If I have this right, Ammonia is 2x more expensive than petrol per tonne, and has half the energy density of petrol, so it seems to be 4x more expensive? I am

If I have this right, Ammonia is 2x more expensive than petrol per tonne, and has half the energy density of petrol, so it seems to be 4x more expensive? I am not sure how to compare with hydrogen, as you say costs for it are in storage and transportation