Storage of methane

Low pressure storage of methane Desiccant cooling (open-cycle air conditioning)... 

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]. 

The main hazard is that of flammability. The following precautions supplement those in Table 9.3 for the storage of methane gas cylinders ... 

Energy storage, i.e., storage of methane and hydrogen, has attracted much interest, particularly for onboard-vehicle applications. Activated carbon has been the most promising candidate as the sorbent for both methane and hydrogen storage. 

Table 1 summarizes the results of the N2 and H2 physisorption measurements of the materials analysed. All samples are highly micro-and mesoporous carbon materials. In our experiments four samples of carbon Busofit-AYTM (1 - 4) and three samples of wood-based activated carbon (5 - 7) obtained by new technology were investigated. The activated carbon 207C (8) is made in the Great Britain from coconut shell. Samples 9 and 10 - granular activated carbons, specially developed for effective storage of methane. 

The storage of methane as hydrates offers a potentially vast natural gas resource. As to the question of how much hydrate there is right now, there is no definitive answer. However, the worldwide amount of carbon bound in gas hydrates has been estimated to total twice the amount of carbon to be found in all known fossil fuels originally on Earth. Additionally, conventional gas resources appear to be trapped beneath methane hydrate layers in ocean sediments.22... 

Figure 10. Experimental equipment to study high pressure storage of methane 1- container with adsorbent, 2-methane container, 3 - gasmeter, 4-vacuum pump, P- pressure transducer, T-resistance thermometer.

The preparation of binderless carbon monoliths by carbonizing conformed cellulose and then activating by reaction with carbon dioxide has already been described (Inomata et al., 2002). Physical activation of such monoliths requires a reaction with carbon dioxide inside the monoliths. Severe diffusion restrictions may apply to such a procedure. Monoliths, by not being a powder or granular, are of high density and have relevance to adsorption processes in limited volumes as, for example in storage of methane. 

FIGURE 3.3 Storage of methane, ethane, propane, -butane, and -pentane in aqueous solutions containing (20) +. Concentrations of guest molecules were determined by gas chromatography after incubation of sample solutions for 24 hr in DjO (3 mL) in the absence (open bars) and presence (closed bars) of (20) (2 mM) at pD 7.4 and 25°C for 10 hr in glass bottles under ambient pressure (1 atm). 

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