Why is 2 to 3 times more capacity offline this year compared with previous years? I don't know. It appears the "supply" shortage is not due to increased demand, or even the lack of new power plant capacity; but due to the shutdown of existing capacity by generation companies at a higher rate than normal.
I think more capacity is offline than previous years because of a large number of factors. Some of the most important are: 1) The ISO has designated more "no touch" days than in previous years. This makes it harder for plant operators to schedule their maintenance effectively. Less effective normal maintenance means more emergency and unplanned maintenance. 2) The PG&E bankrupcy combined with other utilities being unable (or unwilling) to pay their bills has resulted in generators not getting paid. Generators are hard pressed to keep their plants running when they aren't being paid and don't know if they will ever be paid. 3) The increased prices earlier in the year prompted utilities to produce more of their own power and to buy as little as possible from outside sources. This means that more plants have used up their air pollution allotments for the year. It also means that more maintenance is needed now than would otherwise be required at this time of the year. Personally, I'm fairly certain that most of the blame for our current crisis rests with the courts who compelled the utilities to buy power regardless of the price. There is absolutely no rational defense for this ruling that I can imagine, and with no bargaining power, the utilities were raped by the generators. David Schwartz