Nowadays, an accurate and precise description of the combustion phase is essential in spark-ignition (SI) engines to drastically reduce pollutant and greenhouse gas (GHG) emissions and increase thermal efficiency. To this end, computational fluid dynamics (CFD) can be used to study the different phenomena involved, such as the ignition of the charge, combustion development, and pollutant formation. In this work, a validation of a CFD methodology based on the flame area model (FAM) was carried out to model the combustion process in light-duty SI engines fueled with natural gas. A simplified spherical kernel approach was used to model the ignition phase, whereas turbulent flame propagation was described through two variables. A zero-dimensional evolution of the flame kernel radius was used in combination with the Herweg and Maly formulation to take the laminar-to-turbulent flame transition into account. To estimate the chemical composition of burnt gas, two different approaches were cons... [more]

Conventional economic theory indicates that the free market contributes to allocative efficiency. However, specific energy markets present network industry characteristics which distance them from perfect competition. These markets, therefore, need effective regulation. The liberalizing reforms which took place in the Organization for Economic Cooperation and Development (OECD) and emerging countries from the 1990s onwards have reduced the share of state ownership in the energy sector, but not its functions of regulation, coordination and planning. It is also worth noting the expansion of the government’s agenda due to the energy transition that has unequivocally imposed itself in the 21st century. This article uses the Slacks-Based Measure of the Data Envelopment Analysis (SBM-DEA) methodology to investigate the relationship between market liberalization and sustainability in a low-carbon energy transition context. Taking the cases of the natural gas and electricity markets, we verify... [more]

This research was conducted to study the flame instability of syngas derived from raw municipal solid waste (MSW) and its potential as a natural gas (NG) replacement in power generation. MSW syngas is a mixture of various components such as methane (CH4), nitrogen (N2), oxygen (O2), and hydrogen (H2), whereas NG is mainly composed of CH4 (>70%) and CO2 (>10%). The flame characteristics of these two gases are quite different thus a direct replacement of NG with MSW syngas is impossible. Improvements to MSW syngas combustion are needed through the augmentation of the gas with CH4 and H2 active additives at various ratios so that its flame characteristics are comparable to those of NG. A typical MSW syngas composed of 16.2% methane (CH4), 13.5% hydrogen (H2), 69.1% nitrogen (N2), and 0.6% oxygen (O2) (by vol.) is available in Thailand with great potential for use as an NG replacement. In this study, this gas is used as a representative fuel for improvement and is referred to as simulated... [more]

The article discusses the results of biomonitoring research at the Underground Gas Storage (UGS). Hydrogen sulphide, as one of the products of microbiological reaction and transformation, as well as a product of chemical reactions in rocks, is a subject of interest for global petroleum companies. The materials used in this research work were formation waters and stored natural gas. The biomonitoring of reservoir waters and cyclical analyses of the composition of gas stored at UGS Wierzchowice enabled the assessment of the microbiological condition of the reservoir environment and individual storage wells in subsequent years of operation. Investigations of the formation water from individual wells of the UGS Wierzchowice showed the presence of sulphate reducing bacteria bacteria (SRB), such as Desulfovibrio and Desulfotomaculum genera and bacteria that oxidize sulphur compounds. In the last cycles of UGS Wierzchowice, the content of hydrogen sulphide and sulphides in the reservoir water... [more]

To solve the contradiction between achieving long-term economic growth and reducing the consumption of certain types of resources, the concept of sustainable resource saving economic development must be put into practice. The purpose of this research is to establish criteria, develop indicators, and identify factors of the sustainable energy-saving economic development, as well as to test the developed theoretical provisions using the example of natural gas consumption by different countries. To achieve this goal, various methods were used, including economic and mathematical modeling, time series analysis, factor analysis, regression analysis, and so on. The criteria were formalized, according to which a certain type of economic development can be attributed to energy saving both at the level of the state economy as a whole and at the level of individual industries and enterprises. It was established that the formalized criteria of the sustainable energy-saving economic development ha... [more]

The ability to accurately forecast the spot price of natural gas benefits stakeholders and is a valuable tool for all market participants in the competitive gas market. In this paper, we attempt to forecast the natural gas spot price 1, 3, 5, and 10 days ahead using machine learning methods: support vector machines (SVM), regression trees, linear regression, Gaussian process regression (GPR), and ensemble of trees. These models are trained with a set of 21 explanatory variables in a 5-fold cross-validation scheme with 90% of the dataset used for training and the remaining 10% used for testing the out-of-sample generalization ability. The results show that these machine learning methods all have different forecasting accuracy for every time frame when it comes to forecasting natural gas spot prices. However, the bagged trees (belonging to the ensemble of trees method) and the linear SVM models have superior forecasting performance compared to the rest of the models.

Although both aggregate and per capita energy consumption in Bangladesh is increasing rapidly, its per capita consumption is still one of the lowest in the world. Bangladesh gradually shifted from petroleum-based energy to domestically sourced natural-gas-based energy sources, which are predicted to run out within next two decades. The present study first identified the determinants of aggregate commercial energy and its three major components of oil, natural gas, and coal demand for Bangladesh using a simultaneous equations framework on an annual database covering a period of 47 years (1972−2018). Next, the study forecast future demand for aggregate commercial energy and its three major components for the period of 2019−2038 under the business-as-usual and ongoing COVID-19 pandemic scenarios with some assumptions. As part of a sensitivity analysis, based on past trends, we also hypothesized four alternative GDP and population growth scenarios and forecast corresponding changes in tota... [more]

With the recent rising attention and debates on the role of natural gas, especially liquid natural gas, in energy transition, it is critical to have a consistent approach in assessing uncertainties and dynamics in the global gas market during the next two to three decades. There are two objectives of this paper. The first one is to estimate and discuss the impacts of the global liquified natural gas (LNG) trade under a low-carbon scenario using a partial equilibrium model. The second objective is to discuss the role of a structural economic model in empirical analysis and strategy design under a regime shift, such as an energy transition, for the global natural gas market.

The energy sector in Poland is currently calling for dynamic redevelopment and cleaner energy. This country is world famous for its high level of coal production, from which it does not want to retreat in the next two decades. For this reason, it is safer to gradually reduce the use of coal while increasing the consumption of gas and simultaneously developing green energy. However, the Polish gas sector is still dependent on Russian gas supplied through the Yamal gas pipeline. Taking into consideration Polish geopolitics, this state of affairs poses a huge challenge and a threat to Poland’s energy security. That is why the concept of the North-South Gas Corridor was introduced. It is intended to be a network of gas pipelines that connect the countries of Central and South Europe to two gas terminals (in Poland and Croatia), which will supply gas from a chosen source. This article presents the current condition of the gas sector in Poland. It focuses on the North-South Gas Corridor proj... [more]

The liberalization of the gas market has deeply affected the structure of the gas system. The change from a vertically integrated utility structure to a liberalized architecture has resulted in a new network asset where aggregators could play a key role. To enable aggregators’ functionalities, the gas system has moved to a smart configuration. The development of this Advanced Metering Infrastructure (AMI) allowing a two-way communication between the utility and the consumers, together with demand response programs, prove to be an advantageous solution. Utilities are allowed to manage consumers’ gas load by asking them to reduce or shift their gas usage so that rebates or back payments could be available for consumers. In this framework, aimed at ensuring the feasibility of the gas system and promoting the aggregation of small gas loads, a new agent has been identified. In this research, the potential of district heating systems as gas market aggregators, together with a novel architect... [more]

Azerbaijan signed the Paris Agreement in 2016 and committed to cut greenhouse gas (GHG) emissions by 35% in 2030. Meanwhile, natural gas has been vital component in the total energy mix of Azerbaijan economy and accounted for almost 65% of the total energy consumption. In the overall electricity mix, natural gas-fired power plants generate 93% of the country’s electricity. Since global energy consumption is responsible for 73% of human-caused greenhouse-gas emissions, and CO2 makes up more than 74% of the total, this study investigates possible mitigation effects of the natural gas consumption on CO2 emissions for Azerbaijan. Author employed several cointegration methodologies, namely Bound testing Autoregressive Distributed Lag (ARDL) approach, Fully Modified Ordinary Least Squares (FMOLS), Dynamic Ordinary Least Squares (DOLS), and Structural Time Series model (STSM). Author of this paper found that when the share of natural gas increases 1 percent in the total energy mix, CO2 emissi... [more]

The transmission of natural gas is a key element of the Polish energy system. The published data of the Polish distribution system operators and the transmission system operator on the volume of gaseous fuel transmitted indicate a growing trend in the consumption of energy produced from natural gas. In connection with the energy transformation, switching energy generation sources from hard coal to natural gas in Poland, it is important for transmission operators to know the future demand for gaseous fuel. The aim of the article is to attempt to develop an econometric model related to the consumption of gaseous fuel by Polish entrepreneurs. The knowledge therein may be useful for making business decisions related to the possible expansion of the transmission system, and thus investing financial resources for this purpose. This knowledge will also provide quantitative information related to the interest in gaseous fuel among industrial consumers and the analysis of the trend of natural g... [more]

The flammable hydrogen-blended methane−air and natural gas−air mixtures raise specific safety and environmental issues in the industry and transportation; therefore, their explosion characteristics such as the explosion limits, explosion pressures, and rates of pressure rise have significant importance from a safety point of view. At the same time, the laminar burning velocities are the most useful parameters for practical applications and in basic studies for the validation of reaction mechanisms and modeling turbulent combustion. In the present study, an experimental and numerical study of the effect of hydrogen addition on the laminar burning velocity (LBV) of methane−air and natural gas−air mixtures was conducted, using mixtures with equivalence ratios within 0.90 and 1.30 and various hydrogen fractions rH within 0.0 and 0.5. The experiments were performed in a 14 L spherical vessel with central ignition at ambient initial conditions. The LBVs were calculated from p(t) data, determ... [more]

Blending hydrogen into the natural gas infrastructure is becoming a very promising practice to increase the exploitation of renewable energy sources which can be used to produce “green” hydrogen. Several research projects and field experiments are currently aimed at evaluating the risks associated with utilization of the gas blend in end-use devices such as the gas meters. In this paper, the authors present the results of experiments aimed at assessing the effect of hydrogen injection in terms of the durability of domestic gas meters. To this end, 105 gas meters of different measurement capabilities and manufacturers, both brand-new and withdrawn from service, were investigated in terms of accuracy drift after durability cycles of 5000 and 10,000 h with H2NG mixtures and H2 concentrations of 10% and 15%. The obtained results show that there is no metrologically significant or statistically significant influence of hydrogen content on changes in gas meter indication errors after subject... [more]

We extend the widely-studied Heterogeneous Autoregressive Realized Volatility (HAR-RV) model to examine the out-of-sample forecasting value of climate-risk factors for the realized volatility of movements of the prices of crude oil, heating oil, and natural gas. The climate-risk factors have been constructed in recent literature using techniques of computational linguistics, and consist of daily proxies of physical (natural disasters and global warming) and transition (U.S. climate policy and international summits) risks involving the climate. We find that climate-risk factors contribute to out-of-sample forecasting performance mainly at a monthly and, in some cases, also at a weekly forecast horizon. We demonstrate that our main finding is robust to various modifications of our forecasting experiment, and to using three different popular shrinkage estimators to estimate the extended HAR-RV model. We also study longer forecast horizons of up to three months, and we account for the poss... [more]

Hydrogen is increasingly receiving a primary role as an energy vector in ensuring the achievement of the European decarbonization goals by 2050. In fact, Hydrogen could be produced also by electrolysis of water using renewable sources, such as photovoltaic and wind power, being able to perform the energy storage function, as well as through injection into natural gas infrastructures. However, hydrogen injection directly impacts thermodynamic properties of the gas itself, such as density, calorific value, Wobbe index, sound speed, etc. Consequently, this practice leads to changes in metrological behavior, especially in terms of volume and gas quality measurements. In this paper, the authors present an overview on the impact of hydrogen injection in natural gas measurements. In particular, the changes in thermodynamic properties of the gas mixtures with different H2 contents have been evaluated and the effects on the accuracy of volume conversion at standard conditions have been investig... [more]

To reduce the greenhouse effect, it is important to reduce not only carbon dioxide but also methane emissions. Methane gas can be not only a fossil fuel (natural gas) but also a renewable energy source when it is extracted from biomass. After biogas has been purified, its properties become closer to those of natural gas or methane. Natural gas is an alternative energy source that can be used for spark-ignition engines, but its physicochemical properties are different from those of gasoline, and the spark-ignition engine control parameters need to be adjusted. This article presents the results of a study that considers a spark-ignition engine operating at different speeds (2000 rpm, 2500 rpm, and 3000 rpm) and the regulation of the timing of intake valve closure when the throttle is partially open (15%), allowing the engine to maintain the stoichiometric air−fuel mixture and constant spark timing. Studies have shown a reduction in engine break torque when petrol was replaced by natural... [more]

This work aims to present an analysis of electricity and natural gas supply security in the four European Union countries with the highest level of consumption, namely Germany, France, Italy, and Spain. The goal of the study is to use and adapt a set of 22 indicators for estimating the level of energy security. The evaluation of an index called “Energy Security Level”, measuring the overall energy security, is performed for the period 2006−2018 in order to compare its evolution in each of the analyzed countries. The application of the proposed indicator system demonstrates which measures weakened or strengthened energy security in the past. The analysis of the energy security level demonstrates that Germany and France perform better than Italy and Spain in terms of energy security assurance. The main factors for these differences are the rich energy mix for Germany and the massive presence of nuclear power in France. These two elements make German and French energy systems more resilie... [more]

While operating at light loads, diesel pilot-ignited natural gas engines with lean premixed natural gas suffer from poor combustion efficiency and high methane emissions. This work investigates the limits of low-load operation for a micro-pilot diesel natural gas engine that uses a stoichiometric mixture to enable methane and nitrogen oxide emission control. By optimizing engine hardware, operating conditions, and injection strategies, this study focused on defining the lowest achievable load while maintaining a stoichiometric equivalence ratio and with acceptable combustion stability. A multi-cylinder diesel 6.7 L engine was converted to run natural gas premix with a maximum diesel micro-pilot contribution of 10%. With a base diesel compression ratio of 17.3:1, the intake manifold pressure limit was 80 kPa(absolute). At a reduced compression ratio of 15:1, this limit increased to 85 kPa, raising the minimum stable load. Retarding the combustion phasing, typically used in spark-ignitio... [more]

This article highlights the need to reduce carbon dioxide emissions by reducing energy consumption. Of course, this can be achieved in various ways, but inter alia, through the practical implementation of the assumptions contained in the CSR programs of individual companies, which include a component on environmental protection and counteracting global warming. The authors also describe a proposal to reduce CO2 emissions by using coke oven gas (if necessary) in exchange for natural gas. Currently, the largest sources of carbon dioxide emissions are the combustion of fossil fuels in power plants, transport—cars and planes, processes related to the production of industrial goods, and deforestation. In the preparation of the article, the analysis of the literature on the subject, analysis of documents, desk research, and two case studies were used. The main goal of the article is to present the possibilities of reducing CO2 emissions by implementing the assumptions of the CSR policy on th... [more]

Simulating the phase behavior of a reservoir fluid requires the determination of many parameters, such as gas−oil ratio and formation volume factor. The determination of such parameters requires knowledge of the critical properties and compressibility factor (Z factor). There are many techniques to determine the compressibility factor, such as experimental pressure, volume, and temperature (PVT) tests, empirical correlations, and artificial intelligence approaches. In this work, two different models based on statistical regression and multi-layer-feedforward neural network (MLFN) were developed to predict the Z factor of natural gas by utilizing the experimental data of 1079 samples with a wide range of pseudo-reduced pressure (0.12−25.8) and pseudo reduced temperature (1.3−2.4). The statistical regression model was proposed and trained in R using the “rjags” package and Markov chain Monte Carlo simulation, while the multi-layer-feedforward neural network model was postulated and train... [more]

Several North American utilities are planning to blend hydrogen into gas grids, as a short-term way of addressing the scalable demand for hydrogen and as a long-term decarbonization strategy for ‘difficult-to-electrify’ end uses. This study documents the impact of 0−30% hydrogen blends by volume on the performance, emissions, and safety of unadjusted equipment in a simulated use environment, focusing on prevalent partially premixed combustion designs. Following a thorough literature review, the authors describe three sets of results: operating standard and “ultra-low NOx” burners from common heating equipment in “simulators” with hydrogen/methane blends up to 30% by volume, in situ testing of the same heating equipment, and field sampling of a wider range of equipment with 0−10% hydrogen/natural gas blends at a utility-owned training facility. The equipment was successfully operated with up to 30% hydrogen-blended fuels, with limited visual changes to flames, and key trends emerged: (a... [more]

Combatting climate change necessitates a substantial global increase in renewable electricity capacity. Many low-income and lower-middle-income countries suffer from unfavorable green financing conditions. Fifteen of these countries possess substantial natural gas reserves. To overcome green financing constraints in such countries, we propose an integrated energy contract that awards a renewable energy project in parallel with an upstream natural gas project to interested energy companies. The state returns from the natural gas project provide a guarantee for renewable energy investments, reducing their associated risks. We conduct Monte Carlo simulations for each of the targeted countries after populating the input parameters for the upstream natural gas and renewable energy projects, including forecasting country-specific natural gas prices. When accounting for 10% of their existing natural gas reserves in the proposed contract, Nigeria, Myanmar, and Indonesia can achieve more than 6... [more]

This article discusses methods of enhanced power generation using a binary power system with low-boiling fluid as an intermediate energy carrier. The binary power system consists of micro-gas and steam power units and is intended for remote standalone power supply. Trifluotrichloroethane was considered as the working agent of the binary cycle. The developed system was modeled by two parts in MATLAB Simulink and Aspen HYSYS. The model in Aspen HYSYS calculates the energy and material balance of the binary energy system. The model in MATLAB Simulink investigates the operation of power electronics in the energy system for quality power generation. The results of the simulation show that the efficiency of power generation in the range of 100 kW in the developed system with micro-turbine power units reaches 50%.

In this study, a mathematical model for the supersonic condensate flow of natural gas to understand its condensation process in a supersonic separator has been proposed. The effects of export back pressure, inlet temperature, and inlet pressure on the condensation parameters were investigated. The results indicate that the condensation position moves forward with the increase in the inlet pressure and the decrease in the inlet temperature. A method for determining the optimal range of operating parameters (export back pressure, inlet temperature, and inlet pressure) for the supersonic separator is proposed. Within the optimal back pressure range, the region of extreme Mach number in the device should be at the inlet of the straight pipe section after the separation gap, and extreme value distribution areas of low temperature, condensation nucleation, and humidity should be between the nozzle expansion section and the inlet of the straight pipe section. It is important to choose a highe... [more]