Stainless steel sustainability

Online Editor

Camilla Kaplin offers five ways to assess the sustainability of stainless steel

Global sustainability targets are changing the rules as end customers are embracing carbon footprint as a deciding factor during procurement. This may initially seem like a complex task as it is tricky to compare suppliers directly because their reporting style varies. That’s why buyers need to be careful and ask the right questions to identify whether there are any hidden environmental costs.

The other aspect of carbon footprint reporting is that OEMs rely on accurate and reliable data from their own supply chain to confidently calculate the carbon footprint of their products.

To help navigate this landscape, we have highlighted five key areas to give buyers the information they need.

Request carbon footprint data according to a recognised standard

Suppliers of materials such as stainless steel should be able to provide carbon footprint data in a format that enables straightforward comparison. An ideal approach is the Environmental Product Declaration (EPD) under the ISO 14040 standard, which requires data to be verified by an independent third party.

The standard defines carbon footprint across three scopes. Suppliers should provide data for all three to avoid any hidden carbon dioxide figures.

Scope 1 covers the supplier’s direct CO2 emissions – for stainless steel, this could be from the fuel used in heating furnaces. Scope 2 accounts for indirect emissions, for example from electricity generation for powering electric arc furnaces and motors in the rolling mills. Scope 3 covers emissions embedded in the raw materials arriving at your supplier’s factory gate. These typically make up the bulk of emissions for stainless steel and cover mining, ore processing, and scrap recycling.

The combined figure of all three scopes is the one to consider. This is because individual scopes may vary widely between suppliers, depending on their production processes and sourcing strategies.

For example, some stainless steel producers make their own ferrochrome as a raw material for alloying, and therefore would account for energy to process it under scopes 1 and 2. In contrast, other suppliers buy in ferrochrome and would need to report it under scope 3. This requires accurate and verified data from the supply chain.

Compare the level of recycled content in the finished product

The percentage of recycled content used in the manufacture of stainless steel is another way to evaluate carbon footprint. Recycling stainless steel consumes less energy than processing virgin ore, which translates to fewer emissions. This has been studied by Germany’s Fraunhofer Institute, which found that every tonne of austenitic scrap used in stainless steel production saves 4.3 tonnes of CO2 emissions.

Therefore, the recycled content is a simple way to get a good feel for carbon footprint. It varies widely – a recent report by Yale University found that the global average of recycled content is only 44%. However, at Outokumpu, the input of recycled material is 90%.

Determine your supplier's local environmental impacts

The processes inside a steel mill or any industrial facility produce emissions such as dust and discharge to water. These could impact the quality of water, air, land, and quality of life for communities living close to the plant. It’s therefore important to ask how suppliers limit their local impact.

Treating process water and capturing dust before it escapes into the air protects the environment and preserves biodiversity. Furthermore, it also enables recycling and reuse of valuable raw materials.

This sort of information should be available in a supplier’s annual sustainability report, along with information about EPDs. Outokumpu goes the extra mile in this regard, as it follows the Global Reporting Initiative (GRI) so that readers can be certain that the data has been assured by an auditor.

Select the right grade

To protect the environment, it’s essential to design products to last. Today, many engineers base decision-making and procurement on life cycle costing (LCC). Apart from covering the initial cost, LCC also includes costs related to the operation, maintenance, and end-of-life disposal.

The right grade of stainless steel can extend the useful life of a product or infrastructure by decades. A good example is the Tokyo Water Board, which adopted stainless steel pipes for its water network. Instead of a 20-year lifespan like other modern materials, the pipes are designed to last 100 years. These pipes have drastically reduced leakage and street works so that Tokyo’s population can thrive without disruption.

Another example of extending the service life is the Stonecutter´s Bridge in Hong Kong, China, where Outokumpu duplex steel was used at the top of the tower to ensure a 120-year maintenance free life for the structure that supports the bridge’s suspension cables.

Therefore, obtaining expert advice before specifying a material makes good environmental and financial sense.

Check third-party credentials

Another effective way to compare suppliers is to check where they are listed on sustainability indexes and ratings. This will show whether they meet the high standards set by international bodies and industry organisations. Examples include listings in the S&P Sustainability Yearbook and EcoVadis. Leading companies have also committed to initiatives such as the UN Global Compact and the Science Based Targets initiative.

Although it may seem daunting to evaluate suppliers on both financial and sustainability grounds, it can be straightforward by following these five guidelines.

Camilla Kaplin is senior manager – Environment at Outokumpu

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