An environmental assessment framework for circular steel products

The implementation of the circular economy is crucial to combat climate change especially in energy- and carbon-intensive sectors like the steel industry. It requires the environmental assessment of circular interventions to steel products to ensure that they are in line with targets of the circular economy – increase of resource efficiency and sustainability. Based on previous case studies and established methodologies, an environmental assessment framework is suggested and applied. It comprises a Material Flow Analysis to quantify selected mass-based indicators to evaluate the parameters of circular economy, as well as a Life Cycle Assessment to quantify the difference of the environmental impact. The application to a case study in the metalworking industries shows that the implementation of repurposing to a machining knife and hand tools contributes to all circular economy strategies - narrowing, slowing, and closing. At first, however, the circular intervention did not lead to a reduction of the environmental impact. It was found that the optimization of share of secondary material, energy mix, grinding, and transportation can lower the environmental impact of the circular compared to the conventional product system. Considering the increased product functionality, the environmental performance of the circular product system is superior. The study shows the importance of integrating assessment methods covering the resource level and environmental sustainability since focusing only on the resource efficiency can be misleading. At the same time, it stresses the need to apply environmental assessments in the product development stage to design environmentally sustainable and resource-efficient product systems.