• Energy Research
• 2021-2025close
• Open Access close
• Restricted close
• DK close

AbstractEuropean climate is associated with variability and changes in the mid-latitude atmospheric circulation. In this study, we aim to investigate potential future change in circulation over Europe by using the EURO-CORDEX regional climate projections at 0.11° grid mesh. In particular, we analyze future change in 500-hPa geopotential height (Gph), 500-hPa wind speed and mean sea level pressure (MSLP) addressing different warming levels of 1 °C, 2 °C and 3 °C, respectively. Simple scaling with the global mean temperature change is applied to the regional climate projections for monthly mean 500-hPa Gph and 500-hPa wind speed. Results from the ensemble mean of individual models show a robust increase in 500-hPa Gph and MSLP in winter over Mediterranean and Central Europe, indicating an intensification of anticyclonic circulation. This circulation change emerges robustly in most simulations within the coming decade. There are also enhanced westerlies which transport warm and moist air to the Mediterranean and Central Europe in winter and spring. It is also clear that, models showing different responses to circulation depend very much on the global climate model ensemble member in which they are nested. For all seasons, particularly autumn, the ensemble mean is much more correlated with the end of the century than most of the individual models. In general, the emergence of a scaled pattern appears rather quickly.

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.

AbstractMicrobial carbon (C) use efficiency (CUE) delineates the proportion of organic C used by microorganisms for anabolism and ultimately influences the amount of C sequestered in soils. However, the key factors controlling CUE remain enigmatic, leading to considerable uncertainty in understanding soil C retention and predicting its responses to global change factors. Here, we investigate the global patterns of CUE estimate by stoichiometric modeling in surface soils of natural ecosystems, and examine its associations with temperature, precipitation, plant‐derived C and soil nutrient availability. We found that CUE is determined by the most limiting resource among these four basic environmental resources within specific climate zones (i.e., tropical, temperate, arid, and cold zones). Higher CUE is common in arid and cold zones and corresponds to limitations in temperature, water, and plant‐derived C input, while lower CUE is observed in tropical and temperate zones with widespread limitation of nutrients (e.g., nitrogen or phosphorus) in soil. The contrasting resource limitations among climate zones led to an apparent increase in CUE with increasing latitude. The resource‐specific dependence of CUE implies that soils in high latitudes with arid and cold environments may retain less organic C in the future, as warming and increased precipitation can reduce CUE. In contrast, oligotrophic soils in low latitudes may increase organic C retention, as CUE could be increased with concurrent anthropogenic nutrient inputs. The findings underscore the importance of resource limitations for CUE and suggest asymmetric responses of organic C retention in soils across latitudes to global change factors.

Aligned with Denmark’s growing smart energy networks encompassing district heating and electricity grids and in harmony with the country’s ambitious energy and environmental objectives, this study aims to elevate the investigation from individual buildings to consider districts and cities. In pursuit of this objective, a case study of an Odense district in Denmark was considered for modeling, simulation, and energy performance improvement. The selected residential area was modeled using City Energy Analyst, an open-source urban scale modeling tool, accounting for different building attributes as well as the particulars of energy networks and supply systems. The validation of a baseline scenario is predicated upon real-world data collected on-site to serve as the benchmark for exploring and evaluating various scenarios and measures for enhancing energy efficiency. Consequentially, eight distinct energy enhancement packages were designed, modeled, and simulated individually. The results were analyzed, and it was shown that an energy improvement package consisting of retrofitting buildings’ constructions, indoor thermal comfort setpoint management, heating system upgrade, photovoltaic-thermal unit installation, and heat pump integration, along with a seasonal energy storage system, is capable of enhancing the overall energy efficiency quotient of the area, establishing a positive energy district with an excess in heat and electricity production.

Abstract Tropical mountain cloud forests (TMCF) harbour a high bryophyte (mosses and liverworts) biomass and diversity. Furthermore, the high air humidity makes these forests well suited for bryophyte‐associated nitrogen (N2) fixation by cyanobacteria, providing a potentially important source of N input to the ecosystem. However, few studies have assessed bryophyte‐associated N input in these ecosystems, and these have focused on epiphytic bryophytes, whereas abundant ground‐covering bryophytes have not been included. In this study, we quantified N2 fixation rates associated with bryophytes, focusing on ground‐covering mosses in a neotropical mountain cloud forest. Furthermore, we identified the effects of climate change (higher temperature 10 vs. 20° and lower bryophyte moisture level 50% vs. 100%) on N2 fixation across bryophyte species and groups (mosses and liverworts). Nitrogen fixation rates associated with ground‐covering moss species were up to 2 kg N ha−1 year−1, which is comparable to other N inputs (e.g. N deposition) in tropical cloud forests. Furthermore, changes in temperature showed little effect on N2 fixation, but low moisture levels significantly suppressed N2 fixation activity. We found low N2 fixation activity associated with the investigated liverworts. Our results demonstrate the importance of ground‐covering, moss‐associated N2 fixation as a N source in tropical cloud forests and suggest that predicted future declines in precipitation in these systems will reduce N inputs from bryophyte‐associated cyanobacteria. Read the free Plain Language Summary for this article on the Journal blog.

Hybrid electric ships powered by diesel generators and batteries are the main configuration for shipboard microgrids (SMGs) in the current maritime industry. Extensive studies have been conducted for the hybrid operation mode, whereas the all-electric operation mode and the switching between the aforementioned two modes in a system with multiple generators and batteries have not been tested. In this paper, a coordinated approach for a hybrid electric ship is proposed, where two operation modes have been simultaneously considered. More specifically, for achieving an efficient operation with reduced generator wear losses, the governor-less diesel-engine-driven generators have been adopted in the study. According to the practical operation conditions, two operation modes, the all-electric and hybrid modes, are preset. Based on these, the coordination of the generators acting as the main power sources and batteries regulating the power flow and improving the generator efficiency is studied. The governor-less diesel generators are regulated to inject the rated power in order to maximize the generator efficiency, while the DC bus voltage is regulated by DC/DC converters. For the benefit of the overall lifespan of battery banks, power sharing during charging and discharging states have been realized by the state of charge (SoC)-based adaptive droop regulator. For the test of two operation modes, as well as the mode switching, a simulation assessment in a 1 kV DC SMG has been conducted. The simulation results show that the DC bus voltage can be controlled well, and that the power sharing among batteries follows the design. Additionally, smooth transients can be observed during mode switching when the proposed control scheme is applied.