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State warns of possible rolling blackouts amid scorching heat wave

The heat wave is stretching into the seventh day and relief is not expected anytime soon which means the demand for energy is straining the grid. The California Independent System Operator has issued a Flex Alert asking residents to conserve energy during peak use but as KPBS reporter Alexander Nguyen shows us it is also tapping other sources for energy.

The operator of the state's power grid warned residents Tuesday to prepare for possible rolling blackouts, as a drawn-out heat wave reaches its peak and drives electricity demand to an anticipated record level.

The California Independent System Operator extended a Flex Alert until Tuesday, urging residents to take all possible measures to conserve electricity during the peak hours of 4-9 p.m. for the seventh consecutive day.

On Tuesday morning, Cal-ISO declared an Energy Emergency Alert 1 for the same hours, warning utilities that all electricity resources are expected to be fully committed and some shortages are possible. By early afternoon, Cal- ISO moved to Energy Emergency Alert 2, requesting all available emergency supplies to be made available to meet the demand.

Cal-ISO officials declared an Energy Emergency Alert 3 — meaning rolling blackouts are imminent, and calling for maximum conservation efforts by all residents — Tuesday evening.

"As the state faces the hottest day in this prolonged, record- breaking heat wave, grid conditions are expected to worsen," according to the power-grid manager. "If needed, ISO could order utilities to begin rotating power outages to maintain stability of the electric grid. If that occurs, consumers should expect communications — either phone, text or email — from their utilities notifying them of outage areas and likely durations."

If energy reserves are exhausted, the ISO would instruct utilities in its service area to manage rolling blackouts. Utilities make the determination of how best to spread and rotate the outages across their service territory, with the goal of keeping them as short as possible.

"Outages are a significant inconvenience to those affected, but it's preferable to manage emergencies in a controlled manner rather than let it cause a wider spread, longer lasting disruption," according to Cal-ISO. "Power interruptions are kept as brief as possible and utilities rotate them through their customer base so that no one area has prolonged outages. Utilities make the determination of how best to spread and rotate the outages across their customer base, with the goal of limiting their duration as much as possible."

Cal-ISO officials said calls for conservation have paid off so far during the heat wave, with no power interruptions occurring. But they are predicting record demand on Tuesday.

Current forecasts predict peak demand at 52,079 megawatts on Tuesday, which would break the record of 50,270 MW in 2006, according to the ISO. Wednesday's load is forecast at 49,868 MW. The ISO reported Monday that it was projecting supply deficiencies of 400 to 3,400 MW between 5 and 9 p.m. Tuesday.

Consumer and commercial demand response, including Flex Alerts, has been helping to extend tight resources over the past week, with a load reduction of around 1,000 MW for each of the past several days.

During the Flex Alerts, residents are urged to take the following power-saving steps:

— setting thermostats to 78 degrees or higher;

— avoiding use of major appliances;

— turning off unnecessary lights; and

— avoid charging electric vehicles.

Residents are also advised to pre-cool their homes as much as possible and close blinds and drapes to keep interiors cool.

Southern California has seen temperatures soar above 100 degrees every day since last Wednesday, with little relief in sight until at least Friday.

Overnight lows are not offering much relief either, staying in the 70s and even in the low 80s in some of the hotter areas.

High temperatures continued Monday across much of San Diego County. The high reached 86 in downtown San Diego, 90 in Chula Vista and a scorching 109 in Borrego Springs.

The National Weather Service extended the excessive heat warning that has been in effect all weekend, which is now set to expire at 8 p.m. Friday.

"Strong high pressure to the north will continue the heat wave through Thursday for inland areas, with the heat continuing through Friday for the coast and valleys," according to the NWS. "For next weekend, a weakening tropical system will bring increasing moisture, breezy conditions, and a chance of more widespread showers and isolated thunderstorms. Showers and higher humidity will linger through early next week."

Health officials advise residents to stay indoors with air conditioning whenever possible, drink plenty of fluids and avoid hiking or other strenuous activity in extreme heat.

Children and pets should never be left in unattended vehicles for even one minute.

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