“Glass bottles could be worse for the environment than plastic, Coca Cola warns”
Source: Telegraph 27 Jan 2019
Many people that I encounter in the green and especially the zero waste community have a strong belief that glass is always better. Some even believe that as long as it’s glass they are in the clear.
If only it was this simple.
The choice of material for bottled beverages in terms of environmental impact is complicated. Factors include materials, manufacturing, weight, transportation, recycling, reusability, and end-of-life disposal. The only thing we can say for sure is that tap water is always the best choice.
But what is the second best choice if you want to enjoy a cold soda, glass of milk, or sparkling water at home or in a restaurant? What’s the carbon footprint of glass vs plastic, aluminium, and cartons?
The answer is not as obvious as you may think.
To make the best choice from an environmental perspective we need to look at the carbon footprint, recycling, end-of-life waste, and transportation.
The carbon footprint of glass vs plastic vs carton vs aluminium
This table summarises different estimates (high, medium, and low) of the carbon footprint of each material:
| 1.5 liter (50 oz) | Glass bottle (single use) | Glass bottle (refilled 30x) | Single use plastic | Carton (e.g. Tetrapak) | Aluminium can (4x 355ml) |
|---|---|---|---|---|---|
| High | 503 g | - | 633g | 60g | 1604g |
| Medium | 323g | 24g | 250g | 32g | 488g |
| Low | 265g | - | 44g | 18g | 259g |
Sources: What is the carbon footprint of bottled water and Tetra Pak.
Recycling of bottled beverage materials incl glass, plastic
This is where it gets more complicated but let’s start with a summary table.
| Glass Bottle | Single-use Plastic | Carton (Tetrapak) | Aluminium can | |
|---|---|---|---|---|
| Carbon Footprint reduction | 26.5-40% | 30% | No data available | 96% |
| How many times? | Infinite for brown color | About 1-2 times, then downcycled | Paper can be reused 4-5 times | Infinite |
| % recovered for recycling | 80% | 9.5% | No data available | 45% |
If aluminium cans are made of 100% recycled material the carbon footprint will be 96% less and thus similar to refilled glass bottles or cartons. However, as only 45% of cans are recovered (in the US) the real carbon footprint is much higher. In countries such as Germany and Sweden with deposit schemes, the recovery rate is much easier and higher and therefore aluminium can be an environmentally sound choice.
Until recently recycled plastic bottles were rarely made into beverage containers again. Instead, they were downcycled into other plastic goods. On average less than 20% of a PET bottle produced in Europe is made from recycled plastic. With better materials and manufacturing the big beverage makers (Coca-Cola, Nestle, Pepsico, etc) are now changing this but the change is slow and the efficiency will vary by country.
Transportation of bottled beverages
Transportation is often what makes glass the losing material. Not only does it have to be transported to the bottling facility and then to the consumer. Once consumed it has to be collected and transported back to the bottling facility.
A 500ml glass bottle weighs about 400g, but a comparable 500ml PET bottle, carton, or aluminium weighs about 10g. While that might add up to a little annoyance for the consumer, that 40 to 1 weight ratio is a very big problem for manufacturers and distributors. It means more wear and tear on packaging machinery, less efficient shipping and distribution, and, as a result, higher fuel costs and emission responsibility.
The summary table in this article assumes local bottled water is transported a short distance to avoid distorting the data.
Waste Management of glass vs plastic vs carton vs aluminium
Last but not least is what happens at the end of life of each material if it’s disposed of in a landfill, or nature, or ends up in the oceans. It’s painfully clear today that even though plastic might have a lower carbon footprint than glass the biggest polluter is plastic. We talk about plastic pollution in our oceans and not glass or aluminium.
* The New Hampshire Department of Environmental Services estimates that it takes 1 million years for a glass bottle to decompose in the environment, with conditions in a landfill even more protected.
** TetraPak (and other brands) which are also referred to as multi-layer boards, or cartons, are actually composites of many materials. Most commonly they consist of a few basics such as paper (70%), aluminium, and various plastics. Don’t be surprised at finding 12 or even 16 different layers of materials making up one board. This makes it difficult to recycle so depending on the country these may not be separated for recycling.
Conclusion about glass vs aluminium vs plastic
Just tell me what to choose!
Ok. Here’s the list in order from best to worst:
- No container – drink tap water, draught beer, sparkling water from a soda maker, homemade juice, or whatever you can pour in a glass or carafe
- Refillable glass bottles or plastic bottles (where available) or Carton Packages (in countries with good recycling systems)
- Recycled aluminium cans (depending on the country)
- Recycled or non-recycled single-use PET (in countries with good recycling systems)
- Single-use glass bottles
It should be noted that this is simplified. In countries that have a poor recycling system, single-use glass bottles tend to be better for the environment than plastic, carton, or aluminium Also, the carbon footprint of glass vs plastic, carton, and aluminium differs between products, countries, and other circumstances.
For drinking water there is no excuse to use any kind of container (plastic, glass, aluminium, or carton). If you don’t like the taste or worry about the quality of your tap water use an affordable water filter like EcoPro with almost zero plastic residue.
Does this answer your questions about plastic vs glass vs other materials? Agree or disagree? We want to know so that we can improve the data of our research, conclusions, and recommendations. E-mail me at magnus@tappwater.com.
Also, read our blog about the most sustainable bottled water.
Questions, comments, and other details
While writing this article we spent a lot of time researching the topics. Here are answers to some of the most common questions and more material.
Where does the Carbon Footprint data come from?
Most of the data is sourced from our in-depth meta-analysis of the carbon footprint of bottled water. In addition to this, we added specific data on carton containers to this blog sourced from Tetra Pak as well as aluminium recycling.
What do others say about the best choice of beverage container?
Treehugger
A comparison by treehugger concluded that a tetrapak of milk has a considerably lower carbon footprint than reusable glass bottles due to material and weight. The challenge though is whether the tetrapak can be recycled which depends on where you live. The total greenhouse gas emissions for the manufacture of the packaging and the transportation, all other things being assumed equal, are 265 grams for the glass, 101 grams for the plastic jug, and 32 for the tetrapak. If the glass is reused 30 times it gets closer to tetrapak but that excludes the collection and transportation back to where the milk is produced.
And as per Tetrapaks own reports the CO2 footprint of cartons may be even lower at 18-60 g cradle to cradle for a litre of milk.
International Bottled Water Association
It doesn’t come as a surprise that the bottled water association recommends and defends the use of PET. Here’s a summary of the carbon footprint data on bottled water prepared by IBWA.
If glass bottle refill schemes are so good why doesn’t everyone use them?
We looked at the pros and cons of the systems used in Germany, Sweden, Denmark, and Norway. When they were implemented 20+ years ago they were extremely efficient. However, since then the share of refillable glass bottles has gone down considerably. The reasons include cost, weight (transportation), convenience, fragility vs plastic, and improvements in plastic materials.
The general view from the governments in these countries seems to be that plastic managed well can be as good as glass. With recycling, downcycling, and incineration plastic has a similar carbon footprint and does no harm to the environment.
Another alternative could be reusable plastic containers like they have in Germany. But these materials are also expensive and most plastics leach plastics over time. This means more microplastic and other chemicals in our bodies.
What about the carbon footprint of glass recycling?
The advantage is that glass can be recycled almost infinite times. At least with non-clear glass. Also, the cullet has a much lower melting temperature than its original constituents and therefore requires around 40% less energy to create the molten glass that forms the containers.
According to a study conducted by the Waste and Resources Action Programme (Wrap), switching from clear glass to green cuts packaging-related CO2 emissions by 20%. This is due to the higher recycled content in green glass bottles, which is as much as 72.4%, against an industry standard of 28.9%.
Reusing a glass bottle three times lowers its carbon footprint roughly to that of a single-use plastic beverage bottle. Source: Researchgate Life Cycle Environmental Impact of Carbonated Soft Drinks
Germany refill system – the great recycling example?
According to a recent Spiegel article, at the time the law came into force, 64% of all bottles purchased were refilled i.e. were multi-use bottles. At the end of 2012, this had reduced to 46%, with the trend heading downwards. In early 2015, Coca-Cola announced that it would over time phase out multi-use bottles in favour of one-time use, citing the high logistics costs of collecting the multi-use bottles and holding free storage space for them.
93.5% of PET bottles were collected for recycling in 2016. Only 34% of German PET bottles are made of recycled plastic. The rest is new oil-based materials.
Norway's reusable bottle scheme
Norway used to have a recyclable bottle scheme for the reuse of bottles but gave it up in 2013. Norway got rid of deposits for reusable bottles in 2014, while in Germany the two systems still exist side by side.
More sources to evaluate glass vs plastic vs aluminium vs carton:
- Carbon footprint of recycled Aluminum vs glass – https://amp.slate.com/articles/health_and_science/the_green_lantern/2008/03/wear_
green_drink_greenly.html?via=gdpr-consent - The German glass bottle reuse system – https://liveworkgermany.com/2017/05/how-does-the-german-pfand-system-work-and-is-it-effective/
- German glass bottle use and reuse going down – http://www.spiegel.de/wirtschaft/service/mehrwegflaschen-einwegflaschen-im-pfandflaschen-wirrwarr-a-1031491.html
- Norway vs Germany recycling systems – https://www.dw.com/en/plastic-bottle-recycling-
champion-norway-or-germany/a-4488042