Steel is the foundational material of modern infrastructure, used everywhere from skyscrapers to automobiles. The process of making steel is a massive source of global carbon dioxide emissions, largely because it relies on coal. While traditional steel production is deeply rooted in this fossil fuel, the answer to whether steel can be made without coal is a definitive yes. The transition, however, presents significant technological and economic hurdles, making the search for viable alternatives a major global focus.
The Essential Role of Coal in Conventional Steelmaking
In conventional steelmaking, specifically the Blast Furnace–Basic Oxygen Furnace (BF-BOF) route, coal serves two primary functions. First, it provides intense heat. Metallurgical coal is converted into coke, a porous, high-carbon material, which is combusted to generate the high temperatures necessary for smelting iron ore and other raw materials.
Second, coal acts as a reducing agent. Iron ore is iron oxide, and oxygen must be chemically stripped away to yield pure iron, a process called reduction. When coke burns, it produces carbon monoxide gas. This gas reacts with the iron oxide, removing the oxygen atoms. This chemical reaction releases a large amount of carbon dioxide, which is why conventional steelmaking accounts for a substantial percentage of global industrial emissions.
Existing Methods That Reduce Coal Dependency
Established technologies reduce the reliance on metallurgical coal, though they do not eliminate all fossil fuels. The Electric Arc Furnace (EAF) method primarily makes steel by melting recycled scrap steel using high-power electric arcs. Since EAFs bypass the step of reducing iron ore, they avoid the need for coke and the associated carbon emissions.
EAFs account for a significant portion of global steel production, but their expansion is limited by the availability of scrap steel. Scrap is a finite resource and cannot meet the total global demand for new steel. This forces the industry to rely on iron ore reduction for primary steel production, making coal-free methods for processing ore necessary.
Another commercially mature technology is Direct Reduced Iron (DRI) production, which uses natural gas instead of coke as the reducing agent. Methane (natural gas) is reformed to create a reducing gas rich in hydrogen and carbon monoxide. This gas converts solid iron ore into metallic iron, or “sponge iron,” at temperatures below the melting point.
Natural gas-based DRI significantly lowers carbon emissions compared to the BF-BOF route, sometimes by over 50%. However, the reducing gas still contains carbon monoxide, meaning the process releases carbon dioxide and is not a zero-carbon solution. The DRI product is typically melted in an EAF to produce finished steel, creating a more efficient, lower-carbon product.
Zero-Carbon Pathways for Steel Production
The push toward truly coal-free and zero-carbon steel production centers on two emerging technologies that eliminate carbon-based reducing agents. The most advanced is Hydrogen Direct Reduction (H-DRI), which modifies existing DRI infrastructure to use pure hydrogen gas instead of natural gas. In the H-DRI process, hydrogen reacts with the oxygen in the iron ore at high temperatures.
The chemical reaction is significant because the only byproduct is water vapor, completely eliminating carbon dioxide emissions from the process. For this to be a zero-carbon pathway, the hydrogen must be “green hydrogen,” produced via the electrolysis of water powered by renewable electricity. H-DRI is seen as the primary near-term pathway for decarbonizing primary steel production, with several large-scale pilot projects underway globally.
A second, more experimental zero-carbon method is iron ore electrolysis, also known as Molten Oxide Electrolysis (MOE). This process is similar to aluminum smelting, where a large electrical current is passed directly through iron ore dissolved in a molten electrolyte. The electricity acts as the reducing agent, separating the iron from the oxygen.
The only byproduct of MOE is pure oxygen gas, entirely bypassing the need for any carbon-based fuel or reducing agent. The process requires immense amounts of clean electricity but operates at a lower temperature than a blast furnace and can produce liquid iron directly. While still at the laboratory or small pilot scale, MOE represents a potential long-term, single-step path to coal-free steel, provided the challenges of scaling the technology and developing robust inert anode materials are solved.
Scaling Up: Economic and Infrastructure Challenges
While the technology exists to produce steel without coal, the transition requires overcoming substantial economic and logistical hurdles. New coal-free production methods, particularly those involving green hydrogen, demand a massive increase in clean electricity generation. The energy required for green hydrogen production and the subsequent operation of Electric Arc Furnaces is estimated to be three to four times higher than the traditional BF-BOF route.
The current cost of green hydrogen is a significant barrier, often priced at double the cost of conventional fossil-fuel-based hydrogen. Although costs are expected to decrease as technology matures and economies of scale take effect, the “green premium” makes this steel economically uncompetitive without carbon pricing or subsidies.
The required infrastructure overhaul is immense, demanding the construction of new hydrogen production facilities, storage, and distribution pipelines. Existing blast furnaces, which are multi-billion dollar assets designed to operate for decades, must be completely replaced or retrofitted. This massive capital investment, combined with the need to ensure a reliable supply of renewable energy and hydrogen, means the shift from coal-based steel will be a gradual, decades-long undertaking.