[aydyn]

It doesn't make sense to look at that in a vacuum. Energy transport over wire via electricity is much "denser" than transport via liquid or gas.

"It depends" is the correct answer, but the equation is shifting quickly towards solar + electricity.

[jacquesm]

You're the one looking at it in a vacuum. Engineering is all about looking at it in context and the main context where density of energy is important is in vehicles of all shapes and sizes. That's where the rubber quite literally meets the road. You can then theorize about what the 'weight' of the electrical energy is but it is pointless: the weight of container dwarfs the weight of the energy carriers (effectively the electrons) themselves. In the case of fossil fuels the ratio is more balanced, the container will weigh a couple of kilos and the fuel will way a bit more (say 10:1 or 20:1). So to compare the one with the other we weigh the batteries and ignore the electrons and we then compare that with the fuel because that is the dominant factor.

Solar + electricity are not directly suitable for powering electric vehicles, that's where the batteries come in.

Comparing apples (transport of electricity via wires) with oranges (transport of energy via liquid or gas) misses the elephant in the room: you are not going to be able to use those electrons without a suitable temporary storage medium unless you plan on carrying a very long and impractical extension cord behind your now very light EV.

[aydyn]

This discussion is not solely focused on EVs.

[jacquesm]

The moment someone mentions energy density you can bet they are talking about vehicles and not about stationary stuff.

[aydyn]

That is just retconning the discussion, please go back and check.