Alexandre Moreira is a research scientist at the Lawrence Berkeley National Laboratory.
Adverse wildfire-prone conditions might become more frequent due to climate change, potentially increasing the incidence of extreme fire events. But this can be prevented by properly optimizing investments and operational decisions for power grids while explicitly considering the relationship between power lines and wildfire ignition under a methodology being developed by researchers at the Lawrence Berkeley National Laboratory with support from the Department of Energy’s Office of Electricity Advanced Grid Modeling program and in partnership with professors from the University of Michigan and the University of Washington.
The proposed methodology is capable of balancing the costs and benefits of different wildfire mitigation approaches and indicating the optimal portfolio of investments to protect power grids.
In this century, wildfires quickly became one of the most feared extreme weather events and a major challenge to safely operating power grids in different locations within the U.S. and abroad. Wildfire-related damages to transmission and distribution assets exceeded $700 million between 2000 and 2016 in California, which is also where the frequency of small wildfires and the total area burned by large ones have significantly increased over the last two decades.
During windy weather periods with low humidity and high temperatures, power lines passing through areas surrounded by vegetation cause some of the most severe wildfires. In fact, if these areas are large enough, multiple ignitions might occur. Some examples of wildfires triggered by power lines include:
- The “Black Saturday fire,” which destroyed more than 400,000 hectares and caused 173 human deaths in Victoria, Australia, in 2009;
- The “Bastrop fire,” which resulted in the death of two people and the loss of hundreds of homes, in Texas in 2011;
- The “Camp Fire,” which led to the death of 85 people in 2018 and is the deadliest wildfire in the history of California; and
- The “Dixie fire,” which burned an area larger than 300,000 hectares in California in 2021.
Indeed, in California, out of the 20 most destructive wildfires observed in the past two decades, at least nine were caused by the interaction between electrical infrastructure and the environment.
Wildfires induced by power systems can be started mostly either when external objects, such as tree branches, come in contact with a power line or when the line itself comes in contact with nearby vegetation, equipment or other lines as depicted in Fig. 1. In either case, usually a line fault is followed by the ignition of nearby vegetation. The ignition process occurs when the power flowing in the conductor finds an alternative path to the ground, closing a circuit. This action can directly start a fire when close to vegetation by creating an arc, or indirectly through molten metal particles, burning embers or burning fluids.
In this context, the higher the power flow, the higher the thermal stress of the lines, and the higher the chance of electric arcs to occur. The duration and intensity of these arcs are directly related to ignition probability.
An example of a wildfire started by power systems
Permission granted by Lawrence Berkeley National Laboratory
An example of a wildfire started by power systems
Permission granted by Lawrence Berkeley National Laboratory
The missing puzzle piece to deal with this critical problem is determining how the benefits of different investment options should be balanced to mitigate wildfires and find the most cost-effective portfolio of actions.
Concerned about the numerous adverse fire incidents over the past two decades, electric utilities in California and elsewhere have started specific programs to tackle this issue. San Diego Gas & Electric has created numerous initiatives, including enhanced situational awareness, forecasting and wildfire risk modeling programs. Furthermore, infrastructure improvements have also been implemented, encompassing conductor covering, equipment modernization, protection enhancement and microgrid development.
Southern California Edison also developed special operational protocols and implemented vegetation clearance and conductor hardening. In addition, artificial intelligence and machine learning algorithms have helped the company to identify equipment defects via aerial inspections. Similar actions have been taken by Pacific Gas and Electric. The company is one of the utilities in California that use the Public Safety Power Shutoff program, where under specific weather conditions, power lines are actively de-energized in high-threat areas to prevent wildfire disruption. As a consequence, this program can cause power outages for customers during long periods.
A more recent initiative from PG&E, the so-called Enhanced Powerline Safety Settings, or EPSS, program, is helping to reduce the frequency of PSPS events by deploying protection devices that can rapidly de-energize power lines once in contact with external objects, therefore decreasing the amount of energy released by a potential arc and thus reducing potential sources of wildfire ignition. However, EPSS might increase the frequency of service interruptions compared to usual protection mechanisms as it makes protection equipment much more sensitive and potentially disconnects power lines even when it is not needed. In any case, there is no single silver bullet for the wildfires problem and a combination of different measures is needed to address this issue.
The methodology being developed by LBNL, in partnership with the University of Michigan and the University of Washington, can help system planners and operators to explicitly consider how power flow levels through power lines can increase ignition probability within high-threat areas. Essentially, the developed methodology considers different investment alternatives — for example, line coating, line undergrounding, installation of line segments through alternative paths paired with strategic placement of switching devices, etc. — and provides the portfolio of actions that will increase the flexibility of the system to deal with wildfire-prone weather conditions and minimize service disruptions.
By properly considering how the magnitude of power flows through lines can increase fire ignition probability, the methodology is able to identify tactical investments that can decrease frequency and duration of interruptions and would not be properly valued otherwise. This is one of the main advantages of the LBNL-UM-UW methodology compared with current mitigation efforts together with the capability of considering multiple intervention options.
The methodology is under active development and has been presented to SDG&E, whose territory is partially affected by wildfires. Improvements to enhance its computational efficiency of the developed approach are currently the main focus of the project.
