Search Results (165)

Despite accounting for less than 0.03% of the world’s greenhouse gas emissions, the Pacific Small Island Developing States (PSIDS) face existential threats to their environment, livelihoods, and regional stability due to their heavy dependence on imported fossil fuels and disproportionate climate vulnerability. To address this “Justice Paradox,” this study utilises a Nexus Mapping framework to qualitatively synthesise the non-linear causal pathways between climate stressors and energy system vulnerabilities. Through an integrative thematic synthesis of literature and regional policy documents, the research identifies systemic bottlenecks, including the “fiscal trap” of post-disaster reconstruction, the “demand-utility paradox” of rising temperatures, and the logistical premiums of archipelagic energy distribution. The analysis suggests that energy decarbonisation represents a strategic opportunity to strengthen climate security across four dimensions: human, national, international, and ecological. To facilitate a secure transition, the study proposes a comprehensive “policy mix” of regulatory standards (sticks), economic de-risking through mechanisms such as Sovereign Green Bonds (carrots), and the institutionalisation of local technical sovereignty (sermons). This research offers an interpretive analytical framework for Pacific policymakers, arguing that decentralised, modular renewables may serve as a strategic shield against climatic instability and support the preservation of regional statehood. Full article

Methane (CH₄) is the second most important greenhouse gas after carbon dioxide (CO₂), and its atmospheric concentration is on the rise. Soil CH₄ consumption (=absorption) capacity is declining due to reduced forests and green spaces, as well as other environmental factors and anaerobic stresses. Environmental and stand structure parameters were cross-referenced with publicly available international ecosystem databases, such as FLUXNET, ICOS, NEON, AmeriFlux, the TRY plant trait database and the Oak Ridge FACE site. Searches were conducted using keywords such as region, water level, and stand density. The data indicate that under high-CO₂ conditions, the increase of forest canopy density leads to increased litter accumulation on the forest floor and reduced sunlight penetration, creating anaerobic conditions. This can cause forests to shift from CH₄ consumption to CH₄ release. Based on these findings, we discussed methods to maintain and enhance the CH₄-absorbing capacity of forest soils. This can be achieved through management practices that improve environmental conditions and increase soil fauna’s activity, such as those associated with thinning operations in overmature forest stands across various regions. This ecological manipulation through thinning practices promotes ground-level temperature increases and the activities of soil fauna, as well as maintaining aerobic conditions near the soil surface. Full article

As a carbon-free fuel, ammonia can substantially reduce the carbon footprint of internal combustion engines. However, its slow flame propagation speed and high ignition temperature present combustion challenges. A dual-fuel engine combining ammonia with diesel can effectively address these issues and enhance combustion performance. This study investigates the effects of diesel split ratio (DSR), start of diesel pre-injection (SODI-pre), and start of diesel main-injection (SODI-main). The results indicate that, compared to single diesel injection, segmented diesel injection significantly improves mixture distribution and reactivity, leading to enhanced flame propagation. With a pre-injection ratio of 10% and SODI-pre advanced to −62 °CA, the indicated thermal efficiency increases from 45.35% to 47.61%. Meanwhile, NH₃ emissions decrease from 1707 ppm to 689 ppm, and greenhouse gas N₂O concentration drops from 370 ppm to 251 ppm. Nevertheless, elevated NO_x emissions remain a significant challenge. Full article

In the 21st century, the desire for improved fuel efficiency of engines, lower fuel prices, and the need to reduce greenhouse gas emissions such as ${\mathrm{C}\mathrm{O}}_2$ and ${\mathrm{N}\mathrm{O}}_{\mathrm{x}}$ are leading the aviation industry to seek hybrid-electric jet engines for commercial aircraft. These aircraft will have greater maintenance challenges due to additional components requiring more reliable materials for the engine’s parts, such as turbine blades. Turbine blades must be composed of materials that have enhanced fatigue performance. Resistance to dynamic loads and high strength will be needed to ensure modern gas turbine blades are as reliable as possible. This review paper examines hybrid-electric engine turbine blades and subsequently introduces additive manufacturing (AM) and multi-principal element alloys (MPEAs) with a focus on laser powder bed fusion (LPBF), high-entropy alloys (HEAs), and medium-entropy alloys (MEAs). The tensile properties of LPBF HEAs range from 5 to 47% elongation and a UTS of 572–1640 MPa, while LPBF MEAs range from 8 to 73.9% and a UTS of 573–1382 MPa. This study focused on dynamic and fatigue properties while acknowledging gaps in high-temperature testing. The combination of mechanical properties with the ability to control internal geometry makes these AM alloys an attractive option for the next generation of gas turbine blades. Full article

Industrial production still relies heavily on thermal processes that predominantly use fossil fuels for energy. This has significant consequences for primary energy use and greenhouse gas emissions. Meanwhile, rapid advances in electrotechnologies—defined as processes that use electrical energy to transform materials through internal heat dissipation (inductive, conductive, or dielectric/microwave) or heat transfer via resistance and infrared systems—are paving the way for a transition to a non-fossil fuel-based energy supply across a wide range of temperatures and power densities. However, replacing fuel with electricity is not simply a case of making a straightforward substitution; the feasibility of this change is determined by process requirements, constraints on installation space and grid connection, the reliability and volatility of the electricity supply, and economics. This paper therefore proposes a simple, decision-oriented methodology to assess the feasibility of defossilisation from energetic and economic perspectives. The methodology centres on a “substitution coefficient” that compares the amount of fossil energy substituted by a given amount of electrical energy and benchmarks this against the primary energy intensity of electricity generation. The methodology is demonstrated using case studies from energy-intensive sectors such as cement production (using resistance and microwave methods), steel strip processing (with inductive boosting combined with resistive holding) and metal melting for cast iron and aluminium. The case studies show under which conditions electrification can be implemented as a drop-in substitute, a hybrid booster or an enabler of new production models. The results indicate where electrotechnologies can deliver primary energy savings and CO₂ reductions today and outline the conditions under which their advantages will increase as power systems become more decarbonised. Full article

To meet the global climate change challenge and the International Maritime Organization’s (IMO) greenhouse gas emission reduction strategy, and promote the shipping industry’s transition to clean energy, this study focuses on the 6S35 2-stroke marine low-speed engine to explore hydrogen fuel combustion and emissions in the cylinder. A detailed chemical reaction kinetics model is constructed on the CONVERGE platform, coupling 42 components and 168 elementary reactions, integrating the SAGE combustion model with the extended Zeldovich NOx mechanism for refined numerical simulation of hydrogen combustion. Model validation shows the cylinder pressure peak simulation error is within 5%. Research results indicate hydrogen fuel has significant premixed combustion characteristics with a violent and concentrated heat release. Under simulation, the cylinder explosion pressure reaches about 28 MPa, and the max combustion temperature nears 3000 K, far exceeding traditional diesel engines. In terms of emissions, hydrogen’s carbon-free characteristic keeps CO₂ and CO emissions at extremely low levels (concentrations of approximately 0.02 and 0.085, respectively); whereas NOx emissions exhibit strong “high temperature dependence” and “expansion cooling effect,” with peak concentrations approaching 0.00042. This numerical model can effectively predict the combustion performance of hydrogen fuel, potentially providing a reference for optimizing fuel injection strategies and combustion chamber design to achieve efficient and clean combustion, and offering a theoretical basis for the development and commercial application of marine hydrogen fuel engines. Full article

We develop a minimal thermodynamic model to predict Titan’s surface temperature based on radiative–convective equilibrium and the principle of maximum entropy production (MEP). The model retains only the essential atmospheric constituents: gaseous methane, which absorbs both longwave and near-infrared radiation, and stratospheric haze, which scatters and absorbs solar flux. Subject to Clausius–Clapeyron scaling of methane vapor pressure together with energy balances at the surface, tropopause, and stratopause, the model links the convective flux to the surface temperature, which exhibits a pronounced maximum due to competing radiative effects of tropospheric methane. As the surface warms, enhanced greenhouse effect would strengthen the convection, whereas the rising anti-greenhouse effect would suppress convection. The resulting convective peak corresponds to MEP, which thus selects a surface temperature slightly above methane’s triple point. To assess its long-term evolution, we consider a 20% dimmer early Sun and a hypothetical 20% enrichment of the oceanic methane. Even in combination, they only cool the surface by ~2 K, in sharp contrast to the ~20 K cooling inferred in studies that prescribe haze abundance. This study suggests a critical role of self-adjusting haze in providing the internal degree of freedom necessary for MEP closure, thereby stabilizing Titan’s temperature. Full article

Traditional greenhouse cooling often relies on single-pass evaporative systems that exhaust valuable moisture and CO₂ into the atmosphere. This research introduces a sustainable alternative by developing a laboratory-scale greenhouse that utilizes a closed-loop ducting system to recycle cool, humidified exhaust air back through the evaporative felt pads and water reservoir. Central to this design is an automated control architecture powered by an Arduino Uno and an SCD-30 NDIR sensor module. This low-cost integration enables real-time monitoring and autonomous regulation of fans and water pumps to maintain internal temperature, relative humidity, and CO₂ concentration within optimal physiological limits. The system’s performance was evaluated against a conventional greenhouse model lacking recirculation and automated controls. Experimental results demonstrated that the modified model (smart) significantly outperformed the standard setup (traditional), achieving an improved temperature reduction by a higher rate of 1.45 °C, compared to only 1.03 °C in the traditional model, and a significant increase in relative humidity, reaching about 9.30%, compared to only 3.36% in the traditional model. While the traditional model experienced CO₂ dissipation, the experimental system successfully retained and regulated Carbon Dioxide levels, increasing concentrations from 497 to 552 ppm. These findings suggest that integrating smart automation with air-recirculation infrastructure represents a potential trail for improving resource management in controlled greenhouse environments under arid conditions. Full article

N₂O emissions exacerbate the greenhouse effect, urgently demanding advances in abatement technologies. Catalytic decomposition of N₂O over cobalt-based oxides with alkali metal promoters remains challenging because these catalysts are used in pelletized form, limiting their activity to a narrow outer-shell region due to internal diffusion limitations. However, research efforts continue to focus on enhancing Co–alkali metal contact on unsupported powder samples under inert conditions, even though, under industrial conditions, catalysts are exposed to inhibitory components of waste gases and N₂O, and the powder form is unsuitable for practical application. This study aims at testing N₂O decomposition over catalysts with a Co₃O₄-Cs active phase supported on a ceramic foam. For this purpose, we characterized these catalysts by H₂ temperature-programmed reduction, H₂O and NO temperature-programmed desorption, atomic absorption spectroscopy, and X-ray diffraction and assessed their catalytic performance under an inert-gas atmosphere and with O₂, water vapor, and NO to simulate industrial conditions. Using a pseudo-homogeneous, one-dimensional model of an ideal plug flow reactor in an isothermal regime, the simulation calculations for a full-scale catalytic reactor for N₂O abatement in waste gas from HNO₃ production were performed. The Cs₂CO₃ precursor significantly enhanced catalyst reducibility and electron transferability, increasing N₂O decomposition efficiency in inert gas, but its high hygroscopicity decreased resistance to water vapor and NO, overriding its advantages under industrial conditions. Conversely, glycerol-assisted impregnation enhanced catalyst performance regardless of Cs precursor. These foam-supported catalysts offered several other advantages, including lower pressure drop and lower active phase loading with matching catalytic activity. Based on our findings, depositing Cs₂CO₃ on ceramic foam through glycerol-assisted impregnation may facilitate catalytic N₂O decomposition at the industrial level and, therefore, promote environmental sustainability by reducing N₂O emissions. Full article

The optical properties of greenhouse cover materials play a critical role in controlling the internal light environment, directly affecting photosynthetic performance and crop productivity. This study evaluates the impact of a high photosynthetically active radiation (PAR) transmittance and high-light-diffusivity polyethylene film on the microclimate, photosynthetic activity, yield, and disease incidence of cucumber (Cucumis sativus L.) crops grown in a Mediterranean passive solar greenhouse. Trials were conducted over two consecutive autumn–winter seasons using a multi-span greenhouse divided into two sectors: one covered with an experimental high-transmittance film and the other with a standard commercial plastic. The experimental cover increased PAR transmission by 8.7% and 11.6% at canopy level in the first and second seasons, respectively, leading to improvements in leaf-level net photosynthesis of 9.3% and 17.9%. These effects contributed to yield increases of 5.0% and 17.3% in the respective seasons. The internal air temperature rose by up to 1.3 °C without exceeding critical thresholds, and no significant differences were observed in plant morphology or fruit quality between treatments. Additionally, the experimental film reduced the incidence of major fungal diseases, particularly under higher disease pressure conditions. The use of high-PAR-transmittance films enhances radiation use efficiency and crop performance in resource-limited environments without increasing energy inputs. This approach offers a sustainable, low-cost strategy to improve yield and disease resilience in protected cropping systems under passive climate control. Full article

Soil mulching materials play an important role in regulating the greenhouse crop microclimate, as they influence light distribution, plant physiological activity, and crop yield. The aim of this study was to evaluate the effects of two plastic mulches (black polypropylene and white polyethylene mulch) on the microclimate, photosynthetic activity, crop development, yield, and fruit quality of sweet pepper (Capsicum annuum L.) grown under greenhouse conditions. The trial was developed during a spring–summer growing cycle in a single multispan greenhouse divided into two compartments (sectors) separated by a vertical polyethylene sheet. In the eastern sector of the greenhouse (control treatment), a black polypropylene agrotextile mulch with a thickness of 2500 μm was installed, while in the western sector, a white polyethylene plastic mulch (black on the inner side) with a thickness of 30 μm was used. The use of white polyethylene mulch resulted in slightly higher mean and maximum PAR inside the greenhouse by up to 3.7% compared with black polypropylene mulch, leading to slightly higher leaf-level PAR and net photosynthetic rate. Although no significant differences were observed in plant morphology or fruit quality parameters, marketable yield increased by 66% and total yield by 40% under white polyethylene mulch. Slight increases in internal air temperature were recorded without exceeding critical thresholds, while relative humidity remained largely unaffected. The use of reflective mulches may represent a promising low-cost and sustainable strategy to improve pepper yield and radiation-use efficiency in passively ventilated greenhouse systems under Mediterranean climatic conditions. Full article

Between 2022 and 2024, a severe branch dieback disease was observed affecting over 6% of sweet cherry trees of the ‘Tieton’ cultivar in commercial greenhouses in southern Liaoning Province, China. Symptoms primarily occurred at the top of young branches. At the early stage of disease onset, the lesions appeared as dark brown, irregularly shaped areas with a moist surface; as the disease progressed, these lesions turned dry and rotten, leading to tree decline symptoms in sweet cherry trees. Disease diagnosis was carried out in sweet cherry greenhouses across Liaoning Province, where 24 diseased samples were collected and 14 fungal isolates were obtained therefrom. Based on morphological traits, cultural characteristics, and multi-locus phylogenetic analyses of the internal transcribed spacer (ITS) region, beta-tubulin (TUB2) gene, and translation elongation factor 1-α (TEF1) gene, these isolates were identified as Botryosphaeria dothidea. Two representative isolates, namely zdcy-1 and zdcy-2, were selected for pathogenicity assays. Both mycelial plug and spore suspension inoculation methods confirmed the pathogenicity of the pathogen. The biological characteristic assays revealed that the optimal temperature range for the pathogen’s mycelial growth on PDA medium was 25–28 °C, and the optimal pH range was 6.0–8.0. This study improves the understanding of branch dieback disease in sweet cherry orchards in China, enriches the knowledge regarding the geographical distribution, host range, and infection sites of the pathogen, and provides novel insights for the management of sweet cherry diseases. Full article

Piggery farming is the largest source of livestock manure in South Korea, yet greenhouse gas (GHG) data from piggery wastewater treatment systems remain limited. This study quantified methane (CH₄) and nitrous oxide (N₂O) fluxes from a full-scale treatment facility to develop stage-, seasonal-, and diurnal-specific emission factors. Continuous laser-based monitoring using a PVC air-pool chamber was applied across raw wastewater storage, an anoxic nitrogen-conversion reactor, and strongly aerated nitrification units. Mean CH₄ fluxes ranged from 1.1 to 15.6 mg s⁻¹ m⁻² peaking in summer, while N₂O fluxes ranged from 0.01 to 17,971 mg s⁻¹ m⁻², with maxima in fall. Emissions were dominated by two functional zones: aerated basins where vigorous mixing enhanced CH₄ stripping, and an upstream anoxic reactor where oxygen instability and nitrite accumulation produced extreme N₂O peaks. Derived emission factors were 0.11 kg CH₄ head⁻¹ yr⁻¹ and 45.2 kg N₂O head⁻¹ yr⁻¹, equivalent to 3.1 and 12,300 kg CO₂-eq head⁻¹ yr⁻¹. CH₄ variability was controlled mainly by treatment stage and temperature, whereas N₂O was governed by internal redox conditions. These results refine emission factors for inventories and underscore the need for improved aeration stability and denitrification control to reduce GHG emissions from piggery wastewater systems. Full article

Integrating electrochemical fuel cells and internal combustion engines can enhance the total efficiency and sustainability of power systems. This study presents a promising solution by integrating a Proton Exchange Membrane Fuel Cell (PEMFC) with a mini gas turbine, forming a hybrid system called the “Oya System.” This approach aims to mitigate the efficiency losses of gas turbines during high ambient temperatures. The hybrid model was designed using Aspen Plus for modelling and the EES simulation program for solving mathematical equations. The primary objective of this research is to enhance the efficiency of gas turbine systems, particularly under elevated ambient temperatures. The results demonstrate a notable increase in efficiency, rising from 37.97% to 43.06% at 10 °C (winter) and from 31.98% to 40.33% at 40 °C (summer). This improvement, ranging from 5.09% in winter to 8.35% in summer, represents a significant achievement aligned with the goals of the Oya System. Furthermore, integrating PEMFC contributes to environmental sustainability by utilising hydrogen, a clean energy source, and reducing greenhouse gas emissions. The system also enhances efficiency through waste heat recovery, further optimising performance and reducing energy losses. This research highlights the critical role of interface engineering in the hybrid system, particularly the interaction between the PEMFC and the gas turbine. Integrating these two systems involves complex interfaces that facilitate the transfer of electrochemistry, energy, and materials, optimising the overall performance. This aligns with the conference session’s focus on green technologies and resource efficiency. The Oya System exemplifies how innovative hybrid systems can enhance performance while promoting environmentally friendly processes. Full article

Socio-ecological systems (SESs) exhibit nonlinear feedback across environmental, social, and economic processes, requiring integrative analytical tools capable of representing such coupled dynamics. This study presents a quantitative framework that integrates a compartmental model of a global human–ecosystem with two complementary optimization approaches (Fisher Information (FI) and Multi-Objective Optimization (MOO)) to evaluate policy strategies for sustainability. The model represents biophysical and socio-economic interactions across 15 compartments, incorporating feedback loops between greenhouse gas (GHG) accumulation, temperature anomalies, and trophic–economic dynamics. Six policy-relevant decision variables were selected (wild plant mortality, sectoral prices (agriculture, livestock, and industry), base wages, and resource productivity) and optimized under temporal (25-year) and magnitude (±10%) constraints to ensure policy realism. FI-based optimization enhances system stability, whereas the MOO framework balances environmental, social, and economic objectives using the Ideal Point Method. Both approaches prevent the systemic collapse observed in the baseline scenario. The FI and MOO strategies reduce terminal global temperature by 11.4% and 15.0%, respectively, relative to the baseline (35 °C → 31.0 °C under FI; 35 °C → 29.7 °C under MOO). Resource-use efficiency, measured through the resource requirement coefficient (λ), improves by 8–10% under MOO (0.6767 → 0.6090) and by 6–7% under FI (0.6668 → 0.6262). These outcomes offer actionable guidance for long-term climate policy at national and international scales. The MOO framework provided the most balanced outcomes, enhancing environmental and social performance while maintaining economic viability. Overall, the integration of optimization and information-theoretic approaches within SES models can support evidence-based public policy design, offering actionable pathways toward resilient, efficient, and equitable sustainability transitions. Full article