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?
Money has three characteristics.
fungible; do you care if you get this 5$ bill or that 5$ bill? Do you can if you get this 25 cent silver coin or that 25 cent silver coin? If the answer is no then you have fungibility. This is why gem stones are not money. There is potentially a big difference between this diamond and that diamond even if they are both the same size.
easily subdivisible to facilitate commercial transactions. Fiat does this well. So did real money based on silver and gold. Coins of different denominations were issued and paper promissory notes facilitated larger transactions.
store of value. This is why iron is not a monetary metal but gold, silver, copper and nickel are. Iron rusts. The monetary metals fo not. You can put a gold coin in the ground and come back in 100 years. If you put 1 oz in the ground, you will take out 1 oz.
Energy does not store well. If you have. Barrel of oil and the barrel springs a leak, what do you have left?
Electricity? How do you propose to store it? A battery will have a loss over time, that breaks the basic definition of money.
Are you thinking of using calories as your unit of measure? If so, is 100 calories of oil equal to 100 calories of electricity which is equal to 100 calories in coal?