While Cal-ISO — the state body that determines how much power generation municipalities require — seemed amenable to shutting down the plant's Unit 3 smokestack when the highly touted transbay power cable comes online early next year, it was not willing to pull the plug on Mirant outright. Citing a potential city shortage of 25 Megawatts, Cal-ISO was not yet ready to give assent to close Units 4, 5, and 6. The body pledged to complete an analysis within two months regarding whether it is viable to shutter those units.
The city has long held that decreased overall power demand would allow San Francisco to meet its power quotas without adding any additional generation. At the August press conference announcing the city's settlement with Mirant, Public Utilities Commission head Ed Harrington described that so-called 25 MW shortage as “overly cautious”: That figure assumed “two major
power transmission cables went down on the peak hour of the peak day
and no one ever made any change in their behavior when it happened.”