Search Results (363)

Natural gas storage is an effective solution to address the energy supply–demand imbalance, and underground gas storage (UGS) is a primary method for storing natural gas. The overarching goal of this study is to monitor and analyze surface deformation at the Hutubi underground gas storage facility in Xinjiang, China, which is the largest gas storage facility in the country. This research aims to ensure the stable and efficient operation of the facility through long-term monitoring, using remote sensing data and advanced modeling techniques. The study employs the SBAS-InSAR method, leveraging Synthetic Aperture Radar (SAR) data from the TerraSAR and Sentinel-1 sensors to observe displacement time series from 2013 to 2024. The data is processed through wavelet transformation for denoising, followed by the application of a Gray Wolf Optimization (GWO) algorithm combined with Variational Mode Decomposition (VMD) to decompose both surface deformation and gas pressure data. The key focus is the development of a high-precision predictive model using a Gated Recurrent Unit (GRU) network, referred to as GWO-VMD-GRU, to accurately predict surface deformation. The results show periodic surface uplift and subsidence at the facility, with a notable net uplift. During the period from August 2013 to March 2015, the maximum uplift rate was 6 mm/year, while from January 2015 to December 2024, it increased to 12 mm/year. The surface deformation correlates with gas injection and extraction periods, indicating periodic variations. The accuracy of the InSAR-derived displacement data is validated through high-precision GNSS data. The GWO-VMD-GRU model demonstrates strong predictive performance with a coefficient of determination (R²) greater than 0.98 for the gas well test points. This study provides a valuable reference for the future safe operation and management of underground gas storage facilities, demonstrating significant contributions to both scientific understanding and practical applications in underground gas storage management. Full article

This paper proposes a ladder carbon trading-based low-carbon economic dispatch model for integrated energy systems (IESs), incorporating flexible load optimization and hybrid energy storage systems consisting of battery and thermal energy storage. First, a ladder-type carbon trading mechanism is introduced, in which the carbon trading cost increases progressively with emission levels, thereby providing stronger incentives for emission reduction. Second, flexible loads are categorized and modeled as shiftable, transferable, and reducible types, each with distinct operational constraints and compensation mechanisms. Third, both battery and thermal energy storage systems are considered to improve system flexibility by storing excess energy and supplying it when needed. Finally, a unified optimization framework is developed to coordinate the dispatch of renewable generation, gas turbines, waste heat recovery units, and multi-energy storage devices while integrating flexible load flexibility. The objective is to minimize the total system cost, which includes energy procurement, carbon trading expenditures, and demand response compensation. Three comparative case studies are conducted to evaluate system performance under different operational configurations: the proposed comprehensive model, a carbon trading-only approach, and a conventional baseline scenario. Results demonstrate that the proposed framework effectively balances economic and environmental objectives through coordinated demand-side management, hybrid storage utilization, and the ladder-type carbon trading market mechanism. It reshapes the system load profile via peak shaving and valley filling, improves renewable energy integration, and enhances overall system efficiency. Full article

Multi-energy systems (MESs) are designed to convert, store, and distribute energy to diverse end-users, including those in the industrial, commercial, residential, and agricultural sectors. This study proposes an integrated optimal planning optimization model for the techno-economic assessment of an MES integrated with power-to-gas (P2G) to meet electricity, heating, and cooling requirements while enabling sustainable energy solutions. The goal of the system optimal planning is to appropriately size the MES components to minimize the total planning costs. This includes not only the investment and operation costs but also the emissions cost and the cost of energy not supplied (ENS). The study implements P2G, electricity demand response (E-DRP), and thermal demand response (T-DRP), with four distinct operational scenarios considered for optimal planning, to evaluate the benefits of adopting MESs. A comprehensive validation study is presented based on a case study farm in Nigeria, with an MES investment model developed to assess feasibility. The results show that the integration of P2G with E-DRP and T-DRP gives the best operational scenario and planning cost for this farming application integration, leading to potential savings of up to USD 2.77 million annually from the proposed MES adoption. Full article

The “carbon neutral power generation” policy of the European Union requires the phasing out of fossil fuel power plants. These plants still play a crucial role in the energy mix in many countries; therefore, efforts are put forward to lower their CO₂ emissions. The available solution for an existing coal plant is the implementation of biomass co-firing, which allows it to reduce twice its carbon footprint in order to achieve the level of natural gas plants, which are preferable on the way to zero-emission power generation. However the side effect is a significant increase in the bulk fuel volumes that are acquired, handled, and finally supplied to the power plant units. A necessary extension of the complex logistic system for unloading, quality tagging, storing, and transporting biomass may increase the plant’s noise emissions beyond the allowed thresholds. For a comprehensive assessment of the concept of expanding the power plant’s biofuel supply system (BSS), a discrete simulation model was built to dimension system elements and verify the overall correctness of the proposed solutions. Then, a dedicated noise emission model was built for the purposes of mandatory environmental impact assessment procedures for the planned expansion of the BSS. The noise model showed the possibility of exceeding the permissible noise levels at night in selected locations. The new simulations of the BSS model were used to analyze various scenarios of biomass supply with regard to alternative switching off the selected branches of the whole BSS. The length of the queue of unloaded freight trains delivering an average quality biomass after a period of 2 weeks is used as a key performance parameter of the BSS. A queue shorter than 1 freight train is accepted. Assuming the rising share of RESS in the Polish energy mix, the thermal plant’s 2-week average power output shall not exceed 70% of its maximum capacity. The results of the simulations indicate that under these constraints, the biofuel supplies can be sufficient regardless of the nighttime stops, if 50% of the supplied biomass volumes are delivered by trucks. If the trucks’ share drops to 25%, the plant’s 2-week average power output is limited to 45% of its maximum power. The use of digital spatial simulation models for a complex, cyclical-continuous transport system to control its operation is an effective method of addressing environmental conflicts at the design stage of the extension of industrial installations in urbanized areas. Full article

To enhance the oxidative stability of aging diesel fuel stored in nuclear power emergency systems, we propose a novel hybrid optimization framework that integrates a Genetic Algorithm (GA), State-Space Network (SSN) modeling, and Computational Fluid Dynamics (CFD) simulation. Unlike previous studies that address treatment efficiency, flow optimization, or simulation separately, our method achieves real-time, simulation-informed optimization by embedding CFD-based performance evaluation directly into the GA fitness function. The SSN is employed to construct a comprehensive superstructure of feasible conditioning paths, which are dynamically explored and optimized by the GA under flow and boundary constraints. The CFD model, implemented via Ansys Fluent, accurately simulates the antioxidant mixing process in the tank and provides feedback on concentration uniformity at key monitoring points. The results demonstrate that the proposed framework reduces the conditioning time by 5.38% and significantly enhances the additive distribution uniformity. This work offers a generalizable approach for intelligent diesel upgrading in high-reliability energy systems and contributes a structured pathway for integrating data-driven optimization with physical process simulation. Full article

Hybrid Propellant Rocket Motors (HPRMs) have been advancing rapidly in recent years. These improvements are finally increasing their competitiveness in the global launch-vehicle market. However, some topics, such as the pre-combustion chamber design, still require more in-depth studies. Few studies have examined this subject. This work proposes a low-computational-cost algorithm that calculates the minimum pre-combustion chamber length, with a vaporization and feed-system coupled instability model. This type of analysis is a key tool for minimizing a vehicle’s size, weight, losses, and costs. Additionally, coupling with internal ballistics codes can be implemented. Furthermore, the results were compared with real HPRMs to verify the algorithm’s reliability. The shortened pre-chamber architecture trimmed the inert mass and reduced the feed-system pressure requirement, boosting overall propulsive energy efficiency by $\approx 8\%$ relative to conventional L*-based designs. These gains can lower stored-gas enthalpy and reduce life-cycle CO and CO₂-equivalent emissions, strengthening the case for lighter and more sustainable access-to-space technologies. Full article

To pursue the total decarbonization goal set at 2050, the introduction of hydrogen to replace the usage of fossil fuel in hard-to-abate industrial sectors is crucial. Hydrogen will replace natural gas in hard-to-abate sectors where natural gas is required to make heat necessary for the industrial process. Naturally, all this is worthwhile if hydrogen is produced following a green pathway, meaning that it is connected with renewable sources. In this manuscript, a techno-economic analysis related to a real case scenario is carried out. The real system addressed involves continuous high-temperature industrial furnace operation with a seasonally variable but stable thermal energy demand, representing typical conditions of hard-to-abate industrial processes. Solar photovoltaic panels combined with batteries are used to generate and store electricity that in turn is used to generate green hydrogen. Different scenarios are considered, including mixed natural gas/hydrogen, the seasonal variability of industrial needs, and the variability of solar production. The economic aspects considered include the usage of anion exchange membrane water electrolyzers (AEMWEs) to produce green hydrogen, the improvement in efficiency during operations (operational costs, OPEX), and the decrease in the AEMWE cost (Capital expenditures, CAPEX) that occur over time. The study shows that the hydrogen production cost could decrease from 12.6 EUR kg⁻¹ in 2024 to 9.7 EUR kg⁻¹ in 2030, with further reduction to 8.7 EUR kg⁻¹ achievable through seasonal blending strategies. CO₂ emissions are significantly reduced through partial displacement of natural gas with green hydrogen, highlighting the environmental potential of the system. Full article

This study presents a comprehensive dynamic model of a small-scale, solar-powered hydraulic gas compression energy storage system tailored for renewable energy applications. Addressing the intermittency of renewable energy sources, the model incorporates mass, momentum, and energy conservation principles and is implemented using GT-Suite simulation software v2025.0. The system, based on a liquid piston mechanism, was analyzed under both adiabatic and isothermal compression scenarios. Validation against experimental data showed maximum deviations under 10% for pressure and 5 °C for temperature. Under ideal isothermal conditions, the system stored up to 8 MJ and recovered 6.1 MJ of energy, achieving a round-trip efficiency of 76.3%. In contrast, adiabatic operation yielded 52.6% efficiency due to thermal losses. Sensitivity analyses revealed the importance of heat transfer enhancement, with performance varying by over 15% depending on spray cooling intensity. These findings underscore the potential of thermally integrated hydraulic systems for efficient, scalable, and cost-effective energy storage in distributed renewable energy networks. Full article

Multi-source systems are gaining attention as an effective approach to seamlessly incorporate renewable energies within electrical networks. These systems offer greater flexibility and better energy management possibilities. The considered multi-source system is based on a 50 MW wind farm connected to battery energy storage and electrolyzers through modular multi-level DC/DC converters. Wind energy systems interface with the DC-bus via rectifier power electronics that regulate the DC-bus voltage and implement optimal power extraction algorithms for efficient wind turbine operation. However, integrating intermittent renewable energy sources with optimal microgrid management poses significant challenges. It is essential to mention that the studied multi-source system is connected to the DC loads (modular electrolyzers and local load). This work proposes a new regulation method designed specifically to improve the performance of the system. In this strategy, the excess wind farm energy is converted into hydrogen gas and may be stored in the batteries. On the other hand, when the wind speed is low or there is no excess of energy, electrolyzer operations are stopped. The battery energy management depends on the power balance between the DC load (modular electrolyzers and local load) requirements and the energy produced from the wind farm. This control should lead to eliminating the fluctuations in energy production and should have a high dynamic performance. This work presents a nonlinear control method using a backstepping concept to improve the performances of the system operations and to achieve the mentioned goals. To evaluate the developed control strategy, some simulations based on real meteorological wind speed data using Matlab are conducted. The simulation results show that the proposed backstepping control strategy is satisfactory. Indeed, by integrating this control strategy into the multi-source system, we offer a flexible solution for battery and electrolyzer applications, contributing to the transition to a cleaner, more resilient energy system. This methodology offers intelligent and efficient energy management. Full article

Engineered wood products (EWPs) and timber buildings are increasingly recognised for their potential to reduce greenhouse gas emissions by storing biogenic carbon and replacing emission-intensive materials. This article systematically evaluates the carbon footprint (CF) of EWPs and timber buildings during the production stage (A1–A3), identifies key sources of variability, and extracts quantitative emission reduction metrics. Based on a review of 63 peer-reviewed studies, CF values vary widely, from −40 to 1050 kg CO₂eq m⁻² for buildings and 12 to 759 kg CO₂eq m⁻³ for EWPs, due to inconsistent system boundaries, functional units, and emission factor assumptions. Median CFs were 165.5 kg CO₂eq m⁻² and 169.3 kg CO₂eq m⁻³, respectively. Raw material extraction (50.7%), manufacturing (37.1%), and transport (12.2%) were the dominant contributors. A mitigation matrix was developed, showing potential reductions: 20% via transport optimisation, 24–28% through low-density timber, 76% from renewable energy, 11% via sawmill efficiency, 75% through air drying, and up to 92% with reclaimed timber. The geographic skew toward Europe and North America underscores the need for region-specific data. The findings provide actionable benchmarks and strategies to support carbon accounting, emissions modelling, and climate policy for more sustainable construction. Full article

The existence of a large number of abandoned salt caverns in China has posed a great threat to geological safety and environmental protection, and it also wasted enormous underground space resources. To address such problems, comprehensive utilization of these salt caverns has been proposed both currently and in the future, mainly consisting of energy storage and waste disposal. Regarding energy storage in abandoned salt caverns, the storage media, such as gas, oil, compressed air and hydrogen, have been introduced respectively in terms of the current development and future implementation, with site-selection criteria demonstrated in detail. The recommended burial depth of abandoned salt caverns for gas storage is 1000–1500 m, while it should be less than 1000 m for oil storage. Salt cavern compressed air storage has more advantages in construction and energy storage economics. Salt cavern hydrogen storage imposes stricter requirements on surrounding rock tightness, and its location should be near the hydrogen production facilities. The technical idea of storing ammonia in abandoned salt caverns (indirect hydrogen storage) has been proposed to enhance the energy storage density. For the disposal of wastes, including low-level nuclear waste and industrial waste, the applicable conditions, technical difficulties, and research prospects in this field have been reviewed. The disposal of nuclear waste in salt caverns is not currently recommended due to the complex damage mechanism of layered salt rock and the specific locations of salt mines in China. Industrial waste disposal is relatively mature internationally, but in China, policy and technical research require strengthening to promote its application. Furthermore, considering the recovery of salt mines and the development of salt industries, the cooperation between energy storage regions and salt mining regions has been discussed. The economic and environmental benefits of utilizing abandoned salt caverns have been demonstrated. This study provides a solution to handle the abandoned salt caverns in China and globally. Full article

In recent years, underground hydrogen storage (UHS) has become a hot topic in the field of deep energy storage. Green hydrogen, produced using surplus electricity during peak production, can be injected and stored in underground reservoirs and extracted during periods of high demand. A profound understanding of the mechanisms of the gas–water two-phase flow at the pore scale is of great significance for evaluating the sealing integrity of UHS reservoirs and optimizing injection, as well as the storage space. The pore structure of rocks, as the storage space and flow channels for fluids, has a significant impact on fluid injection, production, and storage processes. This paper systematically summarizes the methods for characterizing the micro-pore structure of reservoir rocks. The applicability of different techniques was evaluated and compared. A detailed comparative analysis was made of the advantages and disadvantages of various numerical simulation methods in tracking two-phase flow interfaces, along with an assessment of their suitability. Subsequently, the microscopic visualization seepage experimental techniques, including microfluidics, NMR-based, and CT scanning-based methods, were reviewed and discussed in terms of the microscopic dynamic mechanisms of complex fluid transport behaviors. Due to the high resolution, non-contact, and non-destructive, as well as the scalable in situ high-temperature and high-pressure experimental conditions, CT scanning-based visualization technology has received increasing attention. The research presented in this paper can provide theoretical guidance for further understanding the characterization of the micro-pore structure of reservoir rocks and the mechanisms of two-phase flow at the pore scale. Full article

The global campaign to reach net zero will necessitate the use of hydrogen as an efficient way to store renewable electricity at large scale. Methane pyrolysis is rapidly gaining traction as an enabling technology to produce low-cost hydrogen without directly emitting carbon dioxide. It offers a scalable and sustainable alternative to steam reforming whilst being compatible with existing infrastructure. The process most commonly uses thermal energy to decompose methane (CH₄) into hydrogen gas (H₂) and solid carbon (C). The electrification of this reaction is of great significance, allowing it to be driven by excess renewable electricity rather than fossil fuels, and eliminating indirect emissions. This review discusses the most recent technological advances in electrified methane pyrolysis and the relative merits of the mainstream reactor technologies in this space (plasma, microwave, fluidised bed, and direct resistive heating). This study also examines the economic viability of the process, considering energy costs, and the market potential of both turquoise hydrogen and solid carbon products. Whilst these technologies offer emission-free hydrogen production, challenges such as carbon deposition, reactor stability, and high energy consumption must be addressed for large-scale adoption. Future research should focus on process optimisation, advanced reactor designs, and policy frameworks to support commercialisation. With continued technological innovation and sufficient investment, electrified methane pyrolysis has the potential to become the primary route for sustainable production of hydrogen at industrial scale. Full article

Against the backdrop of the steady advancement of the national rural revitalization strategy and the dual-carbon goals, the low-carbon transformation of rural energy systems is of critical importance. This study first proposes a comprehensive architecture for rural energy supply systems, incorporating four key dimensions: investment, system configuration, user demand, and policy support. Leveraging the abundant wind, solar, and biomass resources available in rural areas, a low-carbon optimization model for rural energy system operation is developed. The model accounts for diverse load characteristics and the integration of elevated water towers, which serve both energy storage and agricultural functions. The optimization framework targets the multi-energy demands of rural production and daily life—including electricity, heating, cooling, and gas—and incorporates the stochastic nature of wind and solar generation. To address renewable energy uncertainty, the Fisher optimal segmentation method is employed to extract representative scenarios. A representative rural region in China is used as the case study, and the system’s performance is evaluated across multiple scenarios using the Gurobi solver. The objective functions include maximizing clean energy benefits and minimizing carbon emissions. Within the system, flexible resources participate in demand response based on their specific response characteristics, thereby enhancing the overall decarbonization level. The energy storage aggregator improves renewable energy utilization and gains economic returns by charging and discharging surplus wind and solar power. The elevated water tower contributes to renewable energy absorption by storing and releasing water, while also supporting irrigation via a drip system. The simulation results demonstrate that the proposed clean energy system and its associated operational strategy significantly enhance the low-carbon performance of rural energy consumption while improving the economic efficiency of the energy system. Full article

Motor vehicles in transport, as one of the important sectors of the economy, emit a significant amount of carbon dioxide and other products in the form of exhaust gases, which are harmful to human health. The emission of exhaust gases from motor vehicles is limited by appropriate regulations in accordance with environmental goals, such as the Paris Climate Agreement. Reduced emissions and fuel (energy) consumption is mainly achieved by applying modern technologies for the production of internal combustion engines; transitioning to cleaner fuels, such as renewable natural gas or biomethane; and using alternative propulsion systems. Biomethane stored in a liquid state in on-board reservoirs has advantages in truck transport, ships, and air traffic. The reason for this is due to the higher concentration of energy per unit volume of the reservoirs and the lower storage pressure and thus higher safety compared to the high-pressure storage option (compressed biomethane). The presented research is related to a proposition regarding the design of drive systems of city buses using biomethane as fuel in cases when fuel is stored on-board the vehicle as gas in a compressed aggregate state. In this study, the results of a calculation method regarding the roof-supporting structure of an experimental bus with gas reservoirs under higher pressure are discussed as well. This study also presents the possibility of reducing harmful emissions if biomethane is used instead of conventional fuels as a transitional solution to electric-powered vehicles. For the sake of comparison, it is suggested that the engaged energy and the amount of produced carbon dioxide emissions within the drive systems of different fuels are calculated according to the recommendations of the standard EN16258:2012. Full article