Natural gas clathrate-hydrates

Natural gas clathrate hydrates normally form either in the primitive cubic structure I, in the face-centered cubic structure II, or in the hexagonal structure H. 

Hydrate research has expanded substantially over the past decade, resulting in more than 4,000 hydrate-related publications. Collating this vast amount of information into one source, Clathrate Hydrates of Natural Gases, Third Edition presents a thoroughly updated, authoritative, and comprehensive description of all major aspects of natural gas clathrate hydrates. 

Provides a historical perspective of natural gas clathrate hydrates existing from 1790 to 2006... 

Answers to such difficult questions can be found in applied thermodynamics - in terms of measured, macroscopic values of pressures, temperatures, compositions, volumes, enthalpies, etc. This chapter provides an overview of natural gas clathrate hydrates - structures, phase diagrams, and thermodynamic predictions/measurements that guide our understanding in dealing with such questions. The hydrate historical perspective provides an example of how knowledge advances in a technical field. At the conclusion of the chapter, future thermodynamic challenges are presented. 

Smelik, E.A. King, H.E. Jr. Crystal-growth studies of natural gas clathrate hydrates using a pressurized optical cell American Mineralogist, 82(l-2)( 1997)88-98. 

In this work, we have presented new experimental 3-phase H-Lw V (Hydrate - Liquid Water- Vapour) equilibrium data for methane and a natural gas clathrate hydrates in the presence of high concentrations of mono-ethylene glycol solutions, generated by a reliable fixed-volume (isochoric), step-heating technique. These data in addition to data from literature have been used to validate the predietive capabilities of a thermodynamic model presented in this work. 

Naturally occurring clathrate hydrates are found in marine sediments and in permafrost. Because they contain a large amount of methane, they are thought to have potential as an unconventional energy resource. At the same time, however, clathrate hydrates are a serious problem for the gas and oil industries, because they form easily under suitable conditions at the sites of natural gas production, transportation, and processing. The inhibition and control of hydrates in pipelines adds tremendously to gas production costs. ... 

Several alternative methods have been considered in order to increase the energy density of natural gas and facilitate its use as a road vehicle fuel. It can be dissolved in organic solvents, contained in a molecular cage (clathrate), and it may be adsorbed in a porous medium. The use of solvents has been tested experimentally but there has been little improvement so far over the methane density obtained by simple compression. Clathrates of methane and water, (methane hydrates) have been widely investigated but seem to offer little advantage over ANG [4]. Theoretical comparison of these storage techniques has been made by Dignam [5]. In practical terms, ANG has shown the most promise so far of these three alternatives to CNG and LNG. 

Natural gas (methane) can be obtained from gas hydrates. Gas hydrates are also called clathrates or methane hydrates. Gas hydrates are potentially one of the most important energy resources for the future. Methane gas hydrates are increasingly considered a potential energy resource. Methane gas hydrates are crystalline solids formed by combination of methane and water at low temperatures and high pressures. Gas hydrates have an iee-hke crystalline lattiee of water molecules with methane molecules trapped inside. Enormous reserves of hydrates can be foimd imder eontinental shelves and on land under permafrost. The amount of organic... 

Several hundred to several thousand feet beneath the ocean floor in permafrost and continental edge regions lies a potentially vast source of natural gas in excess of 10 cubic meters of gas hydrates, consisting largely of methane clathrate (53-55). Gas... 

Deaton and Frost Gas Hydrates and Relation to the Operation of Natural-Gas Pipelines 1959 Katz et al. Water-Flydrocarbon Systems in Handbook of Natural Gas Engineering 1967 Jeffrey and McMullan The Clathrate Hydrates in Progress in Inorganic Chemistry... 

Holder et al. Phase Behavior in Systems Containing Clathrate Hydrates Rev. Chem. Eng. 1990 Katz and Lee Gas Hydrates and Their Prevention in Natural Gas Engineering ... 

---