Among the many concerns about how to keep electricity flowing reliably in the coming decades is how prepared the grid is for longer stretches of hotter days — when the temperature stays hot enough to keep equipment (or people) from being able to cool down on their own.
An analysis by ICF projects that the number of Americans that will be affected by heat that could significantly impact energy systems will increase from 19 million today to more than 78 million by 2050. ICF defines these conditions as 48 or more days per year where the average daily temperature exceeds 86 degrees Fahrenheit. The areas most likely to see increases in the number of energy-impacted heat days are across the southern and south central U.S., with parts of Texas and Florida expected to see the biggest increase.
The ICF report proposed several suggestions for how utilities can mitigate the potential effects of this expected energy use, especially among community members that already face a higher energy burden. Actions include determining which parts of your service area face the highest risk amid prolonged heat, seeking community input on convenient places to locate cooling centers, educating and supporting building owners on passive cooling measures, and focusing shade tree programs within higher-risk communities.
Recent news has highlighted the potential concerns related to if widespread power outages occurred during such heat waves, underscoring the importance of electricity to public health and safety. These stories have also called into question how prepared utilities are for keeping the electricity flowing throughout the summer. Here’s how public power utilities in some of the hotter parts of the U.S. have been and continue to prepare for whatever the future holds, and how they are solving some reliability challenges.
Swings and Sag
The Imperial Irrigation District serves one of the hottest parts of California, and the country, serving about 160,000 electric customers across the southern inland valley of the state, down to the border with Mexico.
“High temperatures are our main issue,” said Paul Rodriguez, deputy energy manager for IID, which serves the desert area that has seen highs reach almost 130 degrees Fahrenheit in recent years. “All year we are prepping to get ready for summer. It isn’t just stress on our electric grid, but on generation, which is a challenge on its own.”
In addition to the extreme heat, IID’s service territory experiences severe wind events and monsoons that can knock out key portions of the grid, including transmission.
With these conditions, Rodriguez stressed that IID recognizes the need to take reliability seriously, “it’s particularly a life and death situation because of the extreme temperature.”
This commitment is behind IID’s new Coachella Valley Energy Resilience Initiative, a three-part project that includes hardening transmission, improving infrastructure, and securing portable generators. The $38 million initiative received significant funding from federal grants, including FEMA’s Building Resilient Infrastructure and Communities (BRIC) program and the Department of Energy.
Rodriguez said that IID’s system is mostly temperature-based and has a very low load factor. He said that while its peak load is above 1,110 MW, the average is around 400 MW. So, while the system needs to be prepared to handle over 1,000 MW, it needs much less energy most of the year.
Properly accounting for this swing is a challenge, as is having efficient operations with a population that is very disbursed across the service territory. “Given the rural areas [we serve], it takes time to get out there, there’s a cost to drive out, and trying to find a trouble area is a challenge. But the best defense is a good offense, that’s what we’re shooting for,” with the initiative, said Rodriguez.
“The challenge when we do design and transmission is to account for the heat — we see higher strain in conductors, which translates to sag,” explained Rodriguez. To help, IID is adding more structures to shorten the distance between towers, including installing anti-cascading poles every mile, which are also rated to withstand higher winds.
“Our goal is to deliver reliable energy, and we pride ourselves as being one of the lowest cost utilities in California, and we want to keep it that way,” added Rodriguez. He noted that the median income across the county is one of the lowest in the state, and that the service area has many rural, disadvantaged communities. The federal support for the effort provides a critical investment for these communities.
Another game-changer for reliability, said Rodriguez, is having advanced metering infrastructure, which can better pinpoint outages and help in quickly dispatching field crews. IID is also looking at deploying some “self-healing” switches as well as an advanced distribution management system.
On the demand side, IID has been running a program that provides free shade trees to residential customers for a few years, which it this year expanded to nonprofit commercial customers as well.
“We have a system that is stressed out at times,” said Robert Schettler, public information officer at IID, who noted how the effort is one of several to encourage customers to curb energy use where possible. “It is pretty hot here, so if you can block the sun from your house, it can go a long way.”
Schettler also said that IID offers energy saving tips on its website and at community events and does energy audits focused on how customers can conserve energy and stay comfortable in the hot summer.
This push to conserve is also coming at a time when electrification is accelerating. Despite a mandate in California for new homes to have solar installed, IID has continued to see about a 1.5% annual growth in load. Plus, the state has mandated that all vehicles move to be electric by 2035, which will lead to even more growth.
“We are vertically integrated, so we control our generation, load, and act as a balancing authority. All that responsibility is on us,” added Schettler.
A Way of Life
In Florida, Michael Poucher, the director of electric utilities for the city of Bartow, said that while the system hasn’t seen any marked increase in load from air conditioning, the peak demand associated with higher heat has been starting earlier in the year and going later.
Poucher recently moved to Bartow from Ocala, Florida.
“Florida has always been hot, AC load is just a way of life,” he noted. The expectations around energy usage from air conditioning remain predictable, but the sudden cold snaps can cause problems, said Poucher, since most customers rely on electric resistance heating that can be less predictable in terms of demand.
Still, he said the summer peak days in Bartow see anywhere from a 30% to 40% increase in system load compared to the demand on mild winter days.
“If it gets hotter, we may see some increase in load, but at this point in time, we aren’t anticipating a huge change in the way we do things,” he added.
The bigger concern with increased load, said Poucher, is how the extended higher use will mean customers will see higher bills for more months. On the demand side, Bartow offers incentives for customers to better insulate their homes, whether by adding insulation to their roofs or in getting more energy efficient AC units.
The extended timeframe for higher temperatures hasn’t affected how Bartow maintains any of its system components, which is mostly focused on getting hardened to better withstand another way of life in Florida — hurricanes.
Hardening measures in Bartow have included undergrounding, enhanced pole inspections and treatment, installing trip savers, and improving tree trimming.
“A lot of the wind, by itself, generally our facilities could withstand that, but when it knocks down the trees is typically when the most damage is done,” he said.
When hurricanes and other storms hit, Poucher said the mutual aid network — particularly within the state — is critical in helping Florida communities to recover as quickly as possible, such as after tornadoes hit the Tallahassee area in the late spring.
The utility has updated its tree trimming to a three-year cycle and adopted more effective practices. Poucher noted that utilities across the state have been putting resources into various storm hardening measures, including installing wider poles set into bigger platforms, and improving conditions around critical facilities for about two decades. However, the wider poles and crossarms have supported another reliability threat in Bartow, which is nesting ospreys. In addition to building large nests on crossarms, they can often drop sticks while building the nests that end up in the lines. Poucher said that making the poles more “vertical,” or setting another, taller pole nearby can help them decide to build their nest elsewhere, avoiding such incidents.
Since getting hit with multiple hurricanes in 2004, Bartow instituted an 8-year cycle for inspecting and re-treating or replacing poles.
Bartow has also pushed for mandating undergrounding service lines for new developments, which has helped in getting about a quarter of Bartow’s service underground. Poucher estimated that the system could get to about 60% underground at some point, but that it is an expensive endeavor, especially when overhead service is already established.
One of the items that has helped the most in reducing sustained outages, said Poucher, is trip savers, which he said act like “mini reclosers” and help clear faults without causing power loss to customers. With about 100 such devices blanketing the system already, Poucher said Bartow has seen about a 30% reduction in sustained outages.
Adjusted Ratings
When asked to name a city in the U.S. that deals with heat, Phoenix, Arizona, likely comes to mind. Much of the Salt River Project’s service territory is in the Sonoran Desert, where over half of the days of the year see high temperatures above 86 degrees Fahrenheit. An analysis from the Washington Post estimates that by 2050, Phoenix will endure an estimated 126 days each year with heat that reduces transformers’ performance, or 19 more days of extreme heat than it currently experiences.
“Providing reliable and affordable power during extended periods of extreme heat is a foundational aspect of Salt River Project’s annual operations,” said representatives from the public power utility. “To ensure a reliable power grid year-round, our engineering design standards and electric system planning reflect the impact of high temperatures on our equipment and our load forecast.”
Recognizing that elevated temperatures may decrease the life of electrical equipment, SRP regularly reviews equipment standards to ensure it is using the appropriate sizing of electrical apparatus to account for high ambient temperatures. For example, while typical industry ratings of large power transformers expect 65 degrees Celsius over ambient temperature, SRP lowers this to 55 degrees for its ratings. SRP also tracks the performance, loading, and failure rates of its equipment, which allows it to replace heavily loaded equipment prior to failure.
SRP’s team closely watches the long-term load forecast and bases week-ahead planning on real-time weather information and predictions that can include the full range of high temperatures. SRP also recently revamped its long-term planning approach to an integrated system plan, instead of a long-term plan that solely focuses on power supply.
“Our Integrated System Plan is unique among utilities in that it takes a holistic approach to planning across generation, transmission, distribution and customer programs to develop a future power system that continues to responsibly deliver affordable, reliable and sustainable power,” said SRP.
The plan models multiple factors and scenarios, including worsening climate conditions, to better understand how its whole system could be affected, including customer programs, pricing, and system operations.
Climate conditions are only one of a handful of anticipated changes affecting SRP’s territory. SRP is seeing strong growth in electricity demand due to an increasing population, electrification, data center and industrial growth, and other factors. Through its ISP, SRP found it will need to at least double the number of power resources on its system in the next 10 years. It is preparing to add 7,000 megawatts of new renewable resources by 2035, including 6,000 MW of large-scale solar. SRP’s plans also include new fast-ramping natural gas units, which the utility said will allow for meeting its customers’ energy needs and better integrate the intermittent renewables, both pieces that it sees as critical to maintaining its industry-leading reliability.
“Adding this significant number of resources must happen at this pace to meet growing energy demand in the Phoenix metropolitan area and as SRP completes the planned retirement of 2,600 MW of coal resources,” added SRP.
