Aluminum: Advantages and Limitations

With the aim of helping stakeholders make informed choices without succumbing to trends, and after analyzing glass, Gérald Martines* examines the case of aluminum. The considerations for this material are quite similar to those for glass, as it also benefits from a “circular” image due to its high recyclability and relatively efficient collection. “BUT” (!) like glass, it is a material with high energy content and finite resources, and compared to both glass and plastic, aluminum has the highest carbon footprint! Here’s why...

Aluminum, like plastic and unlike glass, can be used to make lightweight packaging, optimizing the amount of material used. For example, to make a 100 ml bottle, you need about 15 grams of PET, 19 grams of aluminum, and 100 grams of glass. However, of these three materials, it has the highest carbon footprint. to take the example of the standard bottles above, as indicative values, the PET bottle will have a footprint of 30 gCO2e, 85 for glass and 150 for aluminum [1].
Aluminum is also the only material, along with plastic, that can be used to make single-material (or virtually single-material) packaging: cans, tubes with aluminum caps, lipstick tubes with aluminum mechanisms, aluminum mirror cases, perfume bottles with pumps (the pump contains plastic, but the whole thing will be detected in the sorting center as aluminum, and during recycling, the few grams of plastic will be vaporized when the aluminum is remelted, as will the protective interior and decorative coatings). .
On the other hand, aluminum packaging is more sensitive than glass or PET packaging to minor cosmetic damage, impacts, scratches, etc., which can be problematic for reusable packaging that is expected to remain attractive over a long period of use.

One of the most recycled and most efficient materials in the world!

Aluminum is one of the most recycled materials in the world and has been for a long time. Unlike glass, it is very efficient to recycle: most of its energy content is used for extraction and initial refining, and it takes 10 times less energy to recycle aluminum than to produce virgin material. Again, for our standard 100 ml bottle, if it is made from 100% PCR, we obtain a carbon footprint of 12 g/CO2e for mechanical rPET, 15 for aluminum, and 67 for glass (note that “luxury” applications typically specify between 15 and 40% PCR, thereby limiting the reduction in carbon footprint achieved through the use of recycled material).

... but can we do better?

However, aluminum is subject to unavoidable limitations in terms of collection and recycling efficiency. Most of these limitations are common to all materials, but some are specific to aluminum. What are they?
When it comes to collection, even in developed economies—which are considered “good students” (or “less bad” students)—collection figures have plateaued. This is not due to insufficient infrastructure, which is widely available in these countries, but rather to user behavior. There is a clear difference between behavior at home and on the go. While sorting waste at home has gradually become the norm, our behavior when we are out and about is quite different. Train stations, metro stations, trains, gas stations, etc. are now mostly equipped with containers suitable for selective sorting, yet they are often used indiscriminately, resulting in mixed contents that would be impossible to sort economically. And street trash cans are single-bin. Packaging associated with nomadic consumption therefore largely escapes collection and cannot participate in the circular economy loop, yet this nomadic consumption has become significant and represents a significant fraction of consumption. Although this phenomenon is fairly widespread, as always in these areas, there are notable differences between countries.
As for recycling itself, a fraction of the material is lost during the recycling process, as with any material, in the form of particles that are too small to be effectively captured.

The limits of recycling!

Each material sees its aesthetic characteristics deteriorate during recycling: glass acquires a slight green tint and PET a gray haze. As for aluminum, its ability to provide highly shiny surfaces deteriorates with recycling, although packaging producers are making significant progress in this area. In all cases, the functional properties are not affected or are only marginally affected—it is the aesthetic aspect, and therefore a subjective and cultural property.
Another factor specific to aluminum is its “dispersive” aspect: unlike glass, which is used almost exclusively in the manufacture of single-material packaging components, aluminum is also used as a minor additive in the composition of plastic or paper packaging components to improve their barrier properties. This is the case, for example, in so-called ‘ABL’ (Aluminum Barrier Laminate) tubes, whose walls consist of a thin layer of aluminum between two or more layers of plastic. It is also the case for many food cartons consisting of a cardboard-aluminum-PE sandwich, or lids for food or personal care product packaging, consisting of an aluminum-PE film. These structures are difficult or impossible to recycle efficiently, and most of the aluminum used in these applications is not recycled.
In the case of cartons, there are a few specific recycling plants in Europe that use a sophisticated system to separate and recycle the three types of materials used in their composition. This process involves several steps: very broadly speaking, the packaging is crushed into flakes, which are then immersed in alkaline baths to recover the pulp fraction. The residue, consisting of aluminum and PE, is then pyrolyzed to recover the PE in the form of gas, which is then reintroduced into the polyolefin production chain, leaving the aluminum, which can then be remelted into ingots. This process allows for the most complete recycling, but very few sites are equipped with this technology, which requires substantial investment and is energy-intensive, especially during the pyrolysis phase, which increases its energy footprint. In the vast majority of cases, only the first stage is implemented, and after recovering the pulp fraction, the rest—a composite of aluminum and PE called Polyal—is most often incinerated or landfilled (although a few marginal uses are emerging, such as making street furniture).

Recycled aluminum is highly sought after... but not very available!

Added to this is another phenomenon, the stock effect: aluminum is a material widely used in the production of durable goods, such as building components (door and window frames, roofs, partitions, furniture, etc.), and with the global construction boom linked to increasing urbanization, this represents a very high demand. Aluminum is also the traditional material used in aircraft construction and a substitute for steel in many applications where weight reduction is sought, such as the automotive and rail industries. For example, the first high-speed trains were built of steel, but when it became apparent that Duplex trains were needed to keep up with increasing demand, they had to be designed in aluminum to avoid adding weight, which would have been prohibitive.
The aluminum used in these projects is thus “stored” for decades. Overall, demand for aluminum far exceeds the recycling flow, resulting in significant and growing demand for virgin aluminum. This has led to the development of new bauxite mining sites; this highly polluting activity is mainly relocated to third world countries, where it is often accompanied by deforestation and loss of biodiversity.
As a result, recycled aluminum is a highly sought-after commodity that is available in quantities well below demand. And when a manufacturer announces that its packaging is made from recycled aluminum and claims a significant reduction in its carbon footprint, this is nominally correct, but, from an overall perspective, they have simply preempted a share of the total amount of recycled aluminum available at a given moment in time, which is then no longer available for other applications, and the overall balance for the community is no better than if they had used virgin aluminum.
In short, aluminum, like glass, is not a renewable material, and, like glass, its resource is finite and exhaustible. What’s more, it is energy-intensive!

Some best practices for aluminum!

Aluminum should certainly be favored for sustainable applications, as its high carbon footprint is then offset by a large number of uses. However, be aware of the risk of visual damage during prolonged use. On the other hand, virgin aluminum should not be used for single-use applications, as this increases energy consumption and CO2 emissions.
For single-use applications, the use of recycled aluminum makes sense because the CO2 footprint is significantly reduced and close to that of polymers, which remain the materials with the lowest footprint.
As for aiming for single-material packaging design, yes, to simplify end-of-life sorting and recycling. Aluminum has an advantage in this respect because of its ability to form “mechanisms.”
Finally, it is better to opt for the largest possible formats, which minimize the amount of packaging vs. the amount of product.

Gérald Martines - IN-SIGNES

*Gérald Martines founded IN•SIGNES to provide companies in the beauty and luxury sector with a wealth of experience in innovation, sustainable development, and business development, gained from 30 years of experience in marketing, design, R&D, sales, and general management roles in several international groups that are leaders in the beauty and design industry.
With a master’s degree in physics, a degree in mechanical engineering, a postgraduate degree in materials science, an MBA, and a master’s degree in prospective studies, Gérald Martines has a 360° view of the various professions, skills, and functions that contribute to strategic thinking on innovation and sustainability.