According to scale-up calculations, using an in situ ammonia
electrolyzer on board will allow a HFCV to travel 483 km between
refueling by storing 203 L of aqueous ammonia. At 0.36 US$ kg−1
of ammonia, the cost of producing hydrogen on board is 2.02 US$
The price is right for the hydrogen, but there's a problem.
The sticking point in my opinion, is the cost of the electrolyzer itself. It is estimated from the paper that an appropriate sized electrolyzer will cost over 32000 dollars at then platinum prices that were half of today's price. It is quite clear to me that the price of platinum and platinum group metals will have to come down somehow, or some other way must be found. One way to lower the price of platinum is to mine a lot more of it. Thus a source of abundant platinum must be found. That source can come from outer space.
There may be a way to reduce these numbers, but it is clear that the numbers don't work without more platinum. That is my opinion.