Aluminum versus Glass versus Plastic
While EcoEnclose focuses on sustainable packaging for ecommerce, we often get questions about primary product packaging. Specifically, we are asked questions like "If I'm trying to go plastic free, should I choose glass or aluminum?" and "How can I make sure my primary packaging is as sustainable as my shipping packaging?"
Here we provide a comparison between three materials commonly used for product packaging - glass, aluminum and plastic. These options exist in everything from beverages to skincare to nutraceuticals - and we know many companies we work with are struggling to choose between them.
Bottom line: 100% recycled aluminum takes the gold. If you can find and use 100% recycled, curbside recyclable aluminum packaging go with it as the most sustainable choice. But, when recycled isn’t feasible (unfortunately aluminum with very high levels of recycled content is not common), the answer gets trickier. Surprisingly, plastic options often edge out glass and aluminum alternatives as they have a lower carbon footprint and emit fewer pollutants.
When comparing materials side by side, you'll want to consider a few factors:
- The sustainability of the source material and the impact of producing and extracting that source material. Aluminum, glass and plastic are all made from non-renewable extractive resources, so a deeper dive into the impact of their mining and the resources required to convert them into their final form is valuable.
- Transportation of the source material and packaging across the supply chain, including the last leg of the journey to the customer
- The end of life of the packaging, including the likelihood of it being reused, the likelihood and impact of it becoming litter, the impact of the material in a landfill, and the likelihood and impact of it being recycled.
Aluminum: The source material for aluminum is a rock called bauxite. Mining bauxite can devastate ecosystems, generate air and water pollution, and cause health issues for the surrounding communities. Crushing, heating and converting bauxite into aluminum is also extremely energy-intensive and polluting. One study showed that it required an estimated 1.09 kilowatt-hours of energy to manufacture a glass bottle versus 2.07 kilowatt-hours of energy to manufacture aluminum from raw bauxite. The interesting thing about aluminum, however, is that once the material is created, it is extremely efficient to recycle and is endlessly recyclable with no degradation of quality. In fact, recycled aluminum has been shown to be 96% more energy and carbon efficient than virgin aluminum. Because aluminum is so lightweight, it is efficient o transport - more cans can fit into a smaller space and their light weight means less gas is needed. And because aluminum isn’t fragile, less packaging is needed for transport. Aluminum also has the best nd of life outcome - 65% of aluminum packaging is recycled (and it is the most desired material at a MRF because aluminum fetches high prices).
Glass: Glass is made from sand, soda ash (naturally occurring sodium carbonate) and limestone and a bunch of additives. Sand is actually the most mined mineral in the world (largely for concrete), responsible for 85% of mineral extraction. It is also the least regulated, and is destructive and corrupt. Limestone is typically mined from a quarry and has been shown to contaminate water and contribute to noise pollution, and destroy animal habitats. As noted above, it is energy intensive to convert raw materials into glass, but not nearly as intensive as aluminum. However, glass recycling is less efficient than many other forms of recycling, due to the processing required to return glass to a usable, raw state. According to the EPA, recycled glass requires only 30% less energy than virgin glass. Additionally, glass is heavy and fragile, making the transport and storage of glass packaging more energy intensive than aluminum and plastic. Finally, while glass is technically endlessly recyclable, glass recycling in the US is actually fraught with issues and our recycling rate for glass is just about 33%. One positive for glass is that it is more likely than aluminum and plastic to be reused before being recycled or landfilled (though the vast majority of glass bottles are still only used once).
Plastic: Traditional plastic is made with oil and natural gas. Bio-based plastics are rising in popularity but they still represent a tiny fraction of the industry, and they are typically grown in ways that heavily rely on fossil fuels. Fossil fuels are converted into smaller pieces, called monomers, and are then chemically bonded together to create long chains, known as polymers. These polymers are the plastic you see in the form of water bottles, food packaging, and much more. The destructive nature of drilling oil and gas is fairly well understood among environmentalists. However, it is more energy efficient to convert fossil fuel into plastic as it is to produce aluminum or glass. Additionally, researchers in Southampton recently found that glass has higher negative contributions to climate change, freshwater and toxicity, ocean acidification and eutrophication than plastic. Additionally, plastics recycling is fairly efficient - recycled plastic requires 65% less energy than virgin plastic. Like aluminum, plastic is also lightweight, making it efficient to transport and store. Where plastic really fails compared to glass or aluminum is at the end of life. The EPA has found that just 9% of plastic in the US is recycled each year (though rigid plastics like PET bottles have a 29% recycling rate - similar to glass). Additionally, currently, plastic can only be recycled a handful of times before reaching the end of its useful life. Because of this, our current recycling processes tends to downcycle plastic into durable goods like composite lumber rather than turning bottles back into bottles.
It is important to remember that no material is "sustainable." This is especially true when debating between plastic, aluminum and glass - three non-renewable, extractive options. So, when choosing between these three, a critical step you can take is to maximize recycled content, maximize reuse, and maximize recycling when reuse is not an option.
Sources and additional reading