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Iron as an inexpensive storage medium for hydrogen

ethz.ch

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Re: Iron as an inexpensive storage medium for hydrogen

#101

Post by 7952 »

rini17 wrote: post #73
7952 wrote: post #49

Earlier quoted context omitted.

But there comes a point where battery storage has all been used and prices go even higher. You sell at a x6 profit margin. And are able to sell at x3 profit margin for longer than the battery operators. And that assumes that 100% of the fuel would need to come from storage.

You are betting against batteries? That's becoming risky, Na-ion has the potential to be literally as cheap as dirt. And they are not flammable.

I was not betting on anything. Just explaining why poor efficiency may still be economically viable.

I absolutely agree that we should bet on the battery industry. But there is a difference. With battery technology the cost of storing 1GWh is fully coupled to the cost of the equipment. That is not the case when you can store something. It could run for longer durations with the same cost in equipment. You just store more fuel.

Another factor here is industrial capacity. Battery production has amazing capacity for growth. But that is not a zero-sum game. Other parts of industry could also be scaled up.

Its interesting how similar this thread is to debates I have had with people about solar/wind/battery storage. We take one measure and then focus on that exclusively. Whilst ignoring the wider commercial, industrial and technical factors.

Re: Iron as an inexpensive storage medium for hydrogen

#102

Post by rini17 »

7952 wrote: post #101
rini17 wrote: post #73

Earlier quoted context omitted.

You are betting against batteries? That's becoming risky, Na-ion has the potential to be literally as cheap as dirt. And they are not flammable.

I was not betting on anything. Just explaining why poor efficiency may still be economically viable. I absolutely agree that we should bet on the battery industry. But there is a difference. With battery technology the cost of storing 1GWh is fully coupled to the cost of the equipment. That is not the case when you can store something. It could run for longer durations with the same cost in equipment. You just store…

But "just store more fuel" means adding more containers with larger quantities of flammable material, how can it be done without increasing the cost of equipment? That's the issue here. Maaybe if they directly used the iron ore seam underground, but this isn't the case.

Re: Iron as an inexpensive storage medium for hydrogen

#103

Post by pdonis »

credit_guy wrote: post #56

This is a pretty elegant idea. It takes 826 kJ to split a mole of iron oxide (Fe2O3) and it takes 855 kJ to split 3 moles of water (H2O). So if you take H2 and blow over one mole of Fe2O3 you can strip the O3 for the cost of 826 kJ but then by burning the hydrogen in oxygen you get 855 kJ, for a net exothermic effect of 29 kJ, which is a rounding error. The opposite reaction requires 29 kJ, again negligible, there ar…

> I don't see this making any sense for large scale energy storage. Storage tanks for compressed hydrogen enjoy the square-cube law.

This system doesn't store hydrogen. It stores elemental iron (produced from iron oxide, i.e., iron ore, and hydrogen from solar power splitting water into hydrogen and oxygen), and uses steam to get the hydrogen out (and convert the iron to iron oxide) only when the hydrogen is needed.

Re: Iron as an inexpensive storage medium for hydrogen

#105

Post by DoctorOetker »

jillesvangurp wrote: post #85
DoctorOetker wrote: post #34

Earlier quoted context omitted.

would you mind explicitly listing the 4 conversions? I see: 1) generation 2) storage efficiency (energy while storing divided by energy upon release) what are the other 2 you had in mind?

1) generate hydrogen 2) store hydrogen in iron oxide 3) discharge hydrogen again 4) convert it into something useful (electricity, heat, movement, etc.). All those steps lose energy. And there's stuff that happens in between involving pipes, leaky valves, tanks, compression, etc.

this is not compressed hydrogen storage, anyway your 2,3,4 are the same as my round trip storage efficiency 2

Re: Iron as an inexpensive storage medium for hydrogen

#106

Post by goodpoint »

crote wrote: post #38
goodpoint wrote: post #32

Earlier quoted context omitted.

This not a problem at all when using PV. Plus, the generated heat can be used.

The issue is that it's a self-defeating mechanism. PV doesn't produce zero energy during wintertime, they just produce less . You're going to be building additional PV to charge the Season Battery, but those additional panels will also be providing power during the winter. If your battery's efficiency gets bad enough the added winter power from those extra panels is going to be enough to cover the winter shortage - s…

The mechanism you described is tautological. If you assume people will install infinite PV than the problem is solved.

In reality, the battery is needed when the battery is needed. It might be a long cold winter, or maybe just few evenings after rainy days, but a cheap long lasting battery is still useful.

Re: Iron as an inexpensive storage medium for hydrogen

#107

Post by DrNosferatu »

DrNosferatu wrote: post #26

Efficiency is quite low: 40%-60%. I would say it's only worth it if the marginal cost of producing the hydrogen is close to 0.

Isn’t a more viable economic “battery” to just turn on your LLM training massive data center, or Aluminum smelter (or any other high-consumption, low-urgency industrial process) when there’s excess electric production?
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