Natural Gas Pipeline Network Research Articles

Assessment method for gas supply reliability of natural gas pipeline networks considering failure and repair

Pipeline networks are the primary means of natural gas transmission, and assessing the gas supply reliability is of great significance for the safe and stable operation of pipeline networks. However, current assessment researches for the gas supply reliability are just conducted on the entire pipeline networks and based on the failed pipeline networks, i.e. the assessment process is static. The individual difference differences among users and the reparability of pipeline networks are neglected, which make the assessment results not comprehensive and objective enough. To address these problems, a new assessment index is defined to assess the gas supply reliability of individual users by combining the gas shortage time and severity in this paper, and the gas supply reliability assessment is carried out from the perspectives of entire pipeline networks, individual users, gas shortage amount and gas shortage time. Furthermore, an operation state determination model of pipeline networks is established based on the failure and repair processes. Finally, a systematic assessment method with dynamic characteristics is proposed. By using the assessment method, the gas supply reliability of an actual pipeline network is assessed. The differences between the assessment of entire pipeline network and individual users are compared, and the importance ranking of components is presented. The assessment results can provide a theoretical basis for an economical optimization of the gas supply reliability of pipeline networks.

Study on the multi-objective optimization of reliability and operating cost for natural gas pipeline network

The development of natural gas pipeline network towards larger scale and throughput has urged better reliability of the pipeline network to satisfy transportation requirement. Previously, studies of optimizing natural gas pipeline network have been mainly focused on reducing operating cost, with little concern on the reliability of pipeline network. For a natural gas pipeline network with a variety of components and complicated topology, a multi-objective optimization model of both reliability and operating cost is proposed in this study. Failure of each component and the state of pipeline network under failure conditions are taken into account, and minimum cut set method is employed to calculate the reliability of the pipeline network. The variables to be determined for the optimization objectives are the rotating speed of compressors and the opening of valves. Then the solving procedure of the proposed model is presented based on Decoupled Implicit Method for Efficient Network Simulation (DIMENS) method and NS-saDE algorithm. The validity of the optimization model is ascertained by its application on a complicated pipeline network. The results illustrate that the optimization model can depict the relative relationship between reliability and operating cost for different throughput, by which the operation scheme with both satisfying reliability and operating cost can be obtained. In addition, the customer reliability and the impact of the failure of each pipeline on the whole network can be evaluated quantitatively to identify the consumers and pipelines of maintenance priority. The pipeline network reliability can be improved through proper monitoring and maintenance of these consumers and pipelines.

Effects of hydrogen blending on hydraulic and thermal characteristics of natural gas pipeline and pipe network

Blending a fraction of hydrogen into the natural gas pipeline or urban pipe network is an efficient approach for hydrogen delivery. In this paper, the mathematical model of Hydrogen-Blended Natural Gas (HBNG) transportation is established, and the influences of hydrogen blending on hydraulic and thermal characteristics of natural gas pipeline and pipe network are numerically investigated. The impact of hydrogen blending ratio on the performance of centrifugal compressor and the operating point for joint operation of pipeline and compressor is discussed. Results illustrate that compared with natural gas without hydrogen, the hydrogen blending can reduce the pipeline friction resistance and increase the volume flow rate. However, due to the lower volumetric calorific value of HBNG, the energy flow rate actually decreases under the same transportation condition. Meanwhile, the temperature drop along the pipeline slows down due to the blended hydrogen. The performance degradation of centrifugal compressor occurs with the increasing hydrogen blending ratio, and the operating point for joint operation of pipeline and centrifugal compressor moves to the direction of higher volume flow rate and lower pressure. This study is expected to shed a light on the hydrogen delivery by natural gas pipelines and pipe networks.

Analysis of Driving Factors of Natural Gas Consumption in China: Based on Regional Integration and LMDI Method

In recent years, China has developed rapidly in terms of natural gas. Driven by regional economic integration, a regional natural gas market composed of neighboring provinces and cities has taken shape gradually, and it tends to grow toward the same direction in policy formulation, resource coordination, facility construction and market expansion. Based on the factors such as geographical location, economic conditions and natural gas consumption, this thesis tends to conduct a horizontal comparative analysis on the economic development conditions, natural gas consumption characteristics and natural gas pipeline network density of the three regions with obvious regional integration feature in China. Then according to LMDI, four core indicators, namely economic growth effect, energy intensity effect, energy structure effect, and substitution effect are selected. The thesis is expected to explore the contribution of different indicators to the growth of natural gas consumption in these three different regions. According to the results, it can be concluded that the driving factors of natural gas consumption differ greatly among regions. Specifically speaking, the more developed the economy is, the greater the contribution of the energy substitution effect to natural gas consumption will be, and the contribution of the economic growth effect to natural gas consumption will be smaller. Despite that the contribution of energy intensity in different regions shows slight difference, the energy structure contributes the least effect, which further explains the current differences in China’s natural gas consumption characteristics and the reasons behind.

Dynamic linepack depletion models for natural gas pipeline networks

Given the critical role played by natural gas in providing electricity, heat, and other essential services, better models are needed to understand the dynamics of natural gas networks during extreme events. This paper aims at establishing appropriate and fast simulation models to capture the slow dynamics of linepack depletion for ideal isothermal natural gas pipeline networks. Instead of solving partial differential equations (PDE) on a large scale, three alternative implicit ordinary differential equation (ODE) simulation techniques are derived and discussed. The first one is commonly used in the literature with a slack node assumption. We show that the system of equations associated with this model is degenerate when flux injections are controlled (i.e. specified) at all nodes. To recover regularity under such a condition, two novel implicit ODE models are proposed with different techniques on boundary conditions. They are easy to derive and efficient to simulate by standard ODE solvers. More importantly, they present useful frameworks for analyzing how networks respond to system-wide mass flux imbalances. These techniques offer different alternatives for simulating system dynamics based on how sources and loads are chosen to be modeled, and they are all proven to be regular (non-degenerate) in tree-structured networks. These proposed techniques are all tested on the 20-node Belgium network. The simulation results show that the conventional model with the slack node assumption cannot effectively capture linepack depletion under long term system-wide mass flux imbalance, while the proposed models can characterize the network behavior until the linepack is completely depleted.

Power-to-Gas, Hydrogen, and a Spotlight on New York's Emerging Climate and Energy Policy

This paper examines the role of law and regulation in advancing technology-based energy decarbonization options such as hydrogen compatible networks and power-to-gas (P2G) in the context of New York’s energy and climate change mitigation goals. By exemplifying the potential of P2G and hydrogen, it underscores the need for a more comprehensive legal and regulatory framework that (i) reflects the peculiarities of gas and electricity systems (on the one hand) and (ii) facilitates a more effective and integrated energy decarbonization pathway (on the other hand). Hydrogen is an energy carrier with a significant potential to deliver zero and low-carbon energy depending on how it is produced. Also, when combined with oxygen in a fuel cell, hydrogen produces heat and electricity with only water vapor as a by-product. It has been used for several years in bespoke applications in the aeronautics, industrial, and transportation sectors. About ten million metric tons of hydrogen is currently produced in the US every year, and ninety-five percent of which is via centralized reforming of natural gas (i.e. steam methane reformation (SMR) and known as “Blue Hydrogen”) used mostly in petroleum refining and ammonia industries. Other modes of utilization include fuel cell vehicles, metals refining, and synthetic natural gas production. Notably, the P2G process leads to the production of “green hydrogen” by using electricity that would otherwise be curtailed or lost, from variable renewable energy (VRE) sources such as solar and wind. Such VRE sourced energy can be used to split water into its hydrogen and oxygen components. The ‘green hydrogen’ process is becoming increasingly relevant to the issues of (i) decarbonization of gas and electricity networks; and (ii) solving the ‘curtailment’ ‘intermittency’ and ‘storage’ challenge in an energy system where renewables are gradually playing a larger role. It may also be key to facilitating the integration of a growing share of VREs in existing networks and in the same vein helping to avoid the ‘stranded assets’ dilemma faced by operators of natural gas pipeline and storage networks which can be compatible with hydrogen or synthetic methane produced as a result. Law and regulation provide a facilitative means through which relevant institutions and operators can work towards decarbonization and develop the requisite technology-based solutions while addressing the energy policy challenges created by the increasing role of VREs. Such considerations are even more relevant for a state such as New York. Even though the state’s Clean Energy Standard revised in 2019 requires 100% carbon-free electricity by 2040; in 2019, 29% of New York's in-state generation came from renewable sources. One-third of its utility-scale net generation came from in-state nuclear power plants that are scheduled to be decommissioned soon, while it was the sixth-largest natural gas consumer in the US, and three in five households used natural gas for home heating. The emerging energy decarbonization issues can be met if, among other things, law and regulation are viewed from a functional lens. In this regard, ‘regulation’ is considered as part of a legal framework that is instrumentalist in orientation with the aim of pursuing defined energy policy objectives which typically comprise of ensuring (i) secure and reliable supplies, (ii) sustainability while protecting the environment, and (iii) ensuring that costs and rates are just and reasonable both for the suppliers and consumers. The (ii) dimension is crucial in a carbon-constrained world. Thus, the paper will consider these highlighted issues and in Part II discuss the growth and challenges with VREs in the US energy mix and then highlight potential role(s) for hydrogen and P2G as an example of innovative technology-based decarbonization solution as well as a means of efficiently integrating growing VREs in electricity context with natural gas networks. Part III will examine the regulatory issues in the regulation of gas and electricity systems in a carbon-constrained world and the challenges and potential for decarbonization by deploying hydrogen and P2G. Part IV examines New York’s emerging climate and energy regulation framework and points out the possible issues with deploying P2G and hydrogen in the state. The paper concludes by highlighting that in the pathways to decarbonization the overarching objective in determining how and what to regulate should be ‘curbing greenhouse gas emissions’. It also underscores the need to develop an integrated policy and regulatory framework that can enhance the required technologies and energy systems in the path towards decarbonization.

Data-driven computation of natural gas pipeline network hydraulics

Hydraulic calculation is a major path to the management of natural gas pipeline network. However, the assumed physical parameters such as the length of the pipes are usually investigated from blueprint or factory technical tests, which may differ from actual values and cause inaccurate hydraulic calculation result. Moreover, an initialization sufficiently near the root guarantees the convergence of the Newton’s Iteration (NI) for solving the hydraulic equations. In this paper, a data-driven hydraulic calculation method is proposed, where we make two major contributions. (i) A parameter estimation method is provided for adjustment to the hyper parameters of the hydraulic calculation. (ii) An initialization method using neural network is proposed to make an estimate for the root at a first glance to ensure the convergence. The numerical results show that the proposed data-driven parameter estimation improves the hydraulic calculation accuracy and initialization method reduces the calculation time cost.

How public values theory can influence energy infrastructure planning: Exploring values articulation, time horizons, and substitutability through the Atlantic Coast pipeline

The transformation of energy infrastructure in the United States, specifically the expansion of the transportation network of natural gas pipelines, is garnering more public attention than ever before. Once built, energy infrastructure is long-lasting and exerts a strong influence on economic conditions, environmental integrity, and social behavior. Yet, clear, strategic energy plans are lacking and federal permitting focuses on economic factors. This research explores how public values theory can be operationalized to include noneconomic factors into planning for the transformation of energy infrastructure. However, there is a paucity of mechanisms to incorporate noneconomic values into decision-making processes related to energy infrastructure. Work remains to bridge theory and practice such that public values can shape planning and permitting processes. This research presents a case study on the Atlantic Coast Pipeline project, drawing upon survey data from 268 people and three workshops with 15 participants to inform the ongoing national debate on energy infrastructure. The survey analysis suggests three key determinants for pipeline infrastructure as illustrated by: i) models of scale (size and the proportional risk); ii) eminent domain (taking lands); and iii) protectionism (“Not In My BackYard,” or NIMBY). This research also showcases three alternative approaches on how to foster deliberative democratic processes with community members. This research extends the theoretical construct of public values theory by articulating mechanisms of action and assessing the efficacy of those mechanisms. Strategic planning for energy transitions and finding ways to reduce conflict may, in the long-term, minimize construction costs and address local concerns.

Security region of natural gas pipeline network system: Concept, method and application

This paper proposes the security region of natural gas pipeline network system (NGS-SR), which provides a new perspective to analyze the security of the system. Firstly, the definition of NGS-SR is proposed, that is, the closed set of all secure operating points in the state space. NGS-SR is then modeled considering variety of operation constraints, such as the hydraulic balance constraint, the node gas pressure constraint, etc. Secondly, an observation-based method is proposed to solve the security boundary of NGS-SR. Thirdly, the approaches of security assessment and preventive control based on NGS-SR are illustrated. Finally, the NGS-SR of two typical systems are observed, analyzed and compared with the existing methods of security analysis. The results show the validity and precision of the proposed model and method, as well as the advantages of NGS-SR: 1) NGS-SR can describe the secure operating range of the system in a geometric and visualized way; 2) NGS-SR is beneficial to realize online security analysis, the analysis speed is increased up to 1944 times in the cases; 3) NGS-SR can provide the security margin information for system operation.

Vulnerability analysis of a natural gas pipeline network based on network flow

A vulnerability analysis of the transportation capacity of a natural-gas pipeline network based on network flow was proposed. This analysis focused on the inherent properties instead of the environment and probabilities, which are usually considered in conventional risk assessments. The topology of the pipeline network was established in the form of a graph, and maximum-flow algorithm was applied to identify crucial pipelines that affect the transportation capacity of the natural-gas pipeline network. From the perspective of network efficiency and flow-based performance, three vulnerability indicators of the transportation capacity of the network were established. These indicators can better identify the critical pipelines, especially those with low failure probability but potential gas-transportation vulnerability. We investigated the development of a pipeline network and that of the natural-gas market at different stages to plan an optimal pipeline network route and determine the transmission capacity, in order to improve the reliability and economy of the entire pipeline network.

A Review of Technical Advances, Barriers, and Solutions in the Power to Hydrogen (P2H) Roadmap

Power to hydrogen (P2H) provides a promising solution to the geographic mismatch between sources of renewable energy and the market, due to its technological maturity, flexibility, and the availability of technical and economic data from a range of active demonstration projects. In this review, we aim to provide an overview of the status of P2H, analyze its technical barriers and solutions, and propose potential opportunities for future research and industrial demonstrations. We specifically focus on the transport of hydrogen via natural gas pipeline networks and end-user purification. Strong evidence shows that an addition of about 10% hydrogen into natural gas pipelines has negligible effects on the pipelines and utilization appliances, and may therefore extend the asset value of the pipelines after natural gas is depleted. To obtain pure hydrogen from hydrogen-enriched natural gas (HENG) mixtures, end-user separation is inevitable, and can be achieved through membranes, adsorption, and other promising separation technologies. However, novel materials with high selectivity and capacity will be the key to the development of industrial processes, and an integrated membrane-adsorption process may be considered in order to produce high-purity hydrogen from HENG. It is also worth investigating the feasibility of electrochemical separation (hydrogen pumping) at a large scale and its energy analysis. Cryogenics may only be feasible when liquefied natural gas (LNG) is one of the major products. A range of other technological and operational barriers and opportunities, such as water availability, byproduct (oxygen) utilization, and environmental impacts, are also discussed. This review will advance readers’ understanding of P2H and foster the development of the hydrogen economy.

Experimental study and life cycle assessment of CO2 methanation over biochar supported catalysts

With the existing natural gas pipeline network, methane can be easily transported and utilized. Catalytic conversion of CO2 into fuels can provide an attractive solution to convert greenhouse gas to valuable products. Thus, it is of great significance to synthesize CH4 from CO2 for the replacement of fossil fuels to relieve energy and environment issues. A novel Ni-based catalyst (Ni/Ce-ABC, where ABC referred to activated biochar) using biomass as raw materials was designed for CO2 methanation reaction in this study. The biochar modified by highly dispersed CeO2 was obtained from pyrolysis of Pinus sylvestris combined with in-situ activation with NaHCO3 and Ce doping and then was assessed as a catalyst support (Ce-ABC). A series of characterization methods were employed to study the detailed physicochemical properties of the catalyst. The Ni/Ce-ABC catalyst exhibited better activity than Ni/ABC for CO2 methanation, achieving a CO2 conversion of 88.6% at 360 °C with a CH4 selectivity of 92.3% at 1 MPa. In addition, the Ni/Ce-ABC catalyst showed fantastic activity at relatively low temperature. The highly dispersed Ce species on the biochar were found to be beneficial for the dispersion of the nickel species and enhancement of the CO2 adsorption capacity of biochar. Life cycle assessment suggested that the biochar-based catalysts were more environmentally friendly than the metal oxides catalysts. This study therefore developed an environmentally benign and catalytically efficient biochar-based catalyst to achieve the reduction and valorization of CO2.

Smart Micro-GaS: A Cognitive Micro Natural Gas Industrial Ecosystem Based on Mixed Blockchain and Edge Computing

With the increase in natural gas consumption, distributed natural gas supply and transaction have become new development goals of the industrial Internet of Things (IoT) for natural gas. However, there are obvious disadvantages of the existing natural gas pipeline network in aspects of infrastructure warning, multilevel data transmission, automatic transaction, and security. Emerging technologies, such as blockchain, edge computing, and AI have been introduced to address these shortcomings. This article proposes Smart Micro-GaS, i.e., the concept of a cognitive micro natural gas industrial ecosystem based on mixed blockchain and edge computing. Three aspects, multilevel, multiview, and multidimension, are put forward for its design and deployment. Then, based on the most important smart contract algorithm in blockchain, a mixed transaction model for natural gas is established. Finally, a case analysis is conducted on a smart natural gas testbed for data prediction and the proposed smart contract algorithm. The framework proposed in this article makes the natural gas data have multilevel liquidity and realizes diversified transactions.

Simulation of Marine Natural Gas Pipeline Network Impact on Natural Gas Market Based on Cloud Computing

Zhong, S.; Yu, W.; Guo, X., and Zhao, J., 2020. Simulation of marine natural gas pipeline network impact on natural gas market based on cloud computing. In: Yang, D.F. and Wang, H. (eds.), Recent Advances in Marine Geology and Environmental Oceanography. Journal of Coastal Research, Special Issue No. 108, pp. 22–25. Coconut Creek (Florida), ISSN 0749-0208.In the traditional analysis of marine natural gas pipeline network operation impact on natural gas markets, low discrimination is a problem. Therefore, based on a cloud computing model of the natural gas market, the impact on marine natural gas pipeline network operation is studied in this paper. The cloud computing model was used to determine the architecture of the marine natural gas pipeline network operation and the impact of the cloud computing system as compared with traditional methods. The experimental data show that the cloud computing method is 10% more effective than traditional methods.

Natural gas pipeline network expansion under load-evolution uncertainty based on multi-criteria analysis

This paper proposes a new approach to the design of natural gas network expansion under load evolution uncertainty in a time horizon. A predefined network topology is assumed with pipe diameters as the design variables. A dedicated optimization tool is developed so as to find not only an estimate of the optimal network, but also a set of local optimal ones, for a given most probable scenario. A Monte-Carlo simulation of the future load conditions is performed, evaluating each solution within a set of other possible scenarios. A dominance analysis is performed to compare the candidate solutions, considering the objectives of smaller installation cost, smaller infeasibility rate, smaller mean fault-cost and smaller sensitivity. A real case study is conducted concerning the design of a gas network by three engineers with 6 years of experience, on average, in the design office of a gas utility company; and their results are compared against the ones obtained from the proposed methodology. The results show that the proposed approach leads to networks that can be rather different from those obtained using a conventional, time consuming, design procedure, reaching more robust performances under load evolution uncertainties.

N-k interdiction modeling for natural gas networks

Although electricity transmission systems are typically very robust, the impacts that arise when they are disrupted motivate methods for analyzing outage risk. For example, N-k interdiction models were developed to characterize disruptions by identifying the sets of k power system components whose failure results in “worst case” outages. While such models have advanced considerably, they generally neglect how failures outside the power system can cause large-scale outages. Specifically, failures in natural gas pipeline networks that provide fuel for gas-fired generators can affect the function of the power grid. In this study, we extend N-k interdiction modeling to gas pipeline networks. We use recently developed convex relaxations for natural gas flow equations to yield tractable formulations for identifying sets of k components whose failure can cause curtailment of natural gas delivery. We then present a novel cutting-plane algorithm to solve these problems. Finally, we use test instances to analyze the performance of the approach in conjunction with simulations of outage effects on electrical power grids.

An adversarial model for attack vector vulnerability analysis on power and gas delivery operations

Power systems often rely on natural gas pipeline networks to supply fuel for gas-fired generation. Market inefficiencies and a lack of formal coordination between the wholesale power and gas delivery infrastructures may magnify the broader impact of a cyber-attack on a natural gas pipeline. In this study we present a model that can be used to quantify the impact of cyber-attacks on electricity and gas delivery operations. We model activation of cyber-attack vectors that attempt to gain access to pipeline gas compressor controls using a continuous-time Markov chain over a state space based on the gas operator Industrial Control System firewall zone partition. Our approach evaluates the operating states and decision-making in the networks using physically realistic and operationally representative models. We summarize these models, the sequence of analyses used to quantify the impacts of a cyber-incident, and propose a Monte Carlo simulation approach to quantify the resulting effect on the reliability of the bulk power system by the increase in operational cost. The methodology is applied to a case study of interacting power, gas, and cyber test networks.

Computational Fluid Dynamics (CFD) Transient Pressure and Temperature Simulation of a Natural Gas– Hydrogen Gas Blend Transportation Pipeline

The need for a CFD exploratory investigation into the possible effect of hydrogen injection into existing natural gas pipeline network, was the driver for this study. Recent technical feasibility reports on transporting a blend of both gases (JIR, 2019), did not mention if a study was done to rule out the possible effect of natural gas-hydrogen blend on hydrate formation in a hydrate-prone gas pipeline. A CFD model of 0.0508m and 10m length, with a mesh size of 20,000 elements was developed and simulated using ANSYS Fluent version R19.3. Hydrogen concentration by volume of 5%, 10%, 15% and 20% were simulated at velocities of 5m/s and 10m/s. The results indicated that increasing the volume concentration of hydrogen gas in the blend led to a reduction of downstream temperature. Again, the force on the inner wall decreased as the volume of hydrogen injected increased. The inference was that the reduction in temperature could lead to hydrates formation, whereas the reduction in exerted force on the pipe wall by the fluid could suggest a reduction in turbulence. However, this study was exploratory in nature and it is recommended that a detailed experimental study be carried out to clearly define the hydraulic and thermal behavior of a pipeline transporting a natural gas-hydrogen blend under various subcooling temperatures.

Leak Detection System for Long-Distance Onshore and Offshore Gas Pipeline Using Acoustic Emission Technology. A Review

Many petroleum products like oil and gas are transported from one place to another through pipelines, although they can undergo leakage due to pipeline leaks and cause risks to industries, the environment, and people. In this review work, we have presented a comprehensive overview of acoustic emission technology for gas pipeline leak detection. Essential gas leak detection system requirements, principles, terminologies, and risks due to failure of the natural gas pipeline system have been discussed while proposing a surface acoustic wave sensor with a combination of the Hilbert–Huang transforms (HHTs) as the best method for real-time leak detection system in the gas pipeline network. The variation of wave energy causes propagation of elastic waves that can be detected by sensors mounted on the pipeline. Natural gas pipeline networks require a continuous real-time monitoring system to ensure that the pipelines are delivering the products from one station to another at optimum conditions.

A systematic method for the analysis of energy supply reliability in complex Integrated Energy Systems considering uncertainties of renewable energies, demands and operations

Integrated Energy Systems (IES) become more and more important for the sustainability in energy system development and for promoting the application of clean energy technologies. System complexity and various uncertainties interaction make it difficult to maintain a reliable energy supply. In this paper, a systematic method is proposed for energy supply reliability analysis in complex Integrated Energy Systems (IES). The developed method integrates stochastic modeling, supply capacity analysis and reliability evaluation, which is able to give more comprehensive knowledge of the ability of the IES for satisfying the energy needs under different, coupled uncertainties. Firstly, stochastic models are developed for each unit in IES, including renewable energy, customer demands and components in natural gas pipeline networks and electric power grids, according to their characteristics. Then, a two-stage optimization model is developed for simulating the operation strategies of IESs, and calculating the supply capacities under randomly generated scenarios. Finally, the reliability of supply is evaluated based on the results of the random simulations. The developed method is used to analyze the supply reliability of an assumed IES, to test its effectiveness. The results show the ability to provide valuable information from multiple perspectives including system, individual customer and resource allocation, for design, extension and management of IES.