A Hierarchical Framework for CO2 Storage Capacity in Deep Saline Aquifer Formations

Carbon dioxide (CO2) storage in deep saline aquifers is a vital option for CO2 mitigation at a large scale. Determining storage capacity is one of the crucial steps toward large-scale deployment of CO2 storage. Results of capacity assessments tend toward a consensus that sufficient resources are available in saline aquifers in many parts of the world. However, current CO2 capacity assessments involve significant inconsistencies and uncertainties caused by various technical assumptions, storage mechanisms considered, algorithms, and data types and resolutions. Furthermore, other constraint factors (such as techno-economic features, site suitability, risk, regulation, social-economic situation, and policies) significantly affect the storage capacity assessment results. Consequently, a consensus capacity classification system and assessment method should be capable of classifying the capacity type or even more related uncertainties. We present a hierarchical framework of CO2 capacity to define the capacity types based on the various factors, algorithms, and datasets. Finally, a review of onshore CO2 aquifer storage capacity assessments in China is presented as examples to illustrate the feasibility of the proposed hierarchical framework.

Periodic CO2 Injection for Improved Storage Capacity and Pressure Management under Intermittent CO2 Supply

Storing CO2 in geological formations is an important component of reducing greenhouse gases emissions. The Carbon Capture and Storage (CCS) industry is now in its establishing phase, and if successful, massive storage volumes would be needed. It will hence be important to utilize each storage site to its maximum, without challenging the formation integrity. For different reasons, supply of CO2 to the injection sites may be periodical or unstable, often considered as a risk element reducing the overall efficiency and economics of CCS projects. In this paper we present outcomes of investigations focusing on a variety of positive aspects of periodic CO2 injection, including pressure management and storage capacity, also highlighting reservoir monitoring opportunities. A feasibility study of periodic injection into an infinite saline aquifer using a mechanistic reservoir model has indicated significant improvement in storage capacity compared to continuous injection. The reservoir pressure and CO2 plume behavior were further studied revealing a ‘CO2 expansion squeeze’ effect that governs the improved storage capacity observed in the feasibility study. Finally, the improved pressure measurement and storage capacity by periodic injection was confirmed by field-scale simulations based on a real geological set-up. The field-scale simulations have confirmed that ‘CO2 expansion squeeze’ governs the positive effect, which is also influenced by well location in the geological structure and aquifer size, while CO2 dissolution in water showed minor influence. Additional reservoir effects and risks not covered in this paper are then highlighted as a scope for further studies. The value of the periodic injection with intermittent CO2 supply is finally discussed in the context of deployment and integration of this technology in the establishing CCS industry.

Effects of Oils and Fats on the Quality Characteristics, Nutritional Value, and Storage Capacity of Cookies

Introduction. The quality profile and nutritional values of cookies depend on the raw material. The research objective was to study the effect of oils and fats on the quality characteristics and storage capacity of cookies. Study objects and methods. The study involved such types of oils and fats as margarine, confectionery fat, milk fat substitute, palm oil, sunflower oil, and high oleic sunflower oil. It was based on standard methods of sensory, physicochemical, structural, and rheological analyses. Results and discussion. The experimental formulations relied on contemporary dilatory recommendations, consumer acceptability, and traditionality of sensory indicators. The mass fraction of fat was limited to ≤ 18%; added sugars – to ≤ 22%; salt – to ≤ 0.3%. For each type of oil and fat, as set of experiments was performed to define the optimal technological emulsion and dough parameters. Other aspects involved the patterns of moisture transfer, indicators of oxidative spoilage, fatty acid composition, sensory properties, physicochemical and microbiological indicators, storage capacity, etc. The samples with vegetable oils instead of fat had a lower content of saturated fatty acids, which fell from 8–9 to 2–3 g/100 g. However, the risk of oxidative spoilage increased significantly. On storage day 104, the content of linoleic acid in the samples with sunflower oil decreased from 62.0 to 60.4%, while the samples with high oleic sunflower oil maintained the same level of linoleic acid. The samples with confectionery fat and palm oil demonstrated the lowest rate of oxidative processes, while those with margarine and milk fat substitute had the best sensory profile after storage. Conclusion. The cookies with sunflower oil and high oleic sunflower oil appeared to have a shelf life of two months, while for those with milk fat substitute, margarine, palm oil, and confectionery fat it was six months. Further research should focus on various emulsifiers and antioxidants capable of forming bonds with proteins and starch fractions of flour, which could increase the resistance of liquid vegetable oils to oxidation.

Anodic Activity of Hydrated and Anhydrous Iron (II) Oxalate in Li-Ion Batteries

We discuss the applicability of the naturally occurring compound Ferrous Oxalate Dihydrate (FOD) (FeC2O4·2H2O) as an anode material in Li-ion batteries. Using first-principles modeling, we evaluate the electrochemical activity of FOD and demonstrate how its structural water content affects the intercalation reaction and contributes to its performance. We show that both Li0 and Li+ intercalation in FOD yields similar results. Our analysis indicates that fully dehydrated ferrous oxalate is a more promising anodic material with higher electrochemical stability: it carries 20% higher theoretical Li storage capacity and a lower voltage (0.68 V at the PBE/cc-pVDZ level), compared to its hydrated (2.29 V) or partially hydrated (1.43 V) counterparts.

Instrumental Methods for Cage Occupancy Estimation of Gas Hydrate

Studies revealed that gas hydrate cages, especially small cages, are incompletely filled with guest gas molecules, primarily associated with pressure and gas composition. The ratio of hydrate cages occupied by guest molecules, defined as cage occupancy, is a critical parameter to estimate the resource amount of a natural gas hydrate reservoir and evaluate the storage capacity of methane or hydrogen hydrate as an energy storage medium and carbon dioxide hydrate as a carbon sequestration matrix. As the result, methods have been developed to investigate the cage occupancy of gas hydrate. In this review, several instrument methods widely applied for gas hydrate analysis are introduced, including Raman, NMR, XRD, neutron diffraction, and the approaches to estimate cage occupancy are summarized.