The steel industry contributes approximately 8% of global CO₂ emissions, with blast furnace operations accounting for the majority within integrated steelmaking. Although the United Kingdom plans to transition toward electric arc furnace technology, this pathway faces constraints including high electricity prices, limited high-quality scrap availability, and long infrastructure timelines. Therefore, blast furnace ironmaking will remain important in the medium term. No previous study has provided a UK-specific environmental and economic comparison of solid and gaseous reductants within a single framework, which defines the research gap addressed in this thesis.
This research evaluates the environmental, economic, and practical feasibility of charcoal, switchgrass, grey hydrogen, and green hydrogen relative to a conventional coke and pulverised coal baseline. A cradle-to-gate life cycle assessment was conducted for one tonne of hot metal across five midpoint impact categories: global warming potential (GWP), land use, fossil resource scarcity (FRS), water consumption, and mineral resource scarcity. This was supported by data quality evaluation and sensitivity analysis. A simplified economic assessment was performed for charcoal and green hydrogen.
Results show that charcoal reduces GWP by 11% and FRS by 25% but increases land occupation threefold. Green hydrogen reduces GWP by 10% without land pressure but increases water consumption by 17%. Grey hydrogen performs worse than the baseline, while switchgrass provides only marginal improvements. All scenarios achieved a pedigree matrix score of 15 or below, indicating robust data quality. Economically, the baseline remains the lowest-cost option. Charcoal is more expensive due to imported feedstock but offers a lower cost per tonne of CO₂ avoided than green hydrogen, which remains the most costly despite future cost reduction potential.
The findings suggest a phased decarbonisation strategy for UK blast furnace ironmaking, combining immediate operational improvements, short term adoption of certified charcoal, and medium to long-term deployment of hydrogen-based and carbon capture solutions.
