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Climate and Environment

Power Up! How We Avoided Critical Blackouts During The Last Heat Wave And Why It Matters

A photo illustration shows a background of electric power infrastructure with an Apple iPhone showing an Emergency Alert notification from CalOES urging the public to conserve energy to protect health and safety.
Unprecedented heat waves are on the rise as the climate gets hotter. But experts say the country's heat warning system may be leading the public to underestimate the dangers.
(Patrick T. Fallon
AFP via Getty Images)
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Now that the weather’s cooled down, it’s easy to forget that 10-day heat wave in early September, when we came close to rolling blackouts.

About Those Outages

A report recently released from the California Independent System Operator (Cal ISO), the agency that oversees the power grid, explains how the outages were avoided. Among the main reasons are:

  • The public heeded the call to conserve energy when that text alert hit phones. 
  • A dramatic expansion in battery storage over the last two years helped store solar energy after the sun went down.
  • Increased coordination between grid operators across the West allowed California to import needed power from other states less impacted by the heat wave. 

Why Increased Battery Storage Matters

Solar power goes down with the sun…but batteries can store that power. In 2020, the last time there were rolling outages, California had just 250 megawatts of battery storage online.

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Now, the state can store 3,500 megawatts for several hours at a time…enough power for some 2.6 million homes (however, this number can fluctuate depending on the time of year, time of day and other variables.)

“Across that heating event, battery storage really proved its worth,” said Elliot Mainzer, who heads Cal ISO.

Mainzer said maintaining the pace of that buildout is an unprecedented challenge. He estimated the state needs another 120 gigawatts of power by 2040to support increasing electrification in the effort to unhook from fossil fuels, the burning of which to power homes, cars and industry is the biggest single cause of global heating.

How Much Power Is In A Megawatt?
  • There are 1,000 megawatts in a single gigawatt. One megawatt equals one million watts, or 1,000 kilowatts, roughly enough electricity to serve the demand of 750 homes at once, according to Cal ISO. One caveat: the number of homes powered by a megawatt can fluctuate quite a bit because electricity use varies depending on the time of year, time of day and other variables.

What We Need To Do To Get Off Fossil Fuels By 2045

If California is to stay on track to get off fossil fuels by 2045, the California Energy Commission estimates the rate of building battery storage needs to increase nearly eightfold.

Furthermore, the physical transmission lines needed to get that clean power where it needs to go can take 10 to 15 years to come online, Mainzer said.

Something else that helped with the heat wave this time around: the extreme heat wasn’t quite as broad-reaching as it was in 2020, allowing the state to import needed energy from states less hard hit.

“We were very fortunate during that event that, while it was extraordinarily hot here in California and in Nevada and other parts of the West, it wasn't quite that hot, relatively, in Arizona and the Pacific Northwest,” Mainzer said. “To be able to trade energy and move power around and take advantage of the transmission, connectivity and resource diversity that exists across the West…that really helped all of us maintain reliability.”

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Some Roadblocks To Consider

But global greenhouse gas emissions continue going up, and heat waves are only projected to get hotter, longer and broader geographically in California and around the world.

Mainzer said grid operators are preparing by looking into ways to incentivize consumers to use less energy, automate energy use through smart meters, and feed the grid with their own excess energy from electric vehicles or rooftop solar panels.

UCLA engineering professor Rajit Gadh said the million electric vehicles in California today alone could be their own massive battery in conjunction with large-scale renewable energy run by utilities.

Back in 2009, his team at UCLA demonstrated in a years-long study how electric vehicles could serve as batteries for the grid.

“The person who is consuming is now producing energy and it's happening more and more,” Gadh said. “Now the question is, how do you make everything work together?”

Climate Emergency Questions
Fires. Mudslides. Heat waves. What questions do you need answered as you prepare for the effects of the climate emergency?