I am modelling an industrial process and now I get negative values for certain steps... I am using Ecoinvent v3.9 and OpenLCA v1.11.0. For the LCIA I used ecoinvent-CML v4.8 2016. When I just run the calculation everything is fine and all numbers are positive, but if I want to know the contribution of each substep, I get some negative values. For example: for the CO2-eq: step 12: 74.6325 and for step 13: 73:6858. So if I want to know the share of step 13, logically I do Step 13 - Step 12 = 73:6858 - 74.6325 = -0.9467. This can't be right since these are consecutive steps in an industrial process and chemicals like ethyl acetate and liquid nitrogen are used but not recovered.
Is this even possible to have negative values for this?
Thanks in advance for your answer.
These are the results I get when following the advice of Sjamil. However, when calculating with the "Project" option, I get the exact same numbers. This is a problem because into step 10 go Step 6 and Step 9 (screenshots also added below) and as you can see, step 10 - step 6 - step 9 = less than zero. (In the original question I spoke of step 12 and step 13 and I also still have the same problem there.
Screenshots of step 10:
Screenshots of step 9:
Screenshots of step 6: