Question

Why is methane so expensive to harvest as a nonrenewable energy source?

Answer 1

Answer:

Methane is found deep in the Earth's crust, which makes it difficult to harvest

Explanation:

According to the Scientific American:  "With drillers tapping into massive stores of natural gas across the United States, scientists are researching ways to capture it more effectively". On the same article, you can find that: "Energy companies are looking for a cheap way to separate these gases to yield a pure methane stream". So it is hard and expensive to harvest methane, even though drillers keep finding it.