In August, California’s grid operator (CAISO) was forced to institute rolling outages across the state as a historic heat wave affected much of the Western United States. This was the first time that there have been outages at this level in the state since the energy crisis of 2000-2001 was sparked by market manipulation that led to supply shortages and utility bankruptcies.
Many factors at play in California have led to these recent events, and it will be months before the various drivers of the outages can be fully assessed. However, some observers have jumped to an early conclusion that the state’s aggressive clean energy goals are somehow to blame, and that renewable energy is a primary cause of the outages.
Such speculation is premature, incomplete and almost certainly incorrect. More important, such a narrative also leaves out the fact that clean energy can present an opportunity, not pose a threat, to grid security and reliability. The ongoing transition to clean energy is not only critical to address the existential threat of climate change, but if properly managed, also can materially improve the resilience of the power system to extreme weather and other threats.
Climate change is driving extreme conditions
It’s no accident that these blackouts are happening. The entire West is suffering under blistering heat. July was tied for the second-hottest month on record and during the August heat wave Death Valley hit 130 degrees Fahrenheit, the highest recorded temperature in more than 100 years.
Along with the heat, recent weeks have seen other extreme weather phenomena across the country. These include the August "derecho" wind storm in Iowa and Illinois which hit speeds of up to 106 miles per hour and flattened cornfields, as well as a series of particularly powerful tornadoes on the East Coast spawned by Hurricane Isaias. Both events have left hundreds of thousands of customers without power for days or longer.
July was tied for the second-hottest month on record and during the August heat wave Death Valley hit 130 degrees Fahrenheit, the highest recorded temperature in more than 100 years.
As climate change progresses, we can expect to see more of this. A grid designed for reliability in the face of 20th century extreme weather is proving inadequate to address worsening 21st century events. Decarbonizing our economy to avoid the worst effects of climate change has been compared to rebuilding a plane while flying it and extreme weather is causing increasing turbulence along the way.
Fossil generation contributes to grid outages
When looking at what caused the blackouts in California, we have to examine both the whole system and the role of individual power sources. On a Friday and Saturday in mid-August, gas generators tripped offline, which contributed to outages along with near-record electricity demand, a reduction in wind output, limited import capacity and several other factors.
There is no perfectly reliable source of power, and these are only the latest in a string of forced outages at fossil fuel and nuclear power plants over the last few years during extreme weather events. Even when they don’t go offline, thermal generators such as coal, gas and nuclear plants have lower capacity during heat waves and may run into operating constraints when the water needed to cool them becomes too warm to effectively perform that function.
In California, solar has continued to contribute as expected to meeting peak demand. However, on Aug. 14, electric demand remained high as the sun set. This is expected and planned for, and a variety of resources including gas plants and imported power ramped up at this time to take over.
Exhibit 1: Generation on the California Independent System Operator Grid, Aug. 14-17
As the state brings online more batteries, these will contribute to meeting evening peak demand. Currently, a number of very large battery projects, such as the mega-project in Moss Landing, are under construction but not yet online.
In July, California’s grid operator reported that 216 MW of batteries are in commercial operation but noted that if all projects in its queue are completed on time, this will increase to 923 MW by the end of this year. By comparison, CAISO reports shedding 1 GW in two separate 500 MW waves Aug. 14.
This suggests that the batteries currently planned could have played an important role in preventing these outages and are poised to play a growing role in the diverse portfolio of resources needed to maintain reliability.
The opportunity for clean energy to improve grid reliability
At the same time as the United States grid is accommodating rapid technological shifts in renewables, storage and other technologies, climate change and other major threats to grid security are growing in likelihood and impact. Thus, there is now a once-in-a-generation need and opportunity to reimagine our approach to grid resilience for the 21st century in a way that leverages improving technologies while addressing a fundamentally different risk environment than existed as the grid grew in the 20th century.
Two emerging principles for 21st century grid resilience are relevant to the present situation. First, there is an opportunity to better prioritize electricity service during outages, including for customers reliant on medical equipment and emergency responders, so that these critical loads are not subjected to indiscriminate rolling outages. For example, a utility in Colorado is prioritizing investment in targeted energy efficiency and demand flexibility technologies, as well as advances in grid control technologies that can route power to critical loads, that together can mitigate outages caused by power supply limits.
Second, grid planners should abandon the idea that a centralized, fossil-dominated resource portfolio, an approach developed to ensure reliability during the last century, is adequate to meet new resilience needs in the 21st century. Current events demonstrate that grid operators need a diverse portfolio of well-integrated, flexible resources for maintaining grid reliability through climate-driven extreme weather events.
The opportunity remains to create a system of clean generation and responsive demand that both mitigates blackout risks and addresses the fundamental problem that put us in this situation: climate change.
No silver bullet for reliability
No single resource or technology can prevent blackouts by itself. Instead, different types of resources provide essential services across geographies and at different time scales. Solar PV is critical for meeting the total peak in the middle of the day, while battery storage can help meet fast-ramping and peak demand later in the day.
Other dispatchable supply resources, including carbon-free green hydrogen under development in California and elsewhere, are valuable contributors to managing the grid through stress. So are dispatchable demand flexibility resources. Distributing these supply and demand resources across a broader grid will make the system more robust to local variation.
The historic heatwave affecting the Western United States has created big problems for the grid, but nothing's inherent about any resources within the system that made them unable to meet these challenges. Rather, it’s clear that we just didn’t have enough of them. The opportunity remains to create a system of clean generation and responsive demand that both mitigates blackout risks and addresses the fundamental problem that put us in this situation: climate change.
California, among other leading states, is on its way to having a system of supply- and demand-side resources distributed across the region and integrated through a networked transmission system that can meet grid demands without making extreme weather worse. But we need to move strategically and get the right solutions online in the right places, and much more quickly. In other words, to address both near-term reliability threats and emerging climate risks, we need to move both more carefully and faster.