The bottom line on ethanol is a choice being made: feed the people or feed the machines?  In many 3rd world countries the price of grain for both human consumption and animal feed has reached the point where people are getting priced out of minimum caloric intake.  As the price of oil rises, the price a farmer can get for corn to be converted to ethanol increases in lock step with it.  The more corn you devote to the machines, the less left over for the people to eat.

About the only tie biofuels don't compete with the food market is with the waste products from some crops and wood chips and sawdust that are byproducts of the milling process.  In that case also though, you sometimes have a choice in land use made for wood over crops again because a better total price per acre comes from the wood+waste than from an alternative food crop.  Not always true, sometimes the land isn't suitable for a food crop but will grow some type of fiber crop.  One thing not mentioned is Lucid Dreams favorite plant, Bamboo from which you can get food or fiber.

With the steadily decreasing cost of solar PV and wind, combined with the fact it looks like a long haul before a grid connection is made for some plants, the cost of carbon free hydrogen is coming down fast and seems to me to be a better choice than biofuels for aviation at least.  Nuke seems better for container ships and tankers, we already use it for aircraft carriers and subs.  That is of course a huge increase in nuke plant numbers, and many of those ships are flagged with Libyan, Saudi and Iranian ownership.  Forgetting the politics though, it seems the better choice of alternative energy for this purpose.

RE