Hi Dan,
Good question! For the fuels sector, we evaluated hydrocarbon fuels that could feasibly derived from CO2 and biofuels. In other words, we evaluated fuels that could, at some point, be economically sourced from waste carbon feedstocks (like plant residues) or near pure CO2. While coal could be displaced by novel carbon capture technologies coupled with energy systems such as the Allam Cycle, coal cannot be produced from waste carbon feedstocks.
Thanks for reading,
-Rory