The Challenge

Sotenäs is a small coastal municipality in Sweden with around 9,000 inhabitants. Fishing is its economic backbone, home to the country’s second largest fish auction as well as three of Sweden’s major seafood processing plants (Marthinson, 2022).

By 2010, decades of rapid expansion had created serious sustainability challenges. Environmental regulations prohibited companies from increasing their discharges of processed water into the sea, and each year more than 15,000 tonnes of sludge and fish trimmings had to be transported to distant biogas plants in Norway, Denmark, and Sweden. These long and costly transports resulted in substantial CO₂ emissions entering the atmosphere. Under pressure, some businesses considered relocating, a move that would have put the local economy at risk (Marthinson, 2022).

The Circular Solution

In response, the Sotenäs municipality launched the Sotenäs Centre for Symbiosis (Symbioscentrum) in 2015. The centre functions as a hub for industrial symbiosis (IS), bringing together the municipality, a local college, a Swedish state-owned venture capital company Fouriertransform, and six other partner organisations (Charter & Whitehead, 2023).

The vision of Symbioscentrum is both economic and environmental: to create jobs, develop value-added products, and achieve greater efficiency by linking industries and upcycling local waste streams. Its collaborations extend across sectors such as food production, aquaculture, renewable energy, algae production, and marine technology (Charter & Whitehead, 2023).

At the outset, three core projects anchored the system:

·         a biogas facility to process fish trimmings,

·         a wastewater treatment plant, and

·         the recycling of ocean plastics and fishing gear.

Today, fishing companies send their waste to the Renahav biogas plant, which produces renewable energy and hot water that are supplied back to those same companies. The facility also generates digestate — a nutrient-rich by-product of anaerobic digestion — which local farms use as organic fertiliser. Over time, new businesses joined the loop. For instance, the microbrewery Smögen Ale AB delivers spent malt to the biogas plant, further demonstrating how waste streams can be repurposed into resources (Giacometti et al., 2023; Trokanas et al., 2014).

Climate Impact

This model has yielded both business and environmental gains. An environmental impact assessment in 2018 estimated:

·         reductions of approximately 60,000 tonnes of CO₂-eq emissions,

·         a decrease of 388 tonnes of phosphate-equivalent eutrophication impacts,

·         avoidance of more than 19 million tonne-kms of waste transport, and

·         the creation of local green jobs.

Additionally, by extracting nutrients from wastewater, the initiative helps improve aquatic conditions and enhances the quality of marine resources, especially fish. Streamlined operations also reduce energy and logistics costs, making participation economically attractive for local companies (Martin & Carlsson, 2018).

Replicability

The Sotenäs case shows how municipalities can use industrial symbiosis principles to manage environmental pressures while strengthening the local economy. The European Union hosts more than 6,600 industrial facilities and up to 43 million potential synergies for IS — meaning there is vast untapped potential across Europe (Quintana, Chamkhi, & Bredimas, 2020).

Drawing on this experience, Symbioscentrum recommends five enablers for successful symbiosis: 

• Networking – the human element is key

• Innovation – Access to funding, knowledge and testing are highly beneficial

• Smart adaptation – the business model needs to be viable

• Physical proximity – can be crucial for communication and resource exchange

• Storytelling – A powerful tool to communicate your vision and attract new participants

(Giacometti et al., 2023).

The initiative also looked to the well-known Kalundborg Symbiosis in Denmark as inspiration, the world’s first IS network, which now involves 17 public and private organisations and more than 30 different resource flows (Giacometti et al., 2023).