So looking into carbon footprint a bit more, as the topic was about Plastic vs Metal - I’ve tried to find some comparative figures about plastic, stainless steel, and credit card manufacturing in general.
PVC / Credit Card
- 20g of CO2 to manufacture a typical 5g credit card (or, 4kg CO2 / 1kg of credit card) - Source
- Credit Cards are most commonly made from PVCA/PVC type plastics, which seem to have a published carbon footprint of 1.9kg CO2/ kg (Source)
- So approx 2.1kg CO2 is attributed to the rest of the process of making a card, that isn’t just the plastic component. (or about 10g CO2 per card).
Stainless Steel Cards
- There’s a lot of variation in Stainless Steel, depending on mining of the core components, and how much scrap steel is used, but…
- A recent report looking into all aspects of Stainless Steel production suggests a total CO2 footprint of 2.90kg CO2 / kg Stainless Steel (Source).
- The metal cards being used in the UK at the mo seem to be 18g each, which gives a carbon figure of 52g CO2 / 18g card, just for the steel.
- Plus 10g / card for the “non material” bits of making a card (assuming this is the same CO2 footprint for metal and plastic, which it is not likely to be).
- And you get a total of 62g CO2 per 18g Metal Card.
So in summary, assuming a similar carbon footprint for making the credit card - a metal card would have at least 3x the carbon footprint of a Plastic Card, so you’d need to be able to use it for 3x as long.
But that is running on a huge number of assumptions and average published data - and likely the biggest incorrect assumption is the carbon footprint of a metal card making process - which given involves laser engraving, is probably higher.
Also not considering disposal here - it’s likely harder to securely dispose of a metal card than it is plastic, but incinerating a plastic card, one source I read, suggested this releases another 5g CO2 into the atmosphere.
(Which is CO2 per 1000 notes, over a 10 year lifecycle).