Aluminum can or glass bottle, a textbook case of environmental dilemmas

An aerial view of glass bottles and other rubbish at the entrance to an informal settlement in Johannesburg (illustrative image).

AFP - MARCO LONGARI

Text by: Léopold Picot Follow

6 mins

Faced with the plastic bottle, derided for its impact on ecosystems and global warming, aluminum cans and glass bottles stand out as the obvious heirs.

If the glass bottle is often preferred to the can, the reality is more nuanced and makes this ecological choice a textbook case.

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Earlier this week, an OpinionWay poll for master winemakers in Saint-Tropez claimed that 72% of French people were willing to drink wine from a can rather than a glass.

Here, there is no question of ecology, but rather of convenience: the glass is more difficult to carry, impractical for individual and temporary use, with a higher average capacity than the can.

But from an environmental point of view, is it better to drink your drink in a can, a glass or plastic bottle?

It all depends on the criteria used: metal recycled or not, transport distance, CO2 emissions or impact on wildlife, recycling rate... It is difficult to sort out all these issues, and the solution may be found in a questioning of the system as a whole.

Aluminum is a good student

Contrary to popular belief, glass, often favored over plastic, is not the most ecological solution if it does not come from recycling.

Researchers from the University of Southampton have thus demonstrated that the aluminum can greatly exceeds its competitors and that, surprisingly, the plastic is not so badly placed.

According to their study published in December 2020, for pressurized containers, aluminum is more ecological than plastic and even more than glass.

Ian Williams is one of two authors of the study.

For him, it is clear, " 

 ”.

And it's even better if it's recycled.

The poor score for glass can be explained in particular by the energy expended to produce it.

Very high temperatures are required, up to 1,500 degrees, compared to around 750 degrees for aluminum.

Still, this study could not take into account probable technological innovations: the glass industry is developing high-temperature electric furnaces, and if the electricity used is carbon neutral, the carbon impact of the glass bottle will drop drastically.

Still carbon-intensive recycling

At the end of its life, glass is infinitely recyclable, just like aluminium.

97% recycled in France, bottle glass is virtually flawless, while

for recycling.

If you use a glass bottle, there is therefore a better chance that it will be recycled.

However, the recycling process is also an industrial process.

It takes heat to remelt glass like aluminum, and this heat must be produced in a carbon-free way to limit the impact of recycling.

However, recycling an aluminum can uses only

.

Regulations should also be considered to facilitate the work of recyclers: unlike glass, cans in Europe are sometimes made of two types of materials, a large part in steel and an upper part in aluminium, which makes sorting more complicated.

Also recycled, plastic can be split into pellets to create new bottles.

On the other hand, its recycling gradually reduces the polymer chain that composes it, and it cannot therefore be recycled more than twenty times.

Glass will therefore necessarily end up becoming more ecological than plastic, if it is recycled more than twenty times.

Other criteria to take into account

Another factor to bear in mind, and which is not taken into account by the study because it varies too much depending on the case, is the question of transport.

Once produced, the container must be transferred, filled, then brought to the place of distribution.

However, a glass bottle weighs much more than its can or plastic equivalent.

Under this prism, if it is not moved in low-carbon transport, the glass bottle will therefore be more polluting.

On the other hand, the impact of aluminum in the environment is higher than glass.

Glass being an inert material, it will be ignored by biodiversity, and quickly polished by wind and water.

Aluminum, on the other hand, requires at least 200 years to disappear in nature.

Its impact on health is still controversial: as part of the precautionary principle, it is better to reduce exposure to aluminum as much as possible.

It should also be noted that some aluminum cans contain a thin layer of plastic, to prevent the liquid from coming into contact with the aluminum wall, which could alter the taste and corrode it.

All these considerations taken into account, several choices are available to the consumer.

If you are away from home, you absolutely have to buy a drink, prefer the can or the aluminum container, hoping that they will be among those that are recycled.

If you use a bottle to drink tap water or as a personal container for bulk, prefer glass, which can be reused many times and whose health effects are certain to be nil.

For Ian Williams, co-author of the study, there is, however, another way of looking at things, especially for cans of wine.

“ 

 “, he develops mischievously.

Why do we produce small containers?

Do we really need small doses of various liquids?

Isn't it possible to produce certain products more locally, by setting up a local deposit system and using personal containers?

As is often the case in production, to preserve the environment, it is sometimes more appropriate to change scale and question the dominant paradigm.

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