The point is not an energy positive process. The point is a semi sustainable industry for making high density (liquid) fuels for the few systems that will need that energy density to continue functioning in an electrified future. The goal isn't "Don't burn anything ever". The goal is "Stop adding carbon to the atmosphere"
People talk about that concept like it's the future, but humans have been bulk producing a high energy liquid fuel with good stability and toxicity properties for millenia! The US produces enough ethanol to totally replace our entire commercial aviation usage right now.
Ethanol costs about $2 a gallon at that current industrial production level.
Actually that gives me pause. What stops anyone using it as a primary fuel right now if it's so cheap? I imagine the average airplane jet turbine has done a lot of testing on ethanol of course, and you always have to worry about your employees trying to drink your fuel then.
But my point is; We subsidize corn growth so that the USA will never, ever, ever experience a famine. That's the point. The corn will be grown regardless, and if there isn't a minor societal collapse that year, we should turn more of it into ethanol instead of corn syrup. Electrify agriculture and industrial process heat and you can also use that setup to essentially "Load shift" the high solar output in the summer into the winter.
Ethanol as a fuel is mostly a subsidy for US farmers. The net energy gain is low.[1] Ethanol plants need a lot of heat energy to process corn into ethanol. They don't burn their own ethanol for heat; they use natural gas or even coal.[2] If they made their own process heat, which they could, they'd use about half their own output. They wouldn't get the subsidy on that. So they burn other fuels to make ethanol.
That doesn't include the costs of farming the corn.
[1] https://energy.sustainability-directory.com/learn/how-does-t...
[2] https://www.researchgate.net/figure/Energy-use-in-each-of-th...