Unexpected water impacts of energy-saving measures in the iron and steel sector: Tradeoffs or synergies?

Moving towards integrated governance of water and energy requires balancing tradeoffs and taking advantage of synergies through specific technology choice. However, the water-energy conservation relationships of individual conservation measures in industries other than the water and energy sectors have not been investigated in detail. This study develops a hybrid model to estimate the associated water impacts of individual energy conservation measures, using China's iron and steel industry as a case study. The results reveal that water-energy tradeoffs exist in the production process adjustment, which is conventionally promoted as a key energy-saving measure in iron and steel industry. It is found that replacing the Blast Oxygen Furnace (BOF) process with the Electric Arc Furnace (EAF) in 2007 could save 131-156 kg coal equivalent (kgce) (13.2-15.7%) of embodied energy per ton of crude steel (tcs) at the expenses of an additional 2.5-3.9 m3/tcs (10.6-16.4%) of water footprint. Nineteen energy efficiency technologies are studied in this research, and most of them are identified as having water-saving synergies except for the Low Temperature Rolling Technology. Taking these water impacts into consideration can update the priority ranks of the technology choices and inform policy decisions. Although this study focuses on China's iron and steel sector, the methods and analysis can be extended to other countries, sectors, technologies and environmental impacts.