Lessons Learned: How Utilities Have Prepared for Hurricane SeasonAlex Forbes
The recent increase in extreme weather events presents major resilience challenges to electricity supply assets.
In any news story about extreme weather, close to the beginning, if not in the headline itself, will be the number of people left without power. Utilities are under pressure to develop an effective disaster recovery strategy, so that—when the crisis has passed—they can quickly clear away the debris, and residents can get on with their lives and businesses.
During last year's astonishing hurricane season, Texas and Florida saw how effective these strategies can be in the face of seemingly overwhelming destruction.
Hurricane Harvey was the most powerful weather system to impact Texas and Louisiana since Hurricane Katrina 12 years ago. It left around a quarter of a million people without power, yet, despite catastrophic flooding, most had their power restored within days.
In Florida, Hurricane Irma left millions of people without electricity. At first, there were fears that some might not be reconnected for weeks. "What distinguished Irma from past storms was its size," says Tim Drum, a meteorologist for Florida Power & Light (FPL), the third-largest electric utility in the US. "Irma was a vast storm—the size of Texas—that impacted all 27,000 square miles and 35 counties of FPL's service territory. Unlike previous storms, in which we could focus on restoring a particular region, responding to Irma required us to deploy our resources across the entire state."
"While this is the worst storm our company has faced," says Eric Silagy, FPL's president and CEO, "rest assured we were ready, having pre-positioned the largest restoration workforce not just in our company's history but in US history." At the height of the restoration work, FPL had 24,000 personnel involved, including 11,000 of its own employees and 13,000 workers from contracting companies and utilities across the nation and even Canada—thanks largely to a voluntary mutual assistance program that North American utilities have established.
A critical factor in the success of FPL's disaster recovery strategy is the experience it gained following Hurricane Wilma in 2005. FPL has since invested nearly $3 billion in making its energy systems "smarter, stronger, and more storm-resilient."
Moreover, in advance of Hurricane Irma's approach, FPL took the precaution of shutting down its two nuclear power plants, Turkey Point and St Lucie. It was also planning to power down some of its natural gas power plants in the path of the storm to mitigate damage and enable it to bring sites online faster after the storm.
With only a few exceptions, FPL was expecting to restore power to the 4.4 million people that lost it within two weeks of Irma's landfall. By September 26, 16 days after the storm made landfall in Florida, 99.74 percent of FPL customers had power.
There is widespread agreement in the scientific community that extreme weather events will worsen as the planet warms. An August 2016 report prepared for the Department of Energy by Benjamin L. Preston et al.—members of six national laboratories—warns that: "Climate change poses long-term challenges by changing the frequency, intensity, and duration of the weather events that represent the largest source of disruptions to the US electricity grid."
The report defines four elements that contribute to the concept of resilience by addressing risk management needs before, during, and after a threatening event:
There is an emphasis in the report not just on developing response options to mitigate damage and to recover from damage as quickly as possible, but also on learning from experience so that the system becomes more robust over time.
There is a danger that in striving to rebuild infrastructure as quickly as possible after a disaster, utilities may miss the opportunity to improve that infrastructure rather than simply restoring it to its previous state. Furthermore, robust infrastructure and assets need to be supplemented with policies and practices that streamline assessment and decision making, while enhancing coordination and communication.
The electricity system has multiple vulnerabilities at all links of the value chain. The vulnerabilities aren't just in the four main functions of electricity supply—generation, transmission, distribution, and end use—but also in fuel supply chains and the communications of the smart technologies that operators increasingly depend on.
The main vulnerability of generation assets caught up in extreme weather events is from flooding, whether caused by rainfall or by the storm surges whipped up by hurricanes. That was a lesson learned by Consolidated Edison when Superstorm Sandy ravaged New York in 2012; three of its power stations were affected. In a four-year, $1 billion plan that Con Edison then developed to provide a comprehensive storm defense system, numerous measures were implemented to mitigate water infiltration.
Fires are another danger. While shutting down an entire power grid would be both inconvenient for customers and potentially dangerous for hospitals and emergency services, taking down part of a power system could help prevent fires started when power lines get knocked down by high winds. A de-energized system can also pose less risk of damage when in contact with the ground than an energized system.
To get ahead of storms and prepare communities for fast recovery in the most effective way possible, investment must be made early in infrastructure.
Transmission and distribution networks, as we have seen recently, are vulnerable to storm damage and will benefit from hardening measures. Undergrounding, while expensive, can substantially increase system reliability and resilience to extreme weather. According to T&D World, as part of the $3 million it invested in its energy systems, FPL hardened more than 700 main power lines that serve critical facilities and services. It also cleared 150,000 miles of power lines of vegetation that could cause power outages; set a plan to inspect the company's power poles every eight years—with upgrades and replacements as necessary; and installed nearly 5 million smart meters and 66,000 intelligent devices to deal with power outages, from prediction to prevention and restoration when outages do happen.
For owners of long-lived power assets, the main challenge will be to balance the cost of adaptation against the need to maintain critical infrastructure that supports human well-being, economic growth, and national security.
Photo courtesy of Florida Power & Light Company.
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