Hydrogen energy density

Pout (hydrogen production rate) x (hydrogen energy density) Pjji solar flux integrated over illuminated area... 

Hansen [137-139], and later van Krevelen [114] proposed the generalization of the solubility parameter concept to attempt to include the effects of strong dipole interactions and hydrogen bonding interactions. It was proposed that the cohesive energy density be written as the sum of three terms, viz. 

It must he recognized, however, that hydrogen usage for transportation will always create a trade-off between energy efliciency (fuel economy) and energy density (range), whereas this trade-off is non-existent for other applications. 

Aprotic polar solvents such as those listed in Table 8.1 are widely used in electrochemistry. In solutions with such solvents the alkali metals are stable and will not dissolve under hydrogen evolution (by discharge of the proton donors) as they do in water or other protic solvents. These solvents hnd use in new types of electrochemical power sources (batteries), with hthium electrodes having high energy density. 

Liquids without dipole moments (alkanes) have quite low cohesive energy densities, whereas hquids with dipole moments or hydrogen-bonding groups have high cohesive energy densities. 

Figure 3.6 Energy density map for the difference between a hydrogen molecule and two hydrogen atoms. The solid lines indicate increased density and are marked with labels indicating atomic units. The dashed lines indicate decreased density. Two dots indicate the positions of the hydrogen atoms in the molecule. They lie 0.74 Angstrom units apart. After Bader and Henneker (1965).

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