therefore emphasise the ecological benefits of returnable versus non-returnable packaging, rather than of one packaging material over another.

The mantra of the glass bottle being the only true ecological container is nevertheless still being repeated in the debate on sustainable beverage packaging – without taking the facts into account, as experts critically point out. Such facts also include the 70 per cent target for returnable packaging introduced in 2019, which is expected to massively increase transport volumes by the end of 2021, with all the negative consequences for road traffic and the environment. Against this background, neutral observers believe it would make more sense to use the most favourable packaging for beverages transported over long distances. And that is not the glass bottle, as documented by life cycle assessments.

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