Scorching heat across the Western United States has left California scrambling to avoid rolling blackouts, as air conditioners send electricity use soaring.
Some people blame the power outages on California's reliance on solar power, which drops off when the sun sets. But energy experts say state officials failed to prepare adequately for high temperatures, despite the fact that California's own scientists and regulators have warned that increasingly common heat waves driven by climate change would stress the electricity grid.
"You can't control the weather, but you can prepare for the weather events," California Governor Gavin Newsom said. "And let me just make this crystal clear, we failed to predict and plan for these shortages."
The California Independent System Operator runs most of the state's grid, the system of transmission lines that takes electricity from power plants to communities. As temperatures crept above 110 degrees in some parts of the state over the last week, California ISO knew the end of each day would be the toughest.
When the sun sets, the state's fleet of solar farms turn off. With the state's growing clean energy mandates, renewables have become a significant source of energy, reaching up to 80 percent of the supply during the day.
Normally on hot days, California can import electricity from other states to fill in the gap as solar drops off, in addition to using natural gas power plants and other sources. But the widespread heat wave across the West means other states have little to share.
On top of that, a drier winter in California means hydropower dams are producing less electricity this year. The high-humidity heat wave created cloud cover, which reduces how much solar farms generate. And high temperatures cause fossil fuel power plants to run less efficiently, reducing their output.
The grid operator needed more electricity to cover the shortfall. "We are scouring every corner of our world," Steve Berberich, CEO of the grid operator, said in a midday briefing on Monday. "We loathe cutting off power and do it as a last resort."
But Berberich also blamed a lack of preparation by state regulators.
"The load forecast needs to reflect the realities of climate change," he said. "It's getting hotter."
Preparing for extremes
The California Energy Commission, the state's energy planning agency, runs a complex model to forecast how much power the state will need every summer under different weather conditions. Then, the state's electric utilities are on the hook for ensuring that electricity will be available.
But the weather conditions the state plans for are fairly common, not the extreme events that would test the electricity grid. The weather scenarios the Energy Commission uses for its electricity forecast are chosen by regulators at the California Public Utilities Commission.
Under their scenario, the state uses a 1-in-2 year weather event, something that might happen every other year. The heat wave California is now experiencing is more rare, potentially a 1-in-10 year event. Climate change threatens to make such heat waves more frequent.
"The last few years in California has been one giant climate change wake up call," says Severin Borenstein, University of California Berkeley economics professor and board member at the California Independent System Operator. "The wildfires and heat storms have combined to make it clear that the climate is changing and it's changing in ways that are very disruptive."
Some argue a 1-in-5 year event should be the benchmark. In both 2019 and 2020, California's grid operator warned that the electricity supply was extremely vulnerable to those kinds of major heat waves, especially ones that affect neighboring states.
"It's not clear to me that we're planning for more and more heat waves just like this one and we really should be," says Mark Specht, an energy analyst at the Union of Concerned Scientists, an advocacy group.
To deal with major heat waves, California could also have more electricity available as backup, in case it's needed. Right now, the state mandates an extra 15% in reserve to serve as a buffer, if the peak demand is higher than expected.
"More uncertainty almost certainly means that we should be being more cautious, which in this case means carrying more reserves," says Borenstein. "I think that is a lesson we are going to take away from this."
Regulators at the CPUC say they plan to examine what led to the blackouts.
"The CPUC has already made rule changes and modifications to the forecasting to adjust for changes in imported electricity that largely go into effect in 2021," CPUC spokesperson Terrie Prosper said in a statement. "As the Governor has directed, we and our sister agencies need to investigate this thoroughly to understand the how and why of the supply deficiencies that began on Friday."
Still, building more new power plants to fill the gap on the very hottest days could prove expensive. Solar power is expected to keep growing to reach California's goal of getting 100% carbon-free electricity by 2045. But that means other solutions need to work well at the end of the day, when solar drops off and power demand is high.
"I don't think this is the fault of solar at all," says Borenstein. "I think it means that we have to take a new planning approach."
Instead of making more electricity, one option is to simply reduce demand on hot days. The state already has voluntary programs where homeowners and large commercial and industrial facilities pay lower electricity rates, in exchange for agreeing to reduce their power use on very hot days. Private companies, like OhmConnect, also enroll homeowners to reduce their use on demand.
"Air conditioning is a huge amount of the load in California on very hot days," says Borenstein. "And so if we could get people to just reset their air conditioning four degrees warmer, we would probably be able to get through even the very tough Monday and Tuesday of this week."
Using giant batteries and other ways of storing electricity will also play a big role, since the state has mandated more installations. The idea is that extra solar power or other energy can charge the batteries when demand for power is low, so they'll be ready at the end of the day when demand is highest.
Some have called for extending the lives of aging natural gas power plants in California to shore up the state's energy supply. After the state's 2001 rolling blackouts, a fleet of new natural gas power plants was built.
Governor Newsom has said boosting fossil fuels would be contrary to the state's climate change goals. Given that climate change is making heat waves more frequent and intense, burning more fossil fuels to deal with them would be counterproductive.
"The solution is definitely not more natural gas power plants," says Specht. "Really if anything, this is an indication that California should speed up its investments in clean energy and energy storage."