> Ready combined-cycle gas generation capacity is more important, most places. Those will be incrementally converted to consume imported synthetic ammonia.

Synthetic ammonia that comes from where? Ammonia is currently produced by steam reformation, which emits CO2. You're talking about electrolyzing water to produce hydrogen, and using renewable energy to carry out the Haber process. Nobody is using this strategy of energy storage, so it's priceless in a very literal sense: there is no way to estimate how much such a system would cost. I'd take an expensive solution over a priceless solution any day.