Fuelling Europe’s green energy revolution with mussel by-products

In the French region of Brittany, a pioneering project is transforming undersized mussels, once considered waste, into valuable green energy through methanisation. This process produces methane gas, a renewable energy, from organic materials. With the help from the EU, this project supports sustainable practices, local, eco-friendly waste management and reduces transportation costs.

Mussel waste in French mussel farming 

Along the coast of Brittany, mussel farmers have long faced a persistent challenge: up to 20% of their yearly harvest consists of young, undersized mussels, amounting to 6 000 to 12 000 tonnes. These smaller shellfish do not meet the criteria for high-value products such as those eligible for protected designation of origin. 

In the past, they were often discarded back into the sea, causing environmental harm, or left to rot. However, rising pressure from environmental authorities is pushing the sector towards fully traceable valorisation chains and away from open-air disposal by 2025–2026.

Turning a problem into power

One of these industrial valorisation processes is biological fermentation, where microorganisms break mussel waste down into smaller units (hydrolysate) that can be used to generate methane, a clean, renewable energy source. 

Additionally, mussel shells can be repurposed as agricultural fertiliser or animal feed, creating a closed-loop system and adding value to materials that would otherwise be discarded.

A vision for circular economy in mussel farming

Inspired by circular‑economy principles, mussel producers, local authorities, and scientific researchers have developed a mobile processing unit that can be deployed directly on mussel farms. This unit allows for the local processing of mussel waste, eliminating the need for costly and environmentally harmful transportation. 

“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” says Jean-Marie Grosmaitre, Site Director at Cultimer.

A win–win for farmers and communities

The project brings advantages to everyone 

• it reduces the environmental impact of mussel farming by preventing by-products from being discarded into the sea
• the hydrolysate produced through methanisation of undersized mussels generate clean energy
• the crushed mussel shells becomes a valuable resource for agriculture, improving the economic viability of mussel farms.

“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.” says Jean-Marie Grosmaitre.

Funding from the European Maritime and Fisheries Fund and regional initiatives has been crucial in developing the technology and preparing the prototype for use across mussel farms in France.

This innovative project is set to transform the way mussel farming handles waste, providing a sustainable solution that benefits both the environment and the economy. 

More information

Website of the project: Cultimer