Coupling Material Flow Analysis and Network DEA for the evaluation of eco-efficiency and circularity on dairy farms

Society is facing different challenges such as resource scarcity, climate change, and food security. Thus, proposing methodologies to assess the sustainability of promoted circular systems is essential to balance economic benefits and the preservation of nature. The eco-efficiency concept seeks to achieve sustainable management and production, creating more value and reducing resource consumption and environmental impacts. This paper proposes a new method for eco-efficiency and circularity assessment through a combined input-output oriented approach of Material Flow Analysis (MFA) and network Data Envelopment Analysis (DEA). Overall, the definition of boundaries and the quantification of inputs and outputs of the system are carried out, and then, the DEA assessment establishes eco-efficiency levels and targets for inefficient systems. The composite method was applied to evaluate the eco-efficiency and circularity of 50 dairy farms located in Galicia, Spain. To do this, a two-stage network structure is considered, evaluating the stages of feed crop (first stage) and milk farming (second stage), where cattle manure is valorised as organic fertilizer to feed crop farming, closing the loop. The results indicate that the first stage presents the lowest efficiency indexes. In this sense, the main reductions should be focused on pesticides and fertilizers as improvement actions to be implemented. Moreover, on average, efficient dairy farms present a higher level of circularity than inefficient ones. In this context, this method seeks to be useful to inform decision makers about their eco-efficiency performance to achieve sustainable and efficient circular systems. (c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.