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Digestate – Note for DGENER – June 2022
Both the Fit-for-55 proposals and the recent REPowerEU communication1 aim to reduce the European
Union’s (EU) dependence on imported fossil fuel by accelerating our energy transition. These
objectives rely notably on scaling up biomethane, whose production must be increased from 17 to 35
bcm by 2030. The recently published Staff Working Document2 has outlined several possible actions
to achieve this ambitious target, unlocking the ful potential of biogas and biomethane across the EU,
proposing concrete measures to address the chal enges the sector currently faces in Europe.
One challenge, however, has not been addressed by the European Commission (EC): digestate, a by-
product of anaerobic digestion (AD), which is currently considered a waste in most Member States
(MS), despite its high agronomic value and potential for decarbonisation of the agricultural sector.
Digestate, an obstacle to the production of biomethane
Indeed, al major producers of biomethane and biogas, in Germany, Italy, and France, face the same
problem: digestate management and storage limit production. Digestate can only be spread on
agricultural land authorised by MS’ administrations, which is a bottleneck for a vast majority of
European producers. In France for example, TotalEnergies has a production capacity of 500 GWh/y,
but our digestate storage capacities are ful , and our land application authorisations insufficient, so
we are forced to slow down production wel below our production capacity
Further increasing biomethane production to unlock our ful potential also means increasing digestate
production. 40 GWh/y of additional biomethane represents 0.1‰ of the 35 bcm objective. But it
generates between 40 to 55 ktonnes of raw digestate per year3. This raw digestate contains between
200 to 2754 tonnes of nitrogen that need to be spread at least over 1,200-1,800 hectares of land5.
Reaching the target of 35 bcm therefore requires strong measures to make digestate no longer a
limit for biomethane production, but a local and ecological organic fertiliser.
Local and sustainable fertiliser to ensure food sovereignty and help the ecological transition
In addition to unlocking the production of biomethane, digestate has an underestimated yet
invaluable benefit: the ability to ensure the European Union's food sovereignty and self-sufficiency.
Digestate is in fact a local and decarbonised organic fertiliser, which, through its amending qualities,
also helps to regenerate the soil. For example, two recent studies6 have shown that the economic and
ecological benefits are higher when liquid fraction of digestate is used as a synthetic N substitute.
In 2018, the EU-28 consumed 20 mil ion tonnes of nutrients, of which 3,9 tonnes of imported mineral
nitrogen (N), i.e., 29% of European consumption7. Mineral fertilizers are energy intensive and rely
on natural gas, mainly imported from Russia for the European domestic production. Moreover, the
synthesis of NH3, based on the Haber-Bosch process is responsible for about 1% of the world’s energy
1 COM/2022/108 final
2 COM/2022/230 final
3 The production of 40 GWh/y of biomethane requires between 40-60 k tonnes of feedstocks (1200-1600t/GWh according to our experience
in France without energy crops); the AD process transforms 80 to 90% of feedstocks’ volume into digestate.
4 1 tonne of raw digestate contains 5 kg of nitrogen (N) (according to our internal technical team).
5 We are here using the ceiling of 170 kg N/ha/y for our assumption.
6 Riva et al., 2016 and Sigurnjak et al., 2019
7 Fertilizers Europe/Eurostat
consumption and 2% of world’s global natural gas consumption8; the process is also responsible for
1.2% of the global anthropogenic CO2 emissions9.
Yet Italy produces up to 30 mil ion tonnes of digestate annual y which equals to about 400 mil ion
euros fossil fertilisers savings10. Only TotalEnergies production of biomethane in France by 2030, which
wil be 3,7 TWh/year (0,35 bcm), wil save 133 ktonnes of fertilizers, offsetting 734 ktonnes of CO2 if
it replaces synthetic or mineral fertilizers.
We have the resources to make the transition to less carbon-intensive, sustainable, and reliable
fertilisers, yet we cannot currently optimise this resource as we need to. We understand and share
the concerns related to the use of digestate, however, many scientific studies have shown its
agronomic qualities.
Ensure the health and productivity of our agricultural land
Organic fertilisers such as manure or gross digestate are considered more susceptible to nitrate
leaching in the soil, considered one of major impact problem arising from agriculture. However,
studies demonstrate that NH3 emissions are on average lower for digested than untreated slurry
dur to a lower dry matter content; N2O losses are also general y lower. Moreover, organic matter in
digestate can contribute to humus formation, which is not possible with mineral fertilisers.
The AD process also reduces pathogen counts when thermophile conditions are adopted, because
of ammonia production and competition for substrate between pathogens and indigenous
microflora11. Heavy metals can also be found in digestate, but their contents are in line with the
concentrations of poultry manure, sewage culture and compost.
The sector is aware of the challenges posed by the recovery of digestated manure and biomass: the
nutrient variability in organic fertilisers made from digestate, as wel as the presence of pathogenic
microorganisms and heavy metals. Yet the necessary nutrient recovery from digested manure and
biomass across Europe is only viable if there is an effective market for the final products, not being
hindered by regulatory European requirements. The biomethane sector needs visibility and a clear
framework to produce organic fertilisers made from their digestate.
A need for rapid evolution of the regulation on digestate
As one of the major producers of biomethane, we are advocating for the rapid adoption of a European
digestate standard that wil al ow the sector to no longer limit their production of biomethane to the
production of digestate, while contributing to the greening of the agricultural sector and ensuring
European food sovereignty. This standard wil have to be adapted to the particularities of each MS,
with the aim of greening their fertilisers, implying the implementation of strict and frequent controls
to avoid any further accidents.
In this respect, the EC‘s Joint Research Center (JRC) published a Science for Policy report12 with the
objective to help define harmonised criteria that could al ow nitrogen fertilisers derived from digested
manure to be used following identical provisions applied to chemical nitrogen fertilisers. Yet we are
stil waiting for the results of this report and of the European funded project Systemic.
8 Cherkasov et al., 2015
9 Smith et al., 2020
10 Italian Biogas Association
11 Orzi et al. 2015
12 “Technical proposals for the safe use of processed manure above the threshold established for Nitrate Vulnerable Zones by the Nitrates
Directive” (91/676/EEC)
In Spain for instance, the recently published “Biogas roadmap to 2030” foresees the removal of the
waste status of digestate, as wel as a possible introduction of a mandatory quota for the
incorporation of organic fertilisers.
As the implementation of such standard might take some months, we also propose to extend the
measures foreseen by the EC to accelerate permitting process to digestates, i.e., to staff
administrations issuing land application authorisations and marketing authorisations for fertilising
materials produced from digestate, to shorten the delays. The FPR (Fertilising Products Regulation)
should also al ow the sector to use our digestate as fertiliser products, which is not the case in view of
recent developments, especially for digestate produced from animal co-products, such as manure,
among others. Discussion with DG AGRI to that respect should be intensified, and TotalEnergies would
be happy to contribute.
Bibliography and references
Cherkasov, Nikolay & Ibhadon, Alex & Fitzpatrick, P.. (2015). A review of the existing and alternative
methods for greener nitrogen fixation. Chemical Engineering and Processing: Process Intensification.
Orzi V, Scaglia B, Lonati S, Riva C, Boccasile G, Alborali GL, Adani F. The role of biological processes in
reducing both odor impact and pathogen content during mesophilic anaerobic digestion. Sci Total
Environ. 2015 Sep 1;526:116-26. doi: 10.1016/j.scitotenv.2015.04.038. Epub 2015 Apr 26. PMID:
25925189.
Riva C, Orzi V, Carozzi M, Acutis M, Boccasile G, Lonati S, Tambone F, D'Imporzano G, Adani F. Short-
term experiments in using digestate products as substitutes for mineral (N) fertilizer: Agronomic
performance, odours, and ammonia emission impacts. Sci Total Environ. 2016 Mar 15;547:206-214.
Sigurnjak, Ivona & Brienza, Claudio & Snauwaert, E. & De Dobbelaere, Anke & De Mey, Jonathan &
Vaneeckhaute, Céline & Michels, Evi & Schoumans, Oscar & Adani, Fabrizio & Meers, Erik. (2019).
Production and performance of bio-based mineral fertilizers from agricultural waste using ammonia
(stripping-)scrubbing technology. Waste Management. 89. 265-274.
Smith, C., Hil , A. K., & Torrente-Murciano, L. (2020). Current and future role of Haber–Bosch ammonia
in a carbon-free energy landscape. Energy & ; Environmental Science, 13(2), 331‑344.
