SUEZ and SIAAP Launch France’s Largest Urban Biogas Plant at Seine Aval to Support Renewable Energy Goals

SUEZ and SIAAP have inaugurated a cutting-edge biogas production unit at the Seine Aval wastewater treatment plant, located in the Yvelines department of the Île-de-France region. This newly operational facility is now among the largest of its kind in Europe, with the capacity to generate 40 gigawatt-hours of biomethane annually. The clean energy produced will be injected into the national gas distribution network and is expected to meet the yearly consumption needs of approximately 10,000 French households.

This milestone aligns with national efforts to accelerate the energy transition and improve energy sovereignty through local, sustainable solutions. The plant processes sewage sludge through anaerobic digestion to recover biogas, which is then upgraded into biomethane suitable for grid injection. The result is a transformation of a traditionally carbon-intensive utility into a valuable contributor to France’s renewable energy mix.

The project stems from the collaboration between SIAAP, which oversees wastewater treatment for nearly nine million people in the Paris region, and SUEZ, a global leader in sustainable infrastructure and resource recovery. The biogas unit represents a bold shift toward integrating circular economy principles into public infrastructure, where waste streams become resources and energy is recovered locally.

Sabine Donadieu, General Manager of SUEZ Treatment Infrastructure France, highlighted the strategic importance of the project by stating:
"This new biogas unit is a concrete demonstration of how innovation in wastewater management can help fight climate change. It contributes to the decarbonization of the energy sector and supports France’s commitment to develop local, low-carbon energy."

Georges Février, President of SIAAP, emphasized the project’s long-term vision and public value:
"At Seine Aval, we are showcasing a sustainable model where water, waste, and energy converge to form a modern utility. This project is the culmination of years of technological advancement and collaboration between public and private sectors to create infrastructure that serves both environmental and societal goals."

This development is not only significant in terms of energy output, but also in what it represents for the future of utility infrastructure. As cities face growing pressure to meet climate targets and decarbonize essential services, integrated models like Seine Aval offer scalable, replicable solutions. The plant also reduces greenhouse gas emissions associated with conventional sludge treatment, enhancing its environmental profile while creating long-term operational value.

The biomethane produced at Seine Aval will feed directly into the GRDF gas network, supporting grid diversification and providing a reliable source of renewable gas to end-users. This effort is a critical step toward building resilient urban systems that produce their own energy from existing resource flows, such as wastewater.

By reimagining what a wastewater treatment plant can achieve, SUEZ and SIAAP are setting a precedent for how infrastructure can be retooled to deliver on multiple fronts—sanitation, energy recovery, emissions reduction, and circular resource use. Their partnership is a blueprint for how utilities worldwide can deliver climate-positive impact through innovation, collaboration, and a forward-thinking approach to infrastructure.

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