This study explores the international natural gas market integration using the Engle−Granger cointegration and error correction model. Previous studies have suggested that liquefied natural gas (LNG) and oil-linked pricing with a long-term contract have played key roles in gas market integration, especially between European and Asian markets. There is, however, little discussion of the role of the emergence of a swing supplier. A swing supplier, e.g., Qatar or Russia, is flexible to unexpected changes in supply and demand in both European and Asian markets and adapts the gas production/exports swiftly to meet the changes in the markets. Qatar has been a swing supplier since 2005 in the global natural gas market. In 2009, Qatar’s global LNG export share reached above 30% and has remained around 25% since then. Empirical results indirectly support that the emergence of a swing supplier may tighten market integration between Europe and Asia. The swing supplier may have accelerated the deg... [more]

The oil and gas industry generates a significant amount of harmful greenhouse gases that cause irreversible environmental impact; this fact is exacerbated by the world’s utter dependence on fossil fuels as a primary energy source and low-efficiency oil and gas operation plants. Integration of solid oxide fuel cells (SOFCs) into natural gas plants can enhance their operational efficiencies and reduce emissions. However, a systematic analysis of the life cycle impacts of SOFC integration in natural gas operations is necessary to quantitatively and comparatively understand the potential benefits. This study presents a systematic cradle-to-grave life cycle assessment (LCA) based on the ISO 14040 and 14044 standards using a planar anode-supported SOFC with a lifespan of ten years and a functional unit of one MW electricity output. The analysis primarily focused on global warming, acidification, eutrophication, and ozone potentials in addition to human health particulate matter and human tox... [more]

Blockchain technology has emerging areas of deployment in diverse sectors and use cases. In this study, several potential application areas of blockchain with promising benefits have been identified in the natural gas industry. There is no single solution that can address different challenges and meet disparate requirements. Therefore, it is important to understand the needs of the natural gas industry and propose appropriate blockchain solutions. Moreover, in the literature, there is a lack of detailed case studies involving industrial experts from the natural gas sector. Expert opinion can be useful for prioritizing the most needed or expected blockchain application areas among several options. By considering privacy, authentication, speed, security, energy consumption, and costs, suitable blockchain types and consensus mechanisms can be determined. This study presents one of the first detailed case studies for tailored applications of blockchain in the natural gas industry. Through... [more]

Notwithstanding the policies that move towards electrified powertrains, the transportation sector mainly employs internal combustion engines as the primary propulsion system. In this regard, for medium- to heavy-duty applications, as well as for on- and off-road applications, diesel engines are preferred because of the better efficiency, lower CO2, and greater robustness compared to spark-ignition engines. Due to its use at a large scale, the internal combustion engines as a source of energy depletion and pollutant emissions must further improved. In this sense, the adoption of alternative combustion concepts using cleaner fuels than diesel (e.g., natural gas, ethanol and methanol) presents a viable solution for improving the efficiency and emissions of the future powertrains. Particularly, the methane−diesel dual-fuel concept represents a possible solution for compression ignition engines because the use of the low-carbon methane fuel, a main constituent of natural gas, as primary fue... [more]

The nitrogen (N2) expander and single mixed refrigerant (SMR) liquefaction processes are recognized as the most favorable options to produce liquefied natural gas (LNG) at small-scale and offshore sites. These processes have a simple and compact design that make them efficient with respect to their capital costs. Nevertheless, huge operating costs, mainly due to their lower energy efficiency, remains an ongoing issue. Utilization of design variables having non-optimal values is the primary cause for the lower energy efficiency; which, in turn, leads to exergy destruction (i.e., entropy generation), and ultimately the overall energy consumption is increased. The optimal execution of the design variables of LNG processes can be obtained through effective design optimization. However, the complex and highly non-linear interactions between design variables (refrigerant flowrates and operating pressures) and objective function (overall energy consumption) make the design optimization a diff... [more]

South Korea is planning to substitute some residential natural gas (NG), a fossil fuel that relies on imports, with renewable methane (RM) from bio-gas, a renewable energy source. Thus, information about households’ willingness to pay (WTP) for implementing the plan is widely needed. This article, therefore, examines the WTP using an economic approach of contingent valuation (CV). More specifically, 1000 households were asked about the additional WTP for RM over NG through in-person face-to-face surveys across the country, adopting a dichotomous choice question format, during August 2018. As a few interviewees responded zero WTP for various reasons, a spike model that could reflect zero WTP observations was utilized. The household additional WTP for RM over NG was estimated, with statistical significance, as 191.46 Korean won (USD 0.17) per m3 and worth 31.9% of the average price of residential NG. This value means a price premium for RM compared to NG. In other words, this study found... [more]

Underground geological energy and CO2 storage contribute to mitigation of anthropogenic greenhouse-gas emissions and climate change effects. The present study aims to present specific underground energy and CO2 storage sites in Greece. Thermal capacity calculations from twenty-two studied aquifers (4 × 10−4−25 × 10−3 MJ) indicate that those of Mesohellenic Trough (Northwest Greece), Western Thessaloniki basin and Botsara flysch (Northwestern Greece) exhibit the best performance. Heat capacity was investigated in fourteen aquifers (throughout North and South Greece) and three abandoned mines of Central Greece. Results indicate that aquifers present higher average total heat energy values (up to ~6.05 × 106 MWh(th)), whereas abandoned mines present significantly higher average area heat energy contents (up to ~5.44 × 106 MWh(th)). Estimations indicate that the Sappes, Serres and Komotini aquifers could cover the space heating energy consumption of East Macedonia-Thrace region. Undergroun... [more]

Heat losses caused by the operation of compressor units are a key problem in the energy efficiency improvement of the natural gas compression station operation. Currently, waste heat recovery technologies are expensive and have low efficiency. One of these technologies is organic Rankine cycle (ORC) which is often analyzed in scientific works. In this paper, the authors decided to investigate another technology that allows for the usage of the exhaust waste energy—the supercritical Brayton cycle with CO2 (S-CO2). With a thermodynamic model development of S-CO2, the authors preformed a case study of the potential S-CO2 system at the gas compressor station with the reciprocating engines. By comparing the values of selected S-CO2 efficiency indicators with ORC efficiency indicators at the same natural gas compression station, the authors tried to determine which technology would be better to use at the considered installation. Investigations on parameter change impacts on the system opera... [more]

This paper applies a heuristic approach to optimize the predictor variables in artificial neural networks when forecasting raw material prices for energy production (coking coal, natural gas, crude oil and coal) to achieve a better forecast. Two goals are (1) to determine the optimum number of time-delayed terms or past values forming the lagged variables and (2) to improve the forecast accuracy by adding intrinsic signals to the lagged variables. The conclusions clearly are in opposition to the actual scientific literature: when addressing the lagged variable size, the results do not confirm relationships among their size, representativeness and estimation accuracy. It is also possible to verify an important effect of the results on the lagged variable size. Finally, adding the order in the time series of the lagged variables to form the predictor variables improves the forecast accuracy in most cases.

Using a fresh empirical approach to time-frequency domain frameworks, this study analyzes the return and volatility spillovers from fossil fuel markets (coal, natural gas, and crude oil) to electricity spot and futures markets in Europe. In the time domain, by an approach developed by Diebold and Yilmaz (2012) which can analyze the directional spillover effect across different markets, we find natural gas has the highest return spillover effect on electricity markets followed by coal and oil. We also find that return spillovers increase with the length of the delivery period of electricity futures. In the frequency domain, using the methodology proposed by Barunik and Krehlik (2018) that can decompose the spillover effect into different frequency bands, we find most of the return spillovers from fossil fuels to electricity are produced in the short term while most of the volatility spillovers are generated in the long term. Additionally, dynamic return spillovers have patterns correspo... [more]

Transmission pipelines deliver natural gas to consumers around the world for the production of heat, electricity, and organic chemicals. In the United States, 2.56 million miles (4.12 million km) of pipelines carry natural gas to more than 75 million customers. With the benefits of pipelines come the risks to health and property posed by leaks and explosions. Proposals for new and recommissioned pipelines challenge host communities with uncertainty and difficult decisions about risk management. The appropriate community response depends on the risk level, the potential cost, and the prospect for compensation in the event of an incident. This article provides information on the risks and expected costs of pipeline leaks and explosions in the United States, including the incident rates, risk factors, and magnitude of harm. Although aggregated data on pipeline incidents are available, broadly inclusive data do not serve the needs of communities that must make critical decisions about host... [more]

Decentralized power generation by combined heat and power plants becomes increasingly popular as a measure to advance the energy transition. In this context, a substantial advantage of small combined heat and power plants is based on the relatively low pollutant emissions. However, a large proportion of the pollutant emissions is produced during a cold-start. This fact is not reflected in governmental and institutional emission guidelines, as these strongly focus on the emission levels under steady-state conditions. This study analyzes the spark advance, the reference air/fuel ratio and an electrically heated catalyst in terms of their potential to reduce the cold-start emissions of a micro combined heat and power plant which uses a natural gas fueled reciprocating internal combustion engine as prime mover and a three-way catalytic converter as aftertreatment system. Based on these measures, control approaches were developed that account for the specific operating conditions of the cla... [more]

Propane-Precooled Mixed Refrigerant (C3MR) and Single Mixed Refrigerant (SMR) processes are considered as optimal choices for onshore and offshore natural gas liquefaction, respectively. However, from thermodynamics point of view, these processes are still far away from their maximum achievable energy efficiency due to nonoptimal execution of the design variables. Therefore, Liquefied Natural Gas (LNG) production is considered as one of the energy-intensive cryogenic industries. In this context, this study examines a single-solution-based Vortex Search (VS) approach to find the optimal design variables corresponding to minimal energy consumption for LNG processes, i.e., C3MR and SMR. The LNG processes are simulated using Aspen Hysys and then linked with VS algorithm, which is coded in MATLAB. The results indicated that the SMR process is a potential process for offshore sites that can liquefy natural gas with 16.1% less energy consumption compared with the published base case. Whereas,... [more]

This study measures the connectedness of natural gas and electricity spot returns to their futures returns with different maturities. We employ the Henry Hub and the Pennsylvania, New Jersey, and Maryland (PJM) Western Hub Peak as the natural gas price indicator and the wholesale electricity price indicator, respectively. We also use each commodity’s spot prices and 12 types of futures prices with one to twelve months maturities and realize results in fourfold. First, we observe mutual spillover effects between natural gas futures returns and learn that the natural gas futures market is integrated. Second, we observe the spillover effects from natural gas futures returns to natural gas spot returns (however, the same is not evident for natural gas spot returns to natural gas futures returns). We find that futures markets have better natural gas price discovery capabilities than spot markets. Third, we observe the spillover effects from natural gas spot returns to electricity spot retur... [more]

High-pressure direct-injection (HPDI) natural gas marine engines are widely used because of their higher thermal efficiency and lower emissions. The effects of different injection rate shapes on the combustion and emission characteristics were studied to explore the appropriate gas injection rate shapes for a low-speed HPDI natural gas marine engine. A single-cylinder model was established and the CFD model was validated against experimental data from the literature; then, the combustion and emission characteristics of five different injection rate shapes were analyzed. The results showed that the peak values of in-cylinder pressure and heat release rate profiles of the triangle shape were highest due to the highest maximum injection rate, which occurred in a phase close to the top dead center. The shorter combustion duration of the triangle shape led to higher indicated mean effective pressure (IMEP) and NOx emissions compared with other shapes. The higher initial injection rates of t... [more]

This paper presents a study on the energy efficiency and emissions of a converted high-revolution bore 79.5 mm/stroke 95 mm engine with a conventional fuel injection system for operation with dual fuel feed: diesel (D) and natural gas (NG). The part of NG energy increase in the dual fuel is related to a significant deterioration in energy efficiency ( η i ) , particularly when engine operation is in low load modes and was determined to be below 40% of maximum continuous rating. The effectiveness of the D injection timing optimisation was established in high engine load modes within the range of a co-combustion ratio of NG ≤   0.4: with an increase in η i , compared to D, the emissions of NO x + HC decreased by 15%   to   25%, while those of CO 2 decreased by 8% to16%; the six-fold CO emission increase, up to 6 g/kWh, was unregulated. By referencing the indicated process characteristics of the established... [more]

A throttle can be installed on the intake pipe of a natural gas (NG)/diesel dual-fuel engine to control the excess air ratio of the air-fuel mixture by adjusting the air intake. Building on a previously proposed NG/diesel dual-fuel supply strategy using the adjustment of excess air ratio, this work further studied the effects of different injection timing schemes on output power, fuel efficiency, and pollutant emissions of a dual-fuel engine under low to medium load conditions. In the experiment, the engine was operated at a speed of 1600 r/min, under either low (27.1 N·m) or medium (50.6 N·m) loads, and the NG substitution rate was either 40%, 60%, or 80%. The effect of different injection timing schemes on the combustion performance of the engine under low to medium load conditions was studied based on in-cylinder pressure changes detected by a pressure sensor. Experimental results showed that under medium-speed low-load conditions and a NG substitution rate of 40%, setting the diese... [more]

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.