Emission limits - Impact on solving time and forcing intervals

Q&A
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1

Dear All,

two quick questions:

  1. since setting an emission limit is an important constraint for reducing the solution space of all viable solutions, can increasing the emission limit therefore have a significant impact on solving time?
    and 2) (related to that) can therefore setting an emission constraint to force a solution to be within an interval (i.e. x <= emission_limit <= y) help to reduce solving time? Has anyone had experiences with setting intervals for constraints?

Thx in advance and all the best,

Moritz

2

Hi @moritz_reuter,

Thanks for bringing up the topic. Actually, it’s rather hard to give general answers to these kind of questions. If you find or conduct a representative study, please share the results.

From my experience the general tendency is that additional constraints will prolong the solving time. However, if constraints are irrelevant, the impact can be negligible. So, your option 2 will probably not reduce the time to solve the problem but do the opposite. Option 1, on the other hand, might have no effect, e.g. if setting a high upper emission limit while global costs of emissions are considered already.

Cheers,
Patrik

3

Hey Patrick,

I just wanted to close this thread by sharing that I was able to confirm your intution and that I can only recommend that most do not use hard emission_limits UNLESS you are attempting to model a cost-optimal “0-Emission” System and have provided sufficient technologies with zero emissions :slight_smile:

Hope this came in handy for others!