Control of greenhouse gas emissions from electric arc furnace steelmaking: evaluation methodology with case studies

The energy intensive nature of electric arc furnace (EAF) steelmaking necessitates that efforts to reduce greenhouse gas (GHG) emissions will affect steelmakers directly and/or through electric power producers. A model of GHG emissions from an EAF meltshop has been developed using the life cycle assessment approach. Direct and indirect sources of GHG gas emissions are estimated and ranked. Furnace combustion optimisation was evaluated in case studies conducted on a Canadian conventional EAF and a British scrap preheating `shaft' furnace. The analysis assumed 32 and 68% fossil fuel electricity generation, respectively. These case studies show that indirect GHG emission sources, in particular electricity generation, are more significant than direct emissions from the EAF. For the conventional EAF, offgas analysis and improved combustion control reduced electricity consumption by 40 kWh t^-1, costs by US$1·05/t, and GHG emissions by 20 kg CO₂-eq./t. For the shaft EAF, real time offgas monitoring and closed loop burner control reduced electricity consumption by 25 kWh t^-1, costs by US$3·6/t, and GHG emissions by 15 kg CO₂-eq./t. The case studies show that combustion optimisation using an EAF offgas analysis and combustion control system provides greater electricity, cost, and GHG reductions than previously reported in the literature.