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Iron fuel shows its mettle

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Re: Iron fuel shows its mettle

#51

Post by 13of40 »

thsksbd wrote: post #30
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.

iron oxide magnetic properties depend on its oxidation state, temperature and particle size.

Not sure why this is dead, but AFAIK magnetism in iron and steel is dependent on "domains" of iron molecules that are aligned in a crystal structure so the magnetic effect isn't just scattered to all directions. That's why some kinds of stainless steel aren't magnetic - the adulturant elements break up the crystal structure. In this case I think the question would be whether these particles are big enough to form a "domain" and become magnetic.

Re: Iron fuel shows its mettle

#52

Post by PaulHoule »

juujian wrote: post #25
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…

Might be possible to create a completely closed system to address the loss? I am more concerned/confused by the fact that they use hydrogen to reduce the iron. That seems like a very convoluted process, why not use the hydrogen generate heat instead? Yes, it has much lower density, but it has advantages to make up for it, for instance the fact that you don't need to worry about evaporation, leakage, filters, all that…

Hydrogen is devilishly hard to transport and store. Hydrogen packs a lot of energy per gram, but the density is so low. You need a huge tank if you compress it as a gas, you can liquefy it but the density is still not great, it takes a lot of energy, and you have to deal with this:

https://en.wikipedia.org/wiki/Spin_isomers_of_hydrogen

freshly liquefied hydrogen contains a lot of stored energy in that form which will be released over time and cause quite a bit to vaporize, for long term storage you have to release that energy.

Thus people have looked at all sorts of schemes for storing hydrogen such as absorbing it in metals like palladium, metal hydrides, chemical carriers such as ammonia, methane, etc.

Re: Iron fuel shows its mettle

#54

Post by skyechurch »

OrbitalPewPew wrote: post #19

Imagine thinking that a material stars can't use for fuel is one that makes sense as a "renewable energy source." These idiots need to go back and take undergraduate thermodynamics.

You can't extract energy from iron by nuclear fusion, which is how stars "burn" fuel, but this is a chemical process, Fe + O2 => (some Fe&O compound) + energy.

Re: Iron fuel shows its mettle

#55

Post by jshorty »

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.

Not sure I agree, on one hand you have actual, physical potential energy, on the other hand you have numbers on a computer that could become worthless depending on unpredictable economic factors.

Re: Iron fuel shows its mettle

#56

Post by neolefty »

bioemerl wrote: post #15
FrustratedMonky wrote: post #2

Doesn't this seem like we are just going to use up iron supplies. Iron would then become a used up commodity and drive up prices. Just like when Corn was used for ethanol, the side effect was driving up corn prices, and raising food prices. This could use up Iron, and then impact a ton of stuff. EDIT Missed this: "This can later be reduced—that is, the oxygen can be stripped away—back into iron powder. “You can think…

Iron is one of the most abundant elements on earth, but also we aren't going to be burning it like we do fuels now. Instead we would produce pure iron using green power and oxidize it back to it's natural state for energy in a cycle. Imagine loading an iron rod into your car, driving for a while, and then when you get into the gas station you dump a pile of rust off and buy a fresh iron bar.

Some societal implications:

* Kids playing with iron filings sounds a lot safer than kids playing with gasoline. "Don't leave your magnets in the fuel tank; it clogs up the lines!"

* The gasoline party scene in Zoolander would need to be reconsidered.

Re: Iron fuel shows its mettle

#57

Post by wongarsu »

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?

Non-rechargeable batteries are also consuming a fuel. The products just stay in the same enclosed container. Same with rechargable batteries, just that there the process is easily reversible.

It is a bit of a fuzzy distinction. Batteries are typically simple chemical reactions that cause electrons to move around. But viewed from the outside a hydrogen fuel cell behaves the same; so why not call this one a battery too (especially since the process is reversible).

Re: Iron fuel shows its mettle

#58

Post by kumarvvr »

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…

If a power plant has sufficient store of Iron, with a complete cycle, from burning iron to recovering iron, then it is no longer a consumable.

I can imagine a solar plant, making iron in the day and burning it in the night and essentially act as a base load plant, the holy grail of renewable energy.

Re: Iron fuel shows its mettle

#59

Post by rcme »

Is iron oxide really that much more volumous than iron? In terms of capturing the iron oxide, why couldn’t this be run in a sealed container with a valve that allows oxygen in? This doesn’t work for hydrocarbons because the volume of CO2 is orders of magnitude greater than the volume of fuel, but does iron oxide have the same issue?

Re: Iron fuel shows its mettle

#60

Post by rfreytag »

I assume they are using renewable energy to reduce naturally-occurring iron oxide.

When the iron is burnt are they going to do with pure oxygen? Otherwise they'll get pollutants like nitrogen dioxide, possibly ozone. And the 0.5% not burnt will also become a pollutant unless carefully removed in some smokestack scrubber.

Or is this 'burning' to occur some kind of iron fuel cell? How would they liquidize the iron which is quite heavy?

Lastly, iron is heavy. Moving reduced iron could be expensive and dangerous.

Still, if sufficiently close to the renewable source this could provide much needed load leveling for intermittent sources.

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