It's disputed whether even modern ethanol production is energy-positive. But trying to start an entire biofuels production chain from scratch would certainly not be net positive, as you would need to already have mechanized agriculture and a petrochemical industry to get that efficiency.
Coal liquefaction would probably be superior to biofuels, as it seems we will give up using it before it is depleted.
Coal liquefaction would probably be superior to biofuels, as it seems we will give up using it before it is depleted.