i understand that we mine it already, but you need to look at how much it will cost to build a refinery. that cost, opperating costs, and the cost of workers needs to be covered by their selling price.
you can take a guess and say it costs as much to build and run one of these joints as it costs to run a conventional refinery. so that brings us back to “how much does it cost to refine x amount of oil to 1 gallon of gas?”. without knowing that, the current cost of coal, or how much coal is needed to make 1 gallon of gas this is kinda pointless. if coal is cheap (which i am sure it is) but it takes 50 lbs to make 1 gallon of gas, then it may not be worth it.