Blast furnaces are an integral part of traditional steel production, though they are also significant sources of greenhouse emissions. Notably, for every ton of steel, approximately 1.85 tons of carbon dioxide (CO₂) are emitted. Moreover, 11% of the global CO2 emissions are produced from the steel industry, with most coming from blast furnaces. Reducing emissions from blast furnaces has thus been a matter of research for quite a long time, and Japan’s biggest steel manufacturer says it cracked the code using heated hydrogen.
Nippon Steel recently made advancements to the hydrogen injection process, where hydrogen is used together with coal to reduce blast furnace emissions. According to the company, a 43% reduction is possible with the process. That’s certainly significant, but it’s important to note that the industry’s long-term sustainability goals will require hydrogen-based direct iron reduction (H2-DRI) to turn iron ore into iron. The H2-DRI process emits only 0.05 tons of CO2 per ton of steel, while the traditional coal-based blast process produces 2 tons of CO2 per ton of steel.
The Japanese steel maker’s process will work as an interim solution, though. It involves a hydrogen pre-heating technique, which increases the temperature of the air blown into the furnace, balances heat loss, and increases overall efficiency. In typical hydrogen-based steelmaking, the endothermic reaction that occurs when hydrogen reduces iron ore can lower furnace temperatures, limiting the amount of hydrogen that can be blown into the blast furnace. This adjustment resulted in a 10-percentage point improvement over previous emissions reduction rates of 33%, ultimately reaching the record-setting 43% reduction.
Nippon Steel’s hydrogen trial is part of the Super Course 50 program, which is backed by Japan’s Green Innovation (GI) fund. Looking ahead, the steel manufacturer wants to scale the technology to its 4,500-cubic meter No. 2 blast furnace at Kimitsu. In the next phase, hydrogen-based gas generated within the steel mill will be used to help Nippon Steel reach its goal of halving emissions from its large blast furnaces.
