24 Feb 2025
The building industry produces 40% of all waste in Australia – but what if there was a way to turn one company’s waste, into something of value for another?
Since 1972, a unique industrial community in Kalundborg, Denmark, has been working together to do exactly that, sharing excess energy, water, and materials, so that far less goes to waste. It is known as Kalundborg Symbiosis, and today it’s made up of 17 public and private companies that are physically connected, with one company’s surplus of resources becoming a valuable product to another.
It is a stunning example of a circular system, where instead of the linear take-make-waste economy, companies collaborate to share inputs and outputs.
To date, over 30 different streams of excess resources continue to move between the companies in Kalundborg, creating a symbiosis of resource exchange, adding more resilience and profit to the partners.
For example, the steam used in pharmaceutical production is generated by a power plant that utilises cooling water from the oil refinery as both a water and heat source. When industrial wastewater is treated at the nearby utility, heat is extracted and repurposed for district heating, benefiting local citizens in Kalundborg.
The result?
Each company in the Symbiosis can reduce their impact on the environment and decrease dependence on raw materials. But innovation of this scale also lends itself to economic growth and job creation, as what was once discarded becomes a valuable resource.
To give you a taste of what to expect from her international keynote speech at TRANSFORM 2025, we spoke to Mette Wendel, Symbiosis Facilitator at Kalundborg Symbiosis, about this phenomenal example of circularity in action.
Firstly, I would love to know how you got to where you are in your career. What drew you to circularity, particularly your work in the Kalundborg Symbiosis?
What led me to Kalundborg Symbiosis is a personal passion for the green transition and environmental care. Within this partnership, I feel I have the opportunity to drive change toward a more sustainable future. It is my dream job—just as meaningful and full of inspiring challenges as I could have ever hoped for.
Working with industrial symbiosis wasn’t always the plan; my background is in teaching, with science as one of my subjects. After 20 wonderful years in education, I transitioned into project management, gaining experience in the field of green transition. Three years ago, I joined the Kalundborg Symbiosis Administration.
Kalundborg Symbiosis is an incredible example of a mutualistic relationship. Could you give us an insight into what this looks like?
The members of the partnership contribute significantly to the collaboration. They engage in various forums where they share challenges and future plans, explore new potential resource streams, identify synergies, and assess opportunities for co-investments and new projects, such as infrastructure development. This work is facilitated by my colleagues and me in the Kalundborg Symbiosis Administration.
We say that our partnership is built on five core values: trust, confidentiality, openness, equality, and cooperation.
How important is communication in Kalundborg Symbiosis, and in broader efforts to implement a circular economy?
Communication is key! The former chairman of Kalundborg Symbiosis used to say that the three most important things in an industrial symbiosis cooperation are: communication, communication, and communication.
We recognize communication as a crucial tool for spreading awareness of industrial symbiosis—not only to stakeholders in Denmark but also globally. Learning about real-life cases, with their significant environmental and financial benefits, sparks curiosity about how things work. Ideally, this curiosity leads to envisioning how industrial symbiosis could be implemented in different contexts. In my opinion, this also applies to the adoption of circular economy principles and the extension of value chains in production.
Within the partnership, communication is just as important. As mentioned above, keeping your partners informed about both your future plans and your challenges allows them to support you in overcoming obstacles. Instead of viewing complex problems as the responsibility of a single company, we see them as shared challenges. Our approach is to tackle them together.
How does a symbiotic alliance nurture, not only environmental sustainability but economic prosperity?
In Kalundborg, we have seen firsthand how collaborative resource sharing and waste exchange can lead to significant cost savings for participating companies by reducing procurement costs and waste disposal expenses. A small but important note: we no longer refer to it as waste – we call it residuals to shift perceptions and highlight its value.
Additionally, industrial symbiosis enhances efficiency, which is also good business. By sharing resources such as energy, water, and materials, industrial symbiosis optimizes resource use, minimises waste, and improves overall operational efficiency.
Finally, industrial symbiosis fosters resilience, risk mitigation, and competitive advantages – all of which contribute to higher profits and long-term business security. By diversifying resource supply chains and reducing dependence on single sources, industrial symbiosis strengthens resilience against disruptions such as supply chain failures or resource shortages. Moreover, participation in industrial symbiosis initiatives can boost a company's reputation and appeal to customers, investors, and regulators by demonstrating a commitment to sustainability and responsible resource management.
Do you envisage the expansion of Kalundborg Symbiosis, and have you seen this replicated elsewhere?
In recent years, Kalundborg Symbiosis has expanded, evolving from a long-standing group of partners—many of whom had been involved since its inception 53 years ago—into a dynamic partnership that continues to welcome new members. These include companies choosing to establish themselves in Kalundborg to connect with the symbiosis’ resource streams, as well as existing companies recognizing the partnership’s potential in terms of ESG benefits and reputation.
We see industrial symbiosis being replicated all around the world. In Denmark, there are several initiatives; they have joined forces to inspire each other and develop further under the umbrella Symbiosis Network Denmark. In Kwinana, Australia, a symbiosis initiative focuses primarily on water, and similar developments are emerging globally. Currently, we are working in Rio de Janeiro, Brazil, and Washington State, USA, and we are about to start a project in Kenya. In all these locations, local, enthusiastic partnerships are driving the change forward.
Can’t wait to learn more and hear more about the insights gained from 53 years of industrial symbiosis? You can catch Mette Wendel at Transform 2025 on day two in Sydney, where she will be taking the main stage for the International Keynote: Circular production in action through industrial symbiosis.