What is the unused world oil production capacity called?

• A. Spare Capacity
• B. Idle capacity
• C. Reserve capacity
• D. Peak capacity

Answer: (A)

The main concept here is spare capacity—the portion of world oil production that isn’t being produced right now but can be brought online quickly to cover disruptions or unexpected demand.

Spare capacity serves as a buffer in oil markets, allowing producers—often major exporters—to raise output within a short time frame to stabilize supply and prices if an outage occurs or demand suddenly rises. It’s specifically about ready-to-use capacity, not just any unused facilities.

Idle capacity is simply unused capacity without the explicit role of being quickly deployable; reserve capacity isn’t the standard term for this market buffer, and peak capacity refers to the theoretical maximum output under ideal conditions, not the available buffer that can be mobilized. So the best term is spare capacity.