Abstract

Cold storage systems represent a substantial electricity burden for food-processing micro, small, and medium-sized enterprises. This study developed a smart monitoring and multicriteria operational evaluation system to support energy-aware cold storage management. The system integrated room temperature, operating setpoint, door status, and electrical power data, and was evaluated on a 15 m³ cold storage unit operated predominantly at a −20 °C setpoint. Electrical parameters were measured using a power meter, while operational performance was assessed using weighted criteria comprising energy performance, temperature stability, and door-opening disturbance. The unit exhibited an average active power of 2.14 kW and an average daily energy consumption of 50.92 kWh/day, corresponding to an estimated electricity cost of 73,568 IDR/day or 2.21 million IDR/month. The multicriteria operational score ranged from 0.290 to 0.720, indicating that all evaluated operating days were suboptimal, primarily because of limitations in temperature stability. These findings show that cold storage performance cannot be assessed from energy consumption alone and that integrated monitoring with multicriteria evaluation can provide practical decision-support information for improving energy management in micro, small, and medium-sized enterprises cold storage operations.

Abstract

A laboratory–scale mechanical draft cooling tower equipped with eight sections of perforated inclined plates was designed to determine the effect of operating conditions on the volumetric mass transfer coefficient between water and air. A three–factor, three–level design of experiments was implemented, considering liquid mass flow rate (120, 240, and 360 kg/h), gas mass flow rate (36, 57, and 75 kg/h), and top water temperature (50, 60, and 70 °C). A total of 54 runs were performed, and the global volumetric mass transfer coefficient was calculated by combining energy and mass balances with the Mickley method. The experimental data were fitted to a power–law correlation using multivariable regression. The analysis of variance showed that top water temperature is the dominant factor, followed by liquid mass flow rate, whereas the influence of gas mass flow rate is comparatively small in the studied range. The selected correlation, based on the nominal gas flow rate, achieved a coefficient of determination of 0.869 and a root mean square error of 5.93×10³ kg/m³h. The volumetric mass transfer coefficient values were found in the range from 4.6×10³ to 6.2×10⁴ kg/m³h. Vertical temperature profiles of water and air along the column revealed that, for high liquid flow rates, most of the cooling occurs in the lower stages, suggesting that the upper sections are underutilized.

Abstract

The paper investigates the design and performance of humidifiers used in low-grade heat-driven desalination systems. It reviews the advantages and limitations of common humidifier types and presents an experimental study of a film-type humidifier configured as a vertical acrylic tube. Experiments examined hydrodynamics and heat and mass transfer over air mass flow rates of 7.4–35 kg/h, water mass flow rates of 10–80 kg/h, inlet water temperatures of 28–59 °C, air pressure drops of 19–324 Pa, water pressure losses of 22.3 kPa, and heater power inputs of 90–554 W. Optimal operating conditions were identified to maximize system performance and energy efficiency. A thermodynamic model based on heat and mass transfer equations was developed and validated. Compared with other humidifier designs, the film-type humidifier achieved the highest evaporation rate at equivalent operating conditions while maintaining minimal aerodynamic and hydraulic resistance, thereby reducing electricity consumption for air and water circulation without performance losses.

Abstract

This study introduces a computational tool developed to identify the most sustainable alternative for integrating a hybrid renewable energy system. The approach brings together a fuzzy optimisation model, focused on minimising both the Net Present Value and carbon dioxide emissions, with the Fuzzy Analytical Hierarchy Process, incorporating economic, technical, environmental, and social criteria. To enhance usability, the tool includes an Excel-based module that allows users to adjust quantitative parameters, while qualitative aspects can be modified through editable comparison matrices in the main graphical interface. This flexibility makes it adaptable to a wide range of geographical and contextual scenarios. The proposed framework was applied in a pilot-scale case study in the municipality of Tona, Colombia. The selected energy mix consists of 57.56% photovoltaic solar energy, 35.42% biomass-based generation, and 7.02% diesel generation, achieving a Net Present Value of USD 1,765.68 and total emissions of 1,216.08 kg of carbon dioxide.

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Abstract

Meeting climate targets requires sustainable energy systems and proactive municipal heat planning. This paper aims to investigate how different spatial aggregation levels impact the accuracy of heat demand prediction. For this purpose, the energy demand calculated by a state-provided and publicly available urban building energy model is compared with a comprehensive high-resolution consumption dataset from the city of Krefeld in Germany. The latter includes detailed consumption data for district heating, natural gas, heat pumps, and night storage heaters. Box plot diagrams and statistical performance indicators are applied to evaluate the precision of various spatial aggregation levels. The results demonstrate that aggregations at the level of postcode areas, statistical districts and cadastral sectors can provide a reliable foundation for planning purposes. Aggregation at the level of building blocks and heat lines provides an improvement compared to individual parcels, but it should be applied in planning practice with due consideration of the remaining uncertainty. This paper also examines the model deviation between simulated and measured data based on building age class, building type and heat carrier. Furthermore, this paper identifies an underestimation by the state-provided Urban Building Energy Model of around 25%.

Abstract

Nature-Based Solutions are contemporary approaches to restoring spatially defined urban and landscape areas. An important requirement is that restoration is carried out using green (vegetation) and/or blue (water) infrastructure, including green-blue combinations and hybrid solutions with a modest share of grey infrastructure, for example, concrete and metals. Defining the societal challenges that the restoration should address and respect is essential. The European Commission defines Nature-Based Solutions as nature-inspired, cost-effective solutions that support both biodiversity and human wellbeing. Within the European Commission project "Ecosystem-based governance with Danube lighthouse Living Lab for sustainable Innovation processes", the task was set to develop a methodology for assessing Nature-Based Solutions relevant to the European Union Mission Ocean and Waters in the Danube River Basin. This article reviews a comprehensive body of publications on Nature-Based Solutions and synthesises them into a structured framework for restoration projects. The synthesis can be useful for future practitioners by reducing working time and costs. In addition to the assessment procedure, the framework is extended with a toolbox for practitioners and implementers. It is structured using a flowchart that includes descriptions of activities, the related documents, and relevant decision points. The framework should be treated as a baseline that can be readily upgraded and adapted to specific restoration cases. It incorporates participatory planning and governance, involving stakeholders and participatory democracy, as well as citizen engagement, especially in the monitoring and evaluation phase, which is grounded in deliberative democracy.

Abstract

Industrial incineration is widely used to treat potentially toxic waste, but the resulting bottom ash poses environmental and economic challenges. This study was motivated by the need to assess the potential reuse of bottom ash in sustainable applications. The working hypothesis was that quenching could influence ash homogeneity, trace metal distribution, and valorisation potential. Bottom ash samples were analysed for chemical composition, trace metal content, organic carbon, particle size, density, and mineralogical structure. Results show that the ash is mainly composed of iron, aluminium, silicon, and calcium oxides, with moderate organic content. Quenched bottom ash exhibited a more uniform particle size distribution, reduced variability in several trace metal concentrations, and higher particle density compared with dry bottom ash. Statistical analysis showed reduced variability of chromium, nickel, cadmium, lead, and zinc after quenching. However, the results should be interpreted with caution due to the limited sample size and ash heterogeneity. Mineralogical analysis revealed ceramic fragments, glass phases, ferrous materials, and residual carbonaceous fractions. Quenching improved material homogeneity and indicates potential for reuse in construction applications. However, no leaching tests were performed; thus, environmental stability and mobility remain unconfirmed.

Abstract

Climate Change is intensifying urban risks and widening inequalities, requiring Climate Adaptation strategies capable of protecting populations and ecosystems. This study was motivated by the need to understand how Green Infrastructure, as Nature-based Solutions, can strengthen urban adaptation and resilience and support the Sustainable Development Goals. It builds on the hypothesis that the effectiveness of these solutions depends on regulatory institutionalisation, cross-sectoral integration, and equity safeguards to avoid new socio-spatial injustices. The study also reviewed recent international literature and conducted a documentary analysis of the Campinas Local Climate Action Plan to compare typologies, instruments, and enabling conditions. The results highlight climate and quality-of-life benefits, but also recurring barriers related to monitoring, indicators, maintenance, legal frameworks, and social participation, alongside risks of green gentrification. It is concluded that moving from rhetoric to implementation requires inclusive governance, stable financing, and operational mechanisms that ensure continuity and justice in urban adaptation.

Abstract

This study evaluated two low-cost technologies for groundwater extraction in the high Andean community of Chachapoyas, Peru: the rope pump and the manual volumetric pump. The rope pump, constructed from local materials and operated by pedalling, showed a progressive increase in flow rate from 48.79 L/min (1 m) to 69.56 L/min (5 m), associated with greater immersion and stability of the water column. In contrast, the manual volumetric pump exhibited a decrease in flow rate as the discharge height increased, from 21.97 L/min (2 m) to 11.68 L/min (10 m), reflecting the hydraulic limitations inherent in positive displacement systems. Both technologies are viable for domestic and agricultural water supply in rural communities with limited energy resources. The results highlight the need to adapt their design and maintenance to local hydrogeological conditions to ensure their operational sustainability.

Abstract

This study presents an integrated framework combining thermal pinch analysis and life cycle assessment to evaluate energy-intensive industrial processes, addressing the need to capture both operational efficiency and environmental impacts. The goal is to determine whether energy savings from process integration justify associated environmental burdens. The method links utility targets and heat exchanger network designs to life-cycle inventory data, while explicitly including heat exchanger manufacturing impacts. Three industrial cases - ammonia, bioethanol, and hydrogen production from biomass-based resources - were analysed. Results show energy use reductions of 62.27–76.05% and cost savings of 45.81–65.38%. Environmental impacts, including global warming and resource depletion, decreased significantly, although minor trade-offs appeared in ozone depletion and mineral resource use due to added equipment. The framework reveals hidden burden shifting and supports transparent decision-making for industrial decarbonization strategies.

Abstract

Solid biomass is expected to remain a relevant option for heat decarbonisation in Serbia. Yet, its environmental performance depends heavily on supply chain design, including non-road machinery, logistics, and the electricity mix used in processing. This study provides a comparative life cycle assessment of two technically feasible supply chains operating under Serbian conditions: (i) beech (Fagus sylvatica L) wood chips produced in high natural forests using a tree-length system (felling and processing, extraction, chipping, and long-distance trucking), and (ii) Miscanthus giganteus briquettes produced from a perennial energy crop (harvesting, baling and loading, short-distance tractor hauling, electricity-driven briquetting, and trucking to market). The primary functional unit is one tonne of processed biomass delivered to the market or end user, consistent with operation-level foreground data (productivity and fuel use per tonne). In addition, results are expressed per unit of useful heat delivered by combining the as-delivered lower heating value with an assumed end-use efficiency, to support screening across household, district-heating, and industrial heat applications. Midpoint impacts are quantified for climate change, ozone depletion, terrestrial acidification, freshwater eutrophication, photochemical ozone formation, and particulate matter formation. Per tonne delivered biomass, climate change impacts are comparable: 35.0 kg CO₂ equivalent for beech wood chips and 33.5 kg CO₂ equivalent for Miscanthus briquettes. On an energy-service basis, using the derived as-delivered lower heating values and a representative district-heating efficiency η = 0.88, climate change impacts are 3.43 kg CO₂ equivalent per GJ useful heat for beech wood chips and 2.75 kg CO₂ equivalent per GJ useful heat for Miscanthus briquettes, indicating a clearer separation than on a mass basis due to differences in delivered energy per tonne. Non-climate categories show pronounced trade-offs: beech wood chips exhibit higher ozone depletion and photochemical ozone formation, whereas Miscanthus briquettes exhibit higher terrestrial acidification and particulate matter formation under the current Serbian electricity mix due to electricity demand during briquetting. The results are intended for screening-level hotspot identification and prioritisation of improvement levers, rather than for product declarations or comparative marketing claims.

Abstract

Water management is an increasingly important sustainability challenge in the water intensive pulp and paper industry. This study evaluates water management maturity and water use efficiency at three pulp and paper mills operated by the same company in Sweden, France, and Brazil. The analysis combines long term water use data with a structured self-assessment framework based on Best Available Techniques, water footprint principles, and water related risk criteria, complemented by semi structured interviews with site level personnel. The results show that mills exposed to higher water scarcity risks place greater strategic emphasis on water issues and exhibit more advanced management practices. While all mills have achieved improvements through optimisation of existing internal water flows, notable differences remain in governance structures, indicator utilisation, and risk awareness. Substantial performance gains can be achieved without major investments. Key recommendations include adopting a system wide perspective, clarifying water governance responsibilities, and strengthening monitoring and performance evaluation.

Abstract

Remote mangrove ecotourism sites, constrained by environmental sensitivity and limited grid access, rely on costly, polluting diesel generators. This study designs and validates hybrid renewable energy systems for sustainable tourism in the Sundarbans (Bangladesh), Can Gio (Vietnam), and Guaratiba (Brazil). Using HOMER Pro, system sizing and long-term costs are optimised on the basis of local solar, wind and biomass resources and multi-sector electricity demand, while DIgSILENT PowerFactory is used to verify steady-state and dynamic performance through load-flow and fault analyses. The optimised hybrid systems achieve 80–85% renewable penetration, with the Sundarbans leading due to strong wind and biomass resources, and reduce total energy costs by 22–35% and greenhouse gas emissions by more than 70% compared to diesel-only supply. Across the three sites, the levelized cost of energy falls in the range of approximately 0.11–0.21 USD/kWh, versus more than 0.30 USD/kWh for existing diesel-based generation, while the contribution of diesel generation is greatly reduced, consistent with the large decrease in associated emissions. Voltage deviations remain within ±5% of nominal levels, line loadings stay below thermal limits and fault recovery under 2 seconds, indicating that the proposed configurations can provide reliable and resilient power under disturbed operating conditions. Overall, the integrated HOMER–DIgSILENT framework offers a scalable model for planning low-carbon electrification of ecologically sensitive mangrove regions, supporting progress towards Sustainable Development Goals 7 (affordable and clean energy), 8 (decent work and economic growth), 9 (industry, innovation and infrastructure), 13 (climate action) and 15 (life on land), while enhancing local energy security and sustainability.

Abstract

This study investigates meteorological drought patterns in the Balkhab Sub River Basin (BSRB) from Oct-1981 to Sep-2024 using satellite-based Climate Hazards Group InfraRed Precipitation with Stations (CHIRPS) precipitation data and four drought indices: Normal-SPI, Log-SPI, SPI-12, and PNPI. Data from eight selected points across the basin were analyzed to evaluate drought severity, identify critical drought years, and assess spatial-temporal drought distribution. The CHIRPS data showed strong correlation with ground observations (R² ≈ 0.91), confirming its reliability. The SPI-12 index effectively captured long-term droughts, while PNPI was sensitive to short-term variability. All indices identified 2001 as an extreme drought year across all points. Other significant drought years included 1985, 1986, 2022, and 2023. Spatial analysis indicated higher drought frequency in points R1, R2, R3, and R8. The study concludes that CHIRPS data, combined with multiple indices, offer a robust approach for drought monitoring in data-scarce regions, supporting future water resource planning and climate resilience strategies in BSRB.

Abstract

This work presents an analysis of the contributions of plant interception and evapotranspiration to the water balance of a bromeliad green roof, based on experimental tests conducted in a prototype. The objective is to calculate the volume of water intercepted by bromeliads and the volume of water that undergoes evapotranspiration, and to compare these volumes with the volume precipitated over the green roof and the volume retained, to improve understanding of the mechanism of interaction among the parts. The main purpose is to improve the efficiency of compensatory techniques in urban drainage, thereby minimising urban flooding across all major cities. A literature review was conducted on the hydrological cycle and its stages, along with a description of the history and advantages of green roofs, to improve understanding of the system’s operation. This work contributes to improving the efficiency of green roofs for rainwater retention.

Abstract

Mineral carbonation of steel slags has shown potential as a viable option for carbon capture, utilisation, and storage. This process not only valorises both steel slags and the carbon emissions generated during steel production, but also offers an interesting agricultural application. Carbonated steel slags can serve as substitutes for liming agents or basalt rock powder, and, even when used in agriculture, they continue to capture carbon dioxide throughout their use phase. To ensure that the carbon dioxide captured during the mineral carbonation process exceeds the emissions generated by the process, a life-cycle assessment is necessary. This life-cycle assessment must incorporate the temporal aspects to monitor emissions and sequestration over time, which is critical for evaluating carbon capture, utilisation, and storage technologies. Additionally, including the temporal aspect helps determine whether mineral carbonation is essential, allowing comparison of the carbon dioxide captured during both the production (carbonation) and use phases of both carbonated and non-carbonated slags in agriculture. To address this gap, this study proposes an integrated environmental life-cycle assessment combined with a dynamic life-cycle assessment to track emissions and sequestration over time. This approach enables the visualisation of time-dependent radiative forcing and the cumulative carbon dioxide capture throughout both the production and use phases of carbonated slags. The study utilises empirical data collected from the AgriCarb project, funded by the Research Foundation Flanders. This project includes steel slag carbonation and emissions measurements over 435 days to demonstrate the proposed integrated conventional and dynamic life-cycle assessment framework. At the time of writing this abstract, no known studies have applied dynamic life cycle assessment to a carbon capture, utilisation, and storage case study, making this research novel and the first to demonstrate such a framework in this context. Preliminary results from the assessment show that carbonated slags sequestered more carbon dioxide over the 435 days, combining sequestration from both the carbonation process and the agricultural use phase, compared to non-carbonated slags. The findings quantitatively demonstrate the environmental benefits of mineral carbonation. This integrated framework offers a practical, quantitative approach to evaluating mineral carbonation of steel slags as a carbon capture, utilisation, and storage technology and provides a valuable tool for future assessments of other technologies in these fields.

Abstract

The rapid growth of aluminium production in Saudi Arabia has led to proportionally greater amounts of industrial waste, presenting both environmental risks and opportunities for resource recovery. The hydrolysis of waste aluminium slag through seawater to create green hydrogen along with aluminium hydroxide is presented in this work as a potential to improve waste management through the conversion of aluminium waste into marketable products, thereby reducing greenhouse gas emissions and creating financial opportunities that promote sustainable resource management and green energy solutions, supporting the kingdom’s Vision 2030 energy transition plans. This case study utilises the XGBoost machine learning algorithm to forecast aluminium production growth in Saudi Arabia and to estimate future availability of aluminium slag, as well as hydrogen and aluminium hydroxide production. Economic growth and industrial demand served as the basis for these estimates. The model achieved a Mean Absolute Percentage Error of 6.9%, and analysis shows that aluminium production is projected to increase from 784.88 kilotonnes in 2025 to 1,058.42 kilotonnes in 2041, with slag generation rising from 156.98 to 211.68 kilotonnes and enabling up to 6.83 million kilograms of green hydrogen and 176.2 kilotonnes of aluminium hydroxide annually by 2041. The economic analysis indicated that the process relies strongly on the dual-value stream generated by hydrogen and aluminium hydroxide, supporting the commercial attractiveness of aluminium slag valorisation. The economic viability, carbon-mitigation benefits, and industrial-growth potential of this approach contribute to sustainable energy research by integrating AI-driven forecasting with circular waste-to-hydrogen valorisation to decarbonise the aluminium sector in the region.

Abstract

This work evaluated the potential reuse of solid effluents from a Moringa oleifera infusion production company as adsorbents for the removal of nickel from aqueous media. To enhance adsorption performance, the material was chemically modified through an alkaline pretreatment, followed by carboxymethylation or acetylation. The obtained products were characterised by Fourier Transform Infrared spectroscopy to confirm the incorporation of functional groups. The adsorption capacity of the materials was determined, revealing that the moderate improvement observed for the carboxymethylated sample does not justify its low synthesis yield and the increased process complexity. Therefore, only the raw material, the alkaline-pretreated sample, and the acetylated adsorbent were selected for detailed evaluation. Kinetic and equilibrium experiments, as well as packed-column tests, demonstrated that moringa residues exhibit promising performance for the removal of nickel ions. Overall, the results highlight moringa-based materials as low-cost, sustainable adsorbents for wastewater treatment.

Abstract

This study presents a technology-agnostic framework for analysing wind–solar hybridisation from a resource-based perspective, focusing on integration-relevant temporal behaviour. Renewable availability is represented using normalised signals, enabling the evaluation of variability and inter-period transition intensity as key indicators of temporal dynamics. The results reveal a non-linear response to the mixing parameter, with variability minimised at balanced wind–solar contributions, while transition intensity reaches its minimum at higher solar shares. This non-coincidence highlights an inherent trade-off between different integration objectives. A demand-aware residual proxy is introduced to assess temporal alignment between renewable availability and electricity demand, indicating improved alignment under hybrid configurations at monthly resolution. The framework operates independently of technology-specific assumptions and dispatch modelling, providing a transparent basis for early-stage planning and hybrid configuration screening. The findings demonstrate how resource complementarity can be systematically linked to integration-relevant behaviour across temporal scales.

Abstract

Silver nanoparticles discharged from wastewater treatment plants pose potential risks to aquatic environments and, in the long term, may cause serious human health issues, hindering quality of life. Limited research has been conducted, making it difficult to ensure efficient removal of silver nanoparticles in wastewater treatment plants. This study evaluates the removal efficiency of silver nanoparticles across three wastewater treatment plant layouts: conventional activated sludge, an anoxic/oxic process configuration, and a 4-stage Bardenpho process system. Silver nanoparticle removal efficiency was 82%, and nitrogen removal efficiency exceeded 95% under steady-state conditions; however, under dynamic conditions, significant efficiency reductions were observed in the Bardenpho and anoxic/oxic configurations. The results also showed variability in organic matter and nitrogen removal due to reduced internal recirculation flowrates. The findings highlight the need to optimise certain configurations to ensure balanced performance across all pollutants.