Sustainability 101 - Aluminum vs. Steel
We've introduced our range of organic spices in their new SpicePuck containers to help home-chefs to become even better chefs, while also positively impacting the environment. We are posting a series of blogs discussing the environmental impact of our products.
Today’s story is a deep dive into product lifecycle sustainability of two materials ….
We considered aluminum or stainless steel for our SpicePucks and understanding the environmental impact of those two materials was an eye-opening exercise.These two materials are a great example for the importance of assessing the environmental impact across the whole life cycle.
Conventional wisdom says that aluminum is better than steel because its lower weight translates into easier transportation resulting in higher fuel efficiency and therefore lower emissions. That weight advantage applies to the pre-use phase as well as the use phase. If the use phase is long (i.e. cars or small trucks), using aluminum seems like a no-brainer.
However, there are some structural/mechanical advantages of stainless steel (such as higher strength, corrosion resistance, ease of welding, thermal and electrical properties), last of which is higher suitability for food (i.e. not reactive to food) - https://blogs.solidworks.com/solidworksblog/2010/08/lets-go-design-steel-vs-aluminum.html.
Let's dig into the sustainability of both materials some more, starting with the pre-use phase of both materials. Theoretically, both materials can be recycled without losing their properties, i.e. 100% of used aluminum can be recycled into new aluminum without any impact on performance. The same is true for steel.
The reality is that "steel" and "aluminum" are not single elements but contain other materials to achieve specific properties needed for an application. For an overview over the various stainless steel alloys, here is more than you ever wanted to know - https://www.nickelinstitute.org/media/1667/designguidelinesfortheselectionanduseofstainlesssteels_9014_.pdf.
Similarly, for aluminum, there are many different aluminum alloys and grades. For example, an aluminum can used for beverages contains aluminum and also magnesium which makes the recycling easy if that aluminum can is recycled into another can. If the intended use is different, the recycling of that aluminum alloy would require a more complex recycling process. That recycling complexity does not exist for stainless steel. Stainless steel, regardless of the alloy can be recycled for new or changed uses. The "recycling circle of life" for both materials shows that the post use recycling drives the pre-use environmental impact of both materials.
Because of the recycling complexity, most environmental impact comparisons assume a mix of recycled and virgin materials for steel versus only virgin materials for aluminum. All of a sudden, using 0% post-use aluminum versus up to 70% of post-use steel when manufacturing "new" steel or aluminum easily shifts the advantage towards steel.
Steel's advantage is based on the sizeable amount of energy used to turn bauxite into aluminum. In comparison, steel requires less energy during the manufacturing process. So, in summary, steel wins during the per- and post-use phase.
Now, steel's advantage erodes over aluminum's if the use phase of either material involves movement. If the use includes movement and extends for years, hint, hint, a car, the weight advantage (and reduced use of fuel over the lifecycle of a car) makes aluminum the clear, but not undisputed winner - https://www.adandp.media/articles/steel-aluminum-sustainability
Given today's sophisticated design and engineering knowledge, a full aluminum body/chassis uses less gas with the same protection and load capabilities of an older steel car - drivealuminum.org. Needless to say, steel designs have also become much more sophisticated (lighter & stronger) and the argumentation of alu versus steel continues - worldsteeldynamics.com
Our decision, in comparison, was much easier. Our SpicePucks tend to move only within a kitchen, can easily be refilled over and over, do not interact with spice flavors, but feel great in the home chefs hand, stainless steel came out the winner in our comparison.