[ TECHNOLOGY ]
Electric arc furnaces reduce scope 1 and scope 2 CO 2 emissions , thereby significantly reducing the CO 2 intensity of steelmaking , in addition to introducing an element of circularity through scrap re-processing .
hydro schemes . They can be fed with recycled scrap steel which is less energy- and CO 2
-intensive than making fresh steel in a blast furnace . Electr ic arc furnaces therefore reduce scope 1 and scope 2 CO 2 emissions , thereby significantly reducing the CO 2 intensity of steelmaking , in addition to introducing an element of circularity through scrap re-processing .
The use of green hydrogen for the Direct Reduction of Iron ( DRI ) is an indirect method of electrification . Traditional blast furnaces use coal or coke to rip oxygen out of the iron ore through chemical reduction . An alternative to the use of solid coal or coke is to use natural gas or hydrogen as the reducing agent , as is done in MIDREX ® plants .
Green hydrogen is produced from the electrolysis of water using renewable electrical power . CO 2 emissions are avoided through the electrification of the reducing agent production . For the iron maker , it is an indirect form of electrification .
Germany ’ s thyssenkrupp will implement DRI at their Duisburg facility . Green hydrogen is proposed to be produced locally using wind power from a power purchase agreement . The green electrons will be transported to an electrolyzer scheme through the German power grid .
Biocarbon and biogenic
CO 2
Biocarbon , produced from gasification or pyrolysis of wood and other biomass is also receiving attention as a substitute for coal or coke . Pulverized coal injection ( PCI ) can be used in some blast furnaces for iron ore reduction . Others rely on coke derived from coal for the same purpose .
Switching to biocarbon does not reduce the amount of CO 2 that is produced during the conversion of the iron oxide ore to iron , but since the trees removed CO 2 from the atmosphere during their growth , the biogenic CO 2 produced from biocarbon is regarded as carbon-neutral . It also avoids the use of fossil fuels .
ArcelorMittal Dofasco in Canada is proposing to pilot such a process and has signed a Memorandum of Understanding under which they will purchase biocarbon produced at CHAR ’ s cutting-edge facility in Thorold , Ontario starting in 2023 . CHAR ’ s proprietary high-temperature pyrolysis cracking process transforms wood waste into renewable natural gas and biocarbon .
The biggest question for green steel is how to decarbonise
Perhaps more than any other hard-to-abate sector , there is a wide range of decarbonisation routes for iron and steelmaking . The decarbonisation imperative and motivation to go green are clear . The questions related to decarbonisation are not “ why ?” and “ if ?”. The questions are “ where ?”, “ when ?”, and “ how ?”.
About the author
Stephen B . Harrison is the founder and managing director of sbh4 GmbH . His work focuses on industrial decarbonisation and greenhouse gas emissions control . With a background in industry , including 27 years at BOC Gases , The BOC Group and Linde Gas , Stephen has intimate knowledge of gases used in iron and steelmaking . He is also an expert in hydrogen , ammonia , and carbon dioxide from commercial , technical , operational and safety perspectives .
Green Steel World | Issue 10 | February 2024 41