The right price of oil

"Recently, I started asking people important questions - as expected, folks don't know jack-shit. Not even Kunstler knows -
How much energy do you get out of a barrel of oil, provided you use it properly (in joels, or in KW, I don't care).
How many trees (how many pounds of wood) would you have to cut down and burn in order to get the same amount of energy?
How many pounds of coal?
How much energy does an eight-car passenger train requires to travel one mile?
Knowing the answers would put things in perspective, at least for me. But you know what? Even f**cking scientists don't know shit anymore."
I humbly try to give an answer.
It looks to me that the answer to the question depends on the beholder's needs.
If he has a lot of oil or coal or whatever to sell and doesn't care for its price, then the output is negligible.
It doesn't matter how many trees, the important is that everybody burns them.
But if the price has to be higher, then there comes the shortage of oil, trees and coal...
People may not know the value, but certainly know the price...