Over the past 140 years, structural steel has become a fundamental material for construction. Acceptance was slow until the turn of the last century, with wood and masonry being preferred. Tragic events like the 1885 Chicago fire and the 1906 San Francisco earthquake resulted in steel being viewed in a favoured light by engineers and architects around the world.
Today, the steel industry is one of the top three carbon emitters, responsible for about eight per cent of global emissions. In fact, current processes produce 1.8 times the amount of CO2 (in tons) than the steel itself. That makes it a focus of CO2 reduction initiatives.
Governments have made promises to reduce carbon emissions as part of the Paris Agreement. In addition, a 2021 SteelLens commentary by McKinsey says the steel industry faces specific marketplace challenges. It summarizes these as: changing customer requirements and growing demand for carbon-friendly steel products; tighter carbon emission regulations; and growing investor and public interest in sustainability.
Steel producers are considering alternate ways to power their furnaces in order to create the high temperatures required for production. Hydrogen power is one possible solution.
“Hydrogen-based (H2) steel production can be implemented either in forthcoming (greenfield) sites or existing (brownfield) facilities,” writes McKinsey.
The problems with hydrogen are time and expense. Existing facilities must either be retrofitted or entire new facilities built from scratch.
The energy and costs associated with the production of “green” hydrogen itself is also an issue, another McKinsey reports says.
“Producing two million tons of hydrogen-based steel requires a green hydrogen amount of 144,000 tons. A capacity of 900 MW, or nine of the world’s largest planned electrolysis plants producing 100 MW, is needed to produce this amount of green hydrogen. Furthermore, green hydrogen prices, largely driven by renewable electricity, must decrease simultaneously to make the economics work, linking hydrogen supply security to the importance of renewable power supply.”
The steel industry has other ways to address CO2 emissions, such as improved efficiencies of blast furnaces, and carbon capture and storage. Switching to alternate power sources like electric arc furnaces, biomass reducing agents, natural gas or renewable power are others. Here again, energy source transitions like these take time, not to mention considerable financial cost.
This is why news out of the University of Birmingham in the U.K. is particularly exciting.
Prof. Yulong Ding and Dr. Harriet Kildahl from the University of Birmingham’s School of Chemical Engineering have announced the development of a “closed loop” carbon recycling system that could radically reduce carbon dioxide emissions from the steelmaking industry in existing blast furnaces.
That’s important because 70 per cent of the world’s steel today is produced using blast furnaces which produce iron from iron ore, and basic oxygen furnaces which turn that iron into steel. Ding and Kildahl’s process could potentially replace 90 per cent of the coke typically used in those furnaces and produce oxygen as a byproduct.
“Our technology aims to convert this carbon dioxide into useful carbon monoxide that can be reused in the iron ore reaction,” said Kildahl. “This is done using a thermo chemical cycle, which is essentially performing chemical reactions through a change in temperature. In this way, the environmentally harmful carbon dioxide is converted into a useful part of the reaction, forming an almost perfect closed carbon loop. Carbon emissions from furnace steel could be reduced by up to 88 per cent.”
Rather than the years and billions of dollars needed to retrofit or build new steel plants, this new system could be retrofitted directly to existing blast furnaces, resulting in lower costs and near-immediate C02 reductions. That would save jobs and reduce the risk of stranded assets.
University of Birmingham Enterprise has filed a patent application covering the system and its use in metal production. It’s currently looking for long-term partners to participate in pilot studies and opportunities to deliver this technology to existing infrastructure, and to collaborate on development research.
John Bleasby is a Coldwater, Ont.-based freelance writer. Send comments and Inside Innovation column ideas to firstname.lastname@example.org.