Matt, Nathan Wilson is an engineer who often contributed posts on The Energy Collective looking at the possibilities of ammonia as a liquid fuel. In our many, many discussions on the subject we discovered there are some fundamental reasons - physical, environmental and economical - why ammonia will probably never see widespread adoption as a transportation fuel:

• Energy density. In simple terms, there's not as much energy available from ammonia (NH3) as from hydrocarbon-based fuels like natural gas (CH4). The energy comes from breaking the bonds connecting hydrogen to either nitrogen or carbon. Ammonia has three, methane has four.
• Competition. fossil fuel companies don't want ammonia because it would compete with their core product line of hydrocarbon-based fuels. Nitrogen is made from liquefied air - a source available to anyone.
• Toxicity, and smell. Ammonia is toxic, and consumers tend to reject any product which smells bad - a simple truth of marketing.
• Compatibility. The classic "chicken-egg" problem of hydrogen applies to ammonia. Consumers won't buy ammonia-powered vehicles without convenient locations to refuel them; fuel manufacturers won't build refueling stations where there aren't consumers to buy their fuel.

Powering transportation with liquid fuel was a direct result of the discovery of oil in 1859. Though some contemplate the production of green liquid synfuels using either nuclear or renewable energy, there's no particular reason to make the sacrifice in efficiency required by this extra step. Either can be used to generate electricity to charge batteries; electric vehicles can be conveniently refueled at customers' homes or places of work.

Thanks for the podcast John. and for sharing other encouraging news about developments in the UK leveraging green ammonia! GenCell Energy absolutely agrees with your contention that ammonia can be the silver bullet that resolves the barriers to hydrogen transport and storage, allowing hydrogen to be cost-effective and go mainstream.  GenCell's technology will allow adaptation of existing fuel stations to extract hydrogen from liquid ammonia in order to power buses that run on fuel cells - exponentially reducing the cost of hydrogen. With lower costs, shorter fueling times and less pressure on electricity grids, hydrogen FCEVs with the help of ammonia can become an increasingly attractive alternative to heavy battery-powered EVs that require long duration charging, problematic battery disposal and replacement and that create issues for grid stability in many locations. 

As you wrote in your earlier post on the topic, "If you can make green Hydrogen  and green electricity you can make green ammonia. You just need a lot of green energy! I do think the focus now could and should be on de-carbonising the world’s existing ammonia demand… this would then provide a sound footing for Ammonia to potentially be used as a green fuel!" 

As hydrogen is being selected to power more and more varied applications, the demand for hydrogen is rising. And as the demand for hydrogen increases, so does the justification for green hydrogen. It makes a lot of sense to leverage surplus renewable energy that would otherwise be wasted to produce green ammonia that is far more easily and economically stored and transported than any other hydrogen carrier. This emission-free green liquid ammonia can be consumed as fertilizer or used in pesticides, can be processed in a variety of industrial applications such as refrigeration or water purification, or can be shipped to virtually any destination and be stored and stand ready to be cracked at any time to provide an efficient, dense and rich source of hydrogen to generate electricity via fuel cells. New technologies for producing green ammonia will allow the world to rely on hydrogen as the optimal path to decarbonization, and in so doing we will be better placed to combat climate change.