Hi there,
When I model 1 kg of diammonium phosphate production (phosphate fertiliser, as P2O5) using ReCiPe 2016 Midpoint (H), I get a negative value for kg CO2 eq scores in the global warming category. I see that nitrogen fertiliser is modelled as a negative input in this process, however I am unable to explain specifically why this is the case?
Hi Ciara,
Thanks for your question. The consequential model uses different basic assumptions to assess the consequences of a change in an existing system. It can be used for perspective studies and prediction of future changes. You can read more about those assumptions and find an explanatory video here. One of these assumptions is, that by products of undefined unit processes are moved to the input side with a negative sign, this models a reduction in the demand from the market. This is the reason why nitrogen fertiliser has a negative sign in the dataset you mentioned. Please make sure, this is the right system model for your work.
With the launch of ecoinvent 3.7.1, the fertiliser modelling was re-evaluated, you can find a more detailed description in the report of changes.
And I would like to remind you that we ask our users to not publish LCIA scores in the forum, since those are only accessible for users with a license.
I hope this answers your question.
Kind Regards,
Daria Dellenbach, Junior Data Analyst, ecoinvent Association