Resolve issues with the REGION index, so that multi-region models with trade can be developed

[willu47]

At present, no models use the REGION index for its intended purpose of creating multi-region models. Instead, regions are implemented through naming conventions.

I have heard various reasons for not using regions:

• using the REGION index results in poorer model performance
• implementing trade is difficult due to missing parameters for capacity Trade between REGIONS lacks parameters #62

Are there any other reasons for not using the REGION index? Can these issues be overcome so that we can start using the REGION index?

[HauHe]

Hi,
thanks for opening this issue and discussion @willu47. With Capacity you already cover the main issue, but to my understanding trade lacks any kind or parameter options that we have with technologies. Hence, using the trade options requires to create more technologies if one wants to parameterise the trade.

[willu47]

@HauHe - the current implementation of the TradeRoute parameter seems to set up links between FUELs of the same name in different regions. Could this allow import/export technologies to be defined using special import/export fuels in different regions?

[HauHe]

Yes, I that should work. But I think one then would have two times more technologies per link than one would have without using the sets REGION. With two modes of operation one would have one technology per region per link. With one mode of operation two technologies per region per link.
When I thought about if I should switch to using the set REGION that was what kept from doing so.
But perhaps there are advantages of using the regions, that I just didn't see, and I guess with the latest improvements to avoid lines of zeros a few more technologies might make such a big difference in computation anymore.

[TomAlfstad]

I think it would be good to pursue this issue. The concerns/lack of use with the trade implementation seem to be related to limitations/problems with how it is implemented rather than an inherent problem with using regions. Duplication/performance issues should be manageable with preprocessing of data files and it would lead to a more intuitive use of regions and trade in Osemosys models.

[trevorb1]

If useful, here is a paper that addresses some issues with the region index and includes a power transmission module in OSeMOSYS.

Title: Assessing the relative impacts of maximum investment rate and temporal detail in capacity expansion models applied to power systems
DOI: https://doi.org/10.1016/j.energy.2024.130231