HMN 2025: How Retrofitting plants offers big cuts at moderate cost

A powerful new database and economic model that identifies the most cost-effective strategies to reduce the carbon emissions from the world’s iron and steel processing plants has been developed by researchers from UCL.

The study, published in Nature, examined the carbon reduction potential and economic implications of upgrading every iron and steel processing plant worldwide.

Researchers analyzed nearly 4,900 plants worldwide and found that a “medium pathway” approach—retrofitting plants as they age—could cut 22.4 billion tons of carbon dioxide (CO?) globally between 2020 and 2050, at an average cost of about $24.7 per ton of CO?, or $543.4 billion total. This strategy balances cost and impact, and gives companies the most flexibility, while delivering significant emissions reductions.

By contrast, the team’s “late pathway”—delaying upgrades until the latest possible retrofit cycle date—would cost about $351 billion over that period but only reduce CO? emissions by around 13.5 billion tons.

On the flip side, if countries wanted to prioritize rapid decarbonization, they calculated their “early pathway” could reduce emissions by a total of 52.7 billion tons during that time, but cost more than $2.8 trillion.

Collectively, the iron and steel industry accounts for 7% of global carbon emissions or about 2.7 billion tons annually and is expected to increase in the coming decades because of continued urbanization and industrialization. However, reducing the industry’s carbon emissions is notoriously difficult, due to its reliance on fossil fuels and long-lived infrastructure, locking in old, emission-heavy technologies.

New, cleaner technologies and techniques are emerging, like scrap recycling, carbon capture, hydrogen, bioenergy and direct electrorefining, and all hold promise to significantly reduce emissions of the industry in different ways. However, there’s no one-size-fits-all approach; each tech option depends on its technological readiness, economic viability, and compatibility with existing plants.

Lead author Professor Jing Meng (UCL Bartlett School of Sustainable Construction) said, “The iron and steel industry is a major greenhouse gas emitter but hard to abate. By examining the most promising technologies and their projected costs, we’ve been able to chart a clear, data-driven path forward for the industry to ultimately achieve Net Zero carbon emissions cost-effectively.”

Co-author, Professor Dabo Guan (UCL Bartlett School of Sustainable Construction) said, “There are many different processing plants, emerging technologies and potential emissions reduction strategies that this becomes an incredibly complicated landscape very quickly. Not all new technologies will work at all existing plants; different strategies will work best in different regions and plant types. We’ve been able to capture this diversity to reveal the most realistic and affordable pathways for global steel decarbonization.”

Additionally, the researchers emphasized that most of these clean technology upgrades will only happen if governments around the world implement strong requirements and financial support encouraging companies to decarbonize; otherwise, only a small number of steel plants worldwide would cut emissions substantially.

Database and model

To build this plant-level model—called NZP-steel—the researchers compiled detailed data on nearly 4,900 iron and steel plants worldwide. Of these, 1,967 facilities account for 98% of global steel production and up to 90% of the sector’s CO? emissions. Each facility’s size, age, location, production output, and technology type were incorporated to evaluate current operations and potential upgrades.

The NZP-steel model integrates this database with dynamic cost forecasts for emerging technologies, generating actionable, least-cost plant-specific strategies for policymakers and industry leaders to achieve net-zero steel production.

The content is provided for information purposes only.