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Dutch brewery burns iron as a clean, recyclable fuel

751 points by bornelsewhere 6y ago

CGamesPlay 6y ago
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?
- bornelsewhere 6y ago
  I suspect the primary point is marketing. But that is fine, new tech needs early adopters to speed up development. For whatever reasons.
- deleted 6y ago
  [deleted]
- nuccy 6y ago
  Iron has a specific energy of 4.9 MJ/kg (for comparison: wood 18, coal 26-33, natural gas 53.6, jet fuel 43, diesel 45.6, gasoline 46.4). So having ships, planes or even cars powered by burning iron seems to be unfeasible (at least from energy production standpoint). Albeit iron has much higher density, so if weight is not a problem then it may work. Iron has energy density of about 40 MJ/liter which is comparable with coal, diesel, petrol, which have ~34-40 MJ/liter.
  - Karliss 6y ago
    That's still 5-10 times higher than lithium based batteries (0.3-1MJ/kg) and those are being used in cars and almost good enough for some airplane use cases. Heat engine efficiency isn't as good as electric motors, but it isn't bellow 20%. Downside is that recharging by converting back to iron probably can't be done within device. While pouring in metal powder in for fast refilling might be doable getting it out is probably messier.
    - BlueTemplar 6y ago
      You would need a steam engine to convert heat into work, which is clearly out of the question for planes, and might make cars and trucks impractical. Maybe rail and boats though ?
    - nuccy 6y ago
      Yes, but even best combustion engines have at very best 50% efficiency using direct transformation of thermal energy through gas expansion into mechanical energy. This involves numerous technologies, which better mix fuel and air, inject fuel directly, adjust timing of injection and exhaust following the RPMs, etc. Cars don't generate steam or use any other indirect method of transformation of thermal energy into mechanical energy, due to losses and impracticality (otherwise we would see other types of combustion engines). Burning of powder iron would not work with normal ICEs since powders are not liquids, they are abrasive and burn residuals are not gaseous (rust dust, which is even more abrasive). At very least this is non trivial engineering challenge. So 5-10 times lower specific energy of lithium batteries wins because of simplicity (and lower weight) of whole power-train (inverters, engines) and their high overall efficiency (90-95%). But indeed, on big ships (e.g. tankers), which can have a steam turbines, iron might be a feasible fuel (especially if using onboard solar power while cruising it is possible to recover part of it as a fuel again).
      - ClumsyPilot 6y ago
        I this is is largely on point - this should work for larger ships that have steam turbines. Also, said turbines have better efficiency than an ICE engine.
        xyzzyz 6y ago
        They don't, actually. Steam turbines are less, not more efficient than marine diesel engines. In modern marine propulsion, turbines are used pretty much only on gas and coal carriers.
      - ncmncm 6y ago
        Ships get well north of 70% efficiency on the same cycle: technically, the Diesel cycle. (It is named after the person, not the fuel.) Most cars run on the Otto cycle, less efficiently. (It is named after the person, not the vehicle.:-)
  - trhway 6y ago
    >So having ships, planes or even cars powered by burning iron seems to be unfeasible aluminum of course. It is cheap too and has higher specific energy than iron. Using aluminum-air fuel cell instead of burning makes the efficiency about 2 times higher. The actual cars powered by aluminum have range up to 2000km per refueling.
  - ClumsyPilot 6y ago
    It us perfectly feasible on ships, they are not restricted on mass very much and their fuel is dirty and not very efficient. Although we could have really fast nuclear powered container ships and the whole problem goes away
- bentpins 6y ago
  One nice thing is that in brewing it can be used to generate heat for boiling during brewing rather than converting to electricity first. They mention a furnace but not a generator. 81% of Dutch power is fossil fuel based, if you have an environmental concern about that and it's good press why not.
- jacobush 6y ago
  Not unique, but the twist is that they need heat, not electricity. I thought it interesting. Edit: Made me day dream about Iceland exporting iron powder for burning, electrolysed with their geothermal energy.
- londons_explore 6y ago
  Iron can be produced from electricity as the article mentions, but most iron today is produced with coal, since its far cheaper. This is just a way for the brewery to get cheap heat, with a level of indirection from the source coal so it can be advertised as green. It's a shame the journalist that did this article didn't think to research how iron is typically made...
  - LarvaFX 6y ago
    Once made and stuffed into this system, the iron can be used in an infite loop of combustion and restore using electricity when it's available.
    - jacobush 6y ago
      The Oxygen too could be in the same infinite loop if there is some kind of storage large enough. (Salt mine?) Then there would be NOx pollutants either.
    - londons_explore 6y ago
      Indeed, but the iron oxide powder resulting from this process would be cheaper to turn back into iron metal using coal in a regular blast furnace.
      - hsuduebc 6y ago
        We'll they are trying to make it green as possible so coal if out of game. At least locally for one device.
- tsar_nikolai 6y ago
  > On a side note, what's the point of a brewery (single business) using it? Do they have some unique energy requirements? It's a collaboration with a local university to test the technique on industrial scale. According to the researchers there the goal is to grow to grid-scale and convert coal-fired power plans in the coming decade.
  - mikro2nd 6y ago
    The brewery is not using the process to generate electricity, but to heat fluids (water and wort). The research team behind it hope to scale it up to electricity generation in the future.
- mikro2nd 6y ago
  As I understood the article, the brewery is not using the process to generate electricity, but to heat fluids (water and wort). In essence brewing process is a hell of a lot about moving heat around: You heat water to mash the grain to make wort, you boil the wort, then you remove the heat (via heat exchanger) as quickly as possible to get the wort down to where the yeast is happy. What are you going to do with all that energy you've pumped in to the fluid in the first place and have just pumped out again? If you're clever (energy conscious) you find a way to cycle that back into the process. There are lots of opportunities to optimise and conserve the energy that gets shunted back and forth in a brewery and it's a whole art/science in itself.
- socialdemocrat 6y ago
  Iron is much durable than a battery. The brewery is like lots of other industrial processes. They need a lot of heath which typically coal produce today. Metal powder can replace coal in all these industrial settings.
bencollier49 6y ago
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.
- pishpash 6y ago
  Not even close. Second law of thermodynamics puts a limit on heat engine. Gravity storage is not subject to such limit. But it is a great idea to burn any fuel whose oxidized product is not a gas. The only reason why burning hydrocarbons is problematic is because carbon dioxide is a gas, otherwise it could be captured and recycled like this.
  - stkdump 6y ago
    Seems about right. Pumped storage is at about 70% efficiency round-trip, this is 40%. Also, not producing greenhouse gases sounds like a good idea.
  - knolax 6y ago
    Well I think in this case the iron is feeding a furnace so it's not going through a heat engine, it's just giving off heat.
    - socialdemocrat 6y ago
      Yes and anyway you could use combined heath and power systems to get higher efficiency.
      - fastball 6y ago
        Not sure I follow.
        hinkley 6y ago
eximius 6y ago
Very cool stuff, regardless of how it turns out. It claims 'good' energy density and 40% roundtrip efficiency. How does its energy density compare to existing liquid fuels? Naturally, I'm wondering what an iron powder fueled internal combustion engine would look like!
- londons_explore 6y ago
  Iron powder probably wouldnt work in an internal combustion engine - wear on engine components would be too high. Instead it works well I. Big open furnaces where you extract the energy via superheated steam.
  - eximius 6y ago
    And it would be difficult to 'aerosolize' the powder injection into the combustion chamber and all sorts of problems. It would take a fundamentally different design. But it's still a fun thought :)
- Tade0 6y ago
  How does its energy density compare to existing liquid fuels? Diesel engines have a thermodynamic efficiency of ~42% in optimal conditions - usually it's less. Large marine units approach 50%, but the fuel they use is only technically liquid. EDIT: I just noticed you were asking about density, not efficiency. I suspect it's much less than liquid fuels, which derive most of their energy from burning the hydrogen in them.
- BlueTemplar 6y ago
  I don't see how an iron powdered internal combustion engine – where the fuel is usually a liquid and the waste is a gas – could possibly work. We do have a lot of experience with steam engines though, but AFAIK they're much harder to miniaturize to be able to fit in a car ?
manigandham 6y ago
Iron powder burned cleanly producing iron oxide, then reformed into iron powder with electricity. Effectively a battery with combustion as the output. > "the idea certainly seems to have some advantages over hydrogen, pumped hydro, batteries or kinetic energy storage" 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?
- tom_mellior 6y ago
  > but if the combustion is just used generate electricity This is where the brewery angle is interesting, since (as others have mentioned as well) what brewing needs is mostly heat for boiling. Combustion gives you heat directly.
- jml7c5 6y ago
  Hydrogen embrittles metal, combusts too readily, and generally must be stored at pressure for transport; pumped hydro requires the right geology/topology; batteries wear out; kinetic energy storage is low-density.
sparsely 6y ago
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.
zaarn 6y ago
Using more ... aggressive metals might help energy density here, though it would require more energy losses during rebuilding the oxides. 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. 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. The only issue is obtaining a shitton of flourine to burn your carbon with and then not blowing yourself up in the process. (Also yes, Flourine will burn CO2 and act as the oxidizer)
- La1n 6y ago
  >Using more ... aggressive metals might help energy density here I think breweries are one of the types of business that could more easily use low density fuels. Right now a lot of the beer is moved by road, and the trucks that transport beer are often empty on their way to a brewery.
  - adwn 6y ago
    > the trucks that transport beer are often empty on their way to a brewery. You have to transport the iron oxide back to where it can be recycled. That's the "advantage" of burning fossil fuels: most of the combustion products are volatile, so you can release them into the atmosphere.
    - jacobush 6y ago
      It could be recycled on site.
      - adwn 6y ago
        Yes, but then there's also no use for the empty trucks en route the brewery.
itcrowd 6y ago
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?
- andor 6y ago
  You're right, NOx emissions are always a side-effect when something is burned in our nitrogen-rich atmosphere. This version of the story mentions that NOx and particulates are something they will have to work on: https://www.deingenieur.nl/artikel/first-system-to-use-iron-powder-as-fuel-has-been-built https://www.deingenieur.nl/artikel/first-system-to-use-iron-...
  - avodonosov 6y ago
    > when something is burned At high temperatures. Burning coal is clean in this sense, as I understand.
    - avodonosov 6y ago
      After this downvoted I've read around and found that coal power plants also contribute to NOx emissions. But higher temperatures seem to be much more dangerous. I've heard that from critiques of hydrogen burning, they said burning pure hydrogen is unacceptable due to high temperature leading to NOx emission. Found this: > It is believed that an increase in the maximum temperature in the combustion zone above 1850 K leads to unacceptably high NOx emissions , and one of the main ways to reduce emissions by the thermal mechanism is to prevent the formation of hot spots in the flame front. https://translate.google.com/translate?hl=&sl=ru&tl=en&u=https%3A%2F%2Fru.wikipedia.org%2Fwiki%2FNOx_(%D0%BE%D0%BA%D1%81%D0%B8%D0%B4%D1%8B_%D0%B0%D0%B7%D0%BE%D1%82%D0%B0) https://translate.google.com/translate?hl=&sl=ru&tl=en&u=htt...
      - ncmncm 6y ago
        If you burn it in pure oxygen, there are no NOx emissions. You can store the oxygen released when you produce iron from powdered rust, and use it to burn the iron later.
tsjq 6y ago
But what about the energy needed & carbon dioxide released in the mining and refining of that iron ore to this usable iron powder? Also , that electrolysis would surely leave behind some nasty acids and what not. What about their dumping ?
- Ensorceled 6y ago
  The iron powder is reusable so this is a one time mining operation. What acids do you think are produced in the electrolysis?
- fghorow 6y ago
  I agree. This process needs a lifecycle analysis, not just a round-trip analysis.
hilbert42 6y ago
This iron originally took considerable energy to turn it from rust into iron, when it's burned it becomes rust again. 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. 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.
- M2Ys4U 6y ago
  I think the point of this is one can use intermittently available renewable sources of power (wind, solar, tidal) to electrolyse the rust to produce the iron powder for on-demand burning. The rust produced by burning can then be re-electrolysed to make more pure iron powder.
justinclift 6y ago
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. :)
aaron695 6y ago
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. 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)
- amelius 6y ago
  A brewery on a ship, what could go wrong?
radu_floricica 6y ago
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. 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". 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).
- ReptileMan 6y ago
  Still an option for the mix if you have to capture a huge surplus of renewables. And there are no metallurgy smelting plants nearby.
- MayeulC 6y ago
  You are right, of course, but I wonder if you couldn't use "waste heat" as the energy input of this "heat battery"? This would make the economics much better: instead of going, say, nuclear -> steam engine -> electricity -> iron -> heat (-> electricity), you could skip the first conversion losses. Not sure how doable it would be from a chemistry point of view, though: you probably need at least one extra reagent or catalyst.
  - abdusco 6y ago
    Source temperature of waste heat is an important factor. Heat radiating from a 2000C source is a lot more valuable & useful than that from some warm water at 60C. You can't use that heat to raise the temperature of something to 61C, for example.
    - 6y ago
rob74 6y ago
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...
- Deukhoofd 6y ago
  Pilsner beer was sometimes called Bavarian Beer in the past. I guess it makes sense for some breweries to adopt the name.
- Fnoord 6y ago
  Look at the URL [1] and indeed, the original title and text was wrong ('Germany') [2]. They left the URL intact. Such blasphemy... (kidding aside, it actually is at least from a journalism standpoint) [1] https://newatlas.com/energy/bavarian-brewery-carbon-free-renewable-iron-fuel/ https://newatlas.com/energy/bavarian-brewery-carbon-free-ren... [2] https://web.archive.org/web/20201104083956/https://newatlas.com/energy/bavarian-brewery-carbon-free-renewable-iron-fuel/ https://web.archive.org/web/20201104083956/https://newatlas....
dzhiurgis 6y ago
That's pretty cool. 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). I guess that's almost same as wood, except safer.
nabla9 6y ago
Not bad. Cyclical efficiency around 40 percent is at the low end of fuel cell efficiency.
pedrocr 6y ago
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.
moneytide1 6y ago
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). 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). 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?
Markxr 6y ago
Isn't this basically how those single-use hand warmers work? Fine iron powder reacts with air/moisture? 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.
- Markxr 6y ago
  Maybe they can cut out the middle-man and just burn coke, which does not need to be stored in a sealed container
  - imtringued 6y ago
    Which middleman? The suggested method of obtaining pure iron powder involves electrolysis of oxidized iron powder. I don't even see where you could insert coke into this process.
    - Markxr 6y ago
      The process for actually making iron, rather than the one they've imagined, involves smelting with coke. I'm pretty sure that electrolysing iron oxide is not a thing that's done on an industrial scale.
- regularfry 6y ago
  Elemental iron does occur naturally in scrapyards, and the process is a cycle.
xchaotic 6y ago
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?
- driverdan 6y ago
  None is wasted. Electrolysis splits the iron and oxygen.
- Pfhreak 6y ago
  Why would iron be wasted? Just like because moving materials around inevitably spills a small amount?
cphoover 6y ago
A thermite boiler... sounds safe
leecarraher 6y ago
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.
bjd2385 6y ago
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.
sradman 6y ago
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. The research is focused on the efficiency and CO2 footprint of all three stages. [1] http://afl.mcgill.ca/ http://afl.mcgill.ca/
- HappyDreamer 6y ago
  Batteries wear out after many charge cycles, I've read -- but what about this "iron powder battery" -- can one use and "re-charge" it "forever"? Or the iron powder "wears out" somehow? less and less oxide can be converted back to iron powder? But then why
  - jacobush 6y ago
    Possibly some of the iron could form iron nitride? But that decomposes at 400 C so it should not matter.
thatcherc 6y ago
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.
- lambdatronics 6y ago
  I think this is what Boston Metal is attempting: https://www.bostonmetal.com/moe-technology/#moe-process https://www.bostonmetal.com/moe-technology/#moe-process
punnerud 6y ago
Video from the team 3years ago: https://www.youtube.com/watch?v=tVKBNfjL20c&feature=youtu.be&t=15 https://www.youtube.com/watch?v=tVKBNfjL20c&feature=youtu.be...
gerardnll 6y ago
"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." 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. 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.
- Craighead 6y ago
  Carbon free cycle, very clearly, means the CYCLE is carbon free, as in no emitted carbon production is happening during the CYCLE You jumped into the deep end really quickly
- adrianN 6y ago
  Consuming less in general is very good, but it's not a strategy that can take you to net zero emissions. Building large amounts of renewables and using excess energy to sequester some carbon on the other hand can become a net zero system.
- blacksqr 6y ago
  One thing to keep in mind is that while commercial and consumer users of electricity generally require steady, high-quality, alternating current, electrolysis can be done with low-quality, intermittent direct current of the sort that can be generated with low-tech electrostatic generators. A whole new parallel infrastructure of low-quality electricity generation could be built without too much effort for electrolysis of iron oxide, powered by low-grade heat and motion sources that currently can't be effectively utilized.
  - ncmncm 6y ago
    Same applies to production of ammonia, which has numerous uses other than fuel--right at the point of production, if that happens to be under a wind turbine placed at the edge of a farmer's field. Waste oxygen is a byproduct of ammonia production from water and air. You really want to use pure oxygen to burn your iron, to avoid producing NOx.
sirffuzzylogik 6y ago
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: Electricity from renewables -> Hydrogen (electrolysis) -> (iron oxide to iron, in loop) -> heat -> iron oxide. I would say this is a nice solution to the problem of storing hydrogen. EDIT: Source, the publication: https://www.sciencedirect.com/science/article/pii/S0360128518300327 https://www.sciencedirect.com/science/article/pii/S036012851...
sycren 6y ago
The chemical equation for rust is: 4Fe + 3O2 + 6H2O → 4Fe(OH)3 Where does the hydrogen come from when burning the iron powder since (presumably) water is not part of the burning process?
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- Retric 6y ago
  Burning Iron is a different process 4Fe + 3 O2 ==> 2 Fe2O3. Critically, rust forms at much lower temperatures.
- yetihehe 6y ago
  Without water, rust is Fe2O3. It's commonly used as red die for cements and cheapest iron oxide. It's also useful with aluminum to make thermite (which generates VERY high temperatures). Long ago I bought some Fe2O3, it was very fine powder and apparently waste from some chemical process. Edit - mistook oxides.
  - sycren 6y ago
    Are there any other useful chemical reactions that can utilise this waste product?
TenebrisNoctis 6y ago
Thats some good news, of course there is always something bad coming with it but i think overall it is good.
stevespang 6y ago
Has anyone questioned the amount of CO2 from coal or coke emitted into the atmosphere to create this pure iron powder ? It carries with it the guilt of those who created the iron in the first place, same as cement.
PaulHoule 6y ago
Related technology might be an end-run around the bad economics of carbon capture systems https://en.wikipedia.org/wiki/Chemical_looping_combustion https://en.wikipedia.org/wiki/Chemical_looping_combustion e.g. the CO2 product stream might be clean enough to dispose of without putting it through an acid gas scrubber.
- jedimastert 6y ago
  > the bad economics of carbon capture systems Can you expand on this?
  - bloaf 6y ago
    Thermodynamically, the higher concentration of CO2 in industrial flue gas means you can capture CO2 there more efficiently than you can from the ambient air. However, industrial carbon capture typically is a loser because processing the huge volumes of gas produced by industrial equipment is neither cheap nor easy, requiring very large & energy intensive facilities. The products produced by such purification aren't valuable enough to offset those costs, and industry will not shoulder that burden out of the goodness of its cold mechanical heart. Chemical looping can reduce the cost of these processing facilities (or eliminate them completely) by dramatically reducing the number of impurities in the CO2 that is produced from combustion, especially nitrogen. I.e. it makes a more pure CO2 product from the get-go, which means the total volume of gas to process is lower, and purification is even easier.
    - PaulHoule 6y ago
      Right, "carbon capture" either from a hydrocarbon stream (carbon neutral) or biomass (carbon negative) competes with many energy sources (solar, wind, nuclear, hydro, conventional fossil fuel combustion) so you'd have to pay operators for the service of stashing CO₂ underground.
  - PaulHoule 6y ago
    Most gas streams from combustion contain a mixture of N₂ and CO₂. CO₂ is disposed of by compressing it 1500 psi and injecting it underground. Even small amounts of N₂ or H₂O will cause the gas to misbehave in the pipeline. The obvious answer to this is https://en.wikipedia.org/wiki/Amine_gas_treating https://en.wikipedia.org/wiki/Amine_gas_treating which is a well-understood process but it is not cheap. The other is to remove the N₂ before combustion. They do this https://en.wikipedia.org/wiki/Rectisol https://en.wikipedia.org/wiki/Rectisol at what used to be the biggest carbon capture plant in the world https://www.dakotagas.com/about-us/gasification/gasification-process https://www.dakotagas.com/about-us/gasification/gasification... but they have a liquid oxygen plant at the head end of the thing and they are separating acid gases from a stream of hydrogen and carbon monoxide about to be built up into methane. There are other methods of combustion with oxygen but they are tricky: temperatures would be high (melt your turbine) if you really used pure oxygen, but if you recycle some of the output gas back into the turbine you might make it work. Of course there is the cost of the oxygen separator so it is hard to be competitive. The hope with CLC is that you might be able to bolt it onto a fluidized bed combustion system and not raise the cost as much as the alternatives.
ck2 6y ago
dude is pouring powdered iron couple feet from his face with no mask on sure hope he's not accidentally inhaling any of those fine particles bouncing off the funnel
gwbas1c 6y ago
> High-efficiency electrolysis of iron oxide can store as much as 80 percent of your input energy in the iron fuel 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. > Using this kind of cyclical process to generate electricity could approach a theoretical efficiency around 40 percent 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! 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.
fuoqi 6y ago
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. 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.
mark4 6y ago
Yet another front-page article about Rust.
zackmorris 6y ago
The article says that iron burns at up to 1800 C. I found a short list of other fuels: https://toolsowner.com/blacksmith-forge-temperature https://toolsowner.com/blacksmith-forge-temperature And we can use the Carnot formula to calculate efficiency: https://en.wikipedia.org/wiki/Carnot%27s_theorem_(thermodynamics) https://en.wikipedia.org/wiki/Carnot%27s_theorem_(thermodyna... efficiency = 1 - T_cold/T_hot = (T_hot - T_cold)/T_hot 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): Material Temperature(Kelvin) Efficiency: --- Coal 2250 83% Iron 2073 82% Propane 1533 76% Wood 893 58% 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: https://newenergyandfuel.com/http:/newenergyandfuel/com/2010/08/31/use-sunlight-to-smelt-iron-ore/ https://newenergyandfuel.com/http:/newenergyandfuel/com/2010... This claims about 85-96% efficiency for aluminum oxide electrolysis: https://www.tms.org/pubs/journals/JOM/9905/Welch-9905.html https://www.tms.org/pubs/journals/JOM/9905/Welch-9905.html 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: efficiency = 0.95 * 0.82 = 78% 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. If someone has a table of electrolysis efficiencies for various compounds, that would be helpful. 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. 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.
hkt 6y ago
What I'm reading is that there is hope for the return of steam trains, and they will be carbon neutral this time. Honestly haven't been this excited by energy for years.
- fastball 6y ago
  Only steam train I want is one powered by fission.
asdfman123 6y ago
Just more evidence that hackernews has a love affair with rust.
deepsun 6y ago
Why don't they just burn electricity, instead of converting it to iron powder first?
gwern 6y ago
Also proposed for silicon: http://earth.waikato.ac.nz/staff/bardsley/download/silicon_economy.pdf http://earth.waikato.ac.nz/staff/bardsley/download/silicon_e...
charliebrownau 6y ago
why dont they use ETHNOL for fuel instead of dug up iron ?
nimbius 6y ago
for those wondering why more applications do not source metal as a fuel, burning metal is frighteningly difficult to extinguish. 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. metal fires also release toxic gasses and byproducts that often require more consideration than electric or gas. as an update to a few questions: NEVER add water to a metal fire. it will cause an explosion. 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. most accidental metal fires do not have a cogent or quick option to deprive the fuel source of air.
- MuffinFlavored 6y ago
  > Metal fires cannot generally be quickly extinguished in an emergency or uncontrolled accident. what happens if you spray a fire extinguisher into a metal fire?
  - Wohlf 6y ago
    At best nothing, at worst you spread the fire around by moving the burning metal.
  - karagenit 6y ago
    Depends on the type of fire extinguisher really. Most extinguishers work to suffocate the fire (e.g. ABC or CO2 extinguishers), but depending on the type of burning metal the chemical(s) in the extinguisher might react with the metal and make the fire worse. They make special "class D" extinguishers specifically for metal fires, which spray a non-reactive powder (usually graphite dust I think) over the metal to suffocate it.
- umvi 6y ago
  > Metal fires cannot generally be quickly extinguished in an emergency or uncontrolled accident In the case of a furnace, couldn't you simply cut off the oxygen supply?
phkahler 6y ago
This is probably a terrible idea: "Our ambition is to convert the first coal-fired power plants into sustainable iron fuel plants by 2030.” 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. I bet they're hoping to just sequester the rust in a landfill or something.
- ianferrel 6y ago
  If solar prices keep trending the way they're trending, then we may have way more solar than we have anything useful to do with during peak sunlight hours in the relatively near future. Using iron as a big chemical battery seems at least plausible. More so if you get to reuse existing infrastructure to turn it back into energy.
- M2Ys4U 6y ago
  Renewable energy sources like wind and solar are intermittent (one can't create electricity using solar at night, or using wind when the air is still, after all), whereas furnaces can, effectively, run whenever there is demand. Electrolysing rust into iron can be done when there is excess renewable energy available, and it can be burned when there is a deficit. In other words, it's a chemical battery.
julienb_sea 6y ago
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
- nathanyukai 6y ago
  doesn't all fuel works like this?
11thEarlOfMar 6y ago
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. 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?
- thinkling 6y ago
  The article discusses using electrolysis with clean energy to recycle the rusted iron dust back to combustible state. This isn't something we've been able (or willing) to do in the past as we didn't have an excess of clean energy.
cwkoss 6y ago
Why does a brewery need a combustion heat source? Is this just for climate control? Or for sanitizing with boiling water? 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.
- chipsa 6y ago
  Brewing generally consists of: Adding your grain to water to form the mash. Cooking the mash to extract the sugars et al. Separating out the mash into the wort and the solids. Boiling the wort. Cooling the wort, then pitching in yeast. Then storing for a while while it ferments. Heating the wort and mash could be done electrically, but generally (especially at brewery scale) is combustion.
LockAndLol 6y ago
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.
benlivengood 6y ago
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.
mensetmanusman 6y ago
For those interested in the history of chemistry: These are the types of experiments that led to the discovery of oxygen. Highly recommend this documentary funded by the NSF: https://youtu.be/z3Gt5IOjAu https://youtu.be/z3Gt5IOjAu Even my 4th grader liked it.

751 points by bornelsewhere 6y ago

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?

bornelsewhere 6y ago
I suspect the primary point is marketing. But that is fine, new tech needs early adopters to speed up development. For whatever reasons.
deleted 6y ago
[deleted]
nuccy 6y ago
Iron has a specific energy of 4.9 MJ/kg (for comparison: wood 18, coal 26-33, natural gas 53.6, jet fuel 43, diesel 45.6, gasoline 46.4). So having ships, planes or even cars powered by burning iron seems to be unfeasible (at least from energy production standpoint). Albeit iron has much higher density, so if weight is not a problem then it may work. Iron has energy density of about 40 MJ/liter which is comparable with coal, diesel, petrol, which have ~34-40 MJ/liter.
- Karliss 6y ago
  That's still 5-10 times higher than lithium based batteries (0.3-1MJ/kg) and those are being used in cars and almost good enough for some airplane use cases. Heat engine efficiency isn't as good as electric motors, but it isn't bellow 20%. Downside is that recharging by converting back to iron probably can't be done within device. While pouring in metal powder in for fast refilling might be doable getting it out is probably messier.
  - BlueTemplar 6y ago
    You would need a steam engine to convert heat into work, which is clearly out of the question for planes, and might make cars and trucks impractical. Maybe rail and boats though ?
  - nuccy 6y ago
    Yes, but even best combustion engines have at very best 50% efficiency using direct transformation of thermal energy through gas expansion into mechanical energy. This involves numerous technologies, which better mix fuel and air, inject fuel directly, adjust timing of injection and exhaust following the RPMs, etc. Cars don't generate steam or use any other indirect method of transformation of thermal energy into mechanical energy, due to losses and impracticality (otherwise we would see other types of combustion engines). Burning of powder iron would not work with normal ICEs since powders are not liquids, they are abrasive and burn residuals are not gaseous (rust dust, which is even more abrasive). At very least this is non trivial engineering challenge. So 5-10 times lower specific energy of lithium batteries wins because of simplicity (and lower weight) of whole power-train (inverters, engines) and their high overall efficiency (90-95%). But indeed, on big ships (e.g. tankers), which can have a steam turbines, iron might be a feasible fuel (especially if using onboard solar power while cruising it is possible to recover part of it as a fuel again).
    - ClumsyPilot 6y ago
      I this is is largely on point - this should work for larger ships that have steam turbines. Also, said turbines have better efficiency than an ICE engine.
      - xyzzyz 6y ago
        They don't, actually. Steam turbines are less, not more efficient than marine diesel engines. In modern marine propulsion, turbines are used pretty much only on gas and coal carriers.
    - ncmncm 6y ago
      Ships get well north of 70% efficiency on the same cycle: technically, the Diesel cycle. (It is named after the person, not the fuel.) Most cars run on the Otto cycle, less efficiently. (It is named after the person, not the vehicle.:-)
- trhway 6y ago
  >So having ships, planes or even cars powered by burning iron seems to be unfeasible aluminum of course. It is cheap too and has higher specific energy than iron. Using aluminum-air fuel cell instead of burning makes the efficiency about 2 times higher. The actual cars powered by aluminum have range up to 2000km per refueling.
- ClumsyPilot 6y ago
  It us perfectly feasible on ships, they are not restricted on mass very much and their fuel is dirty and not very efficient. Although we could have really fast nuclear powered container ships and the whole problem goes away
bentpins 6y ago
One nice thing is that in brewing it can be used to generate heat for boiling during brewing rather than converting to electricity first. They mention a furnace but not a generator. 81% of Dutch power is fossil fuel based, if you have an environmental concern about that and it's good press why not.
jacobush 6y ago
Not unique, but the twist is that they need heat, not electricity. I thought it interesting. Edit: Made me day dream about Iceland exporting iron powder for burning, electrolysed with their geothermal energy.
londons_explore 6y ago
Iron can be produced from electricity as the article mentions, but most iron today is produced with coal, since its far cheaper. This is just a way for the brewery to get cheap heat, with a level of indirection from the source coal so it can be advertised as green. It's a shame the journalist that did this article didn't think to research how iron is typically made...
- LarvaFX 6y ago
  Once made and stuffed into this system, the iron can be used in an infite loop of combustion and restore using electricity when it's available.
  - jacobush 6y ago
    The Oxygen too could be in the same infinite loop if there is some kind of storage large enough. (Salt mine?) Then there would be NOx pollutants either.
  - londons_explore 6y ago
    Indeed, but the iron oxide powder resulting from this process would be cheaper to turn back into iron metal using coal in a regular blast furnace.
    - hsuduebc 6y ago
      We'll they are trying to make it green as possible so coal if out of game. At least locally for one device.
tsar_nikolai 6y ago
> On a side note, what's the point of a brewery (single business) using it? Do they have some unique energy requirements? It's a collaboration with a local university to test the technique on industrial scale. According to the researchers there the goal is to grow to grid-scale and convert coal-fired power plans in the coming decade.
- mikro2nd 6y ago
  The brewery is not using the process to generate electricity, but to heat fluids (water and wort). The research team behind it hope to scale it up to electricity generation in the future.
mikro2nd 6y ago
As I understood the article, the brewery is not using the process to generate electricity, but to heat fluids (water and wort). In essence brewing process is a hell of a lot about moving heat around: You heat water to mash the grain to make wort, you boil the wort, then you remove the heat (via heat exchanger) as quickly as possible to get the wort down to where the yeast is happy. What are you going to do with all that energy you've pumped in to the fluid in the first place and have just pumped out again? If you're clever (energy conscious) you find a way to cycle that back into the process. There are lots of opportunities to optimise and conserve the energy that gets shunted back and forth in a brewery and it's a whole art/science in itself.
socialdemocrat 6y ago
Iron is much durable than a battery. The brewery is like lots of other industrial processes. They need a lot of heath which typically coal produce today. Metal powder can replace coal in all these industrial settings.

bencollier49 6y ago

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.

pishpash 6y ago
Not even close. Second law of thermodynamics puts a limit on heat engine. Gravity storage is not subject to such limit. But it is a great idea to burn any fuel whose oxidized product is not a gas. The only reason why burning hydrocarbons is problematic is because carbon dioxide is a gas, otherwise it could be captured and recycled like this.
- stkdump 6y ago
  Seems about right. Pumped storage is at about 70% efficiency round-trip, this is 40%. Also, not producing greenhouse gases sounds like a good idea.
- knolax 6y ago
  Well I think in this case the iron is feeding a furnace so it's not going through a heat engine, it's just giving off heat.
  - socialdemocrat 6y ago
    Yes and anyway you could use combined heath and power systems to get higher efficiency.
    - fastball 6y ago
      Not sure I follow.
      - hinkley 6y ago

eximius 6y ago

Very cool stuff, regardless of how it turns out. It claims 'good' energy density and 40% roundtrip efficiency. How does its energy density compare to existing liquid fuels? Naturally, I'm wondering what an iron powder fueled internal combustion engine would look like!

londons_explore 6y ago
Iron powder probably wouldnt work in an internal combustion engine - wear on engine components would be too high. Instead it works well I. Big open furnaces where you extract the energy via superheated steam.
- eximius 6y ago
  And it would be difficult to 'aerosolize' the powder injection into the combustion chamber and all sorts of problems. It would take a fundamentally different design. But it's still a fun thought :)
Tade0 6y ago
How does its energy density compare to existing liquid fuels? Diesel engines have a thermodynamic efficiency of ~42% in optimal conditions - usually it's less. Large marine units approach 50%, but the fuel they use is only technically liquid. EDIT: I just noticed you were asking about density, not efficiency. I suspect it's much less than liquid fuels, which derive most of their energy from burning the hydrogen in them.
BlueTemplar 6y ago
I don't see how an iron powdered internal combustion engine – where the fuel is usually a liquid and the waste is a gas – could possibly work. We do have a lot of experience with steam engines though, but AFAIK they're much harder to miniaturize to be able to fit in a car ?

manigandham 6y ago

Iron powder burned cleanly producing iron oxide, then reformed into iron powder with electricity. Effectively a battery with combustion as the output. > "the idea certainly seems to have some advantages over hydrogen, pumped hydro, batteries or kinetic energy storage" 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?

tom_mellior 6y ago
> but if the combustion is just used generate electricity This is where the brewery angle is interesting, since (as others have mentioned as well) what brewing needs is mostly heat for boiling. Combustion gives you heat directly.
jml7c5 6y ago
Hydrogen embrittles metal, combusts too readily, and generally must be stored at pressure for transport; pumped hydro requires the right geology/topology; batteries wear out; kinetic energy storage is low-density.

sparsely 6y ago

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.

zaarn 6y ago

Using more ... aggressive metals might help energy density here, though it would require more energy losses during rebuilding the oxides. 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. 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. The only issue is obtaining a shitton of flourine to burn your carbon with and then not blowing yourself up in the process. (Also yes, Flourine will burn CO2 and act as the oxidizer)

La1n 6y ago
>Using more ... aggressive metals might help energy density here I think breweries are one of the types of business that could more easily use low density fuels. Right now a lot of the beer is moved by road, and the trucks that transport beer are often empty on their way to a brewery.
- adwn 6y ago
  > the trucks that transport beer are often empty on their way to a brewery. You have to transport the iron oxide back to where it can be recycled. That's the "advantage" of burning fossil fuels: most of the combustion products are volatile, so you can release them into the atmosphere.
  - jacobush 6y ago
    It could be recycled on site.
    - adwn 6y ago
      Yes, but then there's also no use for the empty trucks en route the brewery.

itcrowd 6y ago

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?

andor 6y ago
You're right, NOx emissions are always a side-effect when something is burned in our nitrogen-rich atmosphere. This version of the story mentions that NOx and particulates are something they will have to work on: https://www.deingenieur.nl/artikel/first-system-to-use-iron-powder-as-fuel-has-been-built https://www.deingenieur.nl/artikel/first-system-to-use-iron-...
- avodonosov 6y ago
  > when something is burned At high temperatures. Burning coal is clean in this sense, as I understand.
  - avodonosov 6y ago
    After this downvoted I've read around and found that coal power plants also contribute to NOx emissions. But higher temperatures seem to be much more dangerous. I've heard that from critiques of hydrogen burning, they said burning pure hydrogen is unacceptable due to high temperature leading to NOx emission. Found this: > It is believed that an increase in the maximum temperature in the combustion zone above 1850 K leads to unacceptably high NOx emissions , and one of the main ways to reduce emissions by the thermal mechanism is to prevent the formation of hot spots in the flame front. https://translate.google.com/translate?hl=&sl=ru&tl=en&u=https%3A%2F%2Fru.wikipedia.org%2Fwiki%2FNOx_(%D0%BE%D0%BA%D1%81%D0%B8%D0%B4%D1%8B_%D0%B0%D0%B7%D0%BE%D1%82%D0%B0) https://translate.google.com/translate?hl=&sl=ru&tl=en&u=htt...
    - ncmncm 6y ago
      If you burn it in pure oxygen, there are no NOx emissions. You can store the oxygen released when you produce iron from powdered rust, and use it to burn the iron later.

tsjq 6y ago

But what about the energy needed & carbon dioxide released in the mining and refining of that iron ore to this usable iron powder? Also , that electrolysis would surely leave behind some nasty acids and what not. What about their dumping ?

Ensorceled 6y ago
The iron powder is reusable so this is a one time mining operation. What acids do you think are produced in the electrolysis?
fghorow 6y ago
I agree. This process needs a lifecycle analysis, not just a round-trip analysis.

hilbert42 6y ago

This iron originally took considerable energy to turn it from rust into iron, when it's burned it becomes rust again. 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. 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.

M2Ys4U 6y ago
I think the point of this is one can use intermittently available renewable sources of power (wind, solar, tidal) to electrolyse the rust to produce the iron powder for on-demand burning. The rust produced by burning can then be re-electrolysed to make more pure iron powder.

justinclift 6y ago

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. :)

aaron695 6y ago

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. 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)

amelius 6y ago
A brewery on a ship, what could go wrong?

radu_floricica 6y ago

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. 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". 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).

ReptileMan 6y ago
Still an option for the mix if you have to capture a huge surplus of renewables. And there are no metallurgy smelting plants nearby.
MayeulC 6y ago
You are right, of course, but I wonder if you couldn't use "waste heat" as the energy input of this "heat battery"? This would make the economics much better: instead of going, say, nuclear -> steam engine -> electricity -> iron -> heat (-> electricity), you could skip the first conversion losses. Not sure how doable it would be from a chemistry point of view, though: you probably need at least one extra reagent or catalyst.
- abdusco 6y ago
  Source temperature of waste heat is an important factor. Heat radiating from a 2000C source is a lot more valuable & useful than that from some warm water at 60C. You can't use that heat to raise the temperature of something to 61C, for example.
  - 6y ago

rob74 6y ago

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...

Deukhoofd 6y ago
Pilsner beer was sometimes called Bavarian Beer in the past. I guess it makes sense for some breweries to adopt the name.
Fnoord 6y ago
Look at the URL [1] and indeed, the original title and text was wrong ('Germany') [2]. They left the URL intact. Such blasphemy... (kidding aside, it actually is at least from a journalism standpoint) [1] https://newatlas.com/energy/bavarian-brewery-carbon-free-renewable-iron-fuel/ https://newatlas.com/energy/bavarian-brewery-carbon-free-ren... [2] https://web.archive.org/web/20201104083956/https://newatlas.com/energy/bavarian-brewery-carbon-free-renewable-iron-fuel/ https://web.archive.org/web/20201104083956/https://newatlas....

dzhiurgis 6y ago

That's pretty cool. 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). I guess that's almost same as wood, except safer.

nabla9 6y ago

Not bad. Cyclical efficiency around 40 percent is at the low end of fuel cell efficiency.

pedrocr 6y ago

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.

moneytide1 6y ago

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). 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). 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?

Markxr 6y ago

Isn't this basically how those single-use hand warmers work? Fine iron powder reacts with air/moisture? 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.

Markxr 6y ago
Maybe they can cut out the middle-man and just burn coke, which does not need to be stored in a sealed container
- imtringued 6y ago
  Which middleman? The suggested method of obtaining pure iron powder involves electrolysis of oxidized iron powder. I don't even see where you could insert coke into this process.
  - Markxr 6y ago
    The process for actually making iron, rather than the one they've imagined, involves smelting with coke. I'm pretty sure that electrolysing iron oxide is not a thing that's done on an industrial scale.
regularfry 6y ago
Elemental iron does occur naturally in scrapyards, and the process is a cycle.

xchaotic 6y ago

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?

driverdan 6y ago
None is wasted. Electrolysis splits the iron and oxygen.
Pfhreak 6y ago
Why would iron be wasted? Just like because moving materials around inevitably spills a small amount?

cphoover 6y ago

A thermite boiler... sounds safe

leecarraher 6y ago

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.

bjd2385 6y ago

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.

sradman 6y ago

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. The research is focused on the efficiency and CO2 footprint of all three stages. [1] http://afl.mcgill.ca/ http://afl.mcgill.ca/

HappyDreamer 6y ago
Batteries wear out after many charge cycles, I've read -- but what about this "iron powder battery" -- can one use and "re-charge" it "forever"? Or the iron powder "wears out" somehow? less and less oxide can be converted back to iron powder? But then why
- jacobush 6y ago
  Possibly some of the iron could form iron nitride? But that decomposes at 400 C so it should not matter.

thatcherc 6y ago

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.

lambdatronics 6y ago
I think this is what Boston Metal is attempting: https://www.bostonmetal.com/moe-technology/#moe-process https://www.bostonmetal.com/moe-technology/#moe-process

punnerud 6y ago

Video from the team 3years ago: https://www.youtube.com/watch?v=tVKBNfjL20c&feature=youtu.be&t=15 https://www.youtube.com/watch?v=tVKBNfjL20c&feature=youtu.be...

gerardnll 6y ago

"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." 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. 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.

Craighead 6y ago
Carbon free cycle, very clearly, means the CYCLE is carbon free, as in no emitted carbon production is happening during the CYCLE You jumped into the deep end really quickly
adrianN 6y ago
Consuming less in general is very good, but it's not a strategy that can take you to net zero emissions. Building large amounts of renewables and using excess energy to sequester some carbon on the other hand can become a net zero system.
blacksqr 6y ago
One thing to keep in mind is that while commercial and consumer users of electricity generally require steady, high-quality, alternating current, electrolysis can be done with low-quality, intermittent direct current of the sort that can be generated with low-tech electrostatic generators. A whole new parallel infrastructure of low-quality electricity generation could be built without too much effort for electrolysis of iron oxide, powered by low-grade heat and motion sources that currently can't be effectively utilized.
- ncmncm 6y ago
  Same applies to production of ammonia, which has numerous uses other than fuel--right at the point of production, if that happens to be under a wind turbine placed at the edge of a farmer's field. Waste oxygen is a byproduct of ammonia production from water and air. You really want to use pure oxygen to burn your iron, to avoid producing NOx.

sirffuzzylogik 6y ago

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: Electricity from renewables -> Hydrogen (electrolysis) -> (iron oxide to iron, in loop) -> heat -> iron oxide. I would say this is a nice solution to the problem of storing hydrogen. EDIT: Source, the publication: https://www.sciencedirect.com/science/article/pii/S0360128518300327 https://www.sciencedirect.com/science/article/pii/S036012851...

sycren 6y ago

The chemical equation for rust is: 4Fe + 3O2 + 6H2O → 4Fe(OH)3 Where does the hydrogen come from when burning the iron powder since (presumably) water is not part of the burning process?

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Retric 6y ago
Burning Iron is a different process 4Fe + 3 O2 ==> 2 Fe2O3. Critically, rust forms at much lower temperatures.
yetihehe 6y ago
Without water, rust is Fe2O3. It's commonly used as red die for cements and cheapest iron oxide. It's also useful with aluminum to make thermite (which generates VERY high temperatures). Long ago I bought some Fe2O3, it was very fine powder and apparently waste from some chemical process. Edit - mistook oxides.
- sycren 6y ago
  Are there any other useful chemical reactions that can utilise this waste product?

TenebrisNoctis 6y ago

Thats some good news, of course there is always something bad coming with it but i think overall it is good.

stevespang 6y ago

Has anyone questioned the amount of CO2 from coal or coke emitted into the atmosphere to create this pure iron powder ? It carries with it the guilt of those who created the iron in the first place, same as cement.

PaulHoule 6y ago

Related technology might be an end-run around the bad economics of carbon capture systems https://en.wikipedia.org/wiki/Chemical_looping_combustion https://en.wikipedia.org/wiki/Chemical_looping_combustion e.g. the CO2 product stream might be clean enough to dispose of without putting it through an acid gas scrubber.

jedimastert 6y ago
> the bad economics of carbon capture systems Can you expand on this?
- bloaf 6y ago
  Thermodynamically, the higher concentration of CO2 in industrial flue gas means you can capture CO2 there more efficiently than you can from the ambient air. However, industrial carbon capture typically is a loser because processing the huge volumes of gas produced by industrial equipment is neither cheap nor easy, requiring very large & energy intensive facilities. The products produced by such purification aren't valuable enough to offset those costs, and industry will not shoulder that burden out of the goodness of its cold mechanical heart. Chemical looping can reduce the cost of these processing facilities (or eliminate them completely) by dramatically reducing the number of impurities in the CO2 that is produced from combustion, especially nitrogen. I.e. it makes a more pure CO2 product from the get-go, which means the total volume of gas to process is lower, and purification is even easier.
  - PaulHoule 6y ago
    Right, "carbon capture" either from a hydrocarbon stream (carbon neutral) or biomass (carbon negative) competes with many energy sources (solar, wind, nuclear, hydro, conventional fossil fuel combustion) so you'd have to pay operators for the service of stashing CO₂ underground.
- PaulHoule 6y ago
  Most gas streams from combustion contain a mixture of N₂ and CO₂. CO₂ is disposed of by compressing it 1500 psi and injecting it underground. Even small amounts of N₂ or H₂O will cause the gas to misbehave in the pipeline. The obvious answer to this is https://en.wikipedia.org/wiki/Amine_gas_treating https://en.wikipedia.org/wiki/Amine_gas_treating which is a well-understood process but it is not cheap. The other is to remove the N₂ before combustion. They do this https://en.wikipedia.org/wiki/Rectisol https://en.wikipedia.org/wiki/Rectisol at what used to be the biggest carbon capture plant in the world https://www.dakotagas.com/about-us/gasification/gasification-process https://www.dakotagas.com/about-us/gasification/gasification... but they have a liquid oxygen plant at the head end of the thing and they are separating acid gases from a stream of hydrogen and carbon monoxide about to be built up into methane. There are other methods of combustion with oxygen but they are tricky: temperatures would be high (melt your turbine) if you really used pure oxygen, but if you recycle some of the output gas back into the turbine you might make it work. Of course there is the cost of the oxygen separator so it is hard to be competitive. The hope with CLC is that you might be able to bolt it onto a fluidized bed combustion system and not raise the cost as much as the alternatives.

ck2 6y ago

dude is pouring powdered iron couple feet from his face with no mask on sure hope he's not accidentally inhaling any of those fine particles bouncing off the funnel

gwbas1c 6y ago

> High-efficiency electrolysis of iron oxide can store as much as 80 percent of your input energy in the iron fuel 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. > Using this kind of cyclical process to generate electricity could approach a theoretical efficiency around 40 percent 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! 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.

fuoqi 6y ago

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. 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.

mark4 6y ago

Yet another front-page article about Rust.

zackmorris 6y ago

The article says that iron burns at up to 1800 C. I found a short list of other fuels: https://toolsowner.com/blacksmith-forge-temperature https://toolsowner.com/blacksmith-forge-temperature And we can use the Carnot formula to calculate efficiency: https://en.wikipedia.org/wiki/Carnot%27s_theorem_(thermodynamics) https://en.wikipedia.org/wiki/Carnot%27s_theorem_(thermodyna... efficiency = 1 - T_cold/T_hot = (T_hot - T_cold)/T_hot 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): Material Temperature(Kelvin) Efficiency: --- Coal 2250 83% Iron 2073 82% Propane 1533 76% Wood 893 58% 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: https://newenergyandfuel.com/http:/newenergyandfuel/com/2010/08/31/use-sunlight-to-smelt-iron-ore/ https://newenergyandfuel.com/http:/newenergyandfuel/com/2010... This claims about 85-96% efficiency for aluminum oxide electrolysis: https://www.tms.org/pubs/journals/JOM/9905/Welch-9905.html https://www.tms.org/pubs/journals/JOM/9905/Welch-9905.html 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: efficiency = 0.95 * 0.82 = 78% 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. If someone has a table of electrolysis efficiencies for various compounds, that would be helpful. 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. 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.

hkt 6y ago

What I'm reading is that there is hope for the return of steam trains, and they will be carbon neutral this time. Honestly haven't been this excited by energy for years.

fastball 6y ago
Only steam train I want is one powered by fission.

asdfman123 6y ago

Just more evidence that hackernews has a love affair with rust.

deepsun 6y ago

Why don't they just burn electricity, instead of converting it to iron powder first?

gwern 6y ago

Also proposed for silicon: http://earth.waikato.ac.nz/staff/bardsley/download/silicon_economy.pdf http://earth.waikato.ac.nz/staff/bardsley/download/silicon_e...

charliebrownau 6y ago

why dont they use ETHNOL for fuel instead of dug up iron ?

nimbius 6y ago

for those wondering why more applications do not source metal as a fuel, burning metal is frighteningly difficult to extinguish. 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. metal fires also release toxic gasses and byproducts that often require more consideration than electric or gas. as an update to a few questions: NEVER add water to a metal fire. it will cause an explosion. 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. most accidental metal fires do not have a cogent or quick option to deprive the fuel source of air.

MuffinFlavored 6y ago
> Metal fires cannot generally be quickly extinguished in an emergency or uncontrolled accident. what happens if you spray a fire extinguisher into a metal fire?
- Wohlf 6y ago
  At best nothing, at worst you spread the fire around by moving the burning metal.
- karagenit 6y ago
  Depends on the type of fire extinguisher really. Most extinguishers work to suffocate the fire (e.g. ABC or CO2 extinguishers), but depending on the type of burning metal the chemical(s) in the extinguisher might react with the metal and make the fire worse. They make special "class D" extinguishers specifically for metal fires, which spray a non-reactive powder (usually graphite dust I think) over the metal to suffocate it.
umvi 6y ago
> Metal fires cannot generally be quickly extinguished in an emergency or uncontrolled accident In the case of a furnace, couldn't you simply cut off the oxygen supply?

phkahler 6y ago

This is probably a terrible idea: "Our ambition is to convert the first coal-fired power plants into sustainable iron fuel plants by 2030.” 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. I bet they're hoping to just sequester the rust in a landfill or something.

ianferrel 6y ago
If solar prices keep trending the way they're trending, then we may have way more solar than we have anything useful to do with during peak sunlight hours in the relatively near future. Using iron as a big chemical battery seems at least plausible. More so if you get to reuse existing infrastructure to turn it back into energy.
M2Ys4U 6y ago
Renewable energy sources like wind and solar are intermittent (one can't create electricity using solar at night, or using wind when the air is still, after all), whereas furnaces can, effectively, run whenever there is demand. Electrolysing rust into iron can be done when there is excess renewable energy available, and it can be burned when there is a deficit. In other words, it's a chemical battery.

julienb_sea 6y ago

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

nathanyukai 6y ago
doesn't all fuel works like this?

11thEarlOfMar 6y ago

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. 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?

thinkling 6y ago
The article discusses using electrolysis with clean energy to recycle the rusted iron dust back to combustible state. This isn't something we've been able (or willing) to do in the past as we didn't have an excess of clean energy.

cwkoss 6y ago

Why does a brewery need a combustion heat source? Is this just for climate control? Or for sanitizing with boiling water? 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.

chipsa 6y ago
Brewing generally consists of: Adding your grain to water to form the mash. Cooking the mash to extract the sugars et al. Separating out the mash into the wort and the solids. Boiling the wort. Cooling the wort, then pitching in yeast. Then storing for a while while it ferments. Heating the wort and mash could be done electrically, but generally (especially at brewery scale) is combustion.

LockAndLol 6y ago

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.

benlivengood 6y ago

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.

mensetmanusman 6y ago

For those interested in the history of chemistry: These are the types of experiments that led to the discovery of oxygen. Highly recommend this documentary funded by the NSF: https://youtu.be/z3Gt5IOjAu https://youtu.be/z3Gt5IOjAu Even my 4th grader liked it.