Here’s where California’s power grid is most at risk for high winds and fire threat

Wildfires swept by intense winds like those on Maui last week are something Californians have become very familiar with.

Here’s how the state is trying to prevent more destruction:

After years of study and debate, electrical utilities are shutting off power to high-risk areas across California during high heat and wind events. The Public Safety Power Shutoffs are being implemented but there is concern for the few who rely on electricity to survive around the clock. Some areas of the state have power outages longer and more frequently than many others.

While wildfires can be started by a broad variety of causes (lightning, arson, smoking, etc.), electrical power lines were shown to be on the rise as an ignition source. Historically, electric utility infrastructure has been responsible for less than 10% of reported wildfires.

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However, wildfires attributed to electrical infrastructure consist of roughly half of the most destructive wildfires in California history, including the 2018 Camp Fire, which destroyed 18,804 structures and claimed 85 lives.

Wind, the grid and fire threat map

This map was made by Xinyue Wang and Paolo Bocchini of the Department of Civil and Environmental Engineering, Catastrophe Modeling Center, ATLSS Engineering Research Center at Lehigh University. It shows where power line ignition under high winds is a higher threat.

Transmission conductors bear the greatest exposure to wind hazard events, as they span long distances across variable terrains. Vegetation contact was the primary cause of power utility ignition in California, with a contribution of 53.5%. Under high wind conditions, conductor-vegetation contact generally occurs in two forms: broken trees/limbs falling on the conductor and the conductor swinging out to nearby vegetation.

You can read more about the map and methodology here.

Everyone knows it’s windy

Intense winds are called several names such as foehn winds, Diablo winds or Santa Ana winds. You can find the Santa Ana Wind Fire Threat Index for Southern California here.

The map below is the California Public Utilities Commission’s Fire Threat index for 2021. It shows where fuel and terrain create the most risk across the state.

You can find high-resolution images of the CPUC map here.

Shutting the power off

The maps below are from PSE Healthy Energy, a nonprofit research institute that studies the way energy production and use impact public heath. These maps show the areas of California that have had no Public Safety Power Shutoff outages and the highest average annual frequency of Public Safety Power Shutoff outages as well as what areas had the longest duration outages. Not all areas report.

You can zoom in to the maps at PSE Healthy Energy here. You can find outage maps for several California power companies here.

Gone in 90 minutes