one of the most cost effective way for transport is pipeline. ammonia can be transported via pipeline. can nitric acid or ammonium nitrate be transported in that way?

Building pipelines or storage is a huge barrier to entry. I believe just shipping it via boat/train/truck(in that order of preference) is good enough to get things started while still making environmental sense.

Yes, you could ship ammonium nitrate via pipeline in solution if you wanted to, but it probably makes more sense to ship the ammonia without excess water if you have access to a pipeline.

the question is for how long? performance enhance drug can do wonders for a short while but can kill the taker in the long run. farming sinks carbon but ammonia interacting with soil produces N2O which is a few hundred times stronger a GHG than CO2.

I don't see this debate being settled in the near future. In the mean time, is it better to fix nitrogen using renewable energy sources instead of natural gas when and where it is practical?

N20 is also produced by nitrogen-fixing bacteria, urine, manure etc. Most if not all sources of N-fertilizer share this problem. Are you sure it does not just come down to how much N-fertilizer you use and how timely the application is?(fertilizer application should be scheduled according to the specific needs of the plant and in the nescessary amounts for best effect)?

the point is that there is nothing in higher and more critical demand than renewable, clean and easily transportable liquid fuel. ammonia can play a much bigger role in this way than anything else.

All the more reason you should take the ammonia and use it instead of converting it back to electricity.

the sooner to stop using hydrocarbons for fuel or fertilizer feedstock the better.