Wetting agent douses underground "zombie" fires with great efficiency
Raging fires are generally bad news, but smoldering peat fires can do more environmental damage and present unique challenges for those trying to extinguish them. Researchers in the UK have come up with a new formula for tackling these so-called "zombie fires", which can burn through carbon-rich organic matter underground and trigger flaming wildfires again once the danger appears to have passed.
In addition to being very difficult to put out, zombie fires are particularly destructive because they burn through soil that is rich in organic matter like peat, releasing massive amounts of carbon emissions in the process. Peatland fires pump millions of tons of carbon into the atmosphere each year, and require billions of liters of water each year globally to put out – in 2008 the Evans Road peat fire that burned for over seven months in the US consumed 7.5 billion liters of water to fully extinguish.
Part of the reason stems from the surface tension of water when used alone, resulting in a few large channels rather than the water running evenly through the soil, leaving smoldering hotspots. Scientists at Imperial College London have been investigating additives that might negate this problem, and have landed on what they believe to be a winning recipe for putting out smoldering peat fires in a fraction of the time with less water.
The team experimented with adding a biodegradable wetting agent made from plant matter to water in different concentrations, and then observing how that impacted controlled peat fires in a laboratory setting. This included concentrations of five and one percent, along with the use of pure water, with the team finding that the suppressant lowered the surface tension of the liquid, which enabled it to seep into the soil in a more uniform way and made it less likely to form large channels.
The one percent concentration reduced the average time it took to suppress the fire by 39 percent, while the higher five percent concentration reduced it by 26 percent. The scientists found that the agent encapsulates the fire and lowers its temperature, meaning the fire could be suppressed using between a third and a half of the usual amount of water.
“Fighting peat fires uses an incredible amount of work, time and water, and this biodegradable wetting agent could help everybody: fire brigades, communities and the planet," says senior author Professor Guillermo Rein. "This magical suppressant could make it easier to put zombie fires to rest for good.”
The team is now looking to build on these promising findings by conducting further experiments on controlled peat fires out in the field.
The research was published in the International Journal of Wildland Fire.
Source: Imperial College London