How can steel be made without coal?

Why steel matters

Steel is mainly iron with a small, controlled amount of carbon. It is used in buildings, vehicles and machinery. Making it produces carbon dioxide, and cutting those emissions is a current challenge. In its Breakthrough Agenda Report 2025, published on 30 October 2025, the International Energy Agency (IEA) reported that total CO2 emissions from steel were largely unchanged from recent years, while the direct CO2 emissions intensity of steelmaking had seen an uptick since 2021 (IEA, IEA report page).

How conventional steelmaking works

Molten iron from a blast furnace is called pig iron or hot metal. A typical hot-metal charge for a basic oxygen furnace contains about 4% carbon (Wikipedia). Steelmaking removes most of that carbon and other impurities.

Henry Bessemer was granted British patent number 356, dated 12 February 1856, for his steelmaking process. In his converter, air was forced into the furnace from the bottom, below the molten pig iron (EBSCO). The impurities are removed by oxidation, and this oxidation raises the temperature of the iron and keeps it molten (National Iron & Steel Heritage Museum).

Today's main route is the basic oxygen furnace. A lance blows 99% pure oxygen, supplied at a pressure of 700 to 1,000 kilopascals, over the hot metal (Wikipedia). The earlier open-hearth furnace used the Siemens regenerative furnace design, and in 1865 Pierre-Émile Martin took out a licence from Siemens and applied it to steelmaking (Wikipedia).

The electric arc furnace takes a different approach. It allows steel to be made from a feedstock of 100% scrap metal (Wikipedia). The charge is heated both by current passing through it and by the radiant energy from the arc (Wikipedia).

In the main route today, molten pig iron from a blast furnace is refined into steel in a basic oxygen furnace (Wikipedia). The IEA reports that hydrogen direct reduced iron fed to electric arc furnaces is "emerging as a preferred low-emissions option in certain regions" (IEA).

What has been demonstrated

These are the parts the sources show as established. Robert Durrer's experimental converter produced its first steel on 3 April 1948 (Wikipedia). The first oxygen converters went into operation at Linz in November 1952 and at Donawitz in May 1953 (Wikipedia). Most open-hearth furnaces were shut down by the early 1990s, and in the United States they had stopped by 1992 (Wikipedia).

In its 2025 report, the IEA said blast furnace and basic oxygen routes made up about 70% of global steel production (IEA).

The sources reviewed give no measured output or emissions figures for any low-carbon pilot or plant, so this article gives none.

What is only reported

These are plans and estimates, not measured results. All figures below come from the IEA's Breakthrough Agenda Report 2025, published in October 2025, and may since have changed.

The IEA estimated that early commercial plants using 100% hydrogen blends cost 50% to 140% more than blast furnace and basic oxygen plants, varying by region, and that this was slowing deployment (IEA).

The IEA said near-zero emissions capable steel capacity was just over 80 Mt, largely the same as in 2024. Of this, 25 Mt had plans to operate as near-zero emissions by 2030 but came from early-stage projects; the rest planned to run on natural gas at first, with unclear timelines for moving to near-zero emissions (IEA). It also reported that capacity for near-zero emissions iron by 2030 remained at about 10 Mt, unchanged from 2024 (IEA).

What is speculative

The sources reviewed give no year by which blast furnaces would be fully replaced, so this article gives none. Several directions are possible. One is electric arc furnaces, fed mainly with scrap and powered by low-carbon electricity, taking on more of the work that blast furnace and basic oxygen routes do now. Another is hydrogen-based iron supplying electric arc furnaces, if its cost premium falls. Neither is shown at scale in the sources.

Limits and open problems

The IEA's estimate of a 50% to 140% cost premium for early plants using hydrogen blends is a clear cost constraint (IEA).

Electricity is a second constraint. An electric arc furnace only lowers emissions if its power is low-carbon, and the sources do not quantify how much that matters in practice.

Electric arc furnaces do not remove carbon inputs entirely. During a heat, carbon in the form of coke or coal is injected into the slag layer (Wikipedia).

Scrap availability is an open question. The electric arc furnace can run on scrap alone, but the sources do not say how much scrap is available to meet demand.

Product quality is not covered by the sources reviewed, so this article cannot say whether scrap-based or hydrogen-based steel meets every specification.

The IEA noted that direct CO2 intensity had seen an uptick since 2021 (IEA). The sources reviewed do not explain the cause.

What to watch next

• Whether the IEA's figure for near-zero emissions iron capacity by 2030, about 10 Mt in its 2025 report, rises.
• Whether the 50% to 140% cost premium for hydrogen-based plants narrows.
• Whether the rise in direct CO2 intensity since 2021 reverses.
• Whether the 25 Mt of planned near-zero capacity moves from early-stage projects into operating plants.