Wild blue mussels, Mytilus edulis.
Photo: Adobe Stock.
In Brittany, north-west France, an innovative project is converting undersized mussels, once treated as waste, into renewable energy through a process known as methanisation.
According to the European Commission’s Directorate-General for Maritime Affairs and Fisheries, the initiative is helping to promote sustainable aquaculture, lower transport emissions and support local waste management.
Each year, up to 20% of the region’s mussel harvest, or between 6,000 and 12,000 tonnes, consists of small mussels that fail to meet market standards for high-value produce such as those with protected designations of origin. These shellfish were often discarded at sea or left to decompose, practices that authorities say caused environmental damage. Pressure from regulators has led the sector to adopt fully traceable waste-recycling systems by 2025–2026.
The new approach uses biological fermentation to break down organic matter and produce methane as "a clean, renewable energy source". The project is also exploring the re-use of mussel shells as agricultural fertiliser or as an ingredient for animal feed, creating what organisers describe as a circular, low-waste production system.
Exterior view of the mobile processing unit used in the project.
To make the process more efficient, producers and researchers have jointly developed a mobile processing unit that can operate directly on mussel farms.
“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,” said Jean-Marie Grosmaitre, Site Director at shellfish producers association Cultimer, one of the project partners, via a news release.
According to the project team, the system benefits both farmers and local communities by reducing marine pollution, generating renewable energy from the hydrolysate produced during methanisation, and creating valuable by-products for agriculture. Grosmaitre added that there is “real potential for development on a much wider scale than just mussel farming”, with interest from local authorities in processing other forms of organic waste.
Funding from the European Maritime and Fisheries Fund and regional programmes has supported the development of the technology and preparation of a prototype for wider use. The initiative, backed by the EU, is being presented as a model for sustainable aquaculture and circular economy practices in Europe’s coastal regions.