Exploring the effectiveness of grey literature indicators and life cycle assessment in assessing circular economy at the micro level: a comparative analysis

Purpose: Methods and tools to measure Circular Economy (CE) are in an early stage of development, especially on the micro level, and only limited guidance is available to companies’ decision-making processes related to CE solutions. In this context, the aim of this paper is to explore the suitability and effectiveness of grey literature CE indicators and the Life Cycle Assessment (LCA) method in measuring circularity at product or process level. Methods: The analysis is based on two different comparative case-studies specifically related to the packaging sector, including glass and polyethylene terephthalate (PET) bottles, and to the food waste (FW) management sector, focusing on specific FW treatment activities. A review-of-reviews of CE metrics at the micro level is presented first in order to provide a theoretical overview on this specific theme and identify the available grey literature CE indicators and the role of LCA. Then, inventory data from both case studies are used as input to calculate LCA indicators as well as selected product-level grey literature CE indicators. Finally, the results are compared to critically analyze the potentiality in assessing circularity of these two streams of CE micro level assessment (LCA and CE indicators). Results and discussion: The main findings underscore that despite the common purpose of the selected CE indicators, the results related to the circularity performance may strongly vary depending on the evaluated case study and on the type of grey literature CE indicator that is applied. Regarding the application of the LCA method, the results highlight that, although a product may present high circularity performance, it does not necessarily carry lower environmental burdens. In addition, the LCA method allows obtaining useful information about both the environmental and circularity performance of the assessed case-studies. Conclusions: The LCA method is presented as a suitable and effective method that businesses can apply to start a commitment towards CE. LCA can be considered the basic structured system on which to build a more complete metric framework for quantification of CE, specifically for companies that are aiming to operate more sustainably. On the contrary, grey literature CE indicators may not be always appropriate for assessing specific sectors or effectively contribute to assess environmental sustainability.