Search Results (18)

The petroleum industry faces crucial environmental problems that exacerbate business instability, such as climate change and greenhouse gas emission regulations. Generally, governments focus on pricing, environmental protection, and supply security when developing energy policy. This article evaluates the technical efficiency of 53 oil and gas companies in the United States during the period 1998–2018 using the stochastic frontier analysis methods and investigates the degree to which energy policies influence the efficiency levels in these companies. Our empirical results show that the average technical efficiency of the 53 U.S. oil and gas companies is 0.75 and confirm that prices, production, consumption, and reserves of the U.S. petroleum and gas have a significant influence on technical efficiency levels. Specifically, our findings show that renewable energy and nuclear power contribute to explaining the distortion between the optimal and observed output of the U.S. oil and gas companies. Full article

Oil and gas construction projects are of great importance to support and facilitate the process of operation and production. However, these projects usually face chronic risks that lead to time overrun, cost overrun, and poor quality, affecting the projects’ success. Hence, this study focused on identifying, classifying, and modeling the risk factors that have negative effects on the success of construction projects in Yemen. The data were collected through a structured questionnaire. Statistical analysis, relative important index method, and probability impact matrix analysis were carried out to classify and rank the risk factors. The partial least squares path modeling or partial least squares structural equation modeling (PLS-PM, PLS-SEM) is a method for structural equation modeling that allows an estimation of complex cause–effect relationships in path models with latent variables. PLS-SEM was employed to analyze data collected from a questionnaire survey of 314 participants comprising the clients, contractors, and consultants working in oil and gas construction projects. The results showed that the goodness of fit index of the model is 0.638. The developed model was deemed to fit because the analysis result of the coefficient of determination test (R²) of the model was 0.720, which indicates the significant explanation of the developed model for the relationship between the causes of risks and their effects on the success of projects. The most impacted internal risk categories include project management, feasibility study design, and resource material availability. The main external risk elements include political, economic, and security considerations. The created risk factor model explained the influence of risk factors on the success of construction projects effectively, according to statistical and expert validation tests. Full article

A rigorous theoretical investigation has been made on the nonlinear propagation of dust-ion-acoustic shock waves in a multi-component magnetized pair-ion plasma (PIP) having inertial warm positive and negative ions, inertialess non-thermal electrons and positrons, and static negatively charged massive dust grains. The Burgers’ equation is derived by employing the reductive perturbation method. The plasma model supports both positive and negative shock structures in the presence of static negatively charged massive dust grains. It is found that the steepness of both positive and negative shock profiles declines with the increase of ion kinematic viscosity without affecting the height, and the increment of negative (positive) ion mass in the PIP system declines (enhances) the amplitude of the shock profile. It is also observed that the increase in oblique angle raises the height of the positive shock profile, and the height of the positive shock wave increases with the number density of positron. The applications of the findings from the present investigation are briefly discussed. Full article

Enhanced coal bed methane recovery using gas injection can provide increased methane extraction depending on the characteristics of the coal and the gas that is used. Accurate prediction of the extent of gas adsorption by coal are therefore important. Both experimental methods and modeling have been used to assess gas adsorption and its effects, including volumetric and gravimetric techniques, as well as the Ono–Kondo model and other numerical simulations. Thermodynamic parameters may be used to model adsorption on coal surfaces while adsorption isotherms can be used to predict adsorption on coal pores. In addition, density functional theory and grand canonical Monte Carlo methods may be employed. Complementary analytical techniques include Fourier transform infrared, Raman spectroscopy, XR diffraction, and ¹³C nuclear magnetic resonance spectroscopy. This review summarizes the cutting-edge research concerning the adsorption of CO₂, N_2, or mixture gas onto coal surfaces and into coal pores based on both experimental studies and simulations. Full article

Decarbonization of the heating sector is essential to meet the ambitious goals of the Paris Climate Agreement for 2050. However, poorly insulated buildings and industrial processes with high and intermittent heating demand will still require traditional boilers that burn fuel to avoid excessive burden on electrical networks. Therefore, it is important to assess the impact of residential, commercial, and industrial heat decarbonization strategies on the distribution and transmission gas networks. Using building energy models in EnergyPlus, the progressive decarbonization of gas-fueled heating was investigated by increasing insulation in buildings and increasing the efficiency of gas boilers. Industrial heat decarbonization was evaluated through a progressive move to lower-carbon fuel sources using MATLAB. The results indicated a maximum decrease of 19.9% in natural gas utilization due to the buildings’ thermal retrofits. This, coupled with a move toward the electrification of heat, will reduce volumes of gas being transported through the distribution gas network. However, the decarbonization of the industrial heat demand with hydrogen could result in up to a 380% increase in volumetric flow rate through the transmission network. A comparison between the decarbonization of domestic heating through gas and electrical heating is also carried out. The results indicated that gas networks can continue to play an essential role in the decarbonized energy systems of the future. Full article

As an alternative to the construction of new infrastructure, repurposing existing natural gas pipelines for hydrogen transportation has been identified as a low-cost strategy for substituting natural gas with hydrogen in the wake of the energy transition. In line with that, a 342 km, 36″ natural gas pipeline was used in this study to simulate some technical implications of delivering the same amount of energy with different blends of natural gas and hydrogen, and with 100% hydrogen. Preliminary findings from the study confirmed that a three-fold increase in volumetric flow rate would be required of hydrogen to deliver an equivalent amount of energy as natural gas. The effects of flowing hydrogen at this rate in an existing natural gas pipeline on two flow parameters (the compressibility factor and the velocity gradient) which are crucial to the safety of the pipeline were investigated. The compressibility factor behaviour revealed the presence of a wide range of values as the proportions of hydrogen and natural gas in the blends changed, signifying disparate flow behaviours and consequent varying flow challenges. The velocity profiles showed that hydrogen can be transported in natural gas pipelines via blending with natural gas by up to 40% of hydrogen in the blend without exceeding the erosional velocity limits of the pipeline. However, when the proportion of hydrogen reached 60%, the erosional velocity limit was reached at 290 km, so that beyond this distance, the pipeline would be subject to internal erosion. The use of compressor stations was shown to be effective in remedying this challenge. This study provides more insights into the volumetric and safety considerations of adopting existing natural gas pipelines for the transportation of hydrogen and blends of hydrogen and natural gas. Full article

A generalized plasma model with inertial warm ions, inertialess iso-thermal electrons, super-thermal electrons and positrons is considered to theoretically investigate the modulational instability (MI) of ion-acoustic waves (IAWs). A standard nonlinear Schrödinger equation is derived by applying the reductive perturbation method. It is observed that the stable domain of the IAWs decreases with ion temperature but increases with electron temperature. It is also found that the stable domain increases by increasing (decreasing) the electron (ion) number density. The present results will be useful in understanding the conditions for MI of IAWs which are relevant to both space and laboratory plasmas. Full article

Rapidly increasing solid waste generation and energy demand are two critical issues of the current century. Plasma gasification, a type of waste-to-energy (WtE) technology, has the potential to produce clean energy from waste and safely destroy hazardous waste. Among plasma gasification technologies, microwave (MW)-driven plasma offers numerous potential advantages to be scaled as a leading WtE technology if its processes are well understood and optimized. This paper reviews studies on modeling experimental microwave-induced plasma gasification systems. The system characterization requires developing mathematical models to describe the multiphysics phenomena within the reactor. The injection of plasma-forming gases and carrier gases, the rate of the waste stream, and the operational power heavily influence the initiation of various chemical reactions that produce syngas. The type and kinetics of the chemical reactions taking place are primarily influenced by either the turbulence or temperature. Navier–Stokes equations are used to describe the mass, momentum, and energy transfer, and the k-epsilon model is often used to describe the turbulence within the reactor. Computational fluid dynamics software offers the ability to solve these multiphysics mathematical models efficiently and accurately. Full article

Ground-level ozone is a secondary air pollutant that is formed by chemical reactions between precursors, including nitrogen oxides (NO_x) and hydrocarbon (HC). Highway traffic, which can be controlled by traffic operational strategies, is one of the main sources of atmospheric NO_x and HC. Managed-lane pricing is one of the popularly used freeway traffic management approaches, while its impacts on ground-level ozone-related vehicle emissions is, however, still unclear. This motivated the purpose of this research. A case study in Houston, USA indicates that, vehicles on managed lanes had fewer hard accelerations/decelerations and higher average speed, which resulted in higher per-vehicle emissions in grams/hour, while the total emissions of a vehicle were roughly comparable to what they would be on a general-purpose lane. Total daily NO_x and HC emissions per managed lane were 31.9%–42.6% of those per general-purpose lane. The weight ratios between HC and NO_x show that, the ground-level ozone formation of this area is hydrocarbon-limited. Full article

The standard nonlinear Schrödinger Equation (NLSE) is one of the elegant equations to find detailed information about the modulational instability criteria of dust-ion-acoustic (DIA) waves and associated DIA rogue waves (DIARWs) in a three-component dusty plasma medium with inertialess super-thermal kappa distributed electrons, and inertial warm positive ions and negative dust grains. It can be seen that the plasma system supports both fast and slow DIA modes under consideration of inertial warm ions along with inertial negatively charged dust grains. It is also found that the modulationally stable parametric regime decreases with $\kappa$. The numerical analysis has also shown that the amplitude of the first and second-order DIARWs decreases with ion temperature. These results are to be considered the cornerstone for explaining the real puzzles in space and laboratory dusty plasmas. Full article

Clean, more responsible energy production in gas turbine power plants is a challenge. Interestingly, various alternative sources could be found in agricultural locations with great potential of being transformed from agricultural waste to energy. Corn cob gasification gas could be successfully implemented in gas turbines through co-firing with natural gas. Concurrently, agricultural biogas could also be employed for such a purpose. The technology could be implemented in locations such as Vojvodina, Serbia, which is an agricultural region with great potential for producing biogas from agricultural waste. Therefore, this paper approaches the practical implementation of gas produced by adiabatic corn digestion with CO₂ recirculation. Five different cases were assessed. The results are compared to previous analyses that used co-firing of the corn cob gasification gas in representative gas turbine systems. Impacts of the fuel composition on the characteristics of combustion were analyzed using CHEMKIN PRO with GRI–Mech 3.0. Impacts of fuel quality on the power plant performance were analyzed through calculations with a numerical model based on a Brayton cycle of 3.9 MW power output. The application shows acceptable values during co-firing with natural gas without modification of the overall system, with better outlet parameters compared to pure corn gasification gas. Full article

Time mismatch between renewable energy production and consumption, grid congestion issues, and consequent production curtailment lead to the need for energy storage systems to allow for a greater renewable energy sources share in future energy scenarios. A power-to-liquefied synthetic natural gas system can be used to convert renewable energy surplus into fuel for heavy duty vehicles, coupling the electric and transportation sectors. The investigated system originates from power-to-gas technology, based on water electrolysis and CO₂ methanation to produce a methane rich mixture containing H₂, coupled with a low temperature gas upgrading section to meet the liquefied natural gas requirements. The process uses direct air CO₂ capture to feed the methanation section; mol sieve dehydration and cryogenic distillation are implemented to produce a liquefied natural gas quality mixture. The utilization of this fuel in heavy duty vehicles can reduce greenhouse gases emissions if compared with diesel and natural gas, supporting the growth of renewable fuel consumption in an existing market. Here, the application of power-to-liquefied synthetic natural gas systems is investigated at a national level for Italy by 2040, assessing the number of plants to be installed in order to convert the curtailed energy, synthetic fuel production, and consequent avoided greenhouse gases emissions through well-to-wheel analysis. Finally, plant investment cost is preliminarily investigated. Full article

Natural gas plays an important role in energy supply, and its fields of application are diverse. However, the world’s largest growth potential among fossil fuels is attributed to liquefied natural gas (LNG). In the last few years, the U.S. rapidly increased LNG exports, and it is expected that they will further increase the liquefaction capacities. The cost of the LNG value chain is composed of the natural gas price in the country of origin, and the LNG process costs for liquefaction, transportation, storage, and regasification. Thus, the Henry Hub (HH) price in the U.S. is important for U.S. LNG exports to Western Europe. In this paper, gas flows in Western Europe at the beginning of the 2030s are analyzed if the price at HH is higher or lower than expected. Furthermore, the effect of the HH price on monthly U.S. LNG exports are studied. For the calculations, the global gas market model WEGA is used. The results reveal that the price at HH has a significant effect on annual gas flows in Western Europe and also on U.S. LNG exports during the summer. Furthermore, it is shown that pipeline gas in Western Europe will absorb fluctuations of U.S. LNG exports between the presented scenarios. Full article

CO₂ convective mixing in water has been visualized in Hele-Shaw and PVT cell experiments but not at the pore scale. Furthermore, CO₂ convective mixing in a three-phase system (i.e., CO₂ in the presence of both water and oil) has not been visually investigated. A vertically placed micromodel setup was used to visualize CO₂ convective mixing at 100 bar and 50 °C, representative of reservoir conditions. To the best of our knowledge, for the first time, we have visually investigated CO₂ convective mixing in water at the pore scale and also CO₂ convective mixing in a multiphase system (water and oil). CO₂ mixing in water governed by both diffusion and convection mechanisms was observed. The vertical CO₂ transport velocity was calculated to be 0.3 mm/min in both a 100% water saturation system and a residual oil-saturated system. First, CO₂ always found the easiest path through the connected pores, and then CO₂ was transported into less connected pores and dead-end pores. CO₂ transport into dead-end pores was slower than through the preferential path. CO₂ transport into water-filled ganglia with trapped oil was observed and was slower than in water. Full article