Okay. Planes was a bit tongue in cheek from me.

The central point was that syngas, as it stands today, only really works if you have a concentrated carbon source due to the infeasibility of direct air carbon capture.

Meaning, for aviation to be freely able to release its previously captured carbon to the atmosphere we need a source for it. Capturing the exhaust fumes from a coal plant is just fossil emissions with extra steps.

One source could be biofuels and biogas from waste. But is that enough to run all airtravel on? Likely not. And if the carbon source is biofuels then we might as well just skip making syngas and run the airplanes on it directly.

The aviation industry have enormous problems to solve, and for it to work I think direct air capture needs to be solved. Or they need to manage with liquid hydrogen or ammonia. Come to think of it; ammonia and an airplane crash sounds like a terrible recipe...

For maritime shipping they alreay have engines running on hydrogen, methanol, syngas, syndiesel, ammonia and whatever else that is liquid at any temperature and makes a bang. They also have the space to install carbon capture systems if they choose to go down carbon based fuels allowing them to not be reliant on direct air capture.

This is why they truly like ammonia. It is a liquid with similar nastiness properties as methanol which they know how to deal with. Nitrogen is trivial to capture and it makes a bang when ran in an engine.