If we stop using fossil fuels to make chemicals and materials, we'll need vast quantities of electrolytic hydrogen. Ammonia production alone was about 175 million tonnes in 2016, requiring 31 million tonnes of hydrogen. At 50 kWh per kg of hydrogen, that would be roughly 177 GW of electrolyzer capacity working at a 100% duty cycle. Using hydrogen in place of coal for reducing iron ore would consume even more hydrogen.

https://en.wikipedia.org/wiki/Ammonia_production

Japan is interested in it as fuel, despite the well known drawbacks, because Japan has such limited domestic energy resources.