Consider the market for natural gas. In this industry, low average costs are obtained only through large-scale production. In other words, the initial cost of setting up all the necessary pipes and hoses makes it risky and most likely unprofitable for a competitor to enter the market.
A monopolist, unlike a competitive firm, has some market power. It can raise its price, within limits, without the quantity demanded falling to zero. The main source of a monopolist's market power is barriers to entry - that is, obstacles that make it difficult for competitors to enter the market. Which of the following best describes the source of the monopolist's market power in the preceding scenario?
a. Economies of scale
b. Innovation
c. Hard to duplicate resources

Producing natural gas is very expensive and requires a large investment. The costs and risks of the processes involved in the upstream and downstream of natural gas discourage competition. Besides requiring a large initial investment, a drilling company can never be 100% sure that they will be able to find and extract natural gas or petroleum. So besides having to spend a lot of money, you are assuming a great risk.

Even if a competitor finds natural gas, in order for the downstream process to be profitable, they must be able to extract a large volume to achieve economies of scale.