Natural Gas Distribution Network Research Articles

Analysis of The Feasibility of Hydrogen Injection in Pipeline Gas Distribution Networks

Analysis of The Feasibility of Hydrogen Injection in Pipeline Gas Distribution Networks

Analysis of Delta in-out for Irish natural gas distribution network

This article investigates the issue of Unaccounted for Gas (UAG) in the natural gas distribution network of Ireland, focusing on the DeltaIO (i.e. the difference between the gas entering and leaving the network). The study applies the DeltaIO methodology developed for Italian distribution networks to Gas Networks Ireland (GNI), the sole Distribution System Operator (DSO) in Ireland. The analysis covers the period from 2013 to 2019 and provides insights into the magnitude and trends of UAG in the Irish context. The results show that GNI's DeltaIO ranges from 0.93% to 1.57%, with an average of 1.15%. Comparisons with large Italian networks reveal higher DeltaIO values for GNI. The study demonstrates the compatibility of the DeltaIO methodology with the Irish distribution network and highlights the commercial implications of positive and negative DeltaIO values. The findings contribute to the understanding of UAG in the Irish natural gas sector and provide valuable insights for industry stakeholders and regulators.

Social and economic risk analysis of natural gas distribution networks

Social and economic risk analysis of natural gas distribution networks

MUNICIPAL INFRASTRUCTURE AT THE LEVEL OF PROTECTED NATURAL AREAS ROSCI0045 JIU CORRIDOR, BISTREȚ ROSPA0010 AND NATURAL RESERVES DRĂNC FOSSIL PLACE-2391 AND ZAVAL FOREST - IV.33 + A6

The paper aims to highlight the aspects related to the urban infrastructure for the protected areas ROSCI0045 Jiu Corridor, Bistreț ROSPA0010 and the Drănic Fossil Place-2391 and Zaval Forest Nature Reserves – IV.33+A6, given that they group a significant number of species of plant and animal origin. These protected areas play an essential role in biodiversity conservation at the level of the 56 ATUs (37 in Dolj County, 17 in Gorj County, one in Mehedinţi County, one in Olt County), on whose territory they are located. The paper refers to the drinking water distribution network, the sewerage network and the natural gas distribution network (including adjacent aspects related to them).The area has 740 km of city streets, of which 578 km modernized, 1971.2 km drinking water network, 936.0 km sewerage network, produces about 342 thousand cubic meters of water per day, achieving a daily consumption of 19,956 cubic meters. Within the area, there are 940.2 km of pipelines for natural gas distribution (two thirds located in the urban area), which facilitated a consumption of 133,040 thousand cubic meters of gas annually. The urban infrastructure improved during 2017-2021, but certain aspects related to it need to be properly analyzed in order not to have a high negative impact on the state of the environment.

A quantitative model to assess the human consequences of a natural gas pipeline rupture in urban distribution networks

Natural gas is known as a hazardous fuel that could cause human casualties, especially in urban areas. For this reason, assessing the consequences of natural gas pipeline ruptures is settled as an important element in determining the potential effects of such ruptures on human health and developing risk management programs for natural gas networks. Several efforts have been made in the literature to establish potential consequence areas; however, there are many limitations on the methodologies proposed so far; or alternatively, consequence analyses have been performed in specific cases using a defined location, but not along a natural gas distribution network. The model proposed in this research consists of two main components: (i) a spatial assessment of gas dispersion through the ALOHA software to obtain the potential impact areas, and (ii), the count of the number of individual people located within the potential impact areas through a geographic information system (GIS) model, which proves to be a valuable tool for assessing the consequences of natural gas distribution networks. The proposed model has been applied on a case study to validate the ability to quantify the number of people exposed per linear meter of pipeline, and provide the opportunity to relatively assess the level of consequences of the pipeline network.

A convex multi-objective distributionally robust optimization for embedded electricity and natural gas distribution networks under smart electric vehicle fleets

The indisputable environmental concerns have forced the imminent proliferation of renewable energy sources (RES) and electric vehicles (EV). However, the high penetration of such uncertain and variable sources, can pose significant challenges for maintaining supply–demand balance in electrical distribution networks (EDNs). To address these challenges, this paper presents a distributionally robust optimization (DRO) method for multi-objective scheduling in integrated electricity and natural gas distribution networks (IENGDNs). The proposed approach aims to minimize environmental-economic objectives while taking into account the high penetration of EVs and RESs. The impact of a smart EV charging strategy is evaluated to reduce operating costs and maximize the use of RESs. Additionally, demand response programs (DRPs) are used in the EDN to prevent overlapping of peak load hours between the EDN and natural gas distribution network (NGDN). Linepack technology is also used to store natural gas in NGDN pipelines, which increases the short-term flexibility of the entire IENGDNs. The proposed problem is mathematically structured as a second-order conical programming (SOCP) model to benefit from the reliable and efficient convex optimization solution. The simulations were conducted on a 123-EDN and a 40-NGDN systems. Different simulation cases show that the proposed economic-environmental framework can bring down the total emissions by 10.02%.

Intercomparison of detection and quantification methods for methane emissions from the natural gas distribution network in Hamburg, Germany

Abstract. In August and September 2020, three different measurement methods for quantifying methane (CH4) emissions from leaks in urban gas distribution networks were applied and compared in Hamburg, Germany: the “mobile”, “tracer release”, and “suction” methods. The mobile and tracer release methods determine emission rates to the atmosphere from measurements of CH4 mole fractions in the ambient air, and the tracer release method also includes measurement of a gaseous tracer. The suction method determines emission rates by pumping air out of the ground using soil probes that are placed above the suspected leak location. The quantitative intercomparison of the emission rates from the three methods at a small number of locations is challenging because of limitations of the different methods at different types of leak locations. The mobile method was designed to rapidly quantify the average or total emission rate of many gas leaks in a city, but it yields a large emission rate uncertainty for individual leak locations. Emission rates determined for individual leak locations with the tracer release technique are more precise because the simultaneous measurement of the tracer released at a known rate at the emission source eliminates many of the uncertainties encountered with the mobile method. Nevertheless, care must be taken to properly collocate the tracer release and the leak emission points to avoid biases in emission rate estimates. The suction method could not be completed or applied at locations with widespread subsurface CH4 accumulation or due to safety measures. While the number of gas leak locations in this study is small, we observe a correlation between leak emission rate and subsurface accumulation. Wide accumulation places leaks into a safety category that requires immediate repair so that the suction method cannot be applied to these larger leaks in routine operation. This introduces a sampling bias for the suction method in this study towards the low-emission leaks, which do not require immediate repair measures. Given that this study is based on random sampling, such a sampling bias may also exist for the suction method outside of this study. While an investigation of the causal relationship between safety category and leak size is beyond the scope of this study, on average higher emission rates were observed from all three measurement-based quantification methods for leaks with higher safety priority compared to the leaks with lower safety concern. The leak locations where the suction method could not be applied were the biggest emitters, as confirmed by the emission rate quantifications using mobile and tracer methods and an engineering method based on the leak's diameter, pipeline overpressure, and depth at which the pipeline is buried. The corresponding sampling bias for the suction technique led to a low bias in derived emission rates in this study. It is important that future studies using the suction method account for any leaks not quantifiable with this method in order to avoid biases, especially when used to inform emission inventories.

Consequences modeling and determining of safe distance in the natural gas pressure reduction station using PHAST software (Case study: Borumi station in Ahvaz)

Introduction: Gas pressure reduction stations are one of the most important parts of natural gas distribution networks. Risk assessment in operational units is a suitable method to assess risks, and their results can be used for management and decision-making regarding control and reduction of its consequences without critical concern. In other words, risk assessment is a process that identifies risks, assesses losses and determines risk characteristics. The present study aimed to model possible accidents, the subsequent evaluation of the consequences, and determination of safe boundaries in the suburban natural gas pressure reduction station located in the Bromi area of Ahvaz city using PHAST software.
 Materials and Methods: In this study, possible scenarios based on the investigated background and utilizing the process data of the studied gas pressure reduction station, such as temperature, gas pressure, gas analysis, and meteorological data, and also using Pasquil's classification of atmospheric conditions the safe boundaries in the suburban natural gas pressure reduction station was investigated using PHAST software version 22.8 and. For this purpose, 6 possible scenarios were investigated in the selected atmospheric classes as well as the worst possible conditions. The consequences were evaluated based on different states of gas discharge, gas release, flash fire, sudden fire, and explosion.
 Results: Based on the obtained results, the areas with high-risk potential were related to gas release and explosion, respectively. Also, the highest risk range belonging to scenario number five was reported for a gas explosion with atmospheric class F and wave intensity of 0.02068 bars and equivalent to 358.5 meters. In this range, according to the damage caused by the explosion, with a probability of 95%, without serious damage, 50% of the windows will be broken, and therefore it can cause human injuries. Based on this, the safe distance in this station was determined to be 358.5 meters.
 Conclusion: Based on concerns about the lack of risk assessment studies over the initial phases and during the operation of the station, the study shows that determining the safe boundaries and high-risk areas along with the priority of risk reduction is very necessary. It can be concluded that the modeling of accidents and the evaluation of the resulting consequences along with the determination of safe boundaries is one of the basic factors in the health of the working environment of personnel and the general public.

Real-time pipeline leak detection and localization using an attention-based LSTM approach

Long short-term memory (LSTM) has been widely applied to real-time automated natural gas leak detection and localization. However, LSTM approach could not provide the interpretation that this leak position is localized instead of other positions. This study proposes a leakage detection and localization approach by integrating the attention mechanism (AM) with the LSTM network. In this hybrid network, a fully-connected neural network behaving as AM is first applied to assign initial weights to time-series data. LSTM is then used to discover the complex correlation between the weighted data and leakage positions. A labor-scale pipeline leakage experiment of an urban natural gas distribution network is conducted to construct the benchmark dataset. A comparison between the proposed approach and the state-of-the-arts is also performed. The results demonstrate our proposed approach exhibits higher accuracy with AUC = 0.99. Our proposed approach assigns a higher attention weight to the sensor close to the leakage position, indicating the variation of data from the sensor has a significant influence on leakage localization. It corresponds that the closer to the leakage position, the larger variation of monitoring pressure after leakage, which enhances the detection results’ trustiness. This study provides a transparent and robust alternative for real-time automatic pipeline leak detection and localization, which contributes to constructing a digital twin of emergency management of urban pipeline leakage.

Examination of Condensation Liquid Formation in Istanbul Natural Gas Distribution Network

In this study, the formation of natural gas liquid in gas distribution lines, particularly at regional stations, service boxes, customer installations, and gas meters, was investigated. The study aims to address the problems associated with natural gas liquid formation, such as interruption of supply and decreased efficiency of combustion devices. The indirect measurement of the hydrocarbon dew point was analyzed using C6+ chromatograph data, and the model based on directly measured C6+ data were converted into C6/C7/C8 data by four different methods. As distinct from studies in the literature, this study experimentally determines the distribution of heavy hydrocarbons from C9 to C19 based on indirect methods for acquiring C8+ data and direct measurement of C6+ data. The hydrocarbon dew point temperature was calculated using the Peng–Robinson (PR) and Soave–Redlich–Kwong (SRK) equations of state. The results of the analysis performed on two city gate stations showed that the critical temperatures were 4.21 °C at a pressure of 10.81 bar and 8.27 °C at a pressure of 11.25 bar, respectively. These values were obtained from a model designed to determine the dew point temperature in the area where natural gas liquid formation was most prevalent. The experimental analysis and indirect measurements indicated the occurrence of a two-phase gas–liquid formation.

Reactive Processes for H2S Removal

Growing demand for renewables and sustainable energy production contributes to a growing interest in producing high quality biomethane from biogas. Despite having methane (CH4) as its main component, biogas may also present other noncombustible substances in its composition, i.e., carbon dioxide (CO2), nitrogen (N2) and hydrogen sulfide (H2S). Contaminant gases, such as CO2 and H2S, are impurities known for being the main causes for the decrease of biogas calorific value and corrosion, wear of pipes, and engines, among others. Thus, it is necessary to remove these compounds from the biogas before it can be used in applications such as electricity production, thermal purposes, and replacement of conventional fossil fuels in vehicles, as well as injection into natural gas distribution networks. In this context, the present work aimed to present a systematic review of the literature using the multicriteria Methodi Ordinatio methodology and to describe processes and materials for H2S removal. The discussion indicated new materials used, as well as the advantages and disadvantages observed and the limitations in industrial implementation.

A REVIEW OF NATURAL GAS-HYDROGEN BLENDING IN PIPELINE SUPPLY AND DISTRIBUTION

The reduction of greenhouse gases is an assumed objective of the European Community. Thus, in the future, natural gas transport and distribution pipelines will also have to deal with ensuring the transport of mixtures formed between hydrogen, biomethane and natural gas from fossil resources. Considering the increase in the amount of biomethane and the increase in the amount of green hydrogen produced, these fuels’s use in natural gas distribution networks is expected. The article presents an analysis of hydrogen production methods as well as numerical models of hydrogen transportation and mixing with natural gas. Also, there are presented the results obtained at the international level regarding the thresholds for the use of hydrogen in the fossil fuel of natural gas type, as well as the effects produced by the presence of this gas on the transport and supply systems. Numerical models of mixing and dynamic behavior of the new fuel obtained are also analyzed.

Dynamic Analysis of the Italian Gas Distribution Network

In this work, a dynamic analysis of a natural gas distribution network is performed exploiting a flexible Modelica framework. The case study focuses on the Italian grid with the aim of providing useful indications for optimization tasks. Through linearization and model order reduction, a simplified model of the network is obtained to evaluate the governing time constants with which pressures propagate along the network after rotational speed changes of the compression stations. Further indications are provided regarding compression stations mutual interactions. The analysis is validated considering simplified network models and specific tests on the entire network. The proposed approach can also be applied to systems of comparable size and complexity that can transport hydrogen and hydrogen mixtures.

Gas Losses in the Distribution Networks: An Interdisciplinary Analysis

This work focuses on a very important and current problem in the gas field: gas losses in natural gas distribution networks and their impact on the environment, as well as on the company operating the network. The paper starts with a bibliographic study and aims to identify the sources leading to losses, estimate loss volumes, reduce these losses by replacing high-risk pipeline sections, as well as trace the economic, environmental, and social impact. The calculation methodologies used in various countries in estimating these consumptions are very diverse. Romania uses a very dense methodology that can prompt very broad variations in the values obtained for technological consumption calculations using Order 18/2014, due to the multitude of parameters that must be estimated. To reduce some of the uncertainties in estimating these parameters, a study was proposed and carried out on the ill-fittings in the natural gas distribution systems. The article presents the experimental stand, the analysis of the experimental data, the methodology for calculating gas losses in the natural gas distribution system through leaking equipment, as well as the results obtained and the conclusions. Moreover, an application was made for a dynamic area check of the gas balance. Based on the correlations between the annual values in M&R stations, AMR, the volume for small consumers, technological consumption, linepack, and the equipment and materials used in the network, useful data were obtained in the diagnosis of problem areas. The end of the paper shows an economic calculation regarding the replacement of problematic pipeline sections in natural gas distribution networks. The difference between the volume of investments and the income from loss reduction is very large, but the aspect of protecting the environment and eliminating technological risks intervenes, thus increasing social security and health.

Effects of the legacy pipe ends on the behaviour of pipe-in-pipe repair systems under internal pressure

Pipe-in-pipe (PIP) has become an acceptable system for the rehabilitation and repair of natural gas distribution networks. Damaged host pipes usually contain defects such as circumferential cracks which can affect the performance of the PIP systems. Under internal pressure, the PIP system will be in contact with the damaged pipes and may have an adverse effect on its structural performance. This paper investigates the effect of the sharp edge of the legacy pipe opening on the PIP systems under the internal pressure. The effect of several design parameters including the bonding condition of the PIP to the host pipe, the material properties of the PIP system, and the level of sharpness of the host pipe ends are evaluated. The numerical results show that without bonding of the PIP to the host pipe, the stress concentration is minimised as the PIP can deform around the edge of the host pipe. The use of high strain PIP material systems and rounding the edge of the host pipe also contribute to reducing stress concentration. The irregular opening of the legacy pipe represents the practical situation in which both unbonded and rounded factors are found effective in terms of stress concentration relief. The outcomes of this work provide useful information on minimising stress concentrations on PIP systems, which can be effectively utilised in repairing damaged pipes with a circumferential crack under the internal pressure loading.

Integrated Operation of Electricity and Natural Gas Distribution Networks: A Reliability Analysis

Currently the world faces a great challenge, to achieve a sustainable production of energy, which allows the adequate development of humanity but at the same time does not irreversibly affect the environment. For this, it is absolutely necessary to make optimal and effective use of the available energy resources, in order to aim for energy transition objectives that result in the rational and efficient use of energy, the penetration of renewable resources, and social development. This requires that at a technical level, methodologies be proposed that allow for a holistic analysis of the different interactions and synergies present in the energy system. Therefore, it is essential to delve into the knowledge associated with the interaction between the electricity and natural gas networks, since natural gas is expected to be the energy source that supports the increase in generation from intermittent renewable energy sources. It is for the above that this research work analyzes the reliability of the electric power distribution network based on the impact associated with a contingency in the natural gas distribution network, when both networks are coupled through natural gas-based distributed power generators. A novel non-supplied energy index and a single contingency criterion are used for estimation purposes, considering failure rates and repair times of the natural gas network to obtain a more accurate in the estimation. Numerical results show that significant penetration of natural gas-based distributed generation can compromise the reliability of the power distribution network if the natural gas network is of low reliability.

Network analysis for optimal biomethane plant location through a multidisciplinary approach

Bioenergy production from agricultural biomass is considered a key opportunity for achieving the sustainable development goals set by various international institutions. This sector must combine efficiency and profitability with environmental protection and territorial integration. For this reason, plants location should consider the natural and anthropic characteristics of the areas where they are supposed to operate. In this paper, a multicriteria analysis is introduced for optimal location of biomass plants in a region of Northern Italy. The study was based on a detailed set of 8 constraints and 15 criteria, and eventually identified 93 potential sites for plant location. The distribution of biomass from the territory to the plants was carried out with the specific Location-Allocation algorithm that allowed considering both the attractiveness of the plants and the maximum acceptable power. This result was compared with the current bioenergy production system: three alternative scenarios were developed, considering existing plants and the natural gas distribution network. Finally, a sensitivity analysis was conducted, to study the consequences of various decision-makers decisions. The results showed the possibility of installing between 90 and 199 plants in the different scenarios, resulting in a biomethane production between 246.8·106 Nm3 and 503.6·106 Nm3.

Properties and Analysis of Gaseous Alternative Fuels II: Fuels Based on Natural Gas and Biogas

The importance of alternative energy sources is constantly growing, especially due to the ever-increasing energy consumption of mankind and due to the effort to replace existing sources with more environmentally friendly ones. This article is another in a series of articles focused on an overview of technical requirements and testing methods for alternative gaseous, liquid, and solid fuels. This series of articles aims to provide an overview of the required properties of individual alternative fuels, the possibilities of their analysis, and the significance of individual analyzes. This article provides an overview of the technical requirements prescribed by legislation and relevant standards for automotive fuels based on natural gas (fossil methane) and biomethane. Furthermore, prescribed analytical tests are presented, which have been used to monitor the quality of these fuels. To a lesser extent, the importance of selected analytical tests is also discussed. Natural gas can be compressed or liquefied for use in automobile transport. In the first case, CNG fuel is obtained, and in the second, LNG. As a source of renewable methane or biomethane, biogas can be used, which is produced by anaerobic fermentation of agricultural waste or other raw materials in biogas plants. The obtained biogas can be used for the combined production of heat and energy. Alternatively, it can be purified into biomethane, which can be injected into the natural gas distribution network or used in automobile transport in the form of bio-CNG and bio-LNG. In general, it can be stated that the analysis of fuels based on natural gas and biomethane is well managed. Instrumental equipment and analytical methods used for natural gas analysis can be used to analyze these fuels. The properties of fuels based on natural gas and biomethane are closely related to their composition. In terms of proper operation and performance of the combustion engine, the lower heating value, Wobbe number, and methane number are critical parameters. An important parameter is also the sulfane content, increased content of which can lead to corrosion of engine components. In terms of emissions, the total sulfur content is an important parameter also. Sulfur compounds are undesirable in emissions for environmental reasons. At the same time, they are also catalytic poisons. Other critical parameters of fuels based on natural gas and bio-methane are the water content or dew point of water.

Probabilistic framework to quantify the seismic resilience of natural gas distribution networks

Natural Gas Distribution Networks (NGDNs) are complex infrastructure systems that play an essential role in ensuring the welfare and prosperity of many communities by serving their residential, commercial, industrial, and transportation sectors. Earthquakes can damage the critical components of NGDNs and disrupt their services. The disruption of NGDN services can lead to significant economic and social losses. These losses can be mitigated by adopting appropriate resilience enhancement measures. This study puts forward a probabilistic framework to quantify the seismic resilience of NGDNs. This framework comprises multiple interconnected probabilistic models that work in harmony to characterize the earthquake-induced damage to NGDN components, their post-earthquake recovery process, and the losses incurred by the community due to the disruption in the natural gas flow. It considers various uncertainties, including those associated with the earthquake location, time and intensity, the response of various NGDN components and the earthquake-induced damage they may sustain, the duration and cost of the recovery process, and the demand for natural gas during the recovery process. To appropriately model the complex behavior of the NGDNs, their dependency on power networks is also considered. A novel index for quantifying the resilience of infrastructure systems is also introduced that considers the recovery duration in addition to the losses incurred by the community. To showcase the capabilities of the proposed framework, it is used to evaluate the seismic resilience of the natural gas distribution network of a virtual community. This framework can be used to evaluate and compare various resilience enhancement strategies.

Coordinated Planning of Electric Power and Natural Gas Distribution Systems With Refueling Stations for Alternative Fuel Vehicles in Transportation System

The alternative fuel vehicles (AFVs) which include electric vehicles (EVs) and natural gas vehicles (GVs) have gained much attention in recent years for delivering a clean and low-carbon urban mobility. The AFV development is promoting the coordination among electric power, natural gas, and transportation (ENT) networks. This paper proposes a coordinated planning method for investment on and operation of emerging urban energy infrastructures. The sites and sizes of refueling stations are optimized along with the expansion strategies for electric power distribution network (PDN) and natural gas distribution network (GDN). First, AFV refueling demands are analyzed according to the refueling station constraints and options, and transportation network (TN) constraints. Second, the coordinated planning model for PDN and GDN is formulated along with respective operation constraints in PDN, GDN, and TN. An efficient MILP solution method is developed for the proposed optimization problem. Finally, several case studies verify the effectiveness of the proposed model and its solution method. Compared with existing solutions, the proposed panning method offers a more accurate AFV refueling demand model with various refueling options. It is demonstrated that the coordinated planning can reduce investment and operation costs of urban energy infrastructures by exploring the pertinent interactions among constrained PDN, GDN, and TN.