Sound Waves to Fight Wildfires: How Does it Work?

By Lisa Wirthman, Contributor
Photos by Noah Berger

Driving from Silicon Valley through California’s Sierra Foothills to Nevada City last November, there was an unavoidable smell in the air from the region’s wildfire devastation, remembers Suchinder Paul Dhillon. “It was something beyond charring and I had never smelled anything like that in my life,” he says. “It’s just something that sticks with you.”

Camp Fire Aftermath
Photographed by Noah Berger for Dell Technologies

It had been just one year since the 2018 Camp Fire burned more than 150,000 acres in nearby Butte County, becoming the deadliest and most destructive wildfire in California history. A news image of a car trying to evacuate the deadly blaze, surrounded by towers of flame, motivated Dhillon to take action and co-found Automation and Robotic Sciences and Artificial Cognizance (ARSAC) Technologies, a startup that’s building innovative systems to fight large wildfires, where he’s now the CEO.

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Across the globe, deadly wildfires from California to Australia are creating new risks for both humans and the planet. In California alone, the annual burn area jumped five-fold from 1972 to 2018 due to increases in the frequency and size of wildfires, according to a 2019 study by the American Geophysical Union.

“Fire season is getting longer and getting worse,” Dhillon says. “It’s no longer a question of whether a disaster happens. It’s a question of when it happens.”

Drowning Fire With Sound

Amid the growing devastation, technology offers a promising solution once deemed impossible: Extinguishing wildfires with sound waves. The breakthrough came in 2015, when two undergraduate engineering students, Seth Robertson and Viet Tran, created an acoustic fire extinguisher for their senior design project at George Mason University.

In 2015, two undergraduate engineering students, Seth Robertson and Viet Tran, created an acoustic fire extinguisher for their senior design project at George Mason University.

Initially created to put out small kitchen fires, the acoustic extinguisher quickly went viral. Today, the duo is consulting with ARSAC, which licensed their invention with the goal of scaling it to fight large wildfires.

Interest in ARSAC’s acoustic technology is global, says Dhillon, including queries from France when the Notre Dame Cathedral caught fire in 2019, and, more recently, from Australia as the country faced its worst wildfire season in decades.

“The massive recognition of this project has always been a nice perk, but the fact that we’re able to impact the world in a good way with our work and passion is the most rewarding thing,” says Tran. Both he and Robertson have since graduated and now work for private defense companies.

Finding the Right Frequency

The acoustic extinguisher works by using sound waves—a type of pressure wave—to push oxygen away from the source of a flame and spread it over a larger surface area. These actions break the fire combustion triangle made up of heat, fuel, and oxygen, the three elements required for a fire to burn. The acoustic fire extinguisher puts out flames using low frequency bass (30 to 60Hz) without relying on water or chemicals.

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Acoustic technologies were unsuccessfully tested as a firefighting tool by the United States Defense Advanced Research Projects Agency back in 2008. Undaunted by past failures, as well as skepticism from classmates and faculty, Robertson and Tran solved the problem by adding vortex rings, which move particles in circles around a center core, to carry sound waves over longer distances without losing mass or kinetic energy.

“There were many obstacles when we first came across this idea,” says Tran, and the challenges continue. Testing, for example, is costly, and there are no standardized tests for the technology, he notes.

ARSAC, which was started as a drone company in 2017, is now helping push acoustic technology to the next level. “Our mission is to take new and existing technologies that exist in very disparate ways within the current market and put them together in ways that can improve the quality of emergency services and disaster relief,” says Dhillon.

Solving a Global Problem

Over the past 50 years, there have been few technology advances in firefighting, explains Dhillon, a former volunteer firefighter. “One of our biggest hurdles now is that fire research is typically about 20 years behind any other kind of disaster research,” he adds. “We have to do a lot of it ourselves.”

Currently, ARSAC is creating an integrated system designed to specifically fight large wildfires that relies on arrays of acoustic extinguishers, sensing technologies, and an army of ISR (intelligence, surveillance, and reconnaissance) drones to detect and contain wildfires.

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While the product is still in development, the company is nearly ready to demo a force multiplier to extend the extinguisher’s range, and plans to reveal a pre-market prototype of the new integrated system in March 2020. At that point, the company hopes to test the system on the ground, likely in a controlled burn, Dhillon says.

Changing the Game

On a larger scale, ARSAC’s goal is not to completely extinguish wildfires—or replace firefighters—but to create acoustic boundary lines that prevent such fires from spreading. “We think we’re going to be able to buy those firefighters time, which is the real killer in a disaster situation,” Dhillon says.

ARSAC’s technology may prove particularly disruptive because it’s designed as a “sense and respond system,” he adds, rather than a “sense and react” system. The difference? ARSAC’s integrated fire protection system aims to not only detect embers but also track the location and direction of burgeoning fires to prevent them from crossing property lines.

ARSAC’s system employs sensors to detect a heat bloom and then send out spikes on a given frequency that can be used to track the fire’s flow, Dhillon explains. Drones can then be dispatched to provide aerial surveillance to monitor the fire, and arrays of sound-wave fire extinguishers along property lines can be pointed in the right direction to create an acoustic fire barrier.

“We want to be ready when the fire comes instead of waiting to react,” Dhillon says.

Building Community Partnerships

ARSAC’s primary customers are government agencies and private organizations that oversee large land areas like national parks, and therefore have a greater ability to address large wildfires than individual consumers.

Cities are also interested in the technology: Galvanized after the 2018 Camp Fire, Nevada City officials invited Dhillon, Robertson, and Tran to demo the technology for the local community last October. “We saw it as great opportunity to go and engage with people who are exposed to wildfires,” Dhillon says. Nevada City is also a potential partner for larger-scale testing of the technology, he adds.

In the Western U.S., and countless areas across the globe, wildfire devastation continues to increase, says Dhillon. “With those kinds of risks, it is a moral crime not to develop a system to address the issue,” he says. “We really just want to do the right thing.”