Trade process modeling

[myhan]

Excuse me,

Scenario 1: A 10GW bidirectional transmission link exists between Region A and Region B.
Scenario 2: A 10GW unidirectional transmission link exists between Region A and Region B.

When defining capacity stock, should it be defined in both Region A and Region B, or only in one region? Beyond specifying bidirectional or unidirectional transmission, are there other differences to note during these two definition processes?
I would be most grateful if you could reply.

[Antti-L]

By "capacity stock" I assume you mean the the existing capacity of transmission links.
I'd say it is all up to the modeller, whether to define that in both Region A and Region B, or only in one region. By default, the capacity limits the flow in both directions, and therefore it would not make any difference having the capacity on one side only or on both sides. But recall also that if you model transmission efficiencies with IRE_FLO, that would also affect the capacity requirement on each side, and therefore I think using IRE_FLOSUM instead is usually a better alternative for modeling transmission losses.

However, if you would like to model capacity-related costs as well, and allocate those costs to both regions, you could do that by defining the capacity and capacity costs on both sides. Doing so would not change the optimal solution, but only the cost reporting.

For new transmission line capacities, the situation becomes a bit more delicate, because then, if modeling the new capacity investments on both sides, you need to make sure the costs will not be "double-counted". I have seen some modelers choosing to put half of the investment costs on each side.  But here again, it is up to the modeler.