Natural Gas Distribution Research Articles

Development of Company-Specific Emission Factors with Confidence Intervals for Natural Gas Customer Meters in Southern California.

Methane is both a significant and short-lived greenhouse gas compared to CO2, and reducing methane emissions from natural gas distribution systems may offer cost-effective reduction opportunities. We report substantial new direct leak rate measurements from customer meter set assemblies (MSAs) in Southern California. In a novel way, emission factors are defined in terms of aboveground Hazardous and Nonhazardous leak categories, which take direct advantage of readily available industry leak data. We also studied leaks that were not detected as part of normal leak survey procedures. As a result, this yields company-specific emission factors that can be used to track progress in reducing methane emissions. This approach also has the advantage of explicitly accounting for the skewed or fat-tail distribution of leak rates by treating high flow rate MSA leaks separately from low flow rate MSA leaks. The Southern California Gas (SoCalGas) methane emission factors, based on 485 leak rate measurements by direct enclosure, were 4.55 (95% confidence interval: 2.32 to 7.14) kg/day for Hazardous leaks, 0.149 (0.119 to 0.183) kg/day for Nonhazardous leaks, and 0.0039 (0.0003 to 0.0198) kg/day for Non-Detected leaks. The percentage of surveyed meters with nondetected leaks was 29.1% (24.3 to 34.6%). Based on a robust Monte Carlo analysis, total leak emissions from MSAs for the SoCalGas system were reduced by 35% based on data from 2015 to 2022. These reductions were attributed to surveying a larger number of MSAs and accelerated leak repair rates. In traditional population-based emission inventories, an individual emission factor for a given asset category is multiplied by the total population of MSAs within the category. This approach simply cannot capture the reduction in leak numbers and methane emissions resulting from leak mitigation and prevention programs.

Compatibility study of high density polyethylene grade 80 gas pipe with synthetic polyglycol-based brake oil

High Density Polyethylene (HDPE) is one attractive technical option for the transportation and distribution of natural gas and hydrocarbons given the advantages in long-term mechanical strength, lifespan, maintenance costs and resistance to chemical aging. This study investigates the compatibility of extruded pipe material from copolymerized HDPE-80 with DOT 3 brake fluid. Machined standard specimens from inner (IL) and outer (OL) pipe layers are aged in commercial synthetic polyglycol-based oil for 7 days at laboratory conditions. The percent mass changes are +2.2% and +1.9% respectively for IL and OL pipe surfaces. These results are in the same range of published sorption data for other oils and fuels. Stress-strain parameters (E, σ y, σ CD, σ f, ε y, Δ ε CD, ε f) and fracture work are established and thoroughly discussed for both pipe sides. For IL, the reduction of E, σ y and ε f are respectively 28.0%, 13.9% and 22.7%, while for OL they are 22.6%, 7.7% and 25.1%. Globally, it is concluded that strength properties degradation in DOT 3 oil is more important for IL compared to OL. There is an important loss of ductility for both pipe sides. Ageing caused IL crystallinity ( Xc) to increase while OL showed inverse results probably because of frozen anti-oxidants in the outer surface layers following water quenching during extrusion. Before and after ageing, the as-received OL is found to be more resilient to oxidation than corresponding IL, as higher OIT parameters are also shown in the case of crude oil compatibility investigations. DOT 3 brake oil seem to accelerate the degradation of HDPE-80 thermal stability with a higher intensity for IL.

First validation of high-resolution satellite-derived methane emissions from an active gas leak in the UK

Abstract. Atmospheric methane (CH4) is the second-most-important anthropogenic greenhouse gas and has a 20-year global warming potential 82 times greater than carbon dioxide (CO2). Anthropogenic sources account for ∼ 60 % of global CH4 emissions, of which 20 % come from oil and gas exploration, production and distribution. High-resolution satellite-based imaging spectrometers are becoming important tools for detecting and monitoring CH4 point source emissions, aiding mitigation. However, validation of these satellite measurements, such as those from the commercial GHGSat satellite constellation, has so far not been documented for active leaks. Here we present the monitoring and quantification, by GHGSat's satellites, of the CH4 emissions from an active gas leak from a downstream natural gas distribution pipeline near Cheltenham, UK, in the spring and summer of 2023 and provide the first validation of the satellite-derived emission estimates using surface-based mobile greenhouse gas surveys. We also use a Lagrangian transport model, the UK Met Office's Numerical Atmospheric-dispersion Modelling Environment (NAME), to estimate the flux from both satellite- and ground-based observation methods and assess the leak's contribution to observed concentrations at a local tall tower site (30 km away). We find GHGSat's emission estimates to be in broad agreement with those made from the in situ measurements. During the study period (March–June 2023) GHGSat's emission estimates are 236–1357 kg CH4 h−1, whereas the mobile surface measurements are 634–846 kg CH4 h−1. The large variability is likely down to variations in flow through the pipe and engineering works across the 11-week period. Modelled flux estimates in NAME are 181–1243 kg CH4 h−1, which are lower than the satellite- and mobile-survey-derived fluxes but are within the uncertainty. After detecting the leak in March 2023, the local utility company was contacted, and the leak was fixed by mid-June 2023. Our results demonstrate that GHGSat's observations can produce flux estimates that broadly agree with surface-based mobile measurements. Validating the accuracy of the information provided by targeted, high-resolution satellite monitoring shows how it can play an important role in identifying emission sources, including unplanned fugitive releases that are inherently challenging to identify, track, and estimate their impact and duration. Rapid, widespread access to such data to inform local action to address fugitive emission sources across the oil and gas supply chain could play a significant role in reducing anthropogenic contributions to climate change.

Iterative convex relaxation of unbalanced power distribution system integrated multi-energy systems

This study describes a multi-period, multi-energy operation of a three-phase unbalanced Electric Distribution System (EDS) that coordinates with a District Heating System (DHS) and a Natural Gas (NG) distribution system. The electrical subsystem problem is formulated as a bi-level programming problem, with levels 1 and 2 solving the subsystem’s linearized and relaxed nonlinear versions, respectively. Second-Order Cone Programming (SOCP) and polyhedral relaxations are availed to circumvent the non-convexities involved in the subsystems. The SOCP relaxation for an unbalanced power distribution network is inexact; also, the subsystems applying polyhedral relaxation may not generate a meaningful solution as the relaxations are not tight. Therefore, a solution recovery algorithm is developed for each subsystem to recover a feasible solution from their relaxed counterparts. The successive bound tightening algorithm employing a solution recovery procedure is proposed for each subsystem, improving solution quality and strengthening the relaxations with the desired computational efficiency. The proposed solution strategy to optimize the Multi-Energy System (MES) operation cost is verified on the three-phase IEEE-13 and IEEE-123 bus systems, each coordinating with a 30-node DHS and a 6-bus NG network. The results analyses demonstrate that the proposed solution strategy efficiently achieves an optimal solution, reducing maximum relaxation error below 0.1% for each subsystem. The proposed strategy delivered a 14.58% reduction in real power losses and a 12.73% decrease in phase voltage unbalance rate for the EDS in MES. Furthermore, a 1.96% decrease in operational cost demonstrates the techno-economic benefits of the proposed strategy.

GIS-BASED REAL-TIME GAS LEAK DETECTION SYSTEM AT BASKENT NATURAL GAS DISTRIBUTION COMPANY

Abstract. Natural gas has been used for heating and production purposes in Turkey since 1987, and every passing year, the natural gas pipeline network continues to expand with investments. The distribution of natural gas within urban areas is achieved through a complex network structure formed by the joining of Polyethylene (PE) and Steel (ST) pipes using various connection elements. This complex structure is susceptible to deformation over time due to various reasons such as corrosion in steel lines, manufacturing errors in connection elements in PE lines, and other factors. As a result, natural gas leaks occasionally occur in these pipelines. The leakage control process in natural gas pipelines is carried out using specially designed equipment and vehicles equipped for this purpose. However, while these systems may be sufficient for collecting the necessary data for leak detection, the complex structure of the distribution network and the necessary data for leak detection, the complex structure of the distribution network and the necessity of performing this process with multiple teams bring about many challenges in terms of tracking, management, and reliability of the operation. At this point, the advancement of GIS (Geographic Information System), mobile, and communication technologies has made it possible to overcome these challenges. In this study, a real-time GIS-supported leak detection system developed using these technologies for Başkent Natural Gas Distrubition Inc. (Başkentgaz), which provides natural gas distribution services in Ankara, has been described. The study discusses the benefits brought by this system to the natural gas leak detection process.

A Multi-Agent Distributed Operation Solution to Electricity and Natural Gas Distribution Systems for Enhancing Resilience

A Multi-Agent Distributed Operation Solution to Electricity and Natural Gas Distribution Systems for Enhancing Resilience

Sealing capacity evaluation of underground gas storage under intricate geological conditions

Evaluating underground gas storage (UGS) sealing capacity is essential for its safe construction and operational efficiency. This involves evaluating both the static sealing capacity of traps during hydrocarbon accumulation and the dynamic sealing capacity of UGS under intensive gas injection and withdrawal, and alternating loads. This study detailed the methodology developed by Sinopec. The approach merges disciplines like geology, geomechanics, and hydrodynamics, employing both dynamic-static and qualitative-quantitative analyses. Sinopec's evaluation methods, grounded in the in situ stress analysis, include mechanistic studies, laboratory tests, geological surveys, stress analysis, and fluid-solid interactions. Through tests on the static and dynamic sealing capacity of UGS, alongside investigations into sealing mechanisms and the geological and geomechanical properties of cap rocks and faults, A geomechanics - rock damage - seepage mechanics dynamic coupling analysis method has been developed to predict in situ stress variations relative to pore pressure changes during UGS operations and evaluate fault sealing capacity and cap rock integrity, thereby setting the maximum operational pressures. Utilizing this evaluation technique, Sinopec has defined performance metrics and criteria for evaluating the sealing capacity of depleted gas reservoirs, enabling preliminary sealing capacity evaluations at UGS sites. These evaluations have significantly informed the design of UGS construction schemes and the evaluation of fault sealing capacity and cap rock integrity during UGS operations.

Damage to Natural Gas Distribution Steel Pipelines caused by Rigid Bodies resulting from the Excavation of Laying Trenches

The present paper focuses on analyzing the occurrence of defects such as dents and local deformations by laboratory simulations of a real case of a defect detected on a natural gas distribution pipeline lain at a depth of approximately 0.6 m. The defect is caused by a river stone which due to the compression forces, damages the pipe to the point of cracking. In the laboratory, the simulation was carried out on a steel pipe insulated with extruded polyethylene which was acted upon by a mandrel made of duralumin. The purpose of the tests is to determine the maximum values at which the pipe material fractures. It was found that the fracture of the pipes when there are rigid bodies in the protective layer of sand is accelerated by the sand existing between them and the pipe and by the change in the properties of the steel the pipes are made of when they are kept in water.

A Resonator Noise Reduction Solution for a Centrifugal Gas Compressor

The purpose of this work is to reduce the noise generated by a compressor that conveys methane gas. After certain measurements were conducted a high level of noise was observed in the 2000-3000 Hz range, therefore a solution for noise reduction at the source is addressed and presented in this paper. The research method is based on designing resonators to be applied on the stator of a centrifugal compressor used in a natural gas distribution station. First, the calculations are made on resonators with air as the working fluid and then are validated through real measurements in a Kundt tube. After validation, the working fluid is changed with gas, calculations are made once again, and acoustic simulations are performed. To facilitate acoustic simulations and reduce computational time, a simplified stator geometry was employed. This simplified model encompassed the region starting from the rotor's gas exit, where the resonators were deployed. The purpose of the acoustic simulation was to validate the frequency range influenced by the resonators and to estimate the overall noise reduction. Depending on the operating regime of the compressor, the rotor fundamental can vary within the frequency domain of 2000 – 3000 Hz. This broadband domain requires the usage of several resonators with different resonant frequencies. The proposed solution obtained an average value of attenuation, excluding the peaks of the attenuation, in the frequency domain of 2000 - 3000 Hz, of 9 dBA. If the fundamental frequency coincides with a resonance of the resonator, higher attenuation can occur. Also, fundamental attenuation can lead to attenuation of the harmonics.

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.

Design of Unplasticized Polyamide 12 Oilfield Line Pipe Based on Published Regression Curves and ASTM F3524

The long-term strength of unplasticized polyamide 12 (PA-U12) has been characterized using standard methods for plastic pressure pipe during the qualification process for use in buried piping systems for natural gas delivery operating at low ambient temperatures, usually less than 20 to 30°C at pressures previously served only by steel pipe. The high strength characteristics of the material also made it interesting as a steel substitute for buried and above-ground industrial pressure pipe applications. So far, typical geometries are diameters up to 6 inch (162 mm) with wall thicknesses up to DR9. Assuming a design factor of 0.63 applied to the PPI TR-4 listed HDB, DR9 PA-U12 pipes have a maximum pressure at 23°C of 496 psig (3.4 MPa), although design pressures will typically be lower. These industrial systems can operate at much higher temperatures, up to ~ 50°C for above-ground installations in pipe supports or up to ~ 65°C for surface-laid oilfield pipes. Design engineers need the temperature dependent strength curves to properly design a thermoplastic pressure piping system. Therefore, the regression curves have been extended by LTHS tests up to 120°C. Corresponding test durations enabled to define the location of knees with determination of second branches. These branches are caused by hydrolytic degradation of the polymer resulting in brittleness of the polyamide after long times at elevated temperature in sufficiently wet environments or services. The first appearance of a knee is at 60° C and approximately 44 years. This paper describes various standards to which PA-U line pipe and materials must conform, and the development of standardized, temperature dependent, long-term strength reference curves for PA-U12 pressure pipe, including the transition from ductile to brittle behavior at long times and high temperatures. These curves have been standardized first in DVS and followed by ISO based on the combined LTHS data of pipes made from two different PA-U12 180 compounds and one PA-U11 180 compound. An example of a typical PA-U12 180 pipe design is presented, applying chemical resistance derating factors for oil and gas applications in the design process. Short Summary: Oilfield pipeline design engineers need temperature dependent strength curves to properly design a thermoplastic pressure piping system for use at temperatures often far above the typical range for natural gas distribution. Therefore, LTHS regression curves have been experimentally developed at temperatures up to 120°C to define the location of knees and characterization of second branches. In this paper we describe various standards to which PA-U line pipe and materials must conform, and the development of standardized, temperature dependent, long-term strength reference curves for PA-U12 pressure pipe, including the transition from ductile to brittle behavior at long times and high temperatures. These curves have been standardized in ISO and DVS and apply to both PA-U12 and PA-U11 [1,2]. For PA-U12 line pipe we also present an example for a typical pipe design, where chemical resistance derating factors are applied for oil and gas applications in the design process.

Electrolysis-boosted substitute natural gas from biomass: Kinetic modeling of fluidized bed gasification and system integration

The present work deals with the modeling of electrolysis-boosted biomass gasification for the production of green synthetic methane (or substitute natural gas) with a composition that enables its potential injection into the natural gas distribution grid.A kinetic and hydrodynamic model has been built to simulate a bubbling fluidized bed reactor using a mixture of steam and oxygen as gasifying agent. The model was firstly validated by comparing it with experimental results available in the open literature. Outlet temperature spans from about 730 to 1060 °C depending on the used amount of oxygen and steam within the gasifying agent, expressed through parameters like equivalence ratio and steam-to-biomass ratio.Then, process modeling for the integration between biomass gasification and high-temperature steam electrolysis has been carried out. Electrolysis has been sized to enrich the hydrogen content of the syngas, enabling a stoichiometric composition in terms of hydrogen, carbon monoxide, and carbon dioxide for the subsequent catalytic methane synthesis via carbon oxides hydrogenation. Thermal integration has been carefully designed to improve the overall process efficiency up to about 71 % (based on lower heating value of both biomass and substitute natural gas).

Comparative Study of Mathematical Models for Describing the Distribution of Hydrogen-Enriched Natural Gas in Enclosed Spaces

Comparative Study of Mathematical Models for Describing the Distribution of Hydrogen-Enriched Natural Gas in Enclosed Spaces

Ground-Based Mobile Measurements to Track Urban Methane Emissions from Natural Gas in 12 Cities across Eight Countries.

To mitigate methane emission from urban natural gas distribution systems, it is crucial to understand local leak rates and occurrence rates. To explore urban methane emissions in cities outside the U.S., where significant emissions were found previously, mobile measurements were performed in 12 cities across eight countries. The surveyed cities range from medium size, like Groningen, NL, to large size, like Toronto, CA, and London, UK. Furthermore, this survey spanned across European regions from Barcelona, ES, to Bucharest, RO. The joint analysis of all data allows us to focus on general emission behavior for cities with different infrastructure and environmental conditions. We find that all cities have a spectrum of small, medium, and large methane sources in their domain. The emission rates found follow a heavy-tailed distribution, and the top 10% of emitters account for 60-80% of total emissions, which implies that strategic repair planning could help reduce emissions quickly. Furthermore, we compare our findings with inventory estimates for urban natural gas-related methane emissions from this sector in Europe. While cities with larger reported emissions were found to generally also have larger observed emissions, we find clear discrepancies between observation-based and inventory-based emission estimates for our 12 cities.

Joint Management and Optimization of Residential Natural Gas and Electricity Distribution Networks Coupled via Fuel Cells

Joint Management and Optimization of Residential Natural Gas and Electricity Distribution Networks Coupled via Fuel Cells

The hydrogen perspective for Türkiye, which is on the Asia-Europe energy transition route. Can Türkiye become hydrogen hub?

This study examines the potential for hydrogen to undertake a leading role in the transition to sustainable energy in Türkiye. Türkiye, with its well-established energy infrastructure and increasing focus on renewable energy, has the potential to undertake a significant part in the worldwide hydrogen market. The research uses a multi-level perspective to analyse the interactions between different region connected with Türkiye, and the processes and strategies within the national energy system. The findings suggest that hydrogen production and transport in Türkiye has the potential to significantly contribute to the decarbonization of the industry and flexibility services in Asia, Europe and Africa. However, the ongoing advancement in the field of hydrogen in Türkiye is at a critical juncture where coordinated efforts are necessary to fully realize its potential. Türkiye recently announced the Hydrogen Technologies Strategy and Roadmap. Under the new Hydrogen Technologies Strategy and Roadmap, Türkiye plans to significantly increase the production of hydrogen. Türkiye plans to significantly increase its installed electrolyser capacity to support the production of hydrogen. Specifically, the plan aims to increase the installed capacity to 2 GW by 2030, 5 GW by 2035, and 70 GW by 2050. Turkey's strategic investments and policy adjustments could propel its green hydrogen production to 3.4 million tons yearly by 2050. With an anticipated domestic demand for hydrogen at 1.9 million tons annually, Turkey could potentially export between 1.5 and 1.9 million tons yearly by 2050. Türkiye boasts an extensive network of transmission and distribution pipelines for natural gas, totalling 10,000 km, including those with large diameters. The existing pipelines could transport hydrogen in its pure form or blended with natural gas. The natural gas pipeline capacity in Turkey stands at 32 billion cubic meters. This infrastructure enables the transportation of an estimated 575 million tons of hydrogen yearly to neighboring countries by employing a mix of 20 % hydrogen and natural gas. With an extensive network of natural gas transmission and distribution pipelines, Turkey positions itself as an integral part of the interconnected hydrogen energy infrastructure, linking the nation with Europe and neighboring regions. The results of this study present new approaches into the dynamics of the energy system and contribute to ongoing discussions about transition routes and consider the current status of hydrogen in Türkiye, the country's renewable energy potential, the policy and regulatory framework, and the infrastructure and market conditions necessary in order to foster the growth of a hydrogen hub.

Social and economic risk analysis of natural gas distribution networks

Social and economic risk analysis of natural gas distribution networks

Effectiveness of Water-Amine Combined Process for CO2 Extraction from Biogas

Abstract The EU countries are implementing biomethane production projects from biogas, supplying it to the natural gas distribution grid, or using it as motor fuel. It is also extremely relevant for Ukraine, supposing the problems with gas import due to Russian aggression. Biogas production from landfills, agriculture waste, and sewage is already implemented in Ukraine, so the next step must be biomethane production on an industrial scale and the selection of biogas separation technology is important. Using 11 years of industrial experience in biogas production from landfills, wide experience of the different methane-containing gases separations, and small companies’ industrial possibilities, the most applicable separation technologies for Ukraine were selected: amine, water, and combined water amine carbon dioxide separation. These technologies had compared using computer simulation with real landfill biogas flow rate debt. Results of a software simulation of the most applicable water-amine absorption technology were verified using a laboratory setup. For carbon dioxide concentration in biogas at 32–42 % vol., the specific energy consumption when using water absorption is on average 2 times less compared to amine absorption, but at the same time, the loss of methane due to its solubility in water during water absorption amounted to 7.1–7.6 %, with practically no losses in amine absorption, and minor losses at 0.17–2.8 % in combined water-amine technology. The energy consumption of combined water-amine absorption is comparable to that of water absorption due to: a) reduction of heat losses for the regeneration process of saturated amine absorbent, as part of carbon dioxide has already been removed with water technology; b) using the methane excess to compensate power consumption of the biogas compressor during the preliminary water absorption of carbon dioxide and/or to compensate heat costs of the saturated amine absorbent regeneration

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.