When they stop the subsidies, it will die out...
What subsidies? All subsidies targeted at ethanol have been eliminated for a few years now. Now, oil.... they still get some subsidies that they have gotten for over a century. Why are you not crying foul over the oil companies getting taxpayer money? Subsidies are actual money transfers to an entity. There is no such animal for the ethanol folks now, and hasn't been for a few years now.
Since ethanol has no more subsidies, and it is selling for a roughly a dollar less on the Chicago Board of Trade (you know., commodity central) than gasoline is, then the ethanol folks must really be losing their shirt. And even with government mandates, the price of the stuff is still what it is on the board of trade. The producer is only going to get what the market says they are going to get.
Now if you think a reduction in tax for ethanol producers is a subsidy, that would be wrong. It is called cost of doing business and an expense. All expenses are written off. Be it those guys or the local plumber, or any other business. It is done on the schedule C on the 1040. But I would go along with not letting ethanol producers get to write off their business expenses, if everyone also gives up their dependent deduction, child care tax credit, mortgage interest deduction, medical cost deductions, etc, etc. They have a name for that. Wait a minute, it will come to me..... oh yeah, it is called the Fair Tax.