By Eric Barendsen
The California Independent System Operator knew they had a problem; it was one they had been predicting for at least a year.
After attending a September 2019 presentation, Administrator and CEO Mark A. Gabriel discussed with WAPA the shortages CAISO predicted would come: a capacity shortfall of 2,300 megawatts on their system by the summer of 2020.
“The challenge California now faces is the problem that the entire Western Interconnection will soon be facing, and that is how to maintain grid reliability as coal and gas powerplants are retired and replaced by variable sources like wind and solar," said Gabriel. “WAPA's evolving role is even more important in a world of increasing renewables because hydropower can be ramped up and down as needed."
A steep hill to climb
The emerging struggle in meeting California's demand would come from increased early-evening ramping needs—rapidly firing up enough dispatchable generation to keep the grid stable—and the timing of daily peak demand shifting from afternoon to evening in the summer months.
CAISO faces an increasingly steep evening ramp when demand spikes around 6 p.m. as people crank up their air conditioners and dinnertime energy use while California's abundant solar production drops off with the setting sun.
“Historically, California has relied on non-renewable energy sources, such as natural gas and imports from the north, to meet their evening ramping needs," said Senior Vice President and Sierra Nevada Regional Manager Sonja Anderson. “But over the past year, California retired 4,000 MW of coal and natural gas generation, replacing it with solar and wind."
Add to that a dry hydrological year and a record-setting heatwave, which at 130 degrees topped the highest temperature previously recorded in Death Valley, and the perfect storm CAISO had described hit the system in the middle of August.
Facing the facts
According to weather forecasters, the mid-August heatwave in the Central Valley would last up to eight days with highs consistently above 100 degrees.
On Aug. 12, CAISO declared restricted maintenance operation for Aug. 14-17, which required generators and transmission operators to postpone planned outages and ensure all grid assets were available for use.
On Aug. 13, CAISO began taking the additional step of issuing statewide “flex alerts," calling on businesses and residents to curb their energy use to reduce demand. The measures included turning off unnecessary lights, using major appliances before 3 p.m. and after 10 p.m., and setting air conditioner thermostats to 78 degrees or higher.
As feared, on Friday, Aug. 14, at approximately 3:30 p.m. Pacific time, CAISO issued an Energy Emergency Alert Level 2, a status not seen there since the energy crisis in 2001. Level 2 means that CAISO has implemented all potentially mitigating measures and cannot meet demand, requiring it to intervene in the market by ordering powerplants online.
“Fortunately, WAPA's real-time merchants and dispatchers were prepared for this scenario," said Supervisory Power System Dispatcher Marc Desmarais. “We were ready to help when CAISO indicated that an Energy Emergency Alert Level 3 was imminent."
In coordination with the Bureau of Reclamation, WAPA's control centers in the Rocky Mountain and Desert Southwest regions, its real-time merchants in Montrose, Colorado, and CAISO all agreed to a plan of action.
Beginning at about 5:30 p.m., Hoover Dam generation ramped up to support CAISO's call for assistance. Hoover Dam pumped about 260 megawatt-hours onto the Southwest power grid through 9 p.m.
According to energy experts, CAISO's call for assistance came too late to avert what happened next. At 6:36 p.m., CAISO declared an Energy Emergency Level 3 and directed utilities to implement rotating outages to protect grid stability, initially ordering 500 MW of load offline. By 7:03 p.m., CAISO ordered another 500 MW out of service as the blackouts rolled across the state.
Situated farther north on the Colorado River, Glen Canyon Dam ramped up to support California's energy need as well, providing about 500 MWh between 7 p.m. and 1 a.m. Aug. 15-16.
“We have tested this scenario in the past and from an Operations standpoint it was efficiently carried out," said Desmarais. “We credit our great marketers, our outstanding dispatchers and Glen Canyon Operations' adaptability for our successful response," he said.
Fortunately, by :54 p.m., it had cooled off enough for CAISO to lift the emergency declaration and power was quickly restored statewide. Reclamation and WAPA again provided assistance to the extent possible during the emergency declaration the following day. Delta breeze or bust Saturday, ug. 5, CAISO was forced to issue another Level 3 emergency, citing a trio of issues: high demand due to the heatwave, an unplanned 470-MW powerplant outage and lack of nearly 1,000 MW of anticipated wind power.
“For those of you familiar with the Central Valley, one of the greatest treasures we speak of is 'the delta breeze,'" said Anderson, referring to the Sacramento-San Joaquin Bay Delta. “No matter how hot it gets in the afternoon, you can always count on sitting outside in the evening with a cool breeze while sipping on your favorite beverage of choice."
The August heatwave was unusual, however, in that the cool breeze off the delta never materialized, and California's legion of wind turbines sat largely idle during the peak hours they were needed most.
Calling for backup
That weekend, California Governor Gavin Newsom's office took creative measures, such as enlisting roughly 300 MW of distributed battery storage and reaching out to the Navy and commercial ports in California to request that they use on-ship electrical generation instead of drawing on the overburdened grid.
On the morning of Sunday, Aug. 16, Anderson and her team hopped on a call with representatives from the governor's office and cabinet who were looking to state and federal water and power agencies to reduce load and make emergency resources available to the California grid.
Reclamation and the California Department of Water Resources worked together to curtail pumping in the Sacramento-San Joaquin Bay Delta, freeing up nearly 1,700 MWh for other uses. To boost available resources, Reclamation and WAPA joined forces Aug. 14-19 to generate and transmit roughly 5,400 MWh in response to California's energy emergency.
Vice President of Power Operations for the Colorado River Storage Project, DSW and RM Jon Aust said he was proud to be part of WAPA and this industry during the response, particularly on two fronts.
“First is the speed at which WAPA Power Operations and Power Marketing staff jumped into action when the call for emergency energy was made, and second is that WAPA was one of many who ensured that these emergency situations were mitigated by delivery to those utilities in need," he said. “These two facets were a testament to the community that has been built in the industry and across the Interconnection."
Reclamation generated the power using its fleet of federal hydroelectric dams in the West, including, among others, 18 dams in the Central Valley Project in northern California; Glen Canyon Dam in Page, Arizona; Hoover Dam on the border of Arizona and Nevada; Morrow Point Dam in western Colorado; Davis Dam in Arizona; and Parker Dam in California.
The central locations of the Glen Canyon and Hoover dams, especially, made them ideal for supporting much of the Western Interconnection in such a scenario.
WAPA then transmitted the energy via its high-voltage transmission system into CAISO's service territory, while continuing to reliably serve WAPA's customer loads. SN provided more than 3,300 MWh, while CRSP provided nearly 1,900 MWh and DSW provided more than 200 MWh.
“Based on Reclamation's water schedule, we regularly sell into CAISO, so for [SN], it was not much different except to maximize the sales to support CAISO," said Vice President of Power Marketing Arun Sethi.
In some cases, WAPA was able to offset this generation and continue to meet its customers' demand by increasing hydropower output from other dams to provide power to local areas.
On Sunday, Aug. 16, Governor Newsom called upon CAISO, the state's generators and consumers to do everything possible to ensure California avoided additional rotating blackouts. He ordered an investigation complete with recommendations on how to fix the problems exposed by the strained system without impacting the state's renewable energy goals.
Continued high temperatures into early September forced CAISO to declare Level 2 emergencies four more times over three weeks, but the state managed to avoid rolling backouts thanks to the conservation efforts of consumers and better management of generation resources.
“As a lifelong California resident, I was proud to work for an agency that was part of the solution and helped California keep the lights on," said Anderson. “Going forward, grid managers will have to adapt quickly to the operational challenges they face in terms of the steep ramps, oversupply risks and decreased frequency response inherent in balancing high levels of renewables."
The value of hydropower
WAPA's response to this emergency underscores the fact that hydroelectric dams remain crucial sources of reserve energy during system emergencies, as they can quickly dispatch a large amount of electricity onto the grid.
WAPA and Reclamation have plans in place with a number of utilities to provide emergency power from federal hydroelectric powerplants when the time comes.
“Hydropower is the ultimate generation source, providing both grid stability and low-cost and renewable energy, which is a combination not present in any other form of electric generation today," Gabriel recently wrote in Public Utilities Fortnightly. “Hydropower is key to a low-carbon future while maintaining the same electric reliability our lives and economies depend on."
Note: Barendsen is a public affairs specialist.