In a Far Sci-Fi setting, how could you use energy as a currency?

I am in the process of making my 2nd sci-fi world.

Anyway, I was thinking about currency and started thinking. Throughout human history, currencies have been made of or backed by something that people found valuable, such as gold, silver, gems, etc. But within the bounds of a technocratic intergalactic empire, what would be the thing they find valuable but also had enough of to act as a currency. Energy! Within a sci-fi setting where if you want to do anything, you need help from machines, the most valuable resource would he energy, however, this isnt a tangible resource and it also brings into question of how it would be used.

If you power your machines with energy, you would be expending actual money to power that machine

But also if the system is based strictly on the amount of energy you have, couldn't you just get a generator and start producing your own energy?

Im just looking for people's thoughts on how this might work, its flaws and if there are any better systems that could be used for an almost entirely digital system.