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?
It's not a question of whether or not it can have intrinsic value. It can and does. The question is, can gathering and storage infrastructure and technology fall behind our requirements for it sufficiently that it can be traded in a meaningful way. We currently trade it at a 20 cents per kilowatt hour or so on average. That price will only go down as we leave behind the corporate chains that have hold on it.
Cold Fusion technology has existed for over two decades in an experimental (but usable) format. It has been suppressed by the PTB because to release it to the masses would destroy the corporate stranglehold on energy. That is not the only possible hidden energy tech, just the only one I can say for sure exists.
Cold Fusion allows for all of our current energy requirements to be met for a couple dollars worth of fuel a year. That includes us using it for "flying cars" and whatever else you want. If energy is that cheap, how can it be used as a currency unless we find a need for many orders of magnitude more energy per capita (everyone has their own personal wormhole generator for example).