Because the inverse reaction is empirically known to be exothermic, I was initially perplexed at how this could even be possible, until I read some of the other articles about microdroplets. (I’m not sure I understand the paper’s proposed mechanism TBH as it seems to be claiming to be exothermic based on an unshared simulation run).
It seems like a bunch of Stanford researchers in this lab are studying the whole hydrogen peroxide microdroplet thing, which is what makes this possible, because peroxide is a reactive specie that’ll make a lot of regularly endothermic reactions exothermic when used instead of water. But why do microdroplets produce peroxide when that is itself endothermic?
So my takeaway TLDR is, this may actually be a reaction between O3, N2, and H20. Or between H202 and N2. Ozone is not highly concentrated in air and is the limiting reagent (note that this experiment produced very little ammonia). So this seems unscaleable/impractical without producing large quantities of Ozone.
I’m an academia-pessimist and it seems like while in the past year a decent amount of research has come out debunking this whole “spontaneous peroxide” thing (it’s still cool, but it’s not a silver bullet and it makes results like these less impactful knowing it’s actually ozone powering the whole thing) the original groups of spontaneous peroxide researchers are pumping out as much microdroplet research as possible before everybody accepts it’s dependent on ozone. The newer papers should at least propose this mechanism in the name of intellectual honesty.
Each ozone molecule at 48g/mol I think will map to 2/3 of an ammonia molecule at 17g/mol. So you’d get 0.23kg NH3/kWh. And I found a link saying the actual Haber Bosch energy usage requires 26GJ/ton which is 3.6kWh/kg or 0.27kg NH3/kWh: https://www.sciencedirect.com/topics/engineering/haber-bosch...
Anybody feel free to check my math. Worth noting actual Ozone yields are supposedly much lower than theoretical maxes at around 12% efficiency (which may require cryo temps and pure oxygen under pressure) bringing yield down to 0.03kg NH3/kWh. Doesn’t seem to take lower electricity in practice considering this is only one energy requirement vs the haber Bosch process counting the full energy input, though maybe it’s less capital intensive. I guess Ozone is deceptively hard to make because the little ozone generators we use as disinfectants require very little actual ozone to do their job.
That could be a decent take if not for the fact that “green” energy is incredibly inefficient, and most of the world is anti-nuclear.
At the end of the day its not even about how renewable or energy efficient something is, it’s about what’s cheap. And multibillion dollar companies will always go for what’s cheap, regardless of the environmental impact.
Due to some newly discovered and not-yet-explained property of microdroplets (like a very high surface area:mass ratio) they readily react with air to produce peroxide, H2O2. The theory I’m describing, based on experiments testing peroxide formation at varying ozone concentration, is that the water molecules are reacting with the small amounts of ozone commonly present in air.
In chemistry, some molecular configurations are very stable and some are very unstable. Unstable things tend to react with other things in such a way that total stability increases; when it happens, energy is released (exothermic). Going from a stable configuration to an unstable one requires either a counterparty that was super unstable and became less so while reacting (still exothermic), or an input of energy (endothermic - basically never happens at equilibrium unless you’re directly applying high heat). However, just because a reaction is more stable at the end than the beginning doesn’t mean it will just occur, because in reality there are several stages the participants need to go through over an imperceptibly small time scale, some of which may actually require an input of energy to reach (activation energy).
Ozone is highly unstable but in air at STP, unless it meets another ozone, none of the normal molecules in air will react with it because they’re all super stable already (even N2, idk if the reaction can technically be exothermic but it has super high activation energy if it does) or O2 which couldn’t help it get more stable. It seems like new research suggests ozone can react with water at STP to form peroxide (H202). Water is normally quite stable by itself, but H2O2 isn’t.
I don’t think the proposed mechanism in the paper makes sense but my guess is that one catalyst is causing peroxide to decompose into H2 and O2 while releasing energy, as it is wont to do. Then we get the haber process H2+N2 reaction, which is technically exothermic but with very high activation energy. But fortunately the fresh H2 molecule has a lot of energy and the second catalyst helps reduce the requirements further. And 3H2 + N2 = 2NH3 which is ammonia.
In this video [1] (NOT describing the paper), the professor is explaining Integrated Ammonia Plants and at 46:40 there is a slide that shows the Theoretical Minimum specific energy requirement at 20.9 GJ/ton Ammonia and the state of the art (since 1991) to be between 24-26 GJ/ton Ammonia (which is an extract from a textbook, Chemical Process Technology, John Wiley & Sons, Ltd. [2]).
How does the proposed method in the paper compare in its energy requirements?
It would be maximally eco-friendly to transition agriculture away from chemical fertilizers (and pesticides, herbicides and fungicides/off-farm inputs in general) by focusing on soil generation and ecosystem development primarily through radical plant diversity/polyculture. For example,
https://www.youtube.com/watch?v=K8_i1EzR5U8
Cover crops, no-till & soil health - Quorum sensing in the soil microbiome (understanding the role of soil microbial interactions for soil health); Dr. Christine Jones
Early manifestations of this movement are in traditional farmers eliminating tillage/plowing ("no-till"); converting fields to rotations with diverse cover crops (not just a legume monoculture like soybeans, as has been practiced for thousands of years) to reduce or eliminate the need for fertilizers; reducing fallow periods through practices like "planting green" (sowing cash crops while the cover crop is still living), interplanting and companion planting; and use of fungal and bacterial biostimulants (application of cultivated strains of specific microbes and/or large scale brewing and application of compost tea). I view these practices as on the same spectrum as less commercially oriented approaches like permaculture food forests and foresee some kind of merger in the future.
Unfortunately, industrial influence will continue to steer research and advocacy toward hub-and-spoke systems (centralized fertilizer/GMO seed production + farmers selling into centrally managed distribution channels, or ultimately just the "growing" of calories in corporate-owned lab-factories) and away from distributed alternatives (farmers growing food using local inputs and nitrogen from the air via microbial activity + selling to local markets), simply because hubs allow for concentration of profit and control.
How do these approaches propose producing enough bulk calories in the form of wheat, corn, and rice to support 8 billion people? Also, how to the aim to overcome the labor issues in more developed economies? The labor inputs for these methods always seem to be FAR higher than conventional agriculture.
I've encountered less about rice, but the transitional practices I described can be used in the (otherwise conventional) growing of corn and wheat and can produce comparable yields for lower cost to the farmer, directly in the case of reduced fertilizer cost, but especially when you factor in reduced losses to drought events from the ability for high organic matter soil to absorb and retain water, as well as greater resilience to disease and pest wipeouts due to healthier plants and a more diverse farm ecosystem. It's all somewhat anecdotal, though, since this sort of thing resists formal research, both from the funding angle (doesn't lead to profitable results for industry; not sexy/high-tech enough for ambitious academics and their departments) and the experimental design angle (too many variables; farmers are all trying out different things in different ways and different climates).
From the permaculture/food forest/holistic side, you can certainly vastly beat the economic output of conventional agriculture (e.g. just growing corn) on a $/acre basis when you integrate all the possible enterprises available (meat, eggs, vegetables, herbs, fruit, wood products, flowers, ecotourism, etc.). I'm not sure in terms of marketable calories per acre, i.e. stuff human beings actually want to eat, but I'd think at least within an order of magnitude of corn (eggs go a long way). But you're right, the bottleneck is availability of farmers, since one farmer with machinery can grow hundreds of acres of corn or wheat at millions of calories per acre. I think it's fair to say there's plenty of opportunity for people to become farmers if they want to, though, in that information is more accessible than ever and there's land available.
We do have the example of Gabe Brown [0], who I believe manages 1000+ acres regeneratively with only his family for labor. I don't recall any attempts to calculate his kcal/acre, though. Farmers are understandably more concerned with $/acre.
I’m sure you can see big gains with no til methods and soil improvements, no questions there really. However every regenerative/organic farms I’ve ever seen uses tons of labor and often a lot of unpaid “interns.” I’m not saying it’s impossible to do this commercially without questionable labor practices, I just haven’t seen it.
I'm doubtful this is truly eco friendly. The quantities produced are so small that the energy costs of the sprayer system and catalyst become very high. Global production of ammonia is around 4 tonnes per second whereas this process produces 0.005g/m2 per second so you would need 800 square kms of catalyst to meet global demand (around the same area as Singapore).
I have my doubts about practical application, too, but the area of 800 km² need not be a show stopper if these things can be stacked, and that seems likely to me.
Also, if I understand https://www.pnas.org/action/downloadSupplement?doi=10.1073%2... correctly, the catalyst weighed 0.22 mg/cm². That’s 2.2g/m² or 2200kg/km² or less than 2 million kg for 800km². So, I guess the amount of catalyst wouldn’t be a problem either, _if_ it is a perfect catalyst that doesn’t degrade and doesn’t require regular cleaning.
Strong too good to be true vibes. Ammonia is an energy carrier, and in the conventional process that energy comes from H2. Atmospheric nitrogen and water are some of the most inert compounds in existence and that difference has to come from somewhere. Perhaps they just haven't identified the voltage or radiation yet? In a lab setting with an output that extrapolates to 0.005g/m2s, there can be a lot of inputs you just haven't successfully ruled out.
I did a deep dive in seeing how this is even possible, because it shouldn’t be thermodynamically, and it seems like all this “microdroplets allow for seemingly impossible reactions by spontaneously forming peroxide” is actually caused by ozone per some researchers: https://cen.acs.org/research-integrity/reproducibility/Claim...
This seems to be an open debate topic in chemistry. But I think it’s basically the case that, everybody knows it has to be ozone because the energy must be coming from somewhere, but knowing it’s ozone makes the dependent studies like this uninteresting (saying “who knows how we seemingly produced ammonia with little power, maybe this will cure climate change” gets your papers a lot more citations and recognition than “there is enough ozone in the air to produce small quantities of peroxide to use in reactions at STP”). Until it’s conclusively debunked people are gonna landgrab any paper that says “water violates all known laws of thermodynamics when you make it a microdroplet” to further their careers
I'm guessing it's just endothermic, and relies on the energy probability distribution on these droplets to have some atoms of high enough energy to react.
All of them seem like non-sequiturs, they have little relation to each other or to the comment they reply to.
The haber process doesn't require that the hydrogen comes from natural gas, and if you use other hydrogen sources and clean energy doesn't release CO2. From what I understand the popularity of natural gas simply comes from natural gas being one of the cheapest sources of energy. If you have cheap electricty you can just run a fuel-cell backwards, or electrolyse water. Electricity just happens to be more expensive than natural gas. Other processes will hit the same problem, since the overall energy requirement is the same. Whatever process we find needs the energy from somewhere.
Cool result. Although it looks like the mesh they used isn't disclosed everything else seems low tech, which would be good for mass production.
Is there any issue with removing nitrogen from the air like this. Does it only work until a minimum nitrogen contents?
"Water (H2O) microdroplets are sprayed onto a magnetic iron oxide (Fe3O4) and Nafion-coated graphite mesh using compressed N2 or air as the nebulizing gas."[1]
I was more interested if the supply of nitrogen in a local area would be effected. could you do it constantly in a shed or would you need some vents to pump fresh air in?
I am amazed by scientific progress as ever - and actually feel this is weirdly one of those papers where I stand a tiny chance of even being able to replicate it.
It's just that might be the problem (if it scales).
Isn't ammmonia the basic input to high explosives (I know it goes something like Fritz Haber -> Ammonia -> feed world / blow up shells), there is I expect a bit in the middle, generally fuel oil and fertilisers.
Going from ammonia to nitrate is still a fairly hard step - there's much easier home lab ways to produce nitrates, including methods that solely use air and water.
Could you please stop posting unsubstantive comments and flamebait? You've unfortunately been doing it repeatedly. It's not what this site is for, and destroys what it is for.
It seems like a bunch of Stanford researchers in this lab are studying the whole hydrogen peroxide microdroplet thing, which is what makes this possible, because peroxide is a reactive specie that’ll make a lot of regularly endothermic reactions exothermic when used instead of water. But why do microdroplets produce peroxide when that is itself endothermic?
I found a good explanation of this phenomenon (seems to be a hot topic in the Chemistry world in the past couple years) how it may actually be a reaction between ozone and water in https://pubs.rsc.org/en/content/articlelanding/2022/sc/d1sc0...
So my takeaway TLDR is, this may actually be a reaction between O3, N2, and H20. Or between H202 and N2. Ozone is not highly concentrated in air and is the limiting reagent (note that this experiment produced very little ammonia). So this seems unscaleable/impractical without producing large quantities of Ozone.
I’m an academia-pessimist and it seems like while in the past year a decent amount of research has come out debunking this whole “spontaneous peroxide” thing (it’s still cool, but it’s not a silver bullet and it makes results like these less impactful knowing it’s actually ozone powering the whole thing) the original groups of spontaneous peroxide researchers are pumping out as much microdroplet research as possible before everybody accepts it’s dependent on ozone. The newer papers should at least propose this mechanism in the name of intellectual honesty.