Dear Ecoinvent forum,
where can I found a reference / document explaining the main differences between the life cycle inventory data of PlasticEurope and Ecoinvent ? For instance, the GWP of EPS is roughly double CO2eq/kg resin in Ecoinvent 3.5 (the unit model "allocation, recycled content / cut-off....cradle to gate production, RER), compared to the CO2eq/kg (Ecoprofile of Expandable Polystyrene (EPS) PlasticsEurope February 2015). Where dose this GWP difference come from ?
Thank You
Stefano
Hi Stefano,
Thanks for your question. The relevant PlasticsEurope report is either mentioned in the documentation or in the corresponding version 2 report. You can access the version 2 reports in ecoQuery (ecoinvent online). For EPS, the ecoinvent dataset ‘polystyrene production, expandable, RER’ is based on the 2005 Eco-Profile from Boustead (you can still find the paper e.g. here). The published GWP is this report is 3.3 kg CO2 eq, whereas the ecoinvent GWP in the cut-off system model is within few percent. Small deviations as these can be explained with the different background data and – if applicable – different allocation strategies.
I would like to remind you not to publish scores in the forum, since these scores are only visible for users with a license. If you need to mention scores to clarify your question, please send us an email to support@ecoinvent.org.
I hope this answers your question.
Kind Regards,
Daria Dellenbach, Junior Data Analyst, ecoinvent association
I guess the large differences (yes, they are large, e.g. for the PET granulate production) are stemming from the different background system. For example, the granulate production has an input of electricity with the average European grid mix as a provider. In contrast, the original eco profile used the actual grid mixes of the producers which probably have lower footprints.
Dear Bernhard,
In the case of the process mentioned in this thread 'polystyrene production, expandable, RER', as Daria explained, the differences simply stem from the comparison of an old vs a new ecoProfile. In fact, the values in ecoinvent are very close to the ones reported in the old ecoProfile. The dataset in ecoinvent is mostly an aggregated dataset apart for the waste by-products, those explain the small variation with the old report.
In the case of PET granulate, the data comes directly from PlasticsEurope (introduced in version 3.6 of the database). In this case, the reasons for the differences is indeed the background data. If I remember correctly the main differences do not stem from the electricity mix but from the material inputs supply chain.
In general when comparing ecoinvent to ecoProfiles, the following shall be kept in mind:
• The data in ecoinvent is included at the unit process level and therefore linked to ecoinvent as a background.
• The used version of a background database can also cause differences in scores.
• Not all the data from PlasticsEurope is included in ecoinvent, which means that we do not have the full supply chain from PlasticsEurope. We are working with PlasticsEurope to improve and update data.
• the choice of allocation/sub-division applied might not be the same in ecoinvent as the ones made in the eco-profiles.
Best regards,
Lucia