As energy has a usefulness and intrinsic value that even gold lacks. It could be traded anonymously like cash like batteries as dollars or as energy storage and quick and efficient transfers becomes smaller and more convenient. Im thinking specifically electrical energy with batteries and capacitors but even gas could be used.
It could be created by individuals with solar panels or bike mounted generators. It could be stored as potential energy in large amounts as heat or pressure and then converted back to electrical energy when needed. It could be networked for large transfers. There could even be large banks that hold energy as a business, but they would not be able to lend more than they hold. Private individual energy storage would be the most secure from government or other seizure obviously.
Wheres the flaw?
A very important property of money you are missing. It never has intrinsic value. It is an accounting mechanism. That is all. The salient point is what governs and restricts that accounting mechanism. It always has value only because 2 parties accept that it represents value.
Barter, on the other hand, is the exchange of intrinsic valued things that people need for daily function.
But energy is very hard to barter directly, because it can not be easily transported. Even if stored in batteries or hydro (with terrible efficiency losses mind you), you can not easily move it from one place to another. Oil is probably the best energy storage mechanism that can be easily transported, and thus, bartered.
Im thinking small scale to start with until tech catches up. Start with farmers markets and garage sales or places where bartering might already be happening. Large purchases like a car or house would be difficult currently and maybe more easily done with oil.
The point is, the energy in your battery (and the battery itself) in your pocket does have value and is currently transportable. If i anticipate tech to get better and energy density, storage efficiency, and transfer efficiency to all improve. This could be a way to get away from fiat currency and have something that wouldnt be vulnerable to market crashes.