https://www.reuters.com/business/environment/us-corn-based-ethanol-worse-climate-than-gasoline-study-finds-2022-02-14/
I could see how vested interests would really not like this study, but it isn't at all a surprise. Similarly, California's carbon offsetting program may actually be increasing methane emission, by supplementing milk production.
I've always thought that the ethanol requirements were primarily a subsidy to corn states. I was surprised by the USDA estimate (though, it is the USDA... it's their job to make corn farming great again).
Looking at the USDA study, though, I see that it takes into account things like the fact that the ethanol requirement in fuel will push up the price of corn which will make it more expensive to feed cattle which will push up the price of dairy products and that will reduce GHG (but it is offset by an increase in beef cattle because they can be pastured and not fed corn or something like that).
I'm not sure that's the best way to analyze that. I can also make dairy more expensive by putting a price on carbon or getting rid of dairy price support programs or many, many other methods aside from actions that artificially increase demand on corn.
Debbie says both of these studies were highly influenced by their funding sources.
>make corn farming great again
I see what you did there.