# Anaerobic Digestate from Biogas Plants--Nuisance Waste or Valuable Product? [PERSON]  
1 Division of Agricultural and Environmental Chemistry, Institute of Agriculture, Warsaw University of Life Sciences-SGGW, Nowouvsynowska 159, 02-766 Warsaw, Poland; magdalena,[EMAIL_ADDRESS]  
[PERSON]  
2 Department of Agricultural Sciences, University of Helsinki, Koetilathe 5, P.O. Box 28, FI-00014 Helsinki, Finland; [EMAIL_ADDRESS]  
[PERSON]  
3 Institute of Crop Science and Resource Conservation, University of Bonn, Katzenburgweg 5, D-53115 Bonn, Germany; [EMAIL_ADDRESS]  
[PERSON]  
1 Division of Agricultural and Environmental Chemistry, Institute of Agriculture, Warsaw University of Life Sciences-SGGW, Nowouvsynowska 159, 02-766 Warsaw, Poland; magdalena,[EMAIL_ADDRESS]  
Footnote 1: email: [EMAIL_ADDRESS]  
Footnote 2: email: [EMAIL_ADDRESS]  
Footnote 3: email: [EMAIL_ADDRESS]  
Footnote 4: email: [EMAIL_ADDRESS]  
Footnote 5: email: magdalena. The electrical efficiency of such systems is rather low, reaching 35\(-\)43% [4]. Biogas can also be upgraded to biomethane by CO\({}_{2}\) extraction. Biomethane can be injected into gas distribution grids, and stored and distributed as biofuel for vehicles [3]. A recent outlook on the future of biogas applications indicated that biogas may be used for the production of high-purity hydrogen [5]. Increasing biogas production is part of the European Commission's medium-term strategies. An acceleration of this development is currently expected due to political tensions in the Eastern European region [6]. The European Green Deal stipulates obtaining climate neutrality in the EU by 2050, and reduction in GHG emissions in the EU by 50% by 2030. These ambitious objectives require the implementation of a strategy of low-emission management of organic waste. Landfilling of such waste results in the emissions of GHGs, particularly CH\({}_{4}\) and CO\({}_{2}\)[7]. The European Commission has also developed the EU Methane Strategy, which focuses on three main sources of CH\({}_{4}\) emissions: energy (coal, oil, gas), agriculture, and waste. According to the estimates of the International Energy Agency [8], approximately 570 million tonnes of methane is emitted to the atmosphere annually. A share of 25% of anthropogenic emissions arises from agriculture (among others animal production and rice cultivation). The introduction of fees for methane emission from agriculture will be particularly unfavorable for farms with animal production. Methane is produced both as a result of enteric fermentation, and at the stage of storage and application of manure. In the years 2016\(-\)2019, in the European Union (EU-27) and UK, animal farming generated more than 1.4 billion tonnes of manure annually [9]. This is an immense source of potential methane emission that may be mitigated by the use of BP. The analyses of the European Commission show that biogas input could increase from 16.6 Mtoe in 2019 to 30 Mtoe by 2030, and to 45-79 Mtoe by 2050 [1;3]. Considerations regarding the possibility of increasing biogas production conducted in the context of the EU energy policy usually do not take into account the management of the digestate (DG). Furthermore, biogas production is related to generating considerable amounts of DG constituting a mixture of organic and mineral compounds with high moisture content [10]. A biogas plant with power of 1 MW (megawatt) can produce approximately 40,000 tonnes of DG annually. Promoting biomethane and hydrogen production from biogas will require the construction of larger biogas plants (approximately 3 MW). Such installations will produce substantial amounts of DG. Further, the management (i.e., recycling) of the large amount of liquid digestate derived from the AD becomes an important issue. Digestate is commonly applied to soils as an organic fertilizer [11]. DG is characterized by a high level of hydration. This limits the possibilities of its transport over large distances.