Search Results (132)

Central Asia faces increasing pressure on transboundary water, energy and food systems, particularly in the Aral Sea Basin, where hydropower, agriculture and downstream water availability are closely linked. This study applies a spatially disaggregated Water–Energy–Food (WEF) Nexus System Dynamics Model under combined climate–socioeconomic scenarios (SSP1-2.6, SSP2-4.5 and SSP5-8.5) to assess hydropower development and policy pathways at basin and sub-basin scales in the Amu Darya and Syr Darya basins during 2015–2050. At basin scale, mean annual water supply remains stable across scenarios, at approximately 42 and 87 million hm³/year, respectively. Under national hydropower plans, installed capacity nearly doubles by 2050, reaching 10.45 and 10.65 GW, respectively. Food supply is more sensitive to climate–socioeconomic pathways than to hydropower expansion, with 2050 values ranging from 1120 to 1370 tonnes in the Syr Darya and 1405 to 1780 tonnes in the Amu Darya. Spatial simulations show that upstream-only development concentrates energy gains, whereas integrated basin-wide planning delivers more balanced WEF outcomes and the highest Aral Sea inflows, reaching 8.41 million hm³/year and 17,319 hm³/year, respectively. Persistent Amu Darya trade-offs underscore the need for transboundary coordination in reservoir operation, irrigation planning and downstream-flow safeguards. Spatial disaggregation reveals trade-offs concealed by basin-scale averages. Full article

Artificial intelligence (AI) data centers are creating large, power-dense loads, often faster than transmission lines, substations, transformers, and grid interconnections can be expanded. This review assesses whether solid oxide fuel cells (SOFCs) can provide dependable on-site power during these grid delivery constraints and remain competitive after grid capacity becomes available. We critically synthesized evidence on AI electricity demand, competing power supply options, SOFC efficiency and durability, commercial deployments, environmental impacts, thermal and electrical integration, and hybrid SOFC–battery–grid systems. We also performed a screening-level levelized cost of electricity sensitivity analysis covering natural gas prices, carbon costs, stack replacement, grid electricity prices, and the avoided cost of delayed grid access. The evidence indicates that commercial SOFC systems can achieve approximately 50–60% net electrical efficiency and scale modularly from 325 kW units to a planned deployment of up to 2.45 GW. A nominal 100 MW installation would require approximately 308 such modules and at least 3600 m² of direct equipment area, excluding auxiliary systems and safety setbacks. However, multi-year durability targets of about 40,000 h, fuel and carbon price exposure, slow transient response, lifecycle methane emissions, and limited opportunities to use high temperature exhaust heat remain important constraints. The economic analysis indicates that avoided grid delay costs can justify SOFCs as bridge assets, whereas long-term retention requires competitiveness without this temporary benefit. SOFCs are therefore most suitable for sites that prioritize rapid access to firm power, modularity, reliability, and low local air pollutant emissions, rather than as a universal alternative to grid expansion. Full article

South Africa possesses substantial bioenergy potential derived from agricultural residues, forestry by-products, municipal organic waste, wastewater sludge, and dedicated energy crops, positioning bioenergy as a potentially important contributor to the country’s low-carbon energy transition. Despite more than two decades of supportive policy, modern bioenergy remains a marginal contributor to the country’s energy system. Although previous studies have examined individual bioenergy technologies, feedstocks, environmental impacts, or policy frameworks, a comprehensive assessment of the alignment between policy ambition, technological readiness, implementation outcomes, and emerging sustainable development opportunities in South Africa remains lacking. This review presents a systematic integrative review of bioenergy development in South Africa, evaluating the alignment between policy ambition, technological readiness, and implementation outcomes. Literature published between 2000 and 2025 was systematically reviewed using Scopus, Web of Science, Google Scholar, and institutional publications. A PRISMA-informed screening process identified 427 records, of which 116 studies met the inclusion criteria for detailed synthesis. Evidence was synthesized across three interconnected dimensions: (i) policy and regulatory frameworks, (ii) feedstock availability and technological readiness, and (iii) deployment outcomes, implementation challenges, and future development opportunities. The findings reveal a persistent implementation gap despite abundant biomass resources and commercially established bioenergy conversion technologies Although global biofuel production exceeded 180 billion liters in 2023, South Africa’s installed bioenergy electricity capacity remains approximately 265 MW, representing less than 0.5% of the country’s approximately 60 GW installed electricity generation capacity. By comparison, installed solar and wind capacities exceed 8 GW and 3 GW, respectively. The review identifies fragmented governance, limited investment incentives, regulatory uncertainty, infrastructure constraints, and inadequate integration of bioenergy into national energy planning as the principal barriers to deployment. The review concludes that South Africa’s principal challenge is not biomass availability or technological capability, but translating policy ambition into coordinated implementation capable of scaling sustainable bioenergy deployment. Full article

A comprehensive beyond density functional theory study of the structural, energetic, and electronic properties of the technologically most relevant SiC polytypes 3C, 2H, 4H, and 6H-SiC, together with the single Shockley-type stacking fault (1SSF or 31SSF) in 4H-SiC, was conducted. Lattice constants computed at the PBEsol and HSE06 level match experimental values within 0.1% accuracy. Total energies evaluated at the random-phase approximation level yield a physically consistent hierarchy of polytypes with 3C-SiC as the most stable phase, which is in agreement with low-temperature experimental results. Quasiparticle band gaps computed with both the single-shot G0W0@PBE and the partially self-consistent GW0@PBE formulations quantitatively match well with the experimental values. The band structure of 31SSF reveals fault-induced sub-gap band splitting at the M point of 0.21 eV at the GGA level, which increases to 0.28 eV upon G0W0 correction. To our knowledge, this provides the first GW-level treatment of the 31SSF electronic structure in 4H-SiC. These results collectively provide a many-body perturbation theory (MBPT) level reference dataset for SiC polytypes and the commonly found stacking fault in 4H-SiC. Full article

A high-resolution unstructured-grid ocean model was used to investigate the generation, propagation, and dissipation of M₂ internal tides in the Luzon Strait and northeastern South China Sea, with the aim of clarifying how energy evolves across contrasting topographic regimes. Wave decomposition, harmonic and modal analyses, energy-budget diagnostics, and along-path tracking were applied to quantify the spatial distribution and modal evolution of internal-tide energy. The results show that the Luzon Strait double-ridge system is the primary source region, contributing approximately 4.826 GW of barotropic-to-baroclinic energy conversion, with the Lanyu Ridge (3.080 GW) exhibiting stronger conversion than the Hengchun Ridge (1.643 GW). The generated low-mode internal tides radiate mainly westward into the northeastern South China Sea, with energy progressively attenuated over the deep basin and continental slope. Energy-budget analyses indicate that the ridge region dominates generation, the Luzon Trough mainly supports transmission, and the deep basin and slope are associated with enhanced dissipation and scattering. Along-path energetic diagnostics quantitatively reveal a sequential depletion of mode 1 internal-tide energy in the vicinities of steep topography and internal-tide steepening zones, concomitant with a marked augmentation of mode 2 energy and intensified cross-frequency energy transfer. Specifically, within the deep basin of the South China Sea, the fractional contribution of mode 1 energy declines from 78.3% to 73.8% as the internal tide propagates from the abyssal to the shallower shelf-slope region, whereas that of mode 2 increases correspondingly from 18.2% to 24.3%. Moreover, pronounced internal-tide steepening is observed in the deep basin, and the spectrally integrated cross-frequency transfer coefficient reaches 0.32 in this area, substantially exceeding that in other regions. These findings suggest that topographic scattering, modal redistribution, and nonlinear interactions contribute substantially to regional internal-tide dissipation. Full article

Sustainable primary producer communities depend on a diverse pool of physiologically active cells surviving transport through sediment pore spaces. However, algal transport through saturated sediments remains a major knowledge gap in surface water–groundwater (SW-GW) interactions. In this study, vertical column experiments used a conservative tracer (NaCl) to establish hydraulic baselines. Three algal groups (green algae, cyanobacteria, and diatoms) were then tested across pH 8, 7, and 6, with recovery measured through biomass quantification, morphological identification, and post-run culturing. Green algae showed the highest mobility, with recovery increasing from 14.42% at pH 8 to 38.39% at pH 6 and retardation factors (R) of 1.33–1.40. Cyanobacteria peaked at neutral pH (29.50%) with higher retardation (1.60–2.31), while diatoms were strongly retained (≤5.72%) with high retardation (1.87–2.31). These differing transport patterns are primarily driven by morphological traits. Small, unicellular green algae are less susceptible to mechanical straining, enabling higher mobility. Conversely, cyanobacteria and diatoms experience stronger retention due to physical straining of their complex morphologies (filaments and chains) and enhanced surface adhesion from extracellular polymeric substances. A permutation-based two-way ANOVA indicated that the algal group significantly affected percent recovery (p = 0.0034), whereas neither pH (p = 0.166) nor the pH × algal group interaction (p = 0.076) was significant. Post-run culturing showed approximately 68% of inoculated genera persisted after passage, suggesting that saturated sediments can function as a biological “seed bank” for algal communities. These results highlight group-specific transport patterns in controlled sand columns and may inform future studies of algal persistence in natural surface water–groundwater systems; however, field-scale transport will also depend on sediment heterogeneity, flow conditions, and changing pore-water chemistry. Full article

Multi-Level Governance (MLG) frameworks effectively diagnose the complexity of regional renewable energy transitions but lack operational mechanisms for institutional implementation. This study develops a hybrid evidence-based architecture that integrates the Viable System Model (VSM) with computational intelligence and objective multi-criteria decision analysis. Methodologically, a systematic review following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) protocol of 339 peer-reviewed articles (2015–2025) feeds a Latent Dirichlet Allocation (LDA) model that extracts K = 30 strategic topics (semantic coherence $C_v$ optimized over K = 5–40), operationalizing System 4 environmental sensing. In parallel, a 1 km² pixel-based spatial model integrates a National Conflict Index (INC, 2019–2024) with technical feasibility layers (Global Wind Atlas v4.0, Solargis, Servicio Geológico Colombiano) and applies CRITIC (CRiteria Importance Through Intercriteria Correlation) objective weighting and TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) prioritization (System 3 control). Robustness is confirmed through $\pm 10$–$20\%$ weight perturbation (Spearman > 0.92). Empirically, the framework reveals a localization paradox: approximately 68% of optimal wind zones (>9 m/s at 100 m hub height) in the Colombian Caribbean overlap with the highest national conflict quartile, narrowing a theoretical capacity exceeding 100 GW (50 GW offshore wind, 30 GW onshore wind, 42 GW solar PV, 1.17 GW geothermal) to roughly 24 GW of governance-viable capacity. Scenario calibration (Accelerated 80/20, Balanced 50/50, Justice-Oriented 30/70 technical/conflict weighting) demonstrates that System 5 normative orientation materially reshapes territorial prioritization. The framework advances VSM from a qualitative diagnostic metaphor to a reproducible governance architecture for high-variety regional contexts. Full article

To analyze the impact of the expansion of grid connections for renewable energy sources, such as offshore wind power, and the application of energy storage technologies, such as hydrogen energy storage, on the energy system, this paper develops a dynamic penetration-rate-driven analytical framework (DPRAF). It analyzes the impact of relevant factors on the dynamic renewable energy penetration rate, changes in energy structure, electricity prices, and environmental governance costs. An improved two-stage optimization process comprising planning and verification is used to obtain system schemes and hourly penetration rates across various scenarios. The study found that the scale of wind power grid connection has a significant impact, while the application of hydrogen energy storage technology has a cumulative effect. This article also clarifies the transmission mechanism of the impact of renewable energy grid connection on market electricity prices in an imperfectly competitive market environment. Every 8 GW increase in grid-connected offshore wind capacity results in a rise of approximately HKD 0.004 per kWh in the electricity price under peak-time mode. The 16–24 GW range is viewed as a pragmatic compromise zone where the benefits of emission reduction remain commensurate with the associated environmental costs; however, once installed capacity exceeds 24 GW, electricity prices and the burden of mitigation measures experience a sharp, non-linear surge. The increase in grid connection scale will widen the environmental governance cost gap between liquefied hydrogen storage solutions and other solutions. The findings of this study further highlight the necessity of balancing benefits and overall costs in the development and application of renewable energy, providing a reference for future related work. Full article

Modern scientific research approaches to studying the hydrological cycle of water in nature, in addition to the mathematical modeling of hydrological–hydraulic processes that have expanded in recent years, increasingly include isotope hydrology on a global scale. This paper presents the preliminary results of research in the Vardar River basin. The research is in the field of isotope hydrology with the analysis of stable isotopes of hydrogen (δ²H) and oxygen (δ¹⁸O) in precipitation (P), surface water (SW) and groundwater (GW). For this purpose, a network for taking water samples in the Vardar River basin has been established. The isotopic composition of precipitation shows a relatively wide variability, with δ²H values ranging from −83.7‰ to −12.4‰ and δ¹⁸O values from −11.65‰ to −2.99‰. In contrast, groundwater samples exhibit a considerably narrower isotopic range, with δ¹⁸O values between −10.98‰ and −10.1‰ and δ²H values between −73.3‰ and −68.1‰. Surface water samples show δ¹⁸O values ranging from −10.7‰ to −9.11‰ and δ²H values from −70.6‰ to −61.6‰. The results of the study show that the waters in the Vardar River basin are predominantly of meteoric origin, with their isotopic composition being strongly influenced by climatic factors and altitude, varying from approximately 1400 m and 2000 m a.s.l. The study confirms that precipitation is the primary source of both surface and groundwater. Evaporation is the dominant process that modifies isotopic signatures during rainfall, surface runoff and groundwater recharge. Due to good fit and nearly parallel meteoric lines observed in the three different locations, preliminary LMWLs and RMWL were estimated. A similar isotopic composition of surface water (SW) and groundwater (GW) in some locations indicates the presence of a direct and active hydrological connection between these water bodies, which need to be investigated in more detail in future research. However, one of the groundwater sampling locations suggest more depleted isotopic composition, which is probably related to different recharge altitudes, but also possibly very interesting relationship between Vardar River, alluvial aquifers and karst aquifer in the Žeden massif. Full article

India’s solar photovoltaic expansion requires planning tools that can identify broad zones where new ground-mounted projects may merit detailed feasibility assessment. This study develops a GeoAI screening framework that combines cleaned solar-plant reference points, open remote-sensing predictors, machine-learning models, a tabular PyTorch deep-learning model, exclusion masking, spatial validation, external inventory checks, and explainable AI. Using 2848 cleaned utility-scale solar reference points and a 17,088-sample presence-background training matrix on a 0.05-degree grid, the workflow estimated relative solar-development suitability across India. The final four-member ensemble achieved ROC-AUC = 0.834, PR-AUC = 0.591, and F1 = 0.513 under spatial holdout validation; grouped spatial cross-validation produced mean ROC-AUC = 0.776 ± 0.082, PR-AUC = 0.505 ± 0.130, and F1 = 0.406 ± 0.102. After exclusion masking, the ensemble identified 145,391 km² of High or Very High suitability land, including 26,798 km² in the Very High class. Under the baseline 2.0 ha MW⁻¹ land-use assumption, developing 1–10% of the High/Very High screening area corresponded to approximately 73–727 GW of upper-bound planning-scale technical capacity. Independent World Resources Institute (WRI) and Global Energy Monitor (GEM) overlays indicated moderate spatial consistency, with 30.0–48.3% of external records falling in High or Very High classes. Sensitivity testing showed that probability cutoff, cropland treatment, and land-use assumptions strongly affect mapped extent and capacity scenarios, whereas reasonable slope-threshold changes had limited national effect. The results should therefore be interpreted as a reproducible screening and policy-prioritization surface, not as a parcel-level feasibility map. Full article

Normal contact stiffness of textured interfaces is controlled by the load-bearing contribution of deterministic texture and by the nonlinear response of rough load-bearing regions. This study formulates a hybrid deterministic–microlevel model that couples regular relief patterns—including dimples, grooves, periodic ribs and scraped high points—with a micromechanical representation of plateau roughness. Depending on texture topology and scale hierarchy, the microlevel response is represented either by a Greenwood–Williamson (GW) statistical contact model with a smooth elastic–plastic (EP) transition or by a fractal contact model. The deterministic level accounts for open-area fraction, texture depth and load redistribution, and it includes a finite-gauge spectral correction for periodic ribs and grooves to account for the finite measurement window. In a metallic dimple benchmark, the hybrid deterministic-texture/GW–EP formulation yields a mean relative error of 16.3% across all data points in the two selected textured series. In a saturated square-wave benchmark, the finite-gauge spectral correction yields a mean relative error of 10.37% for the independent patterned points. A compliance-based topology criterion is then established to determine, from open-area fraction, element depth, applied load and the ratio between texture period and plateau-roughness spacing, whether stiffness is governed primarily by deterministic texture, by micro-roughness or by their coupled response. The resulting formulation supports early-stage design exploration without requiring a full three-dimensional contact calculation at every parameter point. Independent periodic three-dimensional checks for circular-dimple cells showed that the finest FE solution agreed with the spectral prediction of the deterministic normal approach within 1.2%; the correction estimated by direct unilateral BEM changed total stiffness by no more than approximately 5% in the tested texture-influenced case. Full article

We present a rank-based method for detecting short-duration gravitational-wave transients in 46 days of coincident data from the first Advanced LIGO observing run (O1). The method applies a moving-window implementation of Chatterjee’s rank correlation coefficient to whitened interferometric sensor strain data. This produces a computationally efficient statistic sensitive to temporally ordered signal structure without relying on waveform templates. Compared with traditional excess power and coherent burst searches, the rank-based formulation is potentially less sensitive to certain non-Gaussian noise transients. Furthermore, it processes dual-detector data faster than real time on a single CPU core. We evaluate the method using 60 hardware injections from the O1 dataset, recovering 28 compact binary coalescence injections, primarily for events with a single-detector signal-to-noise ratio above approximately 13. The pipeline identifies 31 transient candidates, including the astrophysical event GW150914 and two instrumental glitches. Although the present implementation is less sensitive than established search pipelines, these results demonstrate the feasibility of the new method. Rank-based detection statistics provide a computationally efficient and complementary method for low-latency transient detection in interferometric sensor networks. Full article

In this study, an ultrasonic surface rolling process (USRP) was employed to enhance the surface performance of a GW63K-T6 magnesium alloy. The results show that the USRP induces a gradient-distributed {10–12} deformation twin structure in the surface layer, with twin density decreasing progressively from the surface inward. Following USRP treatment, surface microhardness increased by approximately 40%, yield strength (YS) by about 26%, and ultimate tensile strength (UTS) by roughly 11%. Corrosion resistance was also significantly improved, as evidenced primarily by a weight loss reduction of approximately 50% after 120 h of immersion corrosion and further supported by polarization curves with a positive shift in corrosion potential and a decrease in current density for the USRP-treated samples. The observed improvements in mechanical properties and corrosion resistance are closely associated with the gradient twin structure. These findings suggest that the USRP is a promising technique for the simultaneous enhancement in mechanical and corrosion properties of Mg-RE alloys, although further investigation is needed to fully elucidate the underlying mechanisms. Full article

This paper evaluates the potential for green hydrogen production in Tunisia using nearly 3 GW of renewable electricity distributed across four strategically selected sites: Haouaria, Zriba, Sbikha, and Feriana. These locations were chosen for their proximity to the Trans-Mediterranean (TransMed) natural gas pipeline linking Algeria to Italy, as well as their strong but underexploited solar and wind energy resources. Each site was optimized according to land availability and renewable energy potential: Haouaria is wind-dominant, Zriba employs a hybrid solar-wind configuration, Sbikha focuses on solar, and Feriana integrates both solar and wind over a large area. The analysis reveals a total green hydrogen production capacity supported by approximately 3.1 GW of installed renewable power, with a base-case LCOH ranging from $1.21 to $2.05 per kilogram. El Haouaria emerges as the most cost-effective site due to its highly favorable wind conditions, while the sensitivity analysis shows that LCOH can reach up to approximately $3.8 per kilogram under higher CAPEX assumptions. The findings underscore the viability of a multi-site development strategy and highlight northern Tunisia’s comparative advantage for low-cost green hydrogen production, thanks to its superior resource mix, existing infrastructure, and better water availability relative to Tunisia’s southern regions. Full article

Grain transparency (GT) is a key determinant of rice appearance quality and consumer preference, yet its genetic basis remains poorly understood. In this study, we evaluated GT in a panel of 450 rice accessions grown in two environments (Guangzhou and Yangjiang). Nineteen quantitative trait loci (QTL) for GT were identified by a genome-wide association study (GWAS), distributed across all rice chromosomes except chromosomes 2 and 12. Among these, four QTL (qGT-1b, qGT-3b, qGT-4b, and qGT-5b) were consistently detected in both environments. Notably, qGT-3b and qGT-5b co-localized with the grain shape genes GRAIN SIZE 3 (GS3) and GRAIN WIDTH 5 (GW5), respectively. For the novel and stable QTL qGT-4b, linkage disequilibrium decay analysis delimited an approximately 300 kb candidate region. Integrative transcriptomic and genomic analyses pointed to two candidate genes: LOC_Os04g40370 (OsFbx142), encoding an F-box domain protein, and LOC_Os04g40720 (OsSUBSrP1), encoding a subtilisin-like serine protease. Haplotype analysis further revealed that specific haplotypes of these genes were significantly associated with GT variation across environments. Our findings provide genetic insights into the regulation of rice grain transparency and offer candidate genes for further functional validation and potential application in improving rice appearance quality. Full article