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From: ScienceDaily (1:317/3)
To: All
Date: Fri, 12.03.21 22:30
'Magical' fire suppressant kills zombie
'Magical' fire suppressant kills zombie fires 40% faster than water

March 12, 2021
Imperial College London
New research shows a fire suppressant, when combined with water,
cuts the amount of time and water needed to extinguish peat fires
by 40%.

The researchers say this is a big step in tackling smouldering peat
fires, which are the largest fires on Earth. They ignite very easily, are
notoriously difficult to put out, and release up to 100 times more carbon
into the atmosphere than flaming fires, contributing to climate change.

The fires, known as 'zombie fires' for their ability to hide and smoulder
underground and then reanimate as new flames days or weeks after the
wildfire had been extinguished, are prevalent in regions like Southeast
Asia, North America, and Siberia.

They are driven by the burning of soils rich in organic content like
peat, which is a large natural reservoir of carbon. Worldwide, peat fires
account for millions of tonnes of carbon released into the atmosphere
each year.

Firefighters currently use millions to billions of litres of water per
to tackle a peat fire: The 2008 Evans Road peat fire in the USA consumed
7.5 billion litres of water, and the 2018 Lake Cobrico peat fire in
Australia consumed 65 million.

However, when water alone is used to extinguish peat fires, it tends to
create a few large channels in the soil, diverting the water from nearby
smouldering hotspots where it is most needed. This is partly why they
take can so long to be extinguished.

Now, researchers at Imperial College London have combined water with an
environmentally friendly fire suppressant that is already used to help
extinguish flaming wildfires, to measure its effectiveness against peat
fires at different concentrations.

During laboratory experiments at Imperial's HazeLab, they found that
adding the suppressant to water helped them put out peat fires nearly
twice as fast as using water alone, while using only a third to a half
of the usual amount of water.

Lead author Muhammad Agung Santoso of Imperial's Department of Mechanical
Engineering said: "The suppressant could enable firefighters to put out
peat fires much faster while using between a third to half of the amount
of water.

This could be critical in ending pollution-related deaths, devastation
of local communities, and environmental damage caused by these fires."
The results are published in International Journal of Wildland Fire.

The suppressant, also known as a 'wetting agent', increases the
penetrating properties of liquids like water by reducing their surface
tension. This agent is made from plant matter and is biodegradable so
it doesn't harm the environment.

The researchers mixed the wetting agent with water at three
concentrations: 0% (pure water), 1% (low concentration), and 5% (high
concentration). They used each concentration on a laboratory peat fire
with varying rates of flow between 0.3 and 18 litres per hour.

They found that the suppressant reduced the surface tension of the
liquid, which made it less likely to create large channels and instead
flow uniformly through the soil. Low-concentration solutions reduced the
average fire suppression time by 39%, and the high concentration solution
reduced it by 26% but more consistently. The average volume of liquid
needed for suppression was 5.7 litres per kilogram of burning peat,
regardless of flow rates or suppressant.

They also learned that the agent acts thermally and not chemically:
it encapsulates the fire to bring down the temperature and remove the
'heat' element from the fire triangle. The other two essential elements
for fire are oxygen and fuel.

Senior author Professor Guillermo Rein, Head of Hazelab at Imperial's
Department of Mechanical Engineering, said: "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. This magical suppressant could make it easier to put zombie fires
to rest for good." The results provide a better understanding of the
suppression mechanism of peat fires and could help to improve firefighting
and mitigation strategies. The researchers are now looking to replicate
their findings in controlled peat fires outside the lab in real peatlands.

This research was funded by the European Research Council and the
Indonesia Endowment Fund for Education.

Story Source: Materials provided by Imperial_College_London. Original
written by Caroline Brogan. Note: Content may be edited for style
and length.

Journal Reference:
1. Muhammad A. Santoso, Wuquan Cui, Hafiz M. F. Amin, Eirik
G. Christensen,
Yulianto S. Nugroho, Guillermo Rein. Laboratory study on the
suppression of smouldering peat wildfires: effects of flow rate
and wetting agent.

International Journal of Wildland Fire, 2021; DOI: 10.1071/WF20117

Link to news story:

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