Which Reusable Water Bottle is Most Sustainable?

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Environmental Choices Are Tricky At Times

In today’s society, environmentally friendly choices are quite often straight-forward and pretty obvious, like purchasing a soap bar over a plastic pump dispenser or choosing a bamboo toothbrush over a regular plastic one. 

However, at times, tricky and complex choices need to be made. In this post, we’ll go into the life cycle and carbon footprint for some everyday materials and plastics, to find out which are the most sustainable, and why.

The Water Bottle

Take for example, a simple everyday item, such as the reusable water bottle. The most common types of water bottles available include: plastic, glass, aluminium and stainless steel. With so many options, which one would you go for?

You might be surprised to know that plastic uses the least amount of energy, taking into account total energy use, including mining, transportation and manufacturing. That’s right, the creation of a plastic water bottle has the smallest carbon footprint, when compared to glass, aluminium and stainless steel.

Does this mean plastic is the most environmentally friendly of the four materials? In short, NO! Because the carbon footprint is just one of many environmental impacts that needs to be considered when making everyday decisions.

In this blog, we will examine all the different factors that affect the total environmental impact. We will evaluate which material best lends itself to the reduction of consumption, waste prevention and proactive reuse through a circular economy; known as a closed loop system, where resources are safely returned to nature, or recycled back into systems where they are renewed or reused.

The ‘Total’ Environmental Impact

When making an informed consumption choice based on materials, environmental impacts that must be considered include:

1. How long the material lasts before bio-degradation (i.e its earth life)
2. The impact of the materials debris on living organisms (during earth life and degradation)
3. Carbon Footprint (including, mining of raw material, transportation and manufacturing)
4. Carbon Footprint of the materials recycling process
5. Environmental impact of mining and production
6. Efficiency of materials reuse (how adaptable is it to the circular economy)

Plastic

Plastic Drink Bottles are primarily made from polyethylene terephthalate (PET). Like all plastics, PET is sourced from non-renewable energy sources, petroleum and natural gas. These bottles last 450 years in the environment before they break down. Their impact on natural life is high, as animals and birds (like the Albatross) are known to feed on marine plastic debris, causing a painful death. Whilst degrading in the ocean, microplastics (less than 5mm) are also ingested by smaller marine organisms, including fish, which lead to internal blockages and in some cases death.

The mining impact is also high, as the damage caused by oil spills causes significant environmental damage to coastal and marine ecosystems. One of the biggest recorded oil spills was BP’s 2010 Deepwater Horizon spillage, where over 4 million barrels of oil were released over 87 days, affecting over 2,100km of coastline on the Gulf of Mexico.

Plastic sourced from virgin, raw material has the smallest carbon footprint, when compared to glass, aluminium and stainless steel. However the carbon footprint savings, when taking into account the recycling of the material, is not as significant as aluminium or stainless steel. The different varieties of plastic means the recycling process is problematic as they cannot be melted down together, and therefore must be processed and sorted.

Furthermore, each time plastic is recycled, additional virgin materials are added to improve the quality and integrity of the plastic. The most common types of plastic can only be recycled 2-3 times before its quality degrades to the point where it can no longer be used. The poor recycling efficiency of PET and other plastics makes it non-compatible for a circular economy or closed loop system.

Glass

Glass is comprised of sand, silica and limestone. These non-renewable resources are abundant, and when compared to other materials, the mining impact on the environment is relatively low. Scientists have estimated that glass bottles have an earth life of 1 million years, by far the longest of the four materials. This is because the construction of glass makes it resistant to decomposition, and its impact on living organisms is benign. 

Conversely, glass has the highest carbon footprint, both when manufactured from raw materials and when it is recycled. This is due to the fact that the manufacturing process is power intensive, requiring a furnace at over 2700°C. The heavy weight associated with glass means carbon emissions associated with transport are also high. Glass has a reasonable recycling efficiency and lends itself well to a closed loop system, as it is infinitely recyclable and reusable. However, it has a poor carbon footprint, which is a huge negative.

Stainless Steel

Stainless steel is a steel alloy, composed of steel and chromium. The average earth life for stainless steel is 50 years. Stainless steel debris has little impact on the environment and living organisms, as the majority is easily recycled. Whatever isn’t recycled, does little to no harm to the environment or ecosystems. However, the impact of mining is high, as the mining process creates liquid and solid waste called “mine tailings”. Mine tailings are stored in enormous waste containment facilities, often several square kilometres in size. Recent catastrophic mine tailing collapses have highlighted the issues with the mining process; the most recent taking place in Brazil in January 2019, where 248 people died and 300km of river was contaminated.

Stainless steel is one of the worlds most recycled materials. It is 100% recyclable and it is estimated that at least 80% of all stainless steels are recycled at the end of their life. The nature of steel means it is able to be repurposed and recycled repeatedly, without affecting the quality of the material. The carbon footprint involved in the mining, transportation and manufacturing is high. However, if stainless steel wasn’t constructed from raw materials, and was entirely comprised from recycled scrap steel, energy use would cut by 67%, and CO2  emissions would be cut by 70%. Unfortunately, there is more supply for new stainless steel and not enough available scrap recyclable steel. Yet, stainless still has a high recycling efficiency and lends itself well to a closed loop system.

Aluminium

Aluminium is made from bauxite, and its earth life is 80-200 years. The debris from aluminium has a relatively benign impact on living organisms during its lifecycle. The environmental damage from the mining process of bauxite is substantial. The mining process is both water and energy intensive, producing a variety of pollutants, including bauxite dust, which is hazardous to mine workers and surrounding communities, whilst threatening air, water and land ecosystems.

Although aluminium has the largest carbon footprint when constructed from raw materials, it has the lowest carbon footprint when recycled, equating to a saving of 93% of energy. Aluminium is the ultimate recycling material, and is theoretically infinitely recyclable without affecting its quality. No other material has a recycling process which is as efficient and ideally suited for a circular economy or closed loop system. 

Conclusion

When you take into account the earth life of all materials, the environmental impact of debris, the carbon footprint and recycling efficiency, both stainless steel and aluminium come out on top. Both of these materials are able to be recycled repeatedly, without affecting its quality and integrity, unlike molecular-based materials such as plastics. The 93% energy saving when recycling aluminium makes it the most efficient material for a circular economy or closed loop system. 

Plastic recycling doesn’t “close the loop” as recycled plastic bottles are unlikely to be remade into another bottle. Instead, they are turned into lower-grade plastic products, such as fleece, carpet, toys or even plastic timber. None of these secondary products are in turn recyclable. 

When we manufacture, purchase and later recycle plastic, we are only delaying its eventual disposal. The final destination for all plastic is either a landfill, where it doesn’t decompose, or an incinerator, where it releases harmful chemicals when burned.

At Foodlum, we stand for and advocate the reduction of consumption, waste prevention and proactive reuse through a circular economy. Non-renewable resources should be used sparingly, as the mining, manufacturing and processing causes significant harm to the environment during its earth life and decomposition. When they are used, they should be safely returned to nature or recycled back into closed looped systems where they are reused or renewed. 

So, if you’re in the market for a reusable water bottle, we recommend purchasing in the following order:

1. Aluminium
2. Stainless Steel
3. Glass

We would not recommend purchasing a new plastic bottle, but if you can reuse an existing one, by all means.

Thanks for reading!

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Data, Graph and Table References
https://publications.csiro.au/rpr/download?pid=csiro:EP135565&dsid=DS2
https://ec.europa.eu/environment/integration/research/newsalert/pdf/331na5_en.pdf
http://www.worldstainless.org/Files/issf/non-image-files/PDF/ISSF_Stainless_Steel_and_CO2.pdf
https://www.sciencedirect.com/science/article/pii/S0301421507003655
https://cleanmetrics.typepad.com/green_metrics_clean_metri/2008/08/glass-plastic-or-aluminum.html