Environmental Trade-Offs of Downcycling in Circular Economy: Combining Life Cycle Assessment and Material Circularity Indicator to Inform Circularity Strategies for Alkaline Batteries

Edis Glogic,Steven B Young,Guido Sonnemann

doi:10.3390/su13031040

Abstract

The application of circularity strategies to improve resource use and recovery should be considered with their potential impacts on the environment. Their effectiveness could be evaluated by combining the material circularity indicator (MCI) and life cycle assessment (LCA) methods. Environmental trade-offs may be underestimated for some strategies given that the loss of material quality with recycling has not been captured within the methodological framework of MCI. The current study demonstrates how significantly this limitation may influence the trade-offs in a case study. The methods are applied to several scenarios for the circularity improvement of alkaline batteries. The joint interpretation of MCI and LCA scores is carried out using waterfall charts and normalized indicator scores. Results suggest that improving circularity generally reduces environmental impacts, although there is large variability among two sets of values. For example, an increase of MCI score by 14% for two recycling scenarios translates to a small reduction of impacts in one case (0.06–1.64%) and a large reduction in another (9.84–56.82%). Observations from the case study are used to discuss the design and scope of MCI use and its combining with LCA. Lastly, we draw on the opportunities of the new comparative approach.

Highlights

We show how trade-offs between circularity and environmental impacts are influenced for several scenarios for the circularity of alkaline batteries
The comparison was carried out in order to highlight how trade-offs are affected given that the loss of material quality with recycling is differently captured by the two methods
The results show that the improvement of circularity often leads to the reduction of environmental impacts, but that scores among two sets of indicator can vary strongly in instances of material downcycling

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Sustainability 2021, 13, 1040 environmental impact categories and indicators with MCI to assess circularity strategies for the life-extension and manufacture of truck tires. Environmental trade-offs were noted for the life extension strategies, while the use of secondary material for tire manufacture was shown to be beneficial for both impact and circularity indicators. While MCI is considered the most complete circularity indicator, there are several methodological limitations associated, including the ability of the indicator to capture material quality loss with recycling [11,12] The influence of this limitation on the trade-offs between circularity and environmental impacts can be better understood by exploring case studies for specific circularity strategies and scenarios that incorporate downcycling. The demonstrated approach and prospective findings are of interest to both industry and academia that require adequate methods to operationalize the circular economy and consider trade-offs in sustainability assessment

Circularity Scenarios and Improvement Routes of Alkaline Batteries

Data Requirements and Modeling Assumptions for LCA

Data Requirements for MCI

Environmental Trade-Offs of Circularity Scenarios

Conclusions