Storage Methods Compared

Mataial Gravimetric hydrogen storage amount (wt%) Storage temp. Storage (K) Pressure (Mpa)  

GNF = graphitic nanoflbre, SWNT = single-walled nanotube, MWNT = multi-walled nanotube.  

Method Gravimetric storage efficiency, % mass hydrogen Volumetric mass (in kg) of hydrogen per litre  

None of the methods for storing hydrogen outlined in Section 8.9 is entirely satisfactory. Other approaches that are being developed rely on the use of chemical hydrogen carriers . These could also be described as man-made fuels . There are many compounds that can be manufactured that hold, for their mass, quite large quantities of hydrogen. To be useful these compounds must pass three tests  

It must be possible to very easily make these compounds give up then-hydrogen - otherwise there is no advantage over using a reformed fuel in one of the ways already described in this chapter. 

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From the table, we can see that the first-order method usually requires fewer floating-point operations and memory storage if compared with the Primal-Dual interior-point method. The unique drawback of the former method is that we cannot guarantee a convergence of the method in a certain time frame. 

Storing H2 in aqueous NaBH4 solutions compares favorably to other H2 storage methods. For example, the volume required to store 5 kg of liquid H2 in cryogenic containers is —110 liters. In pressurized tanks, storing 5 kg H2 at 34 MPa (5000 psi) requires 220 liters. However, storing 5 kg of H2 in 35 wt % NaBH solutions requires only 65 liters. 

Relatively high cost as compared with gaseous and liquid hydrogen storage methods. 

Among the many candidates of hydrogen transportation or seasonal storage methods, the H2 evolution from cyclohexanes at the demand site and the reverse reaction, the hydrogenation of benzene, at the supply site offers the advantages of safe and commonly used transport at ambient temperature in chemical tank ships or trucks and mild reaction conditions. Cyclohexanes have a hydrogen density and content comparable with metal hydrides [8]. Methylcyclohexane is the choice of preference, since unlike benzene, toluene is not carcinogenic. 

The storage efQciency compares well with other systems. This method may well have some niche applications where the disposal of the hydroxide is not a problem, though these are liable to be limited. 

Acoustic emission events can be detected on loading a component, but the type and number of events are difficult to relate to visible damage. One test method for chemical storage vessels compares the... 

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