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Comment by scottLobster | Hacker News Reader

And just like articles about hydrogen, no mention of the extraction/distribution supply chains needed or the costs/emissions involved. Nope, just focus on our fancy (ZERO EMISSION) generator and ignore how the inputs are actually produced.

It has the energy density of coal, only unlike coal it requires both mines as well as smelters/processing facilities to produce the iron powder. So this can only work if we build out twice the infrastructure that coal currently enjoys, with all the costs and emissions therein.

I'm so tired of breathless scientific reporting of "breakthroughs" that ignores any and all economic context. Or, like this article, treats it as a side issue to be addressed with literally one sentence.

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It is not an energy source. It is a (battery) energy storage solution that can scale. Meant to support renewables use at night/ low sun/low wind periods. And not on hourly scale like normal batteries but on year scale on plant level.

Like in an energy plant. That during the day when there Is surpluses they generate iron powder from ironoxide and cheap electricity. And when there is no surplus they burn the iron powder to irononoxid. And they can both be stored at unlimited scale on a heap.

The problem is that that is the same idea that people are proposing with hydrogen energy storage systems. The difference is that hydrogen works a lot like natural gas. You can pipe it and fire up gas turbines with it. It is also useful as a chemical feedstock in many industrial processes. You can also use it to power vehicles, something that you probably can't with this idea.

So in other words, this is a really crappy version of something that already exists. I guess there are three takeaways to be had:

1) We still need large scale energy storage and it simply cannot just be a pile of batteries. It really needs to be a chemical system and it really has to be able to burn.

2) But that always takes you down one road: Hydrogen or something made from hydrogen. That's the only class of chemicals that really works and doesn't involve carbon. This causes a lot of conflict since it is definitely not many people's favored energy storage idea. And since so much FUD has been flung around for so long because of that, many people have become convinced that this inevitability is actually impossible.

3) So you usually end up with two alternative ideas: Something crazy like burning metals. I've heard of burning boron too BTW. This particular proposal is a continuation of that way of thinking. Probably they are all DOA ideas. And the other is something akin to linking all of the grids across world together with vast numbers of HVDC lines. But this too is crazy, especially once you realize the sheer cost and complexity of it all. Not to mention you are still wasting oodles of energy since you have minimal energy storage.

So eventually we end up in this cycle of one crazy idea being proposed after another, and nothing of importance actually being achieved.

We are already using the most economically viable option. The trouble is that it's not sustainable long term. The solution then will not be the most economical one.

Right, but from an emissions standpoint this is a bad idea too. You not going to create an emission-free iron mine/processing supply chain any time soon. This just moves the emissions up the chain and would take decades to build out. It might be just as bad as coal in terms of emissions at the end of the day, and marginally better at best.

Solar, Wind, more/better batteries and nuclear are our best paths forward if we want to take the immediate action we need to take. If crap like this gets traction we'll just have a greenwashed future where all the coal and natural gas plants will be gone, but global emissions will still be high and power will be many times more expensive. Maybe then people will start to do math.

Back when I was in college the Environmental Science majors were a joke because the chemistry classes they took senior year were the same classes the Chemical Engineers took freshman year. I thought my university just had a crappy environmental science program, but after reading a number of articles like this one I'm thinking it might be a more pervasive issue.

Then the issue is with the chemical engineers, who haven't learned the waste, counterproductiveness and foolishess of dismissing other ideas, viewpoints and people. It's a vicious cycle - it greatly limits their ability to learn what they don't already believe, or deal with challenges to their ideas. The only solution is to give no validity to such dismissals.

I was taught that, in part, by a fed-up engineering professor.

Actually rejecting someone's perspective because they lack expertise in the thing they claim to be an expert in is a pretty smart thing to do. Particularly if you can explain why their perspective is wrong because you are in fact an expert and have superior knowledge.

I would hope Environmental Scientists, who are purportedly concerned with things like ocean acidity, pollution, atmospheric makeup, etc would have the chemical knowledge necessary to understand what they're looking at. Apparently whoever designed their curriculum at my almamater thought it was unnecessary.

> We are already using the most economically viable option.

Arguably we always are doing that, by definition. Investment is spending money on current non-optimal returns in exchange for much greater returns later.

If an investment had guaranteed success; if it had no flaws, then it would already have been made. There is nothing flawless in this world - not you or me, not Facebook or Messi, not oil or iron or renewables or nuclear.

The second most economically viable option is basically going to be hydrogen in some way. Either made from renewables or nuclear power, possible natural sources if they exist in quantity. That is why you hear about it so much.

But this fact causes large scale confusion on all sides. For those invested in the existing system, this is a threat. But for those who think it will be some other kind of green technology, this means admitting they were betting on the wrong horse the whole time.

Not really economically viable unless you narrowly focus on profits. For total direct and external costs (i.e. total societal costs) it's already nonviable.

This is another Aluminium Air battery, same concept different metal. None of them considers splitting water is energy intensive and inefficient. Another hydrogen fool cell category fuel imo.

Who cares if it's energy intensive or inefficient if our other option for using the energy is to run it through a big resistor or to not produce it in the first place? This is a tool for repeatedly storing and releasing excess energy from power plants that can't control their output in response to grid conditions. Let's supposed for the sake of argument that battery banks were prohibitively expensive in some applications, and that hydroelectric storage was too damaging to the local environment. In those cases, your only option is to either dissipate any excess energy or to not produce it in the first place.

What this does, then, is provide you an alternative storage medium that is relatively inert until you want to use it. And it provides you a simple self-sustatining scalable chemical reaction that can be started by supplying some initial heat and then goes on to produce even more heat steadily and continuously until you run out of fuel.

You are completely off.

Why don't you try to do a Fermi estimate before voicing your concerns? Maybe things are not so bad.

Steel is one of the few materials that humans produce in quantities exceeding one gigaton per year (the other ones are coal, oil, natural gas, concrete, and 4 agricultural crops, sugar cane, corn, rice and wheat).

A lot of steel is recycled. It depends how you count, but between 60% and 90% of steel is recycled. Still, a lot of steel is produced out of iron ore each year.

Currently to make a ton of steel out of ore we emit about 2.2 tons of CO2, including upstream emissions[1, page 26]. If we make it from scrap steel, we only emit about 0.4 tons of CO2. It is projected that by 2050, both emissions will go to 0.1 tons CO2-equivalent per ton of steel.

The article mentions an energy density of 11.3 kWh per liter. Iron has a density of about 7.9 kg/l so, we're talking about 1.4 kWh per kilogram. From the article, we learn that the way the energy will be extracted from the iron powder is via burning in a regular thermal power plant. Good power plants now have efficiency of up to 64%, but let's says with the new fuel, they'll just produce 50%. The charging part will probably be more efficient, but let's say the round trip will be only 20% efficient. So what? This could still turn out to be much more economically efficient than hydrogen, or any other alternatives. If you want, we can do some estimates there too, but your concern was about emissions, not about profitability.

Let's focus on emissions. Each time you burn one ton of iron powder, you generate (assuming 50% efficiency) about 0.7 MWh of electricity. In the US, on average, in order to produce that much electricity, you emit about 0.5 tons of CO2-equivalent, according to the EPA. If you charge and burn one ton of iron only 5 times, you come out ahead. But you will charge and burn it hundreds if not thousands of times. It's just iron, it's not a battery that degrades over time. It's iron powder, after each round trip, it's iron powder again.

Each ton of iron powder can potentially reduce emissions by thousands of tons of CO2 equivalent. Each year all of humanity emits about 50 gigatons of CO2 equivalent, gross. The planet absorbs about half of that. A fraction of a gigaton of iron powder could help us get rid of all of our emissions.

This thing here could be a revolution. Until now, I thought that our only economic way to store long time or transport long distance electricity is hydrogen. Iron powder solves so many problems with hydrogen.

Feel free to criticize it, but don't simply be dismissive. Bring information to the table, so everyone here can appreciate it was worth their time reading your comment.

[1] https://rmi.org/wp-content/uploads/2022/09/steel_emissions_r...

[2] https://www.epa.gov/energy/greenhouse-gases-equivalencies-ca...

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