Simmons mentioned ammonia, and that got me thinking... I've been reading for years about the possibility of using ammonia to replace the electrical grid, at least over long distances. I know our grid wastes a lot of power. Would an ammonia infrastructure be more efficient? Realistically, how much energy would be gained? Is it possible to retrofit our existing nuclear reactors to produce ammonia in addition to electricity? Would that be more efficient?

the question has been studied and answered a quarter of century ago, see

Green, L. Jr., 1982 "An ammonia energy vector for the hydrogen economy".
Int. J. Hydrogen Energy, pp.355-359, Vol 7, No. 4

things may have changed a bit but the big picture still holds.