1. Introduction
Why Industrial Symbiosis? What’s the point? Industrial Symbiosis (IS) is a collaborative or collective approach to resource management (Mirata 2018). IS serves as a means to achieve ‘Circular Economy’ and ‘Geen Economy’ (ends) by creating synergistic relations between industries to exchange materials, energy, water and other by-products (Chertow 2000, p. 314). As follows we break down these different concepts to shed some light onto how they differ and in what ways they are interrelated.
The concept Circular Economy was first formalised by Pearce & Turner (1990) drawing on the principle that “everything is an input to everything else”. ‘Circularity’ implies moving away from a linear model of resource utilisation: extraction – production – consumption – disposal, to a circular model or closed-loop system, which minimises waste and the utilisation of virgin resources and maximises their lifespan via reusing, repairing, refurbishing, and recycling. The bottom line is that resources are limited and that human consumption patterns come with a heavy cost to the natural environment and threaten the survival of society in the long-term. Now, the wicked problem lies in the question of how to reduce resource utilisation without harming the economy or even enabling economic prosperity. From this question stem concepts of circular economy, green growth, green economy and green transition, all of which entailing a broader transformation of the social, economic, institutional, and technological systems to meet the principles of circularity.
The quest of transiting onto a green economy demands de-coupling economic growth (value creation) from resource utilisation. A central way to do this is via ‘valorisation’ of resources (including waste-streams), which means capturing the highest possible value per every unit of ‘X resource’. Waste-to-energy is perhaps the simplest way to give value to waste (or resource); however, it is also the lowest possible value extracted and the quickest path to end resources lifespan. For illustration, the ‘bio-pyramid’ in Figure 1 shows how the more complex the product extracted from a resource is, biomass in this case, the higher its value and the lower the volume needed. Variations of this commonly used pyramid scheme set a hierarchy of the economic value of different applications of biomass, as well as the chain of applications that can be given to residuals at any step of the ladder.
Besides the additional profits that producing more complex products generates, Figure 1 also shows the spillover effects generated to the broader economy in terms of jobs. In this case, estimations made for the forest bioeconomy in Canada, more advanced product categories generate higher number of jobs. Biofuels create fewer jobs as they require the least value-added processing, whereas biomaterials, engineered wood products used in construction sector, and biochemicals generate the highest number of jobs in relation to volume of biomass needed to produce them (Government of British Columbia, 2024). Furthermore, it can be assumed that the jobs created in more complex processing industries are also better paid than in low complex industries, generating further trickle-down benefits for the host economy.
This shows in practical terms how valorisation can help de-coupling economic growth from resource utilisation. Moreover, valorising biological resources (biomass) is also a way to replace the use of non-renewable fossil and mineral-based resources, such as fuels, plastics, glues, chemicals, etc. A key focus is therefore placed on the potential of the bioeconomy in simultaneously driving the circular economy and replacing fossil fuels.
Despite the elegance of resource pyramid schemes, the practical implementation is far from simple. The production of biofuels, for example, requires different skills, knowledge, technologies, industrial processes and capacities than those required to produce biochemicals or biomaterials. In essence, they are different industries. Therefore, business ecosystems and value chains need to be arranged in such a way that the flow of material and human resources is possible (as in practically and economically viable) between different industrial facilities and uses (markets). This calls for innovative business models and institutional arrangements to create new relationships between companies, authorities, consumers and a broad range of intermediaries, such as universities, institutes, incubators, financiers, etc.
Valorisation of resources is not necessarily bound to symbiotic relations between companies. Indeed, it is vastly common that the use of residues and side-streams of resources are reutilised and repurposed within companies themselves, or within a company/corporate group. This, however, requires companies to build up capacity in industrial processes, develop products, and explore markets beyond their core or original business. This may be desired as a strategy for the company to maximise profits with their available resources, reduce their environmental footprint or simply to retain control over the value chain. However, it can also be the result of a missing link in the supply chain. A company may not be able to identify an external partner willing to fulfil the complementary function needed for them to pass on their side-streams or products further, and as result assume that new responsibility internally. One complex example of this is Martinsons, a company based in north Sweden, which started in 1939 as a sawmill and later began producing engineered wood materials. When regulatory reforms in 1995 opened a window of opportunity to build multi-story buildings made of wood, Martinsons faced a hesitant response of construction companies, developers and financiers. As a result, the company bypassed existing business ecosystems by creating its own construction and design company (Giacometti et al., 2024). More recently, Martinsons was acquired by Holm, a forestry company, capturing even more segments of the value chain under a single roof (ibid.).
However, in many other cases valorisation occurs via resource flows between different companies and users. This may occur either via simple business transactions: Company A purchases the residue resources from Company B, or via more formal co-operation between mutually beneficial arrangements. Hence the term ‘symbiosis’. The bottom line is that IS is not limited to a transaction but is characterised by a deeper form of co-operation and sometimes co-dependence between firms. Co-operation and co-dependence deliveries additional benefits than the sum of their independent activities. In simple terms: ‘1 + 1 = 3’. Resource flows under symbiotic relations may or may not occur between geographically proximate ‘partners’, however, the concept of IS is generally used when firms are closely co-located, either within industrial parks or at regional level (Paquin 2009).
Now, IS can exist on mutual accord between two or more companies, or it can be facilitated and coordinated by an umbrella entity. For instance, the IS networks in Kalundborg, Denmark and those in Norrköping, Helsingborg, Stenungsund, and Örnsköldsvik in Sweden emerged spontaneously in a self-organising form in response to identified opportunities for interaction and material exchange (Mirata 2018). In these cases, supporting structures framing the collaboration came afterwards to facilitate further development. In contrast, the Rotterdam harbour complex or the Sotenäs symbiosis network in Sweden emerged by means of external facilitation (ibid.). The coordinating entity can be some kind of ‘eco-industrial park’, a cluster organisation, or in several cases a local or regional authority. Often, the initiative starts in the form of a project and then evolves into a self-sustaining business-led association. Depending on the specific arrangement, the coordinating entity may be tasked with facilitating dialogue, assisting in the discovery process of synergistic opportunities (e.g., mapping material and energy inputs and outputs), identifying the possible steps ahead, and addressing the practical and legal challenges to establish symbiotic ties.
Besides increasing resource productivity, IS has a political and social significance due to its efficacy in closing the resource loop and cutting the ecological footprint of industry. Therefore, IS initiatives tend to involve a series of other actors besides firms. Authorities at multiple levels and across sectors, incubators, universities, finance entities, among others are often involved. The intensity of involvement is typically boosted with the sponsorship of funds aimed for R&D, competitiveness, regional development, structural change, or supporting sustainability transitions. These may come from national, EU programmes, as well from private and other external funders. Moreover, municipalities are incentivised by their own strategies and goals which have generally incorporated a path towards meeting the Agenda 2030. Thus, municipalities have become increasingly interested in leading the establishment of IS ventures and are often partners themselves via their municipally owned waste management companies, as investors in biogas plants, or as buyers of biofuels in their local public transport services and other procured goods. Therefore, IS tends to evolve around complex co-operation arrangements.