Hurricane Beryl, the earliest Category 5 hurricane on record in the Atlantic, made U.S. landfall as a Category 1 storm on the Texas coast July 8. Moving through Houston, Beryl left more than 2.2 million homes and businesses without power. Massive flooding, debris, and downed trees and power lines made conditions hazardous. Days later, with hundreds of thousands in Houston still without power and coastal communities facing a 2-week restoration timeline, the area found itself in the throes of a dangerous heat wave. With heat indexes in triple digits, heat-related medical emergencies overwhelmed local hospitals, and residents’ food supplies were spoiling while many groceries and food banks remained closed.
Beryl aptly illustrates the amplifying impact of compound climate-related hazards and highlights the continuing need to evaluate the resilience of the electricity system to these events. Compound hazards are a type of climate extreme comprised of two or more climate drivers occurring simultaneously or successively with negative implications on environmental and human systems. EPRI recently released a report, generated by EPRI’s Climate READi team, to highlight the importance of characterizing compound hazards from a climate perspective and emphasizing the need to translate this information into power system vulnerabilities.
Hurricanes like Beryl already bring simultaneous impacts via damaging wind and flooding. Downed trees and power lines increased restoration times by cutting off access to affected areas. After landfall, a severe heat wave magnified the consequences of the initial event by increasing the need for electricity while the grid was compromised.
Beryl was not the only extreme weather to hit Houston this summer. A few weeks prior to the hurricane, 2 million people lost power when a severe thunderstorm dumped between eight and 12 inches of rain on the city, with high winds damaging buildings and toppling trees. Clean-up of storm debris was not complete on the first storm when the second storm hit.
Energy-relevant impacts to the power system from compound hazards generally fall into two categories – direct impacts from physical damage, such as those experienced during Hurricane Beryl, and indirect impacts to system operations that create resource adequacy challenges. An example of the former could include severe drought conditions in conjunction with high winds to drive wildfire spread. An example of the latter could include periods of low wind and cloud cover, often referred to as renewable energy “droughts,” which have the potential to create energy shortfalls on the system.
The Fifth National Climate Assessment finds broad agreement that compound events are a growing threat to society and critical systems. Numerous researchers have examined trends and projected changes in individual climate hazards and evaluated the potential impacts of these hazards on the power system. However, the impacts of compound hazards have received less attention and are fundamentally much harder to assess. Data availability remains an important limitation in studying these types of hazards due to small historical sample sizes and the need for data that preserve dependencies between climate variables.
Representing climate hazards, including compound events, in power system models and tools also faces technical challenges. Recent advances - such as modeling frameworks beginning to incorporate asset-specific climate vulnerability information into power system analyses - can serve as a starting point and may be extended to include compound hazards. An important first step is to capture a wide range of weather conditions that can impact system operations in a way that preserves the unique dynamics of these events. Most of these models do not explicitly include geographically specific information, which can make the direct translation of impacts from events covering wide areas difficult. Also, the models often have limited representation of chronology, which complicates the ability to assess longer duration events.
Cross-disciplinary collaboration, artificial intelligence, and machine learning can serve as approaches to studying and understanding compound hazards directly relevant to power companies. In addition, coordinated impact assessments and adaptation planning between researchers, power system operators, and local and regional government officials can result in a more comprehensive understanding of the vulnerabilities that exist across regions.
Resilience efforts focused on just one climate hazard may overlook potential increases in vulnerabilities to other climate events. The study recommends that consideration of compound hazards become a fundamental component of risk assessments and resilience planning in the power sector. Even a well-adapted system is not invincible. Five days after Hurricane Beryl blew through, the health and safety risks from extreme heat quickly supplanted the toll from the storm itself, demonstrating the initial event is not necessarily the one with the highest impact to society.