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Industrial symbiosis

Air pollution from industry production

Air pollution in agriculture


The worlds first industrial symbiosis: from waste stream to resource current

8. September 2023

Solution provider

Kalundborg Symbiosis

Kalundborg Symbiosis is a partnership between sixteen public and private companies in Kalundborg. The main principle is that a waste stream in one company becomes a resource in another, benefiting both the environment and the economy.

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It takes about 1.5 years to replace what we use and consume in one year. This requires a new way of thinking and a new economic model – one which encourages the use of circular business models and reuse of resources. This is exactly what the symbiosis model strives to do. With a main aim to reuse resources in a mutually beneficial way, reducing consumption and saving money, an industrial symbiosis is a partnership between different industries and business to share resources, such as materials, energy, water, and expertise.


Developed back in 1972, Kalundborg Symbiosis was the first industrial symbiosis in the world. With its circular approach to production, Kalundborg Symbiosis remains as one of the world’s leading industrial symbioses and is today a partnership between sixteen public and private companies in the municipality of Kalundborg in Denmark. The project facilitates an opportunity for the companies to synergistically leverage each other’s residual and byproducts, sharing and reusing resources, thus making savings and minimizing waste.

The collaborative approach bolsters production without imposing additional strains on energy, water, or natural resources. For example, biotech companies such as Novozymes and Novo Nordisk contribute with their residual biomass to Kalundborg Bioenergy, a biogas plant owned and operated by Bigadan. Here, biogas is produced and upgraded to natural gas quality through a refining process where carbon dioxide and hydrogen sulphide are removed from the product. Biomethane is sent to local companies, Gyproc, Unibio and Kalundborg Refinery, and to end consumers via the national gas grid. Sulphur from the hydrogen sulphide fraction is collected and reused in fertilizer products together with the gasified biomass residual. In conclusion, the symbiosis turns one company’s waste into a steady resource flow for another, benefiting both the environment and the economy.

Biomass from Kalundborg Symbiosis

Photo credit: Kalundborg Symbiosis


Kalundborg Symbiosis is a perfect demonstration of circular economy: residue is used for energy production  in a local set-up, saving transportation costs on both biomass (supply) and fertiliser (output) over long distances.

The cooperation ensures local companies obtain a green energy supply at the same time as resources are being used, shared, and saved in a sustainable way. The Kalundborg Symbiosis is a great example of a circular business model, creating growth in the local community, while supporting the green transition.

Facts: Kalundborg Symbiosis

Every year, the symbiosis saves partners and the environment:

  • 62.000 tonnes of residual materials which are recycled.
  • 4 million m3 of groundwater by using surface water instead.
  • 586.000 tonnes of CO2 emissions.
  • 80 percent of the CO2 emissions in the Symbiosis have been reduced since 2015.
  •  The local energy supply is now CO2-neutral.
Learn more about Kalundborg Symbiosis