In the best case scenario, how much hydrogen can we extract from a?
Pretty straightforward calculation. Compare the density of each substance with its molecular formula and the atomic weight of the other constituents.One cubic meter of water (H2O) has a density of 1000 kg/m3. The molecular weight of water is 2(1) for Hydrogen plus 1(16) for the oxygen = 18 g/mole As you can see, the Hydrogen is one ninth of the mass of the water, therefore the Hydrogen in 1000 kg of water is 111.1 kg The density of LNG is a little trickier because it varies with the temperature much more than water does. References give a range from 410 to 500 kg/m3. Lets see what pops out when assume 410 kg/m3. LNG is mostly methane, CH4, molecular weight 4(1) plus 1(12) = 16 So Hydrogen comprises 25% of the mass of any volume of methane. .25 x 410 kg = 102.5 kg of Hydrogen in a cubic meter of LNG, at a minimum. Alternatively, .25 x 500 = 125 kg. So you can see that the amount of Hydrogen per cubic meter is roughly the same for LNG as for water.Now the efficiency of deriving the Hydrogen from the LNG vs from water is a different story.