Sprayable Hydrogels for Preventing the Rekindling of Wildfires

Overview

Wildfires have been an increasing problem in California due to climate change. The recent Palisades fire was one of the most expensive on record, costing an estimated $250 billion dollars. The Palisades fire was caused when an earlier fire was extinguished above ground but still smoldered underground. 6 days later, strong winds pushed the fire above ground into vegetation and started the Palisades fire. Preventing rekindling requires a lot of time and effort to stop. The best firefighters can do is spray them with water before leaving to combat other parts of the fire. The first goal of this project was to find a hydrogel product capable of keeping forest fires from reigniting. We knew that hydrogel was capable of holding hundreds of times its weight in water and could release it over a long period of time. Our hypothesis was that potassium polyacrylate would be the best at preventing rekindling, because it can hold the most water. The second goal of this project was to design a sprayer capable of mixing the hydrogel into water as the water was spraying. We thought we could use the Venturi effect because it is used to mix a secondary material into water as it is being sprayed. The first test we did to identify the best hydrogel was to take 9 different hydrogels and test how well they retained water in an oven. We then took the most successful hydrogels and tested how well they stuck to a vertically hung leaf. We also tested how fast the hydrogels hydrated. We selected sodium polyacrylate as the best hydrogel. We next tested different ratios of hydrogel to water to see how well they could prevent rekindling. We used charcoal briquettes as a model for recently burned vegetation. We found that plain water performed the worst, with the coal reigniting almost immediately after application. The hydrogel mixtures performed better with 100% hydrogel performing the best. Once we had the best hydrogel, we designed and tested 8 different iterations of our hydrogel distributor. We used the Venturi effect and entrainment to suck hydrogel crystals into the water stream. The two biggest problems were the weak suction and nozzle clogging if too much hydrogel was added at once. Our final iteration used a combination of gravity and suction to bring the hydrogel into the nozzle and had a built in funnel to properly direct the hydrogel crystals. Our experiments demonstrated that hydrogel could be more successful at preventing rekindling than plain water. We created a method dispensing the optimal hydrogel and demonstrated it could disperse the hydrogel over a large distance. Our model was designed for a normal garden hose, but this design would work on any hose, including a fire hose. To adapt it, we would widen the rubber tube and make the Venturi nozzle out of a far more durable material, like steel. We would also increase the capacity of the hydrogel container. This device could be used for commercial use and homeowner use.

Competition history

• CSEF 2026 Environmental Engineering (Junior Division) · Entry J-11-04

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