Towards blast furnace ironmaking decarbonization via alternative reductants: A techno-economic and carbon assessment

Abstract

The steel sector is one of the largest industrial contributors to global CO₂ emissions, making the decarbonization of ironmaking essential for achieving net-zero targets. This study investigates lower-carbon blast furnace (BF) operation through the partial substitution of fossil fuels with waste-derived reductants, linking industrial decarbonization with resource recovery and circular economy principles. A representative European BF-based ironmaking system was assessed under four scenarios: a conventional Benchmark Scenario (BS); the AlterCoal Scenario (AS), in which non-recyclable waste plastics partially replace coke oven coal; the Torero Scenario (TS), where pulverised coal is substituted with bio-coal from torrefied waste wood; and a combined AlterCoal–Torero Scenario (ATS).Life-cycle and techno-economic assessments were conducted to quantify the environmental and economic performance of each pathway. The results indicate reductions in total CO2 emissions of 0.55% (AS), 1.09% (TS), and 1.64% (ATS), primarily driven by the lower upstream carbon intensity and biogenic content of the alternative fuels. Economically, average gross profit increased by 9.3% (AS), 7.8% (TS), and 17.2% (ATS), mainly due to reduced exposure to energy market volatility and carbon pricing. Sensitivity and uncertainty analyses indicate enhanced economic resilience for the alternative scenarios, particularly under elevated coal and carbon price conditions. Overall, the results demonstrate that integrating waste-derived fuels into BF ironmaking can simultaneously reduce emissions and improve economic performance, offering a pragmatic transition pathway for advancing sustainable process innovation in energy-intensive industries.