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The objective of this review is a global assessment of the economics of second‐generation biorefineries, with a focus on the use of food waste and agricultural residues for chemical production by applying biotechnological processes. Analyses are conducted on feedstock and product distribution, applied economic models, and profitability figures for the period 2013–2018. In a study of 163 articles on different biorefinery systems, the production of chemicals is identified as the second major product class, after bioenergy. Bagasse and straw are frequently analyzed second‐generation feedstocks. Based on the evaluation of 22 articles, second‐generation biorefineries producing chemicals by applying biotechnological processes proves to be economically feasible. On average, both the internal rate of return (IRR) and the return on investment (ROI) are 20% and the payback period (PP) is 6 years. The cost share of feedstock in biorefineries is between 0–50%. The price of the end product and the fermentation yields have the most impact on profitability. The processing of food waste that has industrial and municipal origins appears more economical than the processing of agricultural residues. Scientists, policy makers and entrepreneurs with an appropriate risk tolerance are advised to pay particular attention to municipal food waste and the potential economic production of carboxylic acids. For various economic issues related to biorefineries, dynamic‐deterministic models are recommended, which can be extended by a stochastic model. This review provides an initial overview of the economic feasibility of second‐generation biorefineries. Further techno‐economic analyses are required to produce statistically significant statements on key profitability figures. © 2020 The Authors. Biofuels, Bioproducts, and Biorefining published by Society of Chemical Industry and John Wiley & Sons, Ltd.
Organic pot-based production of basil (Ocimum basilicum L.) often has lower biomass yield than conventional cultivation. Previous investigations indicate that this growth impairment is related to high ammonium (NH4+) concentrations in the growing media released by the mineralization of organic nitrogen (N) fertilizers. However, as a result of this ammonification process substrate pH may also increase. Under neutral to alkaline conditions NH4+ is converted to ammonia (NH3), which is known to be phytotoxic even at low concentrations. Therefore, we investigated the impact of both ammonical N species on basil grown in a peat substrate. In total, three fertilization pot experiments were conducted in a greenhouse in order to compare the effect of different organic base dressings [250 and 750 mg N (L substrate)-1 mainly supplied by a liquid amino acid fertilizer (AAF)] and two initial substrate pH levels (5.5 and 6.5). In two treatments, 5% (v/v) mature compost was mixed into the peat 1 day and 12–days before the substrate was used for sowing, respectively. The aim of this procedure was to stimulate nitrification in this way to reduce ammonical N concentration. Ammonia concentration in the aerial plant surrounding environment was measured by using NH3 detector tubes in combination with an open-top chamber method. The results showed that the growth of basil (number of plants, fresh matter yield, plant height) was significantly inhibited in the second and third week of cultivation by rising NH3 and NH4+ exposure, as well as by a substrate pH ≥ 7.0. These adverse effects were reduced by lowering the organic base dressing rate and adjusting the initial substrate pH to 5.5. Furthermore, the addition of mature compost to peat in combination with a 12-day storage was proven to be effective for promoting nitrification in the organically fertilized substrate. As a result, plant growth was improved by both lower NH3 and NH4+ exposure as well as a faster supply of nitrate (NO3-) as an additional N source. Using this approach, it was possible to feed organically fertilized basil right from the seedling stage with a NO3--N/NH4+-N-balanced and later on providing a predominant NO3--N supply.
Um die Milchviehhaltung gibt es seit einigen Jahren auch eine öffentliche Tierwohldiskussion. Zwei Aspekte sind dabei immer wieder Gegenstand der Debatte: Die Anbindehaltung und der Weidegang. Auf Basis von qualitativen Interviews mit zivilgesellschaftlichen Verbänden und landwirtschaftlichen Verbänden zum Thema Tierwohl in der Milchviehwirtschaft wurden die Einstellungen und die Argumentationsmuster beider Verbandsgruppen zu den Haltungsformen Weidegang und Anbindehaltung ergründet. Von Interesse ist dieser Vergleich, da im Rahmen öffentlich-medialer Kommunikation die Diskussionsfronten zwischen beiden Verbandsgruppen als verhärtet dargestellt werden. Die Analyse der Aussagen der qualitativen Interviewreihe dieser Studie erlaubt die begründete Annahme, dass beide Verbandsgruppen mit den Themenkomplexen Anbindehaltung und Weidehaltung in einem wissenschaftlich orientierten Kommunikationskontext differenziert umgehen. Eine klare Polarisierung der Einstellungen zwischen beiden Verbandsgruppen war im Rahmen dieser Gesprächsformen nicht wahrnehmbar.
Jede Ernährung hat Auswirkungen auf den Gesundheitszustand des Einzelnen, auf die Umwelt und auf soziale Belange. Eine wachsende Zahl von Mahlzeiten wird in der Außer-Haus-Verpflegung eingenommen, in der eine systematische Nachhaltigkeitsbewertung nicht zur gängigen Praxis gehört. Um diese Lücke zu schließen, wurde im Rahmen des NAHGAST-Projekts ein Instrument entwickelt. Nach mehr als einem Jahr des Einsatzes des NAHGAST-Online-Tools soll nun überprüft werden, welche positiven Umwelteinflüsse durch den Einsatz des Instruments realisiert werden können. Aus diesem Grund befasst sich dieser Artikel mit der Frage, ob ein Online-Tool Akteure aus dem Bereich des Außer-Haus-Verzehrs in die Lage versetzen kann, ihre Mahlzeiten im Hinblick auf Aspekte einer nachhaltigen Ernährung zu überarbeiten. Darüber hinaus wird die Frage beantwortet, wie sich konkrete Rezeptüberarbeitungen der beliebtesten Mittagsgerichte auf den materiellen Fußabdruck sowie auf den Carbon Footprint auswirken.
Zusammenfassend lässt sich sagen, dass ein Online-Tool individuelle Nachhaltigkeitspfade für Akteure im und ermöglicht eine eigenständige Rezeptüberarbeitung für bereits bestehende Gerichte. Mahlzeiten. Die Ergebnisse zeigen, dass bereits geringfügige Änderungen in den Rezepten zu Einsparungen von bis zu einem Drittel führen können beim CO2-Fußabdruck sowie beim Materialfußabdruck führen können. Bezogen auf den Außer-Haus-Verzehr Außer-Haus-Verzehr ergibt sich daraus das Potenzial für erhebliche Multiplikationseffekte, die den Weg für die Verbreitung von nachhaltiger Ernährung ebnen.
Ecological restoration of an urban demolition site through introduction of native forb species
(2020)
Urban brownfields can provide habitats for endangered native plant species but may also support invasive non native species. The aim of our study was to develop and test different measures for the ecological restoration of an urban brownfield. We aimed to enhance native plant species richness by seeding two native forb seed mix tures containing 25 (HD-mixture) and 13 species (LD-mixture), respectively, without affecting spontaneously colonizing plant species of nature conservation value. Additionally, we tested the effects of species introduction and mowing on the establishment of invasive non-native plant species, woody species development, and per ennial grass dominance.
With establishment rates of 84% (HD) and 92% (LD) in the first study year and about 60% for both seed mixtures in the fourth year, species introduction was successful and led to rapid re-vegetation of the formerly bare brownfield. Although seeding did not result in increased species richness using either seed mixture, the dominance of perennial grasses was significantly reduced by the establishment of forb species from the HD mixture. Overall, we observed the spontaneous establishment of ten plant species of conservation value; seeding affected these species only temporarily, in the second year. Seeding (with either seed mixture) and mowing both resulted in reduced cover of woody species and a lower frequency of the invasive non-native Robinia pseudoa cacia.
Our study demonstrated the high nature conservation value of dry and nutrient-poor urban brownfields for spontaneously occurring threatened plant species. Further studies have to evaluate if the reduced cover of grasses and woody species through introduction of site-specific native forb species might increase these sites’ aesthetic value and broader acceptance of brownfields by urban residents.
Injection of slurry or digestate below maize seeds is a relatively new technique developed to improve nitrogen use efficiency. However, this practice has the major drawback of increasing nitrous oxide (N2O) emissions. The application of a nitrification inhibitor (NI) is an effective method to reduce these emissions. To evaluate the effect of the NI 3,4‐dimethypyrazole phosphate (DMPP) on N2O emissions and the stabilization of ammonium, a two‐factorial soil‐column experiment was conducted. PVC pipes (20 cm diameter and 30 cm length) were used as incubation vessels for the soil‐columns. The trial consisted of four treatments in a randomized block design with four replications: slurry injection, slurry injection + DMPP, digestate injection, and digestate injection + DMPP. During the 47‐day incubation period, N2O fluxes were measured twice a week and cumulated by linear interpolation of the gas‐fluxes of consecutive measurement dates. After completion of the gas flux measurement, concentration of ammonium and nitrate within the soil‐columns was determined. DMPP delayed the conversion of ammonium within the manure injection zone significantly. This effect was considerably more pronounced in treatment digestate + NI than in treatment slurry + NI. Regarding the cumulated N2O emissions, no difference between slurry and digestate treatments was determined. DMPP reduced the release of N2O significantly. Transferring the results into practice, the use of DMPP is a promising way to reduce greenhouse gas emissions and nitrate leaching, following the injection of slurry or digestate.
Establishment of calcareous grassland on ex-arable fields by introducing target species is one of the most frequently used methods to restore the species assemblages of this highly endangered habitat type. The present study evaluates the long-term success of calcareous grassland restoration on former arable land in the vicinity of one of the oldest nature reserves in Bavaria, the “Garchinger Heide”. The restoration experiment combined different measures like topsoil removal, transfer of freshly cut seed-containing hay and additional sowing to the following variants in a 21-year experiment: (1) No topsoil removal, no hay transfer (control), (2) no topsoil removal with immediate hay transfer, (3) topsoil removal with immediate hay transfer and (4) topsoil removal with hay transfer 10 years after the start of restoration. Eleven Red List species which had not been transferred successfully were additionally sown after 9 to 19 years. Due to a limited availability of seeds, sowing of these species was mainly restricted to areas with topsoil removal, where better establishment was expected due to low vegetation cover. Five rare species with abundant seed production were also sown to plots without topsoil removal and hay transfer. The nature reserve served both as the donor area of the target species and as the reference to evaluate restoration success. Regarding aboveground biomass and total vegetation cover, greatest similarity to the donor site was observed on plots without topsoil removal. In contrast, the highest numbers of target species occurred on plots with topsoil removal, hay transfer and additional sowing. Similarity in species composition between restoration sites and the reference area increased over time, but species composition of restored sites did not fully reflect the reference after 21 years. One reason for the remaining dissimilarity was probably that topsoil removal favored stress tolerant species which were less common on the mature and more fine-grained soils of the nature reserve. Plots without topsoil removal still differed from the reference by their high vegetation cover and a significantly higher proportion of mesophytic grassland species. The study also showed that 19 Red List species were successfully established on the former arable fields, eight of them presumably by sowing. Nevertheless, various other rare species have not been observed yet. Results on functional traits characterizing environmental adaptation and reproduction also underlined the differences between restoration plots and the reference site. Our study presents a ʽdynamic restoration approachʼ where managers evaluated the original factorial treatments after a decade and modified them by additional treatments where development was sub-optimal. Such additional treatments may have confounded the experimental design, but from a management perspective proved to be a promising option to establish species rich grassland of high conservation value with a reasonable expenditure of time.
Gebäude beanspruchen Ressourcen und verändern die Umwelt. Die Landwirtschaft benötigt oftmals großvolumige Gebäude. Eine nachhaltigere landwirtschaftliche Baukultur wäre deshalb begrüßenswert. Für das agrarische Bauen könnte eine verstärkte Verwendung des Rohstoffs Holz eine Perspektive darstellen. Holz überzeugt durch zahlreiche ökologische Vorteile wie die langfristige Kohlenstoffbindung oder eine einfache Recycelbarkeit. In Deutschland spielt Holz beim landwirtschaftlichen Bauen allerdings eine immer geringere Rolle. Diese Studie stellt Meinungsbilder deutscher LandwirtInnen zum Holzeinsatz beim Stallbau zusammen. Es wurden zehn Gruppendiskussionen zum Themenfeld landwirtschaftliche Baukultur in verschiedenen deutschen Schwerpunktregionen der Rinderhaltung gestaltet. Die Auswertungen zeigen, dass die LandwirtInnen weitestgehend die optische Wirkung von Holz schätzen, aber häufig an der Dauerhaftigkeit von Holzställen zweifeln.
In this paper, we evaluate the application of Bayesian Optimization (BO) to discrete event simulation (DES) models. In a first step, we create a simple model, for which we know the optimal set of parameter values in advance. We implement the model in SimPy, a framework for DES written in Python. We then interpret the simulation model as a black box function subject to optimization. We show that it is possible to find the optimal set of parameter values using the open source library GPyOpt. To enhance our evaluation, we create a second and more complex model. To better handle the complexity of the model, and to add a visual component, we build the second model in Simio, a commercial off-the-shelf simulation modeling tool. To apply BO to a model in Simio, we use the Simio API to write an extension for optimization plug-ins. This extension encapsulates the logic of the BO algorithm, which we deployed as a web service in the cloud.
The fact that simulation models are black box functions with regard to their behavior and the influence of their input parameters makes them an apparent candidate for Bayesian Optimization (BO). Simulation models are multivariable and stochastic, and their behavior is to a large extent unpredictable. In particular, we do not know for sure which input parameters to adjust to maximize (or minimize) the model’s outcome. In addition, the complex models can take a substantial amount of time to run.
Bayesian Optimization is a sequential and self-learning algorithm to optimize black box functions similar to as we find them in simulation models: they contain a set of parameters for which we want to identify the optimal set, they are expensive to evaluate, and they exhibit stochastic noise. BO has proven to efficiently optimize black box functions from varius disciplines. Among those, and most notably, it is successfully applied in machine learning algorithms to optimize hyperparameters.