Germany is known for its NAWARO fermenters. This acronym stands for NachWachsende Rohrstoffen, and it refers to first generation products. Raw materials include silage maize, sugar beets and grass, which should be free from any kind of treatment or processing. A list of positive residual products that may be processed has been compiled. The products must be pure vegetal residual products, for which a standard gas yield has been calculated. If such a residual product is processed in a NAWARO fermenter, then the standard gas yield of this product needs to be subtracted in order to calculate the remunerations for green gas or green electricity. Some examples of such positive residual products are cereal residues, plant-based glycerine, potato peels, and others. Using these types of biomass in biogas plants is defined in the municipal permit for the site in question. If the fermenter wishes to adjust its recipe, then it must resubmit the recipe to the local authority for its approval. Besides the NAWARO fermenters, there are also industrial fermenters in Germany. These companies help municipal authorities and/or businesses to dispose of their organic waste. This mainly consists of kitchen waste, industrial food waste, and/or garden waste.

For non-industrial fermenters (of which there are just a few in Denmark), at least 75% of the biomass (formulated as kilograms of dry matter) must be of agrarian origin. This means animal manure on the one hand, and vegetal residues from the processing of crops or crop residues sourced directly from the land, on the other. For energy crops, Denmark sets an upper limit on how much can be processed, and silage maize may no longer be fermented starting in 2025. The remaining 25% of the kilograms of dry matter can be industrial biomass. Using these types of biomass in biogas plants is defined in the municipal permit for the site in question. The permit states how much biomass per category may be processed, for instance animal manure, slaughterhouse waste, and so on. Finally, limits are imposed on the composition of the digestate, which again has an effect on the biomass.

In France, biogas and biomethane plants operate under the ICPE framework (Installations Classées pour la Protection de l’Environnement). The ICPE permit defines both the types of biomass that may be processed and the maximum annual volumes, based on the environmental and sanitary risks associated with the installation. Anaerobic digestion plants generally fall under ICPE rubric 2781, which covers the treatment of non‑hazardous waste by anaerobic digestion and establishes operating conditions, monitoring requirements and thresholds depending on plant size and throughput.

For larger installations—those with a capacity of 2 MW or more or an average production of over 200 Nm³ of methane per hour—RED III sustainability certification is mandatory. Operators must demonstrate full traceability and sustainability of all biomass inputs, including agricultural residues and authorised CIVE crops (intermediate energy crops), in order for the produced biomethane to be recognised as renewable and eligible for support schemes.

In the Italian biogas and biomethane sector, a distinction is made based on the type of feedstock processed by anaerobic digestion plants. In practice, this results in two main categories: plants processing organic waste and plants based on agricultural biomass. Plants treating organic waste typically process the organic fraction of municipal solid waste and biodegradable industrial waste and operate under waste management regulations. Agricultural plants are authorised to process so‑called agricultural matrices, including animal manure, agricultural residues and selected co‑products from the agri‑food industry. Under the current regulatory framework, the use of sustainable waste and residue streams is strongly prioritised, while the use of dedicated energy crops is restricted. When applying for a permit to build a new plant or to convert an existing biogas plant to biomethane production, the operator must submit a detailed feedstock composition specifying the types and annual volumes of biomass to be processed. This feedstock mix is assessed and approved by the competent local authority and forms part of the operating permit. If the operator intends to change the approved feedstock composition, a new approval is required. This permitting approach ensures control over environmental impacts, compliance with sustainability criteria and the quality and safe use of the resulting digestate.