Up Close with California’s Power Grid Operator

August 28, 2019
Mark Specht
Senior Energy Analyst

I went on a tour of the California Independent System Operator.

“The who?” my parents asked me. “Never heard of them.”

I explained: “the California Independent System Operator – or CAISO for short – they operate the grid in most of California.”

“Huh,” they replied, somewhat puzzled, “I thought the utilities, like PG&E, did that.”

“Nope!” I said, being a totally unhelpful son and energy analyst, failing to explain further.

So let me do a better job of explaining the CAISO to you than I did to my parents.

What do Independent System Operators do?

Independent System Operators, or ISOs, are like air traffic controllers, but for electricity. Just as air traffic controllers supervise take-off and landing at airports and manage routes between airports, ISOs manage the flow of electricity on transmission lines and instruct power plants to turn on and off in order to match electricity supply and demand. Air traffic controllers don’t own the airplanes or the airports; likewise, ISOs don’t own transmission lines or power plants. Both air traffic controllers and ISOs are an independent third party that keep these complex systems operating efficiently and safely.

There are seven ISOs and RTOs in the United States (RTO stands for Regional Transmission Operator, which is very similar to an ISO). Together, these serve roughly two-thirds of the United States. For the large swaths of the country without an ISO/RTO operating the electric grid, the local electric utility is likely operating the transmission system and balancing electricity supply and demand. (So my parents were sort of right, except this isn’t the case in northern California!) Of all the benefits of having an ISO operate the grid, the most significant is the increase in efficiency, which helps ensure reliable and lower-cost electricity.

The CAISO started operating in 1998 when they opened their two California control centers. Today, the CAISO manages roughly 80% of California’s grid and nearly 26,000 miles of transmission lines, serving 30 million customers. The CAISO also operates numerous markets to facilitate the buying and selling of electricity and other services that keep the grid operating smoothly.

There are seven ISOs and RTOs in the United States, serving roughly two-thirds of the country.

Grid operators learning as they go

For the grid to work properly, electricity generation must exactly match electricity demand at all times – right down to the second! The grid operator’s job has always been to stay ahead of the daily changes in electricity supply and demand to keep the grid in balance. For instance, grid operators must anticipate and respond to weather changes that affect renewable energy production and electricity demand (e.g. cloud cover that reduces solar output and heatwaves that increase air conditioning use). Grid operators must also respond to unexpected power plant and transmission line outages.

Operating the grid has gotten considerably more complicated over time. Decades ago, grid operators had to consider the weather and the calendar to get a pretty good idea how much electricity people would be using the next day. The grid operator would tell coal and natural gas power plants to turn on to make sure there was enough electricity throughout the day. And that was pretty much it.

Nowadays, California has made significant investments in renewable energy. While wind and solar generate low-cost and emissions-free electricity, they only generate during certain times of day, and the CAISO has to fill in the gaps with electricity from other sources.

The CAISO has been learning as they go, figuring out how to integrate more and more renewables into the state’s grid as California strives to achieve its clean electricity goals. While ISOs and RTOs across the country have been steadily adding renewables to their grids, California is much further ahead, and the CAISO hasn’t had many examples to look to – they have been figuring it out on their own. The CAISO’s efforts have enabled them to operate at times with 78% of demand met by renewable energy.  This is an achievement reflecting a lot of learning.

Ramping up in the evening

Traditionally, grid operators have been most concerned about the “peak demand,” which happens on the hottest summer days when folks are blasting the air conditioning. But California’s grid operators are now more concerned with “evening ramp,” which is the time in the evening when the renewable generation (mostly solar) tapers out and other sources of energy must ramp up to meet electricity demand. The evening ramp is a yearlong challenge for the CAISO.

On the January 1, 2019, the CAISO broke their all-time evening ramp record: over a three-hour period, they ramped up by 15,639 MW. Considering that the peak demand in all of January 2019 was just under 30,000 MW, having the flexibility to ramp up by half the month’s peak demand in only three hours is not a simple feat.

A big evening ramp makes the grid operator’s job more difficult because not all resources can be ramped up to produce electricity that quickly. So California is implementing solutions to help ease the evening ramp. Energy storage, flexible demand, and diverse sources of renewable energy like geothermal and wind can all make the grid easier to operate. As California continues progressing towards its clean electricity targets, the state will need to double down on these solutions to make the transition go smoothly.

The biggest challenge

I can’t discuss challenges faced by the grid operator without mentioning cyber security, reportedly the CAISO’s biggest challenge. The CAISO computers are hit millions of times per month with attempted intrusions, and the CAISO must stay on top of the constant probing to ensure their networks remain secure. A security breach could have serious consequences (e.g. power outages). Suffice it to say, the CAISO takes both cyber security and physical security at their headquarters very seriously.

The control room

The CAISO control room in Folsom, CA is staffed 24/7/365 to keep California’s electric grid operating smoothly.

I visited the CAISO control room in Folsom, California this past July. The first thing I saw when I laid eyes on the control room was the probiotic ads on the TV. I thought, “Why do these blessed control room operators get to watch TV on the job all day long?” The answer, as I learned, is “situational awareness.” The control room operators need to know what’s happening in the outside world that might affect the grid, things like terrorist attacks or wildfires. So they monitor the TV news 24/7 (which is probably more a curse than a blessing) to stay on top of current events.

The people who operate the CAISO grid don’t have an easy job. No matter the time of day, the operations room is always staffed, and operators work 12-hour shifts in a windowless room. Tough job! It turns out many CAISO operators are ex-military folks who used to work on submarines (with no windows!). Their prior experience makes them a natural fit because they are used to working long hours and keeping a cool head in high-stress situations. When something goes wrong and the grid is out of whack, operators must be able to make good decisions on the fly to restore balance and keep the lights on.

Why you should care about the CAISO

For the most part, the CAISO flies under the radar, and most Californians are probably not even aware of its existence. But the CAISO plays a critical role in California’s electricity system. When California’s utilities add more renewable energy to the grid, the CAISO is the one who is figuring out how to utilize all that clean energy while keeping the lights on. When wildfire risk is high and California’s utilities de-energize transmission lines, the CAISO is the one who must figure out how to minimize the impact and keep the lights on.

The bottom line is, on a day-to-day basis, the CAISO is the organization responsible for keeping the lights on in most of California. And they do this despite all the challenges that come their way.