ReCiPe 2016 (H) vs (H) no LT: Handling long-term emissions in Landfills

Question

Hi OpenLCA community!

I am currently performing an LCA study focused on waste management (specifically sanitary landfills) using ecoinvent datasets. I have encountered a significant sensitivity issue regarding the temporal horizon of emissions, and I would like to ask for advice on the current "best practice".

 When analyzing the results using ReCiPe 2016 Endpoint (H) of "treatment of municipal solid waste, sanitary landfill | municipal solid waste | Cutoff, U", I observed that the flow "Zinc, ion" categorized as "emission to water, ground-, long-term" appears as a relevant hotspot, dominating the Human Health category.

However, when I switch the method to ReCiPe 2016 Endpoint (H) no LT, this specific contribution disappears completely, drastically changing the overall impact profile.

I understand that the "Long-Term" (LT) sub-compartment in ecoinvent refers to emissions occurring after 100 years, and that the "no LT" version of ReCiPe assigns a characterization factor of zero to these flows to cut off the assessment at the 100-year mark.

For standard sustainability reporting, is there a consensus on which approach is more appropriate? Is it recommended to include these long-term emissions or is it standard practice to exclude them (H, no LT) to focus on the manageable operational timeframe?

I would appreciate any references to guidelines that address this exclusion.

Thanks in advance for your help.

Fernando

Answer 1

I cite from ecoinvent:

So far no consensus has been reached among LCA experts if and how long-term emissions should be taken into account. Until the debate is settled, ecoinvent allows users to decide themselves whether to include it. Therefore, long-term emissions are reported separately via two subcompartments explicitly labeled as “long-term”, namely “air, low population density, long-term” and “water, ground-, long-term”. Those exchanges are exclusively present in waste treatment datasets, where it is assumed that the active landfill maintenance ends after 100 years. Since long term emissions are in the environment 100 years less than short term emissions, their CF should be lower. However, most LCIA methods do not provide a distinction of time horizons. Thus, two options are possible: 

Attribute the same CF to both short term and long-term emissions, leading to an over-estimation of the impacts. Attribute no CF to the long-term emission, leading to an under-estimation of the impacts. 

ecoinvent provides the results for both options, allowing you to test the sensitivity of your conclusions. The results without long-term emissions are available in methods explicitly labeled as “no-LT”. 

In EPDs usually no long-term emissions are included. Also in LCA studies I see more often to not include them. But that's why a sensitivity analysis is needed. And as in your case, there can be large differences, which should then be discussed in the LCA report and checked if these are plausible ones. The end-of-life data sets are also just generic data sets which cannot cover each individual LCA model.