Power transformers are key grid assets whose reliability depends on effective heat rejection. Oil Directed Air Natural (ODAN) radiator banks rely on buoyancy driven airflow and are therefore sensitive to hot ambient conditions. This study validates a conjugate computational fluid dynamics (CFD) model of an industrial ODAN radiator bank against manufacturer tests, then uses it to quantify hot ambient performance losses and to evaluate passive chimney extensions. The model predicts total heat dissipation within 1.8% and a weighted oil outlet temperature within 0.1% of measurements and shows that surface to surface radiation contributes about 14% of the total heat rejection under natural convection. Parametric simulations over ambient temperatures from 20 to 50 degrees C and oil inlet temperatures from 54.8 to 105 degrees C show a strong monotonic reduction in cooling capacity with ambient temperature, with losses of about 25 - 35% per 10 degrees C increase at fixed oil inlet conditions. Straight chimneys increase buoyancy draft and raise cooling capacity approximately linearly with height, reaching a 16.2% gain for a 5 m extension. Convergent, deflector equipped, and unified chimney variants reduce performance because added minor losses and recirculation weaken plume coherence. A first order cost screening indicates that conventional radiator geometry upgrades provide greater thermal gains per unit cost than stainless steel chimneys under the assessed assumptions. These results provide design guidance for improving the robustness of ODAN passive cooling under hot ambient conditions.

The ongoing pursuit of enhanced efficiency and sustainability in power transformer cooling systems has spurred extensive research into the properties and performance of insulating fluids. This review explores the evolution of transformer cooling technologies, focusing on traditional mineral oils and the emerging roles of alternative fluids, such as natural and synthetic esters, and nanofluids. Mineral oils, though widely used, degrade over time, leading to a reduction in breakdown voltage (BDV) from 46 kV to 30 kV, exhibiting low fire resistance. Natural and synthetic esters provide improved biodegradability, fire safety but have higher viscosities—potentially limiting convective cooling. Nanofluids, have demonstrated BDV enhancements of up to 47.8%, reaching 88.7 kV in optimised formulations, alongside increases in partial discharge inception voltage (PDIV) of 20–23%. Additionally, thermal conductivity improvements of 5–20% contribute to enhanced heat dissipation. Moreover, it addresses challenges such as nanoparticle agglomeration, sedimentation, ageing, and compatibility with transformer materials. The analysis provides critical insights into the trade-offs between technical performance and economic feasibility. Concluding with an outlook on future research directions, the review identifies key parameters across various categories, establishing a roadmap for nanofluid integration with existing transformer systems.

Efficient cooling technologies for power transformers are critical to modern power systems, ensuring reliability, performance, and AN extended lifespan. This review systematically analyses advancements, challenges, and opportunities in cooling systems for power transformers. Oil-immersed transformers, widely used due to their superior insulation and effective cooling, require efficient thermal management to prevent overheating and ensure operational stability. This review evaluates key cooling strategies across oil-natural air-natural (ONAN), oil-natural air-forced (ONAF), oil-directed air-forced (ODAF), and oil-forced air-forced (OFAF) systems. It highlights innovations in radiator design, such as top-mounted radiators and chimney caps, and explores sustainable alternatives, including biodegradable esters, nanofluids, and hybrid ventilation methods. Advanced computational tools like Computational Fluid Dynamics (CFD) and artificial intelligence (AI), particularly neural networks, are identified as transformative for optimising cooling performance, predicting thermal behaviour, and enabling real-time monitoring. Despite progresses, challenges persist in radiator optimisation, airflow dynamics, and scalability of innovative cooling methods. By offering a comprehensive review and identifying critical areas for improvement, this study provides a foundation for developing cost-effective, reliable, and environmentally sustainable cooling systems, aligning with the growing demand for efficient energy infrastructure.

This study evaluates the impact of climate change on the energy performance of residential buildings across Portugal’s diverse climatic regions, providing a representative reference for Southern European contexts. Dynamic energy simulations using EnergyPlus were conducted for standardised residential building models in five cities: Bragança, Porto, Lisbon, Évora, and Faro. Three climate scenarios were analysed: present-day conditions (TMY2021), the current regulatory scenario (LNEG-EPW), and a projected mid-century scenario (CCW-EPW). Results indicate substantial regional variations, with significant increases in cooling demands and corresponding reductions in heating needs, exposing limitations in the regulatory climate files currently used in energy certification processes. These findings emphasise the critical need to incorporate predictive climatic scenarios into building design standards and energy policies. Adopting such an approach will enhance residential building resilience, ensure thermal comfort, reduce energy consumption, and contribute to sustainable development goals. These insights offer practical guidance for policymakers, urban planners, architects, and engineers aiming to effectively adapt residential buildings to anticipated climatic shifts, facilitating proactive and informed decision-making to address future energy challenges.

Disposing of end-of-life wind turbine blades has become a pressing environmental concern due to the increasing repowering of wind turbines, resulting in significant waste. This study explores the potential of reusing shredded composite (SC) derived from recycling these blades for new building components. The SC underwent a thorough characterisation, including evaluating essential performance requirements as a building insulation material, such as thermal conductivity, acoustic absorption, and flammability classification, following established procedures and standard specifications to ensure reliable and standardised results. The SC outperforms traditional materials regarding sound absorption properties, with peak Noise Reduction Coefficient (NRC) values reaching 0.65. Additionally, it demonstrates effective sound transmission loss, with a peak value of 35.7 dB at 1000 Hz. However, the SC has limitations regarding flammability classification due to the presence of resin. The study examines the thermal conductivity of SC in maximum fibre length (MFL) of 2 mm and 10 mm, with the latter showing lower conductivity. These findings highlight the value of reusing and repurposing materials for creating sustainable building components and practices, supporting circular economy principles. They also underscore the importance of addressing the large-scale disposal of waste materials through their effective reuse in the construction industry.

The rapid growth of the wind energy industry has resulted in a significant increase in Wind Turbine Blade (WTB) waste, posing challenges for recycling due to the composite materials used in their construction. Several proposed techniques, including mechanical, thermal, and chemical processes, have been considered for wind-blade recycling, but determining the most effective approach remains a critical issue. This study presents the first comprehensive systematic review of available wind-blade recycling processes, evaluating their economic, technical, and environmental performance. Additionally, we consider the physical and mechanical properties of the recycled materials, which can aid in identifying potential markets for these materials. Among the various recycling technologies, microwave pyrolysis emerges as the most promising technique for recycling large quantities of WTB, despite some challenges and uncertainties surrounding its effectiveness and feasibility at an industrial scale. However, the optimal recycling technique for WTB will depend on multiple factors, including the blade material, the desired environmental impact, and the economic feasibility of the process. Based on this review, mechanical recycling appears to be more energy-efficient, while the fluidised bed recycling process demonstrates a lower primary energy demand, global warming potential, and power consumption. These findings provide valuable guidance for decision-makers in the wind energy industry to develop effective waste management strategies and plans for sustainable wind energy development. Addressing WTB waste and implementing efficient recycling techniques will be critical in mitigating environmental impacts and promoting sustainability in the renewable energy sector as the wind energy industry grows.

Recent extreme wildfire events (EWE) in Australia, the United States of America (USA), Greece and Portugal highlighted the seriousness of wildfire smoke impacts on society [...]

In the last decades, numerous large forest fires have been recorded in Portugal. On 15 and 16 October 2017, seven extreme wildfires events (EWEs) took place in the central region of Portugal. Aiming to contribute to the assessment of the smoke impact of these EWEs, this study estimates their atmospheric emissions using a bottom-up approach with high spatial and temporal resolution. To this end, fire data were used, such as ignition location and time, propagation, burned area, and fuel load and emission factors according to forest species. A particular fire – EWE in Lousã with a high fuel load – emitted ~50% of the sum of the emissions of the six other case studies. The spatial distribution of the EWE emissions indicates that fuel load is an important component of emissions estimation. The obtained results were compared with remote sensing data, showing good agreement in terms of total values. During these EWEs, particulate matter and carbon monoxide emissions were higher than Portuguese anthropogenic emissions in 2017. This approach contributes to the state of the art on forest fire emissions, reducing uncertainty and obtaining the best possible and detailed quantification of the temporal and spatial variability of EWE emissions.

Smoke inhalation poses a serious health threat to firefighters (FFs), with potential effects including respiratory and cardiac disorders. In this work, environmental and physiological data were collected from FFs, during experimental fires performed in 2015 and 2019. Extending a previous work, which allowed us to conclude that changes in heart rate (HR) were associated with alterations in the inhalation of carbon monoxide (CO), we performed a HR analysis according to different levels of CO exposure during firefighting based on data collected from three FFs. Based on HR collected and on CO occupational exposure standards (OES), we propose a classifier to identify CO exposure levels through the HR measured values. An ensemble of 100 bagged classification trees was used and the classification of CO levels obtained an overall accuracy of 91.9%. The classification can be performed in real-time and can be embedded in a decision fire-fighting support system. This classification of FF' exposure to critical CO levels, through minimally-invasive monitored HR, opens the possibility to identify hazardous situations, preventing and avoiding possible severe problems in FF' health due to inhaled pollutants. The obtained results also show the importance of future studies on the relevance and influence of the exposure and inhalation of pollutants on the FF' health, especially in what refers to hazardous levels of toxic air pollutants.

Emission inventories are an essential tool for harbour authorities to assess the impacts of harbour-related activities and to assess the effectiveness of mitigation measures. In this paper, two bottom-up methodologies (EMEP/EEA and US/SCG) are applied to the Port of Leixões, Portugal, to develop an emission inventory for harbour-related activities, accounting for both the emissions from shipping and the cargo handling equipment. Emission estimates obtained from the two methodologies are compared and discussed. Regarding shipping emissions, the main disparities between the two methodologies arise from the differences in emission factors and application (or not) of fuel correction factors. Among the considered pollutants, EMEP/EEA methodology estimates higher total emissions (for all types of ship combined) of SO X , NO X , VOC, PM 2.5 , PM 10 , CH 4 , HC, CO and CO 2 (up to 46%), and lower emission of only N 2 O (up to 7%), comparing to US/SCG. Regarding CHE emissions, only EMEP/EEA methodology considers the deterioration factors adjustment, while the fuel correction factor is only considered for US/SCG methodology. Different emission factors also contribute to the observed differences in CHE emissions estimates, leading to higher total emissions (for all CHE combined) of NO X , CO, N 2 O, PM 2.5 , PM 10 , SO X and CO 2 (up to 85%), and lower emission of only CH 4 (264%), comparing to US/SCG. This paper provides a highly relevant approach to estimate CHE-related emissions in European ports and highlights the importance for a standardized methodology to estimate emissions from harbour activities, contributing not only to improve the scientific knowledge but also to provide support to harbour authorities, regarding the quantification of harbour’s environmental performance and the definition of mitigation measures.

The continuous world population growth, followed by current globalization levels, raises concerns towards sustainable development, including the sustainability of organizations. In recent decades, organizations have been increasing their commitment to sustainability. In particular, port organizations are aware of their most critical economic, environmental and social impacts, due to the continuous growth of the sector. Performance indicators are an important tool to assess the environmental performance of a port. In this paper, we aim to recognize the role of these indicators on the sustainability assessment of port organizations. For that purpose, we apply the benchmarking technique to compare the performance of distinct European seaports using environmental performance indicators from the Global Reporting Initiative consolidated guidelines. The indicators most representative of port activities are established and quantified considering the available data for the period between 2008 and 2017. The difficulties associated with the application of the benchmarking technique paves the way for guidelines towards the establishment of a common framework for reporting environmental indicators for the specific case of port organizations. Based on the benchmarking outcomes, we apply the environmental performance indicators to the Port of Aveiro to assess their effectiveness while suggesting adjustments to the existing indicators which are better suited for port activities. The outcomes of this study will provide port organizations with a common framework to report environ mental sustainability, thus allowing for a better comparison of their environmental performance.

Atmospheric emissions related to harbor-related activities can significantly contribute to air pollution of coastal urban areas and so, could have implications to the citizens’ health that live in those areas. Of great concern is the local impact of the emissions that are generated while ships are at berth, since not all types of ships switch off the main engines. This paper intends to investigate the influence of the stack configuration for generic cargo ships on the exhaust smoke dispersion, using the Port of Leixões as a case study and a series of wind tunnel experiments with support of Particle Image Velocimetry (PIV) technique. For that, different configurations of the stack of a cargo ship (in terms of height, geometry and diameter) were simulated under the typical wind conditions of the study area. The PIV results indicate negligible differences between the medium and long stack height, with the short stack height presenting a strong impact on the flow field around the stack. For the short stack height, the flow field is not only disturbed by the stack, but also by the cargo ship bridge, with both obstacles promoting disturbances on the flow field and creating a large wake turbulence effect, which is important for the downwash phenomena. Regarding the effects linked with two distinct geometries (straight or curved), the results show that the straight chimney led to higher perturbation of wind field when compared with the curved geometry. The curved stack presents an increase of vorticity, indicating the generation of more turbulent structures. The PIV results also confirmed that higher wind velocity at the inlet conducts to higher vorticity levels, as well as a higher number of Kelvin–Helmholtz structures. For distinct wind conditions the PIV measurements point out different patterns, indicating the northern wind direction as the most favorable condition for the exposure of dock workers to pollutants. Overall, the results showed that a ship stack with a curved end, medium length and smaller diameter has the capability to promote the behaviors in the flow that are coherent with increased pollutant dispersion.

The complexity of the built environment plays an essential role on the local urban microclimate. Therefore, this work aims to assess the impact of buildings arrangement on the overall turbulent flow dynamics. This study is conducted for the neighborhood of an open auditorium located in an urban area. A set of experiments were accomplished using a wind tunnel, together with a set of Computational Fluid Dynamics (CFD) simulations. Both the experiments and the CFD simulations were carried out for a set of meteorological conditions identified as prevailing in the auditorium area. The physical and numerical approaches were used to assess the wind patterns for the reference scenario. Furthermore, a series of mitigation measures was simulated to evaluate their effectiveness in reducing the wind speed at pedestrian level in the neighborhood. The overall results emphasize the role of the mitigation measures to reduce wind speed and potentially improve pedestrian wind comfort levels in the auditorium. The originality of this paper relies on the design and test of the set of proposed mitigation measures, through the combination of complementary tools, as well as the expertise of distinct practitioners, and their insights regarding their effectiveness.

<p>The Portuguese ASHMOB project (CENTRO-01-0145-FEDER-029351) is addressing the overall lack of knowledge on the mobilization of wildfire ash with time since fire. More specifically, ASHMOB is looking into the lateral transport of wildfire ash by water as well as wind erosion. ASHMOB involves a combined measurement-modeling approach comprising five phases: (i) wildfire ash collection and characterization; (ii) wind tunnel experiments of ash mobilization by wind erosion; (iii) hydraulic laboratory experiments of ash mobilization by rainfall splash, run-on and their combination; (iv) adjusting selected wind and water erosion models to accommodate erosion of wildfire ash; (v) validating the adjusted models by field measurements in a recently burnt area.  The current presentation concerns the second phase and, in particular, wind tunnel experiments aiming to assess the influence of water content on the post-fire ash mobilization. The experiments were performed in the wind tunnel of the Atmosphere Aerodynamics Laboratory of Aveiro University’s Department of Environment and Planning, which is an open-circuit wind tunnel with 13 m long and a test section of 6.5x1.5x1.0 m (LxWxH), often used for physical modelling of urban flows and air quality. For these experiments, wildfire ash was used from three different land cover types, i.e. Maritime Pine and Eucalypt forest plantations and Strawberry tree woodlands (or, more concretely, woodland patches). These ashes were collected as soon as possible after three wildfires that occurred during the summer of 2019 in central Portugal, typically within 2 weeks. The pine, strawberry tree and eucalypt ashes were collected following wildfires in july in Vila de Rei, august in Fátima and september in Albergaria-a-Velha, respectively. The experiments involved one specific ash load of 10 mm, based on findings of earlier experiment with varying ash loads, and ash-to-water ratio of 1:0, 1:0.25, 1:0.5, 1:0.75, 1:1, 1:1.5 and 1:2 (w<sub>ash</sub>/w<sub>water</sub>) at the start of the experiments. Ash mobilization with stepwise increasing wind speeds up till 9 m.s<sup>-1</sup> was measured continuously using a measurement scale linked to a computer and was also filmed from above using a Go-Pro video camera. For each combination of ash type and ash-to-water ratio, 5 replicate experiments were run. Preliminary analysis of the obtained results revealed a clear role of water content in the mobilization by wind of all three types of wildfire ash, with marked increased shear velocity with increasing ash-to-water ratio. At the same time, shear velocity also differed markedly between the woodland types, with consistently lower shear velocity for pine ash than for eucalypt as well as strawberry tree ash at the different ash-to-water ratios.</p>

Several harbour activities cause negative environmental impacts in the harbours’ surrounding areas, namely the degradation of air quality. This paper intends to comprehensively review the status of the air quality measured in harbour areas. The published studies show a limited number of available air quality monitoring data in harbours areas, mostly located in Europe (71%). Measured concentrations of the main air pollutants were compiled and intercompared, for different countries worldwide allowing a large spatial representativeness. The higher NO2 and PM10 concentrations were found in Europe - ranging between 12 and 107 μg/m3 and 2–50 μg/m3, respectively, while the higher concentrations of PM2.5 were found in Asia (25–70 μg/m3). In addition, the lower levels of SO2 monitored in recent years suggest that current mitigation strategies adopted across Europe were very efficient in promoting the reduction of SO2 concentrations.

This work aimed to: (i) assess the performance of Novozyme® 435 for FAME production from waste cooking oil (WCO) under different oil acid values and enzyme-to-oil ratios; (ii) test different regeneration methods and assess the regenerated enzyme’s performance; and (iii) determine FAME yield in continuous operation regime. Oil acid values up to 104 mg KOH.g−1 and enzyme-to-WCO ratios of up to 20:80 (% wt.) were studied, with maximum yield recorded for increasing acid values and enzyme-to-WCO ratio. FAME production from WCO yield ranging 50%–80% was recorded for 5 consecutive production cycles (8h each, in batch regime) with no regeneration of the enzyme. Among the enzyme regeneration methods tested, the highest FAME yield was recorded using t-butanol washing followed by enzyme incubation in the WCO before reusing it. Operation in continuous regime, including enzyme regeneration, produced the highest FAME yield (maximum of 86 %). Thus, effectiveness of the regenerating process and efficiency of continuous production of FAME from WCO (up to 576h) were observed.

Firefighters can suffer serious health problems and experience cardiac disorders derived from high pollutants inhalation. During experimental field burns, environmental and heart rate data from firefighters were collected and it was possible to observe that changes in heart rate were related with variations in pollutants inhalation. Therefore, detecting changes in heart rate may provide a good indicator to identify hazardous situations for firefighters. An automated method, based on the detection of changes in the heart rate, is proposed to prevent and to avoid serious undesirable side-effects in the health of firefighters due to pollutants inhalation. Within the experiments performed, a precision and a recall of 91.5 and 78.2%, respectively, were obtained. Furthermore, this approach can be part of a real-time decision support system for routine use in firefighting practice. Our results show the potential to provide effective support in real operational scenarios and that further research on the impact of environmental conditions in the well-being of firefighters is of utmost importance.

Several harbors, like the Port of Leixões (Porto, Portugal), are located near urban and industrial areas, places where residential urban areas, highways and the refinery industry coexist. The need for assessing the contribution of the port to the air quality in its vicinity around the port is the motivation for the present study. This contribution was investigated using a numerical modelling approach based on the web-based research screening tool C-PORT. The impact of the meteorological conditions (namely atmospheric stability and wind direction) was first evaluated, and the most critical conditions for pollutants dispersion were identified. The dominant wind direction, from WSW, was responsible for the transport of pollutants over the surrounding urban area, which was potentiated by the diurnal sea breeze circulation. Multiple scenario runs were then performed to quantify the contribution of each emission sector/activity (namely maritime emissions; port activities; road traffic and refinery) to the ambient air quality. The multiple scenario runs indicated that land-based emission sources at the Port (including trucks, railways, cargo handling equipment and bulk material stored) were the major contributors (approximately 80%) for the levels of surface PM10 concentrations over the study area. Whereas, the main drivers of NOX concentrations were docked ships, responsible for 55-73% of the total NOX concentrations.

This work focus on the assessment of green infrastructures benefits on air quality in Porto urban area, applying the CFD model VADIS to a particular area within the city. Three scenarios have been considered: (i) the baseline refers to the current morphological characteristics of the area; (ii) a green scenario comprises the replacement of built-up areas by green areas; and (iii) a green scenario corresponding to the implementation of green roofs. The results of baseline simulations shows a good agreement with local measurements with a NMSE of 0.4, 0.6 and 2.1 for CO, NO $$_2$$ and PM10 concentrations, respectively. The benefits of green infrastructures on air quality are assessed for future medium-term climate scenarios (2041–2070), applying a cascade of numerical models, from global to urban scale, the WRF-VADIS modelling system. Future climate data point out a decrease in the number of days with moderate to strong wind speed, and an increase in the number of days recording low wind speed conditions. The assessment of green infrastructures effects on air quality under future climate focus on low wind speed conditions. The results clearly show the disturbances exerted by green infrastructures, which are positively or negatively affecting mainly the adapted areas and their close surroundings.