Reddit reviews Alcohol Can Be a Gas!: Fueling an Ethanol Revolution for the 21st Century

I don't have references for this, but most farm animals require about 30% of your cropland for their own food. However they provide manure so it makes nutrient cycling a lot easier.

For example see: John Seymour's Book Where he goes on about how awesome cows are just for the manure they provide.

I was reading in David Blume's Alcohol can be a gas That you can use only 10% of your land to produce the Ethanol needed to farm it. However i don't know if this has been studied in practice.

Both methods are more labour intensive, since animals need care and making your own moonshine almost requires learning a new career. This will require raising farm wages to entice people out of the cities (or desperate people) and will not favour megafarms as they are far more dependent on capital-intensive methods.

Related:

http://www.amazon.com/gp/aw/d/0979043778?pc_redir=1413519727&robot_redir=1