Managing the July 2024 heat wave with our partners in California and the West

By Dede Subakti, VP, System Operations | 07/15/2024

Extreme weather like the extended heat wave California and much of the West have experienced this July can pose a reliability challenge for even the most resilient electric grid. Such prolonged heat events can also affect everyday life and cause life-threatening conditions. And triple-digit heat waves persisting like this one over many consecutive days can likewise overtax energy systems with an increased risk of power outages and reduced generation capability due to increasing temperatures.

We at the California Independent System Operator (ISO) take seriously our mission to keep the power on for more than 30 million people and want to share this brief overview of how the bulk electric system performed over the past two weeks.

California’s power grid held up against prolonged record temperatures because of new clean energy resources, more battery storage, and enhanced coordination with state government – and the grid was also able to export energy to other states in need during this heat wave.

Thanks to the state’s accelerated pace of new resource procurement that has added significant capacity to the grid, continued enhancements to our technology systems, the rapidly growing and high-performing battery fleet that allows us to dispatch power captured during the day from solar, and enhanced communication and coordination, the ISO and our partners in California and the region were able to work through this latest heat event with no power disruptions.

We must remain vigilant when dealing with Mother Nature and the growing impacts of climate change. Summer can always present challenges in managing the grid and we know there is always more work to be done to strengthen reliability. But any way one looks at it, the nearly two-week-long heat wave of July 2024 has been a success story for the state’s power system. It also shows how far California has come in just the past several years.

The demand for power on the grid operated by the ISO peaked during the recent event at 43,969 megawatts (MW) on Thursday, July 11 at 7 p.m. That day brought the hottest temperatures to California and much of the West, but as the ISO moved through the operating day, the demand was well within our available capacity. We were able to meet it with room to spare.

Thanks to procurement authorized by the California Public Utilities Commission and other local regulatory authorities, California has been adding clean resources to the grid at an historic rate. In just the last two years, more than 11,000 MW of clean energy has been brought online. The battery fleet on the grid, which performed well throughout the heat event and helped meet demand during the evening when solar was declining, is approaching 10,000 MW.

California has been adding clean resources to the grid at an historic rate. In just the last two years, more than 11,000 MW of clean energy has been brought online.

On the more expansive bulk power system known as the Western Interconnection, which serves more than 80 million people and spans 1.8 million square miles in the West and parts of Canada and Mexico, demand hit a new all-time peak of 167,988 MW on July 10 at 5:10 p.m. That surpassed the prior record of 167,530 MW on Sept. 6, 2022.

During that 2022 heat wave, the ISO called Flex Alerts urging consumers to voluntarily conserve electricity on a record 10 consecutive days. We also reached our all-time system peak demand of 52,061 MW on Sept. 6, 2022 and used every available tool to meet that load. This year, we have gotten through two weeks of triple-digit heat with no Flex Alerts. For the ISO and RC West, which serves as reliability coordinator for us and a total of 42 balancing authority areas in the West, we also have had no emergency notices, known as Emergency Energy Alerts, and enough power to meet demand without any outages.

Additionally, throughout the July 2024 heat wave, the ISO’s Western Energy Imbalance Market continued to be an effective tool in helping to balance supply and demand in the wider Western footprint by enabling energy transfers across the region. For example, on July 8 and 9, the ISO exported 8,000 MW of energy, and became a net exporter during several hours. The ISO market also honored all high-priority exports and wheel-through transactions for regional energy providers that use our transmission network to send power to their customers.

The ISO’s Western Energy Imbalance Market continued to be an effective tool in helping to balance supply and demand in the wider Western footprint by enabling energy transfers across the region.

Managing the system during these stressed conditions takes a good deal of planning and coordination with load-serving entities and many of the state agencies, including the Governor’s office, California Energy Commission, California Public Utilities Commission, and California Department of Water Resources. Armed with strong planning and coordination, we executed our summer playbook used as a guide to help manage and communicate during potentially stressed conditions.

Starting on July 2 with triple-digit temperatures across much of California and the West, our grid operators began taking actions to help meet demand and maintain reliability. We stayed in regular communications with our state agency partners on all aspects of weather conditions and the availability of resources. At the same time, we were also closely monitoring the growing wildfires in the area for potential impacts to the transmission system and resource production.

Also on July 2, we declared a Transmission Emergency for part of the Northern California region due to wildfire activity affecting local area transmission facilities. The declaration allows grid operators to tap into mitigation measures to relieve impacts in the area.

One day later on July 3, we issued a restricted maintenance operations order in our footprint that cautioned utilities and transmission operators to avoid taking equipment offline for routine maintenance, assuring that all generators and transmission lines were available during these higher demand periods.

On Tuesday July 9, we elected to activate the long-start resources within the state’s Strategic Reliability Reserve program as a precautionary measure in the event additional energy was needed during the anticipated peak of Thursday, July 11. However, with no supply shortfalls and enough resources to meet demand, we did not need additional energy from these reserve assets to maintain reliability.

We also got excellent help from both price-responsive demand response programs and state demand response programs that contributed to a reduction in demand from consumers across peak and net peak hours.

Throughout the heat wave, the ISO maintained close coordination with California state agency partners to help mobilize various state programs designed to provide grid support during extreme weather events and ensure consistent communications. Load-serving entities and those that administer demand response programs also worked closely with the ISO throughout the heat wave to coordinate additional grid relief.

All in all, our operators and partners across the region stepped up and kept the power flowing throughout a heat wave of historic proportions. I am proud of the work everyone did and grateful for all the support and coordination that helped us get through it.

In these types of events, our customers and the public at large are already managing challenging conditions, trying to stay cool and safe as temperatures seem to regularly set new records. We understand the critical role we play in those efforts. It really does take a village to keep the power on during these types of historical, prolonged heat events. We all have a role to play and we always strive to do it well. We will continue to work hard, learn and seek to improve from every experience and make the grid as resilient and reliable as we possibly can.