Iron fuel shows its mettle • Hacker News Board

Re: Iron fuel shows its mettle

#41

Post by a3w » Fri, Jun 23, 2023, 3:42 PM UTC

umvi wrote: post #31

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 are not emitted in the atmosphere but captured in a HEPA filter. If that's true, your point #3 is moot. And if the nano particles can be captured by a filter, maybe we could design filters specifically for iron oxide nano particles that would allow the nano particles to be extracted > but I imagine it's actually more scalable and healthy to burn jet fuel and reproduce it from renewable powered car…

Cherry-picking the fuel for jets example makes sense, since somehow we don´t expect aviation to transition completely to airscrews.

As for the disposal of HEPA filteres loaded with air-stable inorganics, that still is pollution, only the kind of waste you store safely, and if not give people cancer, but highly localized so.

Re: Iron fuel shows its mettle

#42

Post by PaulHoule » Fri, Jun 23, 2023, 3:43 PM UTC

Re: Iron fuel shows its mettle

#43

Post by upofadown » Fri, Jun 23, 2023, 3:43 PM UTC

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.

Re: Iron fuel shows its mettle

#44

Post by neolefty » Fri, Jun 23, 2023, 3:44 PM UTC

intothemild wrote: post #16

c0nsumer wrote: post #12

Earlier quoted context omitted.

The article says this. It wraps up with: "If these problems can be overcome, you could use renewable electricity to produce iron, store it as long as necessary, transport it there and then burn it for power when needed, says Bergthorson. “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 transmis…

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?

They mention that with hydrogen. It's cheaper to produce hydrogen but much harder to transport it. Fortunately, hydrogen can reduce iron oxide, which turns out to be a great complement. Their analysis is that the system cost of burning iron and renewing it at electrolysis plants is lower cost (and safer) than using hydrogen directly.

Re: Iron fuel shows its mettle

#45

Post by sudhirj » Fri, Jun 23, 2023, 3:44 PM UTC

juujian wrote: post #27

proto-n wrote: post #20

Earlier quoted context omitted.

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.

The article mentions a HEPA filter.

That’s still a mess, if the particles are magnetic a magnet will be a way cleaner and more effective filter.

Re: Iron fuel shows its mettle

#46

Post by balaga01 » Fri, Jun 23, 2023, 3:45 PM UTC

dmix wrote: post #35

TheGeminon wrote: post #26

Earlier quoted context omitted.

I think this is likely more of an energy storage project, rather than an energy production one (which seems to be the stance the article takes). At grid-level, battery tech is challenging, requiring technologies like pumped storage that require particular environments (e.g. damming a river) and can't really be transported. If this works out you could use excess solar during the day to deoxidize the rust produced, and…

How does that battery/production distinction work? How is it a battery if it is consuming/burning a fuel? More as a stable fallback or something?

Well, if you can burn it to produce energy + spent fuel

and then put back energy in the spent fuel to make new fuel again

then you have really a battery. That's how li-ion batteries work. The issue is the efficiency: how much of the energy you used to recharge the "battery" (iron) is going to be available when you discharge (burn) it

Re: Iron fuel shows its mettle

#47

Post by noodlesUK » Fri, Jun 23, 2023, 3:45 PM UTC

kinnth wrote: post #21

c0nsumer wrote: post #12

Earlier quoted context omitted.

The article says this. It wraps up with: "If these problems can be overcome, you could use renewable electricity to produce iron, store it as long as necessary, transport it there and then burn it for power when needed, says Bergthorson. “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 transmis…

This is actually the same principle as BTC. High volume cheap electricity is used to process random numbers and the value is stored as BTC allowing it to be freely transferred once first mined. The green economics of this need some serious consideration as i'd be really aware if you can reprocess it and get a second reaction for less energy than it cost you to turn the rust back into free iron metal.

There's a pretty big difference between BTC and a burnable fuel. It is not possible to turn BTC back into electricity directly, it is only possible to turn it into electricity by first turning it into money, which then buys more electricity (from any, renewable or non renewable) power source. You can't ship someone a container of memory sticks containing BTC and then they get power out of them without burning more fuel or building more solar panels/other renewables. The much better comparison would be hydrogen, which can be produced using readily available water and renewable electricity, shipped, then burned. The difference is that hydrogen doesn't really produce much in the way of by products when burned.

Re: Iron fuel shows its mettle

#48

Post by neolefty » Fri, Jun 23, 2023, 3:46 PM UTC

jacknews wrote: post #18

This makes no sense to me. Iron/steel production is one of the largest individual sources of co2 emissions and uses a lot of energy. And then to just burn it back into iron ore for energy - At best you'll only get back the energy you expended to refine it in the first place. Assuming they are burning scrap, it would surely be better to melt it down and recycle it as steel. As energy storage, it may well have more ene…

True, if we're getting it the traditional way.

Fortunately, iron oxide can be reduced using hydrogen. In the article, they conclude that the system cost of shipping iron and iron oxide back and forth from an electrolysis facility (presumably from renewables) is lower than using hydrogen directly as a fuel.

Re: Iron fuel shows its mettle

#49

Post by a3w » Fri, Jun 23, 2023, 3:47 PM UTC

cr__ wrote: post #36

kinnth wrote: post #21

Earlier quoted context omitted.

This is actually the same principle as BTC. High volume cheap electricity is used to process random numbers and the value is stored as BTC allowing it to be freely transferred once first mined. The green economics of this need some serious consideration as i'd be really aware if you can reprocess it and get a second reaction for less energy than it cost you to turn the rust back into free iron metal.

> the value is stored as BTC What value? Where did any value originate in this process?

The maniacs who claimed that something had a price on a market and cost to create claim that this means value was created. From an ecological perspective, nonsense. Economically, somewhat sound.

Misappropriated rare resources cause destroyed nature for the reason that capitalism said it was sound.

Every joule can only be spent once, but and as long as there is no moral coercion, there is a profit to be made from pillaging it from the supply.

Re: Iron fuel shows its mettle

#50

Post by Tade0 » Fri, Jun 23, 2023, 3:47 PM UTC

> “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 proposition here.

In my corner of the world coal is still frequently used to heat homes during winter. A single house uses around 4-6 tonnes of the stuff each season. This heap of coal takes a significant amount of space.

If my back of the napkin calculations are correct, the energy equivalent in iron dust would be half the volume. Of course there's the issue of weight - about 5x that of coal, but perhaps the cost of moving all that iron could be somewhat mitigated by having a rust reprocessing plant in the neighbourhood.