47,987 research outputs found

    Gas Hydrates: It's A Gas!

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    In this activity, students will investigate the occurrence of gas hydrates on the ocean floor. They will discover the importance of carbon, where carbon is stored on Earth, and that the largest reservoir of carbon is gas hydrates. Students will discover that Earth's climate changes, and how the greenhouse effect works. They will also learn about the potential of hydrates as a major new energy resource and explore the conditions under which hydrates form. Educational levels: High school

    Clathrate type 2 hydrate formation in vacuo under astrophysical conditions

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    The properties of clathrate hydrates were used to explain the complex and poorly understood physical processes taking place within cometary nuclei and other icy solar system bodies. Most of all the experiments previously conducted used starting compositions which would yield clathrate types I hydrates. The main criterion for type I vs. type II clathrate hydrate formation is the size of the guest molecule. The stoichiometry of the two structure types is also quite different. In addition, the larger molecules which would form type II clathrate hydrates typically have lower vapor pressures. The result of these considerations is that at temperatures where we identified clathrate formation (120-130 K), it is more likely that type II clathrate hydrates will form. We also formed clathrate II hydrates of methanol by direct vapor deposition in the temperature range 125-135 K

    Development of media for dynamic latent heat storage for the low-temperature range. Part 1: Thermal analyses of selected salt hydrate systems

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    Phase change temperatures and phase change enthalpies of seventeen salt hydrates, three double salts, and four eutectics were measured thermodynamically and the results reported herein. Good results were obtained, especially for congruently melting salt hydrates. Incongruently melting salt hydrates appear less suitable for heat storage applications. The influence of the second phase - water, acid and hydroxide - to the latent heat is described. From these results, basic values of the working temperatures and storage capabilities of various storage media compositions may be derived

    Volatile inventories in clathrate hydrates formed in the primordial nebula

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    Examination of ambient thermodynamic conditions suggest that clathrate hydrates could exist in the martian permafrost, on the surface and in the interior of Titan, as well as in other icy satellites. Clathrate hydrates probably formed in a significant fraction of planetesimals in the solar system. Thus, these crystalline solids may have been accreted in comets, in the forming giant planets and in their surrounding satellite systems. In this work, we use a statistical thermodynamic model to investigate the composition of clathrate hydrates that may have formed in the primordial nebula. In our approach, we consider the formation sequence of the different ices occurring during the cooling of the nebula, a reasonable idealization of the process by which volatiles are trapped in planetesimals. We then determine the fractional occupancies of guests in each clathrate hydrate formed at given temperature. The major ingredient of our model is the description of the guest-clathrate hydrate interaction by a spherically averaged Kihara potential with a nominal set of parameters, most of which being fitted on experimental equilibrium data. Our model allows us to find that Kr, Ar and N2_2 can be efficiently encaged in clathrate hydrates formed at temperatures higher than \sim 48.5 K in the primitive nebula, instead of forming pure condensates below 30 K. However, we find at the same time that the determination of the relative abundances of guest species incorporated in these clathrate hydrates strongly depends on the choice of the parameters of the Kihara potential and also on the adopted size of cages. Indeed, testing different potential parameters, we have noted that even minor dispersions between the different existing sets can lead to non-negligible variations in the determination of the volatiles trapped in clathrate hydrates formed in the primordial nebula.Comment: Accepted for publication in Faraday Discussion

    On the thermodynamic stability and structural transition of clathrate hydrates

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    Gas mixtures of methane and ethane form structure II clathrate hydrates despite the fact that each of pure methane and pure ethane gases forms the structure I hydrate. Optimization of the interaction potential parameters for methane and ethane is attempted so as to reproduce the dissociation pressures of each simple hydrate containing either methane or ethane alone. An account for the structural transitions between type I and type II hydrates upon changing the mole fraction of the gas mixture is given on the basis of the van der Waals and Platteeuw theory with these optimized potentials. Cage occupancies of the two kinds of hydrates are also calculated as functions of the mole fraction at the dissociation pressure and at a fixed pressure well above the dissociation pressure

    The Big Burp: Where's the Proof?

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    This lesson focuses on the possible release of methane from methane hydrates to the atmosphere and the potential impact of these releases on global warming, particularly how they might be involved with the Cambrian explosion and the Paleocene extinction events. Students will use online resources to research these events and to learn what methane hydrates are and how they might contribute to global warming. They will also describe and give evidence to support the hypothesis that methane hydrates contributed to the Cambrian explosion and Paleocene extinction events. Educational levels: High school

    3-D numerical modeling of methane hydrate deposits

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    Within the German gas hydrate initiative SUGAR, we have developed a new tool for predicting the formation of sub-seafloor gas hydrate deposits. For this purpose, a new 2D/3D module simulating the biogenic generation of methane from organic material and the formation of gas hydrates has been added to the petroleum systems modeling software package PetroMod®. T ypically, PetroMod® simulates the thermogenic generation of multiple hydrocarbon components including oil and gas, their migration through geological strata, and finally predicts the oil and gas accumulation in suitable reservoir formations. We have extended PetroMod® to simulate gas hydrate accumulations in marine and permafrost environments by the implementation of algorithms describing (1) the physical, thermodynamic, and kinetic properties of gas hydrates; and (2) a kinetic continuum model for the microbially mediated, low temperature degradation of particulate organic carbon in sediments. Additionally, the temporal and spatial resolutions of PetroMod® were increased in order to simulate processes on time scales of hundreds of years and within decimeters of spatial extension. As a first test case for validating and improving the abilities of the new hydrate module, the petroleum systems model of the Alaska North Slope developed by IES (currently Shlumberger) and the USGS has been chosen. In this area, gas hydrates have been drilled in several wells, and a field test for hydrate production is planned for 2011/2012. The results of the simulation runs in PetroMod® predicting the thickness of the gas hydrate stability field, the generation and migration of biogenic and thermogenic methane gas, and its accumulation as gas hydrates will be shown during the conference. The predicted distribution of gas hydrates will be discussed in comparison to recent gas hydrate findings in the Alaska North Slope region

    Gas Hydrates: It's a Gas

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    In this activity, students will discover the importance of carbon, where carbon is stored on Earth, and that the largest reservoir of carbon is in the form of gas hydrates where methane and other hydrocarbon gases are trapped in a lattice of water molecules in deep sea sediments. Students will learn how climate change is related to the greenhouse effect. They will also learn about the potential of hydrates as a major new energy resource, and explore the conditions under which hydrates form. In addition, students will understand the use of acoustics for mapping the sea floor and sub-sea floor. Educational levels: High school

    Technological complex for production, transportation and storage of gas from the offshore gas and gas hydrates fields

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    Purpose. Substantiation and development of schematics acceptable for the existing technological methods of natural gas production and transportation from the offshore fields of gas or gas hydrates. Improvement of their efficiency by way of maximum reduction of energy consumption as the result of complex consideration of thermal and physical properties and parameters of the system components interaction in the deposit under development. Methods. Analysis and generalization of the results of complex experimental research performed on the multifunctional laboratory gas hydrate installation. Findings. The technology of gas hydrates extraction from the productive reservoir without energy consumption for the phase transition is proposed. It is proved that simultaneous development of gas hydrate fields and gas fields via binding free gas into gas hydrate by ensuring necessary temperature and pressure conditions during gas passing through the sea waterbody is expedient. The feasibility of combining in one chain the proposed technology of the developing the offshore gas and gas hydrate fields with technology of gas transportation in hydrate form and its preservation in ground storages is proved. Originality. It was substantiated that gas hydrates can be extracted from the productive reservoir without energy consumption for dissociation, by creating conditions of its recrystallization as a result of joint actions of submerged jets of sea water in the mixture with abrasive material and pressure fluctuations. Practical implications. The proposed gas hydrate technology creates important prerequisites for the development of small and medium remote gas deposits (including gas hydrate ones), the network of ground hydrates storages, improves the efficiency and competitiveness of technology for marine transportation of natural gas in hydrate formМета. Обґрунтування і розробка принципових схем, прийнятних для існуючого рівня техніки, способів видобування й транспортування природного газу, газових або газогідратних морських родовищ, та підвищення їх ефективності шляхом максимального зниження енерговитрат у результаті комплексного урахування теплофізичних властивостей і параметрів взаємодії складових системи у межах покладу, що розробляється. Методика. Аналіз та узагальнення результатів комплексу експериментальних досліджень, проведених на багатофункціональній лабораторній газогідратній установці. Результати. Запропоновано технологію вилучення газогідрату із продуктивного пласта без витрати енергії на фазовий перехід. Обґрунтовано доцільність сумісної розробки газогідратних і газових родовищ шляхом зв’язування вільного газу в газогідрат за рахунок наявності необхідних термобаричних умов при його проходженні крізь морську товщу. Обґрунтовано доцільність поєднання в один ланцюг запропонованої технології розробки морських газогідратних і газових родовищ з технологіями транспортування газу у газогідратній формі та його зберігання у наземних сховищах. Наукова новизна. Обґрунтовано можливість вилучення газогідрату із продуктивного пласта без витрати енергії на дисоціацію шляхом створення умов його перекристалізації у результаті сумісної дії затоплених струменів морської води у суміші з абразивним матеріалом та пульсацій тиску. Практична значимість. Запропонована газогідратна технологія створює важливі передумови розробки малих та середніх віддалених родовищ газу (у тому числі й газогідратних), створення мережі наземних гідратосховищ, підвищення ефективності та конкурентоздатності технології морського транспортування природного газу у газогідратній формі.Цель. Обоснование и разработка принципиальных схем, приемлемых для существующего уровня техники, способов добычи и транспортировки природного газа, газовых или газогидратных морских месторождений и повышение их эффективности путем максимального снижения энергозатрат в результате комплексного учета теплофизических свойств и параметров взаимодействия элементов системы в пределах разрабатываемой залежи. Методика. Анализ и обобщение результатов комплекса экспериментальных исследований, выполненных на многофункциональной лабораторной газогидратной установке. Результаты. Предложена технология извлечения газогидрата из продуктивного пласта без затрат энергии на фазовый переход. Обоснованно целесообразность совместной разработки газогидратных и газовых месторождений путем связывания свободного газа в газогидрат за счет наличия необходимых термобарических условий при его прохождении сквозь морскую толщу. Обоснованно целесообразность объединения в одну цепь предложенной технологии разработки морских газогидратных и газовых месторождений с технологиями транспортировки газа в газогидратной форме и его хранения в наземных хранилищах. Научная новизна. Обоснована возможность извлечения газогидрата из продуктивного пласта без затрат энергии на диссоциацию путем создания условий его перекристаллизации в результате совместного воздействия затопленных струй морской воды в смеси с абразивным материалом и пульсаций давления. Практическая значимость. Предложенная газогидратная технология создает важные предпосылки разработки малых и средних отдаленных месторождений газа (в том числе и газогидратных), создания сети наземных гидратохранилищ, повышения эффективности и конкурентоспособности технологии морской транспортировки природного газа в газогидратной форме.This work has become possible due to financial and organizational support within the frames of the state budget research project under the auspices of the Ministry of Education and Science of Ukraine “Application of gas hydrate technology in the development of traditional and gas hydrate gas deposits” No 0113U00857, “Research of influence of thermodynamic parameters of phase transitions in systems with gas hydrates on the efficiency of gas hydrate technology” No 0115U002420. The authors express their gratitude to the supervisor of these projects – Doctor of Sciences, Professor, Head of the Underground Mining Department at the National Mining University (Dnipropetrovsk) Volodymyr Bondarenko for his support in conducting the research