>> ajblair - Yes, the process is still pending.  POTUS46 and the IRA portion dealing with 45Z was outlined. Mitchell Hora IMHO has been the farmers voice to leverage his "Billion Bushel Challenge" to make certain the ethanol feedstock producers have a place in the still pending Farm Bill and the ethanol market.  You can find Mitchell's CI CHIT CHAT briefings on 45Z at YouTube: 

Mitchell's Brief just prior to POTUS47 swearing in Jan. 
https://www.youtube.com/watch?v=1bin9_0qXys&list=PLhKmZWrmatx4iQL_XHFEWsfvWiBUcc7C2  

Mitchells Brief a couple days ago Nov 3^rd.
https://www.youtube.com/watch?v=OY5Vkl1I8OE&list=PLhKmZWrmatx4iQL_XHFEWsfvWiBUcc7C2&index=1

>> plainsdrifter and Baby Robin - My error but your corrections are both right in the rules of thumb for the conversions. Good catch.   

The process to convert ethanol to SAF (Sustainable Aviation Fuel), often called the Alcohol-to-Jet (ATJ) pathway, involves several key steps: dehydrating ethanol to ethylene, oligomerizing ethylene into longer-chain hydrocarbons, hydrogenating the hydrocarbons, and finally, fractionating the mixture to produce SAF that meets jet fuel specifications.

This technology uses established processes to convert bioethanol, which can be sourced from various feedstocks like corn or biomass waste, into a jet fuel that can be blended with or replace traditional petroleum-based jet fuel.

Step 1: Dehydration Ethanol (\(C_{2}H_{5}OH\)) is first dehydrated, meaning water is removed, to form ethylene (\(C_{2}H_{4}\)). This is often done using a catalyst in a process like the one developed by Technip Energies' Hummingbird technology.

Step 2: Oligomerization The ethylene is then converted into longer hydrocarbon chains through a process called oligomerization. This step builds up the molecules to a size suitable for jet fuel.

Step 3: Hydrogenation The hydrocarbons from the previous step are then hydrogenated. This process uses hydrogen to add hydrogen atoms to the molecules, making them more stable and preparing them for the final fuel product.

Step 4: Fractionation The final product is a mixture of hydrocarbons. It is separated through fractional distillation to isolate the compounds that meet the specific quality requirements for jet fuel, such as kerosene.

This is similar to how crude oil is refined into different products.

Feedstock flexibility:  A key advantage of the ATJ process is its ability to use ethanol from a variety of sources, including corn, sugarcane, and even industrial off-gases or municipal solid waste after fermentation. This flexibility allows for the creation of advanced biofuels and e-fuels, depending on the initial ethanol feedstock.