Fighting a wildfire with liquid nitrogen?

Poll: tell us your opinion

nitrogen fire suppression
Screenshot from TheBackyardScientist video, nitrogen vs. fire.

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.

One, the stuff is very cold. It has a boiling point of -320° F. Fire TriangleBelow that it is a liquid. Warmer than that it is a gas.

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.

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.
These Dewar Flasks for storing liquid nitrogen were some of the first to come up with a Google search.

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:

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

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The poll will close March 7, 2020.

Typos, let us know HERE, and specify which article. Please read the commenting rules before you post a comment.

Author: Bill Gabbert

After working full time in wildland fire for 33 years, he continues to learn, and strives to be a Student of Fire.

10 thoughts on “Fighting a wildfire with liquid nitrogen?”

  1. I think liquid nitrogen is more effective than water but would have to spend millions to billions for aircrafts that can dispense the nitrogen.

  2. So if I understand the arguments against presented in the article, they come down to:
    The people or animals trapped in the fire might get hit by a falling Dewar instead of the infinitely preferable roasting to death.
    It might make a mess.
    It will not put out fire for all time at the location where it is applied.

    Let’s be honest: the objection is “Not Invented Here”. No, one container of liquid nitrogen will not put out an entire 200K acre wildfire. Yes, you still need fire crews. Yes, refinements in application are needed. But I notice that Kidde already has a product out for interior fires so the idea is not entirely without merit. N.B. I’m writing this from Oregon, with two wildfires going within a 30 mile radius from here and an ugly orange sky. So it’s slightly more than a theoretical exercise for me.

  3. Water is not effective with these heats it just evaporates, maybe not nitrogen but there is other oxygen displacing inert gases and chemicals.

    Carbon dioxide
    Sulfur hexafluoride

  4. Hi I wanted to add a comment regarding the post for using liquid nitrogen to combat the fires.
    I personally think this is a serious possibility to the bushfire crisis and should be explored. The area of oxygen displacement is already well studied, we need to consider its possibility an option

    I am not at all discouraging our firefighters nor any effort to this 2020 bushfire crisis or previous fires there doing the absoloute best and more.
    I’m merely suggesting we put this to an open discussion publicly and consider other educated options because, were losing alot and quickly,

    The idea of oxygen displacement should be publicly announced and discussed.
    There is enough knowledgble people within Australia alone let alone globally who have specific and extensive knowledge about various gas and chemical compositions and with the help of major companies such as Boc we may have the resources to access immediately.

    On the topic of water, I will state a couple reasons below as to why I believe we need another option
    If you can further explain what I’m saying please do. It wont be all accurate, its just to my understanding

    2 parts hydrogen 1 parts oxygen.
    Hydrogen by itself is flammable.
    Oxygen is not flammable.
    Water works by creating a barrier between the oxygen and the fuel source and reducing the heat of the combustion
    When h2o ( water) exceeds tempatures of 650c ( may not be accurate) the atoms split leaving hydrogen and oxygen seperate.
    Hydrogen is flammable and makes the fire worse.
    Before that stage water evaporates at 100c and different articles have stated average bushfires can be around 1300c at base and around 400c at flame tip.
    Water won’t reach the flame base with this heat and will turn into steam which adds heat to the fire.
    Not enough heat to provide complete combustion.
    We have smoke because incomplete combustion.
    The fires not hot enough to consume all of the fuel source for complete combustion which leaves carbon monoxide.the heavy smoke That’s flammable and toxic
    Complete combustion leaves h2o and carbon dioxide.
    Carbon dioxide is non flammable, heavier than air and displaces oxygen.
    Water will evaporate before it can dampen a fire.
    Using waters aim is to reduce heat and create a barrier between source and oxygen but water won’t work with bushfire heats and also were in a drought, the more water conserved the better for our farmers.
    Other options that may be more effective are ideal and they are out there

    oxygen displacement,
    Nitrogen is non toxic and makes up a large percentage of our atmosphere so I agree with this man’s idea. Other inert gases like argon , carbon dioxide and nitrogen have higher boiling points then water. Argon is used with welding which demonstrates suitability to high temps. Other gases like sulfur hexafluroide aswell may be an option
    There heavier then air, highly effective for stopping combustion as it robs the oxygen which might be more effective then the purpose of water. If the right people come forward and we have an open public discussion about this and soon as possible

    The comment I’m Adding to, the person who suggested this idea mentioned using the wind to aid the delivery of the gases which is another positive over water

    No help immediately, further possible idea if anyone has knowledge or suggestions or knows someone who could please join this conversation soon as possible
    Using chemical reactions to turn the likes of the smoke carbon monoxide into potentionally substances like carbon dioxide which is also used in a fire extinguisher so it works as a potentional fire option. Turning the smoke into a resource or a fire retardant, through chemical reactions, from monoxide to dioxide.

    This shouldn’t be put down to just a vote for march in blunt honesty we should be discussing this very publicacly on all news and media outlets because the right people with this knowledge need to be used, and immediately within hours if the right platforms like the news channels are used we could be discussing and preparing other options like oxygen displacing gases

    Any thing that could help and save lives needs to be considered and now

  5. Agree with above, not practical on any large scale. As a former firefighter who now uses LN2 in my lab: LN2 is expensive, heavy, dewars are expensive and heavy, it evaporates and blows away in seconds (used to make fake fog) unlike “sticky” retardant….

  6. Not sure I’d call it lame, it is theoretically applicable, but has many real-world problems, most of which were cited in the article. Another being that serious fires often occur during high wind events, that would quickly dissipate the agent, and re-introduce fresh oxygen. Any experience wildland firefighter has experienced totally drowning a heavy log or stump hole, no way it could ever burn again, only to come back later and find it back on fire due to retained heat. I highly doubt it would reside long enough to fully cool the heavy fuels to the point they can’t reignite. Could have applicability in an enclosed or confined fire though, such as a mine shaft, interior of an unoccupied structure, hazardous confined space or something.

    1. Lame for most wildland fire applications, however, I happened to see this film on PBS last week, Also,

      This film should scare the crap out of anyone who watches it. Anyhow when a Titan II missile starts to leak it’s oxidizer and fuel a few truck loads of liquid nitrogen could come in very handy. The film is a great example of the Swiss cheese hole lining up analogy. Also a great example of situation of when not to defer to so called authority. Poor airman is told by genius expert at Strategic Air Command to enter the missile silo that is full of leaked fuel and oxidizer and to turn on a fan. The airman actually survived for a while. The warhead was found days later in a ditch.

    1. Please tell us any suggestions you have ?
      If it won’t work please tell us the actual reason why it won’t work so those who are trying can quickly invest time into the next possible soloution

      this time should be a time of kindness and support.

      Ideas might or might not work but at least there’s people out there trying to help with solutions that could help all of us

      Negativity is just time wasting and helps no one,
      Please be a bit kinder

      1. KD,
        I was not implying any negativity by my comment that you took the wrong way. I was laughing at how Bill classified it….”lame ass ideas”
        This will be my 22nd season in wildland fire and during that time I have seen a lot, and heard a lot of different ideas thrown out there.
        In no way will I ever try to explain the concept of using liquid nitrogen to control a fire. That’s for people who have degrees and understand chemistry etc.
        For my perspective, it’s the groundpounders who get the work done, assisted by air ops, heavy equipment, logistics, finance, safety, etc.
        Until those in power, admit and take immediate steps to combat global warming, climate change, the year round fire season, we will continue to see fires grow, and the familiar phrase, “I’ve never seen fire activity like that before” won’t be used anymore, because the fire activity of today is and will become more common place.
        The days of 50-1000 acre fires will be a thing of the past, and taking it place will be the mega-fires of 500k plus acres each and everyday. The destruction of both forest and WUI will be something unfamiliar to most…..
        So, again, negativity was not my goal….kindness is the overall objective of life…


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