What an absolutely stupid comparison.
You cannot compare $/0.5 gallon to $/million BTU. It’s just a coincidence that the numbers come out around the same.
The author should try $/microliter versus $/Watt-hour to see if they are similar.
I’m guessing the author isn’t an engineer nor did he study Dimensional Analysis.
</pedantic>
I thought it was a stupid comparison too. One BTU of natural gas is about 1 cubic foot. One million BTU would be about one million cubic feet. You could compare to one million cubic feet of water, but one is a gas and one is a liquid. It is still comparing apples and antelopes.