Search Results (973)

Salt cavern Compressed Air Energy Storage (CAES) is one of the critical technologies for energy storage and an important infrastructure supporting the construction of new power systems and facilitating the achievement of the dual carbon goals. The salt rock resources in China are primarily composed of continental strata salt rocks, characterized by high heterogeneity, well-developed thin-layer interbedding, dissolution resistance among different lithologies, and significant creep variations. These features, to some extent, limit the improvement of wellbore construction accuracy, the reliability of abandoned well sealing, the safety of natural gas storage operations, and enhancements in gas injection–brine displacement efficiency. This study takes the continental bedded salt rock in the Dawenkou Basin as the research object and adopts a method combining theoretical analysis and field engineering verification to improve the systematic construction technology system, covering the whole process of drilling engineering, abandoned well plugging, the design of an injection and brine extraction device, and gas injection and brine drainage. The research results optimize four key technologies, including precise wellbore trajectory control, dual-section milling, and multi-stage redundant plugging of abandoned wells and long-term anti-corrosion completion with laser cladding, and dual-mode adaptive gas injection and brine drainage, and improve the technical system from wellbore construction to salt cavity formation. This study can provide valuable theoretical references and engineering demonstration guidance for underground space development projects in similar salt basins in China. Full article

Injecting CO₂ into gas reservoirs is a crucial approach for enhancing natural gas recovery and achieving CO₂ geological storage, where the gas–gas diffusion behavior between CO₂ and CH₄ directly influences gas mixing efficiency. Direct observation of the spatiotemporal evolution of concentration fields during diffusion remains insufficient. In this study, a gas–gas diffusion experimental system capable of multi-time and multi-space stratified sampling within a high-temperature high-pressure PVT cell was established based on real reservoir fluid compositions. Non-equilibrium diffusion experiments were conducted under different pressures, different initial CO₂ mole fractions, and different diffusion times. A diffusion model was developed according to Fick’s second law. The results suggest that the gas column can be divided into a natural gas zone, a transition zone, and a CO₂ zone by the dimensionless concentration gradient threshold. At 5 MPa, the transition zone width expands rapidly within the first 4 h (dimensionless width increases from 0 to 0.6902), after which growth slows. Increasing pressure significantly inhibits diffusion, reducing transition zone width and prolonging equilibration time. Rising initial CO₂ concentration also suppresses diffusion mixing, particularly in the later stage. Component profile analysis confirms that, under high pressures and high CO₂ concentrations, the diffusion flux across the interface is weakened. Compared to CH₄, the diffusion equilibration time of CO₂ is shorter and more sensitive to pressure changes. The obtained diffusion coefficients (CH₄: 2.92 × 10⁻⁸ to 4.79 × 10⁻⁸ m²/s; CO₂: 3.91 × 10⁻⁸ to 6.08 × 10⁻⁸ m²/s) are on the order of 10⁻⁸ m²/s, consistent with bulk-phase PVT literature data, validating the reliability of the experimental method and inversion model. This study lays an experimental foundation for predicting multi-component gas mass transfer under conditions of CO₂-enhanced gas recovery and CO₂ geological storage. Full article

As the core pillar of international trade, the global shipping industry has seen its carbon and pollutant emissions become a key challenge in global environmental governance. Statistics indicate that ship carbon emissions account for 3% of the world’s total anthropogenic CO₂ emissions, while contributing 20% of global NO_x and 12% of SO₂ emissions, posing a serious threat to coastal ecosystems and public health. In response to the International Maritime Organization (IMO) “Net Zero Framework” and national green shipping policies, the transformation of ship power systems toward low-carbon and zero-carbon operation has become an inevitable trend. This paper systematically reviews the research progress and application status of green energy materials for ships, focusing on the working principles, technical characteristics, and engineering application cases of solar photovoltaic (PV) materials, wind energy utilization technologies, fuel cell materials, and alternative clean energy fuels (e.g., liquefied natural gas (LNG), methanol, and hydrogen energy). It also discusses the integration mode and optimization strategy of multi-energy hybrid power systems. The research findings show that solar photovoltaic technology has achieved large-scale application in coastal ships; hydrogen fuel cells are suitable for long-range ocean navigation scenarios due to their high energy density; LNG and methanol have become the current mainstream alternative fuels, relying on mature infrastructure; and hybrid energy systems can significantly improve power supply reliability and emission reduction efficiency through multi-energy complementarity. Finally, aiming at the existing bottlenecks (e.g., cost, energy storage, and safety) of various technologies, future development directions are proposed. This study provides a reference for the technological breakthrough and engineering practice of green energy power systems for ships and contributes to the realization of the “carbon neutrality” goal in the global shipping industry. Full article

The energy transition of district heating systems in Poland requires the simultaneous consideration of energy efficiency, operating costs, technical feasibility, and local environmental constraints. This study addresses an identified gap in the literature by combining real operational time series from a municipal district heating system with time-resolved market signals and site-specific resource constraints in a single OPEX-based operational screening framework. A case study is conducted for the city of Ustka using a configuration-based comparison of hybrid supply systems that include a gas-fired combined heat and power (CHP) unit, air-source and ground-source heat pumps, thermal energy storage, and a peak-load boiler. The optimisation model was implemented in MS Excel using the GRG Nonlinear algorithm (Solver) and was driven by the district heating operational data for 2021–2022 together with electricity and natural gas prices from the Polish Power Exchange day-ahead market (TGE RDN), evaluated under both hourly and daily settlement assumptions. The results indicate an optimal capacity split of 1.2 MWel/1.3 MWth for the CHP unit and 1.5 MWel/3.0 MWth for the heat pump system, supported by a required peak boiler capacity of 8.23 MWth. Within the adopted OPEX-based assessment, the lowest value of the unit heat generation indicator was obtained for the CHP-led configuration with combined ground-source and air-source heat pumps (38.45–38.55 PLN/GJ). A distinctive element of the study is the explicit verification of whether an operationally favourable configuration remains practically feasible when local resource constraints are considered. The site assessment indicates limited practical feasibility of the borehole heat exchanger at the analysed location in Ustka, showing that the lowest OPEX result should not be interpreted as a final investment recommendation. The study provides a replicable approach for the Polish district heating operators to screen hybrid transition pathways under real market conditions and to avoid technology choices that are favourable in dispatch models but constrained in practice. From a sustainability perspective, the proposed framework supports more energy-efficient, resilient, and locally feasible district heating transition planning in municipal heat systems. Full article

Wetland system design, management and modelling to support ecosystem services during climate change have been evaluated in this structured and critical review. The focus was on non-tidal and agriculture-linked wetlands in oceanic, temperate and boreal regions. After applying 54 search terms using Google Scholar, 229 references have been cited. The review indicates that local wetland improvements rarely have a measurable impact on the overall watershed. Water can be retained mostly successfully in the landscape for relatively low- and medium-level rainfall. For large and less frequent floods, the concept of Retaining Water in the Landscape rarely applies. The success of compensation schemes for European and United States American farmers to control flood retention depends on financial status, farm size, age and the contract term duration. Ecosystem disservices such as greenhouse gas and nutrient release from ditches should be counteracted by rewetting. Combined water level and nutrient management supports carbon sequestration and protects watercourses from eutrophication. Restored wetlands usually reduce diffuse pollution and enhance biodiversity. The conservation of existing natural wetlands compared to restoring former wetlands is normally more effective regarding carbon storage. The value of sustainably managed wetlands is up to 50 times higher than the mean wetland restoration costs. Full article

This study evaluates fatigue crack growth in marine high-manganese steel LNG (Liquefied Natural Gas) storage tanks under cryogenic conditions. A 3D simulation framework using the M-integral for stress intensity extraction and the VCTD (Vertical Crack Tip Displacement) criterion for path prediction was developed. Parametric simulations showed that crack propagation is strongly directional, with the surface growth rate exceeding the depthwise rate. Fatigue life decreased with increasing initial crack surface length and maximum load but increased with crack inclination angle. In addition, the Mode I stress intensity factor along the depthwise path converged during propagation and rose sharply when the crack depth approached 90% of the wall thickness. An XGBoost-based dual-target model further achieved accurate prediction of crack depth and residual life. Full article

Existing structural health monitoring of LNG (liquefied natural gas) liquid storage tanks is strictly constrained by explosion-proof safety and engineering conditions, making it impractical to achieve full-domain coverage through dense sensor deployment. How to achieve effective coverage of structural seismic weak parts under limited measuring point conditions is the core issue for monitoring scheme optimization. This paper takes a practical large full-containment LNG storage tank project as the research object and proposes a targeted sensor deployment method based on finite element seismic response analysis: identifying structural seismic weak parts through refined finite element modeling and seismic response analysis, thereby achieving coverage of critical regions and improved monitoring efficiency under limited sensor constraints. The research approach is as follows: a finite element model of the LNG storage tank is established using ADINA software and verified through modal analysis combined with on-site ambient vibration testing, ensuring the accuracy and engineering applicability of numerical simulation. Typical seismic records including El Centro, Tangshan, and TAFT are selected, and seismic response analysis of the tank is carried out, clarifying the displacement response laws under different seismic waves and identifying the junctions of dome roof and tank wall, buttress columns and tank wall, and the upper and local areas of the tank wall as structural seismic weak parts. Based on the characteristics of these parts and on-site explosion-proof conditions, a four-measuring-point targeted monitoring sensor deployment scheme is formulated and applied in engineering. This research constructs a structural health monitoring method for LNG storage tanks featuring “structural model verification–weak part identification–monitoring scheme customization,” providing a new approach for tank monitoring under explosion-proof safety constraints and partially addressing the limitations of traditional empirical deployment methods. This study establishes a technical path covering the full cycle of routine operation, seismic response, and post-earthquake assessment, providing methodological support for the structural health monitoring of LNG storage tanks, and its core concepts can also serve as a reference for the structural health monitoring of similar large-scale thin-walled storage tanks. Full article

Underground Gas Storage (UGS) is transitioning from traditional fossil fuel peak-shaving facilities into comprehensive hubs for Terawatt-hour-scale Terawatt-hour (TWh) scale renewable energy storage. The unique physicochemical properties of diverse fluids, such as the negative Joule–Thomson coefficient of hydrogen (−0.03 K/bar), present complex engineering adaptability challenges. Since existing studies primarily focus on single mechanisms or specific geological types, this review integrates a unified engineering framework to evaluate the repurposing potential and retrofitting requirements of existing oil and gas assets. By compiling a property benchmarking matrix for methane, carbon dioxide, and hydrogen, the storage adaptability of various geological formations is summarized. Salt caverns exhibit strong adaptability to highly diffusive and reactive fluids due to their high salinity (exceeding 150 g/L) and mechanical stability, whereas porous media offer massive capacity (more than 10 times) but require overcoming severe biogeochemical obstacles. Based on thermo–hydro–mechanical–chemical–biological (THMCB) coupling mechanisms, an integrity evaluation system for artificial wellbore and natural geological barriers is systematically reviewed. Critical risks, including fatigue failure under high-frequency cyclic loading, material degradation, gas leakage, and indirect Global Warming Potential (GWP), are elucidated. A future evolution route integrating physical, digital, and policy dimensions is outlined. This roadmap emphasizes Hydrogen-Enriched Compressed Natural Gas (HCNG)synergistic storage, dynamic risk control utilizing digital twins and Artificial Intelligence (AI), and standardized Life Cycle Assessment mechanisms (LCA), providing a scientific basis for the sustainable transition of UGS facilities. Full article

Caraway essential oil (CEO) and chitosan-based nanoparticles incorporating CEO (CNPs CEO) were evaluated as natural preservatives for fresh pork sausages stored at +4 °C for five days. The chemical composition of CEO was characterized by gas chromatography–mass spectrometry (GC/MS) and gas chromatography with flame ionization detection (GC/FID); carvone (92.5%) and limonene (5.8%) were identified as dominant components. Eight experimental treatments were applied: control, CEO at 0.2, 0.4, and 0.6 mg/g, chitosan nanoparticles (CNPs), and CNPs CEO at 0.2, 0.4, and 0.6 mg/g. Encapsulation efficiency of CEO in chitosan nanoparticles was 67.7 ± 1.91%. Microbiological quality (total bacterial count (TBC), lactic acid bacteria, yeasts and moulds), lipid oxidation (TBARS), pH, and sensory attributes of raw and thermally processed sausages were monitored throughout storage. CEO reduced microbial growth and lipid oxidation in a concentration-dependent manner, while CNPs CEO formulations showed markedly superior performance. The CNPs CEO 0.6 mg/g treatment achieved the greatest inhibitory effect on all microbiological parameters, reducing TBC for 1.6 log CFU/g and limiting lipid oxidation, yielding final malondialdehyde values of 1.15 mg MDA/kg, approximately 50% lower than the control (2.18 mg MDA/kg). Sensory evaluation indicated that CNPs CEO-treated sausages maintained acceptable colour, odour, juiciness, texture, and overall acceptability throughout the storage period. The sample treated with CNPs CEO 0.6 mg/g remained above the acceptability level for all analyzed parameters for 5 days of storage, while the control became unacceptable for lipid oxidation on the fifth day and sensory unacceptable after the third day. These findings demonstrate that the application of CNPs CEO in sausage production enhances their stability, shelf life, and sensory characteristics, indicating a promising no-additive strategy in the industrial production of fresh pork sausages. Full article

Universities worldwide are increasingly committing to carbon neutrality; however, most institutional climate strategies treat operational emissions forecasting and ecosystem-based carbon sequestration as separate analytical domains, leading to inconsistencies in accounting boundaries, temporal alignment, and verification practices. This study develops and demonstrates an integrated LEAP–InVEST framework that explicitly links energy-system modeling with spatial ecosystem carbon accounting within a unified monitoring, reporting, and verification (MRV)-aligned structure. The framework combines the Low Emissions Analysis Platform (LEAP) for scenario-based greenhouse gas emissions modeling with the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model for spatial carbon storage assessment. A key methodological contribution lies in reconciling emission flows and carbon stock changes by converting carbon stock variations into annualized removal flows, thereby enabling consistent estimation of gross emissions, carbon removals, and net emissions while avoiding double counting across scopes. Using a university campus in Taiwan as a case study, a baseline inventory was established following ISO 14064-1 standards, and future emissions trajectories were simulated under Business-as-Usual and mitigation pathways through 2040. In parallel, land-use and land-cover data were used to quantify historical and projected carbon stocks across forest, grassland, agricultural, and built-up areas. Results indicate that electricity consumption constitutes the dominant emissions source, and that energy efficiency improvements, photovoltaic deployment, and green power procurement provide the largest mitigation potential. Although ecosystem carbon stocks remain substantial, their annual sequestration capacity offsets only a limited portion of projected emissions, reinforcing the importance of prioritizing emissions reduction before applying nature-based removals. The proposed framework provides a transferable methodological approach for institutional carbon neutrality planning by integrating emissions reduction and carbon sequestration within a coherent analytical system. By aligning energy modeling, ecosystem dynamics, and MRV principles, the framework enhances the transparency, credibility, and robustness of net-zero pathway assessment and is applicable to universities and compact urban systems seeking data-driven and verifiable decarbonization strategies. Full article

As critical infrastructure for seasonal natural gas peak-shaving, the operation of underground gas storage (UGS) must consider multiple factors including risk, economics, efficiency, and technology. Traditional UGS operation schemes are heavily dependent on subjective experience and lack intelligent methods to fully leverage historical data. This shortcoming leads to higher risks and increased compressor energy consumption. Taking S UGS as an example, the sensitivity factors of injection-production capacity are analyzed based on geological development and multi-cycle injection-production operation data. With injection-production rates as a decision variable and while considering safety and economic factors, objective functions and constraints are defined from the formation, wellbore, and surface. The proposed injection and production cycles are both 15 days, and the total injection and production volumes are 1200 × 10⁴ m³ and 800 × 10⁴ m³. An optimization model was constructed using the INSGA-Ⅱ and TOPSIS to determine the optimal gas injection-production volume allocation scheme. Compared with the initial scheme, the optimal injection-production volume allocation scheme reduces compressor energy consumption by 49.19% and 49.80% and formation pressure standard deviation by 78.88% and 77.21%, respectively. This effectively lowers injection-production energy consumption while improving safety, thereby ensuring the long-term safe and efficient operation of UGS. Full article

Large-scale and long-term hydrogen storage is one of the main obstacles to the wider use of hydrogen as a possible substitute for natural gas. A solution could be depleted natural gas fields, which have proven capacity and are already geologically prospected. However, part of this field remains occupied by residual natural gas, meaning that hydrogen is mixed with natural gas during storage and purification after extraction is therefore necessary. The aim of this study was to design and evaluate a hydrogen purification process for separating hydrogen from natural gas after extraction from a depleted natural gas field while maintaining the required hydrogen purity and recovery. Input data provided by Nafta a.s. were used for the mathematical simulation of hydrogen separation throughout a 150-day extraction period. A mathematical model of membrane separation and pressure swing adsorption (PSA) was developed. A single membrane stage was only able to operate effectively during the first 50 days of withdrawal while maintaining at least 80% hydrogen recovery. A two-stage membrane configuration achieved hydrogen purity above 98% with final recoveries above 80–85%, while the hybrid membrane–PSA system enabled hydrogen purity of 99.8% and total recovery of 82.5% on the last day of extraction. Full article

With natural gas demand growing rapidly in this century, solidified natural gas technology holds great potential for strengthening energy resilience and delivering secure global gas supply. However, this technology is still impeded by insufficient gas uptake capacity and sluggish hydrate formation rate. Environmentally benign peptides have recently emerged as a novel class of green hydrate promoters. Different from single amino acids, peptides exhibit significant structural diversity owing to their varying sequences and combinations of their constituent amino acid monomers, showing great potential in hydrate-based applications. In this work, a unique tripeptide promoter, L-glutathione reduced (GSH), was employed, and the thermodynamic influence factors in methane hydrate formation were systematically investigated. Furthermore, as a highly hydrophilic amino acid, L-arginine was chosen for a comparative kinetic investigation with extremely hydrophilic GSH. The results revealed that experimental pressure showed a strong effect on the methane uptake rate, while it presented little influence on final methane storage capacity. The initial temperature greatly affected the average induction time, the rate of hydrate growth, and the yields of hydrates promoted by GSH. Increasing temperature resulted in a significant reduction in both the hydrate formation rate and methane uptake at 3 h. Therefore, in the GSH-promoted hydrate formation process, suitable pressure and temperature should be carefully chosen for desirable hydrate performance. Furthermore, the initial 15 min hydrate formation rate of 0.3 wt% L-arginine is 52.4% lower than that of 0.3 wt% GSH. The final methane uptake of 0.3 wt% arginine is substantially smaller than that of 0.3 wt% GSH. Although both GSH and arginine exhibit strong hydrophilic properties, the tripeptide GSH is more effective than the amino acid arginine in enhancing methane hydrate formation. The insights gained from this work offer a theoretical foundation for the application of peptide-based promoters in solidified natural gas technology. Full article

Hydrogen is a key energy carrier for the transition to renewable energy, but its storage remains a major challenge, mainly due to the energy requirements for its production and to its low volumetric energy density under ambient conditions. Clathrate hydrates have recently emerged as a promising medium for gas storage, yet their potential for hydrogen storage is still underexplored. This study presents a comprehensive bibliometric analysis of hydrogen storage research, focusing on clathrate hydrates. The analysis, based on publications indexed in Scopus over the past decades, reveals that research on gas hydrates is mature and interdisciplinary, encompassing hydrate formation, thermodynamics, and production from natural reservoirs. In contrast, hydrogen hydrates remain a marginal and emerging research area, characterized by limited scientific output and weak connections to dominant storage strategies such as metal hydrides, metal–organic frameworks, and adsorptive materials. The results highlight key research gaps, including a limited understanding of formation kinetics, thermodynamic stability under practical conditions, and challenges related to scalability and system integration. These findings suggest that targeted research efforts addressing these bottlenecks could support the development of hydrate-based systems as complementary solutions within the broader hydrogen storage landscape. Full article

The global energy transition and the implementation of carbon capture, utilization, and storage (CCUS) strategies require energy-efficient and scalable CO₂ separation technologies. Mixed-matrix membranes (MMMs), combining polymer matrices with functional inorganic or hybrid nanofillers, have emerged as advanced separation platforms capable of surpassing the conventional permeability–selectivity trade-off observed in neat polymer membranes. This review critically evaluates recent developments in modern hybrid membranes for CO₂ separation from synthetic and industrial gas mixtures, including CO₂/N₂ (flue gas), CO₂/CH₄ (natural gas and biogas upgrading), and syngas systems. Particular emphasis is placed on MMMs incorporating covalent organic frameworks (COFs), metal–organic frameworks (MOFs), graphene oxide (GO), MXenes, transition metal dichalcogenides (TMDs), carbon nanotubes (CNTs), g-C₃N₄, layered double hydroxides (LDH), zeolites, metal oxides, and magnetic nanoparticles. Reported performance ranges include CO₂ permeability (P_CO2) typically between 100 and 800 Barrer, CO₂/N₂ selectivity up to 319, and CO₂/CH₄ selectivity up to 249, depending on filler chemistry, loading, and interfacial compatibility. The mechanisms governing gas transport—molecular sieving, selective adsorption, facilitated transport, and diffusion-pathway engineering—are systematically discussed. Key challenges addressed include filler dispersion, polymer–filler interfacial defects, physical aging, moisture sensitivity, oxidation (particularly in MXenes), and scalability toward industrial membrane modules. Future perspectives focus on sub-nanometer pore engineering, surface functionalization to enhance CO₂ affinity, controlled alignment of 2D nanosheets to promote directional transport, multifunctional core–shell and hollow structures, and the integration of computational modeling and machine learning for accelerated material design. Modern hybrid MMMs are identified as strategically important materials enabling high-efficiency CO₂ separation processes aligned with decarbonization and energy transition objectives. Full article