Natural Gas Operation Research Articles

Thermo-Economic Assessment and Uncertainty Quantification of Hydrofluoroolefin-Based Single Mixed Refrigerant Process for Natural Gas Liquefaction

Among Floating liquefied natural gas (FLNG) operations, natural gas liquefaction is the most energy intensive. Hence, to achieve energy-efficient and eco-friendly FLNG operations that can meet offshore environment requirements, a hydrofluoroolefin-based single mixed refrigerant (SMR) natural gas (NG) liquefaction process is proposed. The proposed process is optimized using a sine cosine paradigm to reduce the overall energy consumption. Then, the economic performance of the proposed process is performed and analyzed against that of the conventional LNG process. Finally, uncertainty quantification is performed to analyze the process outputs under the effects of uncertain key decision variables to guarantee operational reliability. The optimization yields an energy consumption of 0.2317 kW, resulting in a 41.73% energy saving compared to the conventional SMR process. Moreover, the total annualized cost is reduced to 26.02% owing to the appropriate mixed refrigerant selection and process design. The results of the uncertainty quantification analysis indicate that the flow rates of methane and butane, the evaporation pressure, and the condensation pressure are the most influential factors when processing energy consumption and utilizing the minimum internal temperature approach. This study highlights the importance of introducing eco-friendly refrigerants to replace conventional refrigerants used in NG liquefaction processes.

Investigating large methane enhancements in the U.S. San Juan Basin

In 2014, a satellite-based map of regional anomalies of atmospheric methane (CH4) column retrievals singled out the fossil fuel rich San Juan Basin (SJB) as the biggest CH4 regional anomaly (“hot spot”) in the United States. Over a 3-week period in April 2015, we conducted ground and airborne atmospheric measurements to investigate daily wind regimes and CH4 emissions in this region of SW Colorado and NW New Mexico. The SJB, similar to other topographical basins with local sources, experienced elevated surface air pollution under low wind and surface temperature inversion at night and early morning. Survey drives in the basin identified multiple CH4 and ethane (C2H6) sources with distinct C2H6-to-CH4 emission plume ratios for coal bed methane (CBM), natural gas, oil, and coal production operations. Air samples influenced by gas seepage from the Fruitland coal formation outcrop in La Plata County, CO, had enhanced CH4, with no C2-5 light alkane enhancements. In situ fast-response data from seven basin survey flights, all with westerly winds, were used to map and attribute the detected C2H6 and CH4 emission plumes. C2H6-to-CH4 plume enhancement correlation slopes increased from north to south, reflecting the composition of the natural gas and/or CBM extracted in different parts of the basin. Nearly 75% of the total detected CH4 and 85% of the total detected C2H6 hot spot were located in New Mexico. Emissions from CBM and natural gas operations contributed 66% to 75% of the CH4 hot spot. Emissions from oil operations in New Mexico contributed 5% to 6% of the CH4 hot spot and 8% to 14% of the C2H6 hot spot. Seepage from the Fruitland coal outcrop in Colorado contributed at most 8% of the total detected CH4, while gas venting from the San Juan underground coal mine contributed <2%.

Stochastic optimization model for coordinated operation of natural gas and electricity networks

Renewable energy sources will anticipate significantly in the future energy system paradigm due to their low cost of operation and low pollution. Considering the renewable generation (e.g., wind) intermittency, flexible gas-fired power plants will continue to play their essential role as the main linkage of natural gas and electricity networks, and hence coordinated operation of these networks is beneficial. Furthermore, uncertainty is always found in gas demand prediction, electricity demand prediction, and output power of wind generation. Therefore, in this paper, a two-stage stochastic model for operation of natural gas and electricity networks is implemented. In order to model uncertainty in these networks, Monte Carlo simulation is applied to generate scenarios representing the uncertain parameters. Afterwards, a scenario reduction algorithm based on distances between the scenarios is applied. Stochastic and deterministic models for natural gas and electricity networks are optimized and compared considering integrated and iterative operation strategies. Furthermore, the value of flexibility options (i.e., electricity storage systems) in dealing with uncertainty is quantified. A case study is presented based on a high pressure 15-node gas system and the IEEE 24-bus reliability test system to validate the applicability of the proposed approach. The results demonstrate that applying the stochastic model of gas and electricity networks as well as considering integrated operation strategy in the presence of flexibility provides different benefits (e.g., 14% cost savings) and enhances the system reliability in the case of contingency.

Abstract A22: Unconventional natural gas operations and childhood cancer development in a Pennsylvania birth cohort

Abstract Unconventional natural gas development (UNGD) has been rapidly expanding in Pennsylvania since the mid-2000s. The objective was to analyze associations between UNGD exposure during pregnancy and subsequent development of childhood cancer using Pennsylvania birth and cancer registry data. Birth records and childhood cancer registry records that were linked to birth records were obtained through an IRB-approved application process with the Pennsylvania Department of Health. The present analysis included infants born from 2007 to 2015, a period of rapid UNGD expansion in the state. We excluded mothers and their infants living in the most urban areas (i.e., Pittsburgh and Philadelphia), where exposure to many competing pollution sources may confound the analysis. For each mother, an inverse distance weighted (IDW) well count was calculated based on all active wells drilled within a 10-mile radius of the mother’s residence during the one-year period up to the date of birth. Person-years were accumulated for each child from the birth date until either the date of first childhood cancer diagnosis or, for noncases, the end of the study period (December 31, 2016). Cox proportional hazards models were used to investigate associations between IDW well count and hazard ratio (HR) of cancer development among children. There were 812,143 infants born during the study period with complete outcome and covariate data. Of these, there were 859 and 259 children diagnosed with any type of cancer and the most common type, leukemia, respectively. Models were adjusted for infant sex, congenital anomalies, proximity to major roadways, and maternal factors. After adjustment, the hazard ratio of developing any cancer for children born to mothers living in the highest quartile of UNGD exposure was 1.3 (95% confidence interval: 1.0-1.8) compared to the lowest quartile. Childhood leukemia risk was also 1.3 times higher for children born to the most versus least exposed mothers, although the 95% confidence interval was wider (0.8-2.2). In conclusion, children born to mothers living close to UNGD may be at a slightly increased risk for childhood cancer, although the risk is smaller compared to other established risk factors like the presence of a birth defect or older maternal age. As most of the epidemiologic health studies to date have used well density as a surrogate for UNGD exposure, future studies should consider incorporating environmental sampling or personalized monitoring into their exposure assessments. Citation Format: Shaina L. Stacy, Jeanine M. Buchanich, James P. Fabisiak, Linda Robertson, Ravi K. Sharma, Evelyn O. Talbott, Jian-Min Yuan. Unconventional natural gas operations and childhood cancer development in a Pennsylvania birth cohort [abstract]. In: Proceedings of the AACR Special Conference on Environmental Carcinogenesis: Potential Pathway to Cancer Prevention; 2019 Jun 22-24; Charlotte, NC. Philadelphia (PA): AACR; Can Prev Res 2020;13(7 Suppl): Abstract nr A22.

Lime kiln conversion from coke to natural gas operation – an option in direction of sustainable energy

This paper deals with the conversion of coke fired lime kilns to gas and the conclusions drawn from the completed projects. The paper presents (1) the decision process associated with the adoption of the new technology, (2) the necessary steps of the conversion, (3) the experiences and issues which occurred during the first campaign, (4) the impacts on the beet sugar factory (i.e. on the CO2 balance and exhaust gas temperature), (5) the long term impressions and capabilities of several campaigns of operation, (6) the details of available technologies and (7) additional benefits that would justify a conversion from coke to natural gas operation on existing lime kilns. (8) Forecast view to develop systems usable for alternative gaseous fuels (e.g. biogas).

A Method of Optimal Malfunction Management in Urban Natural Gas Transmission and Distribution Systems

Given the increasing number of urban natural gas transmission and distribution systems, it is particularly crucial to optimize the management of natural gas operations, especially when equipment failure or pipeline leakage occurs in the supply system. To meet the needs of customers for natural gas, in this paper, we considered two cases of pipeline rupture leakage and pressure regulation station failure for different supply areas. We combined natural gas supply pipelines, pressure regulating stations and a gasholder station to establish a failure optimization management model and used genetic algorithms and one-dimensional fluid dynamics models for optimization management and proposed the following two solutions: 1. Complete operation strategy: modify both the pressure of the pressure regulating station and the air supply volume of the gasholder station; 2. Partial operation strategy: modify the pressure of the pressure regulating station only, and keep the supply volume of the gasholder station constant. Finally, our model is applied to an urban natural gas transmission and distribution system. Based on the actual results, failure optimization management is proposed according to the location and the type of failure and constructive options are suggested for the operation of natural gas networks.

Investing in flexibility in an integrated planning of natural gas and power systems

The growing interdependencies between natural gas and power systems, driven by gas-fired generators and gas compressors supplied by electricity, necessitates detailed investigation of the interactions between these vectors, particularly in the context of growing penetration of renewable energy sources. In this research, an expansion planning model for integrated natural gas and power systems is proposed. The model investigates optimal investment in flexibility options such as battery storage, demand-side response, and gas-fired generators. The value of these flexibility options is quantified for gas and electricity systems in Great Britain in 2030. The results indicate that the flexibility options could play an important role in meeting the emission targets in the future. However, the investment costs of these options highly impact the future generation mix as well as the type of reinforcements in the natural gas system infrastructure. Through the deployment of the flexibility options up to annual cost savings in planning and operation of natural gas and power systems could be achieved, compared to the case that no flexibility option is considered.

Strategic-Agent Equilibria in the Operation of Natural Gas and Power Markets

We consider strategic gas/power producers and strategic gas/power consumers operating in both gas and power markets. We build a flexible multi-period complementarity model to characterize day-ahead equilibria in those markets. This model is an equilibrium program with equilibrium constraints that characterizes the market behavior of all market agents. Using a realistic case study, we analyze equilibria under perfect and oligopolistic competition. We also analyze equilibria under different levels of information disclosure regarding market outcomes. We study as well equilibria under different ownership schemes: no hybrid agent, some hybrid agents, and only hybrid agents. Finally, we derive policy recommendations for the regulators of both the gas and the power markets.

Dual-Fuel Operation of Biodiesel and Natural Gas in a Model Gas Turbine Combustor

The dual-fuel combustion characteristics of palm biodiesel/methyl esters (PME) and natural gas (NG) in a model gas turbine swirl flame burner are investigated at a thermal power of 9.3 kW. The PME is atomized into a spray, while the gaseous NG is premixed with the main bulk swirling air before entering the combustion chamber. The dual-fuel PME/NG flame structure is similar to the single-fuel PME, where the sooty flame brush is noticeably absent. The PME and PME/NG flames emit higher peak intensity of OH* and CH* radicals as compared to diesel at the same equivalence ratio. Dual-fuel operation results in lower NO but higher CO at ϕ = 0.9 as compared to pure diesel and PME spray flames. The higher CO emission level for dual-fuel is attributed to poor mixing and incomplete combustion as a result of reduced air flow. At a leaner operation of ϕ = 0.65, enhanced turbulence due to higher bulk air flow results in improved mixing, lowering the overall CO but increasing the NO emissions because of the more intense flame core. The study shows that optimization of the multiphase dual-fuel injection system is needed to achieve low emissions in a gas turbine combustor.

Adsorption gas Heat Pump fuelled with hydrogen enriched natural gas blends: the analytical simulation model development and validation

This study deals with the implementation of an analytical model to simulate the energy performance associated to a commercial Gas adsorption Heat Pump, when H2NG (Hydrogen Enriched Natural Gas) blends are used as fuel. In detail, a water source heat pump manufactured by Robur (GAHP-WS) has been used as a reference device for building the simulation model within the MATLAB-Simulink environment. Thereafter, the simulation results have been validated by the experimental campaign, testing on field and in actual operating conditions the heat pump. Specifically, the model has been developed by implementing the WaterAmmonia mass and energy balances for each component. It is able to evaluate fuel consumption, efficiency in terms of GUE, required thermal power from the cold heat sink as well as the water outlet temperature at the evaporator, once the heating load is used as the main input. The experimental campaign for the model calibration and validation has been carried out over the winter season. Additionally, the heat pump performance has been detected when it operates to supply hot water at 60 °C and 55 °C, and it is fuelled with growing hydrogen fractions, starting from 0% vol., 5% vol. up to 10% vol. In the end, the standard errors as well as the relative ones affecting the main output parameters have computed for the validation process. From the outcomes it emerges that the average relative standard error related to all load conditions is lower than 2.5% for natural gas operation. On the contrary, it ranges between 2.5% and 4% when H2NG at 5% and 10% by volume have been burnt.

Decentralized Privacy-Preserving Operation of Multi-Area Integrated Electricity and Natural Gas Systems With Renewable Energy Resources

With the proliferation of natural gas combined cycle units, the modern energy infrastructure has evolved into a coupled electricity and natural gas system, which often encompasses multiple large-scale and geographically-diverse energy areas. The similarity in electricity and natural gas consumption profiles in coupled systems gives rise to critical mandates for the coordinated optimization of electricity and natural gas operation. This paper presents a decentralized optimization framework, which considers wind energy and power-to-gas (P2G) technologies in the operation of integrated multi-area electricity and natural gas transmission system (IEGTS). First, a comprehensive optimal dispatch model is established for the multi-area IEGTS in a centralized manner where bi-directional flows of electricity and natural gas among multi-areas are optimized considering the stochastic nature of wind energy. In particular, a linearized transient-state gas flow model under mild assumptions is proposed to represent the dynamic characteristics of the natural gas sector. The centralized optimization problem is decomposed into a set of computationally-tractable subproblems that are solved independently in individual areas. The alternating direction multiplier method is employed to achieve a rapidly convergent solution while preserving the privacy of operation data shared among participating areas. Finally, case studies are carried out on two multi-area IEGTS with multiple wind generation scenarios which demonstrate the computational performance of the proposed method with P2G facilities operating in variable conditions.

Characterizing anthropogenic methane sources in the Houston and Barnett Shale areas of Texas using the isotopic signature δ13C in CH4

Methane (CH4) is an important greenhouse gas with its mixing ratio increasing in the global atmosphere. Identifying fingerprints of CH4 emissions is critical to understanding potential impacts of various anthropogenic sources in the Greater Houston area (GHA) and extensive natural gas operations in the Barnett Shale area (BSA) of Texas. Stable carbon isotope ratios of CH4 (δ13CCH4) has been proposed to be a useful technique for differentiating individual CH4 sources. Measurements of CH4 mixing ratios and δ13CCH4 were sampled using a mobile laboratory equipped with cavity ring-down spectrometers (CRDS). Areal CH4 distributions and the background δ13CCH4 signature were obtained from filtered ambient signals; −47.0‰ (GHA) and − 48.5‰ (BSA) were calculated. The fingerprint of thirty-three anthropogenic sources in the two study areas were sampled with forty-four δ13C analyses conducted. Repeated measurements indicated the natural variation of δ13CCH4 signatures of individual CH4 sources. An unexpected massive CH4 fugitive leak was detected near the San Jacinto River Fleet site in Houston exhibiting an δ13CCH4 value around −42‰. Our results and findings demonstrate the utility of δ13CCH4for facilitating emission inventories and atmospheric modeling.

Conversion of Diesel Engines to a Gas and Gas–Diesel Cycle

The conversion of diesel engines to gas and gas–diesel cycles during the production process is analyzed. The requirements for conversion to natural-gas operation are presented. The power, efficiency, and environmental impact of diesel engines, natural-gas engines, and gas–diesel engines are compared.

Operation of natural gas and electricity networks with line pack

This paper addresses the coordinated operation of the electricity and natural gas networks considering the line pack flexibility in the natural gas pipelines. The problem is formulated as a mixed integer linear programming problem. The objective is to minimize the operation cost of the electricity and natural gas networks considering the price of the natural gas supply. Benders decomposition is used to solve the formulated problem. The master problem minimizes the startup and shutdown costs as well as the operation cost of the thermal units other than the gas-fired generation units in the electricity network. The first subproblem validates the feasibility of the decisions made in the master problem in the electricity network. And if there is any violation, feasibility Benders cut is generated and added to the master problem. The second subproblem ensures the feasibility of the decisions of the master problem in the natural gas transportation network considering the line pack constraints. The last subproblem ensures the optimality of the natural gas network operation problem considering the demand of the gas-fired generation units and line pack. The nonlinear line pack and flow constraints in the feasibility and optimality subproblems of natural gas transportation network are linearized using Newton-Raphson technique. The presented case study shows the effectiveness of the proposed approach. It is shown that leveraging the stored gas in the natural gas pipelines would further reduce the total operation cost.

A Systematic Review of the Epidemiologic Literature Assessing Health Outcomes in Populations Living near Oil and Natural Gas Operations: Study Quality and Future Recommendations.

A systematic method was used to review the existing epidemiologic literature and determine the state of the scientific evidence for potential adverse health outcomes in populations living near oil and natural gas (ONG) operations in the United States. The review utilized adapted systematic review frameworks from the medical and environmental health fields, such as Grading of Recommendations, Assessment, Development and Evaluations (GRADE), the Navigation Guide, and guidance from the National Toxicology Program’s Office of Health Assessment and Translation (OHAT). The review included 20 epidemiologic studies, with 32 different health outcomes. Studies of populations living near ONG operations provide limited evidence (modest scientific findings that support the outcome, but with significant limitations) of harmful health effects including asthma exacerbations and various self-reported symptoms. Study quality has improved over time and the highest rated studies within this assessment have primarily focused on birth outcomes. Additional high-quality studies are needed to confirm or dispute these correlations.

Experimental Investigation of a Heavy-Duty Compression-Ignition Engine Retrofitted to Natural Gas Spark-Ignition Operation

Heavy-duty compression-ignition (CI) engines converted to natural gas (NG) operation can reduce the dependence on petroleum-based fuels and curtail greenhouse gas emissions. Such an engine was converted to premixed NG spark-ignition (SI) operation through the addition of a gas injector in the intake manifold and of a spark plug in place of the diesel injector. Engine performance and combustion characteristics were investigated at several lean-burn operating conditions that changed fuel composition, spark timing, equivalence ratio, and engine speed. While the engine operation was stable, the reentrant bowl-in-piston (a characteristic of a CI engine) influenced the combustion event such as producing a significant late combustion, particularly for advanced spark timing. This was due to an important fraction of the fuel burning late in the squish region, which affected the end of combustion, the combustion duration, and the cycle-to-cycle variation. However, the lower cycle-to-cycle variation, stable combustion event, and the lack of knocking suggest a successful conversion of conventional diesel engines to NG SI operation using the approach described here.

Long‐Term Measurements Show Little Evidence for Large Increases in Total U.S. Methane Emissions Over the Past Decade

AbstractRecent studies show conflicting estimates of trends in methane (CH4) emissions from oil and natural gas (ONG) operations in the United States. We analyze atmospheric CH4measurements from 20 North American sites in the National Oceanic and Atmospheric Administration Global Greenhouse Gas Reference Network and determined trends for 2006–2015. Using CH4vertical gradients as an indicator of regional surface emissions, we find no significant increase in emissions at most sites and modest increases at three sites heavily influenced by ONG activities. Our estimated increases in North American ONG CH4emissions (on average approximately 3.4 ± 1.4 %/year for 2006–2015, ±σ) are much smaller than estimates from some previous studies and below our detection threshold for total emissions increases at the east coast sites that are sensitive to U.S. outflows. We also find an increasing trend in ethane/methane emission ratios, which has resulted in major overestimation of oil and gas emissions trends in some previous studies.

Coordinated Operation of Electricity and Natural Gas Systems: A Convex Relaxation Approach

The variability in the generation dispatch of the natural gas generation units will lead to fluctuation in natural gas demand profile that could further jeopardize the security of the natural gas network. The coordinated operation of electricity and natural gas infrastructure systems would help to improve the security and reliability measures in both infrastructure systems and mitigate the risk of demand curtailment. The electricity and natural gas network operation problems are non-convex mixed-integer nonlinear programming problems that are hard to solve in polynomial time. The non-convex feasible regions are formed by the Weymouth constraint and the introduced binary commitment decision variables in the natural gas and electricity network operation problems, respectively. This paper utilized a sparse semidefinite programming (SDP) relaxation to procure the optimal solution for the coordinated operation of electricity and natural gas networks. The presented algorithm leverages the sparseness of the natural gas network to construct several small matrices of lifting variables that are used to form a tight and traceable SDP relaxation. A set of valid constraints that tighten the relaxation ensures the exactness of the solution procured from the relaxed problem. The effectiveness of the presented approach is shown in case studies.

A novel protocol for reviving of oil and natural gas wells

For effective cleaning of oil and gas wells and their revival, a novel fluid composition of enzyme-G with acid mixture together with corrosion inhibitor and selected additives is developed. Laboratory and field experiments endorse the effectiveness of the new fluid composition. Upon testing and analyzing the results with various treatment combinations, the procedure is optimized. Its efficacy is validated by treating various oil and natural gas operations. This communication provides a comprehensive description of the method for cleaning the oil and gas wells and their stimulation for improving the production. The novel enzymes-G composition developed, effectively removes the impurities from the face of the wellbore, improve pore formation and create additional artificial channels to enhance the production of oil and gas. The developed protocols could also be used in injection wells to improve the injection rates.

Shale gas transmission and housing prices

In this study, we exploit residential property sales data in New York to value the external environmental costs of the proposed Constitution Pipeline, a high-capacity transmission pipeline designed to transport hydraulically-fractured natural gas in Pennsylvania to large northeastern markets. Results from difference-in-differences models suggest post-announcement price declines of 9% (∼$12,000) for those properties located within three kilometers of the pipeline. These results are strongly robust to different specifications and subsets of the data, as well as falsification testing. Additionally, we find some evidence of attenuation in our treatment effect over time, which is indicative of either declining salience or expectations of the pipeline over time. Our results suggest that homebuyer expectations of the environmental externalities of natural gas pipeline construction and operations are large and negative.