Gel Could Help Prevent Wildfires In High-Risk Areas

Oct 1, 2019

Wildland firefighters use fire retardant — the red stuff that air tankers drop — to suppress existing blazes. But Stanford researchers have developed a gel-like fluid they say makes fire retardant last longer and could prevent wildfires from igniting in the first place if applied to ignition-prone areas.

“Right now we’re sort of limited by the tools at hand and we wait for fires to start and then we go out and try to put them out,” said Stanford materials scientist Eric Appel.

He says the gel potentially offers a more proactive approach. It could allow them to apply flame retardant in areas that commonly tend to ignite, like along certain roadways or on utility poles, like the ones that caught fire in Paradise, California, and blocked escape routes when they fell. 

"You can treat a small amount of land and prevent a very large proportion of the fires that occur," he said.

Usually, wind and rain get rid of retardant quickly, but as Appel and his colleagues wrote in a study published Monday in the journal Proceedings of the National Academy of Sciences, this gel is designed to keep the retardant around for a whole wildfire season before being washed away by heavy rain.

The researchers burned 220-pound piles of greasewood. This image, taken one minute after ignition, shows treated piles burned more slowly than untreated piles, even after four weeks of exposure to the elements and a simulated half-inch rainfall.
Credit Jesse D. Acosta

In addition to lab experiments, the researchers also tested the product outdoors. They sprayed plots of open grass and piles of greasewood with the gel-retardant mixture, then let them sit for two weeks, then poured water on them to simulate a half-inch rainfall before letting them dry out for another two weeks. Finally, they set them on fire. In one minute, more than 90% of the untreated grass areas burned, while fires in the treated grass plots were limited to a small area and appeared to peter out. Untreated greasewood piles ignited quickly and took less than two minutes to reach a steady-state burn temperature, while treated ones ignited more slowly and took more than six minutes.

The study’s lead author, Anthony Yu, a PhD student in materials science and engineering at Stanford, said in a press release the method should be more affordable than fighting fires once they get out of control: “You can put 20,000 gallons of this on an area for prevention, or 1 million gallons of the traditional formulation after a fire starts.”

Crystal Kolden, a wildland fire expert at the University of Idaho who was not involved in the study, emphasizes that the gel isn’t intended to be applied across vast landscapes.

“What it will do is improve protection of critical areas, particularly homes and critical infrastructure, where small-scale application can support point protection and prevent disasters,” Kolden said. “It is a complement to the wide array of fire mitigation tools we have, not a silver bullet replacement.”

The study, "Wildfire prevention through prophylactic treatment of high-risk landscapes using viscoelastic retardant fluids," was published under CC BY-NC-ND 4.0 license. A version is embedded below. Tap the yellow arrows to see comments from people who were not involved in the research. 

This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Boise State Public Radio in Idaho, KUER in Salt Lake City, KUNR in Nevada and KRCC and KUNC in Colorado.