Integrated Bioenergy and Food Production—A German Survey on Structure and Developments of Anaerobic Digestion in Organic Farming Systems

Abstract

Rising global energy needs and limited fossil fuel reserves have led to increased use of renewable energies. In Germany, this has entailed massive exploitation of agricultural biomass for biogas generation, associated with unsustainable farming practices. Organic agriculture not only reduces negative environmental impacts, organic farmers were also prime movers in anaerobic digestion (AD) in Germany. This study's aim was to identify the structure, development, and characteristics of biogas production associated with organic farming systems in order to estimate further development, as well as energetic and associated agronomic potentials. Surveys were conducted among organic farms with AD technology. 144 biogas plants could be included in the analysis. Total installed electrical capacity was 30.8 MWel, accounting for only 0.8% of the total installed electrical capacity in the German biogas sector. Recently, larger plant types (>250 kWel) with increased use of (also purchased) energy crops have emerged. Farmers noticed increases in yields (22% on average) and quality of cash crops in arable farming through integrated biogas production. In conclusion, although the share of AD in organic farming is relatively small it can provide various complementary socio-ecological benefits such as the enhancement of food output through digestate fertilization without additional need for land, while simultaneously reducing greenhouse gas emissions from livestock manures and soils. However, to achieve this OPEN ACCESSSustainability 2015, 7 10710 eco-functional intensification, AD systems and their management have to be well adapted to farm size and production focus and based primarily on residue biomass.

Valorization of Value-Added Resources from the Anaerobic Digestion of Swine-Raising Manure for Circular Economy in Taiwan

“…According to Article 4 of the Act, the central governing agency shall announce the categories, types, and specifications of fertilizers, including nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, minor trace elements fertilizer, organic matter fertilizer, compound fertilizer, plant growth aid, microbial fertilizer, and other fertilizers. Obviously, the biogas digestate belongs to one of the organic matter fertilizers due to its richness in soil nutrients [14][15][16][17][18][19][20]. Table 3 lists the composition specifications/limits of organic matter fertilizers (livestock manure compost item No.…”

“…As mentioned above, digestate is a by-product from the AD of the biogas plant production, which is rich in in minerals (such as nitrogen, phosphorus, calcium, and magnesium) and organic matter [14]. In this regard, biogas-digestate has been used as a sustainable fertilizer for crop production in the organic farming system (OFS) [17][18][19][20]. More significantly, the organic agriculture promotion in Taiwan echoed the UN Agenda 2030 for the SDGs.…”

Mineralisation of distinct biogas digestate qualities directly after application to soil

“…Biogas is an important energy source produced by the anaerobic fermentation of raw faecal slurries and plant residues (Blumenstein et al 2015;Möller 2015). In the early eighties of the last century, biogas plants were installed by several biodynamic farmers in north-east Baden-Württemberg, Germany, to gain independence from nuclear power electricity, which was strongly expanding during that time (Wentzel et al 2015).…”

The Valorization of Ammonia in Manure Digestate by Means of Alternative Stripping Reactors

“…The main issues concerning the landspreading of digestate on agricultural soils that represents the main route are related to the high content of nutrients especially nitrogen [6] and represent the increasing number of AD plants especially in the region with intensive livestock farming [7]. Therefore, in order to comply with the European Nitrates Directive (91/676/EEC) [8], suitable treatments for nitrogen reduction in digestate must be applied.…”