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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.

The study compares the performance parameters of an Automated Guided Vehicle (AGV) equipped with optical navigation, focusing on two solutions: one utilizing reflective optocouplers and the other employing a camera. These components, commonly used in AGV optical navigation systems, differ in factors such as cost and the sophistication of control methods. The primary objective of the research was to evaluate the performance criteria of the analyzed optical navigation methods, with particular attention paid to electricity consumption, power profiles during specific transit tasks, and total transit time. The analysis also investigated two potential installation locations for the reflective optocouplers and the camera on the vehicle. The results indicate that the camera-based optical navigation method is more efficient. Specifically, the average energy consumption was approximately 26% lower when using the camera compared to the reflective optocouplers. Furthermore, the study revealed that the location of the camera had minimal influence on the vehicle’s energy consumption, whereas the location of the reflective optocouplers significantly affected energy usage.

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.