Crews are still scrambling to bring back power to the 219 transmission lines knocked out by Hurricane Laura in Louisiana last week, leaving 110,000 households still without power on Sept. 4. The effort requires a full-scale reconstruction, and the sheer logistics of rebuilding each line includes many moving parts.
“This is not a restoration. It’s almost a complete rebuild of our transmission and distribution system that serves Calcasieu and Cameron parishes,” Phillip May, Entergy Louisiana president and CEO said in a statement this week.
Nearly two-thirds of the downed transmission lines are in Southwest Louisiana. The storm also damaged about 1,000 of the transmission structures that support the lines. Laura made landfall just south of Lake Charles in Cameron Parish Aug. 27 as a Category 4 storm packing 150 mph winds. Entergy says it expects to restart power for the first of its nine transmission lines into Lake Charles in two weeks.
Entergy’s system-wide damage includes 292 substations. Damage to the distribution system involves 9,760 poles, 3,729 transformers and 18,707 spans of wire. The utility serves Louisiana, Texas, Arkansas and Mississippi.
“To rebuild infrastructure like that, each one of those structures is a capital project,” says Scott Aaronson, vice president for security and preparedness for Edison Electric Institute, the association representing all 20 U.S. electric companies.
Some Damage Beyond Repair
If transmission lines are comparable to interstates, then substations would be the equivalent of off-ramps, and distribution lines are the streets and roads to homes and businesses. That’s important to note because the extent of damage to key components of the grid is so great that many repairs will require an infrastructure-replacement approach.
All nine transmission lines that deliver power to the Lake Charles area were knocked out of service. A significant number of the transmission structures that support the lines were damaged beyond repair and will require complete replacement—a far more complex process than replacing distribution poles and wires.
Obtaining the parts and pieces to reassemble the transmission structures will be a massive undertaking in and of itself. Companies keep a supply of cross-arms and other distribution system components available in case of routine outages, but that’s not as easy to do with transmission components.
“Very rarely do companies have a large stock of transmission infrastructure just waiting to be used,” Aaronson says.
Unlike distribution system components that can be mass produced, transmission structures are unique to the lines they serve. Each transmission line is different and requires customized components to accommodate the terrain, topography and voltage class.
“Each structure has to be engineered and custom manufactured to ensure that we’ve got the right characteristics of the structure to support the line itself,” says Michelle Bourg, vice president of transmission asset management for Entergy.
Each 500 kV transmission tower weighs about 20 tons, and it takes three tractor-trailers to transport. The first line Entergy is working to restore has 11 structures that were destroyed. “One by one, we’re moving the structures down from the warehouse in Little Rock, to the worksite around Lake Charles,” Bourg explains, adding that this doesn’t include other materials required.
Skilled workforce availability is another concern, because each transmission structure takes about 1,300 hours to reconstruct, Aaronson says.
Utilities from across the country usually offer mutual assistance to restore power on the distribution level after a disaster. “There are not as many of those humans on the transmission side of things,” Aaronson says. Adding to the challenge is that many of these structures are located in marshes, bayous and other areas that are not easily accessible.
“Because of the importance of those transmission lines, we’ve got thousands of people dedicated to rebuilding this system in short order, and not in the most ideal of circumstances,” Aaronson says.
The utility’s next priority will be rebuilding the transmission facilities required to restart Lake Charles-area power generation, including the Calcasieu Plant and Lake Charles Power Station. Those sources deliver power to critical services, including hospitals, other utilities and public safety venues.
Typical restoration protocols call for rebuilding the transmission structures first, powering up the grid and then building out the distribution system. But with the transmission system in need of a full rebuild, Entergy has been looking into alternative sources like industrial portable generators that can power some of the larger electricity-generating facilities in the interim.
“In this case, we may have generation starting first, and then building out with the transmission to get to customers,” Bourg says.
Much like the development of a COVID-19 vaccine, the effort to rebuild the heavily damaged power grid serving Louisiana and Texas will require an all-hands-on-deck effort of the utility sector and its critical infrastructure contractors. Entergy has been working with its partners across the industry to source anything they can to rebuild some of the major structures, Aaronson says.
“It’s taking the wisdom and expertise of an entire sector—or in our case, the electrical-engineering world—and focusing it on one really big problem, all under duress,” he adds.
Burns & McDonnell has been mobilizing its teams. “For utilities in the region, Burns & McDonnell is deploying engineers and construction resources to first assess the prospective damage at multiple power plants and power transmission lines in the area, provide reporting to the responsible parties, and identify the contractual and logistics path forward to coordinate and manage the activities to return the plants and facilities to normal operation,” says Jeff Allen, the firm’s vice president and construction design-build group regional manager in Houston.
Reconstruction of the region’s power grid could present an opportunity to address resiliency in future storms. After Hurricane Sandy, for example, New York-based utility Con Edison Inc. invested $1 billion in fortification measures such as raising critical equipment, burying overhead lines and installing flood barriers and submersible equipment.
Although Aaronson says Louisiana’s utilities are still in emergency mode, storm-hardening measures could come up in later conversations. “At some point, we’ll turn a corner and be able to talk about building back better and more resilient for the future,” he says. “More to come on that.”