Apologies for the long read, but just to clarify for anyone reading my original post – I am NOT saying that manufactured stainless steel PRODUCTS are dangerous, just the process of extracting and producing the raw materials needed to make it. Even though they contain carcinogenic and toxic materials – the manufactured products themselves are seen as being an inert material and perfectly safe to use and with many benefits.
As for their production, when it comes to facts and figures regarding plastics vs metals, these will vary wildly when you read reports depending on who has written the report and what their agenda/backing is.
One point that is common though is that the component materials mined and smelted for stainless production are conveniently ignored.
There are many reports such as this one:
LIFE CYCLE IMPACTS OF PLASTIC PACKAGING COMPARED TO SUBSTITUTES
that detail the massive impact on increased energy usage needed if we were to switch wholesale from plastic to plastic alternative packaging. In the US alone that would be the equivalent of adding the energy needs of an extra 3.5 million homes every year. Unless that energy was 100% provided by sustainable sources then this just compounds the problem.
When you read about energy consumption of plastic packaging production, the most common one you will see is relating to a bottle of water. These are ALWAYS heavily skewed as the numbers given relate to its full life cycle including oil extraction, material manufacture, bottle manufacture, shipping, filling, labelling, packing, shipping to retailers, disposal etc.
Its far simpler and more transparent if you can simply look at the mathematics involved in the manufacturing of the base materials and how much you get out of them. (these are readily available with a little research) While the energy used to create plastic resins varies depending on the plastic – it ranges from 55 to the worst (polystyrene) at 87.4 GJ/tonne and a CO2 output of 5.1 tonnes per tonne of resin, stainless has a fairly constant output including the core materials and steel production itself:
Iron: 22GJ/tonne
Nickel: 114GJ/tonne
Ferrochrome: 56GJ/tonne
304 stainless: 75GJ/tonne
Total: 267GJ/tonne
For your comparison, the global average family home uses around 100GJ per year increasing to 130GJ in colder climates.
So if we take a high density plastic such as food grade PP used in traditional shakers, that requires 73.4GJ/tonne. The finished bottle component weighs 77g meaning you can get 12,987 bottles from one tonne of material resulting in it having a production energy impact of 0.005GJ per bottle.
If we compare that to the Huel single wall (not insulated) stainless bottle you are approx.135g so 7,407 bottles from one tonne of material and 0.036GJ per bottle which is 7 times the energy needed to make one stainless product over an equivalent capacity HD plastic one.
If you imagine the distribution and delivery logistics of these products are almost double than a plastic one, then that further weakens their position as a good alternative. Typically, the combined energy needed for road freight container transport equates to 191 kilojoules per tonne per kilometre.
It’s also worth considering end of life scenarios – the carbon footprint of one tonne of stainless steel requires around 75GJ energy and 6.6 tonnes of CO2 emissions to recycle whereas plastic needs only 8GJ and 450kg of CO2 emissions
By far the largest gaseous emission in plastic resin production is CO2 due to its main ingredient – oil. Other gases released in smaller amounts are trichloroethane, acetone, methylene chloride, methyl ketone, styrene, sulphur and nitrous oxides.
If you combine the emissions of harmful gases in the production of virgin stainless (including its core components) they are far more varied and larger in amounts – some of the nastier examples would be:
- Carbon Dioxide: 24.8 tonnes / tonne of finished product
- Carbon Monoxide: 0.239 tonnes / tonne of finished product
- Methane: 0.66 tonnes / tonne of finished product
- NOx: 2.62 tonnes / tonne of finished product
- NMVOC: 0.34 tonnes / tonne of finished product
(benzene, ethanol, formaldehyde, cyclohexane, 1,1,1-trichloroethane, acetone etc.) - Sulphur Dioxide: 2.2 tonnes / tonne of finished product
Many advocates will also tell you that stainless doesn’t have any run off pollutants entering the water system and food chain – while technically this is true only in the context of the finished stainless production, it most certainly is not true of the production of its many core components such as chromium and nickel. These are major polluters with highly toxic and carcinogenic by-products contaminating the water and land around their production as well as presenting serious health hazards to the people fabricating it.