Hydrogen Could Replace Coke in Steel Production | Hacker News Reader

Hydrogen Could Replace Coke in Steel Production

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76 pointswoodandsteel48 comments

Wow, I have genuinely never heard of coked coal[1] before in my life, and was extremely confused about why a soft drink was involved in the production of steel... I guess you learn new stuff every day.

[1]: https://en.m.wikipedia.org/wiki/Coke_(fuel)

On the other hand it was impossible to grow up in my country not knowing about it because the double meaning was subject to a very popular song: https://en.wikipedia.org/wiki/Mutter,_der_Mann_mit_dem_Koks_...

Official video: https://www.youtube.com/watch?v=0m7bHdcq87o

Translated lyrics: https://lyricstranslate.com/en/mutter-der-mann-mit-dem-koks-...

Important to know:

* Koks: Coke as in coal but also Cocaine as in drug.

* Kohle: Coal but also Money.

The song reflects on the situation after WW2 where people were freezing in the winter and longed for warmth but had no money to pay. This is contrasted with the party generation of the 90s.

Koks is cocaine, not crack cocaine, Koksen is insufflatiing cocaine

I think you're right. I've changed it.

AFAIK people used to heat their homes with that stuff not so long ago.

Only when mandated by smokeless fuel laws usually, coke is less energy dense than regular (anthrocite/bitumous) coal, but more than charcoal, so using it as a household fuel means you need more storage, and spend more time refueling the fire.

This is one of many creative ways of getting rid of direct fossil fuel use in industry and in the economy overall. We need ways to make steel, cement, and fertilizer with alternative processes that do not contribute to greenhouse gas emissions, and techniques like these are extremely useful. They will make a transition away from fossil fuels possible. But all these processes require heat and electricity. The root energy source used to do all these things needs to decarbonized. That's the really big challenge.

Interesting though how if you suppose abundant, low cost renewable energy available at scale exists, the above problems suddenly become tractable and solved.

Unfortunately not and that is one of the main issues. Even if we had limitless carbon-free energy there would still be significant carbon outputs directly from the production process. The article shows one possible way of reducing this for steel, but cement is currently a different ballgame and is a substantial emissions source from its non-energy inputs.

Well with cheap carbon free electricity, we could cut all the CO2 emissions from iron and steel with hydrogen based reduction and about half that of cement manufacture (about half the carbon use is energy cost for heating as per Wikipedia article). Together about 15% of global emissions could be eliminated which is nothing to sneeze at.

In fact many intractable problems in the world can be solved by more clean electricity - eg. 8000 odd skyscraper farms are enough to feed the world eliminating farm-land requirements but would require enormous amount of energy to run - also would represent single points if failure to attack in war - so will need society to evolve

Well they seem to have found a way to decrease carbon emissions while producing cement as well. https://www.bloomberg.com/news/articles/2019-08-30/builders-...

I think there is a hydraulic magnesium silicate hydrate cement that can be made from seawater-derived magnesium without carbon emissions if electricity is cheap enough. These aren't trivial engineering challenges, but they are probably solvable.

“... the technology to make fossil-free steel is already currently operating with natural gas...”

Natural Gas IS a fossil fuel!

Yes. The technology is in use, just using natural gas instead of hydrogen because of cost.

If/when hydrogen becomes cost-effective via direct market forces or mandated at gunpoint by government, the technology is ready.

Got bad news, you can reduce iron electrolytically and bypass the electricity to hydrogen/hydrogen reduction steps.

Is there a well developed industrial process doing that?

It is not well developed, but there are at least two approaches being investigated at lab or pilot scale.

The first involves electrolysis of molten iron oxide.

https://www.bostonmetal.com/moe-technology/

The other approach involves electrolysis of iron ore powder in alkaline aqueous solution.

https://www.siderwin-spire.eu/sites/template.drupal.pulsarte...

I found the Boston Metal link particularly interesting. If you consider it, combined with a small form factor nuclear reactor, you could build an iron ingot producing plant right on top of the deposits in places that would otherwise be forced to ship ore out for external processing.

They're both interesting, but the aqueous approach has some advantages. Keeping materials working at extreme temperature is difficult: basically anything above 1000C gets very hard. And a low temperature approach has the potential very big advantage of being highly dispatchable, since it would not have to be kept running to keep from freezing up. Dispatchable electrochemistry is like half a battery, just great for dealing with intermittent power sources like renewables.

The second link is interesting. I've only seen the paper on the old Norwegian pilot plant before that slide show. The Norwegians were dealing with Iron Sulfide waste from copper mining as the feed stock. Being able to directly reduce solid iron oxide is probably better.

I have also wondered if you could use the iron rich gangue from bauxite mining as a feed source.

There is a paper by a member of a Norwegian research group that ran a pilot plant in the 1950's using iron sulfide as a starting material. I think their efficiency was ~4kwh/kg. On a straight balance sheet it's not competitive against unexternalized fossil fuel based processes. It has the same problem I mentioned with hydrogen reduction. If you're using fossil fuels to create electricity to reduce iron, you can skip that generate electricity step and use the fossil fuel directly. Which is why there has been very little work in this area.

In a world where you have electricity from wind and solar with regular oversupply. And high taxes on carbon based fuels. then I think electrowinning is viable.

Fun fact, since you mentioned Norway -- in the early 1900s, Norwegian industry also used the Birkeland-Eyde process to produce nitric acid for fertilizer from atmospheric nitrogen.

The process is not energy-competitive with other processes, but since the plants in question had very cheap hydropower energy that couldn't be exported for use elsewhere, this was not a dealbreaker.

I'm thinking that energy-intensive industry in early hydropower-friendly regions could get away with using simple but inefficient processes, since the energy couldn't be used for anything better anyway. Sort of like creating a minimum viable product of an industrial process, before optimizing and getting great efficiency increases.

bostonmetal.com

I don’t know whether this counts as “well-developed”.

That's not bad news!

How do the capital costs compare?

The paper I saw was doing it using an aqueous process at ordinary temperatures. Capital costs of the actual cells would likely be very low. Though feed stock processing might not be.

One of things that struck me is if the capital costs are low enough an aqueous process should be something you can bring online and offline rapidly depending on current market rates. Consider Germany already had a few late nights in winder where rates went negative. You can see where I'm going here.

Yeah but the labor costs for an on-call backshift will eat you.

You can't just replace natural gas with hydrogen. Biggest issue is the piping.

Here in the Netherlands we have a lot of natural gas infrastructure (it used to be mandated that every house gets a gas pipe for central heating and cooking). We would like to reuse it for hydrogen, but the pipes we have right now would leak horribly.

Beyond the issues of containing hydrogen, there is another difference. You can't (easily) liquefy hydrogen, whereas liquefied natural gas (LNG) is a big thing.

Yes, but the amount of electrons per gram of carbon is three times as high with CH4 as with C.

CH4 + Fe2O3 >> CO + 2H2O + 2 Fe

3 C + Fe2O3 >> 3 CO + 2 Fe

In air: 2 CO + O2 >> CO2

CO2 is not produced directly at high temperatures because it decomposes at 900 C to CO and O2.

A bigger problem with natural gas is the methane released to the atmosphere when it is extracted. This is actually the largest source of atmospheric methane IIRC.

I'd have figured the methane would be reformed to H2 first: nominally,

H2O + CH4 -> CO + 3 H2 + H2O -> CO2 + 4H2 3H2 + FexOy -> H2O + Fe

about 1.2-1.4x the methane winds up as CO2 (some extra is burned for heating in the reforming step). In this order H2 could be just as easily, but far more expensively, produced via green methods.

Another green way would be to use aluminum to refine iron, Al + FexOy -> Fe + Al2O3. Exothermic, rapid, 'green', but expensive because it costs electricity to make Al.

Also to your main point in modern blast furnaces I believe CO is either recycled or allowed to react with Fe2O3 at lower temperature to go all the way to CO2, saving money on coke: Fe2O3 + 3CO → 2Fe + 3CO2 or Fe2O3 + 3C -> 4Fe + 3CO2

> believe CO is either recycled or allowed to react with Fe2O3 at lower temperature to go all the way to CO2, saving money on coke:

I think in typical blast furnace the CO in the exhaust is used as fuel to run the plant/heat the air blast.

That's why opposition to gas flaring is ridiculous. It's far better for the environment to burn it and turn leaking methane into CO2 + water vapor than let it escape (even if the burning can't be locally used to power anything).

Seems like nuclear heat and electricity can substitute for hydrocarbons. Abundant heat and power within the atom to compensate for lower efficiency.

Solar heat concentration and power generation could maybe come close in some scenarios.

The main problem is stability.

What about hydrogen embrittlement?

I cannot speak directly the process described, but hydrogen embrittlement is an effect of exposure of finished metals to hydrogen gas where molecular hydrogen penetrates the metal walls (H2 is a very small and light molecule with a sort of ambiguous electropotential property) and disrupts the metalic structure.

Presumably use in production would avoid this, possibly through oxydising the hydrogen at some point. I'd like to read a more technical metalurgical description though, and am well out of my depth here.

Update: The process Bloomberg describe may be related to the concept of "hydrogen attack", in which hot, high-temperature hydrogen decarburises (reduces/removes carbon in) steel by combining with it to form methane, with the resulting gas then trapped in the metal matrix itself.

It's not clear if/how this process might function in steelmaking itself, though part of that involves decarburisation through the injection of oxygen to the blast furnace.

See:

https://www.twi-global.com/technical-knowledge/faqs/what-is-...

Doesn't steel require carbon? Where does the carbon come from in a hydrogen process?

About 0.8%. You could throw in coke after hydrogen smelting, and skip the decarburization step that you'd normally need with coke smelting.

A little, but much less. 2Fe₂O₃ + 3C → 4Fe + 3CO₂ consumes a much larger amount of carbon than the 4% in pig iron or the less than 2% in steel.

This could indeed be a big deal. "Coked" coal, or metalurgical coal, accounts for 15% of current (or at least recent-years, the numbers are shifting rapidly as electric generation offloads) global coal use. It's a use that would otherwise be hard to substitute for although there are options.

Previously, the main alternative has been to re-use recycled steel, in electric arc furnaces (hit up https://invido.us for some pretty amazing videos of things going well and/or poorly) which 1) use potentially clean electricity sources and 2) eliminate all coke use. Altneratives to the blast furnace refinement of new steel from iron ore would be a development unprecedented since the introduction of Bessemer process furnaces in the 1860s.

Vaclav Smil writes on many energy and resource topics, and covers steel from both perspectives in his Energy and Civilization and Making the Modern World books. I'd strongly recommend both.

What I'm finding odd with the article is that Bloomberg appear to be principally citing themselves as sources. I'm reviewing literature and there appears to be scientific research dating at least to the 1970s on this topic (that'a a very quick first read by titles).

I'll add possibly relevant links here. Anyone with actual metalurgical knowledge is far better placed to comment than me.

This appears likely the technology in question:

Valentin Vogl, Max Åhman, Lars J. Nilsson, "Assessment of hydrogen direct reduction for fossil-free steelmaking" (2018)

https://www.sciencedirect.com/science/article/pii/S095965261... (PDF freely available)

Also: "Modelling a new, low CO2 emissions, hydrogen steelmaking process" (2013) https://www.sciencedirect.com/science/article/pii/S095965261...

A techno-economic evaluation of the use of hydrogen in a steel production process, utilizing nuclear process heat Authors: L.M.Germeshuizena, P.W.E.Blomb (2013) https://doi.org/10.1016/j.ijhydene.2013.06.076 https://www.sciencedirect.com/science/article/abs/pii/S00406...

Solutions to Hydrogen Attack in Steels (Timmins) addresses the hydrogen embrittlement question: https://www.worldcat.org/title/solutions-to-hydrogen-attack-...

I'm not sure what you meant to link to with that invido.us link, but when I opened it I got an expired cert, followed by uBlock Origin blocking the whole page, followed by a redirect to a different domain whose above-the-fold content was about Minecraft.

Typo. Should have been: https://invidio.us

(Edit window has closed for HN :(

It's an alternative interface to a popular but increasingly advertising-infested and annoying video-hosting platform.

Great, but industrial hydrogen is produced from natural gas.

We need a good alternative source of industrial hydrogen. I have read of catalytic coatings that split water into hydrogen and oxygen, and were considered uneconomical because of the need to process the hydrogen into "something useful". If hydrogen becomes directly useful, the economic equation should balance out differently.

Even electrolysis is a reasonable cost if electrical energy is abundant.

Where does the carbon source come from to turn the iron into steel?

Steel has miniscule amounts of carbon (0.2% is typical). The carbon comes largely from pig iron from the iron making step (where it comes from the coke used to smelt ore) and an oxygen lance is actually used to burn out excess carbon from molten pig iron to reduce the quantity to a level suitable for mild steel.

The chemistry is explained here:

https://www.sciencedirect.com/science/article/pii/S095965261...

How does this impact the use of scrap metal feedstock and direct reduced iron?

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