Why not pelletize Methane which is reformed off Natural Gas derived from a Coal source so that it can fuel a furnace by shooting the pellets into the furnace to produce steam, collecting the pellets each day from a vehicle would make the distribution to a collection point ever so useful when a fleet of ten or more taxi cabs or a truck fleet contributes to the pellet distribution. If and when a Methane Fuel-Cell is provisioned this pellet form would then be like a Hydrogen form for refueling issues. Creating small frozen pellets would enable petri dish storage in cylinders and through automation these are extracted one at a time. Even a donut style would suffice better.

Ammonia
Fuel Density: 0.604 g/cc
Fuel Freezing Point: -78 deg C
Fuel Boiling Point: -33 deg C
Ammonia is toxic, and will dissolve easily in water
Ammonia does form flammable and explosive mixtures with air
Anhydrous Synthetic Ammonia is cheap per ton

Liquid Oxygen as a Oxidizer
Oxidizer Density: 1.140 g/cc
Oxidizer Freezing Point: -219 deg C
Oxidizer Boiling Point: -183 deg C
LOX is obtained from air by fractional distillation
LOX is stable but mixtures of fuel and LOX are shock-sensitive fuel vapours that can be exploded by static electricity, electric spark, or flame.
Cryogenic not suitable for military uses where storage of the fuelled missile and quick launch are required
See the United States by Military Specification MIL-P-25508

Rocket Engines are not allowed on Americas highways, classified as illegal. Ammonium Hydroxide is Severely Poisonous, may be fatal if swallowed or inhaled (higher concentrations can cause burns, pulmonary edema and death), and vapor causes burns to every area it is exposed to, Extremely Corrosive with a rating of 4. Hydrocyanic Acid (or "Hydrogen Cyandide") (HCN) can be commercially produced by reacting Ammonia with Natural Gas (Methane) and an Oxygen-containing gas at an elevated temperature in a converter in the presence of a suitable catalyst. The exit gas from the converter contains unreacted Ammonia together with small amounts of Oxalic Acid and Formic Acid (or precursors of Oxalic Acid and Formic Acid). The Oxalic Acid and Formic Acid end up in the aqueous solution, where they
are converted to oxalates and formates. A concentration of oxalate greater than 1% and a concentration of formate greater than 3% are undesirable causing a overhead expense to purge it. The oxalate and formate compounds present in the
ammonium phosphate solution are continuously decomposed to carbon dioxide and hydrogen using electrochemical cell. Decreasing the concentrations of formate and oxalate compounds should enable the use of increased concentrations of ammonium phosphate in the ammonium phosphate solutions, and hence an increase in the capacity of the process.

A Rocket Engine use was for the XLR-99, USAF Rocket Engine First Stages and is Out of production. The X-15 Rocket Engine use as first stage options were, Bell XLR81-BA-1, Aerojet XLR73-AJ-1, and the Reaction Motors XLR30-RM-2 while the XLR30 rocket engine to be inadequate and a new design was initiated and designated as the XLR99-RM-1 Rocket Engine. The XLR-99 was used in the X-15 manned research rocketplane. The X-15A improved the version in a stage two engine use, while the X-15A-2 added another stage for the LOX/Ammonia use in the improved XLR99. The LR30 Rocket Engine was cancelled in favor of the XLR99. The flow rate of more than 4,500 kg per minute for both propellants were liquid oxygen (LOX) and Anhydrous Ammonia.

XLR-99, USAF
Thrust(vac) = 262.400 kN
Thrust(sl) kN = 227.300
Isp = 276 sec
Isp (sl) = 239 sec
Designed for = First Stages
Status = Out of production

Sadly Americans have been tricked out of the easily available 40 % fuel savings offered by converting to proven Euro-Diesels, and are being weaseled around the obviously workable Euro-Diesel - Algae based bio-diesel solutions! What makes developmentalists think for one New York minute H2 will have any better success? The powers that be in this country have deemed gasoline in cheap low compression short lived inefficient engines as the way to go, and the Exporters to America, the Germans, Japanese, and South Koreans oblige their customers in this respect and send us gasoline engines where turbo bio diesels could be ordered up. As long as oil is profitable for certain large controlling investment groups, we in America will burn gasoline in ever bigger vehicles, and damn well be controlled and pay through the nose for it, and we will not make changes! The "Status Quo" in America is very comfortable for the moment, and it is the sincere wish of our oil suppliers, that we will accommodate rises in price as they come along, growing accustom to larger shares of income going to them, as prices rise to meet their own domestic needs - and we do this - in the face of even the obviously simple turbo, bio, Euro-diesel 40 % savings in imported oil to our country! America is a Saudis and OPEC controlled, Chinese owned, marketplace, Americans buy what the wild eyed, well commissioned advertising propagandists dictate, and we end up with rows of McMansions, foreclosed, rotting and useless, because of our vulnerability, our simple minded follow the leader logic, and our advertising infection to have the newest, biggest improved, better, whatever, before our neighbors, to give us momentary fleeting feeling of accomplishment and superiority, before the next better, newer, more improved, Bull Shiite comes along! To go from gasoline to H2 will require a lot more than technical advances in America! Marketing the change will take more cash than researching the discoveries, unfortunate but true in our ever more dumbed down corporate loving, illogical comfortable sucker society!