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Comment by darquomiahw | Hacker News Reader

This type of process has already been developed industrially: https://en.wikipedia.org/wiki/Birkeland%E2%80%93Eyde_process

The trouble is that it is inefficient and will ultimately release some NOx compounds into the atmosphere since the conversion rate is not 100% to HNO3. I'm surprised there is not a single mention of this process in their paper.

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The process you mention is for a "hot plasma" formed by electric sparks. Presumably this companies technology uses "cold plasma" aka non-thermal plasma which is significantly more efficient and more selective toward HNO3. Heres a good review paper: https://link.springer.com/article/10.1007/s42768-021-00074-z

Here's another interesting one: https://pubs.acs.org/doi/10.1021/acssuschemeng.9b04997

There is still some NOx production, but likely low enough enough concentrations to be filtered.

I'm sure there are some optimizations that can be done on the process but yeah, it isn't new. I don't think the NOx issue is significant because you can sequester them, but it does add to the expense and lower the efficiency(unless you have a source of animal urine and can use the urea maybe?).

Is the efficiency difference between it and the Haber-Bosch process small enough to be made up by the lack of transportation?

I wonder if the nitric acid is a benefit in places with alkaline soil and water chemistries?

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