Hackaday Prize Entry: A Fixation On Nitrogen

The reason we can feed six or seven billion people isn’t GMOs. It’s the massive increase in the use of fertilizers over the past hundred years. Most of the nitrogen-based fertilizers are produced using the Bosch-Haber process, a bit of chemical engineering that consumes one percent of all energy worldwide.

For his entry in the Hackaday Prize this year, [Peter Walsh] is improving the Bosch-Haber process, making the production of nitrogen simpler with less equipment.

The Bosch-Haber process runs at temperatures 400°C and pressures of about 200 atmospheres. Right now, this process is run in huge pressure vessels. [Peter]’s idea is to use ultrasonic cavitation to produce the same environment in equipment that can sit safely on a workbench.

[Peter]’s idea is inspired by sonoluminescence, a phenomenon seen when tiny bubbles in water implode producing light. It’s estimated that pressures and temperatures inside these imploding bubbles reach 2000 atmospheres and 5000°C – more than enough for the Bosch-Haber process. By injecting hydrogen and nitrogen into a machine that creates these sonoluminescent bubbles, ammonia will be created and turned into fertilizers to feed the planet.


The 2015 Hackaday Prize is sponsored by:

89 thoughts on “Hackaday Prize Entry: A Fixation On Nitrogen

  1. Damn … fertilizers are killing the soil, it’s really not that way we’ll feed the world. Better look at agroforestry and permaculture techniques that don’t need this kind of fertilizer. In Occident we are depleating our soils richness of microorganisms and nutrients, and we’ll soon be confronted to a desertification of the cultural fields. We need a change in our relation to nature if we want to survive as a species, not keeping at doing the same !

    1. The real problem is too many people, for the limited resources on one planet. And we can’t import matter from other planets. As earth’s mass increases it’s orbit would decay towards the sun, unless it’s rotation speed was increased.

      The two solutions are: Reduce the population to a sustainable level or populate a second planet.
      Mercury – 801 Fahrenheit (427 Celsius) during the day – nope
      Venus – 864 degrees Fahrenheit (462 degrees Celsius on average (due to the amount of greenhouse gases in the atmosphere) – nope, not without terraforming and sulphuric acid rain which evaporates before it hits the ground and 90x earth’s atmospheric pressure make that not an easy task for our current level of technology.
      Mars – summer day on Mars may get up to 70 degrees F (20 degrees C) near the equator, but at night the temperature can plummet to about minus 100 degrees F (minus 73 C).- no magnetic field means the solar winds blow away its atmosphere – maybe?!?!, but probably not.
      And as you go further out they are mostly balls of freezing cold compressed gas.

      Less people.

        1. This one tidbit is definitely wrong: the orbital rotation speed of a planet doesn’t depend on its mass (a way of “visualizing” that: centrifugal force is proportional to planet’s mass, attraction to the central star is also proportional to planet’s mass — in the equation it cancels cleanly).

          Of course, landing that much mass in the planet might change the planet’s momentum, thus its velocity and thus its orbit — you might want to be careful to “import” the mass from varying directions wrt the planet. Things to consider when doing very large scale geoengineering :-)

          1. “you might want to be careful to “import” the mass from varying directions wrt the planet.”

            Capture orbits coming in from “behind” the planet tend to be more energy efficient anyway, since if you come in “head-on”, it means you’ve got a *ton* of kinetic energy to bleed off. Now, it definitely could change the rotational (on its axis) speed, or muck with the Earth/Moon system, but…

            Seriously, why the hell are we talking about this anyway? The entire biomass of the planet is like, 10 billionths of a percent of the Earth’s mass. You’re never going to even budge it.

      1. This is probably a troll… but who cares, trolls need to eat too.
        Unless the laws of Nature have changed… Last I checked, Plants, Animals(including Human beings), Buildings, Cars, Houses, the display you’re reading this on, are all comprised of matter that came from earth, therefore having no affect on mass of the planet.
        However, apparently it is possible for humans to affect Earth’s rotational speed by increasing it’s moment of inertia (see Three Gorges Dam slows earth rotation). As for earth’s mass, according to an article (I found by Googling “Earth increasing mass” LOL) (http://www.bbc.com/news/magazine-16787636),That Suggests that Earth is actually losing mass, even though there are an estimated 41,000 tonnes of dust and other space debris falling to earth each year.
        You are right about the population being a burden on the Earth, after all it is like a runaway freight train.

        1. I think his point was if we imported food from other planets we would add matter and thus change our orbit.

          Which is a little silly imho.
          If we ever were to produce and import food to such a insane extent from other worlds, then we would almost certainly be exporting just as much matter as well – maybe even using some sort of counter-weight elevator system.

          But yes, I think everyone is agreed on the population issue, there’s only so much we can gain from efficiency increase’s. Even stabilizing at 10 billion that wont be sustainable forever – especially not if we want to raise people all up to 1st world standards of living.

          1. The goal should be to raise everyone to 1st world standard. The question that needs to be answered first is “what is first world standard?” Is it a standard where everyone has a gasoline car, or everyone lives sustainably.
            Farming techniques play a large role in sustainability and fertilizers and soil amendments are a part of every sustainable method of farming. Lightning fixes nitrogen. This method is a very admirable attempt to lower the energy debt for that fertilizer and this is a lead contender for the 2015 prize. The impact of this process would be enormous.

          2. I would not be willing to reduce my standard with, e.g. a gasoline car a big apartment, etc. OK, the car could be substituted by an electric one, if cost and range become adequat.
            So, if we want to be fair, this is what is to be considered as “first world standard”.
            Unfortunately the “Greenies” want to reduce us to a third world standard, with a bike instead of the car. No thanks!

      2. Saying less people is the solution is a cop out, its a lazy solution thought to work only by people in the first world who have enjoyed luxuries that in and of themselves are not sustainable. Real solutions look more like what this guy is doing, weather or not fertilizer is the answer, it is doing more to help the human condition than saying we should just let people in the third world kill themselves off.

          1. If we built cities with the same type of buildings as New York City, and maintained that population density (not Hong Kong, Tokyo, or Singapore which are much denser) we would only need about 269230 square miles to house everyone on Earth. That is almost exactly the size of the state of Texas! That would leave the whole rest of the world for farming.

            Secondly, while food security is an issue in the first world, food supply is a problem everywhere else. You also have the whole population issue of “the third world” consisting of at least double the number of first world people, depending on which model of where nations fall you measure by.

            So no, seriously, unless you are part of the humorous group who believe in population control by not breeding and committing suicide, than the statement that there need to be fewer people is saying “there need to be fewer third world people.” That you can’t see that is a nice first world privileged, isn’t it?

          2. It is a simple and readily understood concept that the human population has been growing and growing, and if it continues growing in the future, people will ultimately require more material resources including space in order to sustain themselves regardless of the socioeconomic conditions in which they live. This endless expansion in population is ultimately unsustainable, and improvements in efficiency or technology are really very short term patches to the very real problem of population growth. I’m sorry if it doesn’t fit into your philosophical beliefs, but people making more people infinitely is going to have to be curbed, whether it’s deliberately achieved by peoples’ actions or whether it occurs when we hit a “brick wall” of circumstances that we are unable to overcome.

      3. You left out two very interesting possibilities. While the surface of Venus is hellish, high in the atmosphere, at altitudes easily sustained by balloons, it could be quite temperate. And there is a region in Saturn’s atmosphere (not a moon, gas-giant Saturn itself) where the gravity is about 1G, the atmospheric pressure about 1 bar, and the temperature more earthlike than either Mars or Venus. Baloons required to keep you there, of course. And unlkke Venus, where solar is easy, energy sources would be a bigger deal. But there is a LOT of saturn to colonize.

  2. A very interesting idea that could probably be applied to other high temperature high pressure chemistry as well, but improving the Bosch-Haber process would have the biggest global impact.

    As history has shown if you lower the power consumption, in the short term less is used, but in the long term, more is. RPi for a simple recent example, short term less, long term more. Maybe government legislation could limit the negative future effects of such a positive idea.

    1. You can’t improve the efficiency of the process beyond the embedded energy of the products.

      The production of ammonia out of hydrogen and nitrogen is actually exothermic – it releases heat. That means the reactor runs itself once started. The heat and unreacted materials are recycled until around 98% of the stuff has reacted into ammonia.

      Once you got the ingredients, the process runs largely on its own without additional energy inputs, so the real question is how to efficiently produce the hydrogen and the nitrogen.

      Nitrogen is obviously not hard to make. The problem is the hydrogen, which comes from natural gas. The production of hydrogen represents the majority of energy inputs into the process.

      1. There is a better way of fixing nitrogen: azolla. I’ve been using it for several years in the high desert with great success. It is a tiny floating water plant that doubles every few days as it pulls carbon and nitrogen from the atmospheric CO2 and N2 and only needs trace minerals as inputs. High in protein and most agriculture animals not only love it but do quite well on high percentage of azolla feed replacing feeds grown using nitrogen created from natural gas using the Haber-Bosh process. If I could only find a practical method of drying it for storage!

        1. Electrolysis is not economical on the scales needed for fertilizer production. That’s why steam reforming is used commercially.
          Even if you used all the energy production from a large hydroelectric plant (that you owned) you could still not produce enough hydrogen, or produce it as cheaply as you can with steam reforming.

  3. Yesterday 5 billion, now 7, tomorrow 10. We are paving the way for war, deseases and famine. After all evolution works that way.
    We don’t need more food. We need less people.

      1. Then be the first to start saving the world, and stop living…

        Really though, you have been filled up with ‘Malthusian Propaganda’. Its old tool of the rich. Look into it.

    1. We’re currently wasting about 2/3 of the food we’re producing, directly and indirectly through overconsumption. We’re also wasting more than half of the fertilizers due to inefficient farming techniques.

      With improvements elsewhere, we could technically support a world population six times larger on the current output and resource expenditure without anyone going any more hungry than they are today.

      Well, the fat people would.

      1. I think we are wasting a lot more food than “just” 2/3, if you include the amounts used to feed animals (for meat).
        Animals are ridiculously inefficient at converting plant food to meat. (and need a lot of fresh water too)
        If you really want to tackle local food shortage, look at transport and refrigeration. There is plenty of food produced, but most of it is never consumed.

      1. More contraception, and less encouragement to bread. Better education on the issue. Social changes.

        Why does every time someone mentions overpopulation this crazy strawman about killing people comes up?

        1. The reason that the “crazy strawman” about killing people comes up is that many times before in history when perceived over population was a problem, people and governments often used persecution of certain socioeconomic groups as a “solution”. Including forced sterilizations, murder, and other tactics considered to be oppressive. It’s still happening today. —– And for what it’s worth, I AGREE with social policies that are restrictive of peoples’ breeding behaviors.

    2. “We need less people.” These are words you will never hear a politician say. And yet it is the planets biggest problem. The U.S. has reached zero population growth and yet we keep importing more people (about 1 million a year). If I speak out against it then I am branded a racist. It’s the same all over the world. The planet is screwed.

      1. Different issues.

        The amount of people the US can sustain is not directly linked to the amount the world can – those million people exist anyway. Denighing them entry to the US doesn’t make them vanish.

        It can be argued that people in the US consume a heck of a lot more then most other places, so more people in the US causes a higher world usage of resources – but thats not really a ethically sound argument. Its sort of saying

        “hay we are using more of the world then everyone….therefor we wont let you in because there will be more of us using more of the worlds resources”

        Or, in other words “I got mine”

        If you want to help the world moving people about is largely a non-issue.
        Focus on consuming less – 1st world countries need to get their consumption down per-person.

    3. Exactly. I expect you, your family and all the other trolls committing suicide by tomorrow to make this world a better place. That’s how evolution works. The sick die first.

    4. I’ve got one acronym for this talk of less people. MSR, or molten salt reactor, at 800C you can start thinking about everyday materials such as air a bit differently, like making “petro” chemicals out of air differently. Anybody wanna fund my tuition so I can switch from a physics/electrical engineering dual major, to a petrochemical/nuclear engineering dual major?

  4. The green revolution was about more than fertilizers. It was a massive host of technological improvements to an entire industry. What tech site would get that wrong? HaD, of course.

    1. The Haber-Bosch process is more or less directly responsible for about 80% of the nitrogen in our bodies, because it quite literally makes all that food production possible. Without it, none of the other technologies would have done anything for us – like having a car but no fuel.

      Before it was invented, the entire world had a population of 1.6 billion and we subsisted on bat shit deposits that were being mined in Peru and the Caribbeans. Without the Haber-Bosch process, we would have run out of nitrogen fertilizers in a matter of decades, and the great wars wouldn’t have been fought for a lack of gunpowder and explosives.

      We’d still be somewhere in the late 19th early 20th century in terms of technological and social development.

  5. The reasoning in these comments is not sound. You’re making the assumption that population increase is caused by cheap food, thus we should do nothing to make food production more efficient. Ridiculous! Just think about it for two seconds. By this logic we should outlaw tractors and go back to using horses for farming because this would increase the price of food. Or better yet, let’s impose food taxes, that’ll get people to stop reproducing.

    1. It isn’t an argument that we shouldn’t – it’s an observation that making food cheaper and changing nothing else will cause another population explosion – or rather accelerate the current one. Living cost is a limiting factor on population growth, if not the limiting factor. There’s a need for family planning on a global scale unless we wish to succumb into a state of society where most people are too poor to have children (yet try anyhow).

      The worst part of poverty-limited population growth would be the fact, that when so many are so poor the people will stage an uprising to re-distribute wealth in the name of social justice. A new communist revolution if you wish. The end result will be total collapse of society as the public ownership of all resources turns into a tragedy of the commons. People get a bit of extra resources by taking them from the rich, so they breed more until they’re back to square one and then absolutely everyone is poor and nobody has the resources to do anything.

      The real point is that we’re facing a hard fact: if we don’t limit population growth by other means, poverty and hunger will inevitably do it for us anyways. If we do limit population growth, making food cheaper isn’t really all that important. It’s already cheap enough.

      1. “it’s an observation that making food cheaper and changing nothing else will cause another population explosion – or rather accelerate the current one. Living cost is a limiting factor on population growth, if not the limiting factor.”

        It’s an interesting topic, I hear what you’re saying. I just don’t think the right way to limit population growth is to stifle technological improvements. Obviously you’re more or less in agreement on that point I just hate that this guy’s project is being overtly discouraged by everyone.

      2. Numbers prove you’re wrong. The less future security people experience the more they will reproduce. Birth numbers in Europe dropped markedly in the sixties when the economy had finally recovered fully from WWII. For many people having a large offspring is still the only viable pension plan.

        1. On the contrary. While the society was in ruins post WW2, there were so many opportunities and jobs to be had rebuilding, and so many people dead that there existed a social vacuum where you could have more children and expect them to find work and sustenance. The result was the post-war baby boomers.

          Today those same baby boomers are depressing our population growth by dying faster than new people are getting born. It creates an illusion that the population is staying stagnant when it’s just returning to its normal growth trend. Once the boomers are gone, the growth continues.

          Humans don’t switch over to the quantity over quality breeding strategy until we’re literally so poor that the only way to keep some of your babies alive is to make more of them, but that’s well into the starving african territory when society has already collapsed.

          1. Point in case: the same baby boom happened both in the US and Europe, fueled by the massive amount of resources and manpower freed from the war effort, put into rebuilding, coupled with the millions of dead people no longer in need of food or clothes. While there were shortages of some goods such as petroleum, the overall effect was lowering the cost of living to the great many.

            The war was also a great re-distributor of wealth since the top echelons of society had to start spending their accumulated wealth to re-build their empires and that meant more to go around for the little guys. The eventual economic recovery just meant that the money collected back up top and away from the people at large.

            Today, the slowdown is largely caused by growing income inequality. Where after the war 60 years ago mom could stay at home and dad made all the money, today you need both parents working and still they can’t make enough to support a large family.

    2. Population growth follows a well analyzed and predictable curve. Population growth is not exploding or growing exponentially. Rapid population growth is what happens when previously high infant mortality rates drop suddenly because of better access to food/medicine, but the cultural norms of having lots of children to compensate for that rate lags behind. Population dynamics change over the decades and eventually settle on lower birth rates.

      This trend is already happening in China and India. The worlds population will settle around the 2050’s.

  6. Pretty much everyone I know has several points during the day when ammonia/nitrogen producing liquids pour out of one end of their body. For some reason most of them just flush these away to be expensively processed somewhere else.

  7. I think the temperature of sonoluminescence is way too high for any chemical reaction. Also, there must be some figures relating to the efficiency of sonoluminescence effect which will either make this idea viable or not.

    1. The temperatures stated are simply calculated based on the spectral emissions of noble gases in solution (argon typically) and are not indicative of large quantities of heat being produced. The small number of ionized particles in the sonication bubble contribute very little heat to surrounding atoms / molecular species.

      The amount of ammonia formed through ultrasonic cavitation is measurable, but the process is not suited to increased scale on the level required for agricultural applications.

      http://www.collectionscanada.gc.ca/obj/s4/f2/dsk1/tape3/PQDD_0016/MQ57783.pdf

      http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=AD0701439

      http://pubs.acs.org/doi/abs/10.1021/ja01158a532

  8. Im shocked at the amount of people suggesting ‘less people’. not enough food and water? off a few million. too crowded? concentration camps take care of that. This is a f#cking article on fertilizer. A rather interesting one at that. cant we have one discussion about feeding people where the mostly popular answer isn’t mass genocide?

    1. Because it is unfortunately ‘easy’ to say ‘people must die’ yet still give the appearance of being intellectual. But they care not for it will not be them who is dying right? It is like ‘zombie plans’. Everyone thinks they will be the one hiding in the bunker. But the reality is they would be the one going ‘braainz’. We are the mob. We are the ones who would be herded up and killed. Anyone who thinks ‘thats a good idea’ should read up on the Japanese and Nazis in WW2. Mass killing is not a ‘good thing’ as you point out.

      Fertilizer has transformed our world. It allows people to live places where they couldnt before. It allows us to build better things. This process sounds like it uses less energy (therefor less greenhouse gases). We should be praising it. To say we should use less is not in our nature. Whenever I hear ‘people should use less’ I always add ‘except for me’. Then the statements make sense because it is pure greed.

      1. “Whenever I hear ‘people should use less’ I always add ‘except for me’. Then the statements make sense because it is pure greed.”

        Same reason your hearing “people must die”

        Its voices in your head that NO ONE is saying. ;)

        People should use less does not mean our quality of lives needs to go down. Technology often means we dont have to make that choice. Often its just the uneven spread of technology, initial investment, and human stubbornness.

        We can have nice things AND use less in a lot of cases. The idea that anyone suggesting we need to consume less is suggesting that they themselves shouldn’t have too is nuts.

        1. Agreed, as an example automobiles today produce more MPG and HP than cars made in 1970 and on fuels made so much less dense as to render those 1970 cars 6 mpg gas pigs.
          As for all those genocide proponents I say You go first.

        2. No, the reason some people are reading “fewer people” = “people need to die” is because that’s what most people mean when they say that. You don’t? Congratulations, you are more enlightened than the masses and somethingsomething blahblahblah crap to appease your ego.

          Secondly, unless you are part of the first world problem, USING LESS DOES MEAN LOWER QUALITY OF LIFE. Period. So, you go first. Get rid of your 40MPG car for something that gets 60 or better, and give that 40MPG one away to someone who can only afford a beater car. Can’t find someone without a newer car? Then leave the suburbs, those are a huge part of the food problem too.

      2. This process doesn’t use less energy. It uses more energy, and is not scalable to the level required to be useful to agriculture. This process has been studied since the 50’s and is still a lab novelty.

      1. Maybe you could take it as a clue that so many people read it that way as a clue. See that perhaps you and the folks making the statement might need to find a different choice of words. Or you can tell people to quit; that’s sure to work.

        1. Too many people != mass genocide. It means less children, plain and simple. Having a large family is as good as murder nowadays because there will soon be a point that the planet cannot support those people. Smaller families (2 kids or less) = population control. Some attempts have been made worldwide, but everyone who suggests “global population control” gets lambasted by the straw hat bastard with 8 kids comparing him to Hitler.

      1. (Bosch-Haber is my project)

        I have a few things that I want to try, and that’s one of them.

        Check out my back-of-the-envelope calculations for efficiency. In summary, I need a factor of about 25,000 improvement in efficiency to be interesting:

        https://hackaday.io/project/4689-improve-the-bosch-haber-process/log/16096-back-of-the-envelope-calculation

        Certainly I’m not going recreate Supeno’s work and expect to get different results. I’m going to try things he didn’t think of.

        And yeah, I know this is a long shot, but I enjoy the process.

  9. Hi! I’m a farmer! The agricultural industrial compex is hard at work gearing up to boost crop yields to support all the billions of new humans soon to arrive. No need for mass extermination for a few more generations at least. The permaculture guys have some good ideas to, no reason we all can’t get along.

    The project reported above is really interesting. Its a long shot but every possibility needs to be persued.
    For a great read about the history of Haber, Bosch, their invention that saved the world from starvation and enabled two world wars, check out the book: The Alchemy of Air by Thomas Hager.

  10. I’m here to talk about the prize-entry.

    “The process runs at 400°C and pressures of 200 atmospheres, and is energy intensive. The compressors and reaction vessels are wildly expensive and wear out over time, a great deal of energy is used for compression and heating, and the resulting yield is only about 15%.”
    “The sonoluminescence setup seems like an inefficient method. A more practical way would be to use an ultrasonic transducer connected to a horn which causes cavitation directly, in the manner of an ultrasonic mixer.”

    I don’t think the metal of the vessels likes cavitation…
    Generally, efficiency of a thing with massive moving parts @ high freqs < efficiency of a thing with little moving parts

    "For this project I intend to design and build a system capable of ultrasonic cavitation within a reaction vessel, see if it's possible to convert Nitrogen and Hydrogen into ammonia, and see if this can be done more efficiently than Bosch-Haber."

    'Hope it will efficiently catch C02 too !

    I not here to do some bashing mind you, this is a very interesting chemical experiment, much more prone to errors than the common breadboard with an a……(oh no, another debate!), but common ! I would have expected more humility : it is very unlikely to be a revolution ! Instead of talking about "improvement", the idea that the ammonia produced "will be created and turned into fertilizers to feed the planet" (and recreate in the meantime the same debate about the environment), why not see this as a nice and quite exotic(!) experiment ?

    Atom fission is cool to study, and have nice natural effects … but on the large scale, 'not drawing a pict.

    "For his entry in the Hackaday Prize this year, [Peter Walsh] is improving the Bosch-Haber process, making the production of nitrogen simpler with less equipment."

    HAD, I know the news tends to do the same, but be honest, don't overdo it ! This is a nice, esotheric experiment. Period.

    EVERYONE can locally produce ammoniac, "with less equipment" than industries, by a process called …"slurry and manure distillation". Let's talk about efficiency when this project will effectively produce ammoniac.

    [note:I know I'm not a native]

    1. Finally! Someone noticed that!

      I expected to get upbraided for it weeks ago… and nothing happened.

      (I’m using it as a metric to see how many people already knew about of the process.)

  11. I think the O2 in the water will partake in the reactions and you will not get NH3, but if you are very lucky you may produce N2H4O3 directly.

    Just assume the set-up will explode when you run it and take the appropriate precautions. :-)

  12. Interesting. Can’t imagine it will be very efficient, but I still like the idea of eliminating the pressure vessel. One thing I’d like to add some info on:

    “Nitrogen and Hydrogen are largely insoluble in water, but ammonia is very soluble in water.”

    I don’t know about nitrogen, but the low solubility stat for hydrogen can be a bit misleading. The amount of a dissolved gas in water is measured in ppm(w), where w=weight. Contrast that to the more familiar ppm(v), where v=volume, in air. The (w) and (v) are usually omitted, leaving just ppm for the measurement unit in both water and air, though the measurements are different.

    Yes, the solubility limit for hydrogen in water is low. But remember that’s in ppm(w). And hydrogen weights very little. So you can actually dissolve a greater amount of hydrogen in water, by volume, than you might suspect.

    Exactly how much, I don’t know. But at one point I did an experiment where I dissolved CO2 into the water of a planted aquarium to boost plant growth. The CO2 was generated electrochemically, with a greater volume of H2 as a byproduct. The gasses were dissolved by trapping them in a reactor in which water was churned. At first I was concerned that because H2 was “nearly insoluble in water”, it would build up until the reactor completely filled with it; then both H2 and CO2 would burp out, wasting the CO2 I wanted. But that wasn’t the case. The H2 dissolved just as easily out of the reactor as the CO2.

  13. This site lists the solubility in grams of gas per kilogram of water:

    http://www.engineeringtoolbox.com/gases-solubility-water-d_1148.html

    Ammonia comes in at 400g/kg, Nitrogen is .015g/kg, and Hydrogen is .0015g/kg.

    (Ammonia molecules have 8.5x the mass of hydrogen molecules, but that’s still a big difference.)

    This is one reason I think there’s some room for exploration. All the published sonication experiments that I can find used gases dissolved in water.

    I want to try a physical setup that doesn’t rely on dissolved gases.

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