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Dear Members,
I trust this message finds you well. Currently, I am delving into the behavior of specific technologies and noticed instances of activity without corresponding installed capacity. Based on my experience with other modeling tools, I typically expect a clear mapping that distinguishes technologies where investment decisions are relevant. Within the framework of TIMES, I am interested in understanding whether similar definitions exist that differentiate technologies based on their involvement in investment decisions. It appears that certain technologies demonstrate activity even in the absence of installed capacity, and I am keen to comprehend the underlying principles or considerations driving this situation. Notably, I have observed the absence of defined investment costs. Could this be the reason, and what other factors might contribute to such a situation?
I appreciate your time and assistance in shedding light on this matter.
Best regards,
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> Based on my experience with other modeling tools, I typically expect a clear mapping that distinguishes technologies where investment decisions are relevant. Within the framework of TIMES, I am interested in understanding whether similar definitions exist that differentiate technologies based on their involvement in investment decisions.
This is an interesting question, but having read the documentation you should know that there are no variables in TIMES directly representing investment decisions. TIMES has only the VAR_NCAP decision variables for new capacities, which may or may not involve investment costs. The investment costs are defined by the user only, and so whether the decision to install new capacity involves an investment is completely up to the user.
As for the capacity variables, they are indeed not always included for processes, but only under certain conditions. As far as I know, these conditions have never been meticulously discussed and designed, and therefore questioning them can be well justified. But thus far, over many years, I have not heard of any notable issues raised about those conditions, which are the following: Capacity variables are included iff any of the following conditions hold:
● The process has some existing capacities defined (NCAP_PASTI/PRC_RESID);
● The process has some capacity bounds defined (NCAP_BND/CAP_BND);
● The process has investment costs, taxes or subsidies defined;
● The process has fixed costs, taxes or subsidies defined;
● The process has decommissioning or safe storage costs before decommissioning defined;
● The process has fixed availability/utilization factors defined;
● The process capacity variables (VAR_NCAP/VAR_CAP) are involved in some user constraints.
As you can see, the conditions are pretty simple, and the purpose of them is to avoid including any such capacity variables in the model that might just take arbitrary values without otherwise affecting the model solution (objective function). Including such would be bad for many solvers, and would also make the model a lot bigger without any meaningful purpose.
If you have encountered or you are otherwise able to see any shortcomings with these conditions, please present your suggestions for improving them, describing the "clear mapping that distinguishes technologies where investment decisions are relevant" you would expect to be applied. The option of always including capacity variables (which was the default in the very initial TIMES versions) is also available, but I think it cannot really be recommended to be used.
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Dear Antti,
Thank you for your comprehensive response! Your insights have been helpful in understanding the intricacies of the model and addressing the main issue I was facing. I appreciate your time and expertise. Regarding the improving task, I suppose your the discussion provides a valuable starting point for further exploration and I'll return to that later.
Thanks again for your assistance!