SSAB has sponsored this post.
As a process, steelmaking is old enough that its origins are lost to history, with early forms dating back to the classical era in Europe, Asia and the Middle East. Modern steelmaking is essential to our way of life: from our vehicles to our homes, steel products can be found almost anywhere.
Unfortunately, this ubiquity comes at a price. According to a 2021 estimate, the global steel industry accounts for approximately 7 percent of total greenhouse gas emissions. The reasons for this are technical—in the process of steelmaking itself—as well as economical, in the sense of how that process is powered.
SSAB, one of the world’s most advanced steel companies, is tackling this issue on both fronts. To understand the challenges involved in reducing carbon emissions, it helps to start with a look at the technologies behind modern steelmaking.
Modern Steelmaking Processes
Today, steel is made in three steps: first, iron ore is converted to iron (primary steelmaking), other elements are then either added or removed (secondary steelmaking) and finally the resulting steel or steel alloy is cast and rolled into plates, sheets or coils (tertiary steelmaking). The majority of carbon emissions originate with the blast furnace process in primary steelmaking when coal—specifically coke—is used to remove oxygen from the iron ore. The carbon in the coal bonds with oxygen in the iron ore to create carbon dioxide.
“This means that for every ton of iron you make, you get at least 1.5 tons of CO2 as part of the deal,” explains Thomas Hoernfeldt, vice president, Sustainable Business at SSAB. “That’s a chemical fact, so you can’t really do much about it to reduce emissions. We at SSAB are actually quite close to the lower limit with blast furnace technology today.”
An alternative approach is to use an electric arc furnace (EAF), in which steel scrap is melted by using an electric arc. EAF steelmaking generates considerably less carbon emissions directly compared to using a blast furnace, but it can still account for greenhouse gas emissions indirectly if the source of the electricity is fossil fuels, such as coal and natural gas.
“So, if we want to decarbonize and get rid of our CO2 emissions, we need to do something differently,” says Hoernfeldt. “We needed a new technology to make steel from ore and, after exploring various options, we realized that what we should do in the future is expose the iron ore to hydrogen, not to carbon and coke.”
This is the basis of SSAB’s HYBRIT technology (Hydrogen Breakthrough Ironmaking Technology). By replacing the coke and using a direct reduction process, the oxygen in the iron ore bonds with hydrogen rather than carbon, resulting in water, rather than carbon dioxide. “We use electricity from the virtually CO2-free power grids in Sweden and Finland for electrolysis to remove the oxygen from water to make hydrogen,” explains Hoernfeldt, “and then we replace that with oxygen atoms from the iron. We end up with some oxygen left over, but we can use that in our processes downstream.”
Unlike a traditional blast furnace, the product of the HYBRIT process is not liquid iron but solid lumps called sponge iron. SSAB utilizes an EAF to convert that into liquid form for secondary and tertiary processing. “From then on, all the downstream processes—the alloying, the casting, the heating and rolling to the correct dimensions—they’re all going to be the same in the future as they are today,” says Hoernfeldt. “We just need to make sure we’re using fossil-free electricity and fossil-free fuels, such as biogas [known as renewable natural gas (RNG) in the US], in these processes.”
It's worth noting that HYBRIT does not result in hydrogen brittleness, a potential drawback of hydrogen-based steelmaking. “There is absolutely no reason for that because we’re using hydrogen in the ironmaking part of the process,” explains Hoernfeldt, “And in the unlikely event that there would be any hydrogen somehow hiding between the iron atoms, that will not survive the electric arc furnace.”
Shrinking Steel’s Carbon Footprint
The size of steel’s carbon footprint is due to more than just the emissions that result from the steelmaking process itself. According to IEA, the iron and steel sector consumed more than 800 million tonnes of oil equivalent in 2019, or roughly 9,800 MWh of electricity. Given that renewables make up less than a third of global electricity generation, that leaves a lot of room for reducing the indirect emissions from steelmaking.
“It’s surprisingly straightforward,” says Hoernfeldt, “It’s actually only a matter of replacing the fuel and the electricity, but nobody has done this in the market mainly because it’s hard to find fossil-free electricity.”
In SSAB’s Iowa facility, for example, the EAF process is powered by wind farms in the Midwest, supplemented with biogas (aka RNG). The company is also using ships powered by biodiesel to move steel and semifinished steel products across the Atlantic, from the U.S. to Sweden and Finland, where renewable electricity is more widely available.
“To be perfectly frank: the steel doesn’t care where the electricity comes from,” says Hoernfeldt, “It’s just a procurement matter, and the same goes for the biogas.” And since only the primary steelmaking is changed when using hydrogen, SSAB can confidently claim that its zero-emission steels have the same performance as its traditional steels despite differences in pedigree.
The knock-on effect of reducing steelmaking’s carbon footprint is that the industries which use fossil-free steel will see their own footprints shrink as well. In the automotive industry, for example, aside from tailpipe emissions—a source that is already in significant decline—materials are the leading contributor to emissions from passenger vehicles.
“Even though steel makes up a large portion of the car, the extra cost for using fossil-free steel is almost equivalent to ordering an extra USB outlet in the backseat,” says Hoernfeldt, “It’s really not much compared to all the other stuff that goes into it.”
The same holds for the construction industry: With the move toward low- and zero-energy buildings, the major contributors to their greenhouse gas emissions are the materials that go into them. Steel is everywhere in construction. Replacing the traditional steel with zero-emission steel in window frames, roofing, facades, ventilation systems and more, can reduce the environmental impact of those buildings even further.
The Future of Steelmaking
SSAB currently has two zero-emission steels in this space: SSAB Zero, which is produced from scrap using fossil-free electricity and biogas, and SSAB Fossil-free steel, which is produced from iron ore using the company’s HYBRIT technology. Hoernfeldt says the company is aiming for 40,000 tonnes of SSAB Zero this year, ramping up to 100,000 tonnes over the next two to three years.
The iron for SSAB’s fossil-free steel is currently produced at the company’s pilot plant in Sweden. The next step is a demonstration plant, with a capacity of 1.3 million tonnes by 2026. By 2030, SSAB expects that capacity to more than double, up to 2.7 million tonnes.
“That would be roughly half of our production capacity in Sweden and Finland,” explains Hoernfeldt, “which is about 5 million tonnes.” By 2030, SSAB will shut down its remaining blast furnaces in these two countries, meaning all the steel produced there will be virtually emission-free in less than a decade. “This is a very fast transition,” admits Hoernfeldt, “especially when blast furnace technology has been around for more than 800 years!”
For more information about SSAB Fossil-free steel and SSAB Zero, visit the SSAB website.