Environmental law: focus on agricultural methanization, through the example of a recent administrative dispute
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The implementation of the National Low-Carbon Strategy (SNBC) requires all sectors of activity to develop renewable production, and in particular energy produced from agricultural and forest biomass (wood fuel, methanization, biofuels, etc.).
Agricultural methanization projects are part of this strategy by allowing the production of renewable gas, of non-fossil origin, at the scale of an agricultural farm. Technically, such a methanization unit integrates non-hazardous waste and raw vegetable matter from the farm into an anaerobic digestion process (without oxygen) that produces gas.
The legal framework applicable to such renewable energy production projects comes mainly from the Environmental Code, which sets out the conditions under which a methanization unit can be created and operated.
Through the examination of two recent court decisions of the Administrative Court of Nantes, concerning the building permit and the ICPE operating order for an agricultural methanization unit, this focus sheds light on three important legal points for the promoters of this type of project:
- How to assess the need to switch from the ICPE registration regime to environmental authorization or not?
- What is the relationship between the authorization to create a methanization unit and the pipeline connecting to the public gas network?
- What are the consequences of the specific litigation rules applicable to the authorizations of a renewable energy production installation?
Source:
TA Nantes, July 8, 2025, No. 2413916: https://www.doctrine.fr/d/TA/Nantes/2025/TA32DE21801D6F3BD10327
TA Nantes, Sep 23, 2025, No. 2418353: https://www.doctrine.fr/d/TA/Nantes/2025/TA24CE5BEAB95FE07A023B
1. How to assess the need to switch from the ICPE registration regime to environmental authorization or not?
As a reminder, the Environmental Code provides for three administrative regimes applicable to installations classified for the protection of the environment (ICPE): that of prior declaration, registration (simplified authorization) and that of environmental authorization.
The applicable regime depends on the exceeding of thresholds fixed by a nomenclature established by decree.
An agricultural waste methanization plant falls under heading 2781 of this ICPE nomenclature and the regulatory thresholds depend on the daily quantity of material that can be treated:
Article L.512-7-2 of the Environmental Code provides that an ICPE subject to the registration regime is, in principle, exempt from a prior environmental assessment and that it is the responsibility of the prefect receiving the request to examine the file in order to assess whether the project should be subject to the environmental authorization regime and thus be subject to an environmental assessment.
This examination is based on the location of the project and on the environmental sensitivity of the area of establishment and on the other criteria mentioned in Annex III of European Directive 2011/92/EU relating in particular to the characteristics of the project and to the types and characteristics of its potential impact on the environment.
In the judgment of September 23, 2025, the Administrative Court of Nantes was seized of an appeal against the prefectural decree registering the methanization unit, issued under the legislation on classified installations.
The judgment is interesting concerning the analysis of criteria relating to the examination of retention under the registration regime.
On the one hand, fairly classically in law, the Administrative Court ruled that methanization plants themselves were not envisaged in a sensitive sector, namely that:
- the project plans to treat a maximum of 51 tons of waste per day, i.e. a quantity well below the threshold of 100 tons set by heading 2781-2-b of the ICPE nomenclature for an application for registration.
- The base ground of the project Is found “more than one kilometer from the nearest natural area of ecological, faunistic and floral interest, and is located neither in a wetland nor in a protected perimeter of a drinking water catchment, is part of a vast agricultural area, whose natural environment is not subject to particular landscape or ecological protection”.
- its dimensions remain consistent with comparable installations and the unit is located on the seat of an agricultural holding on land that is not subject to any protection.
On the other hand, the analysis of the digestate application plan (post-methanization organic residues) is more interesting since the judgment commented took into account the characteristics of the farmers' project quite precisely, in order to confirm that the ICPE registration regime was indeed relevant and applicable.
The particularity of this plan for spreading digestate on agricultural land is that part of the plots is located in the drinking water catchment area (AAC) and a quarter of the land in the zone of reinforced action, i.e. already identified as degraded by pollution linked to nitrates.
The environmental sensitivity of this catchment area was therefore analyzed by the Tribunal, which considered that:
- the agricultural operator is already authorized, by a previous prefectural decree, to spread the effluents of his livestock activity in this feeding and catchment area.
- the digestate resulting from methanization will be applied to these plots in place of livestock effluents and chemical fertilizers currently used.
- the change in crop rotation (i.e. cultivated plants) and fertilization practices, which results from the plan for spreading the digestate produced thanks to the methanization unit, will allow:
- to reduce the use of mineral fertilizers by 92%
- to reduce total fertilization by 30% with a decrease in total nitrogen supply,
- as well as a significant reduction (40%) in phytosanitary treatments in the feeding and catchment areas
- wetlands are excluded from the application area
- the petitioner undertakes to adapt its practices to achieve the objectives of the action program relating to this priority capture, in particular on the use of nitrates and phytosanitary products, and to respect the recommendations of the drinking water catchment management union, which issued a favorable opinion on the project
- In addition, the registration order contains specific requirements requiring that digestate be analyzed twice a year, three weeks before each spreading campaign, during the first three years of operation of the unit.
Based on this analysis, and as the operator argued, the Tribunal considered that the ICPE registration regime was adequate for its methanization plant and its application plan.
Source:
TA Nantes, September 23, 2025, n° 2418353: https://www.doctrine.fr/d/TA/Nantes/2025/TA24CE5BEAB95FE07A023B
2. What is the relationship between the authorization to create a methanization unit and the pipeline connecting to the public gas network?
Projects subject to impact studies are defined in the nomenclature annexed to article R.122-2 of the Environmental Code. It defines which projects must be subject to an environmental assessment, either systematically or after analysis by the Administration on a “case-by-case” basis.
A classified installation subject to registration is, in principle, exempt from environmental assessment.
As part of the litigation proceedings, the third party applicants maintained that the methanization unit should have been subject to an environmental assessment since it would involve the establishment of a connection to the gas network over several kilometers, which would constitute a project likely to impact waterways and afforestations.
The question asked is that of the applicability, in the context of a methanization unit, of heading 37 of the “impact study” nomenclature, which concerns the category of projects” pipelines for transporting flammable, noxious or toxic gases, and carbon dioxide for geological storage ”.
To our knowledge, this question was unprecedented in a judgment on the merits.
The Nantes Administrative Court rejected the plea put forward and ruled :
“that the biomethane will be injected into the GRDF network via an injection station, owned by GRDF, located on the private domain of the company Energie 2 L'Eveil, with direct access from the public domain, and, on the other hand, that the pipe that will connect the methanization unit to the distribution network built and operated by GRDF is a distribution pipe, and not a gas transport pipe within the meaning of the provisions of Article L.554-6 of the abovementioned Environmental Code.
Consequently, the connection of the methanization unit to the GRDF network is not subject to compliance with the provisions of section 37 of the nomenclature annexed to article R. 122-2 of the Environmental Code and does not require the carrying out of an environmental assessment.
In addition, and in any event, the construction of this pipeline falls solely within the competence of the gas distribution network operator, and does not need to be described by the petitioner in the registration file for the methanization unit.”
To be precise in law, the Tribunal relied on Article L. 554-6 of the Environmental Code, which provides:
” a transport pipeline delivers liquid or gaseous products to distribution networks, other transport pipes, industrial or commercial enterprises or storage or loading sites.
A distribution pipe is a pipe, other than a transport pipe, serving one or more users or connecting a biomethane production unit to the distribution network. Pipelines connecting a biomethane production unit to the transport network are subject to the provisions of this code applicable to distribution pipes, provided they comply with the characteristics and conditions mentioned in article L.554-5 fixed for such pipes, as well as to the provisions of section 4 of Chapter V of this title.”
This division between the two procedures is an important legal clarification and is very useful for project leaders for a methanization unit, the design offices that support them and the State services responsible for examining these requests.
3. What are the consequences of the specific litigation rules applicable to the authorizations of a renewable energy production installation?
As part of the contestation of the permit to build the agricultural methanization unit, which authorizes the construction of manure storage buildings, the digester and the post-digester, the Administrative Court examined a procedural point applicable specifically to renewable energy production installations.
This is article R.311-6 of the Code of Administrative Justice, resulting from Decree No. 22-1379 of October 29, 2022 relating to the legal regime applicable to the litigation of decisions relating to installations for the production of energy from renewable sources.
In order to speed up the processing of disputes, this temporary arrangement provides for an exceptional litigation regime in respect of the following aspects:
- the two-month appeal period cannot be extended by administrative appeal (ex gratia appeal), which is an exception to the general rule applicable in this area
- and the court must rule within a maximum of 10 months, failing which the dispute is brought directly before the Administrative Court of Appeal, which is an exception to the rules of administrative litigation, which do not set a deadline for adjudication.
The projects covered by this regime include:
- installations for the methanization of non-hazardous waste or raw vegetable matter,
- photovoltaic production installations with a capacity exceeding 5 MW,
- geothermal deposits, hydroelectric installations of 3 MW and more.
This system applies to the operating permit issued under the Environmental Code, but also to the corresponding urban planning authorization as well as to the other administrative procedures necessary for the project.
This may include, among other things, a declaration under the “Water Law”, archaeological prescriptions, a permit to occupy public land, an authorization to clear land, etc.
This contentious regime provided for in article R.311-6 of the Code of Administrative Justice applies to the construction permit issued for the construction of an agricultural methanization unit on the farm.
In this sense, the judgment rendered by the Administrative Tribunal of Nantes ruled that it resulted from:
“The combination of these provisions and the period for litigation against a building permit issued for a plant for the methanization of non-hazardous waste or raw vegetable matter is two months. It starts as soon as a sign containing the information mentioned in particular in articles A. 424-16 and A. 424-17 of the Urban Planning Code is displayed on the site. ”.
“The fact that the Prefect acknowledged receipt of the free appeal filed by the applicants on 14 May 2024, without mentioning the remedies and time limits for appeal, does not affect the applicable litigation period, since, as indicated in point 6, this administrative appeal did not extend the time limit for litigation.”.
As a result, the regulatory posting of the building permit carried out on site for two months — which had been noted three times by a Commissioner of Justice — makes it possible to “the period for litigation, which is in the nature of a clear deadline, began to run on Friday, April 19, 2024, and expired on Thursday, June 20, 2024, without the ex gratia appeal filed on May 14, 2024 having been such as to interrupt it”.
As a result, the Tribunal dismissed the third parties' request registered on September 10, 2024 as being late, that is, filed after the regulatory deadline.
The building permit is then legally purged of the recourse of third parties.
TA Nantes, 1st ch., July 8, 2025, No. 2413916: https://www.doctrine.fr/d/TA/Nantes/2025/TA32DE21801D6F3BD10327
Like this contentious example relating to the development of a methanization unit, the law of classified installations embraces substantive and procedural legal and technical issues that require specific legal support for project developers, as early as possible in the development of the project, but also, sometimes, before the courts.
Lawyer specialized in environmental law
Partner at SQUAIR
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