Biotechnologies: A Pathway to Net-Zero CO2 Emissions Steel?

Abstract

Iron and steel decarbonization is at the forefront of global greenhouse gas (GHG) abatement discussions. Social and legislative pressures to achieve “net-zero” have accelerated steel producer efforts to find solutions to reduce GHG emissions. Initiatives to transform the traditional methods of fossil-fuel based iron- and steelmaking abound examples include hydrogen injection in the blast furnace, hydrogen-based direct reduced iron, and carbon capture and storage (CCS) of off-gases. Implementation of these transformational technologies poses significant technical and economic challenges. This has led to the exploration of other decarbonization pathways, including biotechnologies, as part of the push to produce “net-zero” steel. Biotechnologies refers to the utilization of biological processes, at the cellular and biomolecular level, to generate desirable products or outcomes, such as those that can heal, feed, or fuel people, and the planet [1]. Not all biomasses are equal, and not all biotechnologies are suitable for every iron and steel process. Biomass can be used in the steel value chain as a reducing agent and energy source. Other emerging biotechnology applications include microalgae production via photosynthetic to capture CO2 in off-gases [2], and bioethanol synthesis via microbial fermentation of a CO rich off-gas. These biologically based end-of-pipe treatments use microorganisms to valorize steelmaking carbon emissions while abating them. This paper describes the production and use of biomass or biocarbon as a fossil-fuel replacement and the production of microalgae from process off-gases in the steel value chain. Specific applications in the blast furnace-basic oxygen furnace (BFBOF) and electric arc furnace (EAF) steelmaking routes are described.