The key to reducing steel emissions may be using aluminum instead

Steelmaking is a major source of difficult-to-abate carbon dioxide (CO2) emissions. Here, we analyze decarbonization pathways for both aluminum and steel by considering five production routes, including the fossil fuel-based processes that are used today and fully-electrified processes under development. We find that on a $/t CO2 basis, aluminum is cheaper to decarbonize than steel over a wide range of projected electricity costs and carbon intensities. Projections for the year 2050 suggest aluminum abatement costs of $9/t CO2 and steel abatement costs of $363/t CO2 by electrification. Furthermore, we observe that if renewable electricity costs decrease enough for green steel to compete with conventional steel, aluminum may be a cost-effective substitute in many applications. Thus, in contrast to the dominant theory of change, an important option for reducing steel emissions may be substitution with low-carbon aluminum.