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For comparison, from wikipedia:

Gasoline: 12,889 Wh/kilogram

Diesel: 13,333 Wh/kilogram

Lithium Ion battery: Ranges from 100 to 243 Wh/kilogram.

Even when you consider that something like 50% of the energy in gasoline is lost to waste heat in a typical internal combustion engine, it's still a huge difference.

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Hydrogen: 33,300 Wh/kg (compressed: 39,443 Wh/kg)

The problem is that you need a big heavy tank to keep all of the Hydrogen molecules from escaping, especially if you're keeping it under pressure. Hydrogen is much more problematic to work with.

But look at energy per volume [1]:

Diesel: 35.8 MJ/L

Hydrogen: 9.17 MJ/L at 700 bar (10,000 psi).

It will require a tank of 4x the volume for the same energy which comes with many additional challenges. Plus, a tank that can withstand 700 bar will have to be extremely strong and heavy which hurts your energy/mass ratio.

1. https://en.wikipedia.org/wiki/Energy_density#Energy_densitie...

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