6 transmission resiliency strategies to combat extreme weather events

Extreme weather events are becoming more frequent, resulting in deepened damage to electric infrastructure and escalation of losses in lives and property. Electrical outages from these disasters have increased from an average of 50 per year in the early 2000s to more than 100 annually on average over the last five years. These events cause substantial economic losses through infrastructure damage, manufacturing and labor disruptions, and property value losses. 

On average, there was a billion-dollar disaster every four months in the 1980s. This has increased to a current average of one every three weeks. Between 2018 and 2022, the U.S. witnessed 89 such events, costing an approximate $150 billion each year. 

In this era of intensifying disaster events, the need to bolster our transmission infrastructure has become more critical than ever. A review of recent past events further highlights the fragility of the electric infrastructure and stresses the importance and need for improved resilience strategies. 

Hurricanes Laura (2020) and Ida (2021) and Hurricane Laura in 2020 caused severe power outages from damaged transmission infrastructures. Hurricanes Irma and Maria (2017) revealed Puerto Rico’s grid fragility, resulting in severe economic losses. 

California’s Camp and Dixie Fires (2017-2021) damaged transmission lines and prompted public safety power shutoffs. On the other end of the weather spectrum, Winter Storm Uri (2021) devastated the Texas grid, collapsing power lines and towers.  

These recent weather events underscore the critical need for enhanced proactive transmission resilience strategies, emphasizing the necessity for thorough planning and collaboration among utilities, grid operators, and government agencies to effectively tackle the challenges posed by extreme weather conditions.

Strategies for utilities to improve electric grid resiliency 

In response to the increasing severity and regularity of extreme weather events, electric utilities must urgently pivot toward a proactive stance, drawing lessons from these past disasters to bolster the resilience of the future transmission grid. 

To fortify the grid and mitigate the future impact, electric transmission utilities must consider six key strategies: 

1. Grid hardening and infrastructure investment

Building more transmission infrastructure to add some redundancy or retrofitting existing infrastructure to withstand more frequent and extreme weather conditions are essential steps. Redundancy should be considered by adding or configuring multiple paths to transmit electricity where possible—where it’s cost-effective and there are no right-of-way or land use issues of significant concern. Examples of retrofitting or enhancements could include insulating transmission lines to prevent fire risk, employing high-temperature low-sag (HTLS) conductors in design, replacing poles with steel, fiberglass, or reinforced concrete to withstand high winds, and investing in underground transmission systems in vulnerable areas. Technological advancements are decreasing the cost of undergrounding, making underground transmission lines viable options for utilities. 

PG&E, for example, is taking on the largest effort in the country to underground 10,000 miles of transmission lines in high-fire risk areas as part of its Community Wildfire Safety Program, aimed at reducing the risk of starting wildfires and limiting PSPS for customers during windy conditions.  

2. Dynamic line optimization (DLO)

Unlike traditional static methods, DLO considers real-time data about line conditions—such as weather, temperature, and energy load—to enable operators to dynamically optimize the capacity of transmission lines. This allows operators to safely increase power flow under favorable conditions, thereby enhancing efficiency and grid reliability.  

One notable example is the Belgian electric grid operator Elia, which has shown a 5-20% increase in line ratings that improve market dispatch cost-effectiveness and aids in the integration of and reduction in curtailment of solar and wind power. Texas utility Oncor and the New York Power Authority found that the average real-time transmission capacity was at least 30% greater than static ratings—thereby significantly reducing transmission grid congestion costs. 

3. Integrated vegetation management

Vegetation in proximity to transmission lines can lead to power outages, electrical faults, or even wildfires—especially during adverse weather conditions. Distribution utilities and transmission owners and operators can identify and selectively remove high-risk vegetation that pose a significant wildfire hazard and clearance risk. 

Advancements in vegetation management technology such as light detection and ranging (LiDAR) and drones equipped with sensors to monitor vegetation growth are technologies that can help improve targeted vegetation management. Additionally, integrated vegetation management (IVM) is a holistic approach that combines multiple vegetation management techniques while considering ecological, environmental, and regulatory factors. This approach provides a comprehensive proactive strategy for maintaining vegetation around power lines and balancing wildfire prevention with ecological conservation. 

4. Strategic aerial condition assessments

Leverage the systematic use of drones or unmanned aerial systems (UAS) to collect data and imagery for evaluating the condition and quality of utility infrastructure. This approach enables utilities to perform detailed inspections from the air, offering a comprehensive view that is often safer, more efficient, and less intrusive than traditional ground-based inspections. UAS are typically equipped with high-resolution cameras that conduct visual inspections of power lines, transmission towers, and other components of the electric grid. This allows operators to identify issues such as damaged equipment, loose connections, or vegetation encroachment that may pose a risk to the infrastructure. Infrared sensors can detect variations in temperature along power lines and substation components identifying hotspots or potential equipment failures before they lead to outages. 
 
Emergent technology, such as LiDAR and specialized sensors provide the ability to create detailed 3D maps and proactively detect obstacles and assess structural integrity. UAS are particularly valuable for inspecting electric grid infrastructure in remote or challenging-to-reach areas such as mountainous regions, dense forests, or areas with difficult terrain. This capability is far superior to that of traditional approaches to more accurately identify and mitigate issues while proactively improving grid resilience. 

5. Microgrids and Distributed Energy Resource (DER) integration

Utilities can develop microgrids in critical or remote areas to provide localized power generation and distribution during outages or to replace ageing, at-risk transmission infrastructure. As PSPS events are a common mitigation in wildfire prone areas, adding microgrids to those areas can enhance reliability by ensuring customers remain energized. Studies have shown that decreases in the cost of solar plus battery storage systems can enable an opportunity to replace aging transmission infrastructure with microgrids in remote areas. As part of its Wildfire Mitigation Plan, PG&E deployed renewable remote grids as an alternative to having overhead distribution lines through areas with wildfire risk and has future plans to expand the use of such systems.  

6. Emergency preparation and response methods

Develop proactive and intelligent emergency response plans to prioritize and coordinate critical repairs efficiently before and after a disaster. To highlight, two established methods are PSPS and Emergency Restoration Systems (ERS).  

Proactively, multiple western US utilities employ PSPS programs, whereas during high-risk weather conditions, utilities proactively turn-off selected transmission lines to reduce the risk of a wildfire. PSPS programs are prevalent in wildfire plagued California and in the aftermath of the August 2023 wildfires, Hawaiian Electric has begun discussions with government, emergency response, and community stakeholders to determine how a PSPS program can be designed and implemented.  

Utilization of ERS or modular restoration structure components is a unique method to combatting the collapse of transmission towers after a disaster event. ERS are temporary, modular tower structures made of aluminum alloy or hot-dip galvanized steel. ERS are quick-erect towers that can be raised in the field in less than a day and can address power outages or tripping in power lines during emergencies, meet maintenance requirements, and divert circuits when needed. 

Conclusion 

As natural disasters intensify in both frequency and severity, electric utilities and transmission companies must take proactive steps to improve transmission resiliency. By learning from past experiences, investing in infrastructure and technology, and fostering collaboration with stakeholders, the industry can better prepare for and respond to the challenges posed by an evolving climate and an increasingly unpredictable environment.  

The lessons learned from previous disaster events and outages across the U.S. accentuate the importance for a comprehensive and proactive approach to electric grid resiliency. By implementing the strategies outlined, transmission infrastructure can be strengthened to ensure that it remains reliable in the face of the growing threat of natural disasters.