"Unlike CH4 and CO2, ammonia is not a greenhouse gas. In the atmosphere, it quickly forms hydrogen bonds to water vapor and returns to the ground in alkaline rain. However, NH3 is toxic, chills its surroundings rapidly on vaporizing, and releases heat on contact with water. Engineering a safe fuel tank for an ammonia-fueled vehicle would be a key priority. Ammonia is an excellent material for hydrogen storage. ... the volume density of hydrogen in liquid NH3 is more than 40% greater than in liquid H2, and the comparison becomes much more favorable when one considers the weight of the required fuel tank and peripherals. Unlike H2 gas, ammonia explodes in air only over a narrow range of concentrations. Shipping ammonia from production site to point-of-use does not require a great deal of cooling or high pressure. Thousands of miles of NH3 pipeline in the US stand as evidence that reliable infrastructure for NH3 transport and storage has been engineered. In sum, liquid NH3 is not just an excellent hydrogen-storage material but also an ideal medium for moving hydrogenic energy from place to place."