Methane transportation

Nouchi I, Mariko S, Aoki K. Mechanism of methane transport from the rhizosphere to the atmosphere through rice plants. Plant Physiol. 1990 94 59-66. 

Nouchi I, Mariko S. Mechanisms of methane transport by rice plants. In Oremland RS, editor. Biogeochemistry of Global Change Radiatively Active Trace Gases. New York Chapman Hall 1993. pp. 336-352. 

Hosono T, Nouchi I. The dependence of methane transport in rice plants on the root zone temperature. Plant Soil, 1997 191 233-240. 

Aulakh MS, Wassmann R, Rennenberg H, Fink S. Pattern and amount of aerenchyma relate to variable methane transport capacity of different rice cultivars. Plant Biol. 2000 2 182-194. 

Yu KW, Wang ZP, Chen GX. Nitrous oxide and methane transport through rice plants. Biol. Fertil. Soils. 1997 24 341-343. 

In the models presented by Wang and Lin (1995], the catalytic reaction terms appear in the transport equations for the tube core where methane is introduced. Air flows in the annular region and permeates through the dense oxide membrane to the tube side to react with methane. Transport of oxygen takes place as a result of the defects of oxygen vacancy and electron-hole in the oxide layer. 

Chanton J. P., Martens C. S., Kelley C. A., Crill P. M., and Showers W. J. (1992a) Methane transport mechanisms and isotopic fractionation in emergent macrophytes of an Alaskan tundra lake. J. Geophys. Res. 97(D15), 16681-16688. 

Fechner E. J. and Hemond H. F. (1992) Methane transport and oxidation in the unsaturated zone of a Sphagnum peatland. Global Biogeochem. Cycles 6, 33-44. 

Another driving force for methane transport is the generation of critical pressures in the gas phase (Flemings et al. 2003 Trehu et al. 2004). Interconnection of gas-filled pores below the GHSZ transmits hydrostatic pressures from greater depths because of the low density of the gas phase. The excess (non-hydrostatic) pressure at the top of the gas layer may be sufficient to... 

Torres, M.E., Wallmann, K., Trehu, A.M., Bohrmann, G, Borowski, W.S., and Tomaru, H., 2004. Gas hydrate growth, methane transport, and chloride enrichment at the southern summit of Hydrate Ridge, Cascadia margin off Oregon. Earth and Planetary Science Letters, 226 225-241. 

Approximately 90% of the methane transport from soils to the atmosphere in rice paddies and freshwater marshes is through aerenchyma portion of roots and stems of the plants. Gases are transported according to their concentration gradient, not only for CH4 but also for N2O (Yu et al.,... 

FIGURE 16.2 Pathway of methane transport from the rhizosphere to the atmosphere through wetland plants. 

Although this process offers the advantage of driving a low temperature, carefully controlled oxidation of methane, thereby increasing the yield of methanol, it also utilizes sulfuric acid to produce the intermediate methyl bisulfate. The need for acid resistant containers to perform these reactions may raise costs of the process. And although the sulfuric acid is recovered and recycled into the process, the environmental benefits of this methane conversion are somewhat offset by the need to ship and store hazardous sulfuric acid. The trade-off between safer methane transport versus increased sulfuric acid transport and storage needs to be considered from the perspective of accidental releases. 

Moreover, this porous compound is also applicable for efficient separation of mixed gases, CO2/N2 and C02/CF14, which are useful in air purification and methane transportation systems [235]. Kinetic diameters of CO2, N2, and CH4 are 3.30, 3.64, and 3.80A, respectively. The small pores of 4.0 x 4.0A within this compound has limited the packing of these three gas molecules within the micropores to a single-layer packing that simplifies the complicated adsorption phenomena and process. The adsorption isotherms for each component at different temperatures... 

Although many problems still remain to be overcome to make the process practical (not the least of which is the question of the corrosive nature of aqueous HBr and the minimization of formation of any higher brominated methanes), the selective conversion of methane to methyl alcohol without going through syn-gas has promise. Furthermore, the process could be operated in relatively low-capital-demand-ing plants (in contrast to syn-gas production) and in practically any location, making transportation of natural gas from less accessible locations in the form of convenient liquid methyl alcohol possible. 

Still another possibiUty is a marine biomass plantation such as that envisaged for giant brown kelp grown off the California coast and conversion of the kelp to methane in a system similar to that shown in Figure 19. The location of the SNG plant could be either on a floating platform near the kelp growth area or located on shore, in which case the biomass or fuel transport requirements would be different. 

Liquefied natural gas (LNG) also plays a large role in both the transportation and storage of natural gas. At a pressure of 101.3 kPa (1 atm), methane can be Hquefted by reducing the temperature to about — 161°C. When in the Hquid form, methane occupies approximately 1/600 of the space occupied by gaseous methane at normal temperature and pressure. In spite of the very low temperature of the Hquid, LNG offers advantages for both shipping and storing natural gas. 

The largest pipeline transport of gas, by far, is the movement of methane (natural gas). Natural gas can be Hquefted, but it is not pipelined in Hquid form because of cost and safety considerations. For overseas transport, it is shipped as Hquefted natural gas (LNG) in insulated tankers, unloaded at special unloading faciHties, vaporized, and then transported over land in pipelines as a gas. 

Euture large gasification plants, intended to produce ca 7 x 10 m standard (250 million SCE) of methane per day, are expected to be sited near a coal field having an adequate water supply. It is cheaper to transport energy in the form of gas through a pipeline than coal by either rail or pipeline. The process chosen is expected to utilize available coal in the most economical manner. 

Coal Hquefaction iavolves raising the atomic hydrogen-to-carbon ratio from approximately 0.8/1.0 for a typical bituminous coal, to 2/1 for Hquid transportation fuels or 4/1 for methane (4). In this process, molecular weight reduction and removal of mineral matter and heteroatoms such as sulfur, oxygen, and nitrogen may need to be effected. 

The mixed refrigerant cwcle was developed to meet the need for hq-uefying large quantities of natural gas to minimize transportation costs of this fuel. This cycle resembles the classic cascade cycle in principle and may best be understood by referring to that cycle. In the latter, the natural gas stream after purification is cooled successively by vaporization of propane, ethylene, and methane. Each refrigerant may be vaporized at two or three pressure levels to increase the natural gas coohng efficiency, but at a cost of considerable increased process complexity. 

Adsorption of supercritical gases takes place predominantly in pores which are less than four or five molecular diameters in width. As the pore width increases, the forces responsible for the adsorption process decrease rapidly such that the equilibrium adsorption diminishes to that of a plane surface. Thus, any pores with widths greater than 2 nm (meso- and macropores) are not useful for enhancement of methane storage, but may be necessary for transport into and out of the adsorbent micropores. To maximize adsorption storage of methane, it is necessary to maximize the fractional volume of the micropores (<2 nm pore wall separation) per unit volume of adsorbent. Macropore volume and void volume in a storage system (adsorbent packed storage vessel) should be minimized [18, 19]. 

Chemical Reactivity - Reactivity with Water Reacts vigorously, generating flammable methane gas Reactivity with Common Materials Will react with surface moisture to generate flammable methane Stability During Transport Stable Neutralizing Agents for Acids and Caustics Not pertinent Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

Skovborg, P. and Rasmussen, P., 1994. A mass transport limited model for the growth of methane and ethane gas hydrates. Chemical Engineering Science, 49(8), 1131-1143. 

Natural gas, found in geological accumulations, normally refers to the gaseous fossil-based equivalent of oil. Its composition varies widely, from high concentrations of nitrogen and carbon dioxide to (almost) pure methane. In general, it contains low concentrations of the higher (saturated) hydrocarbons, which influence the physical properties and may present condensation problems in high-pressure transport lines. 

See also Climatic Effects Fossil Fuels Gasoline and Additives Governmental Inteiwention in Energy Markets Liquefied Petroleum Gas Methane Natural Gas, Processing and Conversion of Natural Gas, Transportation, Distribution, and Storage of Oil and Gas, Exploration for Oil and Gas, Production of Risk Assesment and Management. 

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