SACRAMENTO, Calif. — With a heat wave far from over, state energy officials anticipate more Flex Alerts through the week ahead.
Reducing energy use during a Flex Alert is voluntary, but experts say everyone doing their part is a proven way of avoiding power outages.
Let’s start with your home and the appliances you use on a daily basis. Powering a dishwasher for one hour uses more than 300 watts, according to U.S. Department of Energy. A clothes dryer uses close to 3,000 watts and a pool pump— around 1,000 watts.
All these electricity-powered devices - from the biggest ones down to your phone charger - make up your home’s energy use, or “demand.”
Add up all the homes on the grid, plus businesses and other energy-users, and we see demand is highest in the late afternoon – as the temperatures are hottest and air conditioners are blasting - and through a couple of hours after sunset, as people are lighting their homes and doing other tasks requiring electricity.
Normally, there’s a comfortable gap between energy demand and energy supply, but where the power grid is stressed, that gap narrows.
Dan Kammen, a UC Berkeley Professor and sustainability expert, said Flex Alerts – voluntarily reducing your energy use during peak grid-demand hours – are a critical way to help avoid brownouts and other power outages.
“You can plan in advance. You can pre-cool…And then, of course, during the actual Flex Alert itself, not running critical loads, washing machines…high power devices, turning off hot tubs…scheduling charging of electric vehicles outside of those critical windows - all make a very big difference,” he said. “In the past, Flex Alerts have been really quite significant. We've seen up to 10% or more reduction in peak demand if people and companies, businesses, really get engaged, and that can save all of us quite dramatically over these coming days.”
But who decides when we need a Flex Alert?
First, let’s talk about the broader power grid. The lower 48 states are divided into three interconnections: Eastern, Western and Electric Reliability Council of Texas. Texas’ isolated power grid was as problem in Feb. 2021, when a winter storm knocked out power to much of the state. Because they’re not interconnected to other grids—they couldn’t pull from other states’ supplies.
The Eastern and Western interconnections are made up of “balancing authorities,” which basically act as control towers for the utilities they oversee – and talk with other control towers. As the U.S. Energy Information Administration puts it, “a balancing authority ensures, in real time, that power system demand and supply are finely balanced. This balance is needed to maintain the safe and reliable operation of the power system. If demand and supply fall out of balance, local or even wide-area blackouts can result.”
The biggest balancing authority in this state is the California Independent System Operator – or Cal ISO, which oversees 80% of the state’s electricity.
They’re the ones who declare Flex Alerts, and other, smaller balancing authorities typically follow suit.
On Sunday, Cal ISO’s President and CEO Elliot Mainzer said more energy conservation will be needed in coming days.
“Peak demand is currently forecast to increase to 48,967 megawatts on Monday and 50,099 megawatts on Tuesday, which is close to the all-time record load demand for the system that was set in 2006. Demand is also forecast to be high on Wednesday at 49,268 megawatts and persist at very high levels through the end of next week,” he said. “We know this has been a long haul and it's going to get more difficult, but your efforts have been working and your sustained efforts to flex your demand between 4 to 9 p.m. will help us maintain the overall reliability of the grid.”
On Monday, the forecasted peak energy demand for Tuesday rose to what would be a 25-year record: 51,145 MW.
Due to the heat wave affecting much of the Western U.S., California can’t easily pull from neighbors when the energy grid is strained.
The last time California saw high energy demand like what’s forecasted for Tuesday was in mid-August 2020, when the state saw rolling power outages. It was during an extreme heat wave the affected many of the western states.
Peak demand back in 2020 was 47,121 megawatts (MW).
Since then, the state has added about 4,000 MW to the grid through clean energy and about 2,000 MW more in emergency generators and other reserves.
However, Gov. Newsom notes, the prolonged drought has reduced the state’s ability to produce hydroelectric power, plus the length of this particular heat wave is putting extra strain on the grid. That, again, is why following Flex Alerts is so important to avoiding power outages.
Cal ISO also tracks the date and time during which energy demand was highest in any given year.
Over the past 25 years, that yearly peak has landed anywhere from June to September—and all between the hours of 2:30 and 5:50 p.m. That peak has been as low as 41,419 MW (in 2001) and as high as the 25-year record of 50,270 MW in 2006, with 2017 trailing close behind at 50,116 MW.
That’s why Tuesday’s forecasted peak demand of 51,145 MW has state energy officials urging people to follow the Flex Alerts. If we meet that forecasted demand, it will be the highest annual peak in 25 years.
Other days this week are forecasted to come close to that as well. As of Monday afternoon, the forecasted peak energy demands on Monday (48,967 MW), Wednesday (50,002 MW) and Thursday (49,327 MW) would also surpass the current third-place year. In 2007, the state’s peak energy demand was 48,615 MW.
Cal ISO has a robust and useful app, where users can find all of this information and track upcoming demand and supply forecasts, as well as look back on historical data. The information is also available online here.
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