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Disturbances drive large changes in plant composition and ecosystem functioning in drylands, but current understanding of how recovery following disturbance depends on the environment is limited due to challenges in analysing effects of disparate disturbances across abiotic gradients.We combined remote sensing and field observations across 5600+ km of natural gas pipeline corridors and adjacent undisturbed vegetation to investigate how recovery from a uniform, severe disturbance varied with factors that influence water availability in drylands.We found that recovery of net primary production (NPP) often remains incomplete, with only 42% of our sites projected to fully recover within 100 years. NPP recovery was quicker and more complete in regions that receive most of their annual precipitation at low temperatures and have fine‐textured soil; recovery of total shrub cover (median timing of 81 years) was faster on fine‐textured soils in locations that receive most of their annual precipitation at high temperatures. Locations with quick recovery of shrub cover were linked with a shift in dominant shrub species and incomplete NPP recovery.Synthesis. Recovery of NPP and shrub cover in drylands were driven by different environmental factors. For both NPP and shrub cover, locations with high pre‐disturbance values required more time to recover to adjacent undisturbed levels than locations with low pre‐disturbance values. Quick recovery of shrub cover or productivity was generally linked with a shift in dominant plant species or functional group. [ABSTRACT FROM AUTHOR]

The excavation and maintenance of buried natural gas pipelines can lead to deformation and stress redistribution of the pipelines and even cause secondary damage to the pipes with issues. To clarify the impact of excavation unloading on buried pipelines, this study established a finite element three-dimensional pipe-soil model, investigated the mechanical response of pipelines under layered excavation and evaluated various parameters impacting the response. The parameters analyzed include the diameter-thickness ratio of the pipe, excavation length and width, thickness of top covering soil, elastic modulus of soil, specific weight of soil and initial displacement of the pipeline. The study results showed that the pipeline bulges upwards during excavation unloading, the pipe top in the middle is under tension, and the bottom of the pipe is under compression. Therefore, the axial stress and vertical displacement both increase first and then decrease, and they are distributed symmetrically along the pipeline axis; excavating the initially compressed pipeline leads to high strain areas in the pipeline and even local buckling. The response to slope excavation is more pronounced than that to straight trench excavation; the additional response of the pipeline increases with the increase of diameter-thickness ratio, excavation width, thickness of pipe top covering soil and specific weight of soil, but it decreases with the increasing soil elastic modulus. The additional response is closely related to excavation length and the initial displacement. The results of this study can provide a reference for pipeline construction, maintenance, and safety assessment. [ABSTRACT FROM AUTHOR]

Natural gas pipelines are exposed to complex production and transportation environments, leading to blockages of varying compositions and forms due to various factors. This paper proposes a pressure pulsing wave‐based pipe blockage detection method, and a series of pipeline blockage detection experiments of different materials are carried out, including hydrate blockage, ice blockage, paraffin blockage, and water blockage. Through the blockage detection calculation theory and the reflection and transmission characteristics during pressure wave emission, the blockage position, length, and section blockage rate under different blockage materials are obtained, and the influence of different blockage materials on the reflection and transmission signal characteristics of the pressure pulse wave is analyzed. The results show that the solid blocking material does not noticeably impact the reflectivity and reflective properties of pressure waves, and different cross‐sectional shapes have a noticeable impact on the reflectivity of the pressure wave. The reflected wave waveform of the liquid blockage material is visible but irregular. The average error of blockage location is 0.78%. [ABSTRACT FROM AUTHOR]

The use of existing natural gas pipelines for the transport of hydrogen/natural gas mixtures can achieve large-scale, long-distance and low-cost hydrogen transportation. A jet fire induced by the leakage of high-pressure pure hydrogen and hydrogen-blended natural gas pipelines may pose a severe threat to life and property. Based on the Abel–Nobel equation of state and a notional nozzle model, an equivalent pipe leakage model is established to simulate high-pressure pipeline gas leakage jet fire accidents. Large-scale high-pressure hydrogen and natural gas/hydrogen mixture jet fires are simulated, showing the jet impingement process and obtaining an accurate and effective simulation framework. This framework is validated by comparing the simulated and experimental measured results of flame height, flame appearance and thermal radiation. Several combustion models are compared, and the simulated data show that the non-premixed chemical equilibrium combustion model is superior to other combustion models. The influence of the pipe pressure and the hydrogen blending ratio on the consequences of natural gas/hydrogen mixture pipeline leakage jet fire accidents is explored. It is found that when the hydrogen blending ratio is lower than 22%, the increase in the hydrogen blending ratio has little effect on the decrease in the thermal radiation hazard distance. [ABSTRACT FROM AUTHOR]

This article presents a comprehensive improvement in the experimental analysis of cracking processes in smooth and sharp V-notched samples taken from gas transport pipelines, utilizing the acoustic emission (AE) method. The research aimed to establish a robust correlation between the failure mechanisms of uni-axially tensile samples and the distinct characteristics of AE signals for enhanced quality management in pipeline integrity. The study encompassed materials from two different straight pipe sections, encompassing both long-term used materials and new, unused materials. Through the application of the k-means grouping method to AE signal analysis, we achieved the identification of AE signal parameters characteristic of various stages of the material destruction process. This advancement introduces a significant improvement in monitoring and managing the operational safety of pipeline networks, offering a methodology that leverages advanced acoustic emission signal analysis. The outcomes present significant implications for the pipeline industry by proposing methods to enhance safety systems and more effectively manage the integrity and quality of gas infrastructure. [ABSTRACT FROM AUTHOR]

Nowadays, with the rapid development of industrial Internet technology, on the one hand, advanced industrial control systems (ICS) have improved industrial production efficiency. However, there are more and more cyberattacks targeting industrial control systems. To ensure the security of industrial networks, intrusion detection systems have been widely used in industrial control systems, and deep neural networks have always been an effective method for identifying cyber attacks. Current intrusion detection methods still suffer from low accuracy and a high false alarm rate. Therefore, it is important to build a more efficient intrusion detection model. This paper proposes a hybrid deep learning intrusion detection method based on convolutional neural networks and bidirectional long short-term memory neural networks (CNN-BiLSTM). To address the issue of imbalanced data within the dataset and improve the model's detection capabilities, the Synthetic Minority Over-sampling Technique-Edited Nearest Neighbors (SMOTE-ENN) algorithm is applied in the preprocessing phase. This algorithm is employed to generate synthetic instances for the minority class, simultaneously mitigating the impact of noise in the majority class. This approach aims to create a more equitable distribution of classes, thereby enhancing the model's ability to effectively identify patterns in both minority and majority classes. In the experimental phase, the detection performance of the method is verified using two data sets. Experimental results show that the accuracy rate on the CICIDS-2017 data set reaches 97.7%. On the natural gas pipeline dataset collected by Lan Turnipseed from Mississippi State University in the United States, the accuracy rate also reaches 85.5%. [ABSTRACT FROM AUTHOR]

Copyright of Low-Carbon Chemistry & Chemical Engineering is the property of Low-Carbon Chemistry & Chemical Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article conceptualises one of the most important factors shaping the Russian–Turkish multidimensional partnership—the dynamics around energy. It seeks to answer the question: "To what extent does energy ensure cooperation in Russian–Turkish relations, despite current tensions?" The author argues that even though the two countries have had disagreements over each other's involvement in certain energy projects, their shared interests in energy have been strengthened by their interdependence and have led to a greater convergence, which in turn allows for cooperation. As a result, the energy sector serves as a mitigating factor in bilateral relations. The author focuses on Russian and non-Russian natural gas pipeline projects, using the interdependence theory as a theoretical framework. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Petroleum Research & Studies is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The growing importance of hydrogen as an energy carrier in a future decarbonised energy system has led to a surge in its production plans. However, the development of infrastructure for hydrogen delivery, particularly in the hard-to-abate sectors, remains a significant challenge. While constructing new pipelines entails substantial investment, repurposing existing pipelines offers a cost-effective approach to jump-starting hydrogen networks. Many European countries and, more recently, other regions are exploring the possibility of utilising their current pipeline infrastructure for hydrogen transport. Despite the recent efforts to enhance the understanding of pipeline compatibility and integrity for hydrogen transportation, including issues such as embrittlement, blend ratios, safety concerns, compressor optimisation, and corrosion in distribution networks, there has been limited or no focus on pipeline expansion options to address the low-energy density of hydrogen blends and associated costs. This study, therefore, aims to explore expansion options for existing natural gas high-pressure pipelines through additional compression or looping. It seeks to analyse the corresponding cost implications to achieve an affordable and sustainable hydrogen economy by investigating the utilisation of existing natural gas pipeline infrastructure for hydrogen transportation as a cost-saving measure. It explores two expansion strategies, namely pipeline looping (also known as pipeline reinforcement) and compression, for repurposing a segment of a 342 km × 36 inch existing pipeline, from the Escravos–Lagos gas pipeline system (ELPS) in Nigeria, for hydrogen transport. Employing the Promax® process simulator tool, the study assesses compliance with the API RP 14E and ASME B31.12 standards for hydrogen and hydrogen–methane blends. Both expansion strategies demonstrate acceptable velocity and pressure drop characteristics for hydrogen blends of up to 40%. Additionally, the increase in hydrogen content leads to heightened compression power requirements until approximately 80% hydrogen in the blends for compression and a corresponding extension in looping length until around 80% hydrogen in the blend for looping. Moreover, the compression option is more economically viable for all investigated proportions of hydrogen blends for the PS1–PS5 segment of the Escravos–Lagos gas pipeline case study. The percentage price differentials between the two expansion strategies reach as high as 495% for a 20% hydrogen proportion in the blend. This study offers valuable insights into the technical and economic implications of repurposing existing natural gas infrastructure for hydrogen transportation. [ABSTRACT FROM AUTHOR]

Industrial accidents include fire, explosion, and toxic substance spread involving hazardous substances. They threaten the health of many people, cause permanent or long‐term pollution of the natural environment, cause a high degree of property damage, and require a large‐scale emergency response. Pipelines that transfer hazardous chemicals over a large area are risky for industrial accidents. In this study, we aimed to analyze the consequences of a possible industrial accident at the Edirne Ipsala compressor station in the trans‐Anatolian natural gas pipeline (TANAP). Analyses were carried out with the ALOHA software on two hypothetical scenarios: In Scenario 1, the chemical escapes from the pipe without the gas burning; and in Scenario 2, the chemical escapes from the pipe with the gas burning (jet fire). In the analysis of overpressure effects, TNT EM and TNO MEM were used besides the software. The largest effect distance (≈5000 m) was determined in the flammable area as a result of Scenario 1, and the prominent hazard property of the chemical was supported. The overpressure effects obtained with TNO MEM and the software were compatible with each other, but the values obtained with TNT EM were less severe and quite different. In the analysis of overpressure effects, it is shown that the ALOHA software provided more conservative results and that buildings would collapse and lethal effects might occur at a distance of 1000 m from the source. ALOHA produced outputs integrated with GIS by providing thermal radiation and toxic effect threat zones as well as overpressure effects. ALOHA turns out to be a more convenient and practical tool for risk assessment studies and emergency plans. [ABSTRACT FROM AUTHOR]

With the rapid increase in urban gas consumption, the frequency of maintenance and repair of gas pipelines has escalated, leading to a rise in safety accidents during these processes. The traditional manual supervision model presents challenges such as inaccurate monitoring results, incomplete risk factor analysis, and a lack of quantitative risk assessment. This research focuses on developing a dynamic risk assessment technology for gas emergency repair operations by integrating the monitoring outcomes of artificial olfactory for gas leakage information and video object recognition for visual safety factor monitoring data. To quantitatively evaluate the risk of the operation process, a three-dimensional risk assessment model combining gas leakage with riskcorrelated sensitivity was established as well as a separate three-dimensional risk assessment model integrating visual risk factors with predictable risk disposition. Furthermore, a visual risk quantification expression mode based on the risk matrix-radar map method was introduced. Additionally, a risk quantification model based on the fusion of visual and olfactory results was formulated. The verification results of simulation scenarios based on field data indicate that the visual-olfactory fusion risk assessment method can more accurately reflect the dynamic risk level of the operation process compared to simple visual safety factor monitoring. The outcomes of this research can contribute to the identification of safety status and early warning of risks related to personnel, equipment, and environmental factors in emergency repair operations. Moreover, these results can be extended to other operational scenarios, such as oil and gas production stations and long-distance pipeline operations. [ABSTRACT FROM AUTHOR]

China Mohe Daqing Pipeline is the world first large diameter and positive temperature buried pipeline that crosses the unstable and discontinuous permafrost regions. The permafrost along the pipeline is characterized by its high temperature, large ice content, high sensitivity to external disturbance and extremely poor thermal stability. Thus, it is a great global engineering challenge to lay and operate a stable positive temperature pipeline under the harsh conditions of "permafrost land, frigid environment and fragile ecology" while, at the same time, protecting its fragile ecological environment. Herein, the characteristics of permafrost along the pipeline were systematically analyzed, and the current scientific and technical problems in the phases of pipeline designing, constructing and operating were put forward. This thesis made significant innovative breakthroughs in the coupling mechanism of permafrost and pipelines, the design and control of hydro-thermal stable environment for permafrost and pipeline, and the monitoring, prevention and control of permafrost and pipeline disasters, thus creating a complete set of key technical systems for pipeline construction and operation in frozen soil regions. Through analyzing the performance of this system in recent ten years, it is verified that the technical achievements served to the high-quality construction and stable operation of the pipeline. [ABSTRACT FROM AUTHOR]

Overtime, continuous research efforts have been devoted to investigating the effects of permanent ground deformation (PGD) on buried pipelines. These efforts have faced major uncertainties in the ground movement patterns that impose displacement-controlled loads on pipelines. This study presents a systematic review of the PGD patterns available in the literature for the analysis of buried pipelines, with particular emphasis on the PGD directions relative to pipeline axes. Depending on the directions, PGD patterns are divided into three groups: longitudinal, transverse and oblique. The relevant literature is organized into four main categories: experimental, numerical, analytical and probabilistic. Seven different PGD patterns (block, ramp, step, ridge, sinusoidal, asymmetric ridge, and asymmetric sinusoidal) available in the literature are discussed in this study. All these PGD patterns, except asymmetric sinusoidal, were applied in the longitudinal direction. In contrast, only three (block, sinusoidal and asymmetric sinusoidal) were applied transversely, which indicates a potential gap considering the randomness of PGD relative to pipeline axes. Besides, one additional PGD pattern (trapezoidal) is suggested in the present study based on the literature review. The findings of the present study show that 84 % of the reviewed cases considered either block or sinusoidal PGD pattern, while only 16 % considered the other PGD patterns (ramp, step, ridge, asymmetric ridge, and asymmetric sinusoidal). Almost all these 16 % reviewed cases assumed pipelines primarily as linear elastic materials. Based on these observations, the present study recommends a comprehensive study on the effects of all the mentioned PGD patterns on pipelines in all three directions. [ABSTRACT FROM AUTHOR]

Polyethylene (PE) pipes are widely used for natural gas distribution due to their good durability and low costs. To ensure the integrity of PE pipelines, it is crucial to develop a comprehensive understanding of pipe failure mechanisms and to recognize the benefits and limitations of different pipeline monitoring strategies. This review provides an overview of different types of pipe failures in the context of their response to operational loads and material degradation. It also covers the details of mechanical tests for predicting the long-term performance of pipes, theoretical models for studying defect growth, examines different defect detection methods, and concludes with an assessment of pipe repair techniques. The findings highlight the importance of investigating the effects of existing defects on the operational performance of the pipeline. This indirectly emphasizes the need to develop time- and cost-efficient strategies to detect defects in the early stages. There is a clear gap in the inclusion of PE aging effects in the lifetime performance models. In addition, given the large number of inspection techniques, a regulated selection of pipeline inspection methods is highly desired, specific to the defect type. Further research in advancing adhesive-based repair of incipient defects is crucial to prevent catastrophic defect growth. [ABSTRACT FROM AUTHOR]

The reliable operation of the natural gas pipeline system is directly related to natural gas supply security, and it is vital to determine the target reliability of the natural gas pipeline system when assessing whether the system is reliable. In this study, a methodology to determine the target reliability of natural gas pipeline system based on the risk acceptance criteria of pipelines is proposed, and the methodology consists of three parts. Firstly, the risk acceptance criteria of the natural gas pipelines are determined based on the existing standards. Secondly, the failure consequence model of natural gas pipelines considering the pipeline properties and surroundings is developed, and the corresponding allowable pipeline failure probabilities are calculated according to the risk theory. Finally, the evaluation model of the gas supply reliability for natural gas pipeline systems considering the unit's failure and hydraulic characteristics is developed, and the target reliability of natural gas pipeline systems is calculated by employing the allowable pipeline failure probabilities. Furthermore, a real natural gas pipeline system is employed to determine its target reliability, and the target value is compared with the actual value of the gas supply reliability. Based on the compared results, the corresponding measure to improve the gas supply reliability is proposed. [ABSTRACT FROM AUTHOR]

The electrochemical corrosion behavior of X70 pipeline steel under four different CO2 pressures was investigated by electrochemical test methods and scanning electron microscope analysis, based on the simulated environment of the extracted water of natural gas transmission pipeline in an oilfield of Xinjiang. Results showed that in simulated extracted water solutions with high chloride ion content, the electrochemical impedance spectra(EIS) and polarization curves indicated that the corrosion of X70 steel specimens became increasingly severe with increasing CO2 pressure(0.5, 1.0, 2.0, 3.0 MPa). The results of the loss-in-weight experiments showed that the corrosion rate of the X70 steel specimens increased with increasing CO2 pressure, with a maximum corrosion rate of 2.573 9 mm/a at a pressure of 3 MPa. In addition. the XRD results indicated that the corrosion products were mainly FeCO3. The SEM results showed that the pitting on the surface of the specimen became increasingly severe with increasing CO2 pressure, and the surface of the specimen became increasingly rough. These results were attributed to the effect of high pressure CO2 and pitting exacerbated by high Cl- concentrations. Hence, it could be found that high CO2 and Cl- had a serious damaging effect on X70 pipeline steel. This work provided reference and guidance for the prevention of this type of corrosion.

This review article provides a comprehensive overview of the fundamentals, modelling approaches, experimental studies, and challenges associated with hydrogen gas flow in pipelines. It elucidates key aspects of hydrogen gas flow, including density, compressibility factor, and other relevant properties crucial for understanding its behavior in pipelines. Equations of state are discussed in detail, highlighting their importance in accurately modeling hydrogen gas flow. In the subsequent sections, one-dimensional and three-dimensional modelling techniques for gas distribution networks and localized flow involving critical components are explored. Emphasis is placed on transient flow, friction losses, and leakage characteristics, shedding light on the complexities of hydrogen pipeline transportation. Experimental studies investigating hydrogen pipeline transportation dynamics are outlined, focusing on the impact of leakage on surrounding environments and safety parameters. The challenges and solutions associated with repurposing natural gas pipelines for hydrogen transport are discussed, along with the influence of pipeline material on hydrogen transportation. Identified research gaps underscore the need for further investigation into areas such as transient flow behavior, leakage mitigation strategies, and the development of advanced modelling techniques. Future perspectives address the growing demand for hydrogen as a clean energy carrier and the evolving landscape of hydrogen-based energy systems. [Display omitted] • Hydrogen gas characteristics are useful to model flow in pipelines. • Flammability, embrittlement, and leak risks associated with hydrogen pose challenges in transportation. • Temperature variation and pressure drop across critical components are important aspects of pipeline design. [ABSTRACT FROM AUTHOR]

The transport of hydrogen in used natural gas pipelines is a strategic key element of a pan-European hydrogen infrastructure. At the same time, accurate knowledge of the hydrogen quality is essential in order to be able to address a wide application range. Therefore, an experimental investigation was carried out to find out which contaminants enter into the hydrogen from the used natural gas pipelines. Pipeline elements from the high pressure gas grid of Austria were exposed to hydrogen. Steel pipelines built between 1960 and 2018, which were operated with odorised and pure natural gas, were examined. The hydrogen was analysed according to requirements of ISO14687: 2019 Grade D measurement standard. The results show that based on age, odorization and sediments, different contimenants are introduced. Odorants, hydrocarbons but also sulphur compounds, ammonia and halogenated hydrogen compounds were identified. Sediments are identified as the main source of impurities. However, the concentrations of the introduced contaminants were low (6 nmol/mol to 10 μmol/mol). Quality monitoring with a wide range of detection options for different components (sulphur, halogenated compounds, hydrocarbons, ammonia and atmospheric components) is crucial for real operation. The authors deduce that a Grade A hydrogen quality can be safely achieved in real operation. • Adequate hydrogen quality can be achieved in used natural gas pipes. • Grade A would be reached safely in normal operation of the sampled pipelines. • Detection of odorants from natural gas operations can be confirmed. • Sediments in the pipe are found to be the main source of contamination. • Newer pipes without solid deposits hardly carry any detectable impurities in hydrogen. [ABSTRACT FROM AUTHOR]

Limiting the rise in global temperature to 1.5 °C will rely, in part, on technologies to remove CO2 from the atmosphere. However, many carbon dioxide removal (CDR) technologies are in the early stages of development, and there is limited data to inform predictions of their future adoption. Here, we present an approach to model adoption of early-stage technologies such as CDR and apply it to direct air carbon capture and storage (DACCS). Our approach combines empirical data on historical technology analogs and early adoption indicators to model a range of feasible growth pathways. We use these pathways as inputs to an integrated assessment model (the Global Change Analysis Model, GCAM) and evaluate their effects under an emissions policy to limit end-of-century temperature change to 1.5 °C. Adoption varies widely across analogs, which share different strategic similarities with DACCS. If DACCS growth mirrors high-growth analogs (e.g., solar photovoltaics), it can reach up to 4.9 GtCO2 removal by midcentury, compared to as low as 0.2 GtCO2 for low-growth analogs (e.g., natural gas pipelines). For these slower growing analogs, unabated fossil fuel generation in 2050 is reduced by 44% compared to high-growth analogs, with implications for energy investments and stranded assets. Residual emissions at the end of the century are also substantially lower (by up to 43% and 34% in transportation and industry) under lower DACCS scenarios. The large variation in growth rates observed for different analogs can also point to policy takeaways for enabling DACCS. [ABSTRACT FROM AUTHOR]

In today's world, effective management and the use of spatial data are of great importance in many sectors. Industries such as land management, asset management, and infrastructure management are areas where spatial data are heavily utilized. Advanced technologies such as Geographic Information Systems (GISs) and Building Information Modeling (BIM) are used in the processes of collecting, analyzing, and managing geographically enabled data (geo-data). These technologies enable the effective processing of large datasets, improve decision-making processes based on geographic information, and facilitate more efficient collaboration across sectors. This study conducts an in-depth examination of the existing literature on asset management, infrastructure management, and BIM-GIS integration using bibliometric analysis and systematic literature review methods. Bibliometric analysis is employed to determine statistical values such as current research trends, frequently cited authors, most used keywords, and country performances in the relevant field. This study's results highlight future research trends and significant gaps in the areas of asset management, infrastructure management, natural gas pipelines, and BIM-GIS integration. In particular, this study demonstrates the critical importance of asset management and BIM-GIS integration for sustainable infrastructure design, construction, and management. In this context, attention is drawn to the importance of data standardization, digitization, systematic integration, and contemporary land management requirements. [ABSTRACT FROM AUTHOR]

Utilizing the existing natural gas grid presents a promising method for transporting hydrogen on a large scale. However, the effects of natural gas and its impurities on hydrogen-assisted cracking in pipeline steel have not been adequately studied. This study aims to investigate the fatigue performance of X80 pipeline steel in hydrogen-enriched natural gas (HENG) environments and in mixtures containing the impurity CO 2. This is achieved through fatigue crack growth rate (FCGR) tests and density functional theory (DFT) calculations. The experimental results show that the FCGR in H 2 is slightly faster than that in HENG, whereas it is slower than that in the N 2 /CO 2 /H 2 mixtures. The enhanced FCGR by CO 2 further increases with the increasing CO 2 content. DFT computational results indicate that the adsorbed CO 2 on the iron surface significantly accelerates the migration of H atoms from surface to subsurface. This promotes the entry of hydrogen into the steel. [Display omitted] • CO 2 promotes fatigue crack growth rate of X80 in the hydrogen environment. • Fatigue crack growth rate further enhances with the increasing CO 2 content. • CO 2 has little effect on the H 2 adsorption and dissociation on the Fe(110). • CO 2 accelerates the surface H atom migration to the subsurface of the Fe(110). [ABSTRACT FROM AUTHOR]

"The Greater Plains: Rethinking a Region's Environmental Histories" is an edited collection that challenges the dominant narrative of disaster and decline in the study of Great Plains environmental history. The book brings together scholars from various disciplines to explore themes such as technology, water, grasses, animals, energy, regionalism, mobility, and agricultural decline. While the collection lacks a clear thematic organization, it offers valuable insights into the complexity and nonlinearity of Great Plains environmental history. The inclusion of nonhistorians and interdisciplinary approaches adds depth to the field and indicates the direction in which it is heading. [Extracted from the article]

Although rapid transition away from fossil fuels will be required to limit warming to any agreed upon level, long-lived fossil energy infrastructure buildout continues largely unabated. Many nations around the world have laws requiring regulators to meaningfully assess potential climate impacts when reviewing proposals for new fossil fuel infrastructure projects such as oil and gas extraction leases, major transmission pipelines, and power plants. However, reviewing agencies often report lack of appropriate tools to objectively assess the climate impacts of individual fossil fuel infrastructure projects, and to determine the significance of these impacts. Here we present a novel methodology to fill this critical gap by providing a science-based decision support tool, a 'climate test', for use in determining an infrastructure project's carbon emissions significance. The climate test defines emissions significance quantitatively according to a project's consistency with region-specific constraints and characteristics of climate mitigation pathways, considering both emissions and energy systems characteristics over the project's lifespan. We showcase the tool here, using an example of a natural gas pipeline to explore how often and under what conditions the project would 'pass' the climate test with an emissions significance result of ≤1, which indicates alignment with a 1.5°C goal. For this project, less than 1.2% of 10,000 scenarios yielded significance values ≤1, suggesting a high likelihood that the project has a significant climate impact, a determination that would be robust to uncertainty for such a project. This emission-based metric represents a first step toward a broader framework to align project-level infrastructure decisions – including and beyond new fossil energy projects – with climate, as well as economic and societal, policy goals. This novel 'climate test' tool is suitable to support U.S. regulators in meeting their statutory requirements to assess the significance of climate impacts for fossil energy infrastructure projects on an individualized basis. While the tool was designed based on specific gaps identified in the U.S. system, it can readily be adapted for use in other non-U.S. regulatory contexts. Widespread implementation of such a climate test tool would help the US, and other nations that use it, to act consistently with their national and international climate commitments by aligning individual project-level decisions with pathways to limiting warming. By defining project significance in the context of both the emissions constraints and energy needs of a warming-limited world, this climate test tool provides decisionmakers with integrated and nuanced analytical information necessary to responsibly manage both energy and climate policy objectives. [ABSTRACT FROM AUTHOR]

Assessing the appropriateness of existing native plant materials can both determine which seed source to utilize for restoration projects, and identify locations for which new seed sources need to be developed. Here, we demonstrate an approach to meet these needs. This method identifies areas of high restoration need based on disturbance patterns, assesses the regional suitability of existing native plant materials based on climate similarity, and highlights geographic (and climatic) gaps where existing materials are likely unsuitable and where plant material development projects can be prioritized. We examined 12 high priority restoration species across the Colorado Plateau, a 38‐million‐ha region of the Intermountain West, United States to test our methodological pipeline. Fifty‐four percent of the Colorado Plateau is disturbed by livestock grazing, wildfires that have burned in the past 20 years, or energy production from oil and gas wells, natural gas pipelines, and coal mines. Of the 28 commercially available plant materials for six of the focal species, only 3 have climate similarity that encompass more than 50% of the species modeled habitat on the Colorado Plateau. Across all commercial materials, most species (10 of 12) do not have any suitable plant material for 70% or more of their geographic range on the Colorado Plateau. Of those areas identified as not having any suitable plant materials, 47–56% are also disturbed. Our method provides usable, flexible protocols and spatially referenced data sources for optimizing the planning of new native plant materials in any region where restoration is needed and spatial data are available. [ABSTRACT FROM AUTHOR]

The use of hydrogen-blended natural gas presents an efficacious pathway toward the rapid, large-scale implementation of hydrogen energy, with pipeline transportation being the principal method of conveyance. However, pipeline materials are susceptible to hydrogen embrittlement in high-pressure hydrogen environments. Natural gas contains various impurity gases that can either exacerbate or mitigate sensitivity to hydrogen embrittlement. In this study, we analyzed the mechanisms through which multiple impurity gases could affect the hydrogen embrittlement behavior of pipeline steel. We examined the effects of O2 and CO2 on the hydrogen embrittlement behavior of L360 pipeline steel through a series of fatigue crack growth tests conducted in various environments. We analyzed the fracture surfaces and assessed the fracture mechanisms involved. We discovered that CO2 promoted the hydrogen embrittlement of the material, whereas O2 inhibited it. O2 mitigated the enhancing effect of CO2 when both gases were mixed with hydrogen. As the fatigue crack growth rate increased, the influence of impurity gases on the hydrogen embrittlement of the material diminished. [ABSTRACT FROM AUTHOR]

Pipeline transportation is an efficient way to transport hydrogen on a large scale. However, many uncertainties lead to the failure of blended hydrogen natural gas (BHNG) pipelines, involving multiple consequence-based losses. The failure factors of BHNG pipelines have hybrid epistemic and aleatory uncertainties. The present study proposes a multidimensional integration approach to predict the failure risk of BHNG pipelines using fuzzy Bayesian networks (BN). The use of BN constructs topological structures to capture uncertain relationships among critical information. An expert-inspired method synthesizing fuzzy set theory can determine relative probabilities in the framework of cognitive uncertainties, and the analytic hierarchy process is introduced to capture the conditional probabilities. Multiple consequence dimensions were considered to incorporate safety barriers into the consequence risk analysis. The results demonstrate the objectiveness and effectiveness of multidimensional risk evaluation in addressing various risks. Failure risk can be mitigated and prevented by considering multidimensional impact assessment, which minimizes losses of leakage accidents. [ABSTRACT FROM AUTHOR]

With economic development and the burgeoning need for energy, numerous underground gas pipelines have been deployed for operation. Buried gas pipelines often suffer failures as a result of adverse factors, including corrosion, uneven subsidence, and damage caused by third parties. To investigate and predict the diffusion behavior following a natural gas pipeline leakage, Fluent software is utilized to develop a numerical model for the leakage and diffusion of high-pressure natural gas within a confined space. This model incorporates the Soave–Redlich–Kwong equation of state, which is widely recognized for its exceptional precision in characterizing the behavior of natural gas under high-pressure conditions. The study focuses on the analysis of leakage and diffusion behavior as well as the examination of how pipeline operating pressure and leakage diameter have an impact on the dispersion of leaked gas. Further, the prediction model for the diffusion distance of the hazardous area is developed, employing the least-square method and finite element calculations. The results show that, during the leakage process, a vortex and velocity region emerge, extending along the confined space. The farther away from the leakage hole above the pipeline, the higher the overall concentration of the gas. Moreover, the horizontal diffusion distance of gas at the bottom of the pipeline is considerably smaller than that above it. However, gas tends to readily accumulate in a high concentration area at the bottom of the pipeline. Elevating the leakage diameter and the operation pressure leads to a significant rise in gas concentration and the horizontal diffusion of the hazardous area. It is worth noting that the leakage diameter has a more pronounced effect on gas diffusion than does the pressure. The prediction model proposed in this study effectively anticipates the horizontal diffusion of the hazardous area within confined spaces. [ABSTRACT FROM AUTHOR]

The pipeline is the fundamental means of transporting natural gas between the reservoir and the point of consumption. Despite the systems' low cost and high reliability, potential pipeline failures would cause serious human injury, environmental impact, and financial costs. In order to reduce these damages, it is essential to study risk factors and investigate high-risk locations using existing risk factors. Spatial analysis is an appropriate method for studying environmental phenomena. Considering the extent of various factors influencing pipeline risk and their spatial dependence, we conducted a spatial analysis using ArcGIS to identify vulnerable areas and high-risk points in natural gas pipelines. For this purpose, the local influencing factors and their impact distance were determined by reviewing previous studies and then scored according to the risk level using the analytic hierarchy process (AHP) method. The risk of natural gas pipelines was then analyzed using these scores, the relationships developed, and the maps produced from the various factors. The results showed that most gas pipelines are exposed to various risks including dangers and geographical risks. Among these risks, faults play an important role, affecting about 97% of natural gas pipelines. In general, out of 13,875 km of general Iranian natural gas pipelines, 13,411 km are in various risk areas and 1,054 km are in high-risk areas, which are located at more than 4,300 points. The study of planned pipeline routes for future development also showed that these lines are located in relatively suitable areas. However, some changes to the routes could reduce the risks. Identifying the type and amount of risk on each pipeline helps experts choose a method with reasonable cost and sufficient efficiency for monitoring the pipeline according to the need. This paper is recommended for those involved with natural gas pipeline design and risk assessment. The "Introduction" section of this article is suitable for people who have just become familiar with this topic and want to get a general understanding of the topic as a whole and the previous studies done in this field. In this section, various monitoring methods of natural gas pipelines have been introduced, which helps the reader get familiar with these methods, their characteristics, and their operating range. In the "Methodology" section, due to the introduction, and the classification of risk factors, helps the reader to understand high-risk areas for the development of natural gas pipelines. This article presents a method to evaluate the risks identified and categorized by experts, first with the help of the analytic hierarchy process (AHP) and then with the help of maps and geographic information system (GIS) obtained from different points of the area. The review should be scored according to the level and type of risk and the AHP makes it possible to use experts' knowledge to rank the importance of different factors in comparison with each other. The maps obtained from this method can be used to improve the developing natural gas lines as well as the appropriate selection of monitoring methods to reduce the risks caused by natural gas pipelines. [ABSTRACT FROM AUTHOR]

Polyethylene pipeline is an essential infrastructure of gas distribution network, and there are some problems such as complex damage assessment and tedious assessment process. How to choose an effective damage assessment method for polyethylene pipelines is the focus of the implementation of the gas distribution network at present. In this paper, a nonlinear directional wave method is proposed to detect the damage of polyethylene pipeline by an acoustic wave, and the damage results of polyethylene pipeline are searched. The rationality of this method is verified by calculating the aerodynamic equation. The results show that the nonlinear fixed wave method can accurately determine the damage and crack propagation degree of the pipeline and simplify the damage assessment process, and the results are superior to the linear directional wave method. Therefore, the nonlinear directional wave can be used to assess the damage to ethylene pipelines in gas distribution networks, which has strong rationality and practicality and provides support for the actual pipeline damage assessment. [ABSTRACT FROM AUTHOR]

In the context of carbon neutrality and carbon peaking, in order to achieve low carbon emissions and promote the efficient utilization of wind energy, hydrogen energy as an important energy carrier is proposed to mix hydrogen and natural gas to form hydrogen-enriched compressed natural gas (HCNG). It is also injected into the natural gas pipeline network to achieve the transmission and utilization of hydrogen energy. At the same time, the participation of demand response is considered, the load's peak and trough periods are adjusted, and the large-scale consumption of renewable energy and the reduction in carbon emissions are achieved. First of all, a fine model of hydrogen production and hydrogen use equipment is established to analyze the impact of adding hydrogen mixing on the economy and the low-carbon property of the system. With green certificates and demand response, the utilization rate of hydrogen energy is improved to further explore the energy utilization rate and emission reduction capacity of the system. Secondly, on the basis of modeling, the optimal scheduling strategy is proposed with the sum of energy purchase cost, equipment operation cost, carbon emission cost, wind curtailment cost, and green certificate income as the lowest objective function. Considering the constraints such as hydrogen blending ratio and flexible load ratio of the pipeline network, a low-carbon economic scheduling model of hydrogen mixed natural gas was established. The model was linearized and solved by using MATLAB 2021a and CPLEX solver. By comparing different scenarios, the superiority of the model and the effectiveness of the strategy are verified. [ABSTRACT FROM AUTHOR]

The problem of hydrate formation and its attendant plugging effect on pipelines has remained a major challenge that the oil and gas industries are faced with during production. This problem is simply an issue affecting the oil and gas facilities both at drilling and production systems. As a result of this millions of dollars have been invested in remedial and preventive operations, therefore necessitating an in-depth study on the preventive methods. This study determines and validates existing postulations on favourable conditions at which hydrates form in transmission lines in a sampled Well-X, located in the Atlantic region. Measurements and experimentations were meticulously carried out on the sampled Well-X using methane gas and water at various conditions of pressure and temperature to determine the hydrate formation induction time using a stirred reactor. The result obtained in this study shows that the induction time at which hydrate starts to form in Well-X is at a pressure of 160 bar and temperature of 4°C. The obtained result confirms a pressure of 160 bar as against pressures of 120 bar and 135 bar and a temperature of 4°C as against 6°C as the induction time of hydrate formation. From the obtained result in this study, it is concluded that there is a need for a concerted effort to maintain stable pressure and temperature conditions of the flow systems. This study recommends that adequate provisions for an efficient flow assurance system with precise inhibitors in the right concentration and quality to mitigate the effects of hydrate should be made. [ABSTRACT FROM AUTHOR]

Natural gas is known as a widely used energy source in residential, business and industrial areas. During the transportation of natural gas by pipelines, accidents occur due to various reasons, which can also lead to gas output. These accidents are events that have the potential to pose important risks in terms of life and property safety, particularly in urban areas and surrounding of pipeline routings. In this study, accident scenarios were generated based on a natural gas distribution pipeline fire that occurred in Istanbul (NW Türkiye) on 28 April 2020 and the impact areas of the jet fire were calculated using the ALOHA program. The effects of source release factors (i.e., pipe length and diameter) and atmospheric conditions (i.e., wind speed, cloud cover, air temperature and relative humidity) on the thermal radiation threat distances associated with jet fire were calculated for the current and worst scenarios. As a result, it was found that pipe length and diameter have a significant effect on threat distances. In addition to the role of the synoptic circulation mechanism on the jet fire for the selected episodic event (position of low/high pressure centers), local atmospheric conditions also have an effect on the threat distance. From the modeling analysis, significant impact of wind speed, air temperature and relative humidity values on the threat distances were found. In the worst scenario, if there were strong northeasterly winds reaching 30.9 m per hour at the time of the jet fire, the threat distances would have been 21 m (red), 28 m (orange) and 42 m (yellow). This case shows that if a natural gas jet fire occurs under the influence of strong northeasterly winds (passing over the Black Sea without encountering any topographic obstacles), poisonous gas will be transported to long distances in a short time and will negatively affect social life and economy. [ABSTRACT FROM AUTHOR]

The most rapid and efficient method to transport natural gas from its source to its destination is through a pipeline network. The optimal functioning of control stations for natural gas pipelines depends on the use of electrical devices, including data loggers, communication devices, control systems, surveillance equipment, and more. Ensuring a reliable and consistent power supply proves to be challenging due to the remote locations of these control stations. This research article presents a case study detailing the design and dynamic modeling of a hybrid power system (HPS) to address the specific energy needs of a particular natural gas pipeline control station. The HOMER Pro 3.17.1 software is used to design an optimal HPS for the specified location. The designed system combines a photovoltaic (PV) system with natural gas generators as a backup to ensure a reliable and consistent power supply for the control station. Furthermore, it provides significant cost savings, reducing the cost of energy (COE) by USD 0.148 and the annual operating costs by USD 87,321, all while integrating a renewable energy fraction of 79.2%. Dynamic modeling of the designed system is performed in MATLAB/Simulink R2022a to analyze the system's response, including its power quality, harmonics, voltage transients, load impact, etc. The experimental results are validated using hardware in the loop (HIL) and OPAL-RT Technologies' real-time OP5707XG simulator. [ABSTRACT FROM AUTHOR]

This Article explores how the D.C. Circuit's decision in City of Oberlin, Ohio v. FERC (2022) (Oberlin II) will impact future natural gas pipelines and potentially even future hydrogen infrastructure. While the decision reinforced support for integrating North American natural gas infrastructure, given uncertainties in how the United States will regulate the emerging hydrogen industry, there is a chance that the decision could be more expansive than what initially meets the eye. By continuing down the path of supporting North American energy integration, Congress, federal courts, and administrative agencies will help prepare the United States for an uncertain energy future. Despite aiding the often-criticized natural gas industry, the Oberlin II decision is a win for North American energy integration, which will be needed to speed up any transition away from these fossil fuels. Thus, this Article argues that the Oberlin II decision and subsequent FERC decisions that take the Oberlin II holding a step further should be maintained and built upon. Tackling climate change and transitioning to cleaner energy sources will take bold steps and having administrative systems in place that support this transition is needed. [ABSTRACT FROM AUTHOR]

This study explores enhancing the resilience of electric and natural gas networks against extreme events like windstorms and wildfires by integrating parts of the electric power transmissions into the natural gas pipeline network, which is less vulnerable. We propose a novel integrated energy system planning strategy that can enhance the systems' ability to respond to such events. Our strategy unfolds in two stages. Initially, we devise expansion strategies for the interdependent networks through a detailed tri-level planning model, including transmission, generation, and market dynamics within a deregulated electricity market setting, formulated as a mixed-integer linear programming (MILP) problem. Subsequently, we assess the impact of extreme events through worst-case scenarios, applying previously determined network configurations. Finally, the integrated expansion planning strategies are evaluated using real-world test systems. [ABSTRACT FROM AUTHOR]

Shallow gas reservoirs play a crucial role in the gas hydrate system. However, the factors influencing their distribution and their relationship with the gas hydrate system remain poorly understood. In this study, we utilize three-dimensional seismic data to show the fluid pathways and shallow gas reservoirs within the gas hydrate system in the Qiongdongnan Basin. From the deep to the shallow sections, four types of fluid pathways, including tectonic faults, polygonal faults, gas chimneys, and gas conduits, are accurately identified, indicating the strong spatial interconnection among them. The gas pipes are consistently found above the gas chimneys, which act as concentrated pathways for thermogenic gases from the deep sections to the shallow sections. Importantly, the distribution of the gas chimneys closely corresponds to the distribution of the Bottom Simulating Reflector (BSR) in the gas hydrate system. The distribution of the shallow gas reservoirs is significantly influenced by these fluid pathways, with four reservoirs located above tectonic faults and polygonal faults, while one reservoir is situated above a gas chimney. Furthermore, all four shallow gas reservoirs are situated below the BSR, and their distribution range exhibits minimal to no overlap with the distribution of the BSR. Our findings contribute to a better understanding of shallow gas reservoirs and the gas hydrate system, providing valuable insights for their future commercial development. [ABSTRACT FROM AUTHOR]

The study of hydrate phase equilibrium is crucial for ensuring the safety of natural gas pipeline transportation and the process of hydrate recovery. While scientists typically focus on the chemical potential of hydrates, the role of gas solubility in hydrate phase equilibrium remains unclear, and this study fills this gap. This work investigated the solubility of gas at the equilibrium point of the hydrate phase through model calculations. Additionally, a new model of hydrate phase equilibrium is established based on the relationship between solubility. Firstly, a solubility model based on gas-liquid equilibrium theory showed higher prediction accuracy in comparison to the PR equation and Duan model and was then used to calculate gas solubility under hydrate phase equilibrium conditions. Afterwards, a novel model was developed to predict hydrate equilibrium state based on the relationship between gas solubility and hydrate phase equilibrium temperature, and it was further compared with the Chen-Guo model and CSMGem in terms of prediction accuracy under pure water and brine settings. The results showed: (a) The calculation deviation of the solubility model was 0.7-8.7% in pure water settings and 2.6-11.7% in brine settings; (b) A strong linear correlation between the phase equilibrium temperature of hydrates and gas solubility was also found; (c) This proposed model achieved over 10 times the accuracy of the Chen-Guo model and the CSMGem in predicting the phase equilibrium state of N2 and CO2 hydrates, and 3-10 times higher accuracy than that of the Chen-Guo model and CSMGem in brine. This work suggests that the gas solubility equilibrium theory can provide a more accurate prediction of hydrate states. [ABSTRACT FROM AUTHOR]

The addition of small amounts of certain gases, such as O 2 , CO, and SO 2 , may mitigate hydrogen embrittlement in high-pressure gas transmission pipelines that transport hydrogen. To practically implement such inhibition in gas transmission pipelines, a comprehensive understanding and quantification of this effect are essential. This review examines the impact of various added gases to hydrogen, including typical odorants, on gaseous hydrogen embrittlement of steels and evaluates their inhibition effectiveness. O 2 , CO, and SO 2 were found to be effective inhibitors of hydrogen embrittlement. Yet, the results in the literature have not always been consistent, partly because of the diverse range of mechanical tests and their parameters. The absence of systematic studies hinders the evaluation of the feasibility of using gas phase inhibitors for controlling gaseous hydrogen embrittlement. A method to quantify the effectiveness of gas phase inhibition is proposed using gas phase permeation studies. • Concise review of hydrogen embrittlement and control strategies in hydrogen pipelines. • Comprehensive literature review of gas phase inhibition of hydrogen embrittlement. • Inhibition effectiveness based on mechanical testing was evaluated and tabulated. • O 2 , CO or SO 2 are strong candidates for gas phase inhibition. • Typical gas odorants have no significant inhibition effect on hydrogen embrittlement. [ABSTRACT FROM AUTHOR]

Blending hydrogen into natural gas pipelines can affect their safety. Therefore, it is necessary to study the leakage and diffusion characteristics of hydrogen-blended natural gas (HBNG) pipelines. This paper establishes an integrated model of buried HBNG pipeline leakage and diffusion using programming for numerical simulation, and achieves the coupling of pipeflow-seepage-diffusion models. The PVT characteristics of the pipeline, concentration distribution, and hazard range of the underground and free space areas are studied. Effects of hydrogen blending ratio (HBR), soil permeability, and wind speed on leakage and diffusion characteristics are analyzed. The results show that the HBNG exhibits a larger pressure and flow rate fluctuation range after leakage but a lower mass flow rate and leakage mass flow compared to natural gas. With an increase in HBR, the risk index for the whole process also increases. The HBNG pipeline with 20% HBR has a higher underground pressure influence radius and underground hazard radius by 15.4% and 11.9% respectively, and the above-ground hazard height is 34.0% higher than the natural gas pipeline. In addition, the maximum hazard time is 33.3% faster. Increasing soil permeability significantly reduces the hazard range. Increasing wind speed dramatically reduces the hazard height. This study provides a transient computational model for the entire process of leakage and diffusion in the HBNG pipeline and offers theoretical guidance for the consequences of leakage. • The flow coupling among the pipeline, underground area, and free space is achieved after the leakage of HBNG. • An integrated computational model for leakage and diffusion is built. • The differences in characteristics after leakage between HBNG and natural gas are studied. • The impact of hydrogen blending ratio, soil permeability and wind speed on gas leakage and diffusion is analyzed. [ABSTRACT FROM AUTHOR]

This data report focuses on the heat transfer coefficient and pressure drop of natural gas flow condensation in spiral tubes. The report highlights the challenges posed by the complex heat transfer characteristics and phase change of natural gas condensation in spiral-wounded heat exchangers. It discusses the need for a specific condensation model for natural gas and describes the simulation methods used to determine heat transfer coefficients and pressure drops. The study reveals that the temperature of natural gas decreases as condensation progresses, and the heat transfer coefficient peaks near a vapor quality of 0.3. The authors recommend incorporating greater heat transfer area in regions of high vapor quality and below a vapor quality of 0.3 when designing spiral wound tube heat exchangers, as well as reducing the spiral winding radius to potentially improve heat transfer performance. [Extracted from the article]

Currently, mixing hydrogen into natural gas networks is the most cost-effective method for transporting significant quantities of hydrogen over long distances. However, after mixing natural gas with hydrogen, the properties of the mixed gas will change significantly, manifested as faster diffusion rate, increased combustion rate, and wider flammability limit. In this paper, a CFD numerical simulation method is used to establish a numerical model for the leakage and diffusion of buried hydrogen-blended natural gas (HBNG) pipelines, and the concentration diffusion trend and velocity flow field distribution of HBNG in soil under different leakage conditions are studied, as well as the alarm time when HBNG diffusion reaches the lower flammability limit (LFL) at the ground surface. At the same time, the effects of hydrogen blending ratio (HBR), pipeline operating pressure, soil porosity and leakage diameter on HBNG leakage and diffusion are investigated. The simulation results indicate that increasing the HBR will increase the diffusion rate of the mixed gas and reduce the LFL, resulting in a decrease of the alarm time. The increase of pipeline operating pressure and leakage diameter will increase the mass flow rate, and the increase of soil porosity will reduce the resistance when HBNG spreads in the soil. All three cases will significantly reduce the alarm time. The results of this study will provide some references for the emergency response work of buried pipeline leakage and the risk assessment of HBNG leakage and explosion. • A numerical model of leakage and diffusion in a buried hydrogen-blended natural gas pipeline is established. • The concentration diffusion trend of hydrogen-blended natural gas in soil under different leakage conditions are studied. • The effects of hydrogen blending ratio, pipeline operating pressure, soil porosity and leakage hole diameter on HBNG leakage and diffusion are investigated. [ABSTRACT FROM AUTHOR]

The high potential of hydrogen as a key factor on the pathway towards a climate neutral economy, leads to rising demand in technical applications, where gaseous hydrogen is used. For several metals, hydrogen-metal interactions could cause a degradation of the material properties. This is especially valid for low carbon and high-strength structural steels, as they are commonly used in natural gas pipelines and analyzed in this work. This work provides an insight to the impact of hydrogen on the mechanical properties of an API 5L X 65 pipeline steel tested in 60 bar gaseous hydrogen atmosphere. The analyses were performed using the hollow specimen technique with slow strain rate testing (SSRT). The nature of the crack was visualized thereafter utilizing μCT imaging of the sample pressurized with gaseous hydrogen in comparison to one tested in an inert atmosphere. The combination of the results from non-conventional mechanical testing procedures and nondestructive imaging techniques has shown unambiguously how the exposure to hydrogen under realistic service pressure influences the mechanical properties of the material and the appearance of failure. • Visualization of hydrogen induced crack propagation using μCT. • Orientation of cracks differs in hydrogen gas compared to inert gas atmosphere. • Spread of cracks differs in hydrogen gas compared to inert gas atmosphere. [ABSTRACT FROM AUTHOR]