Enron had much more efficient energy "storage" on paper than Tesla or even the most advanced oil companies. Plus it was much safer and less risky for the environment if there were thousands of barrels of volatile materials which only existed in a spreadsheet rather than all those cargo movements taking place in real life :\
Enron could fit more barrels on a piece of paper than their trading partners could afford to keep in a tank farm.
But when that spreadsheet sprang a leak, it all evaporated in the blink of an eye.