System expansion

Question

I'm currently working on a project that involves comparing processes related to animal waste management technologies. I'm using system expansion to "credit" systems that produce co-products compared to a baseline scenario (i.e.electricity production from CHP conversion of biogas from anaerobic digestion or N fertilizer from nutrient recovery). I've talked to several LCA users and have gotten several different answers on how to properly model these systems. If I have a system that generates more product than the baseline system can I "credit" that system for the entire amount generated or only "credit" up to the amount originally produced in the baseline scenario? If the latter is true how can one "credit" the additional product that is generated?

Thank you!

Shannon

Answer 1

This question goes a bit beyond openLCA and is more LCA methodology; if one of your systems produces more byproduct than the baseline scenario, I think it is up to you. You only need to ensure that the benefit provided by all compared products (as quantified) is identical, but maybe, since there is always some decision in defining processes used for system expansion, you are better off crediting only the "surplus byproduct" (if I understand the question correctly).

Best wishes,

Andreas