New Fire Retardant Acts Like 'Vaccine' Against Wildfires

4 min
A utility pole, treated with long-lasting fire retardant fluids, avoids damage during a controlled burn. (Image courtesy of Jesse D. Acosta)

California’s last two fire seasons were brutal. As the Legislature struggles to fund fire safety proposals, and agencies spend more on firefighting crews, a team of scientists is proposing a novel solution: extinguishing fires before they start.

“This is something we do with vaccines all the time,” said Eric Appel, materials scientist at Stanford. “You have high-risk populations and you vaccinate them against the disease in the first place. As with many things, prevention is cheaper, easier and more effective than treatment.”

Appel is senior author on a recent study published in Proceedings of the National Academy of Sciences, reporting on the first field trials of a long-acting, environmentally benign fire retardant that he hopes will reshape the way fires are prevented and fought in California.

"Most people think that fires just sort of start willy nilly anywhere in the forest. But it turns out that that's not really true."

The study found that most wildfires start in the same locations, and that the retardant will protect an area for months.

"So what that means," Appel says, "is that you would only need to treat a very small amount of land in order to prevent a majority of fires."

The Spark of An Idea

For co-author Jesse Acosta, adjunct professor of Natural Resource Management at Cal Poly San Luis Obispo, a moment of inspiration came years ago, as he stood in the sweltering heat of Hawaii, working for the U.S. Forest Service in a Smokey Bear costume, trying to convince people to care about fire prevention.

"I don't know if it was the actual discomfort of the suit that made me think about things differently, or if it was some sort of late-night epiphany," said the former Fire Prevention Forester, "but it became very clear to me very quickly that [outreach] was not effective in terms of preventing fires.”

Likely, it was both, but it would take a move to Connecticut and a chance meeting with a colleague for the building blocks of a new approach to fall into place.

At the time, Eric Appel, now a materials scientist at Stanford University, was studying medical drug delivery at MIT, "answering the question of 'How do we keep these drug molecules stable and get them where they need to go and keep them where they need to be?'"

The answer lead to the development of a "hydrogel" made of inexpensive, renewable and benign materials that could deliver medications in a human body and keep them stable over time. For example, an early application allowed people with diabetes to receive a single injection that supplied insulin over six months.

Hydrogels themselves may seem an unlikely hero: They're pale, shapeless blobs reminiscent of thick shampoo or mayonnaise. You mix them up in buckets, foregoing a lab coat for rubber boots. But to Appel, their beauty lies in the thoughtfulness of their design.

"The gels we’re making are sophisticated and scalable. They form from simple components," said Appel. "And they function like molecular Velcro," meaning they can change their properties to allow them to be sprayed easily from a needle or nozzle.

Acosta was aware of Appel's hydrogels and thought about what might happen if you replaced medications with a "molecular cargo" of flame retardants.

“It was around midnight when it finally dawned on me to use these hydrogels," Acosta said, pointing out the many commonalities shared between what makes something safe for the human body and what makes something environmentally benign. "Let’s wrap up fire retardant in these hydrogels and see if they are able to stick to fuels and persist through weather.”

Out of the Lab and Into the Fire

After this unlikely series of events, Appel, Acosta and collaborators received funding through Stanford's Realizing Environmental Innovation Program.

Appel and his collaborators began working with Cal Fire to identify where fires start each year. They found fires reproducibly start year-after-year in the same places, calculating that 84 percent of wildfires in California in the last 10 years have started at the same high-risk roadside spots or near utilities infrastructure.

Following the success of a pilot study on small piles of pine shavings, this new study tests hydrogel performance on a larger scale. 

They treated plots of native grass 10 feet long and 10 feet wide with their product and set both those and untreated control plots alight, watching how they burned. 

"They just explode," Appel said of the control plots. "It’s a pyromaniac’s best afternoon.”

Appel and Acosta also wanted to address a major shortcoming of current retardants — that they are not meant to persist long beyond their initial application.

In fact, much of the millions of tons of retardant that planes drop onto fires each year are rendered useless by subsequent dumps of water onto active fire-lines. Even heavy dews and fogs, common along the California coast, can decrease the retardants' efficiency.

The hydrogel, by contrast, stays at full potency and continues delivering fire protection over months of the traditional fire season. The hydrogels also stand up to dew, fog, and moderate rain, although they are intentionally designed to wash away at the start of the wetter fall months.

“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,” said study lead author Anthony Yu, a Ph.D. student in materials science and engineering at Stanford, in a media release.

The New Reality of Fire in California

According to Acosta, a policy of suppression and a cultural view that fire is villainous has pitted the country against a future where extreme fires are guaranteed. This is due to a massive buildup of fuel — dead trees, brush and chaparral — in an ecosystem that has historically required fires as a natural part of the landscape.

"Every fire we fight, every fire that happens, has the potential to be the Mendocino Complex or the Thomas Fire or the Carr Fire or the Ferguson Fire."

And the economic costs of fighting fires have become enormous. Last year the federal government spent $3 billion to put out blazes. Local agencies are also strapped. Fighting fires and defending one hot, 4-mile stretch along Highway 118 in Ventura County costs an average of $5.5 million annually.

The true importance of hydrogels, Acosta says, extends beyond their use as a long-term, environmentally benign treatment. By stopping fires from ever starting, it pushes the balance of power further into our favor.

"We can stop fighting these catastrophic fires in June and July, Acosta said, "and fight them on our terms with prescribed burns in cooler, wetter weather and during times when we have more money freed up for fighting fires."

In the next week, crews will apply the long-term fire retardant to some of Highway 118 and two other stretches of road in San Diego County. These will be the first large projects of a company formed to promote the retardant, which is now sold as Fortify. Appel and Yu are listed as inventors on the Fortify patent. Appel is Chief Technical Advisor for the new company, Ladera Tech. Jesse Acosta is Chief Business Officer.

Wes Bolsen, president and CEO of Ladera, estimates roadside treatments will cost Cal Fire and the California Department of Transportation between $20,000 and $200,000, depending on the mileage and other factors.

Bolsen says utilities have also expressed interest in the retardant.

Projects such as this may signal the first drop in a flood of new tools and methods aimed at developing a more holistic approach to accommodating fires in the state. Acosta feels hopeful because ultimately everyone he has worked with — from politicians to firefighters to loggers — are working toward a common goal.

“These new technological advances," he said, "are giving us the power to make new and better decisions."

One example of this is that Appel and Yu hope that their retardant won’t just help put out fires. The researchers hope products like this will help start controlled burns. Not only can it be used as a tool to limit the area burned, it can protect rare plants within it.

“If they're out in an area, you can't just burn through because you might damage those plants,” said Appel. “So these materials can actually be used to provide sort of a protective layer around those plants.”

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