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In the quest for more efficient solar thermal systems, accurately determining the thermal emittance of low-emissive materials is crucial in determining the power losses. This paper describes the calorimetric method designed to precisely measure the thermal emittance of Selective Solar Absorbers (SSAs) to be used in High Vacuum Flat Plate Collectors (HVFPCs). The method’s capability is demonstrated through the successful correction of thermal emittance values for copper samples of varying sizes, including dimensions down to 49 cm2. Results highlight the method’s potential to significantly reduce measurement errors associated with small-size and/or low-emittance samples, providing a path forward to improve the design and efficiency of SSAs. This research marks a significant step in advancing solar thermal technology by enabling emittance measurements with a precision better than 0.003, which is essential for the development of high-performance solar thermal absorbers. The method has also been applied to correct the thermal emittance value of SSA measured in previous measurement campaigns, and it allows a better estimation of the SSA efficiency conversion curve.

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.

The management of sustainability transitions often includes action to accelerate technological change. Deployment policies are essential measures to increase the adoption of technologies and spur technological development. However, processes of technological development often follow non-linear pathways, and aligning policy and technological development is challenging. This paper links technological innovation systems (TIS) and their dynamics to the policy feedback framework based on the notion that policies shape future politics. Most significantly, the explicit consideration of TIS processes and progress allows for a more nuanced view of how policy effects turn into feedback and for assessing the co-evolution of TIS and policy over time. This framework is applied to study the case of the German Renewable Energy Act (EEG, 1999–2017). The case study provides evidence that the virtuous cycles of rapid TIS development also increase the odds of growing negative feedback based on rising policy costs, competition within sectors, and increasing technology side effects, opening up windows of opportunity for policy change. Based on these observations, this paper proposes an ideal-typical technology deployment policy life cycle model that describes how TIS, the focal policy, and their context co-evolve in a reciprocal process for the case of the EEG. The discussion sheds light on how deployment policies trigger search processes within the TIS that may encroach national borders to satisfy technology demand. Such search processes fuel political optimism. Rising policy costs and side effects, however, produce policy feedback limiting political leverage. The proposition of a model of how the linkages between policy and technology unfold over time contributes to understanding the timing of policies within sustainability transitions.

This study mainly examines the establishment of wireless networks using hardware chips that stand a chance of improving the communication of smart grid by providing high reliability, low latency as well as data confidentiality. In the suggested setup, a hierarchical architecture together with central gateway, cluster heads and sensor nodes, is exploited to allow data aggregation and thus reduce transmission overhead. Among IoT devices, wireless technologies like Zigbee and LoRa are used to enhance communication quality, thanks to the fault tolerant technique that makes the system more reliable. By studying the theoretical groundwork and the necessary hardware needed in the smart grid communication, the research is intended to identify the most significant obstacles that make current energy transfer networks relatively ineffective.

Dataset supporting publication of manuscript_GCB-B-RA-24-138

Portugal faces water scarcity challenges, yet studies on per-household water consumption are limited. This study aims to address this gap by employing cluster analyses to assess how population trajectories, a previously overlooked aspect, and the regional location influence per-household monthly water consumption across 122 municipalities. Findings highlight higher consumption in the South despite lower prices. Municipalities experiencing population growth and those with long-term population declines show higher per-household water consumption but lower prices. Interestingly, while higher prices correlate with lower consumption, southern municipalities show increased prices without reduced consumption. Clustering reveals slight changes in consumption patterns from 2011 to 2020.

Virtual Synchronous Generator (VSG) control technique is a potent solution to the issue of insufficient inertia in power systems. To address the challenges of low inertia and low output impedance in microgrids, this paper proposes a VSG frequency distributed collaborative secondary control strategy and develops a distributed active power sharing control strategy. Initially, considering the frequency parameter discrepancies among individual VSG, a tracking controller for the VSG frequency reference model is designed based on the heterogeneous multi-agent theory. Subsequently, to alleviate the communication overhead, an integral-type event triggering mechanism is constructed. This mechanism obviates the need for a time synchronization system in VSGs, allowing each unit to rely solely on its internal clock for periodic triggering condition assessments. In contrast to the existing VSG secondary control strategies, this approach ensures the efficacy of the distributed secondary control strategy amidst asynchronous communication networks. Furthermore, the stability of the proposed secondary control strategy is demonstrated using the Lyapunov function in conjunction with the event triggering mechanism. Ultimately, an island microgrid system is simulated on the MATLAB/simulink platform, and the simulation results verify the feasibility and effectiveness of the proposed control strategy.

AbstractThe summer of 2018 was characterized by prolonged heatwaves over Northern Europe, associated with persistent atmospheric blocking, and an unusually northward jet stream location over Scandinavia. Whilst event attribution studies tend to focus on the change in probability or magnitude of the extreme temperatures themselves, we provide context to these studies by examining whether there are human induced trends in the atmospheric circulation that might affect the likelihood of similar extreme circulation patterns and associated heat waves occurring in the future. We examine trends and variability in summer jet latitude, blocking frequency and overall circulation pattern over the Scandinavian sector in a variety of reanalyses and climate model ensembles. Both the number of blocked days, and the average jet location for summer 2018 were unprecedented in the reanalyses, and rare in climate model simulations. We found no robust evidence of past or future externally forced changes in summer blocking frequency over Scandinavia in model simulations, whilst trends in circulation analogs were also largely insignificant. Trends in jet latitude were dependent on the time period examined, models included and other analysis choices. Overall, we found no robust evidence for systematic trends in average or extreme years toward Summer 2018‐like conditions for any of the three indices, nor in the frequency of co‐occurring extreme northward jet latitude and high blocking frequency. We conclude that Summer 2018s circulation can likely be explained by internal atmospheric variability.