Reactions to “Jet fuel from thin air”
The article “Putting the ‘sustainable’ in SAF” [May 2022] was excellent, and it shows that capturing atmospheric carbon dioxide is the key to the future of aviation fuel. In my own experience, though, each chemical step will add an additional cost to the fuel. In electrically synthesized fuel, the cheapest fuel is liquid hydrogen, followed by liquid methane and finally methanol. This, of course, does not include the cost of the hardware to use the fuel. Carbon capture will allow us to use fossil fuels beyond the 2050 net-zero deadline, permitting a slower transition to full sustainability. It is my hope that methane will find a niche as an aviation fuel. It is not perfect, but the question is what is the best choice? I discount biofuels as being too resource intensive. Perhaps I am wrong. There is a growing interest in ammonia as a jet fuel. Is this the best solution? It is time to explore our options.
James H. Sloan, AIAA senior member
Thanks for the interesting article on carbon neutral fuel in the May issue. Just one issue: There was no mention on where the electricity for electrolysis comes from. The sustainability loop has not been closed.
Rodger Herbst, AIAA member
Author’s response: Prometheus plans to obtain the electricity for electrolysis from renewable energy sources including solar and wind, so the resulting fuel would be carbon neutral. — Karen Kwon