Industrial symbiosis in the circular economy

industrial symbiosis in the circular economy

Industrial symbiosis is a system in which corporations exchange their waste, by-products, or emissions among each other, in order for the waste that has been generated by one company to be used as a raw material by another company.

The possibilities for such exchanges are endless: waste water from a paper mill is routed to an aquaculture farm, leftover woodchips from a timber processing plant are turned into coals at a charcoal factory, organic waste from a food packaging plant is used as agricultural fertilizer.

Certain eco-industrial parks, such as Rizhao Economic and Technological Development Zone in China or Kalundborg Symbiosis in Denmark, take these symbiotic exchanges to the truly circular level. They do this by coordinating the flow of energy, water, and material between companies in the industrial park to such a degree that nearly all waste material generated within the park is processed as a raw material by another company on the complex.

Map of the energy, water, and material exchanges between companies in Denmark’s Kalundborg Symbiosis eco-industrial park. Source: Energy Crossroads

Industrial symbiosis eco-industry parks are circular economies on a small scale

Just as within the circular economy materials never drop out of the system as waste, with industrial symbiosis input and output is circled perpetually amongst industries, and ‘waste’ is never discarded as waste but rather is used as a resource.

Such material exchanges create an industrial ecosystem that mimics the exchange of materials occurring in natural ecosystems, where materials flow in closed circular loops out of one entity back into another. Because of these closed material loops – meaning that the materials are kept within the system – there is reduced dependency on virgin resources and energy, as well as a reduction of emissions and waste streams.

The biggest reason why the economy needs industrial symbiosis is the alleviation of stress to our environment that occurs when material loops are closed. But regardless of its positive impact on the environment, industrial symbiosis is just smart business. Instead of having to manage and finance the logistics of transporting and processing their waste, the company can instead hand it over to an industry who will gladly accept it as a source of material for their own production process, making industrial symbiosis mutually beneficial for all businesses involved.

However, in order to roll out industrial symbiosis on a large scale, there need to be further developments in the management of waste material flow between industries. As it currently stands, it is still more expensive and complex for a business to transport and process another company’s waste material than it is for that business to simply buy the naturally-sourced material. This kills much of the incentive for businesses to adopt industrial symbiosis into their processes. Furthermore, the coordination and logistics of inter-industrial waste material trade – in other words, which industry should trade what with who – are intensely complicated, especially when on a scale larger than one eco-industry park.

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