It would be good to see a techno-economic analysis of this. For instance, taken to the limit, if solar were free what would be the CAPEX and OPEX to produce the ammonia? In addition, the plant to consume the ammonia to produce electricity would not be free.
OK, so it requires a plant of fuel cells. And the cost per kW (i.e. discharge capacity) is? And it requires some facility to produce the ammonia; what is the cost per kW of electricity consumed, and at what efficiency?
Numbers would help to assess the proposal, given the claim that a halving of the cost of electricity from solar would make all the economics for ammonia work.