Different results in cost calculation between System and Unit Processes

Question

Hello,

I created the same exact process, using APOS system model, with system and unit processes. When i calculate with GWP100, i get the same results, but when i perform a cost calculation, the results are fairly different. With system processes, i get a net cost of -0,02259 euros. With unit processes, i get a net cost of -0,15560 euros. Im using the default costs/revenues of Ecoinvent.

 The system processes results are represented in the dark mode figures and the unit processes in the light mode.

Is this expected?

Also, is it "normal" to get a negative net cost value and a positive added value?

Thank you for the help!

Answer 1

Hi, interesting question, I would say that the cost part in the ecoinvent datasets gets less attention from ecoinvent than the entries relevant for the environmental assessment - I would think the unit process result is more trustworthy, but would be interested if you can post more details. Thank you!

Andreas

Comments

Hello, thank you for taking the time to answer and help.
I'll add some examples to the post. I'm moddeling a waste treatment process and would like to access the potential economic benefit of avoided products.