Biofuels are a sideline show. There's never going to be enough supply to satisfy demand, and when the "total" environmental impact is considered, there's a very, very negligible gain over decades (best case).
This video has been posted before but it brings FACTS into the conversation that are ignored by many.
Summary: BEST CASE SCENARIO is that using E10 would reduce a carbon footprint by a total 2% over 28 years. (not 2% per year; that's 2% total over 28 years). The more realistic estimates would likely go negative in effect; there's no benefit whatsoever.
In the video, he does not address the E85 topic, but we can extrapolate some reasonable conclusions ...
If we switched to E85 for our entire SI fuel supply, the demand for ethanol would be so shockingly high in volume that we would have to cut/slash/burn down every forest and turn over every single acre of grassland, releasing many, many more times (exponentially more) of carbon INTO the air, just to get ethanol source to be able to be grown.
E85 is great for racing engines that specifically need the octane to run really high compression ratios and/or very high density pressures (forced induction). Other than that, E85 is a Ponzi scheme (literally) where we pump more carbon INTO the air than we can reasonably remove in decades of capture/recycling.