In general CO2 is a far less potent greenhouse gas than CH4, largely because there is already a permanent low level of carbon dioxide in the atmosphere. In a few decades the methane will oxidize to CO2, but in the meantime it’s like 40 times more potent. Better to burn it.
(Not sure if CH4 is inherently stronger than CO2 because of more possible quantum states, but I suspect atmospheric abundance is the main factor (without looking it up))
My layperson understanding was that the more atoms/bonds a molecule has, the less transparent it was to IR. Diatomic molucules like oxygen and nitrogen were pretty much transparent, molecules like CO2 and H2O were in the middle, and bigger ones like CH4 were less so.
I have a hazy understanding from the atmospheric radiation course I took a decade back, but if I recall correctly the vibrational states of a two-atom molecule are simply not at affected by infrared. To be a greenhouse gas, you need the, uh, rotational states provided by three or more atoms. Or something like that? I was always more of a dynamicist and barely scaped by in atm chem (it’s almost all free radical chemistry). Anyway you definitely need a third atom.
Burning it at the source means thatuch more gas will also be extracted and (ultimately) burnt for the other use.
2xNH3 -> 3xH2 + N2 is fine, only excepting that more NH3 will need to be made. In the future it will be made with wind or solar energy, but that is still a few decades off.
