If ethanol were readily available, there would be no compelling reason to make DME from it.   Ethanol, unlike methanol, is not that toxic at least diluted.  One might get drunk from contaminated water supplies but not blinded.

I hear a lot about ethanol, but I'm either agnostic or skeptical.   The downside is always going to be the lack of a continous process - the necessity always of having a batch process - and the water intensity.

I think supercritical water oxidation (SWO) of biomass would be a superior idea to fermentation - if we want to have biomass derived fuels.   This idea lends itself to DME.

SWO would probably also be batch processing, but reactor time would be much shorter.   It also affords excellent opportunities for cogeneration.