Portugal paves the way: digestate no longer a waste – a turning point for EU biogas?

 

In a major step towards creating a circular economy, Portugal has officially classified digestate – a nutrient-rich coproduct of anaerobic digestion (AD) – as a ‘by-product’ instead of ‘residue’.

The change, announced in the Portuguese Diário da República on 27 May 2025, sets a precedent that could ripple across the European U

• it is intended to be used for specific purposes
• there is a market or demand for it
• it fulfils the technical requirements for the specific purpose and complies with product legislation and standards; and
• its use does not have an overall adverse impact on the environment or human health.

The full decree can be found here (in Portuguese), and the implications are clear: digestate can now be legally used as fertiliser in Portugal without being subject to waste management constraints, streamlining its application in agriculture and closing a key loop in the biogas value chain.

Why This Decision Matters

AD transforms organic waste – such as manure, food waste and wastewater sludge – into biogas and a nutrient-rich biofertiliser called digestate. While biogas has multiple applications – including electricity and heat generation, use as a vehicle fuel, injection into the gas grid, or as a feedstock for producing refined green fuels – digestate also plays a vital role. It contains essential nutrients such as nitrogen, phosphorus and potassium, making it a powerful biofertiliser.

However, in much of the EU, digestate is still legally classified as a ‘residue’, which means it must undergo additional (often costly and bureaucratic) permitting to be applied to land. This classification undermines its value and contributes to project delays – for instance in countries like Spain, where permitting challenges are already significant.

Portugal’s decision helps unlock the full circular potential of biogas, offering a multiple benefits:

• Environmental: Reduced reliance on synthetic fertilisers, lower emissions from waste management, and improved soil health.
• Economic: Lower operating costs for biogas producers – since as a residue digestate would require compliance with specific regulations for transport, storage and application, including pasteurisation – and stronger incentives for agricultural stakeholders to adopt AD solutions.
• Social: Farming industry further development with the support of constant and reliable fertiliser production.

The light at the end of the tunnel

Neighbouring Spain is currently grappling with a slow and complex biogas permitting system, with only 11–12 biomethane (also known as renewable natural gas, or RNG) plants currently connected to the gas grid plants connected to the gas grid and 10 more expected soon. Yet many projects are stalled – not only due to red tape, but because digestate continues to be treated as waste, limiting its agricultural use and economic viability.

Moreover, public opposition to biogas in Spain – partially linked to fears of industrial farming (“macro granjas”) – has led some provinces to impose stricter regulations, creating an uneven playing field that discourages investment.

Portugal’s move shows how regulatory clarity can build confidence, improve public perception, and accelerate investment. The Portuguese decision aligns with the EU’s REPowerEU roadmap, which calls for a rapid expansion of biomethane production to reduce dependency on fossil fuels and imported gas.

Portugal’s digestate classification could serve as a model for other EU member states and countries worldwide, as it the movement of recognising digestate as a bioresource rather than a waste stream can simplify permitting procedures for biogas projects, encourage circular agricultural practices, unlock rural development opportunities and boost investor confidence in green energy infrastructure.

WBA engages with Portuguese stakeholders to support national biogas action plan

In related news, WBA Senior Technical Lead Flávio Ascenco represented the association at the 3rd Bioresidues Forum (3.º Fórum Biorresíduos) in Lisbon on 5 June 2025. Addressing an audience of policymakers, regulators and local authorities, including José Pimenta Machado, President of the Portuguese Environment Agency (APA), and Miguel Nunes of the Entidade Reguladora dos Serviços de Águas e Resíduos (ERSAR – the Regulatory Authority for Water and Waste Services), Flávio introduced WBA’s #MakingBiogasHappen programme (MBH) as a strategic tool to help Portugal build on its regulatory progress. Industry stakeholders showed strong interest in WBA’s support for a national action plan based on MBH to accelerate biogas and biomethane deployment in Portugal.

Unlocking the potential of renewable fertiliser at the World Biogas Summit

Digestate remains one of the biogas sector’s most under-utilised outputs – despite being nutrient-rich, soil-restorative, and a sustainable alternative to fossil-based fertilisers. At the World Biogas Summit 2025 (9–10 July), the roundtable on Unlocking the Potential of Renewable Fertiliser will explore how to turn digestate into a product of real economic value. What policy and market mechanisms can drive uptake? Join us in Birmingham to find out.