Hydrothermal gasification: NaTran and SUEZ, driving forces behind the French industry

Still little known to the general public, hydrothermal gasification can be used to transform a wide range of urban, industrial and agricultural waste into biomethane or low-carbon gas that can be fed into the grid. It also recovers CO₂ and minerals such as phosphorus, as well as nitrogen and water, which can then be recycled in the agricultural and industrial sectors.

The HG process operates at high pressure and high temperature, in the presence of water in the gasifier. It greatly reduces or eliminates the quantity of final waste and destroys micropollutants and pathogenic organisms.

The call for expressions of interest that NaTran carried out in 2024 confirmed the interest in this innovative sector in France. On this occasion, 24 project developers from the industrial (food and chemicals), urban and agricultural sectors submitted projects, whose cumulative gas production capacity could reach 2 TWh/year by 2030, according to one estimate.

"This is one of SUEZ's most significant investments in research and development," says Bruno Hervet.

In 2021, the Group joined forces with researchers at the Institut de la Chimie de la Matière Condensée de Bordeaux (ICMCB), a CNRS laboratory specialising in supercritical fluids, to develop a unique hydrothermal gasification facility that is now operational.

In January 2023, the first prototype capable of treating 5 litres of effluent per hour was launched in Bordeaux. Given the success of the installation, SUEZ decided to build a full-scale pilot plant this time, at Saint-Selve in Gironde. It will be capable of recovering up to 150 litres per hour of sludge and other waste. A first in France. Commissioning is scheduled for 2026.

"The knowledge acquired during the trial will be used to validate or modify equipment with a view to industrialising a standard solution by 2030," emphasises Bruno Hervet.

Hydrothermal gasification offers a low-carbon energy opportunity for many types of waste. SUEZ's innovation allows us to go even further. "Thanks to our control of the process and the creation of our "GH-LAB", we have extended the scope of our activities to include the recovery of other types of waste. Our global vision of the waste sector enables us to intervene in all areas where current solutions are costly and not very effective," emphasises Bruno Hervet.
 

To reach industrial scale, the sector now needs genuine recognition. This involves simplifying the regulatory conditions and introducing public support mechanisms to encourage, at the very least, the implementation of the first industrial demonstration projects in the regions.

It will be able to count on the support of NaTran, which has contributed to the development of HG in France from the outset. "This is the result of the work that NaTran has been undertaking on hydrothermal gasification since the end of 2018, which expanded in 2020 when a group of 27 partners, including the SUEZ group, formed to launch the National Working Group dedicated to hydrothermal gasification, which will shortly be integrated as a new HG Cluster within the Biogaz Vallée association," says Robert Muhlke, Director of the Hydrothermal Gasification Cluster at Biogaz Vallée and former Product Director for Hydrothermal Gasification at NaTran.

Today, NaTran continues its mission as a leader: regulatory facilitation, dialogue with government departments, technical support, networking, and so on. The aim of our actions is to help a solid, structured industry to emerge and take root in France, in support of the energy transition, industrial decarbonisation and local employment.