The Northwest spent billions building transmission to connect to the rest of the West. This enables surplus electricity sales that offset the regional cost of electricity and allows purchases when the regional need exceeds the capacity of regional generators. Relying on electricity purchases from outside the region defers the need to build new generators, which reduces the cost of using electricity. However, maintaining reliable electricity requires both transmission to the Northwest and available generators outside the region. 

Our baseline setup limits the amount of imports from the external market. After accounting for imports from power plants that are located outside the region but have contracts or obligations to deliver electricity to the region, the analysis limits regional imports to no more than 2,500 megawatts in the winter and 1,250 megawatts in the summer. Those limits are well below the ability of the region to import electricity on our transmission system. Because the Council has less information on the supply and demand for electricity outside the region, the Council uses these limits to represent uncertainty about the availability of electricity during times when the region is short of generations and fuel.

For this scenario the Council relaxed these limits to allow the region to import up to the capability of the transmission system. While this reduced the adequacy-needs input into our resource analysis, the results from our models had minimal changes to the resource additions examined. While there were some minor changes to the pace at which renewable generators are built within the region, the overall results did not indicate removing these limitations would change the resource strategy.