Managing the risk of wildfires

In the August 25, 2019, issue of the The Washington Post, Steven Pearlstein wrote a column about how San Diego Gas & Electric (SDG&E) is pro-actively managing the risk that their power grid will cause a wildfire.  Some wildfires are caused when trees or branches fall and hit a transmission line and then the energized power line sparks a fire on the ground.  The power company's approach addresses two potential problems: damage to the transmission line, and the transmission line sparking a wildfire.

For the first risk, SDG&E is burying transmission lines in high-risk areas in the mountains and backcountry.  This is a preventive action because buried transmission lines can not be damaged by falling trees and branches.

For the second risk, SDG&E has installed a system that monitors transmission lines in remote areas, detects when a transmission line is damaged, and turns off the power to that transmission line instantly.  This contingency plan (turn off the power if the line is damaged) prevents the lines from sparking a wildfire.

Moreover, SDG&E is monitoring the conditions in the high-risk area and calculating the conditional probability that a spark would lead to a large wildfire in those locations.  If that conditional probability becomes too high, then the risk has increased to an unacceptable level, and the power company cuts the power to that transmission line (even though it is not damaged).  From Pearlstein's column:

“We are doing with wildfires what the National Weather Service has done with hurricanes,” said Scott Drury, the utility’s president. ... The wildfire model gives SDG&E the confidence to shut off power because it can pinpoint precisely where and when the risks are at levels that have resulted in disastrous fires in the past.

Pearlstein's article also discusses how people in the area are managing the risks associated with a power outage: parking outside their garages, storing water, and buying generators.