Kalundborg Symbiosis, a collaborative partnership, located in Kalundborg, Denmark, is a groundbreaking example of industrial symbiosis, where diverse industries collaborate to reuse each other’s by-products, waste, and energy resources in a highly efficient, mutually beneficial system. Initiated in the 1960s, Kalundborg is widely recognized as one of the earliest and most successful implementations of circular economy principles at industrial scale. This cooperation has significantly reduced waste, cut carbon emissions, and optimized energy use, while delivering economic benefits to its participants.
Background and origins
The term “symbiosis,” borrowed from biology, describes a mutually beneficial relationship between different organisms. This concept aptly represents the collaborative ecosystem in Kalundborg, where 16 diverse companies and organizations work together to achieve shared economic and environmental goals.
The Kalundborg Symbiosis emerged organically, driven by the practical need for sustainable solutions to shared challenges rather than centralized planning or government mandates. It has since grown into a highly interconnected network of industrial exchanges, serving as a global model for sustainability.
The first project involved channeling cooling water from Lake Tissø to an oil refinery in 1961. Another milestone came in 1972, when excess gas from the refinery, previously wasted, was redirected to a gypsum board plant to dry its products. Over the years, the network has expanded to include numerous participants, each contributing to and benefiting from the shared resources.
Energy synergies at the core of Kalundborg Symbiosis
At the heart of Kalundborg Symbiosis lies an innovative approach to energy exchange, fostering collaboration and sustainability among industrial partners. Key initiatives include steam and heat sharing, where a defining feature of the system is its network of green pipelines that transport steam from the Asnæs Power Station to various partners. Initially a by-product of electricity generation, steam has evolved into the station’s primary output, with electricity now serving as a secondary product. Recent years have seen a transition from coal to biomass in steam production, further enhancing its sustainability. Companies such as Novo Nordisk and Novonesis utilize the steam for critical processes like cleaning, sterilization, and distillation, while the Asnæs Power Station supplies district heating equivalent to the needs of 24,000 households in the local municipality, with Kalundborg Utility distributing this heating and supplementing it during colder months with a heat pump. Additionally, residual heat from production processes at industries like Novo Nordisk is harnessed to reduce energy demands, maximizing resource efficiency.
Another important initiative is biogas production, where Novo Nordisk’s pharmaceutical processes generate a nutrient-rich by-product known as yeast slurry. This slurry is sent to Kalundborg Bioenergy, where it is gasified and converted into biogas, or biomethane, as well as fertilizers. This process exemplifies the principles of the circular economy by transforming waste into a sustainable energy source, demonstrating the mutual benefits of industrial collaboration.
Kalundborg Symbiosis operates on core principles of industrial symbiosis, including resource efficiency, economic benefits, and environmental sustainability. Resource efficiency involves optimizing the use of raw materials and by-products, while economic benefits are achieved by reducing costs associated with waste disposal and material sourcing. Environmental sustainability is supported by minimizing emissions and waste through closed-loop systems, ensuring a balance between environmental responsibility and economic profitability.
The environmental and economic benefits of Kalundborg Symbiosis are significant. Collaborative energy use reduces the need for additional energy production, cutting CO₂ emissions by hundreds of thousands of tons annually, and by the end of 2025 the Kalundborg CO2 Hub will be actively capturing and storing biogenic CO2.
By redirecting by-products for reuse, landfill contributions are significantly decreased. Shared water systems save millions of liters each year, easing pressure on freshwater resources. Companies involved in the symbiosis benefit from cost savings by reusing by-products and accessing shared energy resources, which lower energy and waste management expenses. Moreover, the symbiotic partnership highlights the commitment of participating companies to sustainability, enhancing their corporate reputation and reinforcing the value of industrial collaboration.
Global influence and legacy
Kalundborg has inspired similar projects worldwide, showcasing how economic gains align with environmental stewardship. It has contributed to global frameworks on industrial ecology, circular economy, and sustainable development, with regions across Europe and beyond adapting its model to local contexts.
The success of Kalundborg underscores the potential of resource-sharing, waste minimization, and energy efficiency as transformative strategies. Though replicating its model may face challenges, its principles remain a blueprint for industries seeking sustainable and economically viable solutions.
