Inaudible Sound for Wildfire Defense: A New Frontier

A Novel Approach to Fire Suppression: Sonic Fire Tech

Approximately ten years ago, a pair of university students engineered a fire extinguisher capable of extinguishing flames utilizing only a powerful 10-inch subwoofer. This innovation quickly gained traction online, culminating in a demonstration featured on “The Tonight Show” with Jimmy Fallon.

However, following this initial burst of publicity, discussion surrounding the technology largely subsided.

This lack of continued development wasn’t due to a lack of effort. The initial demonstration by the students wasn’t the first proof of concept; the Defense Advanced Research Projects Agency (DARPA) began investigating the possibility as early as 2012. A review of academic publications reveals numerous researchers exploring this very idea.

Sonic Fire Tech: A Breakthrough in Acoustic Fire Suppression

Now, one startup asserts they have overcome the challenges associated with this technology. Sonic Fire Tech has developed an acoustic fire suppression system designed not only to extinguish existing fires but also to potentially safeguard homes and structures from the threat of wildfires. The company has successfully secured $3.5 million in seed funding from investors, including Khosla Ventures and Third Sphere, as exclusively reported by TechCrunch.

The economic impact of wildfires in the United States can reach as high as $424 billion annually. The severity of the problem, particularly in regions like California, has led to insurance companies declining to renew policies in areas repeatedly devastated by blazes.

Sonic Fire Tech has dedicated several years to refining its technology. Michael Thomas, chairman of the startup’s board, initially explored the potential of sound for fire suppression. When encountering obstacles, he contacted Geoff Bruder via LinkedIn. Bruder’s expertise, gained through his work at NASA, centered on heat and acoustics.

“This represents a rather unconventional founding story,” Bruder, the startup’s CEO and CTO, explained to TechCrunch.

Intrigued by Thomas’s concept, Bruder embarked on building a prototype. “I acquired a subwoofer and components from Home Depot and AutoZone, aiming to determine if we could surpass previous attempts,” Bruder recounted. “We successfully extinguished a fire from a distance of seven feet in my driveway.”

From Subwoofers to Infrasound

The startup quickly moved away from using a standard subwoofer, opting for lower frequency sound waves. Bruder explained that systems utilizing audible frequencies, powerful enough to suppress a fire, would pose a risk of hearing damage. “Essentially, a speaker design would need to be completely discarded and a new approach initiated,” he stated.

While the precise mechanisms by which acoustic energy disrupts combustion are still debated, the successful demonstrations by Sonic Fire Tech suggest a promising path forward.

The current system employs a reciprocating piston, similar to those found in automobile engines, but significantly larger in scale. An electric motor drives a crankshaft, which in turn generates pulses of infrasound – sound frequencies below the range of human hearing, typically around 20 Hz.

“Because we engineered every component ourselves, we were able to lower the frequency to a level below audibility, enhancing transmission range and ensuring safety,” Bruder clarified.

System Capabilities and Future Applications

Sonic Fire Tech’s current system boasts an effective range of 25 feet. The company anticipates that a larger system could operate effectively at distances up to 330 feet. They plan to offer system sales and installation at approximately 2% of a home’s value, and are currently in discussions with insurance providers to certify the technology.

To protect a residence, Sonic Fire Tech directs infrasound from a single generator through rigid ducts positioned along the roof’s ridge and under the eaves. The ducts positioned on the ridge target potential fires in gutters, while those under the eaves focus on suppressing flames near the walls. The system is activated by sensors that detect the presence of a flame.

A residential system consumes approximately 500 watts of electricity. For backup power during outages, Sonic Fire Tech is developing plans to utilize lead-acid batteries.

Unlike traditional sprinkler systems, this technology does not rely on a water source, a critical advantage in wildfire-prone areas where water may be scarce.

The startup is collaborating with PG&E and Southern California Edison to demonstrate the technology on their infrastructure. They have also signed a letter of intent with a chemical storage facility.

“The logical next step is to achieve certification as a sprinkler system replacement, allowing for easy installation in homes to protect kitchens and other vulnerable areas,” Bruder concluded.

Correction: Sonic Fire Tech is currently deploying its fire suppression system on the equipment of PG&E and Southern California Edison, not directly on residential homes.