[skybrian]

Yeah, the comparison feels a little off, but you could make a direct comparison to producing ethanol from corn or sugar cane.

And historically, it is true that agriculture was the source of most wealth, including both food and energy. Consider growing hay -> feeding pack animals -> transportation. Also, using firewood to generate heat, large amounts of which were needed to for expensive processes like iron smelting. (Not to mention human labor.)

Nowadays it's the other way around, agriculture requires energy inputs for things like fertilizer.