A science blog with Eric Berger

Much more on the amazing use of electricity to put out fires




Here, then, is my conversation with Cademartiri, who insists I didn’t butcher his name.




I thought “Well, that’s weird.” As a scientist you find it fascinating, but you have to control your emotions and ask how nature is trying to deceive you. I was thinking, “What is wrong with this experiment? What did I do wrong?”

How strong was the electric field?

The electric field we used was on the order of a megavolt per meter, which is close to the breakdown of air. It’s essentially the field you witness whenever you get a spark on your fingers when you try to open a door.


The first time the fire went out, Cademartiri thought something had gone wrong.

Like if you get a shock from someone or something?


So it doesn’t take that much energy to generate that kind of an electrical field.

The energy that goes into a system of this kind comes from two sources. One is the voltage. And the other one, that turns out to be more important, is the current. Essentially in order to oscillate a voltage on an electrode you have to drive a current through the electrode. Then this current will increase with the size of an electrode, so if you have a larger electrode, you would need more current to bring it to a higher potential. Our amplifiers were 600 watts, that’s the power required. We think that, from of our experiment, the results wouldn’t change too much if we decreased the current by 50 percent or so. But we haven’t looked into it yet, and we have a lot of work to do.

How large was the methane flame?

It was larger than a Bunsen burner. The geometry of the flame was the same, it was conical. The largest flame we could fit in our setup was 50 centimeters tall, that’s a foot and a half. We only now are starting to look at how this effect scales with the size of the flame.

Where did the idea come from? One does not think commonly of using electricity to fight fire.

The strategy of looking at flames in unconventional ways came from Professor Whitesides. There is a history of scientific reports on the effects of electric fields on flames, but the effects were very small because people were using DC voltage, fields that are static over time. What we discovered is that by applying an oscillation field, AC voltage, the effects are completely different.

How might the electric field disrupt the fire?

Hydrocarbon flames produce charges spontaneously in the form of electrons, ions and charged soot. We also know that electric fields interact with charges. What happens is the electric field is essentially driving particles like bullets in the air, very fast, and in this movement the charges will bounce off all the other molecules which make up the air within the flame, and the immediate surroundings. What we have discovered is that this collective motion of ions leads to a coherent flow in one direction. You have the onset of flow within the flame that is the really interesting part of it.

It seems almost magical that you’re waving a wand at a fire and it goes out.

There are things that when we first look at them they do look like voodoo or magic. But in the end, when one realizes that it goes out because we’re generating a flow within the flame, and that this dislodges the flame from its fuel source, it is not magic.

You’re doing things that were not known or possible before in terms of creating this flow within the fire.

This flow is actually the thing we are most excited about scientifically. We have developed a new capability with respect to flame. The capability is that we’re able to generate localized flows within the flame, and these flows can be strong enough to put out the flame or affect it in other ways. These flows originate just from the motion of the ions, and they can be generated with no moving parts. Usually when you want to generate a flow of air or gas, you need a moving part, a fan or something like that. In our case we can do it without moving parts. This has significant implications if you want to apply this technology in certain environments, for example environments at high temperature.

Is this potentially applicable to fire control in houses or aboard ships?

Were considering all kinds of scenarios. We’re only now starting to look at how this effect scales up, so it’s very early to say. Our survey of all the mechanisms participating in this interaction is not complete. Our understanding is not 100 percent complete, but I believe we have gotten a good grasp of all the key mechanisms.

All the same, do you have a hypothesis?

Not yet. We also haven’t played a lot with many parameters like the shape of the electrode, so it’s very early to say anything for certain.

But it’s certainly a very tantalizing prospect.

Yes. Our entire hypothesis from the beginning is that flames are not as widely recognized as they should be as one of the key chemical processes we know of. That’s not just because of its historical importance. Combustion still represents 90 percent of our energy supply. If you look at energy production, 90 percent of it worldwide comes from burning stuff. When you look at the enormous importance that combustion has, our hypothesis was that if we could find any new way to control flames in a novel way, we have a real chance to make a real big impact. This is our hope and we think it’s the right direction to go.

When do you expect to work with larger fires?

We cannot really work with larger fires in our lab, so we are collaborating with the Naval Research Laboratory in Washington D.C., with Dr. Jim Fleming, and they have a large facility. They are providing us with lab space and an enormous amount of expertise they’ve developed in working with fires over the last 50 years. We did the first tests in February and are looking forward to do more.

And you’re still optimistic after those further tests?

I’m very optimistic that something very relevant is going to come out of this new capability.

Categories: Chemistry
Eric Berger

26 Responses

  1. ntangle says:



    So the oscillating field reduces the ions’ turbulence? IOW, if they becomes more laminar, maybe there is statistically less contact with oxygen…less opportunities for fuel ions to oxidize.

  2. JohnD says:

    Great interview, Eric! This should be something to watch as the science develops over the next decade.

    And his hint of new propulsion sources (“Usually when you want to generate a flow of air or gas, you need a moving part, a fan or something like that. In our case we can do it without moving parts.”) is perhaps the most exciting part of it all.

  3. Eric Berger says:



    I agree. Two really good reasons to take this seriously are that it’s in the lab of George Whitesides, who is probably the most productive living chemist in the world, and the fact that they were able to move so quickly into the NRL facilities in D.C. That tells me the work has legs.


  4. Mark S. says:

    Not really new thinking here as Tesla coil builders have experimented with magnetically quenched spark gaps for years.

  5. Steve C. says:

    Two things struck me. One, this is an amazing discovery with remarkable implications, and two, he looks like Johnny Depp. :-)

  6. ralph says:

    I just hope in all this enthusiasm they remember to never, and I mean *never*, cross the streams!

    Why, you ask? It would be bad.

    How bad? Try to imagine all life as you know it stopping instantaneously and every molecule in Katy exploding at the speed of light.

  7. Bill in Houston says:

    I’m surprised he didn’t set those locks afire…

  8. Corey says:

    I wish you’d asked him which plasma drift mechanism they thought this was. An RF field in a plasma will cause a drift? I haven’t got Chen’s book beside me to remember which one it might be.

    If it’s a new phenomenon in plasma, then it’s VERY interesting indeed.

    I just did the capacitively-coupled RF plasma lab experiment as a grad student at UW-Madison and I don’t recall any coherent drifts, so I’m pretty curious.

  9. Rorschach says:

    This is the magnetohydrodynamic effect. it is using the electric field pressure to push the ionized gasses around. Been known for a very long time. First discovered in 1942.

  10. Rorschach says:

    I don’t think this will scale well to the real world, because you need a “target” for the electric field on the other side of the flame.

    This is by the way very similar to a thermonically heated vacuunm tube.

  11. hunter says:

    This could be really huge in a lot of areas.

    Think of how this might be used to manage industrial chemical processes, biochemical processes, not to mention safety issues of all sorts.

    With high speed processors, what about internal combustion and turbine power sources?

  12. xxx says:

    I thought politics accomplish this, “…and the fact that they were able to move so quickly into the NRL facilities in D.C. That tells me the work has legs… [no legs needed]”

    As said before year ago, after you turn the gadget off the flame returns unless:

    1) You shut off the fuel

    2) Take away oxygen ***** OR ****

    3) Cool the fuel below its flash point [for drilling rigs the heat from the platform restarted/(flashback?) the fire after the oxygen returned from the explosion]

    Ps mehtane is a gas, an oil fire that has the heat on the surface will reignite like the drilling rig from its own heat

    But it is nice to remember.

    Combine this and the radio waves for water fuel and maybe we can “create” fire efficiently

  13. JAy. says:

    @hunther – internal combustion control was also what sprang to my mind. Not sure how strong the capabilities would be with regards to a reciprocating engine. But there may be significant potential for continuous flame applications like gas turbines or some sterling engines. Managing the flame front with electromagnetics could be very interesting. This flame front control is currently the method for generating low-NOx burners. A whole new potential could now emerge.

  14. Hello everybody,

    I am Ludovico Cademartiri, one of the members of the team working on Flames in the Whitesides lab and the interviewee. Feel free to ask me anything.

    to Bill: My hair are still fine… for now :-)

  15. Daniel Smith says:

    The most exciting phrase to hear in science, the one that heralds new discoveries, is not “Eureka!” (I’ve found it!), but “That’s funny…” – Isaac Asimov

  16. correction: I will answer what I can :-)

  17. Rich Abercrombie says:

    Dr. Cademartiri –

    Thanks for taking questions from readers. I hadn’t thought about the potential for combustion improvement. By controlling the flow of a flame, theoretically could one improve efficiency of combustion? I.e. could we get more energy out of fuels?

  18. xxx says:

    Ludovico Cademartiri “…which we pointed at the base of the flame…”

    Was the current in contact with the orifice (metal)? Can you bring the device down with you to the Final Four this week end, we have the beers?

  19. Dear Rich

    this is early to say. In other words, we (the group of Prof. Whitesides) have not looked yet at this area of application but we are certainly considering it. We have a lot of work ahead of us…

  20. ntangle says:

    Appreciate the opportunity, Dr. Cademartiri. This is a very interesting phenomenon. You’ve already given some #’s, regarding the e field strength and the power levels. What range of excitation frequencies was most effective?

  21. Hi ntangle

    we are limited in the frequency range that we can access by the speed of the amplifier (slew rate). The maximum frequency we can use (at maximum voltage) is about 2kHz, so, still relatively low frequencies…

  22. ntangle says:

    Thanks. Since you mentioned slew rate, you implied something that I’d considered asking. ie., what waveform(s) are you using, a sinusoid or whatever. If slew rate is a consideration at a rep rate of 2kHz, then you’re apparently using square waves or a pulse train. And/or you’re limited by the output transformers used to provide the desired voltage.

  23. ntangle says:

    Of course, I could be wrong as I have no idea how much reactance the output would face in a plasma at those voltage levels. BTW, I built a flame loudspeaker when I was in school, driven by ~150W at higher frequencies (beyond 20kHz), but of course, nowhere near those e field strength levels.

  24. ntangle: we have the fastest amplifiers on the market (750V/microsecond) and, when you add a little bit of load on the output (the electrode) the slew rate goes down to about 300V/microsecond (which is still very good) – This causes slewing of the signal above a few kHz.

  25. Garrett Toren says:

    So now firemen can point a wand at a raging forest fire and put it out? Do we have to worry about someone pointing it at the sun?

  26. PDQPete says:

    “Electricity” my foot–I suspect the surreptitious use of magic.

    Well, I mean, just *look* at the guy!…