Following a call for expressions of interest, 24 hydrothermal gasification projects were selected, the majority in industry. State support is expected in order to bring about the emergence of this sector which could transform a lot of waste into renewable gas.
Among the challenges to be met for a successful energy transition, the production of methane from renewable sources is not the least. The gas vector remains essential for certain uses in industrial processes and can maintain or take on new interest in buildings (heating and cooking), mobility (bioNGV vehicles) and electricity production (peak power plants in a 100% renewable electricity system). Its decarbonization is therefore essential.
The anaerobic digestion of organic waste is the main way today to supply the network with gas from renewable sources: at the end of November, 720 anaerobic digestion sites had an injection capacity of 13.2 GWh/year. If this technology continues to develop significantly, it should be followed by two of its cousins: pyrogasification and hydrothermal gasification. The latter has just been the subject of a call for expressions of interest (AMI) during which 24 projects were submitted.
“This is a first in France, which should make it possible to bring together as many stakeholders as possible, to demonstrate that hydrothermal gasification concerns a wide variety of sectors and inputs, and to give French developers the opportunity to gain maturity. in order to ensure the industrial deployment of this technology”summarizes Robert Muhlke, hydrothermal gasification project director at GRTgaz.
Technological advantages to be confirmed
The AMI was supported by the “New Energy Systems” sector strategic committee and its management was entrusted to GRTgaz, manager of the gas transport network. He is also the leader of the national working group on hydrothermal gasification which initiated and proposed the idea of the AMI at the end of 2023.
The dynamics revealed by this AMI are encouraging. Three major sectors of activity were present in ten different regions:
- farmers/methanizers who can thus recycle waste with low methanogenic power in a different way and avoid having unsuitable digestates or in too large a quantity in relation to spreading rules;
- urban waste managers (public and private) who would reduce the impact of the treatment of numerous wastes including wastewater treatment plant sludge and could recover residues potentially recoverable into co-products (water, energy, nutrients) for their territory;
- industrialists, particularly in the agri-food and chemical sectors, who would find there an outlet for complex waste, while reducing the cost of their treatment and the associated greenhouse gas emissions, by recovering energy, and reducing impacts on the environment. The quantity of final waste would also decrease, with this alternative technology to incineration or landfilling.
Among the winners, nineteen projects are of industrial size in the preliminary phase and would process a total of 1.11 million tonnes of raw material per year. This would give them a methane injection capacity of 1,900 GWh/year. It should be noted that two of these projects exceed 200 GWh/year. Five other projects, of industrial size in an advanced phase, total 130,000 tonnes of raw material per year for a total of 90 GWh/year. There are also two industrial demonstration projects, of smaller size (maximum 4,000 tonnes of raw material per year each).
The total waste to be used for these projects represents 400,000 tonnes of dry matter per year. Half comes from the agri-food industry (vinasse, grape marc, wheat residue, etc.), a small quarter from the chemical industry (heavy distillation, industrial sludge, etc.) and the rest is distributed roughly in equal parts between digestate and agricultural residues, sludge from sewage treatment plants and urban waste (fat, pulp, glycerin, bio-waste, etc.). 73% of all this waste is of biogenic origin.
Ensure public support for projects
“If the projects are to be an opportunity to establish the economic model of hydrothermal gasification, they are above all necessary to show all the benefits of this solution. It is in fact only from a certain size of installation that we avoid the effects of clogging in the pipes, and that we concentrate the inputs more in order to increase the share of carbon which will be used. to generate much more injectable gas at the output” explains Robert Muhlke.
As a reminder, two families of processes exist in hydrothermal gasification at comparable high pressures (250 to 300 bars). The first operates at high temperature (around 600 to 650°C), the second integrates catalysis lowering the temperature (400 to 450°C) and accelerating the reaction time. As water is the essential reagent, both have the advantage of being able to treat waste with a high water content. They also make it possible to mix different types of waste, to precipitate and evacuate the inorganic part of the waste (phosphorus, potassium and metals) upstream of the gasifier, and to recover water and nitrogen downstream of the process. And of course have a synthetic gas which, once treated, provides synthetic methane and CO2 residual of high purity.
How can we ensure that the 24 AMI projects will succeed? “We are entering a discussion phase with state services so that financial support can be provided to them through experimental contracts. This would allow a slightly longer learning period so that farmers can properly test the technology with their specific input. Regulatory aspects must also be addressed, as no current ICPE section integrates thermochemical conversion processes”explains Robert Muhlke.
Support from 2025 would allow demonstration projects by French developers to come to fruition by the end of 2026 and to optimize their operation by 2028. Industrial deployments from 2027/2028, also integrating Dutch, Swiss and Spanish, would pave the way for the production trajectory projected by the sector: 2 TWh per year of renewable gas by 2030, 12 TWh by 2035 and at least 50 TWh by 2040/2050.
