Why Ammonia

Electrification is typically the best overall solution to decarbonize use cases where it can reasonably compete with hydrogen, e.g. light duty transport, heat pump heating, and short term grid storage. However, power grid limitations and battery cost/weight/volume become the major limiting factor for many applications in heavy industry or involving long-distance transportation.

Compressed hydrogen (CH2) is a relatively efficient way to store energy, however its incredibly low volumetric density limits it to on-site or short-distance applications.

Liquified hydrogen (LH2) requires extreme cryogenics (-252C or 20K) and has traditionally only been used in the space industry or in laboratory settings. While LH2 is technically feasible, its cost and complexity make it less attractive than ammonia in almost every use case.

Liquid organic hydrogen carriers (LOHC's) are easier to handle than ammonia. However, compared to ammonia the process is less energy efficient (to embed and extract hydrogen), has far less optionality (LOHCs have no intrinsic value as a chemical), and remains less mature as a technology.

Methanol and other biofuels are popular as they are relatively easy to handle and are more of a "drop in" fuel than ammonia. However, biofuels face a number of production challenges, principally that they will always remain more expensive to produce in a truly zero-emission fashion than green ammonia due largely to them requiring a carbon atom.