California ISO reduces estimate of summer power shortfall

Compared to a previous analysis, the California Independent System Operator has cut is power supply deficit forecast for this summer. The ISO said it identified additional resources and will cut its required reserves to help meet demand and reduce the number of blackouts. The measure will cost $800,000/month in fines. Nonetheless, the grid operator still expects rotating outages throughout the summer.


By Ann de Rouffignac
OGJ Online

HOUSTON, Mar. 27�Compared to a previous analysis, the California Independent System Operator has cut is power supply deficit forecast for this summer.

But the outlook is still riddled with blackouts. Instead of being short 6,815 Mw in June as the previous forecast suggested, now the ISO says the deficiency will be 5,943 Mw given a peak load of 47,703 Mw. The picture continues to brighten somewhat as the summer goes on with the difference between resources and peak load narrowing especially in July and August.

For July, the ISO identified an additional 3,241 Mw of power to reduce outages expected at peak to 3,740 Mw, compared to a previously forecast deficiency of 4,685 Mw. The ISO�s forecast assumes the utilities' financial problems will be resolved. If not, the situation will be much worse, said Ziad Alaywan, ISO�s managing director of engineering.

ISO staffers reviewed the amount of power available from the qualifying facilities or independent renewable and cogeneration facilities and came up with an additional 1,000 Mw, compared to a previous forecast.

�The majority of the change in June�s forecast is in the QFs,� said Alaywan. He said the previous forecast assumed 4,800 Mw would be available from the QFs, but that has been raised to 5,814 Mw.

The ISO further whittled down its supply deficit for each month in the new forecast by identifying �mitigation measures.� These include interruptible load, demand relief programs, and reducing the amount of power kept in reserve.

For June, these measures will bring the deficit down to 3,647 Mw from 5,943 Mw. In the previous forecast the ISO said it couldn�t count on any interruptible load from the utilities since the programs were currently under review by the Public Utilities Commission.

Alaywan said the California PUC claims 2,000 Mw of interruptible load will be available by summer. But the utilities themselves have no idea how much interruptible load to count on, he said. In the updated forecast, the ISO has included 400 Mw of interruptible customers but that's just a "guess," Alaywan said.

The ISO also has instituted its own demand relief programs and expects to have 596 Mw of confirmed interruptible load.

Last summer, the ISO could count on 1,000-2,700 Mw of interruptible load, helping tide the ISO over many tight spots.

Reducing reserves
But the biggest addition to the summer forecast is 1,300 Mw added by doing without some reserves during peak periods. At a peak of 47,703 Mw, 7% or 2,600 Mw, are required to be kept as operating reserves.

Half of that must be in spinning reserves or unused capacity connected to the grid that can instantly respond to system requirements. The other half must be nonspinning reserves which must be on line and available within 10 minutes.

�In order to convert the 1,300 Mw of nonspinning reserves to energy we have to pay a fine to the WSCC [Western Systems Coordinating Council],� said Alaywan. The maximum fine is $800,000/month and the ISO plans to have to pay that every month during the summer, he said.

The state can import up to 19,800 Mw of power from the Northwest and the Southwest. Municipally owned utilities within the ISO�s control area have first call on 40% of transmission capacity for imports. The 9,800 Mw balance is available to the ISO. But availability of power from out of state is limited.

The ISO is counting on receiving only 5,357 Mw of imports, said Alaywan. That includes 1,857 Mw of power from out-of-state generation controlled by California's investor-owed utilities.

Even though new summer forecast is more optimistic, Alaywan said it is predicated on using all available in-state hydroelectric power during the peak. Despite drought conditions throughout the West, the ISO forecast assumes 10,000 Mw of hydroelectric power will be available. Under ideal conditions the maximum output is 11,000 Mw.

At times other than peak, the full 10,000 Mw of hydro might not be available. All of the 10,000 Mw can only be expected to run for about 2 hr at a time, he said.

�You can�t have all the hydro running all the time. There may be a limitation of hydro during specific times of the day,� he said.

At times other than peak load, California could have trouble meeting load requirements and might still have to drop load or impose blackouts because the ISO must carefully weigh when to run the hydroelectric resources.

�We have to consider when it�s worse to drop load. Is it better to be without electricity in the morning when everyone is at work or in the late afternoon when everyone is coming home,� he said.

Contact Annd@OGJonline.com

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