Reply #82: Energy density by volume vs by weight [View All]

[kristopher]

First thing to understand is that H isn't an energy "source", it is a way of storing energy, comparable to a battery. By volume, H has a very low energy density - when it is in its normal gaseous state at sea level. When stuff a lot of it into a tank under pressure, it has a good energy density by weight - 60 pounds in a small tank.

The problem? It takes a lot of energy to put it in the tank. When a storage medium it is evaluated you look at the total efficiency of the process to get the energy to the end use. H has a far lower efficiency than batteries. That isn't relevant to a Saturn V rocket, but it means that in a car we can go nearly twice as far on the same amount of energy with batteries than we can with H.