Hydrogen Steel

Nearly all ore-based steel today begins in a blast furnace, where coke made from coal strips the oxygen from iron ore and leaves CO2. Hydrogen steel replaces that step. In a direct reduction shaft furnace, hydrogen reacts with the ore to produce solid direct reduced iron (DRI) and water vapor; the DRI is then melted in an electric arc furnace (EAF), cast, and rolled like any other steel. The grades do not change: ASTM A992, A36, A572, and A500 are defined by chemistry and mechanical properties, and a section rolled from hydrogen-reduced iron has to meet the same specification as one rolled from scrap.

The difference is in the footprint. worldsteel’s latest route averages put the blast furnace route at 2.34 tonnes of CO2 per tonne of crude steel, natural-gas direct reduction with an EAF at 1.47, and scrap-based EAF at 0.69 (worldsteel, Sustainability Indicators 2025); SSAB’s HYBRIT process targets below 0.05 (SSAB), and the IEA defines near-zero-emission steel as 50 to 400 kg CO2e per tonne depending on scrap content (IEA, 2022). The furnace exists: the MIDREX H2 shaft furnace is designed to run on 100 percent hydrogen, and the first commercial plant of its kind is under construction in Boden, Sweden (Midrex). What does not yet exist at scale is cheap low-carbon hydrogen, which is why the source of the hydrogen matters as much as the furnace, and why we put it in the name.

Hydrogen itself is colorless. The colors are industry shorthand for how the hydrogen was obtained (National Grid), and they are a label, not a measurement: two “blue” plants can have very different emissions depending on how much CO2 they capture, which is why the IEA calls the color terms impractical as a basis for contracts (IEA, April 2023). Our rule follows: the color tells you the source, the environmental product declaration (EPD) tells you the number, and no name goes on a steel package without the number behind it. We do not use grey, brown, black, or yellow as names. Other hydrogen sources can join the family as they are proven, under the same rule.

Steel made from iron reduced with green hydrogen: hydrogen produced by electrolysis of water using renewable electricity, with the DRI melted in an EAF that also runs on low-carbon power. It is the tier with the lowest footprint and the one most people mean by “green steel” or “fossil-free steel.” Sweden is furthest along: Stegra’s Boden plant is funded and under construction with no first-steel date published (Canary Media, April 2026), and no U.S. plant exists, so early volumes will reach U.S. projects from European mills, often as environmental attribute certificates tied to a specific plant. Green Hydrogen Steel™ is a registered trademark of Yamaguchi Heavy Industries Ltd. in Japan (Registration No. 7088848) and is used as a trademark in the United States. Read the guide: Hydrogen Steel Explained.

Steel made from iron reduced with blue hydrogen: hydrogen produced from natural gas by reforming, with the CO2 captured and stored underground. The furnace and the chemistry are the same as the green tier; the footprint depends on the capture rate and on upstream methane, so it lands between natural-gas DRI and green. Its advantage is practical: it can be built where natural gas, pipelines, and CO2 storage already exist, and Texas, with one third of U.S. hydrogen output and more than 1,000 miles of hydrogen pipelines, names direct reduction of iron as an industrial use it wants to attract (Texas Railroad Commission, December 2024). Blue Hydrogen Steel™ is a registered trademark of Yamaguchi Heavy Industries Ltd. in Japan (Registration No. 7088849) and is used as a trademark in the United States. Read the guide: Hydrogen Steel Explained.

“Blue” appears in two of our names, with two roles. Blue Hydrogen Steel™ is the tier described here, named for the hydrogen color code: hydrogen made from natural gas with the CO2 captured and stored. Blue Carbon Steel™ is the concept and the measurement procedure behind the Hydrogen Steel program as a whole, and it applies to all five tiers. Blued steel and Blue Steel are unrelated: they describe a surface oxide finish and a knife steel. A specification should spell out which one it means.

Steel made from iron reduced with pink hydrogen: hydrogen produced by electrolysis powered by nuclear electricity, including variants that use reactor heat for high-temperature electrolysis or thermochemical water splitting (sometimes called purple or red). The IEA puts hydrogen from nuclear-powered electrolysis at 0.1 to 0.3 kg of CO2e per kg, against about 11 kg for unabated natural gas (IEA, April 2023), so this tier is comparable to green. The United States has one small operating unit, at Constellation’s Nine Mile Point plant in New York (Constellation, March 2023), and Japan aims to make hydrogen with heat from its HTTR test reactor by 2030 (JAEA, March 2025). Pink Hydrogen Steel™ is a trademark of Yamaguchi Heavy Industries Ltd.; a trademark application is being prepared.

Steel made from iron reduced with turquoise hydrogen: hydrogen produced by methane pyrolysis, in which natural gas or biomethane is split at high temperature into hydrogen and solid carbon. No CO2 is formed at the plant; the carbon comes out as carbon black or graphite that can be sold or stored as a solid, and the footprint depends on the energy that drives the pyrolysis and on upstream methane (University of Victoria IESVic, August 2025). No steelmaker yet reduces iron this way, but a U.S. pilot direct reduction furnace fed by pyrolysis hydrogen has Department of Energy funding with U.S. Steel (Steel Times International, July 2024), and the hydrogen itself is being made in Texas, at a pilot in San Antonio and a planned BASF and ExxonMobil demonstration plant at Baytown (BASF, November 2025). Turquoise Hydrogen Steel™ is a trademark of Yamaguchi Heavy Industries Ltd.; a trademark application is being prepared.

Steel made from iron reduced with white hydrogen, also called natural or geologic hydrogen: hydrogen that forms underground when water reacts with iron-rich rock or is split by natural radiation, and accumulates in the subsurface (USGS). It is extracted, not manufactured, so its footprint comes from drilling, from separating the hydrogen from nitrogen, methane, and helium, and from leakage. The U.S. Geological Survey estimates the subsurface may hold on the order of 5.6 trillion tonnes, most of it impractical to recover (USGS, Science Advances, December 2024); the only commercial production today is a small field in Mali, about 5 tonnes a year, and the IEA does not expect natural hydrogen to contribute meaningfully before 2030 (IEA, Global Hydrogen Review 2025). Exploration is under way in Kansas, Iowa, France, and Australia, with iron ore miner Fortescue holding 39.8 percent of the Kansas explorer HyTerra (HyTerra, September 2024) and Osaka Gas and Mitsubishi Heavy Industries Americas among the investors in Koloma (Koloma, October 2024). No steelmaker uses it yet. White Hydrogen Steel™ is a trademark of Yamaguchi Heavy Industries Ltd.; a trademark application is being prepared. It is unrelated to the Japanese knife steel known as White Steel.