Limits on the integration of power to gas with blast furnace ironmaking

This article compares 16 Power to Gas integrations for blast furnace ironmaking by using 17 key performance indicators. The study includes 4 types of PtG (PtH₂, PtSNG using pure CO₂, PtSNG using treated BFG, and PtSNG using BFG), two types of blast furnaces (air-blown and oxygen) and two types of fossil replacement (coal or coke). The blast furnaces are modelled using the Rist diagram, validated with literature data (<2% deviation). For most cases, the decrease in total CO₂ emissions is around 150–215 kg_CO2/t_HM per MW/(t_HM/h) of electrolysis. The energy penalty (in terms of electricity consumption) was found to be mostly independent on the size of the PtG plant, but greatly dependent on the type of integration (10.1–20.6 MJ/kg_CO2). If significant CO₂ reductions are aimed, self-sufficiency in electricity consumption will not be achieved. In practice, the maximum PtG capacity to install is limited by the decrease in the flame temperature. In this context, the PtSNG integration consuming treated BFG, applied to OBF for coal replacement, provides the best results. Assuming a 500 t_HM/h blast furnace, the PtG capacity of this concept could be as large as 490 MW and avoid up to 21% of the CO₂ emissions.