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Abstract The effects of the operating conditions on the performance of metal hydride hydrogen storage tanks are complicated and need detailed investigations for further optimization. In this study, a mathematical model is developed to understand the effects of the various operating conditions on the hydrogen absorption processes in a LaNi 5 metal hydride tank. The numerical results indicate that the quickest charging process occurs within the first 20 s, and the quickest charging rate and duration are mainly affected by the charging pressure and initial temperature, respectively. The effect of cooling level on this process is insignificant. For both the short-time charging (2 min) and long-time charging, the hydrogen fueling performance is significantly affected by the cooling level (the heat transfer coefficient and surrounding temperature) and charging pressure. In order to ensure sufficiently quick hydrogen charging, the charging pressure needs to be kept enough higher than the equilibrium pressure, and due to the fast heating of the metal hydride, the influence of the initial temperature is less significant than the cooling condition. The general distributions of the absorbed hydrogen fraction and temperature are similar under the different operating conditions.

Abstract Hydration is an alternative promising method for CO2 capture and separation from either post-combustion flue gas or pre-combustion fuel gas. The present paper gathers the researches on CO2 hydrate and the hydrates of gas mixtures of CO2+N2/H2/CH4, including studies of fundamental thermo-physical properties, molecular structures and hydrate formation equilibrium conditions. Some promoters, i.e. quaternary ammonium salt etc. are usually used in CO2 hydration process to reduce the hydrate equilibrium pressure and to enhance the hydrate kinetic and stability, hence their promotion effect on CO2 hydrate and on the hydrates of gas mixture of CO2+N2/H2/CH4 are reviewed. The paper also summarizes the applications of hydrate technology in CO2 capture and separation, and the corresponding performance is summarized and the bottlenecks are discussed. It necessitates more works to promote this technology towards industrial application.

Abstract The aim of this paper is to describe the methodology developed to link the quantitative outputs of the geosphere risk assessment to the semi-quantitative assessment of risk to the biosphere. It also shows how good practice stakeholder engagement principles can be incorporated into the risk assessment process to achieve transparency in project decision making. The objective of the biosphere risk assessment portion of the Weyburn-Midale Project was to develop a risk assessment methodology that can be applied to a range of CO2 storage projects. Preliminary modelling of potential biosphere impacts associated with the Weyburn-Midale Project was undertaken to enable the risk assessment methodology to be tested and to demonstrate the nature of the biosphere risk assessment outputs, and how the process and outputs can be used to facilitate stakeholder acceptance. The method to assess the biosphere risk at the Weyburn-Midale Project uses the outputs (pathways, likelihoods and CO2 mass) from geosphere risk assessment to identify the general physical and chemical effects on the fundamental biosphere components (groundwater, surface water, soil, air) and the consequential impacts on organisms, habitat, amenity and public safety. The approach applies an existing environmental impact assessment methodology to derive outputs that stakeholders can use to assess the risk and impacts to environmental assets. The outcomes of biosphere risk assessment are used to: develop risk mitigation strategies and future monitoring options; understand whether the project will likely have unacceptable impacts on safety or valued community assets; decide whether the project should proceed; and to assist engagement with regulators and the community.

Abstract The dissolution of carbon dioxide (CO 2 ) in deep saline aquifer water is recognized as one of the fundamental mechanisms in the subsurface for storing significant quantities of CO 2 . One fundamental physical effect of CO 2 dissolution is the slight increase in water density in the layer in contact with the buoyant free-phase CO 2 plume. Under specific conditions, this may lead to gravitational instability and the onset of free convection, significantly accelerating the dissolution of the free-phase CO 2 by bringing CO 2 in contact with a larger volume of aquifer water. It is also feasible to enhance CO 2 dissolution using engineering methodologies such as injecting water on top of the plume of CO 2 . The objective of this review is to provide a perspective on the progress in modeling and experimental observations of physical aspects of CO 2 dissolution in deep saline aquifers. We review the published research efforts concerning the physical effects of CO 2 dissolution in formation water, the conditions under which process can be accelerated either naturally, such as by free convection, or by use of engineering methodologies, and the effects of CO 2 dissolution on CO 2 storage. Finally, we discuss areas in need of further research.

The storage and transport of gases in coal is of tremendous importance in the utilisation of coalbeds, and in particular the recovery of methane. There is also increasing interest in the use of coal mines as sites for carbon dioxide sequestration to alleviate the potentially harmful effects of global warming. This paper demonstrates the use of magnetic resonance imaging to investigate the spatiotemporal dynamics of gas transport in coal. The presence of significant structural heterogeneities in the coal was observed. Dynamical effects displayed a broad range of time constants ranging from minutes to days.

Abstract Xylose is a by-product of lignocellulosic biomass processing for production of second-generation biofuels and could be suitable for bioproduct manufacturing. This paper describes an innovative approach that enables the system to achieve high yielding for hydrogen production. The study compared 4 physicochemical pre-treatments performed in an anaerobic mixed culture (acidic, thermal, acidic-thermal and thermal acidic) to achieve an inoculum with a high-efficiency xylose to hydrogen conversion under mesophilic conditions (30 °C). The acidic pre-treatment was the most efficient to select microorganisms able to produce hydrogen and volatile acid from xylose. Kinetics has shown that acidic pre-treatment had a hydrogen/xylose molar yielding factor of 1.57 (molar base) and a hydrogen maximum production rate of 253 mL H2 h−1. Mass balance considered all possible metabolic pathways using xylose as a substrate. Anaerobic degradation of ethanol was the most active pathway for hydrogen production in all experiments, except for the control. Each pre-treatment performed for the original inoculum resulted in different microbiological profiles, but the genus Clostridium was the most abundant in all assays. Acidic pre-treatment stimulated the growth of organisms from the genera Peptostreptococcaceae, Truepera and Kurthia, which could be related to the better results in hydrogen production found in this condition.

Abstract This study conducts a literature survey on the chemical steam additives tested in both lab and field settings from 1982 to present (2020). We summarize the major recovery mechanisms of both steam-based recovery process and steam-chemical-based recovery process. Next, we review the previous lab-scale/field-scale studies examining the applications of surfactants, alkali, and novel chemicals in the steam-based oil recovery process. Among the different surfactants studied, alpha-olefin sulfonate (AOS) and linear toluene sulfonate (LTS) are the recommended chemicals for their foam control/detergency effect. In particular, AOS was observed to perform especially well in residual oil saturation (ROS) reduction and sweep efficiency improvement when being co-injected with alkali. Application of organic alkali (alone or with a co-surfactant) has also drawn wide attention recently, but its efficacy in the field requires further investigation and the consumption of alkali by sands/clay is often an inevitable issue and, therefore, how to control the alkali loss requires further investigation. Novel chemical additives tested in the past five years include fatty acids (such as tail oil acid, TOA-Na+), Biodiesel (o/w emulsion), along with other types of chemical additives including switchable hydrophilicity tertiary amines (SHTA), chelating agents, Deep Eutectic Solvents (DES), graphite and SiO2 particles, ionic liquids and urea. High thermal stability of some of the novel chemicals and their potential in increasing displacement efficiency and ROS reduction efficiency in the lab studies require further investigation for their optimized application in the field settings to minimize the use of steam while improving the recovery effectively. This review reveals that when being properly applied, chemical additives can improve oil recovery via steam foam control, detergency effect (IFT reduction and wettability control), and viscosity reduction. In certain cases, microemulsion generation could be observed (o/w or w/o) with the addition of chemical additives at steam condition (which leads to recovery improvement), but the microemulsion effect on the conformance control (separate from the foamy effect), is lacking detailed investigation.

Theoretical mean wave resistance and regional division of the energy of single-layer flow over topography is studied at the near-resonant region in the weakly nonlinear, long wave limit. The theoretical mean wave resistance is determined in terms of the 1st and 2nd conservation laws of the fKdV equation. It is proved by the asymptotic mean method that the theoretical mean wave resistance depends only on the intensity and moving velocity of the topography. The theoretical results of this paper are in good agreement with numerical calculations. Comparisons between the theoretical and numerical results showed that the theory of the present paper holds for any small compact topography.

Abstract Several researchers have studied the Sleipner model to understand the inherent flow physics better, to find a satisfactory match of the CO2 plume migration. Various sources of uncertainty in the geological model and the fluid have been investigated. Most of the work undertaken on the Sleipner model employed the one factor at a time (OFAT) method and analysed the impact of uncertain parameters on plume match individually. In this study, we have investigated the impact of some of the most cited sources of uncertainties including porosity, permeability, caprock elevation, reservoir temperature, reservoir pressure and injection rate on CO2 plume migration and structural tapping in the Sleipner. We tried to fully span the uncertainty space on Sleipner 2019 Benchmark (Layer 9) using a vertical-equilibrium based simulator. To the best of our knowledge, this is the first time that a study has focused on the joint effect of six uncertain parameters using data-driven models. This work would raise our scientific understanding of the complexity of the impact of the reservoir uncertainty on CO2 plume migration in a real field model. The caprock elevation was shown to be the most important parameter in controlling the plume migration (overall importance of 26 %) followed by injection rate (24 %), temperature (22 %), heterogeneity in permeability (13 %), pressure (9 %) and porosity (6 %).