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Degradation issues correlated to microstructural changes are the main obstacles to solid oxide fuel cell and electrolyser applications, making their identification and understanding fundamental steps. Coupling experimental activities with modelling, this work analyses the state-of-the-art Ni-YSZ (Yttria-Stabilized Zirconia)/YSZ/CGO (Cerium Gadolinium Oxide)/LSCF (Lanthanum Strontium Cobalt Ferrite)-CGO-based cell after 1000 h of galvanostatic electrolysis operation at fixed temperature and high steam composition in the inlet gas. Following a multiscale approach, the system behaviour is characterized through electrochemical impedance spectra and polarization curves as well as studying microstructure evolution, with a focus on Ni-cermet functional layer in view of Ni instability detected as the main degradation cause. A comparison with a cell consisting of the same initial geometrical structure and materials but aged in fuel cell mode allows to highlight the influence of operating mode and parameters on Ni-YSZ microstructure. Ni particle size and phase fraction variations experimentally observed on the electrode surface are correlated to water content and applied polarization simulated local values. Ni uneven distribution at the electrolyte interface and particle coarsening, above all, lead to an increase in polarization loss under electrolysis and fuel cell mode, respectively, since both penalise the charge transfer reaction and migration.

Abstract The phonon-glass electron-crystal paradigm has guided thermoelectric research in recent years. However, the inherent conflict between atomic disorder reducing phonon conduction, and the order required to maintain high electron mobility, creates a significant challenge in material design, which has driven innovation in nanostructuring and composite materials. Here, vertically aligned nanocomposites (VANs) composed of self-assembled metallic La0.7Sr0.3MnO3 (LSMO) nanopillars in a surrounding ZnO matrix are investigated for controllable thermal conductivity. Tuning of the crystal orientation of the substrate controls the epitaxial alignment of the LSMO and ZnO phases along the horizontal and vertical interfaces. The VAN films on (111)-oriented STO substrates exhibit an increased power factor of 0.52 μW·cm−1·K−2 at 600 °C beyond ZnO films of 0.15 μW·cm−1·K−2. Detailed characterization and modeling of the thermal conductivity demonstrates a reduction of about 75% as well as anisotropic behavior for the VAN films with out-of-plane and in-plane thermal conductivities of respectively 9.2 and 1.5 W·m−1·K−1, in strong contrast to the isotropic behavior in ZnO films with a thermal conductivity of 38 W·m−1·K−1. These results show the promising strategy of VAN thin films with a nanopillar-matrix architecture to scatter phonons and to enhance the thermoelectric performance.

Abstract. Wake losses are a significant source of inefficiencies in wind farm arrays, hindering the development of high-energy density wind farms offshore. Studies have demonstrated the potential of vertical-axis wind turbines (VAWTs) to achieve high-energy density configurations due to their increased rate of wake recovery compared to their horizontal-axis counterparts. Recent works have demonstrated a wake control technique for VAWTs that utilizes blade pitch to accelerate the wake recovery, hereinafter referred to as the "vortex-generator" method. The present work is an experimental investigation of the wake topology using this control technique for the novel X-Rotor VAWT. The time-averaged wake topology of the X-rotor has been measured by stereoscopic particle-image velocimetry at three fixed-pitch conditions of the top blades, namely a pitch-in, pitch-out, and a baseline case with no pitch applied. The results demonstrate the wake recovery mechanism linked to the streamwise vorticity system of the rotor and the mechanisms that lead to a streamwise momentum recovery, where the pitched-in case injects high momentum flow from above the rotor while ejecting the wake from the sides. In contrast, the pitched-out case operates in a mirrored fashion, with high momentum flow injected into the wake from the sides while low-momentum flow is ejected out axially above the rotor. These modes of operation demonstrate a significant increase in the available power for hypothetical downstream turbines, reaching as high as a factor of 2.2 two rotor diameters downstream compared to the baseline case. The pitched-in case exhibits a higher rate of momentum recovery in the wake compared to the pitch-out configuration.

CONTEXT: Flanders, a densely populated region in Belgium, faces challenges in balancing agricultural production with renewable energy targets. Agrivoltaic systems combine solar energy and agricultural activity on the same field and can increase land productivity while simultaneously expanding the share of renewables. However, its potential and implications for the region is geographically complex. OBJECTIVE: This research aims to assess the suitability of Flanders' 658,000 ha agricultural land for agrivoltaic systems, using a geographical multi criteria decision analysis (MCDA), considering environmental, technical, agronomic, and cultural criteria to optimize land use for simultaneous food and energy production. METHODS: We describe a Geographic information system Multiple-criteria decision analysis (GIS-MCDA) using QGis-software. Expert stakeholder input was incorporated by applying the pairwise comparison method from the analytical hierarchical process (AHP). Criterion weights are applied to seven classifiers: irradiance, soil suitability, slope, orientation (aspect), crop type, flood risk and distance to roads/grid. Areas with particular societal, ecological, economic, and historical importance are excluded. The resulting scores are then placed in their agronomic and energy context. RESULTS AND CONCLUSION: Our analysis indicates that 60.4 % of Flanders' farmland is well suited for agrivoltaic development, and that 9 % of farmland under AV would suffice to meet future energy targets in combination with rooftop PV. After our analysis, 11.5 % of total agricultural land was classified as less suitable, 28.74 % as somewhat suitable, 19.40 % as suitable and 12.22 % as very suitable. SIGNIFICANCE: Transitioning away from fossil fuels requires a multi-facetted approach. Agrivoltaic systems can contribute to this shift, opening up additional land without significantly compromising farm revenue. This study presents insights into the feasibility and geographic potential of agrivoltaic systems in densely populated regions with intensive agriculture like Flanders and can serve as a base for future discussion regarding dual land use planning decisions locally and abroad. We would like to thank all participants of the survey, as well as Marleen Gysen and Tom Schaeken (Boerenbond) for organizing the dissemination events making it possible to reach the appropriate expert audience. Special thanks also to Gabriele Torma (Aarhus University) for helping set up the survey. Also, thanks to Wim Clymans (VITO) for providing feedback on the draft manuscript and Andreas Harlander (Krinner GMBH) for the use of their photo. This work was supported by the European Union’s Horizon 2020 research and innovation programme project “HyPErFarm” [grant number 101000828]; a Flanders Innovation and Entrepreneurship (VLAIO) “TETRA” grant project “Agrivoltaics” [grant number HBC.2019.2049]; and a VLAIO LA-traject grant “Agri-PV” [grant number HBC.2022.0920]. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

This work explores the effectiveness of explainable artificial intelligence in mapping solar photovoltaic power outputs based on weather data, focusing on short-term mappings. We analyzed the impact values provided by the Shapley additive explanation method when applied to two algorithms designed for tabular data—XGBoost and TabNet—and conducted a comprehensive evaluation of the overall model and across seasons. Our findings revealed that the impact of selected features remained relatively consistent throughout the year, underscoring their uniformity across seasons. Additionally, we propose a feature selection methodology utilizing the explanation values to produce more efficient models, by reducing data requirements while maintaining performance within a threshold of the original model. The effectiveness of the proposed methodology was demonstrated through its application to a residential dataset in Madeira, Portugal, augmented with weather data sourced from SolCast.

This comprehensive review examines the multifaceted relationships involving demand response aggregators within the electricity sector. Focusing on interactions with stakeholders such as electricity suppliers, system operators, distributed energy resources, and flexibility-requesting parties, the paper delves into critical aspects including market dynamics, compensation models, balancing responsibilities, and contractual frameworks.

In dieser Arbeit wird die fortgeschrittene Pinch-Analyse (im Folgenden PA) als Instrument zur Optimierung der Energienutzung und der Einführung erneuerbarer Energieressourcen in industriellen Prozessen untersucht, um das Problem der Nachhaltigkeit und der Dekarbonisierung industrieller Energiesysteme zu lösen. In dieser Hinsicht konzentriert sich die Forschung auf die thermodynamische Energieeffizienz, bei der die Reduzierung der Treibhausgasemissionen (im Folgenden THG) berücksichtigt wird. Aus diesem Grund orientiert sich diese Forschung an einigen Bestimmungen des Pariser Abkommens oder an europäischen Green-Deal-Initiativen. Die Definition des Anwendungsfalls konzentriert sich auf eine systematische Vorgehensweise, die unter anderem eine Literaturrecherche, eine Datenerhebung und eine thermodynamische Analyse mit Hilfe der Pinch-Analyse umfasst. Zu den wichtigsten Methoden gehören die Konstruktion und Interpretation von zusammengesetzten und verschobenen zusammengesetzten Kurven sowie der Grand Composite Curve (GCC) zur Bewertung und Verbesserung der thermodynamischen Effizienz von Prozessen. Der Anwendungsfall bietet eine praktische Grundlage für die Anwendung und Validierung der PA-Methodik. Die Ergebnisse zeigen erhebliche Möglichkeiten für die Wärmerückgewinnung und die Optimierung der internen Energieströme auf, einmal unter Berücksichtigung aller theoretischen Einschränkungen der Pinch-Analyse und einmal als innovativer Ansatz, der die Grenzen der PA überwindet. Die Fallstudie veranschaulicht die Integration von Technologien wie Wärmetauschern, Wärmepumpen und solarthermischen Systemen, um die Abhängigkeit von fossilen Brennstoffen zu verringern und gleichzeitig den Heiz- und Kühlbedarf zu decken. Die innerbetriebliche Nutzung erneuerbarer Energiequellen wie der Solarthermie kann als eine weitere Form der Wärme in den Prozess integriert werden, was zu besseren Möglichkeiten für einen nachhaltigen industriellen Betrieb führt. Sie verbessert die praktische Anwendung in dieser Studie von PA, indem sie reale Einschränkungen berücksichtigt und gleichzeitig zukunftsorientierte Lösungen zur Energieoptimierung untersucht. Ihr wichtigster Beitrag besteht darin, die Aufmerksamkeit auf die Fragen der industriellen Energieeffizienz und der potenziellen wirtschaftlichen Einsparungen für Industrien zu lenken, die versuchen, ein Gleichgewicht zwischen konkurrierenden wirtschaftlichen und ökologischen Belangen herzustellen. This thesis investigates the advanced Pinch Analysis (hereafter PA) as a tool for optimizing the use of energy and adoption of renewable energy resources in industrial processes, which aims to address the issue of sustainability and the concern of industrial energy systems needing decarbonization the most. In this regard, the research focuses on thermodynamic energy efficiency during which reduction of Greenhouse-Gas (hereafter GHG) emissions is considered. That is why this research aligns itself with some provisions of the Paris Agreement or European Green Deal initiatives. The use case definition focuses on a systematic way which involves among others a literature review, data collection, and thermodynamic analysis using Pinch Analysis. Key methods involve constructing and interpreting composite and shifted composite curves as well as the Grand Composite Curve (GCC) to evaluate and improve the thermodynamic efficiency of processes. The use case provides a practical basis for applying and validating the PA methodology. The results reveal significant opportunities for heat recovery and the optimization of internal energy flows, once following all the theoretical limitations of the Pinch Analysis, and once an innovative approach, defying the limitations of the PA. The case study illustrates the integration of technologies such as heat exchangers, heat pumps, and solar thermal systems to de-crease dependence on fossil fuels while meeting heating and cooling needs. In-plant utilization of renewable energy sources such as solar thermal energy can be integrated into the process as another form of heat, which is useful in giving better possibilities of sustainable industrial operation. It enhances practical application in this study of PA by considering real-world constraints while investigating forward-looking solutions for optimizing energy. Its principal contribution has been to draw attention to the issues of industrial energy efficiency and potential economic savings for industries attempting to balance competing economic and environmental concerns.

The European Union's goal of achieving climate neutrality by 2050, outlined in the European Green Deal, is supported by numerous studies providing insights into pathways and emission reduction strategies in the energy sectors. However, model comparisons of such pathways are less common due to the complex nature of climate and energy modelling. Our study brings together integrated assessment models and energy system models under a common framework to develop EU policy scenarios: a Current Trends scenario reflecting existing policies and trends and a Climate Neutrality scenario aligned with the EU's emission reduction target. Both scenarios project reduced final energy consumption by 2050, driven by increased electrification and decreased fossil fuel usage. Electricity consumption increases driven by electrification despite the improved efficiency of electrified technologies. Models align on a shift toward renewables but diverge in technology and fuel choices, reflecting various approaches to reach net-zero energy systems. Furthermore, trade-offs between energy demand and supply mitigation strategies, as well as between renewable energy, e-fuels, and CCS technologies are identified. Considering these model variations, our study highlights the importance of consistent model comparison to offer reliable recommendations to policymakers and stakeholders. We conclude that model diversity is a valuable asset when used sensibly. ISSN:0360-5442 ISSN:1873-6785 Energy, 319