A Critical Review of Industrial Symbiosis Models

The growing attention on sustainable development themes, in line with an increasing awareness of the exhaustibility of natural resources, has made the traditional linear economic model obsolete. Therefore, the concept of "Circular Economy" was developed to favour products and materials recovery and regeneration. To this end Industrial Symbiosis represents a promising approach to foster the transformation towards this type of economy, based on resource efficiency, sustainable manufacturing, materials, energy, water and/or by-products exchange and sharing between different companies. In this context, the aim of this paper is to present a classification and a critical discussion about existing industrial symbiosis models. According to the presented literature review, industrial symbiosis can be realized thorough the implementation of three different models: (i) industrial symbiosis districts that develop from a bottom-up approach and are based on resources sharing and materials exchanging, (ii) eco-industrial parks that develop from a top down approach and are determined by eco-sustainable infrastructures and systems, and (iii) networks for industrial symbiosis that evolve through cognitive/relational tools and are based on resources supply and demand intersection. The final objective of this study is to evaluate strengths and weaknesses of each model, to explore the applicability in real contexts, and to identify potential economic and environmental benefits (e.g. reduction of polluting emissions and landfilled wastes, economic savings due to reuse of scraps, energy sharing). The study concludes by identifying research gaps, reflecting on possible application of industrial symbiosis and proposing suggestions for future work.