Underground hydrogen storage: A comprehensive review

Increased emissions of greenhouse gasses into the atmosphere has adversely been contributing to global warming as a result of burning fossil fuels. Therefore, the energy sectors have been looking into renewable sources such as wind, solar, and hydro energy to make electricity. However, the strongly fluctuating nature of electricity from such energy sources requires a bulk energy storage system to store the excess energy as a buffer and to fulfill the demand constantly. Underground storage is a proven way to store a huge amount of energy (electricity) after converting it into hydrogen as it has higher energy content per unit mass than other gases such as methane and natural gas. This paper reviews the technical aspects and feasibility of the underground storage of hydrogen into depleted hydrocarbon reservoirs, aquifers, and manmade underground cavity (caverns). Mechanisms of underground hydrogen storage (UHS) followed by numerous phenomena such as hydrodynamics, geochemical, physiochemical, bio-chemical, or microbial reactions have been deliberated. Modeling studies have also been incorporated in the literature to assess the feasibility of the process that are also reviewed in this paper. Worldwide ongoing lab study, field study together with potential storage sites have been reported as well. Technical challenges along with proper remedial techniques and economic viability have been briefly discussed. Finally, this paper delivers some feasible strategies for the underground hydrogen storage process, which would be helpful for future research and development of UHS.     

What is this page known for? Computing Web page reputations

The textual content of the Web enriched with the hyperlink structure surrounding it can be a useful source of information for querying and searching. This paper presents a search process where the input is the URL of a page, and the output is a ranked set of topics on which the page has a reputation. For example, if the input is www.gamelan.com, then a possible output is ‘Java'. We propose several algorithmic formulations of the notion of reputation using simple random walk models of Web-browsing behavior. We give preliminary test results on the effectiveness of these algorithms.     

Effects of the trench geometry on vibration mitigation level in high-speed railway tracks

Train-induced ground vibration is numerically analyzed using the finite element method (FEM) in this paper. Varieties of open trenches including partial and full length systems with different geometries are employed as the vibration mitigation strategies. Ground is modeled by multiple soil layers and the train load pattern is simulated by series of successive moving loads. A parametric study is then carried out after verification of the numerical model. Effects of different parameters including the trench type, size and geometry and the train speed on the vibration mitigation level are investigated. The operational speeds are set to be in vicinity of the Rayleigh wave propagation velocity. Two types of active and passive trenches are considered with three different geometries consisting of rectangular, triangular (wedge) and circular cross sections.     

Preparation and photocatalytic study of CoFe2O4/TiO2/Au nanocomposites and their applications in organic pollutant degradation and modeling by an artificial neural network (ANN)

Journal of Materials Science: Materials in Electronics - Due to the increase of environmental pollution by various industries in recent decades, preparing drinking water has become one of the most...     

Effect of the Geometry of a Swirl Generator on Energy Loss and Shockwave Position in Arina Nozzle

To investigate the effect of the swirl generator (SG) on shockwave position and pressure drop, 3D simulation is conducted and validated by Arina's study. An increase of the blade number, height, and end angle leads to shockwave displacement toward the nozzle outlet. The maximum increment of the shockwave displacement, which is due to enlarging the angle of the blade end, is about 47 %. For this case, the pressure drop share of the SG is nearly half of the total pressure drop, while the residence time of particles is prolonged by about 51 %. As a general finding, increasing the swirl intensity provides a longer residence time to separate adequately the liquid from the gas. However, a higher energy loss is not desirable for the high-pressure process at the downstream of the 3S separator.     

The effect of MIO pigments on corrosion resistance and adhesion of synthetic rubber-based primer

In this research, the corrosion resistance and adhesion property of a synthetic rubber-based primer reinforced with different ratios of micaceous iron oxide (MIO) pigments were studied. Coatings were applied on carbon steel panels and also on steel pipes of 219.1 mm outer diameter. Scanning electron microscopy (SEM) was used to investigate the dispersion of MIO particles in the rubbery matrix. The anticorrosion performance of the coatings was studied, using electrochemical impedance spectroscopy (EIS) and salt spray tests. In addition, the adhesion of primers to carbon steel substrates was evaluated by pull-off test. In order to investigate the effect of MIO particles on the flexibility of the pigmented primers, a cupping test was conducted. The adhesion of cold-applied tape to the formulated primers was assessed by peel adhesion test using hanging mass method. The results indicated that adding 5, 10, and 15 wt% of MIO pigments into the primer improved corrosion resistance of the coatings. An increase in the MIO loading up to 10 wt%, improved the adhesion of the primer to both steel substrate and cold-applied tape.     

Modeling of naphtha reforming unit applying detailed description of kinetic in continuous catalytic regeneration process

Naphtha reforming is one of the most important processes in refineries in which high value-added reformate for gasoline pool and aromatics such as benzene, toluene, and xylene are produced. It is necessary to establish new naphtha reforming units and develop the traditional units to increase the efficiency of the processes. In this study, according to the recent progresses in the naphtha reforming technology, mathematical modeling of this process in continuous catalyst regeneration mode of operation is accomplished in two dimensions (radial and axial) by considering cross flow pattern. In addition, a new catalyst deactivation model has been proposed and a new reaction network model based on 32 pseudo-components with 84 reactions is investigated. Then, this model has been validated by comparing with industrial data, and its results have acceptable agreement.     

Modeling the Dispersion of Volatile Organic Compounds in Indoor Environment

Indoor air pollution belongs to the factors which puts the health of the corresponding occupants at risk. Effects of ventilation and, hence, various air flow regimes as parameters contributing to reduced air pollution in indoor spaces were further studied. For this purpose, air flow and distribution of the pollutant concentration were three‐dimensionally modeled at various ventilation rates. Results indicate that an increase in input air flow rate into the room in early times directly contributes to enhanced concentration of the pollutant in the indoor space. In general, with increasing the ventilation rate and changing the fluid‐flow regime from laminar to turbulent, the average concentration of the pollutant inside the indoor space decreased significantly.     

Optimal distribution function determination for plus fraction splitting

Reservoir fluid modelling is one of the most important steps in reservoir simulation and modelling of flow lines as well as surface facilities. One of the most uncertain parameters of the reservoir fluids is the plus fraction. An accurate and consistent splitting scheme can reduce this uncertainty and as a result, enhance the modelling of reservoir fluids. The existing schemes for splitting plus fractions are all based on assuming a specific mole fraction‐molecular weight distribution with predefined constant values that may yield inaccurate and inconsistent results. In this study, an optimization‐based algorithm was developed to determine the aforementioned controlling parameters of the plus fraction distribution function, enforcing the relationship between specific gravity and molecular weight of the single carbon numbers (SCNs). The introduced optimization‐based splitting technique was applied to different samples, covering a wide range of reservoir fluids, including gas condensates, volatile oils, black oils, and heavy oils. The results showed that the proposed technique yielded a more consistent molecular weight‐mole fraction distribution concerning the experimental extended analysis of plus fractions, yielding an average relative error of 25.8 % compared to 76, 33.6, and 45.9 % for the Katz, Ahmed, and Whitson methods, respectively. It was also shown that the proposed method results in more accurate and more consistent phase behaviour predictions than the existing methods concerning the experimental data. Furthermore, the results showed that the introduced optimization‐based method yields monotonic split samples regarding specific gravity and molecular weight, while the conventional techniques do not guarantee to preserve the monotonicity.