Shouldn't We Make Everything out of Stainless Steel? Uh... No! Part 1.
You can imagine that the Buoy crew gets into some pretty deep conversations about reuse, recycling, materials and carbon impact with sustainability officers and other folks who know what they are talking about. In such situations, we often have a commiserating huddle over the stainless steel fetishists who want everything to be made from that wonderful metal. (I began my career working in pharmaceutical companies where everything is made of or clad in stainless, so I sympathize with the obsession.) At the risk of ruining the ending, exalted thoughts about the sustainability of stainless steel are not supported by fact or projections of future production. To get to a point of stainless-only optimism, you have to make some unrealistic assumptions about how much steel recycling is happening how soon, under what conditions steel is made and, most importantly, you must compare your sky-high assumptions about steel recycling to virgin, unrecycled plastic.
Before we get too deep into the numbers, let's look at a good overall survey of the topic, one we will return to in other installments of this newsletter, namely, McKinsey and Company's Climate Impact of Plastics report from July 2022. You can read a few key pages at that link and download the whole report for free if you sign up with them. The summary of the report is given at the top, with the conclusion that "plastics have a lower total greenhouse gas contribution than alternatives in most applications." Specifically, in the 14 applications across food service, automotive, construction, fashion, and others, the only application where plastic was not a lower-carbon emitting material was for the 55-gallon drum. Metal is better in that case by 30%. For EVERYTHING ELSE, plastic is a lower carbon solution and they are not even comparing it to something like a Buoy product with a supply chain designed to reduce carbon and environmental impacts. They are talking about virgin plastic with no recycled component. (If you distrust McKinsey, thinking they are likely to be a conservative shill for oil interests, here's an article from NPR that uses different sources to conclude that plastic is the lowest carbon impact material amongst alternatives.)
Having this conclusion dropped on you cannot be satisfying without some intuition to back it up, so let's try to create that intuition: Steel melts at around 1500°F while plastic melts around 300°F. So when you set out to melt the metals to make steel, you are burning a lot more fuel. And it's not just the 5x more fuel that that temperature difference might lead you to believe, because metals have a much higher heat capacity, so it takes more energy to get a metal to any given temperature, whereas plastic is light and doesn't need as much energy to get it to the same temperature. If you want to do a natural experiment to demonstrate something you already know about heat capacity, find any plastic surface in your surroundings and touch it. It might feel a little cool. That's because your skin is at around 92°F and the plastic is at room temperature, so maybe 75°F, so your skin is passing its energy to the plastic, which is warming from contact with your skin. Now touch a piece of metal in the room and it feels much cooler, almost cold. Obviously, the metal is also at room temperature, so 75°F, so why does it feel colder? Because it has a higher heat capacity, being made of a denser material, it's taking more energy from your skin when you touch it. This is the same reason that taking metal to any given temperature takes more energy than taking plastic to the same temperature, and on top of that, melting metal requires a temperature 5x higher than plastic.
[These same points about energy of melting apply to any metal, including aluminum, which has a slightly lower melting point than steel: 1220°F, and glass, which doesn't have a melting point technically, but has to be heated to around 2000°F to be molded.]
So now that we have this intuition that it takes much more energy to make metal and glass materials, even by recycling, I think the next objection from a stainless-steel only advocate would be around extraction. Plastic comes from oil extraction. True. Oil extraction has many negative environmental effects. True. These negative externalities must be counted against virgin plastic. True. (This is why Buoy makes its products out of recycled plastic.)
As you must realize, metal production also involves extraction. Ore mining is a dirty business. Strip mining destroys the land. The chemical processes of extracting the metal from ore often leaves toxic lakes in areas where the mining is done.
A levee holding back a toxic lake broke and flooded a nearby town.
Even in a place like the US, where ore processing is handled more carefully, there are environmental costs. And because regulations make extraction more expensive here, producers are likely to go elsewhere. Virtually all of the stainless steel food containers and bottles that would be used to substitute for Buoy products are made in China, which would source iron, magnesium, chromium and nickel from the cheapest provider, which would be more likely to not be taking pains to reduce environmental impacts.
We'll end this installment at this point, where we have explained why plastic has a lower carbon footprint / environmental impact than stainless steel. But the stainless steel advocates would not give up their position based only on carbon. They would be quick to point out that carbon footprint is not the only problem that plastic causes. Microplastics damage marine life and other animals in our environment. True. (This is why Buoy's supply chain is designed to recycle and use plastic that would otherwise become ocean pollution.) We'll start the next installment with a full presentation of the stainless steel optimist position and then do a deep dive into each part of the argument.
© 2023, Buoy, LLC
Reposted December 2025.
