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From the Field

Closing the Loop or Looping Close By?

Metabolic Nodes to Challenge the Spatial Extent of the Circular Economy

Marine Frantz and Gabriel Renault explore the spatial dimension of the circular economy, particularly in regard to waste management issues. Based on research conducted in Lille, France, they outline steps municipalities could take to develop a more local recycling industry.

Series: Urban Wastes, Present and Future

In the last decade, the notion of a circular economy has been imposed as a major public policy feature at various scales of governance, from European to local. Circular economy strategies offer a way to depart from linear forms of waste management by systematising repurposing (Kirchherr et al. 2017). Yet, the spatial dimension of the circular economy is largely overlooked today, especially as it deals with waste management issues (Bahers et al. 2017; Dermine-Brullot and Torre 2020). This omission is problematic because it fails to address some major externalities entailed by a region-wide or global circular economy, such as greenhouse-gas emissions from transport or treatment processes.

An alternative and complementary approach, namely territorial ecology, offers an answer to the missing spatial component of current European circular economy policies. Territorial ecology measures material flows and how they unfold in space (Barles 2010). Yet, although quantitative studies seem to have taken off (see, for instance, Barles 2009), research on how actors or organizations manage material flows remains underexplored (Bortolotti 2020; Mongeard 2017).

Focusing on actors offers a complementary approach to the more common material flows analysis (MFA). It provides a deeper understanding of the reasons that a circular economy is, or indeed is not, local in its nature. In a case study of the European Metropolis of Lille (Métropole Européenne de Lille in French; hereafter MEL), we analyzed the local metabolic landscape, from which key infrastructural sites were singled out. Major flows going in and out of the metropolis were passing through a limited group of places, which we labelled “metabolic nodes.” These metabolic nodes centralize and redistribute material flows at different scales and are thus pivotal in determining the nature of a place’s metabolism. The study focused on these places and on the people that run them to bring a new understanding of how the flows are directed from both a contractual and a spatial point of view.

This article identifies the main metabolic nodes dedicated to waste management flows in MEL, and presents analysis based on about fifty interviews with actors involved in the day-to-day operation of those places (plant managers, executives and engineers) and visits to the various infrastructures’ processing lines. [1]

The location of recycling plants: between proximity and globalisation

Waste management practices can vary according to the type of waste, though most processes are similar. First, waste is discarded in particular places. It is collected, sorted and then recycled or eliminated through different technological interventions. Each of these steps occurs in metabolic nodes. The location of metabolic nodes varies greatly depending on the type of waste flow (e.g. inert waste from the construction sector or waste generated by other economic activities), but also on the step of the treatment process.

In MEL, metabolic nodes are loosely scattered within the metropolitan perimeter. They are not necessarily located in close proximity to the “urban mine” (Cossu and Williams 2015). Metabolic nodes for municipal and commercial wastes typically act as sorting and transfer centers, from which locally-collected waste is distributed to distant countries to be treated or recovered.

In the MEL, we observed that the geography of inert construction waste treatment is quite different from municipal or commercial waste flows. Metabolic nodes for construction waste are anchored locally. Sorting centres, recycling centres, landfill sites—in short, all the steps of recycling process for this industry—are contained within the MEL. This local dimension is acknowledged and defended by local firms: “It’s a microcosm, we are local, not global” (Plant manager, Briquetteries du Nord, 19th of January 2021). A small part of the flows observed travel longer distances, but do not reach farther away than neighbouring regions or countries.

Spatial fragmentation of waste flows through the lens of firms’ practices

Several entangled factors shape the geography of waste flow. Market conditions constitute a powerful driver, but regulations gaps and physical characteristics of the waste should not be underestimated. As an illustration, we can turn to the treatment of wood waste. The MEL is located next to Belgium’s border, leading to a flight of flows outside of the MEL perimeter towards Belgium. This flight of flows is partly due to a market condition: in France, the outlet for wood waste repurposing has reached a saturation point. In Belgium, the high number of biomass plants makes this kind of repurposing easier: “The French market for wood is completely flooded, some firms have to export worldwide using container ships. That is not our case, because we can export to close-by Belgium, but the fact is that there is a clear lack of biomass plants in France” (Plant manager, Veolia, 26th of January 2021).

An existing regulatory gap between the two countries also pushes French firms to export their waste to Belgium, where it is allowed to be burnt even when it is of low quality (this practice is forbidden in France). The regulatory differential between France and Belgium also points towards different recycling strategies regarding wood chips, and the larger debate on material repurposing as opposed to energy recovery (Knauf 2015). As per the hierarchy of waste treatment formulated by the European Union, reuse of material has a better environmental impact than energy recovery in the framework of a circular economy. The energy recovery—burning—of wood waste produces gas emissions that impact the environment. This has created some ambiguity from the part of the European Union. Having until recently supported the waste-to-energy industry (Behrsin 2019), it now appears much more critical on its detrimental outcomes (Gardiner 2021).

Belgium’s vicinity, coupled with both facilitating conditions stated above, enables a kind of regional internationalisation of waste flows. Other waste flows however obey a truly global pattern. Distance separating the various metabolic nodes thus increases dramatically. For instance, flows of (scrap) metal waste are directed differently, with respect to the expected added value of the recycled substance. In this case, regulation differentials appear as a secondary driver, at best. Once ground and prepared, metal waste is directed towards smelting plants, either in Europe or Asia depending on the type of metal. Then, part of the recycled metal— but not necessarily the one that has been sent—comes back to the MEL as a finished product, to be used by local firms. Today, China constitutes a main receiver of such flows, because of its low cost, coal-powered, smelting plants. Interestingly, virtually all individuals interviewed during the enquiry mentioned the movement of deindustrialization in France that forced the industry to export its waste further and further away. To the extent that metal waste management practices correspond to a form of circular economy, it appears to be a European and/or worldwide circular economy, with the various externalities that it entails. Though technically complying with the EU’s circular economy mandates, analysis of metabolic nodes for wood and metal indicates that MEL is still relying on geographies and technologies of conventional recycling, rather than truly implementing circularity.

The construction waste management industry exhibits distinct logics. The tension between added value and transport costs is central in explaining the industry’s locally-anchored nature. Construction waste is bulky and heavy and most metabolic nodes within the industry rely on transport by road. As the added value expected from construction waste recycling is rather low, transport costs become crucial to the viability of operations. Put more clearly, sorting or recycling centers have to locate themselves close to the waste deposit in order to be profitable. Therefore, they tend to be located close to urban centers. Most of them are operating within a short range of the urban mine, a few dozen kilometers at the most, as shown in Figure 1. Contrary to what could be seen in the case of wood or metal waste industries, the metabolic nodes are distributed in space in such a way that they can attain a high cover rate of the MEL’s perimeter. A handful of recycling centers are located adjacent to alternative modes or transport (inland navigation or railway). Thus, the range in which they operate is augmented significantly. For instance, some plants within the MEL use inland navigation to trade with other metabolic nodes in the Île-de-France region (a few hundred kilometers from there), or in Belgium. But the larger share of facilities that lack rail connections maintain narrower geographies of trade and reuse.

How can municipalities work towards a grounded circular economy?

The study of MEL’s metabolism demonstrated some limits of its waste management system, but also goes a long way to identifying some opportunities to improve it. Even if the waste management system is largely made up of private actors, local authorities can still significantly influence its organisation. First, they can make up for the missing metabolic nodes by encouraging location and expansion of industries specialised in recycling or repurposing. While some of the power in the hands of local authorities enables them to help coordinate local firms, re-anchoring industries locally would entail a dialogue with other public bodies (e.g. regions, the state, etc.). A second lever that local authorities such as the MEL could use in order to create a locally anchored circular economy is to foster better recycling practices. In order to do so, additional land would be required. Local authorities could help integrate local recycling plants, which are associated with specific constraints, and sometimes tensions. Finally, local authorities could define stricter constraints in public procurement practices, regarding the incorporation of recycled material. All this would constitute a first step towards the emergence of a locally-anchored recycling industry, as opposed to the globally driven linkages that still dominate some of the main recycling industries today.


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Further reading

Learn more about the metabolism of the European Metropolis of Lille: (French only)

To cite this article:

Marine Frantz & Gabriel Renault, “Closing the Loop or Looping Close By?. Metabolic Nodes to Challenge the Spatial Extent of the Circular Economy”, Metropolitics, 7 February 2023. URL :

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