There were rolling blackouts in California last Friday and Saturday for the first time since 2001. Back then people were so angry about it that they eventually recalled Gov. Gray Davis. This time around Gov. Newsom was quick to give a speech saying the blackouts were “unacceptable” and promising an investigation into what went wrong.

So what did go wrong? California’s energy grid is run by an organization called California Independent System Operator or Cal ISO. Cal ISO’s job is to turn various supplies of energy on or off and, if necessary, seek out energy from out of state to meet the demand for electricity in the state. On Friday and again Saturday Cal ISO simply couldn’t find enough supply to meet the demand so it called for a stage 3 emergency and ordered energy companies to simply turn off power to some customers to prevent the grid from flickering on and off for everyone. So the blackout wasn’t a surprise or the result of an equipment failure. It was an emergency response to a lack of supply.

Everyone agrees that the heat wave is what drove the surge in demand for power over the weekend. But Cal ISO had known about the heat wave in advance. So why couldn’t it find enough power to avoid a blackout. And specifically, why did the blackouts happen in the early evening as the sun was going down? That’s where the state’s green energy mandates come into it. From NPR:

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.

Yesterday the Wall Street Journal published an editorial going into a bit more detail:

Mr. Newsom is demanding an investigation, though he can start with his party’s obsessions over climate and eliminating fossil fuels. Even former Gov. Gray Davis admitted the culprit is the state’s anti-fossil fuel policies. “The bottom line is, people don’t want lights to go down,” he told Politico. “People also want a carbon-free future. Sometimes those two aspirations come into conflict.” They certainly do.

California’s Independent System Operator (Caiso) has been warning for years that the state’s increasing dependence on intermittent renewables, especially solar, is making it harder to ensure reliable power. Renewables currently make up about 36% of California’s electric generation, and Democrats have set a 60% mandate for 2030 and 100% for 2045…

Dozens of natural-gas plants that can ramp up power on demand have closed since 2013—enough to supply about four million households—so California is relying more on energy imported from other states when needed. In normal times it imports about 15% of its energy. But the Golden State’s neighbors are also experiencing heat waves, and many have also been replacing fossil fuels with renewables too…

The power outages will get worse and more frequent as the state becomes more reliant on renewables. The Public Utilities Commission (PUC) has directed utilities to triple their battery storage for electricity by 2026. But this won’t make up for the natural-gas and nuclear plants that are slated to shut down in the interim—or the state’s power shortfalls during the heat wave.

So it seems pretty clear what happened here. Because of the heat wave there was increased demand. California was able to meet that demand for most of the day Friday and Saturday but several reports note that, because it was cloudy during the day, solar generation was off a bit and as the sun began to set solar sources cut out. Cal ISO simply couldn’t find enough out-of-state sources to make up the shortfall and was forced to order blackouts. Clearly we need more reserve power generation capacity which isn’t wind or solar on hand for situations like this.

But the people pushing California toward 100 renewables don’t want to hear about extending the life of existing natural gas plants much less building new ones. For instance, NPR reports a Cal ISO board member says renewables aren’t the problem.

“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…

“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.”…

“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.”

He may be right about what it would take to reduce demand but how do you get people to do that exactly? California already has “flex alerts” which are basically media announcements asking people to use less power. Those were issued last week and obviously weren’t enough to prevent the blackouts. It’s not clear how doubling down on a plan that didn’t work last week is going to put us in a better position next time we have a heat wave.

One possible solution is more storage. Battery capacity could improve the state’s ability to use power after the sun goes down but batteries are expensive and have a relatively short life span. As the Wall Street Journal points out, it’s an expensive option:

According to the Energy Information Administration, the capital costs for a solar plant with an attached battery system run between 50% and 150% higher than for a new natural-gas plant. Natural-gas plants are still much less expensive after accounting for fuel costs, and they generally have a lifespan of 30 or more years.

These are all problems that need to be solved if we’re going to rely on increasing amounts of renewable energy. The blackouts last week were a wake-up call that we aren’t there yet as far as reliability goes. Hopefully the zeal for renewable energy will be tempered with some common sense moving forward, but that’s another thing that’s often in short supply in California.

Here’s a 6-minute edit prepared by the LA Times of Gov. Newsom’s speech on the blackouts Monday.