I'd much rather be dealing with industrial quantities of CO2 than Cl2, if that stuff gets into the atmosphere in bulk I doubt it'd end well. The article seems to suggest that the chlorine can be solved commercially so the argument seems to be that it is economical to sequester the chlorine rather than the carbon dioxide.

There are some obvious risks of being left with large amounts of Chlorine to try and find a home for, but the idea is at least plausible on face value.

Big use-case, problem is that in case of fire lots of dioxins are produced.

The costs of CO2 - the real costs, not the subsidized ones - are extraordinarily high, possibly leading to the worst global catastrophe in human history. What is the cost of Cl2?

With the passing of time the answer might not be so clear.

The frogs in the 2 degree warmer pond will be complaining a lot more than the other frogs, so that must be worse.

The pre-industrial levels of CO2 were around 280ppm, while the current CO2 levels are around 440ppm.

For Cl2, in occupational-health situations the permissible exposure is around 1ppm per hour, or 3ppm for 15 minutes. So the 160ppm we'd throw into the atmosphere in this thought experiment (or even the 52ppm at the suggested discount) is going to cause some pretty big problems pretty rapidly.

The problem with H2O wouldn't be the absolute amount, but the changes brought on by the added H2O. For one thing, it would rain pretty much 24/7 in Florida. :) (Yes, I know it's not at all that predictable.)

with carbon and hydrogen from natural gas/coal gasification: CH4 + CO2 -> 2CO + 2H2 Fe2O3 + 3CO -> 2Fe + 3CO2 (exothermic in >50% H2 environment)

with water-sourced hydrogen: 2H2O -> O2 + 2H2 Fe2O3 + 3H2 -> 2Fe + 3H2O (endothermic, requires energy input)

There are two issues with using hydrogen, which can be overcome:

>"The energy balance of the shaft furnace is affected by the absence of the exothermic carbon monoxide reduction. . . Thus, it is necessary to add energy to the shaft furnace to carry heat in the burden."

>"The second issue is the resulting DRI carbon content; the DRI will have 0% carbon with pure hydrogen. The majority of DRI is used in EAFs, and EAF steelmaking practice generally employs carbon addition... Under current melting practices, it will be necessary to add hydrocarbons at some place in the process to achieve the desired carbon level... However, this added carbon will then be converted to CO2 in the EAF... Alternatively, carbon from a renewable source (like biomass) could be used."

https://www.midrex.com/tech-article/ultra-low-co2-ironmaking...

https://www.cetjournal.it/cet/23/100/112.pdf

¹https://www.nature.com/articles/s43247-023-00857-8

Comparing the effect of one kg of H2 with one kg of CO2 is irrelevant if we don't know how much H2 is released compared to the amount of CO2 for corresponding processes to produce the same amount of goods.

It's remarkably hard to find organic compounds that are less-bad than CO2 though. It really is the very bottom of a local minimum.

CO2 by itself is not particularly bad. We are just emitting a LOT of it.

https://project-helios.space/green-steel/

IIRC there was already a thread some time ago about electrolysis of iron ore in sodium hydroxide (as reusable solvent) where I was wondering about the cost of NaOH and how much would have to be replenished per cycle. But that process easily whoops this one.

1: Cl2 + MgO >> MgCl2 + O2, for one. (Stoichiometry exercise for the reader.)

> Even so, scaling production to match industrial chlorine gas needs would still produce tens of millions of tons of CO2-free iron and chlorine annually

> The Oregon group's setup generates essentially as much chlorine gas as it does iron, notes Iryna Zenyuk, a chemical engineer at the University of California, Irvine.

But likely replacing 100% of steel industry with this process would still produce more chlorine than can be profitably sold currently. Maybe it would do with replacing 30%, for starters.

The only issue is cost.

So if there is a lower energy way of producing green steel it is at least worth exploring.

Meaningful solar, hydro, nuke and wind power plants are quite concentrated (100MW-few GW) anyway.

If anything, solar/wind are less suitable due to intermittent output and would require hydrogen buffer storage.

https://reneweconomy.com.au/fortescue-says-regenerative-infi...

They're also hiring Software Architects and embedded engineers (along with Engineers)

https://careers.fortescue.com/job/Perth-Senior-Software-Arch...

https://careers.fortescue.com/job/Perth-Embedded-Test-Engine...

Perth, Western Australia based.

His grand grand folks landed here as domestic servents to settlers, and their kids made out okay: https://en.wikipedia.org/wiki/John_Forrest

Twiggy's a rare breed of pastoral based hard rock mining billionaire and marine biologist who gives a toss about the environment .. which helps given the intersection of family lands and native title claims.

To the extent they have stopped taking tax credits for diesel fuel as they start trialing electric/hydrogen/ammonia fueled equipment. (while also researching into green steal production and hydrogen electrolyzer production.)

The manufacturer initially sold them as reducing CO2 globally, and also reducing harmful emissions in the mine itself, and saving fuel and fuel transport costs to remote mines.

The miners reported that the key benefit was actually that the machine spit out a lot less heat in a confined space undeground. Previously they'd need to spend an hour using AC to reduce the temperature to a level that humans could cope with before sending workers in for the next stage. With the EVs that time was saved and work could begin immediately.

https://www.wri.org/technical-perspectives/insider-not-all-e...

Solar is worse, but since most modern high quality tables include LCOE's for "solar" and "solar+battery" with very different numbers, it shouldn't be misleading.

Just using electricity is probably cheaper and easier; large power plants are crazy efficient already.

I can only what hot molten salt does to industrial processes.

https://en.m.wikipedia.org/wiki/Nuclear_lightbulb

Like it was not crazy dangerous enough. ;-)

An array of SMRs (small modular reactors) located at the steel factory could be used – and would be sufficient – both for heating and producing the electricity without interruptions caused by fluctuating prices or blackouts.

0 https://en.m.wikipedia.org/wiki/Kitimat

Cheap in terms of money, maybe.

Less so in terms of emissions: https://www.statista.com/statistics/1291468/international-sh...

They are running something similar with goal of larger industrial scale.

I think the devil is really in pre-processing ore. Whatever process can do that most cheaply is likely to win out. If you can figure out how to use waste like red mud so much that better.

https://www.theguardian.com/business/2024/jan/18/tata-steel-...

It is worth considering the environmental footprint of our trading partners, but note that they are rapidly improving as well as renewables come down the cost curve.

https://energyandcleanair.org/publication/chinas-new-coal-po...

The UK industry is just uneconomic, it's not a green issue.

https://upload.wikimedia.org/wikipedia/commons/1/15/World_fo...

https://bostonmetal.com/green-steel-solution/

EDIT: For clarity, based on comment below.

In fact, the real score for reducing pollution here is efficiency mods - electric smelters plus steam engines apparently produce the exact same amount of pollution as just using lv2 smelters directly so you'll need those efficiency mods anyway (unless you've already switched to solar+nuclear), but you're better off putting your initial efficiency mods into your miners and oil.

Solar and nuclear are both a pain in the ass to switch to, though - nuclear takes stacks and stacks of copper to build and is a PITA to set up centrifuges and pipe down hydrochloric acid to uranium, and solar needs bots to place with any speed. It's just easy to slap down steam engines fed by either coal or solid fuel. So if you prioritize player-time over strict efficiency then the quickest way of reducing pollution is almost certainly efficiency mods into pre-existing buildings (i.e. miners and oil), and building electric furnaces will in-practice force you to build more power plants anyway. At least, in my experience. But maybe that's due to the prod-mods and beacons.

Sticking points for me were, massive chlorine gas production (extremely toxic...) and requiring extremely high purity iron ore, with costs to purify it hand waved away.