comparison between car and train

Question

Hi,

I am calculating a comparison between use of car and train. In my understanding there must be difference in results If I use 50 or 1000 km as amount for the flow. But the results differ only by factor 20 - how can this be? As by using the car 50 km but 20times, there should be more emissions, caused of starting?

KR

Lynn

Answer 1

This is an expected result as everything is scaled linearly in an LCA model (see e.g. Heijungs and Suh: The Computational Structure of Life Cycle Assessment).

There are tricks that you can apply with parameters (e.g. co2 = distance * emission_factor + number_of_starts * startup_factor + ...) or splitting the process (e.g. you could create a process with emissions for a 50 km chunk and than in the input you define how many chunks per output you need). But this depends on your model and is still scaled linearly in the end.

Comments

Thank you very much. I will try to use parameters, because I am interesting for the results. Is there any initiative to renew this aspect of lca? Because this occurs in different cases - or?
KR
Lynn