Iron fuel shows its mettle • Hacker News Board

Re: Iron fuel shows its mettle

#61

Post by jerf » Fri, Jun 23, 2023, 3:56 PM UTC

obblekk wrote: post #14

> 0.3% of the Iron-oxide becomes nanoparticles which cannot be converted back into Iron. At that rate, 50% of the initial iron will be gone in 333 cycles of iron -> iron oxide -> iron. This a hard type of energy source to reason about: 1. It's not a pure fuel and acts like a battery most of the time, but it's also not renewable 2. Iron is extremely abundant on Earth, but it requires mining and processing to extract 3…

To a first approximation, Earth is a big ball of iron, so losing 50% of the iron in 333 cycles doesn't seem like that big a deal. Getting more iron is an energy issue rather than an availability issue.

I'm also somewhat concerned about the nanoparticle's effect on living things. It is likely that it is only a question of local exposure, as in general once they get out they should still rust in some relatively short period of time, and as Earth is the aforementioned big ball of iron, a bit of rust in the environment is quite unlikely to hurt anything because if it could hurt a thing that thing would already be dead, but locally nanoparticles would be something weird and I could see breathing them could be problematic. It is also entirely possible that it is safe up to surprisingly absurd levels too (your body is familiar with iron, and while there are toxic doses of iron you're not getting to them with nanoparticle exposure any time soon), it would just be something that would need some study.

Re: Iron fuel shows its mettle

#62

Post by hn_throwaway_99 » Fri, Jun 23, 2023, 3:59 PM UTC

balaga01 wrote: post #29

intothemild wrote: post #16

Earlier quoted context omitted.

Sure you could use renewables to make iron. But that thought process also extends to other methods too. You could use renewables to make other non renewable fuels. Why not just skip the middleman? Use renewables?

Well, it ties into the storage issue that we see with renewable. We still need energy when there is no wind at night. Burning iron at night and regenerating during the day could be a solution. It needs to prove that it can be competitive with the other methods (compressed air, li-ion batteries, flow batteries, molten salts, flywheels...).

> It needs to prove that it can be competitive with the other methods.

I think the one thing is that iron storage would be a potential long term form of storage, while all those other methods that you mentioned are really short term, designed primarily just to deal with the daily peaks and troughs of renewable production, but not as much the "it's been completely overcast for 3 weeks" problem. The only other form of storage I'm aware of that is also long term like that is pumped water storage, and that is obviously very geographically limited.

Re: Iron fuel shows its mettle

#63

Post by jjk166 » Fri, Jun 23, 2023, 4:00 PM UTC

obblekk wrote: post #14

> 0.3% of the Iron-oxide becomes nanoparticles which cannot be converted back into Iron. At that rate, 50% of the initial iron will be gone in 333 cycles of iron -> iron oxide -> iron. This a hard type of energy source to reason about: 1. It's not a pure fuel and acts like a battery most of the time, but it's also not renewable 2. Iron is extremely abundant on Earth, but it requires mining and processing to extract 3…

The nanoparticles can't be converted back to iron in this process, but they can still be turned back into iron by other processes. No system is truly closed loop, but this is more closed loop than any other energy-to-fuel system.

You need to extract the feedstocks for any energy-to-fuel system. Iron is cheap and simple to extract, compared to say carbon from the atmosphere.

The nanoparticles do not get released to the environment. Emissions from burning carbon based fuels also include pollutants that are hazardous to human health.

Re: Iron fuel shows its mettle

#64

Post by chasil » Fri, Jun 23, 2023, 4:06 PM UTC

Tade0 wrote: post #50

> “Places that have excess energy could make iron, and others can buy it. This way, you could commodify renewable energy so it can be globally distributed without the need for transmission lines. Metals can solve a big problem in the renewable energy transition: long-duration energy storage.” My gut feeling is that transmission lines would still be cheaper. That being said long-term storage seems to be the value prop…

"Altiro gets around this problem by adding a little natural gas to ignite the iron powder when the boiler first starts up."

You will also need a very specialized furnace, and supplies of CH4.

Re: Iron fuel shows its mettle

#65

Post by DontchaKnowit » Fri, Jun 23, 2023, 4:07 PM UTC

upofadown wrote: post #43

ermir wrote: post #6

Iron is not widely available in nature as a ready-to-use element, it must be processed into elemental iron, which takes a lot of energy as input. Therefore this can't be really considered as fuel, more like energy storage. You still need fossil fuels or nuclear power to turn iron ores into iron, then you have iron available for the process described in the article. I'm not criticizing the process, but it's not accura…

The definition of the word "fuel" does not include the requirement that it was originally found laying around in the environment.

Yeah but it pretty much requires that producing the fuel requires less energy than the fuel provides, otherwise itd be like trading a quarter for a dime.

Re: Iron fuel shows its mettle

#66

Post by SamPatt » Fri, Jun 23, 2023, 4:10 PM UTC

Requiring natural gas to work makes me a bit skeptical. They don't indicate how significant the nat gas component is, but if prices are low, it will be much simpler and cheaper to just use the gas itself.

Re: Iron fuel shows its mettle

#67

Post by idiotsecant » Fri, Jun 23, 2023, 4:11 PM UTC

jjk166 wrote: post #63

obblekk wrote: post #14

> 0.3% of the Iron-oxide becomes nanoparticles which cannot be converted back into Iron. At that rate, 50% of the initial iron will be gone in 333 cycles of iron -> iron oxide -> iron. This a hard type of energy source to reason about: 1. It's not a pure fuel and acts like a battery most of the time, but it's also not renewable 2. Iron is extremely abundant on Earth, but it requires mining and processing to extract 3…

The nanoparticles can't be converted back to iron in this process, but they can still be turned back into iron by other processes. No system is truly closed loop, but this is more closed loop than any other energy-to-fuel system. You need to extract the feedstocks for any energy-to-fuel system. Iron is cheap and simple to extract, compared to say carbon from the atmosphere. The nanoparticles do not get released to th…

> Emissions from burning carbon based fuels also include pollutants that are hazardous to human health.

Which do get released into the environment in quite large quantities!

Re: Iron fuel shows its mettle

#68

Post by idiotsecant » Fri, Jun 23, 2023, 4:13 PM UTC

proto-n wrote: post #20

obblekk wrote: post #14

> 0.3% of the Iron-oxide becomes nanoparticles which cannot be converted back into Iron. At that rate, 50% of the initial iron will be gone in 333 cycles of iron -> iron oxide -> iron. This a hard type of energy source to reason about: 1. It's not a pure fuel and acts like a battery most of the time, but it's also not renewable 2. Iron is extremely abundant on Earth, but it requires mining and processing to extract 3…

Is iron oxide magnetic in nanoparticle size? Because if it is, then we can probably very efficiently filter it before releasing it into the atmosphere.

Even if it isn't we are very good at filtering materials from exhaust gasses. Something like a wet electrostatic precipitator is probably overkill, but would do the job without having to care about magnetic properties.

Re: Iron fuel shows its mettle

#69

Post by nabla9 » Fri, Jun 23, 2023, 4:19 PM UTC

proto-n wrote: post #20

obblekk wrote: post #14

> 0.3% of the Iron-oxide becomes nanoparticles which cannot be converted back into Iron. At that rate, 50% of the initial iron will be gone in 333 cycles of iron -> iron oxide -> iron. This a hard type of energy source to reason about: 1. It's not a pure fuel and acts like a battery most of the time, but it's also not renewable 2. Iron is extremely abundant on Earth, but it requires mining and processing to extract 3…

Is iron oxide magnetic in nanoparticle size? Because if it is, then we can probably very efficiently filter it before releasing it into the atmosphere.

Traditional methods or their combination: wet scrubber, electrostatic precipitator or bag filters will do the job.

Re: Iron fuel shows its mettle

#70

Post by [deleted] » Fri, Jun 23, 2023, 4:20 PM UTC

Tade0 wrote: post #50

> “Places that have excess energy could make iron, and others can buy it. This way, you could commodify renewable energy so it can be globally distributed without the need for transmission lines. Metals can solve a big problem in the renewable energy transition: long-duration energy storage.” My gut feeling is that transmission lines would still be cheaper. That being said long-term storage seems to be the value prop…

[deleted]