Two or more companies exchange resources, turning the waste of one into inputs for another: this is the principle behind industrial symbiosis.
Although circular economy has been a topic of much discussion – and for quite some time – moving beyond the linear "take, consume and dispose" model is far from straightforward. According to the European Environment Agency, in 2023 the material footprint of the European Union – that is, the quantity of resources needed to produce the goods and services consumed by its citizens – stood at 14.1 tonnes per capita. That same year, the circular material use rate in Europe was just 11.8 per cent, a figure that has remained largely unchanged since 2016. Recycling, in and of itself, works: the problem lies in the volume of materials entering the economic system and the way in which they are used.
Many companies have already begun to act within their own boundaries, working on product redesign, waste reduction and material recovery. These are important steps, but they can only go so far. If the goal is to turn the circular economy into something that produces effects on a larger scale, the dimension of the individual firm risks being insufficient: what is needed is creating connections between companies, territories and supply chains. This is where industrial symbiosis comes into play.
An industrial symbiosis arises when two or more companies begin exchanging resources – materials, energy, water, by-products – transforming what would be waste for one into a useful input for another. The most immediate case is that of a company producing a residue and another that can use it in place of a virgin raw material. But the examples can vary enormously: excess heat recovered to power buildings or production processes, water reused in another industrial cycle, food waste or agricultural by-products valorised in other supply chains. The point is not to "recycle better" downstream, once the waste has already been generated, but to intercept flows before they become an environmental and economic cost.
From this perspective, waste management is only one of the areas of intervention in industrial symbiosis. The logic is broader: understanding which resources circulate within a territory, where surpluses are generated, where compatible needs exist, and what technical, economic and regulatory conditions are required for an exchange to be viable. For a company, the question is therefore not merely "how do I dispose of this waste?" but "could this flow have value for someone else?" And, at the same time, "can I replace a virgin raw material with a by-product available nearby?"
Geographic proximity matters greatly, because exchanging heat, water or heavy materials only makes sense if the logistical, technical and regulatory costs do not outweigh the benefits. This is why industrial symbioses often emerge in areas where there is already a concentration of productive activities, infrastructure, energy plants, water networks or port facilities. However, simply placing companies side by side is not enough. What is needed is data on incoming and outgoing flows, trust between operators, sustainable economic agreements, regulatory clarity and someone to hold together all the parties involved.
This is where facilitation comes in. Symbioses do not always arise spontaneously. A coordination structure can help map flows, identify possible matches between supply and demand for resources, seek funding, support technical testing and build trust between parties that may never have collaborated before. It is not merely a technical matter: trust, familiarity and connection between companies are necessary conditions for exchanges to function over time.
The benefits associated with industrial symbiosis are now well documented and can be economic, environmental and social. For businesses, this approach can help reduce costs related to resource procurement and waste disposal, generate additional revenue through the valorisation of by-products, and reduce exposure to resource scarcity and raw material price volatility – all while fostering innovation and gaining a competitive advantage. On the environmental front, it reduces the need for virgin raw materials, waste generation, CO2 emissions and other greenhouse gases, and transport-related emissions. The potential benefits are also social and territorial, including job creation, a contribution to sustainability goals, and a greater capacity to attract skills and talent.
One of the best-known experiences is that of Kalundborg, in Denmark, which dates back to the 1960s and has since become an international academic case study. The guide published by Kalundborg Symbiosis distinguishes between a single symbiotic exchange and a true industrial symbiosis network. In the former case, two companies collaborate on a specific flow: for instance, one provides heat, water or a by-product, and the other uses it. In the latter case, multiple companies are connected to one another through several exchanges: the residue of one becomes an input for a second, the by-product of the second may be useful to a third, and so on. It is this shift from a one-to-one relationship to a network that allows industrial symbiosis to become something far greater than a single recovery project.