Your guide to steel decarbonisation

Essentially, green steel is the manufacturing of steel without the use of fossil fuels. However, there are several proposed definitions and standards for green steel which makes it difficult to have a shared definition! “Green steel” can refer to low embodied carbon, near zero embodied carbon, net zero embodied carbon, 100 percent recycled content, ethically sourced, or responsible steel.

There has been a notable increase in the number of standards, protocols, initiatives, and government policies focusing on either the producers of steel, the demand side of steel procurement, the finance and funding side or some combination thereof For a great overview of the current “green steel” standards, protocols, initiatives, and policies and their complexities, it's worth checking out Global Efficiency Intelligence’s What is Green Steel? They include:

• Responsible Steel Standards & Certification

• GHG Protocol for Steel

• Climate Bonds Initiative’s Criteria for Climate Bonds for the Steel Industry

• World Steel Association’s Protocols

• ISO 14067:2018 – Carbon Footprint of Products

• ISO 14404 Series – Plant Level CO2 Emissions Intensity From Iron and Steel Production

• American Iron and Steel Institute’s Steel Production Greenhouse Gas Emissions Calculation Methodology Guidelines

The Green Steel Hub does not endorse any definition or standard for “green steel,” but rather helps readers understand the processes and technologies necessary to lower emissions from producing steel.

Essentially, green steel is the manufacturing of steel without the use of fossil fuels. There are a few newer technological processes in steelmaking that use no or lower amounts of fossil fuels. They include a combination of:

• Scrap-based Electric Arc Furnaces (EAF) powered by renewable energy

• Hydrogen Direct Reduced Iron (DRI) in EAF and Smelter-BOF

• BF-BOF + Carbon Capture and Storage (CCUS)

• Direct electrolysis of iron ore (Molten Oxide Electrolysis and Electrowinning)

Electric Arc Furnaces (EAF) are a newer steelmaking technology that do not use coal for heating or making coke. They can be powered by 100% renewable energy, which further lowers emissions from steel production.

EAFs can be “fed” by scrap steel, which means that existing steel can be melted in the EAF and reused in different steel products. In this way, steel is almost 100% recyclable, and using scrap in steelmaking uses less energy that making primary (new) steel. This means the industry needs to improve how it collects end-of-life steel and improve steel recycling to increase circularity in steel production and use.

It is also possible to feed EAFs with direct-reduced iron (DRI) (remember, steel is made from reduced iron and carbon). DRI production turns iron ore into iron using a reducing gas. Using green hydrogen as the gas in the DRI process, as opposed to natural gas, could reduce CO2 emissions to 50 kilograms or less per tonne of steel — a 97% reduction.

DRI can also be retrofitted in the BF-BOF pathway, known as DRI-Smelter-BOF. DRI is produced by green hydrogen, melted down in a smelter, and then added to a traditional BOF to produce steel. For a quick video explanation of this process: https://www.youtube.com/watch?v=eEY0I_ORnDE

Recycled steel can also be used in BF-BOF furnaces, but in lower volumes that EAFs. The current best option for lowering emissions from BF-BOF steelmaking (which uses coal as the main fuel source) is capturing carbon emissions and storing them underground (CCUS). Not exactly carbon friendly!

Finally, a new “electro-chemical” process that is ready for commercial use relies on renewable energy and iron ore to reduce iron through “molten oxide electrolysis.” It’s complicated, but a chemical solution containing iron ore is heated up via renewable energy, which reduces the iron directly into a liquid necessary to make steel. If this sounds fascinating, we invite you to visit Boston Metal, who invented the process: https://www.bostonmetal.com/green-steel-solution/

Green public procurement (GPP) is a policy instrument that governments use to buy goods with a reduced environmental impact throughout their lifecycle relative to similar goods that provide the same function (GEI). GPP adoption is increasing around the world as national governments, sub-national governments, and multilateral entities develop policies to reduce their carbon footprints and create new low-carbon markets.

Steel decarbonisation is the process of reducing and removing net greenhouse gases (GHGs) that are produced in steelmaking by:

• using zero or low-emission energy sources in steelmaking;

• increasing energy efficiency and circularity; and

• by carbon capture use and sequestration (CCUS).

Steel decarbonisation matters due to its huge contribution to climate change – steel is currently estimated to account for 7-9% of global emissions. And these emissions continue to increase. Global Energy Monitor calculations show that steel sector CO2 emissions rose from 3.6 Gt in 2019, to 3.7 Gt in 2020, and 3.8 Gt in 2021. To align with the IEA’s NetZero by 2050 scenario , direct CO2 emissions from the global iron and steel industry need to be lowered to 1.8 Gt CO2 by 2030 and 0.2 Gt CO2 by 2050.

Scrap steel is iron and steel broken down and collected as a by-product of manufacturing, and from products at the end of their uses, like building materials, vehicles, domestic appliances, machines, etc. (More info on steel scrap here). Steel is, in fact, the most recycled material in the world. In 2021, global steel industry used an estimated 680 million tonnes (Mt) of recycled steel to produce 1.95 billion tonnes of crude steel (World Steel Association). As discussed in the “Newer technologies” section , electric arc furnaces (EAFs) that use scrap as a feedstock is a well-established process in steelmaking to lower emissions. It remains more expensive than BF-BOF because of the upfront costs of constructing new EAFs and, potentially, the energy source for the electricity that powers the furnace.