At Wildfire Today we have written about many out-of-the-box proposals for suppressing wildfires. Now a new method (to me anyway) is being proposed.
Kenn Roberts wrote to us from Whitehorse, Yukon, Canada suggesting that liquid nitrogen could be used to help control the bushfires in Australia.
There are two ways the application of liquid nitrogen could retard the growth of a fire.
Two, if it is present in enough quantities it can displace oxygen. Either of those would remove one leg of the heat/fuel/oxygen fire triangle.
Liquid nitrogen is heavier than air and will initially stay near the ground or sink to lower levels. After the gas warms to the ambient temperature it becomes slightly lighter than air and will rise.
There are videos online (of course) of people playing with liquid nitrogen. A couple of them are by TheBackyardScientist who puts out flames from a tiny “flame thrower” like in the photo at the top of this article, and a burning flammable liquid on the surface of a swimming pool.
So obviously in a small controlled environment liquid nitrogen which has boiled and produced gaseous nitrogen can under some circumstances put out a fire. However (you knew there was going to be a “however”) adapting that concept on a very large scale to suppress a wildfire would prove to be challenging at best.
Mr. Roberts says nitrogen could be used by firefighters on the ground “to dispense liquid nitrogen and/or use equipment to propel liquid nitrogen into hard to get to areas.” And, he explained, “it can be carried in the direction of the wind.”
Used from the air, he said, “Heli/ fixed wing can drop liquid nitrogen canisters directly on fire, in the path of fire, or use to be carried with the wind behind the fire.”
Dewar flasks can store liquid nitrogen for a matter for hours or up to a few weeks.
Putting aside the ability of nitrogen to suppress a wildfire, there are practical, logistical, and safety issues to consider. Whatever container is dropped from an aircraft to deliver nitrogen to a fire, it could only be deployed in an area devoid of anything or anybody that could be harmed by the objects falling from the sky. In addition to physical damage from the falling Dewar flasks, if the gas spreads to an inhabited area the displacement of oxygen could be a concern, perhaps even resulting in death. Also the effects on animals and other environmental factors would have to be considered. And like the proposal for aircraft to drop boxes of retardant on a fire, the containers, debris, or equipment would have to be removed.
Mr. Roberts submitted his liquid nitrogen concept to the California Department of Forestry and Fire Protection. Curtis Brown, Staff Chief for Research and Development, wrote back to him on December 10, 2019. Here is an excerpt from the letter:
A great deal of thought and consideration went into reviewing your liquid nitrogen technology proposal. After careful review of the proposal, it was determined that CAL FIRE will not be able to pursue this project. While your idea is intriguing, CAL FIRE does not have the resources or budget to pursue the implementation of the application. The hazards of working around nitrogen is a fundamental safety concern and your proposal lacks details regarding how to safely administer this technology.
Undeterred, Mr. Roberts said he plans to conduct a demonstration for structural firefighting in Whitehorse, Yukon, Canada.
Here are some wacky ideas for putting out wildfires. All were tagged Lame-Ass Idea:
- Truck with dry chemical extinguishing agent
- Disposable air tanker
- Retardant in boxes dropped from an aircraft
- Fire extinguisher bomb
- Truck digs dirt and throws it on a fire
- Howitzer and artillery shells
What do you think? Should we file the liquid nitrogen proposal in the Lame-Ass Idea category? To vote below, click on one of the two choices, then click on the hard to see “VOTE” button which is above “View Results”.
Is fighting wildfires with liquid nitrogen a Lame-Ass Idea?
- Yes, it's a Lame-Ass Idea (88%, 114 Votes)
- No, it's a great idea (12%, 16 Votes)
Total Voters: 130
The poll will close March 7, 2020.