I would like to ask a detail about the urea production, as N [RER] process in ecoinvent.
The description claims that CO2-consumption during the production of urea was not included, because it arises as a by-product during the production of ammonia. However, looking at the upstream process of ammonia production hereby the full amount of CO2 is emitted during the ammonia production, not excluding the CO2 which is going to be used for the final urea production (1,46kg CO2/ 1 kg ammonia, liquid).
Does this assumption not lead to an overestimation of the CO2 emissions of urea?
Thank you very much for your consideration.