It was obvious why there were rolling blackouts during the heat wave we had in mid-August. There was a huge high pressure dome over the western states and demand in the other states took away from the normal amounts of power that California imports from other states. Much of the imported power comes from Palo Verde Nuclear generating plant in Arizona and from the Pacific DC Intertie near the Dalles in Oregon. Also the Intermountain DC Intertie in Utah.
Another thought that should be considered. There were plans to connect the Eastern and Western grids of the US at a point at Tres Amigas (see note below). This could have saved the consumers money by distributing the loads. But the fossil fuel industry got the FERC feds to put it on hold because it would reduce the amount of coal being used. So the two halves remain disconnected.
Note:
A quote from here
<< On October 13, 2009, the Tres Amigas SuperStation was announced to connect the Eastern, Western and Texas Interconnections via three 5 GW superconductor links.[3] As of 2017, the project was reduced in scope and only related infrastructure was constructed for nearby wind projects connecting to the Western Interconnection.[4]
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