Natural hydrogen has gained prominence as a potential contributor to the low-carbon energy landscape; however, exploration techniques are still evolving. Current methods primarily rely on dry soil ...gas studies or gas vent measurements. Because gas vents are scarce and groundwater inhibits hydrogen gas flux from the soil, other field detection techniques are necessary. This research paper presents a novel approach for advancing natural hydrogen exploration through the analysis of headspace gas of agitated groundwater extracted from dedicated shallow boreholes to better estimate the hydrogen gas flux and its variations with time. Several shallow boreholes were drilled in Western Australia on the Yilgarn Craton to test the new protocol versus standard gas meter sensing method to detect and quantify hydrogen seepage. While the standard methods could not detect hydrogen because of groundwater occurrence, the new technique was able to detect elevated hydrogen levels from shallow boreholes. These hydrogen concentrations exhibit both temporal and spatial variations, highlighting the complex dynamics of the hydrogen surface seepage. By introducing this innovative technique, we provide a practical and straightforward field tool for subsurface natural hydrogen exploration regardless of water in/around the sensor, thereby facilitating the development of this promising energy resource.
The overall fracturing stimulation effect using quartz sand as a proppant is poor, resulting in no breakthrough in the production of coalbed methane (CBM) wells in the low permeability coal reservoir ...of Lu’an Mining Area. In this study, the mixed coated ceramsite of three particle sizes (40–60, 16–40, and 12–20 mesh) was selected as a proppant to conduct a hydraulic fracturing field experiment on CBM wells, located near the three wells fractured with quartz sand in the study area. The drainage and production effects of mixed particle size-coated ceramsite and quartz sand fractured wells in the area were compared. The results show that the cumulative gas production from the coated ceramsite fractured CBM well was approximately 93,004 m3 in 238 days of gas production, with a maximum daily gas production of 825 m3/d, approximately 3.3 times that of the quartz sand fractured wells. After 400 days of gas production, the two types of proppant-fractured CBM wells differed notably, the daily gas production of the coated ceramsite-fractured well being 450–825 m3/d and that of the quartz sand-fractured wells being only 150–250 m3/d. In the stable production stage, the coated ceramsite-fractured well displayed a better gas production potential. Therefore, in view of the low permeability of the coal reservoir, the use of coated ceramsite to fracture CBM wells can achieve a more satisfactory production enhancement effect. The research findings can provide a reference for fracturing-induced production enhancement of low-permeability reservoirs.
Coal fines are commonly produced in the form of aggregates during the development of coalbed methane (CBM), which significantly restricts the well productivity. Specifically, the reunion state of ...coal fines plays a key role in impacting the conductivity of propping fractures after fracturing. In this work, the anionic surfactant sodium dodecyl benzene sulfonate (SDBS) was selected to control the reunion state of coal fines. Visualized simulations of coal fines’ transport behavior in proppants with different particle sizes were carried out under low constant pressure based on sand pack experiments. Moreover, the characteristics of coal fine filling and production in propping fractures were obtained. The results indicate that SDBS has a dispersion effect on coal fine aggregates in the KCl fracturing fluid, with an average reduction of 36% in particle size. There is a positive correlation between the proppant size and the permeability coefficient of propping fractures. Coal fines reduce the permeability coefficients obviously, which first rapidly decrease and then slowly reach a stable stage. In the first stage, the changes of permeability coefficients are affected by the relative particle sizes of the proppant and the coal fine, which is consistent with the classic 1/3 sealing mechanism. In the second stage, SDBS increases the amount of coal fines between the proppant pore throats, and the thickness of the filter cake formed from coal fines at the entrance of the propping fracture increases, resulting in the inhibition of fracture conductivity. Additionally, the output of coal fines is increased dramatically induced by SDBS. Finally, the inhibitory effect of SDBS on fluid production was verified by comparing the water production and coal fine content of two field wells CW # 1 and CW # 2. This study has guiding significance for the output and control of coal fines in low-pressure production of CBM wells.
•This paper addresses combined heat and power system and energy network expansion planning.•The proposed model considers different scenarios of energy consumption.•The introduced method uses a ...three-level iterative heuristic optimization algorithm.•The proposed method is applied to 9-bus, 33-bus and 123-bus test systems.
This paper addresses a hierarchical framework for the energy resources and network expansion planning of an Energy Distribution Company (EDC) that supplies its downward Active Industrial MicroGrids (AIMGs) with hot water and/or steam and electricity through its district heating and electric grid, respectively. The main contribution of this paper is that the proposed model considers AIMGs’ electricity transactions with each other and/or other customers through the EDC’s electric main grid and investigates the impacts of these transactions on the expansion planning problem. The solution methodology is another contribution of this paper that tries to trade-off between accuracy and computational burden. The proposed framework uses a three-stage iterative heuristic optimization algorithm that considers different uncertainties of the planning and operational parameters. At the first stage, the algorithm determines the characteristics of energy system facilities for different stochastic parameter scenarios. At the second stage, the feasibility and optimality of AIMGs’ electric transactions are evaluated and the optimal scheduling energy resources in normal states are determined. Finally, at the third stage, different demand response alternatives, load shedding and the AIMGs’ electric transaction interruptions for contingent conditions are decided. The proposed method is applied to 9-bus, 33-bus and 123-bus IEEE test systems. Further, a full search algorithm is used to evaluate the quality of solutions of the proposed algorithm. The introduced algorithm reduced the total costs for the 9-bus, 33-bus and 123-bus system about 18.645%, 9.658%, and 4.849% with respect to the costs of custom expansion planning exercises, respectively.
The storage of enormous energies is a significant challenge for electrical generation. Researchers have studied energy storage methods and increased efficiency for many years. In recent years, ...researchers have been exploring new materials and techniques to store more significant amounts of energy more efficiently. In particular, renewable energy sources and electric vehicle technologies are triggering these scientific studies. Scientists and manufacturers recently proposed the supercapacitor (SC) as an alternating or hybrid storage device. This paper aims to provide a comprehensive review of SC applications and their developments. Accordingly, a detailed literature review was first carried out. The historical results of SCs are revealed in this paper. The structure, working principle, and materials of SC are given in detail to be analysed more effectively. The advantages and disadvantages, market profile, and new technologies with manufacturer corporations are investigated to produce a techno-economic analysis of SCs. The electric vehicle, power systems, hybrid energy storage systems with integration of renewable energy sources, and other applications of SCs are investigated in this paper. Additionally, SC modelling design principles with charge and discharge tests are explored. Other components and their price to produce a compact module for high power density are also investigated.
The dynamic tariff (DT) method is designed for the distribution system operator (DSO) to alleviate congestions that might occur in a distribution network with high penetration of distributed energy ...resources (DERs). Uncertainty management is required for the decentralized DT method because the DT is determined based on optimal day-ahead energy planning with forecasted parameters such as day-ahead energy prices and energy needs which might be different from the parameters used by aggregators. The uncertainty management is to quantify and mitigate the risk of the congestion when employing the DT method, which is achieved by firstly formulating the problem as a chance constrained two-level optimization and then solving the problem through an iterative procedure. Two case studies were conducted to demonstrate the efficacy of the uncertainty management of DT method.
In this study a mixed integer linear programming (MILP) model is created for the design (i.e. technology selection, unit sizing, unit location, and distribution network structure) of a distributed ...energy system that meets the electricity and heating demands of a cluster of commercial and residential buildings while minimising annual investment and operating cost. The model is used to analyse the economic and environmental impacts of distributed energy systems at the neighbourhood scale in comparison to conventional centralised energy generation systems. Additionally, the influence of energy subsidies, such as the UK's Renewable Heat Incentives and Feed in Tariffs, is analysed to determine if they have the desired effect of increasing the economic competitiveness of renewable energy systems.
•A MILP model was created to design a distributed energy resource system for a cluster of buildings.•The optimal DER system was found to decrease annual costs by 40% and CO2 emissions by 50%.•Small wind turbines and biomass boilers were found to be the optimal technologies.•Energy subsidies are vital because they increase the affordability of low carbon technologies.
This study aims to investigate the impact of CO2 huff-n-puff after CO2 flooding on recovery efficiency in tight sandstone reservoirs. The experimental methodology involved the selection of three ...representative cores with different permeability levels to emulate class I, II, and III reservoirs. To examine immiscible, nearly miscible, and miscible conditions for different reservoir samples, a physical simulation flow system integrated with nuclear magnetic resonance technology was employed. CO2 flooding was performed followed by CO2 huff-n-puff experiments at five pressures, enabling a quantitative analysis of oil production characteristics in various pores during the flooding and huff-n-puff processes. This study provides insights into the microscopic production characteristics and oil recovery influenced by huff-n-puff in tight sandstone reservoirs subsequent to CO2 flooding. The experimental results highlight that recovery efficiency increases with higher permeability, with class I reservoir samples exhibiting the highest recovery rate at 76.47%, followed by class II reservoirs at 69.33%, and class III reservoirs at 44.43%. Huff-n-puff recovery for class I and class II reservoirs gradually declines with increasing pressure after flooding, whereas class III reservoirs display an opposite trend, with recovery gradually increasing. In addition, the microscopic oil distribution characteristics change after flooding. During the near-miscible phase, class I and class III reservoirs predominantly yield oil from medium and small pores, while class II reservoirs primarily produce oil from medium pores. Upon reaching miscibility, oil production in class I, II, and III reservoirs primarily occurs in small pores, with some contribution from medium pores. The research findings presented in this paper provide valuable theoretical support for future CO2 flooding operations in tight sandstone reservoirs and the optimization of huff-n-puff experiments subsequent to flooding.
Water is ubiquitous within organic-rich shale in cases of connate water occurrence and during hydraulic fracturing treatment. Understanding multiphase transport behaviors in organic nanopores is ...crucial for the efficient development of shale gas reservoirs. However, current studies have predominantly focused on single-phase or two-phase transport behaviors in ideal graphite nanopores, leaving the understanding of multiphase transport processes within realistic kerogen-based nanopores limited. In this study, we conducted molecular dynamic simulations to investigate shale gas transport behaviors through organic nanopores constructed with realistic kerogen. The results reveal that, due to the complex composition in the chemistry and physics of kerogen macromolecules, gas transport through kerogen nanopores manifests parabolic-shaped velocity distributions with a negligible slip length at the walls, in contrast to the observations of fast mass transport in previous studies using smooth carbon-based skeleton nanopores. In water-saturated nanopores, H2O molecules tend to aggregate at the walls, forming water clusters, and eventually, a water pillar across the pore can be observed. As a result, a water blockage is formed, while the water film or water bridge dominates in some inorganic minerals. The presence of H2O molecules has a dramatic impact on shale gas transport capacity. On this basis, an analytical model was proposed to quantitatively characterize shale gas transport behaviors under different water saturations. The results demonstrate that the traditional continuous model with no-slip assumption remains applicable because of the rough kerogen surface and hindrance of water clusters, advancing the understanding of multiphase transport behaviors in shale nanopores and exploitation of shale gas reservoirs.
The thermal conductivity of hydrate-bearing sediments is a key parameter used to evaluate the heat characteristics relevant to phase transformations during gas production. In this study, considering ...the dynamic evolution of hydrate saturation, a high-pressure experimental apparatus was designed, and the steady-state method was used to measure the effective thermal conductivity of hydrate-bearing sediments. The reliability of the experimental apparatus was verified through the effective thermal conductivity measurement using pure ice and agar gel as standard materials, and optimization of the experimental parameters was carried out. The effective thermal conductivity of hydrate-bearing sediments with the initial water saturation range of 20–60% and the hydrate saturation range of 7.43–48.74% was measured. The results reveal that the effective thermal conductivity of hydrate-bearing sediments increases with increasing hydrate saturation and shows a maximum value in the hydrate saturation range of 25–36%. Moreover, the effective thermal conductivity of the hydrate-bearing sediment is also strongly dependent on the hydrate occurrence patterns and growth habits. In sediments with a low water saturation (30%), gas is the initial main continuous phase, and the maximum difference in thermal conductivity between the sediment with and without hydrates is 40.15%. For a high water saturation in sediments (60%), water is the initial main continuous phase, and the maximum difference in thermal conductivity between the sediment with and without hydrates is 10.59%, indicating that the positive contribution of hydrate formation on effective thermal conductivity is decreased. In addition, a developed fitting model, considering the influence of hydrate saturation in sediments, was proposed. The calculated results of the model are in good agreement with the experimental data for different samples.
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