Effects of waste recovery on carbon footprint: a case study of the Gulf of Bothnia steel and zinc industries

This article analyses the impact of waste recovery on climate change mitigation on a regional scale. We focus on the EU End of Waste (EoW) policy, which aims at reducing negative impacts on the environment through the minimization of generated waste. At the same time, the EU climate objectives set challenging goals for the industry to lower greenhouse gas emissions. We argue that the goals of these two policies are conflicting: under certain circumstances, the EoW will lead into increased greenhouse gas emissions because of a number of negative feedback effects that function on multiple spatial and temporal scales.To assess the effects of waste recovery on greenhouse gas emissions, we carry out a consequential life-cycle inventory on a proposed industrial ecosystem around the Gulf of Bothnia between Finland and Sweden. The system recovers currently unutilized steelmaking dust and slag from four steel mills in Finland and Sweden and converts them into iron and zinc raw materials in a novel rotary hearth furnace. The recovered iron is led back into the blast furnace of one of the steel mills and zinc is treated in an existing zinc plant. In the European scale, the model system is significant in size, serving thus as a model for integrated EoW and carbon footprint assessments in other similar cases within the EU.The analysis reveals the relative greenhouse gas emissions from raw material extraction and production, heat and power generation, transport and the production process itself, in comparison to the present system with limited material recovery. To test the model viability, we conduct a sensitivity analysis with respect to increasing energy and production capacity. Our analysis shows that from the point of view of a single operator, material recovery may bring noteworthy reductions in greenhouse gas emissions. If the scale of the assessment is expanded beyond the confines of a single plant, however, we find limited potential for reducing greenhouse gas emissions through further recovery of steelmaking residues. In conclusion, we provide policy recommendations with which the EoW paradigm can provide better support for climate change mitigation on a regional scale.