What to consider when using a process created by ecoinvent vs when I want to create it myself

Question

Hello,

I am comparing hydrogen technologies in OpenLCA, including  how does different production methods of hydrogen affect on the study. For the production of grey hydrogen I used the proess in Ecoinvent 3.8 "hydrogen cracking,APME | hydrogen, liquid | APOS, S-RER" and for the green hydrogen production, since there is no water electrolysis process, I created a process from data published in the paper "Using harmonised life-cycle indicators to explore the role of hydrogen in the environmental performance of fuel cell electric vehicle"

However, in the LCIA I obtain that the technology using green hydrogen has a biggest environmental impact that when using grey hydrogen, which is of course wrong. I wonder if there is any special fact I need to take into account when creating a production process of my own, which will need to be compared with an already created one by Ecoinvent. 

Thank you!

Anna

Answer 1

Hello Anna,

This does in fact sound wrong. Whats important when you create your own process, is to ensure that you have entered all the data correctly. Especially make sure that all units and suppliers correspond to the article, and that the reference output corresponds to the output from the article.

If you are certain of this, then there are some further steps you can take.

1) Investigate the contribution tree from both processes, and evaluate directly if some of the processes should be more/less impactful.

2) Consult other analyses made, and see if their hotspot analyses match yours

3) Read the documentation for the processes you'd expect to be most impactful. Are they missing some steps? Do you need to add elementary flows manually?

I hope this helps, good luck in your search.

Answer 2

you propbably want SMR, not hydrogen cracking FYI

check your power source and choose one that fits your country. If the input grid is fossil dominated, it is likely that the electrolysis will have higher co2 eq.

Which impact category are you looking at?