Just to spell out something that's been implicit in other comments: the entropy level of your energy matters a lot. Electricity > movement > heat. To go down the chain is almost free, to go up the chain you have to spend quite a lot.<p>You can do a lot of things with electricity: you can heat things, but also move them around and run your TV, all without any loss. With heat you can just... heat things. So you can't call this an "iron battery", because you don't get electricity out of it, just heat. Maybe call it a "heat battery" or "high performance heat pad".<p>Also note the efficiency numbers: "High-efficiency electrolysis of iron oxide can store as much as 80 percent of your input energy in the iron fuel" is the efficiency of the process itself. "Using this kind of cyclical process to generate electricity could approach a theoretical efficiency around 40 percent" is because you need to climb the ladder to low entropy again (probably by using the equivalent of a steam engine to run a generator).
Interesting - essentially the iron is oxidised to release energy, then deoxidised using renewable energy. So it's another way of buffering renewable energy, which doesn't require a large body of water to store it. I'd be interested to know the overall efficiency of the process, but it sounds great - on the surface.
Remarkably good science journalism - I appreciated the caution at the end about the economics of the process and the understanding that there are many different factors that can make a process attractive.
Using more ... aggressive metals might help energy density here, though it would require more energy losses during rebuilding the oxides.<p>Now before one points out that burning lithium just makes this a battery; kinda but also no. If you burn lithium to turn a generator, I'd argue it's not much more a battery than burning oil to turn a generator. If you wanted a battery, you'd need a non-generator variant. That is where I'd differentiate.<p>Could also use Flourine and burn CO2, might be a viable carbon sink. Flouroalkanes from burning CO2 would be organically inert, don't deplete ozone if released and don't bioaccumulate. Only downside is they're very good greenhouse gases if you don't burn them down to the alkanes that are solid or liquid are normal temperatures. Those you could easily bury deep below the earth.<p>The only issue is obtaining a shitton of flourine to burn your carbon with and then not blowing yourself up in the process.<p>(Also yes, Flourine will burn CO2 and act as the oxidizer)
I have seen this story in several outlets, but haven't heard about NOx emissions from this process. Could someone more knowledgeable shine a light on this?
Efficient cycles to store heat/cold will be very valuable in the next few years. There are a lot of industrial/logistics processes where by far the biggest energy usage is in heating/cooling. In a recent refrigerated warehouse 40% of the electricity is coming from solar panels on the roof. Going higher than that is not economical because energy will be sold too cheap to the grid and batteries are still too expensive. But there are solutions starting to appear to store cold while the sun is out and then release it over the night as needed. If we can get a lot of these types of loads working like that switching the grid to solar can go even faster because of not having to wait for cheaper grid-scale storage.
I'm most interested in the the rust->iron electrolysis process - neither the article nor the video describes how that's done, except to mention that the process used clean electricity. Certainly it's possible, but I don't think there's much electrolytically produced iron today. I wonder if they're using a process that requires the oxide to be melted (very simple but needs really high temps) or a lower-temp, more chemically involved process. If they have a good-enough way to produce elemental iron, it seems like replacing an existing coal/gas fired iron smelter with a renewable electrolytic one would be a cool experiment too.
So it's more of a battery rather than a fuel. I wonder what the energy density and longevity is compared to other industrial batteries. On a side note, what's the point of a brewery (single business) using it? Do they have some unique energy requirements?
How much iron is wasted in the process? I’m pretty sure they are not able to recycle 100% of the oxide and there must be some material losses.
Also what temperature do they need ? I assume they are making their own bottles so I wonder if a much more simple process to heat up using electricity directly would not be more efficient?
I really doubt the claim about 80% efficiency of converting iron oxide back to iron. Industrial processes widely used today are based on fossil fuel (natural gas or coal). There is some research on electrolysis, but this process is not an easy one either: you have to heat oxides up to 1600 C, apply electricity, extract resulting iron, cool it down, powder it. Each step takes energy, so I guess the 80% are only for the electricity part, without accounting for other required steps.<p>And how do they get the 40% round-trip efficiency? Even if we assume the 80%, modern gas turbines have efficiency of up to 38%. In complicated combined cycle mode plants efficiency can be boosted up to 60%. And it is natural gas, a very convenient fuel to work with.
for those wondering why more applications do not source metal as a fuel, burning metal is frighteningly difficult to extinguish.<p>metal fires often burn at more than 5000 degrees F. That’s hot enough to disassemble water into its component parts, and one of those parts is hydrogen gas, which is not only flammable but explosive. any uncontrolled release of liquid into the fire would be catastrophic. Metal fires cannot generally be quickly extinguished in an emergency or uncontrolled accident.<p>metal fires also release toxic gasses and byproducts that often require more consideration than electric or gas.<p>as an update to a few questions: NEVER add water to a metal fire. it will cause an explosion.<p>depriving the fire of oxygen works, but only insofar as it remains deprived until the fuel source cools from 5000 degrees, or it risks spontaneous reignition. it generally has to be monitored similar to a crucible as it cools.<p>most accidental metal fires do not have a cogent or quick option to deprive the fuel source of air.
On the humourous side, if this tech ever get added to cars, then calling the older ones "rust buckets" might be appropriate in a whole new way. :)
Tangent: this again reminds me of the surprising number of breweries or beers called "Bavaria" which are not in fact located in Bavaria. But I guess Bavaria should take that as a compliment...
Very cool stuff, regardless of how it turns out.<p>It claims 'good' energy density and 40% roundtrip efficiency.<p>How does its energy density compare to existing liquid fuels?<p>Naturally, I'm wondering what an iron powder fueled internal combustion engine would look like!
This technology is based on the research from McGill’s Alternative Fuels Laboratory [1]. There are three stages involved: 1. excess electricity is used to make the initial powdered metal, 2. powdered metal burners replace coal or gas burners in existing or new power plants, and 3. excess electricity is used to recycle the powdered metal oxide output from stage 2 back into combustible metal powder.<p>The research is focused on the efficiency and CO2 footprint of all three stages.<p>[1] <a href="http://afl.mcgill.ca/" rel="nofollow">http://afl.mcgill.ca/</a>
"That rust can be regenerated straight back into iron powder with the application of electricity, and if you do this using solar, wind or other zero-carbon power generation systems, you end up with a totally carbon-free cycle."<p>Making solar panels is not carbon free. Making batteries instead of emitting gases is not carbon free. We still have to recycle those panels and those batteries and take in account the impact of it.<p>I feel like we are changing the place where gases are emitted or residues stored instead of making less cars, consuming less in general, etc.
This is the perfect solution for an off grid heat source that wouldn't fatigue electrochemical batteries with limited lifetimes I'd rather reserve for smaller, precise loads (not heating element voltage).<p>I've been saving 1lb propane containers because I thought I would experiment with low pressure (for safety) hydrogen storage as flame source. Then I see videos where people are putting on spark arrestors and using more involving methods to totally remove oxygen (electrically interactive element in a steel container - an amount as low as 4% mixed with hydrogens low ignition point could be hazardous). Combine this with all the hoses and couplings I'd have to put in and it could add up and get complicated (although Alex Lab is a neat channel for hydrogen experimentation).<p>Could I just put a grinder wheel to some pig iron and create a powder stock (high surface area)? Since the powder flows it could be delivered like a wood pellet stove with auto-feed and hopper storage, and maybe for cooking I could spoon feed powder into a bowl with air flow rate control for temperature adjustment? Then another batch would "charge" as a short between two electrodes of a voltage source. Would the constant voltage of a charge controller be necessary for this redox? Could it just be a container of oxidized iron that reacts as voltage is available?
Iron powder burned cleanly producing iron oxide, then reformed into iron powder with electricity. Effectively a battery with combustion as the output.<p>> <i>"the idea certainly seems to have some advantages over hydrogen, pumped hydro, batteries or kinetic energy storage"</i><p>What advantages though? If the process needs combustion then it's interesting but if the combustion is just used generate electricity then how is this better than the other methods?
Related technology might be an end-run around the bad economics of carbon capture systems<p><a href="https://en.wikipedia.org/wiki/Chemical_looping_combustion" rel="nofollow">https://en.wikipedia.org/wiki/Chemical_looping_combustion</a><p>e.g. the CO2 product stream might be clean enough to dispose of without putting it through an acid gas scrubber.
Another article mentions the fuel gets heaver as it burns. So if it was used in a ship it'll get lower in the voyage as you travel.<p>Personally I'm waiting for thunderf00t on this one. (But it's also cool to do strange stuff to brew beer, the story is an important part of the drinking, allegedly)
> High-efficiency electrolysis of iron oxide can store as much as 80 percent of your input energy in the iron fuel<p>Looks promising for home heating during the winter; especially promising for areas of the world where the winter day is so short that using solar + battery for heating is impractical.<p>> Using this kind of cyclical process to generate electricity could approach a theoretical efficiency around 40 percent<p>My heat pump (air based) has a COE of 2.7. If the electricity was stored at 40% efficiency, that means I'm getting back 108% of the energy if combusting iron is used to store the energy!<p>Note: Where I live we have an old oil plant that only runs during cold snaps; and a newer gas plant next to it that runs when renewables are scarce.
Also proposed for silicon: <a href="http://earth.waikato.ac.nz/staff/bardsley/download/silicon_economy.pdf" rel="nofollow">http://earth.waikato.ac.nz/staff/bardsley/download/silicon_e...</a>
But what about the energy needed & carbon dioxide released in the mining and refining of that iron ore to this usable iron powder?<p>Also , that electrolysis would surely leave behind some nasty acids and what not. What about their dumping ?
The nice thing in this process of the oxidation of the metal, it is done with hydrogen and does not involve any emission of CO2. Effectively what they do is:<p>Electricity from renewables -> Hydrogen (electrolysis) -> (iron oxide to iron, in loop) -> heat -> iron oxide.<p>I would say this is a nice solution to the problem of storing hydrogen.<p>EDIT:
Source, the publication: <a href="https://www.sciencedirect.com/science/article/pii/S0360128518300327" rel="nofollow">https://www.sciencedirect.com/science/article/pii/S036012851...</a>
This iron originally took considerable energy to turn it from rust into iron, when it's burned it becomes rust again.<p>Presumably, this will be useful on a small scale to absorb certain types of scrap iron and steel that is contaminated with other elements that would make it unsuitable for normal recycling.<p>High quality iron would be better off being recycled, as the huge amount of energy originally expended in its reduction from oxide to iron doesn't have to be expended on the production of new iron.
Let me get this straight. The theory is you use some other means to heat up the iron to its burning point (probably by burning fuel, unless electricity can be used to bring material >1000 C?). Then you can turn off the energy input because the fuel is burning, at which point it will oxidize on its own...? I'm not really sure I'm grasping how this is an efficient system
For those interested in the history of chemistry:<p>These are the types of experiments that led to the discovery of oxygen.<p>Highly recommend this documentary funded by the NSF: <a href="https://youtu.be/z3Gt5IOjAu" rel="nofollow">https://youtu.be/z3Gt5IOjAu</a><p>Even my 4th grader liked it.
It seems like they've made a battery that only ballasts heat, with a material that is tricky to move around and has a complex mechanical cycle. It will be interesting to see what the eroi is on this vs. lithium ion, pumped storage, or even old school boiler heat ballast.
Can someone explain the process behind burning iron and it being carbon free? How does that work? Don't you need something combustible to keep the process going? I mean, I have rusty iron at home, but holding a match to it doesn't set it alight.
Why does a brewery need a combustion heat source? Is this just for climate control? Or for sanitizing with boiling water?<p>Seems like you could add water to the iron powder to get the exothermic rust reaction as well, if you don't need higher temperatures.
Why not heat molten salt directly? Insulation can be effectively 100% (silvered vacuum bottle) and molten salt through a heat exchanger will boil water pretty fast and heat can be pumped into the salt with at least 100% efficiency.
Video from the team 3years ago: <a href="https://www.youtube.com/watch?v=tVKBNfjL20c&feature=youtu.be&t=15" rel="nofollow">https://www.youtube.com/watch?v=tVKBNfjL20c&feature=youtu.be...</a>
That's pretty cool.<p>Wonder if this can be used for heating homes via small rechargeable cells that one recharges during summer with nothing more than a magnifying glass (well, or a concentrated solar plant).<p>I guess that's almost same as wood, except safer.
I don't know how this would scale. Like, you can't deliver iron filings/powder efficiently via pipes, can you? Certainly not via existing infrastructure. Clogs would probably be certain.
The chemical equation for rust is:
4Fe + 3O2 + 6H2O → 4Fe(OH)3<p>Where does the hydrogen come from when burning the iron powder since (presumably) water is not part of the burning process?
What I'm reading is that there is hope for the return of steam trains, and they will be carbon neutral this time.<p>Honestly haven't been this excited by energy for years.
This is probably a terrible idea:<p>"Our ambition is to convert the first coal-fired power plants into sustainable iron fuel plants by 2030.”<p>They make it sound so clean with the ability to recover and reuse the iron. But if you replace coal with iron you'll need more than one coal fired plant to produce the energy to recover the burned iron. You can use wind or solar to power the electrolysis instead, but then theres no need to bother with the iron at all.<p>I bet they're hoping to just sequester the rust in a landfill or something.
I have to think that if this form of energy was practical, humanity would have gravitated towards using it in the 3200 years since the start of the Iron Age.<p>Iron needs to be mined, transported, ground and then the rust recycled somehow. Is the value of the energy released substantially more than the aggregate costs of releasing it?
dude is pouring powdered iron couple feet from his face with no mask on<p>sure hope he's not accidentally inhaling any of those fine particles bouncing off the funnel
The article says that iron burns at up to 1800 C. I found a short list of other fuels:<p><a href="https://toolsowner.com/blacksmith-forge-temperature" rel="nofollow">https://toolsowner.com/blacksmith-forge-temperature</a><p>And we can use the Carnot formula to calculate efficiency:<p><a href="https://en.wikipedia.org/wiki/Carnot%27s_theorem_(thermodynamics)" rel="nofollow">https://en.wikipedia.org/wiki/Carnot%27s_theorem_(thermodyna...</a><p>efficiency = 1 - T_cold/T_hot = (T_hot - T_cold)/T_hot<p>First we must convert to Kelvin by adding 273.15 to the Celsius temperature. Here is a table with Carnot efficiencies calculated, assuming that the cool end of the cycle is something like a car radiator at just below the boiling point of water at 373 K (100 C or 212 F):<p>Material Temperature(Kelvin) Efficiency:<p>---<p>Coal 2250 83%<p>Iron 2073 82%<p>Propane 1533 76%<p>Wood 893 58%<p>Im having a hard time finding efficiencies for iron oxide electrolysis because all of the papers are behind paywalls. A big portion of the energy required is in heating the iron oxide in the first place, which could be done easily by solar collectors for free:<p><a href="https://newenergyandfuel.com/http:/newenergyandfuel/com/2010/08/31/use-sunlight-to-smelt-iron-ore/" rel="nofollow">https://newenergyandfuel.com/http:/newenergyandfuel/com/2010...</a><p>This claims about 85-96% efficiency for aluminum oxide electrolysis:<p><a href="https://www.tms.org/pubs/journals/JOM/9905/Welch-9905.html" rel="nofollow">https://www.tms.org/pubs/journals/JOM/9905/Welch-9905.html</a><p>I think a 95% efficiency might be reasonable for iron oxide if the temperature is raised by free solar thermal energy. So round trip efficiency is:<p>efficiency = 0.95 * 0.82 = 78%<p>This could be raised by a few percent by using a colder radiator (closer to room temperature at 300 K) and recapturing some of the waste heat with a Stirling engine. So I think that the article is accurate.<p>If someone has a table of electrolysis efficiencies for various compounds, that would be helpful.<p>Edit: after thinking about this for a moment, I realized that the Carnot efficiency should be calculated against room temperature if only the heat is being used and we aren't generating electricity. It only increases the efficiencies in the table above by about 3-8% from hottest to coldest, respectively.<p>Edit 2: for anyone curious, capturing heat and converting it to electricity is usually about 70% efficient at a turbine, and 95% efficient at a generator, for about 65% total. That's why a jet engine is limited to about 0.80 * 0.70 * 0.95 = 55% efficiency (40% in practice). Stirling engines are much closer to their ideal Carnot efficiency because their losses to turbulence (friction/entropy) are much lower. If my numbers are a little off here, please correct me.
Isn't this basically how those single-use hand warmers work? Fine iron powder reacts with air/moisture?<p>Sounds pretty useless given that a) Elemental iron does not occur naturally on earth b) It requires a lot of energy, usually fossil fuels to make it.