Search Results (1,022)

The increasing penetration of variable renewable energy sources (RESs) poses significant challenges to power system flexibility and reliability, particularly in systems with high solar generation. At the same time, existing Concentrating Solar Power (CSP) plants in Europe face declining economic viability due to high capital costs and the expiration of incentivized tariff schemes. This study proposes and evaluates a novel approach to repurpose CSP plants as flexible energy assets through the integration of cold thermal energy storage (CTES) within a Thermally Integrated Power-to-Heat-to-Power Energy Storage (TI-PTES) framework. The proposed system combines an ice/water-based cold storage with a CO₂-based refrigeration cycle to enhance the efficiency of the CSP steam cycle by reducing condenser temperatures, while also enabling temporal shifting of electricity consumption. A techno-economic optimization model based on PyPSA is developed to determine the optimal sizing and operation of the storage and refrigeration system under realistic load and electricity price conditions representative of the Spanish market. Results show that the integration of cold storage significantly alters system operation, shifting the chiller from a continuous demand-following mode to an intermittent, high-intensity regime. This leads to a reduction in annual operating expenditures by approximately 32% and an increase in annual profit and net present value (NPV), despite higher capital investment. While hourly net revenue becomes more volatile, with negative values during charging periods, cumulative annual performance improves due to effective temporal optimization. However, the absence of strong electricity price arbitrage and negative price signals limits the revenue potential of the storage system, which primarily acts as a cost-reduction mechanism. The findings demonstrate that cold thermal storage can successfully reposition CSP plants as flexible, value-generating assets in modern electricity systems. The proposed concept offers a promising pathway for extending the operational lifetime of existing CSP infrastructure while supporting higher integration of renewable energy sources. Full article

Tin–lead halide perovskite is a promising narrow-bandgap absorber for high-performance perovskite solar cells. However, the easy oxidation of Sn²⁺ and the resulting defect formation still limit these films’ quality and photovoltaic performance. Tin fluoride (SnF₂) is widely used as an antioxidant additive in Sn-containing perovskites, but its optimal concentration remains strongly dependent on the specific perovskite composition. Herein, we systematically investigate the influence of SnF₂ concentration on the film quality and device performance of methylammonium-free Sn–Pb perovskite solar cells. By varying the SnF₂ content from 0 to 15% relative to SnI₂, we find that an appropriate amount of SnF₂ can effectively improve the surface morphology, enhance crystallinity, promote preferred crystal orientation, and suppress defect-assisted non-radiative recombination. In particular, the film with 10% SnF₂ exhibits the smoothest surface, with a reduced root-mean-square roughness, enhanced photoluminescence intensity, and a lower trap density compared with the control films. As a result, the optimized device delivers a champion power conversion efficiency of 19.15%, significantly outperforming the control device. This work demonstrates the importance of SnF₂ concentration optimization and provides a useful guideline for improving MA-free Sn–Pb perovskite solar cells. Full article

Climate change politics has been largely analyzed through the lenses of a liberal international order. This is the most favorable approach, because liberalism contains a powerful universalistic strand, defends the rights of people, and engages in multilateral negotiations and agreements, which are important to deal with a global issue that requires intra- and intergenerational solidarity. Yet despite robust scientific consensus and decades of international multilateral agreements under the United Nations, global greenhouse-gas atmospheric concentrations continue to increase, and high fossil-fuel dependence persists. One may say that without those negotiations, the situation would be worse, but humanity is increasingly distant from complying with the objective of the United Nations Framework Convention on climate change (UNFCCC). The present work addresses climate change politics under liberal and neorealist international orders and follows the Mearsheimer hypothesis of a transition from a unipolar liberal order to a bipolar neorealistic bounded orders dominated by the US and China. The effect of international orders on sustainability and, more specifically, on climate change politics is analyzed with a methodology based on three structural determinants: (1) the world evolution of climate change variables; (2) primary-energy sources and critical minerals, and (3) climate change responses—mitigation, adaptation and climate geoengineering. The distinct energy and climate policies of the US and China are discussed using these structural determinants. US climate change policy appears to be less driven by climate observation, science and the severity of harmful impacts of climate change than by the vested interests of the fossil-fuel industry. It is argued that solar radiation manipulation (SRM) is a technological fix involving negative side-effects, uncertainties, risks and geopolitical implications, while lacking an agreed international governance framework. Potential deployment is more likely under a neorealistic international order, although it adds further uncertainty and risks without solving the climate change challenge. Full article

Ground-level ozone (O₃) has become a major air pollutant in China following PM_2.5, particularly in the southeastern coastal region, where the frequent interaction of typhoons and the subtropical high complicates pollution control. In this paper, spatial autocorrelation and a multiscale geographically weighted regression (MGWR) model were employed to estimate the spatiotemporal heterogeneity and driving mechanisms of O₃ in the Southeast Coastal urban agglomerations from 2015 to 2024. Temporally, the annual average O₃ concentration exhibited a fluctuating trend of an initial increase, followed by a decrease and a subsequent rebound. A bimodal monthly pattern was observed, with peaks in May–June and August–September and minima in winter. Diurnally, the concentration showed a consistent pattern of being higher in the daytime and lower at night, peaking in the afternoon, driven by solar radiation and temperature. Spatially, O₃ exhibited a distinct north–south gradient, with the highest in Jiangsu Province, followed by Shanghai, Zhejiang and Guangdong, and the lowest in Fujian. Significant spatial autocorrelation was detected, with hot spots in the Yangtze River Delta and cold spots in Fujian and adjacent areas. Seasonally, the most severe pollution with the greatest spatial heterogeneity, occurred in summer, contrasting with the uniformly low concentrations in winter. Compared with OLS and GWR, the MGWR demonstrated superior explanatory power. O₃ was jointly influenced by precursors, natural factors, and socioeconomic factors, with the influence intensity ranked as follows: NO₂ > average elevation > population density > annual precipitation> wind speed > built-up area > proportion of the secondary industry in GDP. Notably, the effects of NO₂, annual precipitation, and the proportion of the secondary industry exhibited strong spatial heterogeneity, operating at finer spatial scales. These findings provide scientific support for sustainable air quality management and region-specific O₃ control in southeastern coastal China. Full article

U.S. renewable energy consumption has expanded substantially over the past five decades, but this transition cannot be adequately characterized by aggregate growth alone. This study developed an integrated empirical, forecasting, uncertainty, reconciliation, scenario, and planning framework for U.S. renewable energy consumption using a complete monthly multisector panel from January 1973 through December 2025. The analytic dataset contained 3180 sector–month observations across 636 monthly periods and five reporting sectors: Commercial, Electric Power, Industrial, Residential, and Transportation. The framework combined data harmonization, mutually exclusive source-family construction, long-run trend analysis, source-mix diversification metrics, structural-regime diagnostics, sector–source panel analysis, rolling-origin forecast benchmarking, probabilistic interval assessment, hierarchical reconciliation, future scenario analysis, and decision-focused planning evaluation. Annual reported total renewable energy consumption increased from 2475.547 trillion Btu in 1973 to 7050.214 trillion Btu in 2025, equivalent to approximately 2.476 quadrillion Btu and 7.050 quadrillion Btu, respectively. The results show that U.S. renewable energy growth was also a source-mix transformation: the portfolio became less concentrated as wind, solar, transportation biofuels, renewable diesel, waste, and other emerging sources gained importance alongside legacy wood and hydroelectric power. Sector–source heterogeneity was substantial, with Electric Power, Industrial, and Transportation showing distinct renewable-source profiles. Forecasting performance depended strongly on model family, horizon, validation window, target group, and evaluation lens. Strong statistical baselines and feature-based tree models remained competitive or superior to several deep learning architectures, while time-series foundation models provided useful modern comparators but required calibration and horizon-specific interpretation. All five selected foundation model comparators completed successfully. ChronosBolt was the fastest and strongest completed foundation model comparator, followed in runtime by TimesFM, Moirai/Uni2TS, TimeGPT, and LagLlama; however, foundation model forecasts remained too smooth for peak-sensitive planning and did not displace the strongest feature-based tree models in point-forecast benchmarking. Probabilistic diagnostics showed that nominal coverage alone was insufficient because interval width, Winkler score, CRPS, and visual inspection revealed target-specific miscalibration, underforecast bias, and weak peak coverage. Hierarchical and decision-focused evaluation changed the model-selection narrative: bottom-up and reconciled hierarchical forecasts produced stronger planning-loss and planning-value profiles than many nominally advanced alternatives, while selected tree-based models were particularly useful for preserving source-share allocation. Scenario analysis showed that solar acceleration increased projected totals but also increased concentration and coherence divergence, whereas diversification reduced concentration but required wider uncertainty buffers. Overall, U.S. renewable energy consumption should be analyzed as a dynamic, diversified, hierarchical, and planning-sensitive system. The proposed framework provides a reproducible basis for evaluating renewable energy growth, source-mix evolution, forecast reliability, uncertainty, source allocation, scenario trade-offs, and planning value beyond single-model forecasting claims. Full article

This study presents the design and modeling of a first-of-its-kind experimental prototype integrating a high-temperature air-based Concentrated Solar Power (CSP) receiver with a diabatic Compressed Air Energy Storage (CAES) system. The prototype architecture and operating modes are defined, and a detailed thermal model of an Open Volumetric Air Receiver (OVAR) is developed and optimized, with emphasis on passive mass flow regulation under non-uniform solar flux. At nominal conditions (800 °C), the receiver achieves a predicted thermal efficiency of 81.6%. Transient simulations assess off-design dynamic behavior under realistic conditions, showing sensitivity to solar fluctuations and need for heliostat aiming strategies to reduce thermal non-uniformities and ensure stable outlet temperatures. For the CAES subsystem, a techno-economic analysis identifies high-pressure (300 bar) commercial gas cylinders as the most cost-effective aboveground storage solution, while discharge simulations yield a required storage volume of 4.8 m³. Finally, the complete piping and instrumentation diagram (P&ID) of the integrated system is presented, defining the experimental configuration. Overall, this work establishes the design basis for the future experimental demonstration of hybrid CAES-CSP operation for dispatchable renewable power generation and supports subsequent control development and scale-up analyses. Full article

Space missions working under harsh heliocentric conditions demand more efficient photovoltaics operating under high solar concentration, high temperatures, and harsh radiation conditions. Although most simulation work has been conducted using the terrestrial AM1.5 spectrum, AM0 high concentrators are of great importance to realistic satellite missions. Though III–V multijunction solar cells are currently the norm in space applications, their efficiency under extremely high solar concentration ratios is not yet optimized to support future space missions. This work designs and numerically optimizes a GaAs VTJ solar cell using SILVACO ATLAS software (5.40.0.R). In the optimization, the thickness of the front and back layers, as well as the doping profile within the emitter, base, and tunnel junction regions, were adjusted. The important PV semiconductor attributes, including the short-circuit current density (Jsc), open-circuit voltage (Voc), fill factor (FF), and efficiency (η), were examined over a concentration factor ranging between 1 and 10,000 suns. The efficiency of the optimized VTJ solar cell increased from 20.4% at 1 sun to 26.0% at 10,000 suns. This is mainly due to the near-linear increase in Jsc and the stable FF, which remains between 87% and 89%. In addition, the solar cell shows a steady increase in Voc between 1.85 V and 2.33 V. An optimized GaAs VTJ solar cell design is a promising component in future space missions, which require high power density and are suited to operating under high heliocentric orbits, such as in the Parker Solar Probe and solar-electric propulsion systems. Full article

The residential sector accounts for a significant portion of global energy demand, which can be met through sustainable alternatives such as solar energy. This study evaluated the energy, exergy, environmental, and exergy-sustainability performance of three waste heat recovery configurations (double-loop organic Rankine cycle—DORC, Kalina cycle—KC, and organic Rankine cycle—ORC) coupled to a supercritical CO₂ Brayton cycle with intercooling and reheating, designed to meet the demand of a residential complex of 120 homes in the Colombian Caribbean region, built with four different materials, using a concentrated solar power tower as the heat source. Mass, energy, and exergy balances were performed, along with a life cycle analysis, sizing the systems to supply a cooling load of 133 kW. The results show that the three configurations meet the required demand, with energy efficiencies above 50%: sCO₂-DORC (51.7%), sCO₂-ORC (51.61%), and sCO₂-KC (51.32%), with a maximum exergy efficiency for sCO₂-DORC (24.3%). The environmental analysis indicates that the construction phase accounts for more than 95% of total emissions. Overall, the results confirm the viability of these configurations for residential applications, promoting the integration of renewable energies and supporting the regional energy transition. Full article

Wind energy resource assessment in complex terrain regions requires high-resolution data and multidimensional risk evaluation beyond conventional wind speed climatology. This study uses a 40-year (1979–2018) WRF dynamical downscaling dataset assimilating over 2400 surface stations to assess wind power potential, long-term trends, diurnal characteristics, and extreme ramp events across nine terrain-defined wind zones in Xinjiang, Northwestern China. The capacity factor, equivalent full-load hours, and wind power density are computed at 100 m hub height and validated against 105 long-term stations. The domain-mean annual capacity factor is 0.08, but resources are concentrated in mountain-pass corridors where core-zone values reach 0.35–0.45. Seasonal asymmetry is pronounced: the windy season (April–August) contributes 57–69% of annual output depending on zone. Long-term trends are spatially differentiated, with a significant decline in southern basin zones and a significant increase in northern zones after 2006. Diurnal capacity factor profiles differ by zone type—nocturnal peaks in basin-margin corridors versus midday peaks in thermally driven passes—and remain phase-stable across four decades. Extreme ramp events concentrate in the windy season and decline in frequency after 2006, and sensitivity tests show that the main spatial pattern remains robust under 5%, 10%, and 15% hourly capacity factor change thresholds. These findings provide a quantitative basis for zone-specific wind power planning, storage sizing, and wind–solar complementarity strategies in arid continental regions with complex topography. Full article

CuSCN is a low-cost inorganic HTL with potentially better ambient stability than Spiro-OMeTAD according to literature. This study explores copper(I) thiocyanate (CuSCN) as a hole transport layer (HTL) to replace the conventional organic material Spiro-OMeTAD in antimony selenosulfide (Sb₂(S,Se)₃) solar cells. Numerical simulations performed with the Afors-het software reveal that the device structure FTO/CdS/Sb₂(S,Se)₃/CuSCN/Au incorporating CuSCN achieves improved interfacial energy band alignment. Specifically, the valence band offset (VBO) is reduced to −0.2 eV, which substantially enhances hole extraction efficiency and suppresses interface recombination. Through systematic optimization of key structural parameters, including the absorber layer thickness (350 nm), the CuSCN layer thickness (9 nm), and its p-type doping concentration (10¹⁹ cm⁻³), the device attains a maximum power conversion efficiency (PCE) of 12.03%. This work provides a theoretical foundation and a viable device design strategy for developing low-cost, highly stable, and efficient Sb₂(S,Se)₃ solar cells. Full article

Alkaline water electrolysis (ALK) is essential for renewable energy integration, yet traditional models using a fixed minimum operating power often overestimate low-load flexibility by neglecting state-dependent safety boundaries. This study develops an electro-thermal-mass multiphysics dynamic model that treats the transient hydrogen content in oxygen (H₂-in-O₂) concentration as a first-principles state variable. Based on a quasi-steady-state safety balance, a dynamic minimum operating power constraint is derived to replace empirical static limits. A key feature of this model is the explicit coupling of Arrhenius thermal diffusion and pressure-differential-driven permeation during load transients, allowing the safety threshold to respond to real-time system states. Year-round simulations of a 30 MW industrial system under a wind–solar time series reveal that thermal inertia, with a time constant of approximately 4.2 h, induces a sustained mismatch between low-power operation and high system temperature. Under high-temperature and rapid-ramp conditions, the dynamic safety lower bound reaches 28.2% of the rated capacity, exceeding the conventional 20% static threshold by 8.2 percentage points. This deviation results in 378.3 MWh of implicit curtailment and 60.5 h of additional downtime annually, leading to a green hydrogen production deficit of approximately 42.2 t/year. This research provides a theoretical foundation and technical reference for the optimal control and flexibility assessment of industrial-scale green hydrogen systems under fluctuating power supply conditions. Full article

We present a transdisciplinary Teaching–Learning Sequence (TLS) for lower secondary school students that integrates climate change education with the promotion of gender equality in science. The TLS connects theoretical understanding with practical engagement through laboratory demonstrations, simulations, and accessible experiments. The sequence addresses key topics in sustainability education, including incoming and outgoing radiation, the greenhouse effect, energy transformations, and energy sources, through activities involving the electromagnetic spectrum, infrared imaging, selective transparency, absorption, and albedo. It also includes inquiry-based explorations of electromagnetic induction, miniature hydroelectric and wind power systems, Stirling engines, photovoltaic and concentrated solar technologies, and combustion-related CO₂ acidification. A distinctive feature of the TLS is the explicit integration of the social dimension of sustainability through discussion of the Matilda Effect and the historical case of Eunice Newton Foote, with the aim of challenging persistent gender stereotypes in STEM. The intervention was implemented with 12–13-year-old students and evaluated through pre- and post-tests, written explanations, closed-ended questions, drawings, and the Draw-A-Scientist Test. The results indicate a significant improvement in students’ understanding of climate-related scientific concepts and in their critical awareness of misinformation and climate denial strategies. While the sequence did not significantly increase students’ engagement in climate action, the gender-focused activities promoted strong critical reflection on stereotypes and on the role of women in science. Full article

Water is an indispensable resource for the survival of all living organisms on Earth. However, many coastal villages continue to face challenges in accessing potable water, particularly during extended droughts. This comprehensive study evaluates the implementation and performance of a solar desalination system that employs photovoltaic (PV) panels and a parabolic solar concentrator to meet clean water demand in a drought-prone area of Indonesia. The system harnesses both solar-generated electricity and thermal energy to power an advanced desalination apparatus, effectively converting seawater into safe drinking water. Over a rigorous 4-month testing period, the device maintained an average steam outlet temperature of 105.9 °C, enabling a direct single-stage evaporation and condensation desalination process. Under optimal sunlight conditions, the system produced 1500 mL of purified water every 30 min, resulting in a total daily output of approximately 12 L (1500 mL × 8 cycles over 4 h). Laboratory analysis revealed a decrease in pH from 8.0 in raw seawater to 6.8 in treated water after post-treatment pH adjustment, meeting established safety standards for human consumption. Electrical conductivity measurements fell from 40–50 mS/cm to 480–500 µS/cm, confirming substantial salt removal. These results demonstrate the system’s capacity to generate potable water using sustainable energy sources and support circular economy principles by repurposing renewable resources for water desalination in water-scarce environments. Full article

To improve the flexibility and carbon reduction performance of coal-fired power plants, a solar-aided power generation (SAPG) system integrated with parabolic trough collectors and thermal energy storage (TES) was proposed and investigated using a combined Aspen Plus and System Advisor Model (SAM) framework. Two different integration schemes, namely SAPG-1 and SAPG-2, were evaluated under 100%, 75%, and 50% load conditions with a solar multiple of 2 and a TES duration of 6 h. The thermodynamic, economic, and environmental performances of the systems were comprehensively analyzed. The results show that TES significantly improves solar energy utilization, annual solar contribution, and system dispatchability. Compared with SAPG-2, SAPG-1 demonstrates superior thermodynamic and economic performance due to its lower boiler heat demand and more effective feedwater integration. At full load, the solar contribution of SAPG-1 with TES reaches 16.04%, while the annual solar energy production increases to 190.35 GWh with a capacity factor of 21.75%. In addition, TES integration effectively reduces the levelized cost of electricity and shortens the payback period under both CO₂ pricing and non-CO₂ pricing scenarios. The proposed SAPG framework demonstrates considerable potential for enhancing renewable energy utilization, operational flexibility, and economic feasibility in large-scale solar–coal hybrid power generation systems. Full article

To address the issues of high energy consumption, high carbon emissions, and the waste of associated energy (AE) in coal mine production, which severely hinder global sustainable development goals, this paper proposes a novel low-carbon economic collaborative optimal scheduling model for a coal mine integrated energy system (CMIES) oriented towards sustainable energy transitions. First, a refined utilization model for AE encompassing coal mine gas, ventilation air methane (VAM), and mine groundwater (GW) is constructed, and a tiered carbon emission trading mechanism (TCET) is introduced to constrain carbon emissions and promote ecological sustainability. Second, a concentrated solar power (CSP) plant is integrated to break the rigid “power determined by heat” constraint of a traditional combined heat and power (CHP) unit, thereby enhancing the system’s scheduling flexibility and renewable energy integration. Meanwhile, abandoned mines are retrofitted into solvent storage tanks to construct an integrated flexible carbon capture system (IFCCS), achieving sustainable reuse of mining wastelands. Finally, to tackle the multi-source, heterogeneous uncertainties on both the source and load sides, a hybrid risk assessment method combining information gap decision theory (IGDT) and conditional value at risk (CVaR) is proposed. Case study results demonstrate that, compared to traditional energy supply modes, the proposed model reduces carbon emissions and total costs in the mining area by 66.04% and 15.97%, respectively. This significantly improves resource utilization efficiency and ecological benefits, providing a highly viable pathway for the sustainable development and clean transition of coal mine operations. Furthermore, the proposed hybrid assessment method can effectively assist decision-makers in achieving a refined trade-off between operating costs and system robustness under varying risk preferences. Full article