NH3 is easier to make into liquid. CH4 requires cryogenic temperature and high pressures to liquify. For that reason I think that NH3 will dominate in the lon

NH3 is easier to make into liquid. CH4 requires cryogenic temperature and high pressures to liquify. For that reason I think that NH3 will dominate in the long run. But, CH4 can be made passively from organic waste so it might eek out an edge. It would be interesting to see the energy cost breakdown for production, storage and transport of both. Methane already has a place in our energy economy. I speculate it will lead over NH3 for quite awhile.