Replying to a number of previous comments on energy balances. The reaction N2 + 3 H2 -> 2 NH3 is exothermic, giving off energy [1]. N2 is abundant and free (80

Replying to a number of previous comments on energy balances. The reaction N2 + 3 H2 -> 2 NH3 is exothermic, giving off energy [1]. N2 is abundant and free (80% of the atmosphere), but H2 is not. The most common way [2] of producing H2 is from hydrocarbons (oil/gas products). In principle H2 can be produced from something else (e.g. water, through electrolysis), but that is very energy intensive [1], making the overall reaction N2 + 3 H2O -> 2 NH3 + 3/2 O2 a net energy consumer. Point being, yes, it might be possible to save energy compared to the Haber-Bosch process, but the net production of ammonia from free/abundant materials will not ever be "for free" energy-wise. [1] https://en.wikipedia.org/wiki/Standard_enthalpy_of_formation https://en.wikipedia.org/wiki/Standard_enthalpy_of_formation [2] https://en.wikipedia.org/wiki/Hydrogen_production https://en.wikipedia.org/wiki/Hydrogen_production