EU-Backed Circular Economy Project Transforms 12,000 Tonnes of Mussel By-Products into Renewable Energy and Fertilizer

A groundbreaking project in Brittany, France, is converting undersized mussels—previously discarded as waste—into valuable green energy through methanisation (anaerobic digestion). Supported by the European Union (EU), this initiative not only tackles a persistent waste problem for mussel farmers but also fuels the region’s commitment to a circular economy and sustainable energy production.

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Turning a Long-Term Problem into Power

Mussel farmers along the Brittany coast have long struggled with managing a significant portion of their catch: 6,000 to 12,000 tonnes annually of young, undersized mussels, representing up to 20% of their yearly harvest. These smaller shellfish do not qualify for high-value labels, such as those with protected designation of origin.

Historically, this by-product was often dumped back into the sea, causing environmental harm, or left to decompose. However, new environmental regulations are pressing the industry to adopt fully traceable waste valorization chains by 2025–2026.

Exterior view of the industrial prototype ©Jean-Marie Grosmaitre

The pioneering solution is biological fermentation. This process uses microorganisms to break down the mussel waste into a liquid component called hydrolysate, which is then used to generate methane gas, a clean and renewable energy source.

• Shell Valorization: The non-organic shells are also repurposed, creating a closed-loop system by being crushed for use as agricultural fertilizer or animal feed.

Mobile Units Boost Local Sustainability

To maximize efficiency and environmental benefit, the project, developed by mussel producers and researchers like Cultimer, utilizes a mobile processing unit. This unit can be deployed directly on mussel farms, eliminating the need for long-distance transport of heavy, wet organic waste.

Technical room industrial prototype ©Jean-Marie Grosmaitre

Jean-Marie Grosmaitre, Site Director at Cultimer, emphasized the logistical gain: “We don't want to travel 1km for 1kg of mussels, so the aim is to integrate this new practice into the profession’s practices.” By processing waste locally, the project significantly reduces transportation costs and carbon emissions.

The initiative has secured crucial funding from the European Maritime and Fisheries Fund (EMFF) and regional programs, allowing for the rapid development of the technology.

A Win-Win Model for Economy and Environment

This circular model offers multiple benefits that extend beyond the mussel industry:

• Environmental Impact: It prevents organic by-products from polluting the marine environment.

• Economic Viability: It turns a cost-heavy waste stream into two valuable products: clean energy and agricultural resources.

• Community Potential: The project is already attracting wider interest. Grosmaitre noted, “We've been approached by local authorities to recover household and catering waste of meat origin. So, there's a real potential for development on a much wider scale than just mussel farming.”

This innovative solution is poised to transform waste management for the aquaculture sector, contributing directly to Europe's green energy transition and setting a new global standard for resource recovery in coastal economies.