Everyone please remain calm. (FAHAD SHADEED/REUTERS)

With domestic electricity demand rising 10% per year in Saudi Arabia, the kingdom now devours more than a quarter of its oil production—nearly three million barrels per day. International Energy Agency figures show that Saudi Arabia now consumes more oil than Germany, an industrialized country with triple the population and an economy nearly five times as large.

Worries about Saudi excess capacity are one reason why Iran-related tensions have driven crude prices up so high. By one estimate, this spare capacity could vanish entirely by 2020. If that happens, oil prices will get seriously volatile.