8 ms·

Iron Powder Passes First Industrial Test as Renewable, Carbon Dioxide-Free Fuel

41 points by samizdis 6y ago

hungryforcodes 6y ago
This sounds really dumb. “Let’s just burn an essential structural metal for fuel! What could go wrong?”
- craftkiller 6y ago
  > So what happens to all that rust? This is where things get clever, because the iron isn’t just a fuel that’s consumed— it’s energy storage that can be recharged. And to recharge it, you take all that Fe2O3, strip out the oxygen, and turn it back into Fe, ready to be burned again. It’s not easy to do this, but much of the energy and work that it takes to pry those Os away from the Fes get returned to you when you burn the Fe the next time. The idea is that you can use the same iron over and over again, discharging it and recharging it just like you would a battery.
- theandrewbailey 6y ago
  How so? Iron is the second-most abundant metal on Earth. https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth...
- hobby-coder-guy 6y ago
  What are you smoking?
- dang 6y ago
  "Please don't post shallow dismissals, especially of other people's work. A good critical comment teaches us something." https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
- pluto9 6y ago
  Oil is used in lots of plastics, which are pretty essential structural materials these days. But we still burn it for fuel. And iron is far more abundant. Also, I'm no chemist but I imagine it's a lot easier to strip an oxygen atom or two off of an iron oxide molecule than to string together a bunch of water and atmospheric CO2 molecules into a complex hydrocarbon. So we can convert the combustion byproducts back into fuel much more easily with iron.
  - hungryforcodes 6y ago
    Fair enough, these are all good points.
avmich 6y ago
While we're at it, we can check other elements as potential reversible fuels. Nitrogen? Sulfur? Aluminum? Sodium?.. Is iron optimal?
- gopalv 6y ago
  > we can check other elements as potential reversible fuels In theory, you want an abundant substance which takes up oxygen, produces solid waste, which is easy to clean up, raw material which is stable in outdoor conditions (if spilled) and non-toxic to your skin in either form. I read through the literature after seeing a NewAtlas article a couple of weeks ago [1] & [2]. > Nitrogen? Sulfur? Gases are harder to take to recycling. > Sodium? Can't touch it without gloves or sneeze around it (the problem is H2 gas, not the sodium itself). There was a memorable sodium leak in a Kalpakkam nuclear power plant in India that I remember, where the issue was the H2 from the sodium + water lines breaking. > Aluminum? Aluminium would be easier to mine out of the ground than Fe, but Al02 to Al is a harder conversion to do already in terms of energy efficiency. And as someone who's burned through a crucible and the floor with Thermite & spent time cleaning it up, the real value of iron oxide is that it doesn't get "harder by burning" (AlO2 is HARD) & produces a fragile and flaky waste product which is easy to clean off the equipment. [1] - https://newatlas.com/energy/bavarian-brewery-carbon-free-renewable-iron-fuel/ https://newatlas.com/energy/bavarian-brewery-carbon-free-ren... [2] - https://newatlas.com/mcgill-metal-powder-fuel/40869/ https://newatlas.com/mcgill-metal-powder-fuel/40869/?
  - avmich 6y ago
    You didn't expect me to list the whole periodic table :) . So these particular examples may very well be inconvenient - but is iron optimal for such an approach?
    - gopalv 6y ago
      > but is iron optimal for such an approach? I found the question equally intriguing. This is still an energy storage medium, so think of it like a very energy dense battery rather than a true fuel & today it is produced by burning carbon in coal/coke. That aside, for a solid powder fuel, pretty much yes. That 2nd article lists out why it is most likely the best choice, but to collect everything I read together. 2nd most abundant (Al is more), powder burns into powder oxide which can be separated easily (not corundum glass), production capacity exists across the world (not exotic material), the waste product will dissolve in acidic water (for cleaning), but isn't a "heavy heavy" metal (we can excrete iron through our kidneys), decent flame capacity (magnesium would burn hotter, maybe), very shelf stable, degrades into the final product (it rusts, but then you dump it the same way), won't catch fire by itself (not like the alkali metals or sulfur/phosphorus) Eventually, there's just a few non-carbon elements which even hit a part of those - Al, Si and Fe. And the other two make it one-use only with glassy (literally) oxides.
AtlasBarfed 6y ago
"Although its specific energy is a relatively poor 1.4 kWh/kg, meaning that for a given amount of energy, iron powder will take up a little bit less space than gasoline but it’ll be almost ten times heavier." Sounds like a good candidate for grid storage if it can be reversed somewhat efficiently, the weight isn't as big a deal in grid, especially if it is compact. The high weight could probably be used to store gravitational potential energy as well in hilly areas. However, if we had a crapton of iron, it would probably be better to seed plankton.
nimbius 6y ago
I've said it before and I'll say it again. An iron oxide fire has a ton of energy but none of the designs or tests I've seen so far even remotely attempt to prepare for an accident. Gas? Shut it off. Wood and coal? Water. Oil? Fine water mist or co2. But iron oxide? An out of control fire can burn for days and most fire departments aren't equipped to handle it. The byproduct is a magma that destroys anything it touches and if water contacts an iron fire it will result in an explosion.
- petertodd 6y ago
  An iron oxide fire is not the same as thermite: burning iron still requires oxygen from the atmosphere, like any other fire. Thermite has its own oxidizer built-in. So I suspect a pile of iron dust wouldn't be that much different from any other combustible dust in terms of fire risk. None of the websites I can find mention iron as an example of a metal fire when talking about the dangers of using water on them. Metals like magnesium and lithium yes. But not iron: https://www.isystemsweb.com/metal-fires/ https://www.isystemsweb.com/metal-fires/ This source talks about the use of water firefighting at steel mills. That's not quite the same thing as powdered metal. But still illustrative: https://firesafeworld.com/fire-safety-in-iron-and-steel-industries-code-of-practice/ https://firesafeworld.com/fire-safety-in-iron-and-steel-indu... As you'd expect, water on hot metal will lead to steam explosions. But from the sounds of it, the simplest solution to that problem is keep your distance, and keep putting water on the fire until it overwhelms the heat capacity of the molten metal.
  - yetihehe 6y ago
    > As you'd expect, water on hot metal will lead to steam explosions. Steam explosions which kick up more metal in air. But I think typical firefighting foam would easily help with that, much less water but still deprives fire of oxygen.
    - petertodd 6y ago
      You're quite right. But if the metal isn't chemically reacting with the water - and it doesn't look like molten iron does - that's not that bad. If you asked me to fight such a fire, I'd setup some unmanned nozzles, retreat, turn on the pumps slowly, and just wait it out. Probably will be an expensive total loss. But no-one gets hurt, and the burning iron doesn't itself release particularly toxic fumes, so no long term harm. Not that bad really for an industrial fire.
kdtop 6y ago
The reason we burn fossil fuels is because we can pull the oil out of the ground and utilize the stored energy. This seems like a different situation than is being described with using iron oxide as a sort of "battery", that will have to later be recharged (reduced away from iron oxide). Thus it seems more like a mechanism for utilizing previously stored energy than as a readily available energy source waiting for exploitation.
- craftkiller 6y ago
  With solar's rapidly declining price, its not hard to imagine a near-future where daytime energy is abundant. In such a scenario, materials that come out of the ground with energy and materials that you need to charge-up like this are practically equivalent. Therefore the days of oil's value are numbered as long as we continue to develop fuel-like renewable energy stores like this.
  - herogreen 6y ago
    But would solar price be the same if the world global energy mix used no fossil fuel ? My belief is no, not at all, unless we used nuclear which can give an energy density similar to fossil fuels. But I have no research data to back this claim.
tasty_freeze 6y ago
One metric that doesn't seem to be mentioned is the efficiency of the process. If 1KWh of usable energy is removed from the fuel, how much energy does it take to reform it back to O2-free iron powder?
kumarvvr 6y ago
Looks like a great idea. Perhaps have a thermal power plant work in tandem with an iron battery system. Say a 20 MW solar plant, works for 6 months to generate powdered iron. Then start the 10 MW companion thermal plant, burn the iron powder instead of coal, generate electricity as a base load plant. Meanwhile the rust ash from the thermal plant is the new fodder for the solar plant. I can see that the overall cyclic efficiency can be lower than existing plants, but definitely carbon neutral.
jjk166 6y ago
It's dumb to call it a fuel - you're recovering the energy that you stored in it during refining. As a battery, a box full of iron has a lot of drawbacks - it has low specific energy (you need a lot of iron to store your energy), it's heavy (it costs a lot to transport from the refinery to the place the energy is being used), and it's inneficient (burning iron to generate steam to drive a turbine might get you 40% efficiency at best, and removing the oxygen again later has its own issues). The one application that this makes sense is for generating process heat - you can slowly store energy by electrolysis and then release it as a very high temperature heat source. In most cases hydrogen would make more sense: it's simpler to electrolyze and burns hotter, but it's difficult to handle and store which might be important for the application.

41 points by samizdis 6y ago

hungryforcodes 6y ago

This sounds really dumb. “Let’s just burn an essential structural metal for fuel! What could go wrong?”

craftkiller 6y ago
> So what happens to all that rust? This is where things get clever, because the iron isn’t just a fuel that’s consumed— it’s energy storage that can be recharged. And to recharge it, you take all that Fe2O3, strip out the oxygen, and turn it back into Fe, ready to be burned again. It’s not easy to do this, but much of the energy and work that it takes to pry those Os away from the Fes get returned to you when you burn the Fe the next time. The idea is that you can use the same iron over and over again, discharging it and recharging it just like you would a battery.
theandrewbailey 6y ago
How so? Iron is the second-most abundant metal on Earth. https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth...
hobby-coder-guy 6y ago
What are you smoking?
dang 6y ago
"Please don't post shallow dismissals, especially of other people's work. A good critical comment teaches us something." https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
pluto9 6y ago
Oil is used in lots of plastics, which are pretty essential structural materials these days. But we still burn it for fuel. And iron is far more abundant. Also, I'm no chemist but I imagine it's a lot easier to strip an oxygen atom or two off of an iron oxide molecule than to string together a bunch of water and atmospheric CO2 molecules into a complex hydrocarbon. So we can convert the combustion byproducts back into fuel much more easily with iron.
- hungryforcodes 6y ago
  Fair enough, these are all good points.

avmich 6y ago

While we're at it, we can check other elements as potential reversible fuels. Nitrogen? Sulfur? Aluminum? Sodium?.. Is iron optimal?

gopalv 6y ago
> we can check other elements as potential reversible fuels In theory, you want an abundant substance which takes up oxygen, produces solid waste, which is easy to clean up, raw material which is stable in outdoor conditions (if spilled) and non-toxic to your skin in either form. I read through the literature after seeing a NewAtlas article a couple of weeks ago [1] & [2]. > Nitrogen? Sulfur? Gases are harder to take to recycling. > Sodium? Can't touch it without gloves or sneeze around it (the problem is H2 gas, not the sodium itself). There was a memorable sodium leak in a Kalpakkam nuclear power plant in India that I remember, where the issue was the H2 from the sodium + water lines breaking. > Aluminum? Aluminium would be easier to mine out of the ground than Fe, but Al02 to Al is a harder conversion to do already in terms of energy efficiency. And as someone who's burned through a crucible and the floor with Thermite & spent time cleaning it up, the real value of iron oxide is that it doesn't get "harder by burning" (AlO2 is HARD) & produces a fragile and flaky waste product which is easy to clean off the equipment. [1] - https://newatlas.com/energy/bavarian-brewery-carbon-free-renewable-iron-fuel/ https://newatlas.com/energy/bavarian-brewery-carbon-free-ren... [2] - https://newatlas.com/mcgill-metal-powder-fuel/40869/ https://newatlas.com/mcgill-metal-powder-fuel/40869/?
- avmich 6y ago
  You didn't expect me to list the whole periodic table :) . So these particular examples may very well be inconvenient - but is iron optimal for such an approach?
  - gopalv 6y ago
    > but is iron optimal for such an approach? I found the question equally intriguing. This is still an energy storage medium, so think of it like a very energy dense battery rather than a true fuel & today it is produced by burning carbon in coal/coke. That aside, for a solid powder fuel, pretty much yes. That 2nd article lists out why it is most likely the best choice, but to collect everything I read together. 2nd most abundant (Al is more), powder burns into powder oxide which can be separated easily (not corundum glass), production capacity exists across the world (not exotic material), the waste product will dissolve in acidic water (for cleaning), but isn't a "heavy heavy" metal (we can excrete iron through our kidneys), decent flame capacity (magnesium would burn hotter, maybe), very shelf stable, degrades into the final product (it rusts, but then you dump it the same way), won't catch fire by itself (not like the alkali metals or sulfur/phosphorus) Eventually, there's just a few non-carbon elements which even hit a part of those - Al, Si and Fe. And the other two make it one-use only with glassy (literally) oxides.

AtlasBarfed 6y ago

"Although its specific energy is a relatively poor 1.4 kWh/kg, meaning that for a given amount of energy, iron powder will take up a little bit less space than gasoline but it’ll be almost ten times heavier." Sounds like a good candidate for grid storage if it can be reversed somewhat efficiently, the weight isn't as big a deal in grid, especially if it is compact. The high weight could probably be used to store gravitational potential energy as well in hilly areas. However, if we had a crapton of iron, it would probably be better to seed plankton.

nimbius 6y ago

I've said it before and I'll say it again. An iron oxide fire has a ton of energy but none of the designs or tests I've seen so far even remotely attempt to prepare for an accident. Gas? Shut it off. Wood and coal? Water. Oil? Fine water mist or co2. But iron oxide? An out of control fire can burn for days and most fire departments aren't equipped to handle it. The byproduct is a magma that destroys anything it touches and if water contacts an iron fire it will result in an explosion.

petertodd 6y ago
An iron oxide fire is not the same as thermite: burning iron still requires oxygen from the atmosphere, like any other fire. Thermite has its own oxidizer built-in. So I suspect a pile of iron dust wouldn't be that much different from any other combustible dust in terms of fire risk. None of the websites I can find mention iron as an example of a metal fire when talking about the dangers of using water on them. Metals like magnesium and lithium yes. But not iron: https://www.isystemsweb.com/metal-fires/ https://www.isystemsweb.com/metal-fires/ This source talks about the use of water firefighting at steel mills. That's not quite the same thing as powdered metal. But still illustrative: https://firesafeworld.com/fire-safety-in-iron-and-steel-industries-code-of-practice/ https://firesafeworld.com/fire-safety-in-iron-and-steel-indu... As you'd expect, water on hot metal will lead to steam explosions. But from the sounds of it, the simplest solution to that problem is keep your distance, and keep putting water on the fire until it overwhelms the heat capacity of the molten metal.
- yetihehe 6y ago
  > As you'd expect, water on hot metal will lead to steam explosions. Steam explosions which kick up more metal in air. But I think typical firefighting foam would easily help with that, much less water but still deprives fire of oxygen.
  - petertodd 6y ago
    You're quite right. But if the metal isn't chemically reacting with the water - and it doesn't look like molten iron does - that's not that bad. If you asked me to fight such a fire, I'd setup some unmanned nozzles, retreat, turn on the pumps slowly, and just wait it out. Probably will be an expensive total loss. But no-one gets hurt, and the burning iron doesn't itself release particularly toxic fumes, so no long term harm. Not that bad really for an industrial fire.

kdtop 6y ago

The reason we burn fossil fuels is because we can pull the oil out of the ground and utilize the stored energy. This seems like a different situation than is being described with using iron oxide as a sort of "battery", that will have to later be recharged (reduced away from iron oxide). Thus it seems more like a mechanism for utilizing previously stored energy than as a readily available energy source waiting for exploitation.

craftkiller 6y ago
With solar's rapidly declining price, its not hard to imagine a near-future where daytime energy is abundant. In such a scenario, materials that come out of the ground with energy and materials that you need to charge-up like this are practically equivalent. Therefore the days of oil's value are numbered as long as we continue to develop fuel-like renewable energy stores like this.
- herogreen 6y ago
  But would solar price be the same if the world global energy mix used no fossil fuel ? My belief is no, not at all, unless we used nuclear which can give an energy density similar to fossil fuels. But I have no research data to back this claim.

tasty_freeze 6y ago

One metric that doesn't seem to be mentioned is the efficiency of the process. If 1KWh of usable energy is removed from the fuel, how much energy does it take to reform it back to O2-free iron powder?

kumarvvr 6y ago

Looks like a great idea. Perhaps have a thermal power plant work in tandem with an iron battery system. Say a 20 MW solar plant, works for 6 months to generate powdered iron. Then start the 10 MW companion thermal plant, burn the iron powder instead of coal, generate electricity as a base load plant. Meanwhile the rust ash from the thermal plant is the new fodder for the solar plant. I can see that the overall cyclic efficiency can be lower than existing plants, but definitely carbon neutral.

jjk166 6y ago

It's dumb to call it a fuel - you're recovering the energy that you stored in it during refining. As a battery, a box full of iron has a lot of drawbacks - it has low specific energy (you need a lot of iron to store your energy), it's heavy (it costs a lot to transport from the refinery to the place the energy is being used), and it's inneficient (burning iron to generate steam to drive a turbine might get you 40% efficiency at best, and removing the oxygen again later has its own issues). The one application that this makes sense is for generating process heat - you can slowly store energy by electrolysis and then release it as a very high temperature heat source. In most cases hydrogen would make more sense: it's simpler to electrolyze and burns hotter, but it's difficult to handle and store which might be important for the application.