And, as I remarked above, when Hubbert wrote his original paper about “peak oil” (at least, I think the thing I saw was his original paper), he explicitly said that coal can be used to make oil and gas, and that therefore diminishing oil extraction doesn’t have to mean no more oil.
It is possible to produce oil from coal. It’s not a new process, Germany used it widely during WW2 as it had little access to “regular” oil.
And, as I remarked above, when Hubbert wrote his original paper about “peak oil” (at least, I think the thing I saw was his original paper), he explicitly said that coal can be used to make oil and gas, and that therefore diminishing oil extraction doesn’t have to mean no more oil.