Natural Gas Systems Research Articles

Natural hydrogen in the volcanic-bearing sedimentary basin: Origin, conversion, and production rates.

The origins of natural hydrogen in natural gas systems of sedimentary basins and the capacity of these systems to store hydrogen remain inadequately understood, posing crucial questions for the large-scale exploration of natural hydrogen. This study reports on the natural gas composition, stable carbon and hydrogen isotopic values, and helium isotopic values of gas samples collected from the Qingshen gas deposit within volcanic rocks of the Songliao Basin. Natural hydrogen primarily originates from water radiolysis, water-rock interactions (WRI), and mantle. The Qingshen gas deposit contains 95.23 × 109 cubic meters of abiotic CH4, of which 15.24 × 109 cubic meters was generated through hydrogen conversion via Fischer-Tropsch synthesis, with the maximum original hydrogen reserves calculated to be approximately 61.9 × 109 cubic meters. We estimated that the study area has generated a maximum total of 572 × 109 cubic meters of radiolytic hydrogen, 248 × 109 cubic meters of WRI hydrogen, and 127 × 109 cubic meters of mantle-derived hydrogen.

A Novel Stochastic Volt/VAR/Pressure Optimization-Based Conservation Voltage Reduction Technique in Integrated Electricity and Natural Gas Systems with PV Smart Inverters

A Novel Stochastic Volt/VAR/Pressure Optimization-Based Conservation Voltage Reduction Technique in Integrated Electricity and Natural Gas Systems with PV Smart Inverters

Integrating climate and physical constraints into assessments of net capture from direct air capture facilities

Limiting climate change to targets enshrined in the Paris Agreement will require both deep decarbonization of the energy system and the deployment of carbon dioxide removal at potentially large scale (gigatons of annual removal). Nations are pursuing direct air capture to compensate for inertia in the expansion of low-carbon energy systems, decarbonize hard-to-abate sectors, and address legacy emissions. Global assessments of this technology have failed to integrate factors that affect net capture and removal cost, including ambient conditions like temperature and humidity, as well as emission factors of electricity and natural gas systems. We present an integrated assessment of the global deployment potential of this technology. Employing a chemical process model, climate data, grid emission factors, and fugitive methane emission factors, we predict critical performance metrics, including carbon dioxide capture rates, and water-, energy-, and emissions-intensity of capture. Our results support investors and policy makers as they site facilities and develop credible policy instruments to support expansion.

Risk‐Averse Distributionally Robust Environmental‐Economic Dispatch Strategy Based on Renewable Energy Operation: A New Improved Whale Optimization Algorithm

Although the use of optimization techniques for environmental and economic dispatch of integrated electricity and natural gas systems has been widely applied, there are still significant challenges in meeting the multiple energy demands of conventional and renewable energy sources, mainly wind‐solar. In this study, Wasserstein distance is introduced to measure the randomness of wind‐solar power generation to construct the uncertainty set. A multi‐objective distributionally robust optimization (MODRO) environmental‐economic scheduling model for risk aversion that minimizes the risk cost, the system operation cost, and the carbon emission cost is proposed to achieve the balance between the risk cost, the operation cost, and the pollutant emission. To solve the model efficiently, the multi‐objective whale optimization algorithm (IMOWOA) was improved and used the 4‐node power system and the 7‐node natural gas system as case studies. The results show that the MODRO environmental‐economic scheduling model can measure the operational risk due to the stochastic fluctuation of wind‐solar energy sources, and provide an effective decision‐making tool for policymakers. Considering P2G technology and gas turbines at the same time, it promotes the coupled operation of electric‐gas integrated systems and achieves good economic efficiency. Thus, the model provides an effective solution for the stability, economy, and cleanliness of the integrated electric gas system. © 2024 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Methane Gas Sensor using Graphene Nanoflakes at Room Operating Temperature

Methane gas is commonly produced and used in various industries, including agriculture, coal mining, manure management, landfills, natural gas, and petroleum systems. This gas is colorless and odorless. High concentrations of methane gas can have detrimental effects on human health, such as causing headaches, visual issues, and memory loss. Moreover, prolonged exposure to higher concentrations may lead to respiratory and heart rate fluctuations, balance problems, and even unconsciousness. In order to address these concerns, a thick film gas sensor based on graphene nanoflakes is proposed in this work to detect different levels of methane gas at room operating temperature. The gas sensor was fabricated using screen-printing technology on a Kapton film. Graphene nanoflakes were mixed with a binder to create the sensing film. Scanning electron microscopy (SEM) was used to characterize the morphology and X-ray diffraction (XRD) for structural components of the sensing film. Two graphene gas sensors (PF-1 and PF-2) were fabricated using screen-printing to compare their performance to methane at room operating temperature with gas concentrations ranging from 300 to 1000 ppm. The results showed that both gas sensors responded robustly to changing concentrations of methane gas at room operating temperature within 20 s. PF-2 outperforms PF-1, with the result of sensitivity being approximately 0.0000353, 0.0000288, and 0.0000262 for the first, second, and third exposures to methane gas. Both gas sensors also exhibited excellent repeatability characteristics with similar patterns each time exposed to the methane.

Multi-pass Cavity-Enhanced Raman Spectroscopy of Complex Natural Gas Components

BackgroundThe concentration of natural gas components significantly impacts the transportation, storage, and utilization of natural gas. Consequently, implementing online monitoring and leak detection systems is vital to guarantee the efficient use of natural gas and to uphold its safe and stable operation. Raman spectroscopy offers distinctive benefits, including high selectivity, superior precision, and the capability to detect multiple gas components simultaneously using a single-wavelength laser. Nevertheless, the inherent weakness of the Raman effect in gases results in limited detection sensitivity for Raman spectroscopy, which may not suffice for specific practical applications. ResultsThis paper presents a study investigating the detection of natural gas's complex components using a high-sensitivity multi-cavity enhanced Raman spectroscopy technique. An enhanced folded Z-shaped multi-pass cavity has been constructed to amplify the interaction length between the laser and the gas, thereby significantly boosting the Raman signal intensity by 1000 times. The detection limits for CH4, C2H6, C3H8, n-C4H10, i-C4H10, n-C5H12, i-C5H12, and n-C6H14 gases reached 0.12, 0.53, 0.55, 0.67, 0.28, 0.46, 0.34, and 0.71 ppm, respectively. The least squares method was utilized to establish quantitative relationships between the characteristic peak heights and the concentrations of gases, encompassing both single-component and mixed multi-component systems. Additionally, the natural gas samples were configured and subsequently detected and analyzed. SignificanceAs proposed in this paper, the results indicate that the MPC-CERS system boasts several advantages, including a low detection limit, high quantitative accuracy, excellent detection repeatability, and robust system stability. Furthermore, its capability for real-time monitoring is well-suited to meet the gas detection requirements in practical applications. Consequently, the research presented in this paper offers innovative insights for the online tracking and leak detection of distributed energy natural gas systems.

Static voltage stability analysis of integrated smart energy systems

The analysis of multi-energy flows forms the cornerstone for the study of state estimation, safety assessment, and optimization in integrated smart energy systems (ISES). The interactions between various energy flows and the inherent variability of renewable energy sources often lead to significant challenges to the static stability of ISES. This paper investigates the static voltage stability of ISES under multi-energy coupling conditions through multi-energy flow analysis in electric-gas-thermal energy systems. First, a steady-state model of the ISES is constructed by representing the interconnected energy subsystems as equivalent sources and loads in the power grid. Subsequently, through the coupling elements of ISES, the power flows of the natural gas system (NGS) and the district heating system (DHS) are converted into active power in the electrical power system (EPS), resulting in an equivalent power flow equation for the ISES. Then, using Brouwer’s fixed-point theorem, the analytical sufficient conditions for solving the equivalent power flow equation are derived. Finally, a simulation model based on MATLAB/Simulink is established. The steady-state criterion for ISES is obtained in this paper, and the correctness and effectiveness of the proposed conclusions are verified by the simulation results.

An optimization dispatching strategy for integrated electricity and natural gas systems with fast charging stations

With the increasing number of electric vehicles (EVs), a large amount of charging load will affect the safety and economic operation of the distribution network (DN). In this paper, an optimization dispatching strategy for integrated electricity and natural gas systems (IEGS) with fast charging stations (FCSs) is proposed to address the impact of fast charging loads. Firstly, the FCS load model is established based on the simulation of vehicle traveling and vehicle charging. Secondly, a natural gas supply model is established, which includes constraints such as the adjustment range, direction, and total number of supply flow adjustments. Then, an optimization dispatching strategy for IEGS based on energy storage and gas storage is proposed. Finally, the effectiveness of the proposed strategy is verified. The simulation results show that when the proposed strategy is applied, the voltage of FCS node will be stabilized within a good range. And the energy purchase cost will be reduced by more than 50%. The proposed method improves the carrying capacity of DN for FCSs.

Clumped isotopes constrain thermogenic and secondary microbial methane origins in coal bed methane

Methane is an economic energy resource and potent greenhouse gas. Distinguishing secondary microbial methane from thermogenic gas is important for natural gas exploration and consideration of subsurface microbial activity in the global carbon cycle, but remains challenging. To understand controls on methane origins in natural gas systems, we investigated the methane clumped isotopologue distributions in the Qinshui Basin high-thermal maturity coal bed methane (CBM) reservoir. Here, near-equilibrium clumped isotopologues distribution (Δ13CH3D and Δ12CH2D2) inferred a temperature interval of 21.6–252.3 °C. The high-temperature thermodynamic equilibrium most likely represents original thermogenic CBM characteristics during coalification. The low-temperature equilibrium clumped isotopologue distributions suggest microbial alteration to CH4 isotopic bond ordering by increased enzymatically catalyzed isotopic exchange. The independent constraints from clumped isotopes, integrated with other geochemical and genomic evidence, confirm notable secondary microbial methane from biodegradation in the highly mature reservoir. Thus, methane clumped isotopes can be used as unequivocal tracers to distinguish secondary microbial methane from thermogenic gases and hence provide the ability to incorporate them separately into global methane budgets.

Study on the Evolutionary Process and Balancing Mechanism of Net Load in Renewable Energy Power Systems

With the rapid development of renewable energy sources such as wind and solar, the net load characteristics of power systems have undergone fundamental changes. This paper defines quantitative analysis indicators for net load characteristics and examines how these characteristics evolve as the proportion of wind and solar energy increases. By identifying inflection points in the system’s adjustment capabilities, we categorize power systems into low, medium, and high renewable energy penetration. We then establish adjustment models that incorporate traditional coal power, hydropower, natural gas generation, adjustable loads, system interconnections, pumped-storage hydroelectricity, and new energy storage technologies. A genetic algorithm is employed to optimize and balance the net load curves under varying renewable energy proportions, analyzing the mechanism behind net load balance. A case study, based on real operational data from 2023 for a provincial power grid in western China, which is rich in renewable resources, conducts a quantitative analysis of the system’s adjustment capability inflection point and net load balancing strategies. The results demonstrate that the proposed method effectively captures the evolution of the system’s net load and reveals the mechanisms of net load balancing under different renewable energy penetration levels.

Impacts of Natural Gas Pipeline Congestion on the Integrated Gas–Electricity Market in Peru

This paper investigates the impact of natural gas pipeline congestion on the integrated gas–electricity market in Peru, focusing on short-term market dynamics. By simulating congestion by reducing the primary natural gas pipeline’s capacity, the study reveals significant patterns in production costs and load flows within the electrical network. The research highlights the critical interdependencies between natural gas and electricity systems, emphasizing how constraints in one network can directly affect the other. The findings underscore the importance of coordinated management of these interconnected systems to optimize economic dispatch and ensure the reliability of both gas and electricity grids. The study also proposes strategic public policy interventions to mitigate the financial and physical impacts of pipeline congestion, contributing to more efficient and resilient energy market operations.

Probabilistic co‐expansion planning for natural gas and electricity energy systems with wind curtailment mitigation considering uncertainties

AbstractIn response to growing reliance on electricity and gas systems, this paper introduces a stochastic bi‐level model for the optimized integration of these systems. This integration is achieved through sizing and allocating of power‐to‐gas (P2G) and gas‐to‐power (G2P) units. The first level of the model focuses on decisions related to P2G and G2P unit installations, while the second level addresses optimal system operation considering decisions made from first level and stochastic scenarios. The primary aim is to enhance energy‐sharing capabilities through coupling devices and mitigate wind generation curtailment. An economic evaluation assesses the model's effectiveness in reducing costs. N − 1 contingency analysis gauges the integrated system's ability to supply load under emergency conditions. Two new indices, performance of the electricity system and performance of the natural gas system, are proposed for N − 1 contingency analysis. These indices quantify the proportion of the supplied load to the total load, thereby illustrating the system's capacity to meet demand. For numerical investigation, the proposed model is applied to a modified IEEE 14‐bus power system and a 10‐node natural gas system. Numerical results demonstrate a 9.426% reduction in investment costs and a significant 10.6% reduction in wind curtailment costs through proposed planning model.

Decarbonizing natural gas infrastructure: blending hydrogen for sustainable energy

Abstract The paper explores the potential of hydrogen as a clean energy carrier and its integration into existing natural gas systems to reduce carbon intensity. It highlights the need for infrastructure impact studies and significant investment to realize the vision of green hydrogen. It also discusses the properties of hydrogen compared to natural gas, its production methods, and the potential for blending hydrogen into existing natural gas pipelines. Additionally, it provides insights into Egypt’s energy sector and its efforts to embrace renewable energy. It concludes by summarizing notable studies and projects related to hydrogen-natural gas blending. The blending of hydrogen into natural gas systems is an important and achievable first step towards full conversion to 100% hydrogen. The paper presents a compilation of hydrogen blending projects from different countries, showcasing the collaborative efforts and advancements in integrating hydrogen into existing energy systems.

A robust must‐run capacity identifying approach in power system dispatch considering interdependence with natural gas system

AbstractIdentifying the must‐run capacity (MRC) could help to accelerate the unit commitment and assess market power, thus critical for achieving an efficient power system dispatch. However, the existing approaches identify the MRC without considering the ever‐strengthening interdependence between power system and natural gas (NG) system, as well as neglecting either the uncertainties of renewables or the constraints on start‐up/shut‐down states for thermal units. To fill the gaps, this article proposes a novel model and methodology for identifying the MRC in power system considering the interdependence with NG system, with adopting a distributionally robust (DR) approach to consider the uncertainties of renewables. A constraint‐generation based algorithm is devised to solve the model, with a relax‐round‐polish based Alternating Direction Method of Multipliers (ADMM) algorithm to address the interaction between the two energy systems. Comparative studies show the effectiveness in MRC assessment over the existing approaches.

A review of challenges with using the natural gas system for hydrogen

AbstractHydrogen, as an energy carrier, is attractive to many stakeholders based on the assumption that the extensive global network of natural gas infrastructure can be repurposed to transport hydrogen as part of a zero‐carbon energy future. Therefore, utility companies and governments are rapidly advancing efforts to pilot blending low‐carbon hydrogen into existing natural gas systems, many with the goal of eventually shifting to pure hydrogen. However, hydrogen has fundamentally different physical and chemical properties to natural gas, with major consequences for safety, energy supply, climate, and cost. We evaluate the suitability of using existing natural gas infrastructure for distribution of hydrogen. We summarize differences between hydrogen and natural gas, assess the latest science and engineering of each component of the natural gas value chain for hydrogen distribution, and discuss proposed solutions for building an effective hydrogen value chain. We find that every value chain component is challenged by reuse. Hydrogen blending can circumvent many challenges but offers only a small reduction in greenhouse gas emissions due to hydrogen's low volumetric energy density. Furthermore, a transition to pure hydrogen is not possible without significant retrofits and replacements. Even if technical and economic barriers are overcome, serious safety and environmental risks remain.

Low-carbon operation of integrated electricity–gas system with hydrogen injection considering hydrogen mixed gas turbine and laddered carbon trading

Green hydrogen produced by the power-to-gas facilities can be blended into the natural gas system, which is a promising way toward a low-carbon energy system. This paper proposes a laddered carbon trading-based operation model for integrated electricity–gas system with hydrogen injection considering the complex combustion properties of hydrogen mixed gas turbine (HMGT). The power-to-hydrogen, hydrogen methanation, and carbon emission processes are combined with the methane reactor and the flexible carbon capture, utilization and storage facility. Then, a HMGT combustion model based on the system thermodynamics and chemical reaction kinetics is introduced. The piecewise linearization technique is adopted to describe the varying hydrogen production efficiency of electrolysis system. Moreover, an energy balance based quasi-steady-state model to deal with the calorific value problem of the gas mixture is proposed and solved by an advanced sequential cone programming algorithm. Case studies are carried on a 30-bus-20-node system and a 197-bus-171-node practical system in Northwest China to illustrate the effectiveness of the proposed model.

Review and prospect on the construction method of security region for integrated natural gas and power systems

Natural gas and power systems are both important components of modern energy systems. As an efficient and clean peak-shaving power source, natural gas power generation is crucial for ensuring the safe operation of a high-penetration renewable energy power system —supporting China's strategic goal of "carbon peaking and carbon neutrality." However, in recent years, there have been frequent incidents of cascading faults between the gas and power grids. Studying the security region of the integrated electricity-gas system (IEGS) and identifying the system's security margin online is the key to actively preventing such accidents. In view of this, this paper first introduced the typical coupling forms of electricity-gas networks and summarizes the security analysis and evaluation methods from the perspectives of power systems and natural gas systems, respectively. Then, the basic model of the IEGS security region considering the interconnection of gas and electricity networks was extracted, and various methods for solving IEGS security boundaries and dealing with uncertain disturbance factors were compared. Finally, the possible development directions of the construction method of the security region for IEGS were proposed.

The burden of natural gas leaks on public sector emergency response in the United States

Fire departments play a critical role in responding to potential hazards generated by natural gas and propane leaks, yet the costs of providing these services is unknown. Here, we analyzed 15 years of gas leak-coded incidents from the National Fire Incident Reporting System (NFIRS) and estimated associated costs using fire department operating budgets. From 2003 to 2018, a total of 2.4 million gas leak-coded incidents required fire department responses, accounting for ∼0.8% of all nationwide incidents. Reported gas leak incidents have steadily increased nationwide, nearly quadrupling from 2003 to 2018. In 2018, New York City (NYC) experienced 22,090 gas leak incidents—more than the next 25 cities combined—conservatively costing NYC $70 million annually. With a median national response cost of $2609 (S.D. $1734), uncombusted gas leaks conservatively cost U.S. fire departments $564 million in 2018—at least 10x greater than for gas leak-caused fires. City-level natural gas systems entail an underappreciated and increasing public cost burden on emergency response services. Findings herein raise the salience of gas leak-associated emergency response costs and support improved gas leak response coordination between emergency services and gas utility providers. Decision-makers are encouraged to incorporate these costs into cost-benefit analyses and consider the intended and unintended effects on emergency response systems in managing energy transitions.

Epitaxial Metal-Organic Framework-Mediated Electron Relay for H2 Detection on Demand.

Hydrogen is regarded as one of the most promising clean substitutes for fossil fuels toward a carbon-zero society. However, the safety management of the upcoming hydrogen energy infrastructure has not been fully prepared, in contrast to the well-established natural gas and gasoline systems. On the frontline is the guard post of hydrogen detectors, which need to be deployed on various structural surfaces and environmental conditions. Conventional hydrogen detectors are usually bulky and environmentally sensitive, limiting their flexible and conformal deployment to various locations, such as pipelines and valves. Herein, we demonstrate the successful synthesis of a palladium-modified epitaxial metal-organic framework (MOF) on single-layer graphene to fabricate a heterostructure material (Epi-MOF-Pd). Device based on the heterostructure demonstrates high sensitivity toward low- concentration H2 (155% resistance response to 1% H2 within 12 s, a theoretical detection limit of 3 ppm). The 25 nm epitaxial MOF acquires electrons from the Pd nanoparticles after the trace amount of H2 is chemically adsorbed and further relays the electrons to the highly conductive graphene. The Epi-MOF-Pd is both flexible and enduring, and maintains stable detection over 10 000 bending cycles. Through photolithography, device arrays with a density of 3000 units/cm2 are successfully fabricated. This versatile material provides a prospective avenue for the mass production of high-performance chemical-sensitive electronics, which could significantly improve the hydrogen safety management on demand.

Optimization of Interconnected Natural Gas and Power Systems Using Mathematical Programs with Complementarity Constraints

The demand for thermal power generation from natural gas has increased globally due to its cleaner burning properties compared to other fossil fuels. Optimizing the gas flow through the network to meet this demand is challenging due to the nonconvex Weymouth equation constraining gas flow and nodal pressures in pipelines. Traditional methods for addressing this nonconvexity lead to significant approximation errors or high operational costs. This study poses the Weymouth constraint as a Mathematical Programming with Complementarity Constraints (MPCC) for an optimal gas flow problem. The complementarity constraints reformulate the discontinuous sign function using binary-behaving continuous variables. This MPCC-based approach avoids solving mixed-integer programming problems while enhancing the accuracy of conventional linear and second-order approximations. Testing the approach on various interconnected systems, including Colombia’s national gas transportation grid, demonstrated significant reductions in Weymouth approximation errors, thereby supporting effective optimization for interconnected networks.