Public dossier Questions and the other side
Questions
Short answers to the questions we are asked most, with sources.
What is a biomethane plant?
An industrial installation where bacteria break down organic waste in closed tanks without oxygen. It produces biogas, 50–70% methane, which is upgraded to biomethane for the gas grid; what is left, the digestate, is spread on fields as fertiliser.
Where exactly is it?
In the parish union of Avelãs de Ambom and Rocamondo, between Avelãs de Ambom and Pêra do Moço. The exact parcel has not been published. MOV.AP measured the parcel outline on satellite imagery; on the map its position is approximate.
Who is the promoter?
Lambert Bioenergy (Biometano Cosmos, Unipessoal Lda.). At a council meeting the mayor said he does not know who the owner is. A councillor said the proposal arrived by email from a Spanish company, "Lambert", and that the tax number belongs to another company. The company registry certificate was requested three times; the documents sent to councillors in August are not public.
Has the project already been approved?
No. The Câmara recognised the municipal public interest and the Assembleia Municipal gave a "positive opinion of intent". The mayor called it "a mere intention" and said urban-planning and environmental licensing are still to come. A biomethane plant needs prior registration with DGEG and environmental and planning licences before it can operate.
Will there be an environmental impact study?
It depends on the capacity, which has not been disclosed. An environmental impact assessment is mandatory from 100 t/day, or at any capacity in a sensitive area; below that, the need is assessed case by case.
Will there be a public consultation?
As of 16 October 2026 we had found none on the Participa portal. If there is an environmental impact assessment, the consultation lasts 30 working days and anyone can take part. We will publish the date in the agenda as soon as it is known.
What waste will it treat, and how much?
The only public information is "non-hazardous organic waste". The types, tonnage and origin have not been disclosed.
How many trucks will there be?
It is not known: the number has not been disclosed. At comparable plants in other countries, traffic studies forecast dozens of heavy-vehicle movements a day. The real number has to come from the project's traffic study.
How far away are the homes?
Measured by MOV.AP from the parcel boundary: the water extraction zone known to local residents at 352 m, Quinta Monte Frio at 370 m, the farm to the east at 654 m, the edge of Avelãs de Ambom at 1,038 m and Pêra do Moço church at 1,391 m.
Is there a mandatory minimum distance in Portugal?
We found none. In France it is 200 m from third-party homes; in Castilla-La Mancha a draft decree proposes 2,000 m.
Will it smell?
It depends on the design, the management and the wind. In field inspections, odour from biogas plants was noticed up to 250–600 m away. In Guarda, especially in summer, westerly and north-westerly winds would carry odour east and south-east; in winter they also blow from the north-east and south. The simulator gives an illustrative estimate.
Is it a health hazard?
The strongest evidence is on odour nuisance and its effect on quality of life. Evidence of direct toxic harm to neighbours in normal operation is weak. The serious toxic risk is mainly to workers, in accidents.
How can I request the documents?
Anyone can request administrative documents without saying why; the body has 10 days to reply and, if it does not, you can complain to CADA within 20 days. The Guarda dossier has a ready-to-use letter template.
Is the online petition legally valid?
Yes, if every signature has the full name and identity document number; the law accepts signatures collected on other electronic platforms. In the Assembleia da República, above 1,000 signatures the petitioners are heard, above 2,500 there is a committee debate and above 7,500 a plenary debate.
The other side
Promoters and supporters of biomethane have arguments. Some are true. Here they are, each with a fair answer.
"It is renewable gas that replaces imported gas."
True in principle. The EU wants 35 billion m³ of biomethane a year by 2030 and Portugal wants biomethane to cover up to 9.1% of gas use in 2030. Our question is not whether biomethane should exist, but where, at what size and with what public information.
"It is good for the climate."
Real when leaks are low: manure stored in the open already emits methane, and digestion captures it. But measured losses average between 2% and 5% of production, which eats into the benefit. Much of this is avoidable with good practice, so leak-control requirements belong in the licence.
"It turns waste into value."
Partly true: the national plan relies on urban waste, sewage sludge, agriculture, livestock and agro-industry as feedstock. The benefit depends on the waste accepted, which in Guarda has not been disclosed.
"Digestate replaces chemical fertiliser."
Valid if spread at the right time with the right equipment: band-spreading or injection greatly reduce nitrogen losses. The risks come from over-application, bad timing, spills and contaminated waste.
"It creates jobs."
The Guarda proposal announces 13 direct and about 80 indirect jobs. In another case, at Alenquer, it was about 7 direct jobs for €20.5 million. Jobs matter, but they do not replace an impact assessment.
"A well-built plant is safe."
The French accident-analysis body agrees that most incidents stem from design, maintenance, training and organisational failures, which are preventable. But they keep happening as the sector grows. That is why we ask for the guarantees to be written down before any decision.
"It smells less than spreading manure."
Spread digestate generally smells less than raw slurry. But a plant's main odour source is waste reception, not spreading.
Sign the petition Another question? Write to us
Sources on this page
- Bayle et al. (2018), Chemical Engineering Transactions, vol. 68, pp. 79–84: emissões de odor em três unidades de metanização em França
- Ata da reunião ordinária da Câmara Municipal da Guarda de 19 de junho de 2026 (Ponto 18, Proposta VPCM n.º 10/2026)
- Empresa de biometano quer instalar-se na Guarda
- MOV.AP: medições sobre imagem de satélite, outubro de 2026 (distâncias do limite da parcela à zona de exploração de água, quintas e aldeias)
- Ata da reunião ordinária da Câmara Municipal da Guarda de 13 de julho de 2026
- Ata da reunião ordinária da Câmara Municipal da Guarda de 27 de julho de 2026
- Ata da reunião ordinária da Câmara Municipal da Guarda de 10 de agosto de 2026
- A instalação de energias renováveis e de biometano no concelho da Guarda gerou, na reunião da Câmara Municipal, uma troca de argumentos sobre a necessidade da participação pública nos processos
- Despacho Conjunto APA–DGEG n.º 1/2026 (sequência de licenciamento das unidades de biometano)
- Enquadramento Legal da Digestão Anaeróbia (nota técnica)
- Participa: portal de consultas públicas (pesquisa de consultas para este projeto)
- Decreto-Lei n.º 151-B/2013, de 31 de outubro (RJAIA): avaliação de impacte ambiental, texto consolidado até ao Decreto-Lei n.º 99/2024
- Development Control Committee report P/14/700/FUL (digestão anaeróbia de Stormy Down)
- Pesquisa documental do MOV.AP: distâncias mínimas entre centrais de biogás e habitações em Portugal (nenhuma regra encontrada)
- Arrêté du 12 août 2010 relatif aux prescriptions générales applicables aux installations classées de méthanisation relevant du régime de l'enregistrement (rubrique 2781), version consolidée
- Proyecto de Decreto sobre las plantas de transformación en biometano (documento de participación pública)
- Odour emissions impact of on-farm biogas production with co-digestion: a case study in four European farms
- Rosa-dos-ventos entre Avelãs de Ambom e Pêra do Moço, 2015–2024: cálculo próprio a partir das reanálises ERA5 e ECMWF IFS (Open-Meteo)
- Climatologia do vento no local, 2021–2025: reanálise ERA5 através da Open-Meteo Historical Weather API (16 setores, velocidade, dia/noite)
- Guadalupe-Fernandez et al. (2021), Environmental Health 20: 108: poluição industrial por odores e saúde, revisão sistemática e meta-análise
- Bayle et al. (2016), Chemical Engineering Transactions, vol. 54: projeto EMAMET sobre emissões de unidades de metanização
- Informationspapier zur Sicherheit bei Biogasanlagen
- Lei n.º 26/2016, de 22 de agosto: acesso aos documentos administrativos e à informação ambiental
- Lei n.º 43/90, de 10 de agosto: exercício do direito de petição (texto consolidado, com a Lei n.º 63/2020)
- Implementing the REPowerEU plan (SWD(2022) 230): Biomethane Action Plan
- Resolução do Conselho de Ministros n.º 41/2024: Plano de Ação para o Biometano 2024–2040
- Outlook for Biogas and Biomethane: key issues affecting projects
- Scheutz e Fredenslund (2019), Waste Management 97: 38–46: emissões fugitivas de metano em 23 centrais dinamarquesas
- Methane emissions from biogas plants are higher than thought, but cost-neutral avoidable (Olczak et al. 2026, Communications Sustainability)
- Frontiers in Sustainable Food Systems (2024): revisão sobre o uso agrícola do digerido
- Weithmann et al. (2018), Science Advances 4: eaap8060: fertilizantes orgânicos como via de entrada de microplásticos no ambiente
- Uma centena de pessoas em protesto contra central de biometano em Alenquer
- Flash ARIA: Méthanisation, comment développer la filière sans développer les risques ?
- Flash ARIA: Installations de méthanisation et rejet de biogaz
Bayle et al. (2018), Chemical Engineering Transactions, vol. 68, pp. 79–84: emissões de odor em três unidades de metanização em França
Ata da reunião ordinária da Câmara Municipal da Guarda de 19 de junho de 2026 (Ponto 18, Proposta VPCM n.º 10/2026)
Empresa de biometano quer instalar-se na Guarda
MOV.AP: medições sobre imagem de satélite, outubro de 2026 (distâncias do limite da parcela à zona de exploração de água, quintas e aldeias)
- No public link
Ata da reunião ordinária da Câmara Municipal da Guarda de 13 de julho de 2026
Ata da reunião ordinária da Câmara Municipal da Guarda de 27 de julho de 2026
Ata da reunião ordinária da Câmara Municipal da Guarda de 10 de agosto de 2026
A instalação de energias renováveis e de biometano no concelho da Guarda gerou, na reunião da Câmara Municipal, uma troca de argumentos sobre a necessidade da participação pública nos processos
Despacho Conjunto APA–DGEG n.º 1/2026 (sequência de licenciamento das unidades de biometano)
Enquadramento Legal da Digestão Anaeróbia (nota técnica)
Participa: portal de consultas públicas (pesquisa de consultas para este projeto)
Decreto-Lei n.º 151-B/2013, de 31 de outubro (RJAIA): avaliação de impacte ambiental, texto consolidado até ao Decreto-Lei n.º 99/2024
Development Control Committee report P/14/700/FUL (digestão anaeróbia de Stormy Down)
Pesquisa documental do MOV.AP: distâncias mínimas entre centrais de biogás e habitações em Portugal (nenhuma regra encontrada)
- No public link