> For example, you can't make ammonia from electricity but you can from heat generated by either fossil fuels or nuclear.

This is wrong for two reasons.

One: you can make heat with electricity from renewables sources, if that were necessary.

Two: you don't need heat because you can make ammonia with green hydrogen from electrolysis then follow the standard Haber-Bosch process. The normal fossil route does this too but gets the hydrogen by splitting fossil gas and vents the waste CO2.