Supplying Europe with Hydrogen and Negative Emissions – A Model-Based Assessment

Elektrolysewasserstoff und aus der Umgebungsluft abgeschiedenes und anschließend eingespeichertes CO2 (DACCS) sind zwei Optionen für die Umsetzung ambitionierter Klimaschutzstrategien in Deutschland und Europa. Strombasierter Wasserstoff kann dabei potentiell fossile Energieträger in vielen Prozessen und Anwendungen der klassischen Energienachfragesektoren ersetzen und im Umwandlungssektor als saisonaler Energiespeicher fungieren. Negative Emissionen mittels DACCS können unvermeidbare Restemissionen, z. B. aus der Landwirtschaft, kompensieren und in ökonomische Konkurrenz mit alternativen Treibhausgasminderungsstrategien treten. Beide Optionen interagieren stark mit einem im Wandel befindlichen Energieangebotssystem. Ziel dieser Dissertation ist deshalb die quantitative Analyse der Wechselwirkungen des Wasserstoffsystems mit dem Umwandlungssektor und der Bereitstellung von Negativemissionen mittels DACCS im Kontext eines treibhausgasneutralen europäischen Energiesystems. Zur Adressierung des Forschungsgegenstandes wird das auf die Abbildung von Strom- und Wärmebereitstellung ausgerichtete Kostenminimierungsmodell Enertile zu einem multidirektionalen Energieangebotsmodell erweitert. Kern der methodischen Weiterentwicklung ist die Modellierung der Interaktionen von Wasserstoff- und DACCS-Technologien mit zukünftig auf erneuerbare Energien ausgelegten Strom- und Wärmesystemen. An Hand von Szenariostudien werden Potentiale von Wasserstoff und DACCS bestimmt und wesentliche Treiber für ihre Nutzung identifiziert. Für Wasserstoff zeigen die Modellergebnisse, dass Europa ein substantielles Wasserstofferzeugungspotential hat und sich in großen Teilen kosteneffizient selbstversorgen kann. Elektrolyseure und Wasserstoffkraftwerke werden zu zentralen Flexibilitätsgebern im optimierten erneuerbaren Stromsystem. Die Wasserstofferzeugung folgt dabei der kostengünstigen erneuerbaren Stromerzeugung. In der Kostenminimierung übernehmen Wasserstoffspeicher mit einem saisonalen und Wasserstofftransportnetze mit einem überregionalen Ausgleich von Angebot und Nachfrage fundamentale Aufgaben im Energiesystem. In den Modellergebnissen für Europa gibt es DACCS-Potentiale zu Kosten zwischen 60 und 270 €/tCO2. Im Literaturvergleich können diese technischen Negativemissionen mit vergleichsweise teuren, alternativen Treibhaugasminderungsoptionen konkurrieren. In der Optimierung erfüllen Schweden, die Iberische Halbinsel, Norwegen, und Finnland zentrale Voraussetzungen für geeignete DACCS-Standorte: Ungenutzte Stromerzeugungs- und geologische Speicherpotentiale. Diese Dissertation wurde im Rahmen meiner Forschungsarbeit am Fraunhofer-Institut für System- und Innovationsforschung (ISI) erstellt und von Prof. Dr. Martin Wietschel am Institut für industrielle Produktion (IIP) des Karlsruher Instituts für Technologie (KIT) betreut. Dr. rer. pol. ist der angestrebte Abschluss

Topic Space: Rapid Prototyping a Mobile Augmented Reality Recommendation App

With funding from an Institute of Museum and Library Services (IMLS) Sparks! Ignition Grant, researchers from the University of Illinois Library designed and tested a mobile recommender app with augmented reality features. By embedding open source optical character recognition software into a “Topic Space” module, the augmented reality app can recognize call numbers on a book in the library and suggest relevant items that are not shelved nearby. Topic Space can also show users items that are normally shelved in the starting location but that are currently checked out. Using formative UX methods, grant staff shaped app interface and functionality through early user testing. This paper reports results of UX testing; a redesigned mobile interface, and provides considerations on the future development of personalized recommendation functionality.IMLS A0279Ope

Supply curves of electricity-based gaseous fuels in the MENA region

The utilization of electricity-based fuels (e-fuels) is a potential strategy component for achieving greenhouse gas neutrality in the European Union (EU). As renewable electricity production sites in the EU itself might be scarce and relatively expensive, importing e-fuels from the Middle East and North Africa (MENA) could be a complementary and cost-efficient option. Using the energy system model Enertile, supply curves for hydrogen and synthetic methane in the MENA region are determined for the years 2030 and 2050 to evaluate this import option techno-economically. The model optimizes investments in renewable electricity production, e-fuel production chains, and local electricity transport infrastructures. Analyses of renewable electricity generation potentials show that the MENA region in particular has large low-cost solar power potentials. Optimization results in Enertile show for a weighted average cost of capital of 7% that substantial hydrogen production starts above 100 €/MWhH2 in 2030 and above 70 €/MWhH2 in 2050. Substantial synthetic methane production in the model results starts above 170 €/MWhCH4 in 2030 and above 120 €/MWhCH4 in 2050. The most important cost component in both fuel production routes is electricity. Taking into account transport cost surcharges, in Europe synthetic methane from MENA is available above 180 €/MWhCH4 in 2030 and above 130 €/MWhCH4 in 2050. Hydrogen exports from MENA to Europe cost above 120 €/MWhH2 in 2030 and above 90 €/MWhH2 in 2050. If exported to Europe, both e-fuels are more expensive to produce and transport in liquefied form than in gaseous form. A comparison of European hydrogen supply curves with hydrogen imports from MENA for 2050 reveals that imports can only be economically efficient if the two following conditions are met: Firstly, similar interest rates prevail in the EU and MENA; secondly, hydrogen transport costs converge at the cheap end of the range in the current literature. Apart from this, a shortage of land for renewable electricity generation in Europe may lead to hydrogen imports from MENA. This analysis is intended to assist in guiding European industrial and energy policy, planning import infrastructure needs, and providing an analytical framework for project developers in the MENA region

Die Deutsche Verwaltungselite der Regierungen Brandt bis Merkel II. Herkunft, Zusammensetzung und Politisierung der Führungskräfte in den Bundesministerien

Dieser Beitrag präsentiert die Befunde der Elitestudie Politisch-Administrative Elite 2013 (PAE 2013) über Zusammensetzung und Politisierung der bundesdeutschen Verwaltungseliten. Diese vierte nationale Replikation der Comparative Elite Studies zum Ende der 17. Legislaturperiode bringt überraschende Entwicklungen ans Licht: Hinsichtlich der Zusammensetzung des Personals schreitet zwar die Feminisierung auch auf den Leitungsebenen fort und eine Berufsvererbung kann nicht mehr festgestellt werden, allerdings erlebt die Juristendominanz mit erstmals seit Jahrzehnten steigenden Werten ein Wiedererstarken. Der Grad an formaler Politisierung überrascht: Trotz des Verbleibs der CDU/CSU an der Macht findet ein umfassender Personalaustausch statt. Diese teils im Widerspruch zu etablierten Trends und Theorien stehenden Entwicklungen zeigen, dass das Feld der administrativen Elitenforschung auch zukünftig besondere Aufmerksamkeit verdient

Thompson revisited. Ein empirisch fundiertes Modell zur Qualität von "Quality-TV" aus Nutzersicht

Was bedeutet das Attribut „Quality-TV“ eigentlich für das Publikum? Nach welchen Kriterien beurteilen Zuschauerinnen und Zuschauer, ob eine Serie Qualitätsfernsehen ist oder nicht? Im Bereich der rezipientenorientierten Qualitätsforschung bezüglich Fernsehserien sind bislang fast ausschließlich qualitativ erhobene Modelle bedeutsam, am bekanntesten sicherlich die bereits 1996 von Robert J. Thompson vorgeschlagenen 12 Kriterien. Die vorliegende Untersuchung widmet sich nun der Frage, ob diese Qualitätskriterien tatsächlich die „richtigen“ sind. Sind sie für die Zuschauer/innen von Serien bedeutsam für die Einschätzung, ob ein Programm „Quality-TV“ ist oder nicht? Bislang fehlt eine empirische Fundierung der einzelnen Merkmale. Ebenso ungeklärt ist bislang, ob es eine Rangfolge dieser Merkmale gibt. Welche sind bedeutsamer, welche weniger wichtig für die Wahrnehmung einer Serie als Qualitätsprodukt? Die Studie hat Thompsons Vorschlag (unter Bezugnahme auf weitere Studien zum Thema (z.B. Cardwell 2007; Feuer 2007; Dreher 2010; Blanchett 2011; Kumpf 2011) operationalisiert und in einer standardisierten Befragung der Nutzer von 13 Onlineforen zu Qualitätsserien (n=1382) getestet. Auf Basis dieser Befragung kann statistisch nachgewiesen werden, welche Merkmale von den Zuschauer/innen als besonders wichtig angesehen werden und wie diese zu Qualitätsfaktoren zusammengefasst werden können, die das Phänomen „Quality-TV“ aus Zuschauersicht tatsächlich beschreiben können

The role of hydrogen in a greenhouse gas-neutral energy supply system in Germany

Hydrogen is widely considered to play a pivotal role in successfully transforming the German energy system, but the German government\u27s current “National Hydrogen Strategy” does not specify how hydrogen utilization, production, storage or distribution will be implemented. Addressing key uncertainties for the German energy system\u27s path to greenhouse gas-neutrality, this paper examines hydrogen in different scenarios. This analysis aims to support the concretization of the German hydrogen strategy. Applying a European energy supply model with strong interactions between the conversion sector and the hydrogen system, the analysis focuses on the requirements for geological hydrogen storages and their utilization over the course of a year, the positioning of electrolyzers within Germany, and the contributions of hydrogen transport networks to balancing supply and demand. Regarding seasonal hydrogen storages, the results show that hydrogen storage facilities in the range of 42 TWhH2 to 104 TWhH2 are beneficial to shift high electricity generation volumes from onshore wind in spring and fall to winter periods with lower renewable supply and increased electricity and heat demands. In 2050, the scenario results show electrolyzer capacities between 41 GWel and 75 GWel in Germany. Electrolyzer sites were found to follow the low-cost renewable energy potential and are concentrated on the North Sea and Baltic Sea coasts with their high wind yields. With respect to a hydrogen transport infrastructure, there were two robust findings: One, a domestic German hydrogen transport network connecting electrolytic hydrogen production sites in northern Germany with hydrogen demand hubs in western and southern Germany is economically efficient. Two, connecting Germany to a European hydrogen transport network with interconnection capacities between 18 GWH2 and 58 GWH2 is cost-efficient to meet Germany\u27s substantial hydrogen demand

Quality control and error assessment of the Aeolus L2B wind results from the Joint Aeolus Tropical Atlantic Campaign

Since the start of the European Space Agency's Aeolus mission in 2018, various studies were dedicated to the evaluation of its wind data quality and particularly to the determination of the systematic and random errors in the Rayleigh-clear and Mie-cloudy wind results provided in the Aeolus Level-2B (L2B) product. The quality control (QC) schemes applied in the analyses mostly rely on the estimated error (EE), reported in the L2B data, using different and often subjectively chosen thresholds for rejecting data outliers, thus hampering the comparability of different validation studies. This work gives insight into the calculation of the EE for the two receiver channels and reveals its limitations as a measure of the actual wind error due to its spatial and temporal variability. It is demonstrated that a precise error assessment of the Aeolus winds necessitates a careful statistical analysis, including a rigorous screening for gross errors to be compliant with the error definitions formulated in the Aeolus mission requirements. To this end, the modified Z score and normal quantile plots are shown to be useful statistical tools for effectively eliminating gross errors and for evaluating the normality of the wind error distribution in dependence on the applied QC scheme, respectively. The influence of different QC approaches and thresholds on key statistical parameters is discussed in the context of the Joint Aeolus Tropical Atlantic Campaign (JATAC), which was conducted in Cabo Verde in September 2021. Aeolus winds are compared against model background data from the European Centre for Medium-Range Weather Forecasts (ECMWF) before the assimilation of Aeolus winds and against wind data measured with the 2 µm heterodyne detection Doppler wind lidar (DWL) aboard the Falcon aircraft. The two studies make evident that the error distribution of the Mie-cloudy winds is strongly skewed with a preponderance of positively biased wind results distorting the statistics if not filtered out properly. Effective outlier removal is accomplished by applying a two-step QC based on the EE and the modified Z score, thereby ensuring an error distribution with a high degree of normality while retaining a large portion of wind results from the original dataset. After the utilization of the described QC approach, the systematic errors in the L2B Rayleigh-clear and Mie-cloudy winds are determined to be below 0.3 m s−1 with respect to both the ECMWF model background and the 2 µm DWL. Differences in the random errors relative to the two reference datasets (Mie vs. model is 5.3 m s−1, Mie vs. DWL is 4.1 m s−1, Rayleigh vs. model is 7.8 m s−1, and Rayleigh vs. DWL is 8.2 m s−1) are elaborated in the text.</p

Multimodal Virtual Reality-Based Assessment of Adult ADHD : A Feasibility Study in Healthy Subjects

Neuropsychological assessments are often surprisingly inaccurate in mapping clinically-reported attention-deficit hyperactivity disorder (ADHD) symptoms, presumably due to their low ecological validity. Virtual reality (VR) might offer a potential solution for this problem, given its capability to generate standardized and yet highly realistic virtual environments. As the first adaptation of existing virtual classroom scenarios to an adult population, we developed a Virtual Seminar Room (VSR) for multimodal characterization of ADHD symptoms. To test its feasibility, N= 35 healthy participants were immersed into the VSR via a head-mounted display and carried out a VR-embedded continuous performance task (CPT) under varying levels of distractions in two experimental blocks (24 min each). CPT performance, electroencephalography (EEG) measures, and head movements (actigraphy) were simultaneously recorded and analyzed offline. Although CPT performance remained constant throughout the task, head movements increased significantly from Block 1 to Block 2. In addition, EEG theta (4–7 Hz) and beta (13–30 Hz) power was higher during Block 1 than Block 2, and during distractor-present than distractor-absent phases. Moreover, P300 amplitudes were higher during Block 1 than Block 2, and P300 latencies were prolonged in distractor-absent compared with distractor-present phases. Although the paradigm awaits further improvements, this study confirms the general feasibility of the VSR and provides a first step toward a multimodal, ecologically valid, and reliable VR-based adult ADHD assessment

Airborne temperature profiling in the troposphere during daytime by lidar utilizing Rayleigh–Brillouin scattering

The airborne measurement of a temperature profile from 10.5 km down towards ground (about 1.4 km above sea level) during daytime by means of a lidar utilizing Rayleigh-Brillouin (RB) scattering is demonstrated for the first time, to our knowledge. The spectra of the scattered light were measured by tuning the laser (Lambda=354.9 nm) over a 11 GHz frequency range with a step size of 250 MHz while using a Fabry Perot interferometer as a spectral filter. The measurement took 14 min and was conducted over a remote area in Iceland with the ALADIN Airborne Demonstrator on-board the DLR Falcon aircraft. The temperature profile was derived by applying an analytical RB line shape model to the backscatter spectra, which were measured at different altitudes with a vertical resolution of 630 m. A comparison with temperature profiles from radiosonde observations and model temperatures shows reasonable agreement with biases of less than +/-2K. Based on Poisson statistics, the random error of the derived temperatures is estimated to vary between 0.1 K and 0.4 K. The work provides insight into the possible realization of airborne lidar temperature profilers based on RB scattering

Gallium gradients in chalcopyrite thin films: Depth profile analyses of films grown at different temperatures

The following article appeared in Journal of Applied Physics 110.9 (2011): 093509 and may be found at http://scitation.aip.org/content/aip/journal/jap/110/9/10.1063/1.3656986Cu(In,Ga)Se2 films are used as absorber layers in chalcopyrite thin film solar cells. As the gallium concentration in the absorber can be used to control the band gap, there have been many efforts to vary the gallium concentration in depth to gain an optimum balance of light absorption, carrier collection, and recombination at different depths of the absorber film, leading to improved quantum efficiency. In this study, we investigate the effect of the maximum substrate temperature during film growth on the depth dependent gallium concentration. For the in-depth gallium concentration analyses, we use two techniques, covering complementary depth ranges. Angle dependent soft x-ray emission spectroscopy provides access to information depths between 20 and 470 nm, which covers the depth range of the space charge region, where most of the photoexcited carriers are generated. Therefore, this depth range is of particular interest. To complement this investigation we use secondary neutral mass spectrometry, which destructively probes the whole thickness of the absorber (≈2 µm). The two methods show increasingly pronounced gallium and indium gradients with decreasing maximum substrate temperature. The probing of the complementary depth ranges of the absorbers gives a consistent picture of the in-depth gallium distribution, which provides a solid basis for a comprehensive discussion about the effect of a reduced substrate temperature on the formation of gallium gradients in Cu(In,Ga)Se2 and the device performance of the corresponding reference solar cells.The authors acknowledge the support of the European Commission in the framework of the ATHLET-project (Project No. 019670)