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Industrial symbiosis: Building on Kalundborg's waste management experience

Stefan Gulipac

The small Danish city of Kalundborg is a leading light for effective industrial waste management, as Stefan Gulipac explains.

At first glance, there is nothing special that could differentiate the small city of Kalundborg, with a population of just 16,000 inhabitants that lies 110 km west of Copenhagen, from other typical Danish towns. Beautiful nature, a picturesque fjord harbour and rococo style architecture, make it a perfect destination for a family weekend getaway.

Yet, if one overlooks the beauty of the surrounding landscapes and the cultural heritage monuments - the five spired Church of Our Lady (which is said to have a close association with the king Valdemar I) being one of these - then one could be pleasantly surprised to discover the presence of a large industrial park that coexists in harmony with the nearby surroundings. What is more thrilling about the region in question is the fact that the industrial activity started in 1972 and laid the foundations for cooperation between the companies based in Kalundborg and the municipality itself. Over time, the collaboration has nourished a sentiment of synergy among the local based companies that lead to the creation of an industrial ecosystem, nowadays known as Kalundborg Symbiosis. It has become an essential part of the Kalundborg community.

New industrial revolution

It is not an exaggeration to claim that Kalundborg is on the verge of setting off the 21st century industrial revolution, with the subject of waste management being approached from an eco friendly position. The notion of innovative waste management in Kalundborg appeals to masses due to its conceptual simplicity and the huge potential it has to offer in terms of rationalising the cycle of input and output.

In short, the Kalundborg Symbiosis is based on a mutually beneficial partnership among local authorities, businesses and industries, where the residual by-product of one enterprise is used as an input resource by another enterprise - closed loop fashion.

Such an innovative, yet simple approach in dealing with waste resulting from industrial activity in the region, has given birth to a long lasting collaboration between public and private organisations. This has lead to environmental benefits and cost savings of $160 million. According to Susan Erkman, the head of the Industrial Group at the University of Lausanne specialising in industrial ecology, the Kalundborg cooperation amounts to tons of reduced waste emissions and recycled waste resources each year (Erkman, Vers une écologie industrielle, Editions Charles Léopold Mayer, 1998), as seen in Figure 1.

For others, an industrial cooperation similar to the one in Kalundborg, would require an initial investment ranging from $70 million to $100 million, with the payback being achieved within five years period. The financial rewards for engaging in such a bilateral partnership are conditional on the revenues that come from selling the waste products and from reduced costs for resources (raw materials).

Flexible and self-sustaining

The beauty of this system is subject to its flexibility and self-sustaining nature. It is totally self-sustaining and does not require a central authority that would oversee its activities, leaving enough room for new partnerships to emerge and new residual by-products to be used as raw materials time and again.

At the moment, as Figure 2 shows, the Kalundborg eco-industrial park comprises a cluster of industrial giants including Dong Asneas Power plant (which is at the centre of the exchange cycle), Statoil refinery, Novo Nordisk (the world’s leading producer of insulin), Gyproc A/S (a construction company which mainly manufactures plasterboards), Novozymes (one of the largest producer of industrial enzymes), Kalundborg municipality and other regional players like farmers or small waste management companies. The exchanges in input and output resources usually take place under the following scenario:

  1. The excess steam from the Asnaes Power Plant is transferred to Kalundborg's heat station and sold to both Statoil and Novo Nordisk which use it as an incoming heat source for their refinery and production lines processes.
  2. The treated wastewater from Statoil is exported back to the Asnaes Plant as cooling water or condensed steam.
  3. At the same time, Gyproc receives industrial plaster from the Asnaes Plant which is used as feedstock for producing plasterboards. It also receives excess gas as an input energy source from Statoil.
  4. The by-product of the yeast fermentation process that is being used for insulin production at Novo Nordisk is sold as fertilizer to local farmers or is converted into yeast slurry, which later is used in animals feed mixes.

Thereby, the Kalundborg Symbiosis participants swap residual materials for mutual benefit, on the premise that the output products from one enterprise can be used as cheap inputs by another company.
It is worth mentioning that in order for the industrial synergy to occur, a close proximity of the partner companies is required, which keeps the park’s infrastructure costs down and makes the realization of cooperation agreements achievable in short periods of time.

In conclusion, by referring to Côté and Hall (1995), it can be stated that through the application of the Kalundborg’s symbiosis model the involved businesses and the local authorities will:

  • Rationalise the use of natural and financial resources
  • Reduce production, material, energy, insurance and treatment costs and liabilities
  • Improve operating efficiency, quality, population health and public image
  • Generate potential income through the sale of waste materials.


Stefan Gulipac is online communication assistant at


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