Abstract

Ziel dieser Arbeit war es, am Beispiel des Klärwerks Schönerlinde, Szenarien, in denen Biomethan oder Wasserstoff, als Alternative zu einem Referenzszenario ohne „grüne“ Gase, erzeugt werden, zu modellieren und jene Szenarien auf technische Realisierbarkeit, Potential zur Einsparung von CO2-Äquivalenten und wirtschaftliche Durchführbarkeit zu untersuchen. So sollte überprüft werden, wie eine optimale Energienutzung/-versorgung des Klärwerks Schönerlinde in naher Zukunft aussehen könnte. Dafür wurde zunächst ein Basisszenario für das Klärwerk Schönerlinde entworfen, welches zukünftige Energie- und Wärmeverbräuche sowie Faulgasproduktion des Klärwerks widerspiegelt und eine komplette Verstromung des Faulgases in den BHKWs vor Ort sowie eine Einspeisung von überschüssigem Strom aus Windkraft vorsieht. Basierend darauf wurden alternative „Grünes Gas“-Szenarien betrachtet. Dabei wurden Aminwäscheszenarien, mit unterschiedlicher Betriebsweise der BHKWs, Elektrolyseszenarien, mit unter-schiedlicher Auslastung des Elektrolyseurs sowie Methanisierungsszenarien, in denen Aminwäsche, Elekt-rolyseur und biologische Methanisierung zum Einsatz kommen, modelliert. Für die Modellierung und somit Darstellung der Szenarien wurde ein dynamisches Modell in Microsoft Excel zusammengestellt. In dem Modell wurden Daten zu Energie- und Wärmeverbräuchen eingetragen und Energie- sowie Jahresbilanzen hinsichtlich der Lastgänge für jeden Zeitschritt (1h) einzeln berechnet, um eine realistische Einschätzung der zeitlichen Dynamik und der Speicherstände zu gewährleisten. Im Hinblick auf technische Aspekte ist bei den Aminwäscheszenarien eine strom- oder wärmegeführte Betriebsweise der BHKWs möglich. Dies hat entsprechenden Einfluss auf die Auslastung der Aminwäsche sowie der erzeugten Biomethanmenge. Im Hinblick auf die Treibhausgasbilanz wurde festgestellt, dass die Aminwäscheszenarien, mit Herstellung von Biomethan, ökologisch sinnvoll sind. Mit steigendem Anteil von Grünstrom aus erneuerbaren Energiequellen im Netz sind darüber hinaus noch weitere Einsparungen möglich. Wirtschaftlich betrachtet sind die Aminwäscheszenarien gegenwärtig unwirtschaftlicher als das Referenzszenario. Bei den Elektrolyseszenarien ist eine, nach einem Lastgang geschaltete, Elektrolyse am sinnvollsten, da auf diese Weise der Elektrolyseur konstant betrieben wird. Die Elektrolyseszenarien sind, hinsichtlich ihrer Treibhausgasbilanz und Wirtschaftlichkeitsbetrachtung, ungünstiger als das Referenzszenario und nur vor-teilhaft, wenn günstiger EE-Strom für die Elektrolyse bezogen wird. Selbst bei Nutzung des Sauerstoffs, aus der Elektrolyse, in der Ozonung kann keine positive Wirtschaftlichkeit erzielt werden. Die Szenarien mit biologischer Methanisierung und BHKWs erzeugen 12% zusätzliches Biomethan. Hinsichtlich ihrer Treibhausgasbilanz und Wirtschaftlichkeitsbetrachtung sind sie jedoch, genauso wie die Elektrolyseszenarien, nur vorteilhaft, wenn günstiger EE-Strom für die Elektrolyse bezogen wird, da mit Wirkungsgradverlusten von knapp 25% bei der Wasserstoffherstellung gerechnet werden muss. Haupteinflusspunkte auf den zukünftigen Erfolg, in Hinblick auf umwelttechnische und wirtschaftliche Aspekte der „Grünes-Gas“-Szenarien, sind die Entwicklung der Kosten und Emissionsfaktoren von Netzstrom sowie Erlösen aus Biomethan und Wasserstoff, welche gegenwärtig noch keinen Wettbewerb zur kompletten Verstromung des Faulgases in BHKWs darstellen.

Grassauer, F. , Herndl, M. , Iten, L. , Stüssi, M. , Harder, R. , Gaillard, G. , Kraus, F. (2022): D5.2. Environmental profile of agro-ecosystems and of the food value chain.

Hoehere Bundeslehr-Und Forschungsanstalt Fuer Landwirtschaft Raumberg-Gumpenstein

Abstract

Satisfying the ever-growing global food demand was traditionally done by expanding and intensifying agricultural production. However, these practices led to considerable environmental impacts as the food value chain nowadays accounts for considerable amounts of greenhouse gas emissions (26 % of global anthropogenic emissions) and eutrophication (78 % of global emissions). Therefore, the project Circular Agronomics aims at the assessment of practical and technical solutions to improve the current carbon (C), nitrogen (N), and phosphorus (P) cycling in European agro-ecosystems and related up- and downstream processes within the food supply chain. The project comprises six case studies from different regions in the European Union (i.e., Catalunia, Spain; Brandenburg, Germany; Lungau, Austria; Emilia-Romagna, Italy; Gelderland, Netherlands; South Moravia, Czech Republic) that planned to conduct ten different experiments in order to test the practical and technical solutions by either a combination of a technical sub-system with a subsequent agricultural field experiment or a sole agricultural field experiment. However, different restraints led to waiver or postponement of certain traits of some experiments. Therefore, the data collection only yielded seven experiments with complete data. Regarding the other three experiments, at least data on the respective technical sub-systems could be collected. The experiments were subsequently assigned to three innovative strategies which aim at different compartments of agricultural production (i.e., (1) nutrient management in crop production, (2) nutrient management in livestock production, (3) and waste management and nutrient/carbon recovery). The different experiments were analyzed according to their respective system description and in compliance with the methodology as outlined in Deliverable 5.1. Moreover, abiotic resource depletion was added as an environmental impact category due to its relevance for experiments that focus on mineral fertilizer as impacts from background processes such as mining. The strategy of nutrient management in crop production comprised three experiments that investigated different management parameters to increase the nutrient efficiency in crop production. The results show that increasing levels of N fertilization leads to higher yields and increases emissions (abiotic resource depletion and eutrophication), which is even more pronounced under a dry climate. Regarding the timing of fertilization, four weeks after sowing showed the least emissions, which can be explained by the higher N demand of the plants at this stage. Moreover, the test of different tillage regimes indicated the no-tillage variant to be favorable in terms of environmental impacts per kg crop. Results of two experiments assigned to the innovative strategy of nutrient management in livestock production showed the beneficial effects of precision feeding in terms of mitigating greenhouse gas emissions and eutrophication due to a needs-oriented supply of nutrients that leads to lower losses. It could further be shown that the extensive management of organic dairy farms can be very efficient in terms of eutrophication if the management intensity matches the natural production potential of the agricultural area of the farm. The remaining five experiments examined improvements in waste management and carbon/nutrient recovery by using waste streams as potential sources of nutrients or reducing emissions by capturing nutrients. Regarding three investigated digestate treatment concepts, microfiltration/ microsieving revealed the lowest environmental impacts. Regarding capturing nutrients, the struvite technology can recover and subsequently recycle these nutrients in a comparably clean and plant available form from soybean wastewater treatment with low environmental impacts. The membrane technology seems to be an electricity-saving alternative compound for whey thickening compared to centrifuges. Overall, it could be shown that the innovative technical sub-systems cause additional efforts (such as electricity consumption) and corresponding additional impacts. However, the subsequent farming systems should be able to achieve reduced emissions. Regarding the non-renewable energy demand and global warming potential of the observed systems, it seems rather unlikely that a corresponding reduction in emissions by farming systems can be realized. Conversely, it is more likely that this trade-off can be achieved for acidification and eutrophication (especially ammonia emissions), where agriculture has a crucial role. The report shows particular areas of improvement for process engineers focusing on optimization of technologies and farmers/agricultural researchers for optimization of their nutrient management behaviors. From the comparison, particular done for one experiment and separated assessments done for others and incomplete data-sets for several technical and farming systems, we only can state that such a hybrid out of technology and agriculture may reduce environmental impacts if it is well applied, however there it is unlikely that it is always well applied. Nonetheless, this aspect of dedicated nutrient management and emission mitigation should be investigated further.

Remy, C. , Toutian, V. , Loderer, C. (2022): Thermal or thermo-alkaline hydrolysis for waste activated sludge? Comparison of pros and cons for a Berlin WWTP.

International Water Association Publishing. IWA Water and Resource Recovery Conference Poznan, Poland 2022

Abstract

The objetive of this study is the practical application of an ammonium-based oxygen control for the operational optimization of the membrane wastewater treatment plant in Stahnsdorf by means of modern measurement technology on a pilot scale. For this purpose, the following two research questions are posed: How can ammonium-based oxygen control be implemented for MBR technology with safe nitrogen removal? And can energy consumption be reduced using ammonium-based oxygen control?

To answer these questions, oxygen-based oxygen control was conducted for a period of 17 days and ammonium-based control for 57 days for comparison. This was initially started as a "feedback control", but was changed to the "feedforward control" due to unreliable probe measurements in the nitrification and effluent. Laboratory and on-line data were collected over these sampling periods. The experimental results showed that effluent quality is highly dependent on the reliability of the measurement technique. The calculation of air volume and power consumption suggested that the ammonium-based control saved both air volume and power, and thus energy. However, effluent quality needs to be improved, which can be solved by expansion with other controls.

Williams, A. , Nadeu, E. , Koslowski, J. , Rose, E. , Serebrennikov, D. , Thorne, F. , McCarthy, S. , Muchiri, S. , Tuyishime, N. (2022): D4.4. Effects by international trade in relation to EU agriculture.

East African Farmer Association, RISE Foundation, TEAGASC Agriculture and Food Development Authority, Kompetenzzentrum Wasser Berlin gGmbH

Abstract

This deliverable contains the outcomes of our exploitation task in the project Circular Agronomics. Five technologies, namely solar drying, microfiltration, vacuum degasification, K struvite recovery and membrane treatment had been transferred to a potential replication site and been evaluated under these large-scale conditions. The studies consider a site description, the integration of technology into the site, a cost estimation, a forecast on emissions, legal aspects to be considered and finally some conclusions on roll-out and/or further technology development. To date the technologies reached TRL 6 or 7 and are applied to solid or liquid fraction of agricultural digestate or wastewater and waste streams from food industry. The scale of installations varies from concept studies for a capacity less than 1 m³/h towards 15 m³/h resulting in different cost profiles. A cross-cutting conclusion on different influencing factors such as technology readiness, their environmental benefits, their cost sufficiency and political factors influencing potential replication is delivered. The final paragraph of each concept study concludes with the recommendations for technology provider and or site owner in terms of further development and provides answers about uncertainties in terms of investment decisions. A further synthesis of the main finding of this work will be published in Deliverable 6.9 - a brochure about the technologies.

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