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Industrial symbiosis

Industrial Symbiosis: a model for growth in the circular economy

11. October 2022
industrial symbiosis Aalborg

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Aalborg University

Aalborg University is a key player in energy- and environmental research and education in Denmark. Through cooperation with companies and academia we generate sustainable solutions and meet global challenges

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Global resource use has more than tripled since 1970, while their demand has doubled.[1] This is a trend that is only expected to increase towards 2050. Exacerbating the issue is the fact that material productivity has declined since the turn of the century and is currently stagnating. Unsustainable resource use depletes the supply of resources to a critical level, degrades the environment and contributes to climate change.

Therefore, reductions in material consumption and an increase in material productivity are paramount. A key way we can do this is by keeping materials and products circulating and in use for longer periods.

In essence, we are talking about making our economies more circular, and the end to a throwaway culture. Reshaping our economies in a more circular direction necessitates new approaches and a departure from the established way of doing things. New policies, innovative partnerships and cost-effective solutions are all tools we can utilise to heighten resource efficiency and sustainable consumption and production.

For companies, industrial symbioses have been proposed as a method they can adopt to assist in preserving scarce resources, make their resource use more efficient and sustainable, and even as a way to increase their competitiveness. But what does industrial symbiosis mean in practice? What are some of the tangible benefits for companies participating in an industrial symbiosis?

[1] UNEP 2020, Advancing Sustainable Consumption and Production: Circularity in the Economy of Tomorrow.


Put simply, industrial symbioses are commercial collaborations where companies exchange residual and surplus products such as water, energy, or materials. Normally, the companies are located in close proximity to each other, as long distances can impede the exchange of resources, or remove the business and environmental case for doing so. For companies, it can be advantageous to participate in the symbiosis, as it helps them achieve their environmental objectives (such as reduce CO2 emissions), reduce costs and find a market for their residual and/or by-products.

Located at the top of Denmark, Northern Jutland is the old industrial heartland of Denmark. A thriving entrepreneurial culture and business community remains to this day, where the focus is on transforming the region into an incubator for sustainable solutions. A strong network of actors within companies, ports, the university, municipalities, and utilities, support corporate collaborations to manage resources and increase competitiveness.

It was in this context that the ‘Sustainable Synergies. Facilitated Industrial Symbiosis for Energy and Resource Efficiency’ project was created. Initiated in January 2017, and running until June 2020, Sustainable Synergies was designed to improve the competitiveness of SMEs in Aalborg East by developing green business models that would improve energy efficiency and resource efficiency through a facilitated industrial symbiosis. A collaboration between the Port of Aalborg, the University of Aalborg, and the energy cluster House of Energy, approximately ten attractive symbioses were developed – involving more than 25 companies. In addition, the local business network and the public energy supply organisation were engaged in the project.

Sustainable Synergies commenced by mapping the potential for energy and resource savings on a meta level for all the SMEs in the area. Based on the analysis, companies were identified and invited to participate in the symbiosis. Following this, companies were matched with other suitable companies, and specific groups were established to further develop the collaboration. For example, businesses shared resources or participated in common solutions for the collection and transport of waste. Emphasis was placed on utilising the area’s resources more wisely, and ensuring waste was reused and recycled rather than being incinerated or sent to landfill.

Examples of the symbioses that were established during the project include a local industrial designer that created a new line of furniture using surplus metal, wood and fibreboard supplied by three local companies. The waste materials were transformed into modern tables and lamps with genuinely sustainable credentials and a long lifespan. Another developed a process to recycle the corrugated plastic sheets steel processing companies in Aalborg East receive as a protecting layer between steel sheets. While the plastic sheets are made of pure plastic material and easy to recycle, the volumes of each company have typically been too small to make the logistics of recycling cost-efficient. Therefore, the plastic sheets have typically been sent for incineration along with other waste fractions. Following the Sustainable Synergies project, they are now being collected and transformed into new, high-quality, plastics.

Sustainable Synergies was supported by the European Fund for Regional Development and based at the Danish Centre for Environmental Assessment at Aalborg University.


Industrial symbioses mean less extraction of virgin materials, heightened recycling of water and energy, and less CO2 emissions. For companies, they represent a way to lower their environmental impact and their production expenses.

In the case of the Sustainable Synergies project, the companies involved in the symbiosis have experienced a range of direct and indirect benefits. Direct benefits include a reduction in waste disposal costs and material purchasing costs. For example, companies that sent their surplus resource to another company reduced waste management costs. The company receiving the surplus resource could then in turn save on materials procurement costs. This means that the typical value of a resource exchange symbiosis is between DKK 30-50,000 per year for a small company.

In addition, extra income has been generated through product innovation and new products, as well as created new markets and/or customer groups. The project calculates that DKK 1-2 million annually is the typical direct value of symbioses that create new products or product innovation.

Concretely, a number of positive environmental results have been achieved. Over the project’s lifespan, energy consumption was reduced by 11,000 gigajoules and materials consumption was reduced by approximately 2,600 tonnes FE-equivalents. On average, each company saved 264 MWh of energy, an amount that corresponds to the energy consumption of eight households. Furthermore, the collaboration has contributed to reducing annual CO2 emissions by 10,000 tonnes. This means that each symbiosis created reduced CO2 emissions by 800 tonnes, which corresponds to the CO2 emissions of 100 Danish residents.

Also worth mentioning is the fact that the reduction in greenhouse gas emissions was eight times higher than estimates made at the project’s outset, and material reduction 10 times greater.

Finally, a number of less tangible benefits such as improved image, capacity and competence building, improved company culture and work moral, social benefits and job creation have also been cited by the companies that participated in the Sustainable Synergies project.