Money is an abstraction of time and energy is how I see it. Michael also says something to the extent that we have money since we cannot just directly hand each other energy in a jar or something (or send with an email for that matter). Of course (a good) money also allows for energy to be stored and transmitted over time, which is why I think the battery analogy is great as well.
Discussion
It's not a bad analogy, but I don't think it's the essence. It creates the misunderstanding that all we need is PoW. Jason Lowrey the Pow Maxi is one of the most misunderstood.