Weathering the storm: Ensuring grid resilience in the face of extreme weather

Challenge

Extreme weather events and shifting weather patterns are putting unprecedented strain on the utility industry, threatening aging infrastructure and highlighting the urgent need for enhanced grid reliability and strength. At the same time, utilities are under increasing pressure from regulators and consumers to integrate risk and resilience into their investment planning to ensure reliability and mitigate economic impacts over the long term. Duke Energy—which serves customers across the Midwest and Southeast—understood that they needed more than a one-size-fits-all-solution to meet these challenges. The utility determined that the vulnerabilities created by regionally specific extreme-weather events urgently needed to be identified and quantified across its operations, and that a tailored roadmap was needed to address them.

Approach 

To help Duke Energy accomplish those goals, Guidehouse teams worked with the utility to conduct a Climate Resilience and Adaptation Study, a comprehensive initiative that focused on the company’s generation, transmission, and distribution system to assess vulnerabilities and develop a flexible framework for improving operational resilience across all of the territories that the utility serves. It was a first-of-its-kind assessment of the entire system, across all jurisdictions, of a vertically integrated utility.

The study incorporated projections and weather-pattern modeling across a roughly 25-year timeframe, from the present to 2050. Working closely with Duke Energy subject matter experts in discussions, interviews, workshops, and feedback sessions, Guidehouse focused on three critical priorities:

• Developing a methodological framework: To visualize threats to specific assets in particular locations, the Guidehouse team used downscaled weather data from the National Oceanic and Atmospheric Agency and climate impact forecasts provided by Jupiter Intelligence. These forecasts are based on coupled model interaction project (CMIP) models curated by United Nations researchers. That weather and climate data, in turn, was forecast for specific hazards and specific Duke Energy assets.
• Conducting a vulnerability assessment: Building on that framework, Guidehouse performed a detailed analysis of the potential impacts of extreme weather events on Duke Energy’s infrastructure and determined specific failure thresholds for each asset class, gaining a clear picture of threat exposure across its operations.
• Identifying adaptive actions: Equipped with detailed vulnerability assessments, the Guidehouse team was able to recommend concrete actions—both immediate and long-term—to address specific hazards affecting infrastructure assets. Those actions included design modifications and operational changes to boost resilience against extreme heat, high winds, and flooding. 

Impact 

Duke Energy has already begun to operationalize the insights yielded by the study, taking action to harden its systems against extreme weather. One of the early priorities has been protecting battery storage systems, which enable the utility to respond to demand fluctuations and, through the use of microgrids, provide backup power in case of outages. Knowing that battery storage systems are particularly vulnerable to floods, the utility has already implemented some of the adaptive actions highlighted in the study by ensuring system designs accommodate predicted flood levels. Typical industry standards employ a “100+1” provision, which requires that equipment be elevated one foot above the projected flood depth in a 100-year flood plain. Duke Energy is using data-driven insights to elevate selected sites above those levels, a precaution that has already protected equipment from recent storms that caused flooding exceeding the 100-year threshold. 

An example of these efforts is Duke Energy’s Powerline battery, which is being developed to serve the utility’s Florida service territory. The battery, a fast-responding resource that will enhance the overall reliability and resilience of the Florida electric grid, is in an area with known flooding risks. A hydrology study is being conducted to evaluate the project’s exposure to extreme storm events typically not included in FEMA flood studies. The study takes into account both riverine and coastally driven flood events, including hurricanes, and integrates a site-specific engineering model that includes all possible drainage areas contributing to the project site and surrounding areas. The rain-on-grid riverine model covers approximately 113 square miles. The study also provides site-specific results from three existing storm surge models. The results are being used to inform the final elevation of the site, which is to be set above the 500-year flood plain.

Last year alone, Duke Energy invested more than $4 billion to harden and modernize the grid. This included targeted undergrounding, reinforced flood barriers, year-round vegetation management, pole upgrades to steel and concrete in coastal areas, and self-healing technology, which instantly detects outages, isolates the problem, and reroutes power—often in less than a minute. Going forward, Duke Energy will continue to invest in these critical infrastructure assets with grid investments accounting for nearly half of its five-year, $83 billion capital plan. 

These data-driven, targeted investments—informed by the Climate Resilience and Adaptation Study and Guidehouse’s broad industry expertise and best practices—are helping translate better risk and vulnerability data into long-term resilience. For the customers and communities that Duke Energy serves, it means confidence that the utility is making the crucial investments to keep the power on when it’s needed the most.