Steel circularity in New Zealand’s construction sector: A critical review of the option space
Steel is an indispensable material in modern construction, but the manufacturing process contributes significantly to carbon dioxide (CO2) emissions. By increasing recycling and reuse, we can continue to benefit from steel's practical advantages while reducing the need for primary production. In New Zealand (NZ), the planned construction of an Electric Arc Furnace (EAF) will facilitate domestic recycling, but steel reuse remains underutilised.
This study analyses NZ's current and future steel stocks and flows using 28 potential scenarios with various rates of recycling, reuse, scrap collection, and grid emissions factors. Real and domestic emissions reductions are compared, considering the impact of interventions on other countries’ emissions. Further, through a survey (n=34) and interviews (n=15) with industry stakeholders, barriers to and solutions for steel circularity are explored.
Results show the EAF, in combination with improved scrap collection rates, has a pronounced impact on emissions reductions. A practical, sustainable future scenario was developed with EAF capability, 30% structural steel reuse, 93% scrap collection and a 100% renewable grid, resulting in an 870tCO2 (58%) annual emissions reduction for the steel industry. Applying similar circularity interventions to the entire steel industry would allow the industry to reach net-zero by 2050. A future supply chain and causal loop diagram (CLD) have been developed and indicate the importance of a more integrated value chain, digital solutions such as a material passport system, circularity education and government support.