Energy security is a multidimensional and multifaceted concept, therefore defining it is a complex problem. It requires the consideration of a wide set of factors from the fields of economics, geology, ecology and geopolitics, all of which have an influence on energy security or the lack thereof. The article focuses on natural gas, which is a very specific fuel in the European context. It is the most “politicized” source of energy, as a consequence of its growing importance as a transition fuel in the energy transformation process. In order to identify dependencies between variables on the gas market and analyze their impact on it (in particular on underground storage), the authors chose a set of variables and built a Bayesian network. The network is an effective and flexible tool that allows analysis of the relationships between the variables that build them and model their values based on evidence. The article presents two stages of work with the Bayesian network. In the first one, a... [more]

As the natural gas pipeline network becomes larger and more complicated, a stricter requirement of computation efficiency for the large and complicated network transient simulation should be proposed. The adaptive time step method has been widely used in the transient simulation of natural gas pipeline networks as a significant way to improve computation efficiency. However, the trial calculation process, which is the most time-consuming process in time step adjustment, was used to adjust the time step in these methods, reducing the efficiency of time step adjustment. In order to reduce the number of trial calculations, and improve the calculation efficiency, an improved adaptive time step method is proposed, which proposes the concept of energy number and judges the energy number of the boundary conditions after judging whether the variation of the pipeline state is tolerable. A comparison between the adaptive time step method and the improved adaptive time step method in the restart... [more]

The war in Ukraine has sensitized German policy makers towards the negative economic impact of a curtailment of natural gas flows from Russia. Given its large import dependency, Germany has implemented regulatory measures for mitigating a possible gas shortage and is seeking to diversify from pipeline imports of liquefied natural gas (LNG). In this context, we provide a comprehensive review of the natural gas crisis in Europe and place it in the context of the peculiar role of natural gas in Germany. We critically discuss the economic impact of an embargo, and assess demand and supply factors capable of mitigating a supply shortage. We derive a short-term import substitution potential of 13 bcm, assuming timely installation of Floating Storage and Regasification Units (FSRUs). We discuss the potential for demand reductions in the power sector, in industry consumption, and in households, and estimate a combined maximum of 24.1 bcm. Under decreased industrial demand, the most optimistic... [more]

An active prechamber turbulent ignition system is a forced ignition method for internal combustion engines fueled with low reactivity fuels, i.e., natural gas and gasoline, which could expand the lean-burn limit, promote flame propagation, and ensure cyclic stability. In the present study, the effects of charge concentration stratifications inside the prechamber on the jet characteristics and combustion process were numerically investigated using CONVERGE software coupled with a reduced methane mechanism by the coupling control of spark timing and prechamber global equivalence ratio. The results show that the jet characteristics and ignition mechanisms can be regulated by controlling the prechamber global equivalence ratio and spark timing. On the one hand, as the prechamber global equivalence ratio increases, the velocity of the jet increases firstly and then decreases, the temperature drops, and OH and CH2O radicals are reduced, but the stable combustion intermediates, CO and H2, are... [more]

This study analyzes European natural gas (NG) prices since the eve of the 2008 financial crisis. Spearman’s rank correlation coefficients associate prices with and without taxation, whereas a hierarchical clustering analysis clarifies similarities in NG pricing behavior. After performing econometric tests to ensure the satisfaction of classical hypotheses and identify a system of endogenous variables, structured unrestricted and restricted vector autoregressive models are applied to panel data composed of 34 spatial units and 31 units of time drawn from 2007−2022 to confirm the presence of short-term and long-term causal dependencies. The nonparametric analysis identifies three groups of countries that exhibit a differentiated pricing behavior. The parametric analysis reveals a significant and asymmetric short run relation, which is imposed by liquefied natural gas (LNG) imports from Nigeria on the logarithm of NG prices. However, the sign of coefficients associated with lagged LNG imp... [more]

Dual fuel combustion leverages a high-reactivity fuel (HRF) to ignite a premixed low reactivity fuel (LRF)−air mixture to achieve high efficiencies and low engine-out emissions. The difference in the relative amounts of these fuels and in-cylinder fuel reactivity stratification profoundly impacts dual fuel combustion. The effect of increasing LRF energy substitution on dual fuel combustion at various fixed HRF (diesel) quantities was experimentally studied for two different LRFs (natural gas and propane) on a heavy-duty single cylinder engine at a constant intake pressure of 1.5 bar and injection pressure of 500 bar. Further, this effect was studied for three different HRF start of injection (SOI) timings of 310 CAD (50° BTDC), 330 CAD (30° BTDC), and 350 CAD (10° BTDC). For 310 CAD SOI, increasing the LRF substitution at a fixed HRF resulted in higher loads, peak cylinder pressures, and peak apparent heat release rates (AHRR). The onset of low temperature heat release (LTHR) was advan... [more]

The blending of hydrogen gas into natural gas pipelines is an effective way of achieving the goal of carbon neutrality. Due to the large differences in the calorific values of natural gas from different sources, the calorific value of natural gas after mixing with hydrogen may not meet the quality requirements of natural gas, and the quality of natural gas entering long-distance natural gas and urban gas pipelines also has different requirements. Therefore, it is necessary to study the effect of multiple gas sources and different pipe network types on the differences in the calorific values of natural gas following hydrogen admixing. In this regard, this study aimed to determine the quality requirements and proportions of hydrogen-mixed gas in natural gas pipelines at home and abroad, and systematically determined the quality requirements for natural gas entering both long-distance natural gas and urban gas pipelines in combination with national standards. Taking the real calorific val... [more]

During petroleum industry operations, burning flammable gas components in the flaring stacks is common, normally a symbol for stable production, but flaring these components creates harmful emissions for the environment. This flaring gas has components with a high quantity of heating power, an important measurement that quantifies the energy that can potentially be obtained from this wasted resource. This paper aims to evaluate the energy usage of the flaring gas, estimating the possible energy produced with this usable resource by modeling a treatment and energy generation process employing the Aspen HYSYS® simulator. The flaring gas is characterized using different models and compositional ranges of natural gas to know what kind of gas it is and identify what type of equipment could be used for treatment and energy generation from this resource. After the gas characterization, the selection of the equipment of treatment and energy generation is necessary; this is done using a multicr... [more]

European countries are required to look for alternative gas suppliers to deliver energy security for Europe. Qatar has been proposed to be an alternative gas supplier; however, there are problems that limit Qatar from exporting more gas to Europe, namely: the limited LNG quantities available for export, the long-term fixed contracting strategy, and the lack of room to receive additional gas in European LNG terminals. As these problems are critical and limit Qatar from exporting more gas to Europe, this research aims to propose potential solutions to overcome them. The results show that to solve the issue of the limited LNG quantities available for export, Qatar can produce electricity from renewable sources and export the gas consumed for power production, and can produce renewable natural gas (RNG) from green hydrogen and captured carbon dioxide. Two BCM of natural gas can be exported if 15% of the electricity required is produced from renewables in Qatar. In addition, 0.45 BCM of RNG... [more]

Green hydrogen exploitation plays a crucial role in achieving carbon neutrality by 2050. Hydrogen, in fact, provides a number of key benefits for the energy system, due to its integrability with other clean technologies for energy production and consumption. This paper is aimed at presenting the project of recovery of an abandoned industrial area located in central Italy by developing a site for the production of green hydrogen. To this aim, the analysis of the territorial and industrial context of the area allowed us to design the project phases and to define the sizing criteria of the hydrogen production plant. The results of a preliminary cost−benefit analysis show that a huge initial investment is required and that, in the short term, the project is sustainable only with a very large public grant. On the other hand, in the long term, the project is sustainable, and the benefits significantly overcome the costs.

To meet the target of reducing greenhouse gas emissions, hydrogen as a carbon-free fuel is expected to play a major role in future energy supplies. A challenge with hydrogen is its low density and volumetric energy value, meaning that large tanks are needed to store and transport it. By injecting hydrogen into the natural gas network, the transportation issue could be solved if the hydrogen−natural gas mixture satisfies the grid gas quality requirements set by legislation and standards. The end consumers usually have stricter limitations on the gas quality than the grid, where Euromot, the European association of internal combustion engine manufacturers, has specific requirements on the parameters: the methane number and Wobbe index. This paper analyses how much hydrogen can be added into the natural gas grid to fulfil Euromot’s requirements. An average gas composition was calculated based on the most common ones in Europe in 2021, and the results show that 13.4% hydrogen can be mixed... [more]

Gas reservoirs discovered in the southern margin of the Junggar Basin generally have high temperatures (up to 172.22 °C) and high pressures (up to 171.74 MPa). If using the PVT laboratory to get the gas compressibility factor, data from the laboratory are so little that it will not satisfy the demands of reservoir engineering calculations. There are many empirical correlations for calculating the Z-factor; however, these correlations give large errors at high gas reservoir pressures. The errors in estimating the Z-factor will lead to large errors in estimating all the other gas properties such as gas formation volume factor, gas compressibility, and gas in place. In this paper, a new accurate Z-factor correlation has been developed based on PVT data by correcting the high-pressure part of the most commonly used Dranchuk-Purvis-Robinson Correlation. Multivariate nonlinear regression is used to establish the independent variable function of pseudo-critical temperatures and pressures. By... [more]

The pressure at the natural gas wellhead typically ranges from tens to hundreds of atmospheres. Traditionally, the wellhead pressure must be throttled into a low level to satisfy the requirement of gathering pipelines, in which a large amount of pressure energy is wasted. The high-pressure oil−gas turbine is a promising approach to convert the wellhead pressure energy into shaft power or electricity. In this paper, a numerical investigation is conducted on a radial-outflow high-pressure oil−gas turbine utilized in a wellhead pressure power generation system. Using the self-defined real oil−gas physical properties and Computational Fluid Dynamics (CFD), the internal flow and performance of the high-pressure oil−gas turbine under complex operating conditions are investigated. To improve the turbine flow and performance, a Latin Hypercube Sampling-based parametric tuning is performed on the stator and rotor blade geometries. The application of such an approach effectively adjusts the flow... [more]

The reduction of carbon emissions from the energy industry chain and the coordinated development of the energy supply chain have attracted widespread attention. This paper conducts a systematic review of the existing literature on the energy industry chain and energy supply chain. Based on the analytical results, this paper finds that research gaps exist in the studies of energy consumption structure and resource consumption in energy industry chain. In addition, the studies of coordinated operation mechanisms, risk control and the impact of government policies on the energy supply chain still have some shortcomings. Furthermore, this paper shows that the exploitation and utilization of renewable energy and the sustainable development of the energy industry chain and supply chain have become the major focus of scholars and governments in recent years. Accordingly, this article finally presents the future research prospects and provides managerial insights for policy makers and enterpri... [more]

Worldwide concerns over energy optimization and harnessing have sparked a variety of research on utilizing wasted energy. Natural gas, in particular, has been an essential energy commodity for domestic and industrial applications. This paper approaches the same principle throughout the Egyptian natural gas conventional national grid. The real case of Egypt’s Al-Alamein city gas line extension is analytically studied for energy harness. Thus, this paper aims to study the replacement of conventional energy-wasting pressure-reducing stations with power-producing expander generator systems to utilize pressure reduction in electricity generation. The mathematical equations that describe the energy recovery processes are presented. Reliable commercial software is used to verify the possible implementation of turbo expander stations in three scenarios. Each scenario is defined, and its main components and numerical parameters are introduced. Hence, the resulting energy outputs and applicabili... [more]

How dependent are European power systems and economies on natural gas? To answer this pressing question, we coupled a simulation model for assessing security of electricity supply and an economic optimization model. With this, we were able to analyze different reduction scenarios of the amount of gas utilized in the power sector. Our results show that reducing the amount of natural gas in the European power sector by up to 30% has a relatively moderate impact on the security of electricity supply. Restrictions of 40% or more result in substantially higher reductions in electricity demand shortfall and are associated with economic costs of more than EUR 77 billion. Furthermore, we demonstrate that a close coordination of gas distribution on a European level would be instrumental in mitigating negative economic consequences. Finally, it can be deduced that a coordinated delay of planned power plant shutdowns could effectively compensate for reduced gas volumes in the electricity sector.

Despite the considerable breakthrough in district heating systems (DHS) globally, there is not yet any policy on developing this technology in Iran. This country has a high range of energy demand, while renewable energies play a minor role in its energy supply chain. Furthermore, the world is going through a transition towards renewable resources, which currently consist of only 10% of the total energy mix. As the first contribution in this area, this paper aims to design a 100% renewable DHS integrated with radiant floor heating for a group of residential buildings in Sarein, Iran. Moreover, the literature proposes a novel approach for combining geothermal energy and Municipal Solid Waste (MSW) to achieve a 100% renewable energy system. Building Information Modeling (BIM) is used for thermal analysis by 3D designing the buildings in SketchUp and OpenStudio and simulating the heat load in EnergyPlus. Three scenarios are presented to better compare the DHS with the decentralized heating... [more]

The application of expansion turbines at natural gas pressure reduction stations (PRS) is considered in order to recover energy contained in the natural gas. This energy is irretrievably lost at the reduction stations which use the traditional pressure reducer. Expanders allow for the electricity production for PRS own needs and for resale. The paper presents an analysis of the possibility of using turboexpanders at PRS in Poland. Authors performed static simulations for the assumed data sets and dynamic simulations for annual data from selected representative natural gas reduction and measurement stations. Energy balances are presented for the discussed scenarios that compare the energy requirements of natural gas pressure reduction stations which use a classic pressure reducer or turboexpander (TE). Using static simulations, authors investigated whether the use of a turboexpander is economically justified for the case if it is used only to supply the reduction station with electricit... [more]

Energy Intensive Industries (EII) are high users of energy and some of these facilities are extremely dependent on Natural Gas for processing heat production. In European countries, where Natural Gas is mostly imported from external producers, the increase in international Natural Gas prices is making it difficult for some industries to deliver the required financial results. Therefore, they are facing complex challenges that could cause their delocalization in regions with lower energy costs. European countries lack on-site Natural Gas resources and the plans to reduce greenhouse gas emissions in the industrial sector make it necessary to find an alternative. Many different processes cannot be electrified, and in these cases, synthetic methane is one of the solutions and also represents an opportunity to reduce external energy supply dependency. This study analyzes the current development of power-to-gas technological solutions that could be implemented in large industrial consumers t... [more]

Nowadays, modern gas supply systems are complex. They consist of gas distribution stations; high-, medium-, and low-pressure gas networks; gas installations; and control points. These systems are designed to provide natural gas to the population, including domestic, industrial, and agricultural consumers. This study is aimed at developing methods for improving the calculation of gas distribution networks. The gas supply system should ensure an uninterrupted and safe gas supply to consumers that is easy to operate and provides the possibility of shutting down its individual elements for preventive, repair, and emergency recovery work. Therefore, this study presents a mathematical calculation method to find the optimal operating conditions for any gas network during the period of seasonal changes in thermal loads. This method demonstrates how the reliability of gas distribution systems and resistance to non-standard critical loads are affected by consumers based on the time of year, mont... [more]

With the recent push towards high injection rate blast furnace operation for economic and environmental reasons, it has become desirable in North America to better understand the impacts of alternate injected gas fuels in comparison to the well-documented limitations of natural gas. The quenching effects of gas injection on the furnace present a functional limit on the maximum stable injection rate which can be utilized. With this in mind, researchers at Purdue University Northwest’s Center for Innovation through Visualization and Simulation utilized previously developed computational fluid dynamics (CFD) models of the blast furnace to explore the impacts of replacing natural gas with syngas in a blast furnace with a single auxiliary fuel supply. Simulations predicted that the syngas injection can indeed reduce coke consumption in the blast furnace at similar injection rates to natural gas while maintaining stable raceway flame and reducing gas temperatures. The coke rates predicted by... [more]

When a PIV flowmeter is used to measure a large flow of natural gas, the flow field fluctuation and particle distribution have a significant influence on the measurement accuracy and the particle injection mode plays a key role in the flow field fluctuation and particle distribution. To improve the measurement accuracy of PIV flowmeters, the method of filling tracer particles in single pipes, multiple pipes, and L pipes of a natural gas DN100 pipeline under high-pressure working conditions was compared and analyzed through numerical calculation and testing. The results show that the disturbance distance of filling particles in L pipes was the shortest, but the particle distribution area was small, whereas the flow metering error was large. By shortening the intersection distance between the L tube injection flow field and the main flow field, the problem that the particles failed to fill the test area was effectively solved, and the peak turbulence intensity at the intersection of the... [more]

There are two important territories in Slovakia with functioning gas well operations: the Eastern Slovak Lowland and the Vienna Basin. This article focuses on the creation of electronic monitoring and graphical mapping of the current technical conditions of gas wells in the Eastern Slovak Lowland. An analysis of the gas wells’ current state in the terrain is available. The aim of the article is to draw attention to the current state of gas wells, such as the insufficient processing of gas wells, the lack of summary and uniform records concerning them, and the lack of an electronic system for monitoring the technical security of the wells. The scientific contribution of this article lies in its ability to interpret and address operational problems related to gas wells. Through analogy, the step algorithm expresses the possibility of also using gas wells for oil, geothermal and hydrogeological wells. The intention was to highlight the importance of the need to create a database for the s... [more]

The oxidative coupling of methane (OCM) process is considered an intriguing route for the production of ethylene, one of the most demanded petrochemical products on the market. Ethylene can be produced by various methods, but the most widely used is the steam cracking process. However, due to the current instability of the crude oil market and the shale gas revolution, the production of olefins from natural gas has opened a new path for companies to mitigate the high demand for crude oil while utilizing an abundant amount of natural gas. In this work, the OCM process was compared with other existing processes, and the process was simulated using Aspen HYSYS. The flowsheet was divided into four sections, namely (i) the reaction section, (ii) the water removal section, (iii) the carbon dioxide capture section, and (iv) the ethylene purification section. Each section was thoroughly discussed, and the heat integration of the process was performed to ensure maximum energy utilization. The h... [more]

Gas−liquid separation at natural gas wellheads has always been a key technical problem in the fields of natural gas transportation and storage. Developing a gas−liquid separation device that is both universal and highly efficient is the current challenge. A new type of combined gas−liquid separation device was designed in this study, and the efficiency of the separator was studied using a laser Doppler anemometer and phase Doppler particle analyzer at a flow rate of 10−60 Nm3/h. The results showed that the separation efficiency of the combined separator was above 95% at each experimental flow rate, verifying the strong applicability of the combined separator. Moreover, the separation efficiency was as high as 99% at the flow rates of 10 and 60 Nm3/h, thereby realizing efficient separation. This study is significant to the development of gas−liquid separation devices.