A risk analysis for gas transport network planning expansion under regulatory uncertainty in Western Europe

The natural gas industry in Western Europe went through drastic changes induced by the unbundling of the national companies, followed by the liberalization of gas trade and the regulation of gas transmission. Natural gas transmission is operated through a network of interconnected grids, and is capacity constrained. Each of the grids is locally regulated in terms of price limits on transportation services. Local tariff differences may induce unnatural gas routing within a network, creating congestion in some part of it. This phenomena is referred to as the Jepma effect. Following Jepma [2001. Gaslevering onder druk. Stichting JIN. Available at: www.jiqweb.org (52pp) (in Dutch)] this may lead to misguided investment decisions.     

A multi-objective model for optimizing hydrogen injected-high pressure natural gas pipeline networks

The paper develops a statistical model for optimizing the Hydrogen-injected Natural gas (H-NG) high-pressure pipeline network. Gas hydrodynamic principles are utilized to construct the pipeline and compressor station model. The model developed is implemented on a pipeline grid that is supposed to carry Hydrogen as an energy carrier in a natural gas-carrying pipeline. The paper aims to optimize different objectives using ant colony optimization (ACO). The first objective includes a single objective optimization problem that evaluates the maximum permissible hydrogen amounts blended with natural gas (NG) for a set of pipeline constraints. We also evaluated the variations in operational variables on injecting Hydrogen into the natural gas pipeline networks at varying fractions. The study further develops a multi-objective optimization model that includes bi-objective and tri-objective problems and is optimized using ACO. Traditional studies have focused on single-objective optimization with minimal bi-objective issues. In addition, none of the earlier research has shown the effect of introducing Hydrogen to the NG network using tri-objective function evaluations. The bi-objective and tri-objective functions help evaluate the effect of injecting Hydrogen on different operational parameters. The study further attempts to fill the gap by detailing the modelling equations implemented through a bi-objective and tri-objective function for the H-NG pipeline network and optimized through ACO. Pareto fronts that show the tradeoff between the different objectives for the multi-objective problem have been generated. The primary objective of the bi-objective and tri-objective optimization problems is maximizing hydrogen mole percent in natural gas. The other objective chosen is minimizing compressor fuel consumption and maximizing delivery pressure, throughput, and power delivered at the delivery station. The findings will serve as a roadmap for pipeline operators interested in repurposing natural gas pipeline networks to transport hydrogen and natural gas blend (H-NG) and seeking to reduce carbon intensity per unit of energy-delivered fuel.     

A distribution planning model for natural gas supply chain: A case study

In this paper, a real-world case study of a natural gas supply chain is investigated. By using concepts related to natural gas industry and the relations among the components of transmission and distribution network, a six-level supply chain has been introduced and presented schematically. The defined supply chain is a single-objective, multi-period, and single-product problem that is formulated as a mixed integer non-linear programming model, which can easily be linearized. The objective of this model is to minimize direct or indirect distribution costs. There are six groups of constraints including capacity, input and output balancing, demand satisfaction, network flow continuity, and relative constraints to the required binary variables.     

An MILP model for the reformation of natural gas pipeline networks with hydrogen injection

A mixed integer linear programming (MILP) model is proposed for the reformation of natural gas pipelines. The model is based on the topology of existing pipelines, the load and pressure at each node and the design factors of the region and minimizes the annual substitution depreciation cost of pipelines, the annual construction depreciation cost of compressor stations and the operating cost of existing compressor stations. Considering the nonlinear pressure drop equations, the model is linearized by a piecewise method and solved by the Gurobi optimizer. Two cases of natural gas pipeline networks with hydrogen injection are presented. Several adjustments are applied to the original natural gas pipeline network to ensure that our design scheme can satisfy the safety and economic requirements of gas transportation. Thus, this work is likely to serve as a decision-support tool for the reformation of pipeline networks with hydrogen injection.     

Hydrogen infrastructure strategic planning using multi-objective optimization

Increasingly, hydrogen is being promoted as an alternative energy carrier for a sustainable future. Many argue that its use as a transportation fuel in fuel cell vehicles offers a number of attractive advantages over existing energy sources, especially in terms of well-to-wheel greenhouse gas emissions. Following this interest, several of the leading energy companies, like BP, have started investigating strategies for its introduction. The challenge of developing a future commercial hydrogen economy clearly still remains, though: what are the energy efficient, environmentally benign and cost effective pathways to deliver hydrogen to the consumer? Establishing what these “best” pathways may be is not trivial, given that a large number of technological options exist and are still in development for its manufacturing, storage, distribution and dispensing. Cost, operability, reliability, environmental impacts, safety and social implications are all performance measures that should be considered when assessing the different pathways as viable long-term alternatives. To aid this decision-making process, we present a generic optimization-based model for the strategic long-range investment planning and design of future hydrogen supply chains. By utilizing Mixed Integer Linear Programming (MILP) techniques, the model is capable of identifying optimal investment strategies and integrated supply chain configurations from the many alternatives. Realizing also that multiple performance criteria are of interest, the optimization is conducted in terms of both investment and environmental criteria, with the ultimate outcome being a set of optimal trade-off solutions representing conflicting infrastructure pathways. Since many agree that there is no one single template strategy for investing in a hydrogen infrastructure across the globe, emphasis is placed on developing a generic model such that it can be readily applied to different scenarios, geographical regions and case studies. As such, the model supports BP's strategic hydrogen infrastructure planning using high-level optimization programming, and is coined bpIC-H2. The features and capabilities of the model are illustrated through the application to a case study.     

Simulation of natural gas transmission pipeline network system performance

Simulation has proven to be an effective tool for analyzing pipeline network systems （PNS） in order to determine the design and operational variables which are essential for evaluating the performance of the system. This paper discusses the use of simulation for performance analysis of transmission PNS. A simulation model was developed for determining flow and pressure variables for different configuration of PNS. The mathematical formulation for the simulation model was derived based on the principles of energy conservation, mass balance, and compressor characteristics. For the determination of the pressure and flow variables, solution procedure was developed based on iterative Newton Raphson scheme and implemented using visual C＋＋6. Evaluations of the simulation model with the existing pipeline network system showed that the model enabled to determine the operational variables with less than ten iterations. The performances of the compressor working in the pipeline network system xvhich includes energy consumption, compression ratio and discharge pressure were evaluated to meet pressure requirements ranging from 4000-5000 kPa at various speed. Results of the analyses from the simulation indicated that the model could be used for performance analysis to assist decisions regarding the design and optimal operations of transmission PNS.     

The GAO natural gas supply model

This paper presents a small, annual model of natural gas supply used for policy analysis by the US General Accounting Office. The model incorporates a realistically complex lag structure and complex dynamics while maintaining a simple theoretical framework and manageable size. It simulates the historical record very well and is employed in this paper to generate three scenarios concerning gas supply from 1982–1990 under alternative price control policies.     

Advancing in the decarbonized future of natural gas transmission networks through a CFD study

The injection of green hydrogen into the natural gas grid is a way to decarbonize the gas sector and build an economic transport route for the large-scale delivery of hydrogen. The suitability of the natural gas infrastructure for this purpose depends on the impact that hydrogen may have on the correct operation of its components and understanding the new flow conditions in the system is essential for this aim. Computational studies can anticipate the expected environment in the pipe system, assessing the readiness of the system. However, the experience on this topic is not extensive enough and deeper understanding is necessary. Here we show a CFD study to simulate the transport of H₂/NG blends in a gas setup with the main characteristics of injection sites and gas pipelines representatives of the transmission gas network. This setup considers a blending station, the pumping and injection procedure, and different pipelines geometries to predict the behavior of various mixtures of H₂/NG. It can be seen how (1) a good mixing is achieved in the blending station after a pipe length equivalent to 20–30 diameters is reached; (2) pumping gas by a piston type compressor shows pulsations in the flow regardless the composition of the blend that can be damped implementing mitigation measurements; and (3) asymmetries in the flow are found when the direction of the fluid changes after section reduction, but 20 diameters downstream of the reduction the flow is fully developed.     

A supply model for crude oil and natural gas in the Middle East

Crude oil (CO) and natural gas (NG) play an important role in the world economy. The Arab countries (ACs) share 64% of the total oil reserves and 40% of the NG reserves [OPEC, 2003. The Annual Statistical Bulletin]. On the production side, ACs contribute to 30% and 9% of the world production of CO and NG, respectively. Accurate forecast models are needed to do better planning and create less risky business environment. In this paper, an econometric model is built to capture the behavior of CO and NG production in the ESCWA¹ countries. The model is used to forecast future production trends of CO and NG, and thus provide a powerful tool for researchers, planners and investors working in the energy field.     

Turkey's natural gas policy

This article deals with natural gas policy of Turkey. Natural gas became important in the 1980s. In recent years, natural gas consumption has become the fastest growing primary energy source in Turkey. Natural gas becomes an increasingly central component of energy consumption in Turkey. Current gas production in Turkey meets 3% of the domestic consumption requirements. Natural gas consumption levels in Turkey have witnessed a dramatic increase, from 4.25 Bcm (billion cubic meters) in 1991 to 21.19 Bcm in 2003. Turkish natural gas is projected to increase dramatically in coming years, with the prime consumers expected to be industry and power plants. Turkey has chosen natural gas as the preferred fuel for the massive amount of new power plant capacity to be added in coming years. Turkey has supplied main natural gas need from Russian Federation; however, Turkmen and Iranian gas represent economically sound alternatives. Turkey is in a strategically advantageous position in terms of its natural gas market. It can import gas from a number of countries and diversify its sources. Turkey's motivation for restructuring its natural gas ownership and markets stems from its desire to fulfill EU accession prerequisites in the energy sector.     

Study on the stratification of the blended gas in the pipeline with hydrogen into natural gas

When blending hydrogen into existing natural gas pipelines, the non-uniform concentration distribution caused by the density difference between hydrogen and natural gas will result in the fluctuations of local hydrogen partial pressure, which may exceed the set one, leading to pipeline failure, leakage, measurement error, and terminal appliance. To solve the problem, the H₂–CH₄ stratification in the horizontal and undulated pipe was investigated experimentally and with numerical simulations. The results show that in the gas stagnant situation, hydrogen-methane blending process will cause an obvious stratification phenomenon. The relations between the elevation, pressure, hydrogen fraction, etc., and the gas stratification are figured out. Moreover, even when the blended gas flows at a low rate, the hydrogen-caused stratification should also be considered. Thereafter, the blended gas should be controlled into a situation with low pressure and high speed, which could help to set the pressure, speed, the fraction of H₂.     

综合利用拓展天然气工业发展空间

在世界经济全球化的今天，从客观上了解天然气资源的需求，拓展天然气综合利用空间，培育新的经济增长点，是经济可持续发展战略的重要保证。     

Modeling and estimation of the natural gas consumption for residential and commercial sectors in Iran

In this paper, a logistic based approach is used to forecast the natural gas consumption for residential as well as commercial sectors in Iran. This approach is relatively simple compared with other forecasting approaches. To make this approach even simpler, two different methods are proposed to estimate the logistic parameters. The first method is based on the concept of the nonlinear programming (NLP) and the second one is based on genetic algorithm (GA). The forecast implemented in this paper is based on yearly and seasonal consumptions. In some unusual situations, such as abnormal temperature changes, the forecasting error is as high as 8.76%. Although this error might seem high, one does not need to be deeply concerned about the overall results since these unusual situations could be filtered out to yield more reliable predictions. In general, the overall results obtained using NLP and GA approaches are as well as or even in some cases better than the results obtained using some older approaches such as Cavallini’s. These two approaches along with the gas consumption data in Iran for the previous 10 years are used to predict the consumption for the 11th, 12th, and 13th years. It is shown that the logistic approach with the use of NLP and GA yields very promising results.     

Turkey's natural gas necessity,consumption and future perspectives

Turkey is an important candidate to be the “energy corridor” in the transmission of the abundant oil and natural gas resources of the Middle East and Middle Asia countries to the Western market. Furthermore, Turkey is planning to increase its oil and gas pipeline infrastructure to accommodate its increased energy consumption. Naturally, Turkish natural gas usage is projected to increase remarkably in coming years, with the prime consumers, expected to be industry and power plants. Energy demand of Turkey is growing by 8% annually, one of the highest rates in the world. In addition, natural gas consumption is the fastest growing primary energy source in Turkey. Gas sales started at 0.5 bcm (billion cubic meters), in 1987 and reached approximately 22 bcm in 2003. This article deals with energy policies and natural gas consumption of Turkey. Besides modernization of present lines and realization of capacity increase, new lines will also be needed. In this context, Turkey, due to its geographical location is, in an important position to vary European supply. Therefore, Turkey's role as a transitory area gains importance.     

Long term forecasting of natural gas production

Natural gas is an important energy source for power generation, a chemical feedstock and residential usage. It is important to analyse the future production of conventional and unconventional natural gas. Analysis of the literature determined conventional URR estimates of 10,700–18,300 EJ, and the unconventional gas URR estimates were determined to be 4250–11,000 EJ. Six scenarios were assumed, with three static where demand and supply do not interact and three dynamic where it does. The projections indicate that world natural gas production will peak between 2025 and 2066 at 140–217 EJ/y (133–206 tcf/y). Natural gas resources are more abundant than some of the literature indicates.     

A statistical model for the estimation of natural gas consumption

In this paper we present a statistical approach to natural gas consumption estimation of individual residential and small commercial customers. The approach is based on nonlinear regression principles. Parameters are estimated using mainly two real data sets – ordinary (approximately annual) meter readings of almost all customers and additional (approximately monthly) meter readings designed and operated within the frame of cooperation between the Institute of Computer Science of the Czech Academy of Sciences (ICS) and the West Bohemian Gas Distribution Company, a part of the RWE Group (WBG). The model was tested on various data sets. It has broad applicability in many areas of gas industry.     

The development of natural gas and hydrogen pipeline capital cost estimating equations

Natural gas pipeline cost data collected by the Oil and Gas Journal (O&GJ) [1] for interstate pipelines constructed from 1980 through 2017 were used to develop capital cost estimating equations that are a function of pipeline diameter, length, and U.S. region. Equations were developed for material, labor, miscellaneous, and right-of-way costs, the four cost components in the O&GJ data, for six different regions of the United States (U.S.). Each equation is a function of pipeline diameter and length.Adjustment mechanisms were then developed for converting the natural gas pipeline equations into equations for estimating the costs of hydrogen pipelines. These adjustments were based in part on an analysis completed by the National Institute for Standards and Technology (NIST) [2,3]. The results of this work were used to update cost models in the Hydrogen Delivery Scenario Analysis Model (HDSAM) [4], developed by Argonne National Laboratory for the U.S. Department of Energy's Hydrogen Program. Our analysis shows a wide range of pipeline cost across different U.S. regions, especially with respect to labor and right-of-way costs. The developed cost formulas for hydrogen pipelines are both important and timely as hydrogen is being considered as a zero-carbon energy carrier with the potential to decarbonize all energy sectors, and the cost of hydrogen transportation is essential for techno-economic analysis of its potential use in these sectors.     

Study on leakage and explosion consequence for hydrogen blended natural gas in urban distribution networks

It appears to be the most economical means of transporting large quantities of hydrogen over great distances by the existing natural gas pipeline network. However, the leakage and diffusion behavior of urban hydrogen blended natural gas and the evolution law of explosion characteristics are still unclear. In this work, a Computational Fluid Dynamics three-dimensional simulation model of semi-confined space in urban streets is developed to study the diffusion process and explosion characteristics of hydrogen-blended natural gas. The influence mechanism of hydrogen blending ratio and ambient wind speed on the consequences of explosion accident is analyzed. And the dangerous area with different environmental wind effects is determined through comparative analysis based on the most dangerous scenarios. Results indicate that the traffic flow changes the diffusion path of the jet, the flammable gas cloud forms a complex profile in many obstacles, high congestion level lead to more serious explosion accidents. Wind effect keeps the flammable gas cloud near the vehicle flow, the narrow gaps between the vehicles aggravate the expansion of the flammable gas cloud. When the wind direction is consistent with the leakage direction, hydrogen blended natural gas is gathered in the recirculation zone due to the vortex effect, which results in more serious accident consequences. With the increase in hydrogen blending ratio, the higher content of H and OH in the gas mixture significantly increases the premixed burning rate, the maximum overpressure rises rapidly when the hydrogen blend level increases beyond 40%. The results can provide a basis for construction safety design, risk assessment of leakage and explosion hazards, and emergency response in hydrogen blended natural gas distribution systems.     

A multi-criteria approach to evaluate the natural gas energy systems

This paper aims to select the optimal energetic scenario applied to a consumer with 100 000 inhabitants from the residential–tertiary sector, from the ecological, energetical and economic points of view. A series of seven scenarios based on natural gas has been analyzed. The authors proposed six scenarios for the combined heat and power generation using existing technologies and one scenario for separate generation of the two energy forms. To compare the seven energetic scenarios, the amount of thermal and electrical energy produced by each one had to be the same for a defined time period. To select the optimal energy scenario a multi-criteria NAIADE-based method has been used. Consequently, the optimal energy scenario has been established with respect to criteria groups: ecologic, economic, energetic and global where all criteria groups have been considered. The study results prove that a combined gas and steam turbine cycle is optimal technically, economically and ecologically as it is for each criteria group. A sensitivity analysis has been performed to establish the influence of various parameters in the identification of the optimal energy scenario. For all analyzed scenarios, the optimal energetic scenario is the combined gas and steam turbine cycle.     

Centralisation and decentralisation in strategic municipal energy planning in Denmark

Denmark's future energy system is to be entirely based on renewable energy sources. Municipalities will play an important role as local energy planning authorities in terms of adopting and refining this vision in different local contexts. Based on a review of 11 municipal energy plans, this paper examines to what extent municipal energy planning matches national 100% renewable energy strategies. The results indicate a willingness among Danish municipalities to actively carry out energy planning, and the plans reveal a large diversity of (new) activities. At the same time, however, there is a strong need for better coordination of municipal energy planning activities at the central level. It is suggested that the role of municipalities as energy planning authorities needs to be outlined more clearly in, e.g., strategic energy planning which integrates savings, efficiency and renewable energy in all (energy) sectors. This requires the state to provide municipalities with the necessary planning instruments and establish a corresponding planning framework. Consequently, there is a need for a simultaneous centralisation and decentralisation during the implementation of the 100% renewable energy vision. The paper outlines a basic division of tasks between the central and the local level within such a strategic energy planning system.