(243f) Scope of zero-carbon metal production: State-of-the-art and future prospects

The rapidly growing infrastructure development around the world has led to a continually increasing demand for metal production. The primary energy requirement and green house gas (GHG) emissions associated with metallurgical extraction of structural metals, especially steel and aluminium, is quite high. Integration of renewable energy sources in the metallurgical industry is paramount to achieving the targets set out in the Paris Climate Agreement, 2015.

This work targets the iron and steel industry, which accounts for over 75% of the GHGemissions in the metal production sector. We focus on evaluating the various core reactor technologies for iron and steel production and discuss the opportunities for integration of renewables to eliminate fossil-fuel consumption and achieve reduction in GHG-emissions well beyond those achievable from efficiency improvements and modifications to the current direct reduced iron (DRI) and blast furnace (BF) routes. Relevant technologies evaluated include electrowinnning and pyro-electrolytic reduction of iron ore, solar-thermal integrated electrolysis and hydrogen-based steel making wherein the carbon-neutral H2 production is potentially achieved using PV-electrolysis, biomass gasification, photo-electrochemical route and solar thermal redox water-splitting. The primary energy requirement is calculated after implementation of a simple heat exchange network and pinch-analysis for each process. The potential for CO2-emission reduction for the various technological routes is presented and compared with the state-of-the-art. A case study relevant to the Australian context considering the economic impact and prospects of zero-carbon metal production is also presented.