SupFanat
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Is there any experiment to produce carbon-neutral steel?
Provided there's enough renewable supply, iron oxide can be reduced with electrochemically produced hydrogen and even carbon can be extracted from
greenhouse gas carbon dioxide using the same hydrogen.
I like paradox decisions such as producing renewable energy in places with only little sunshine. So some windy place is needed.
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Sulaiman
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What is wrong with air and charcoal ?
whatever CO2 produced will be consumed in the next generation crop for charcoal = carbon neutral
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j_sum1
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Yup.
Grow a tree. Make steel. It just takes a bit longer.
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SupFanat
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Aren't there some places on Earth which aren't suitable for growing trees but suitable for producing hydrogen?
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Texium
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Quote: Originally posted by SupFanat  | | Aren't there some places on Earth which aren't suitable for growing trees but suitable for producing hydrogen? |
Let me guess what you're thinking– Antarctica?
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j_sum1
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I don't know of any standard steel-making processes that use hydrogen.
If you ever get a chance -- visit a steel refinery. It is just not the sort of place that you could run off a windmill and a couple of solar panels.
There is coal and lots of it.
The concept of "carbon-neutral" is a bit ill-defined in many practical situations but basically means that over the entire process the total amount of
carbon dioxide released into the atmosphere is offset by the amount of carbon dioxide absorbed from the atmosphere. Not many industrial processes use
CO2 from the air. One method for achieving carbon neutrality is to substitute the energy source for something that does not release CO2, but this is
only really viable if you are using electricity as your energy source. And then it is a bit of an accounting exercise rather than anything real since
for most practical situations the electricity comes from the national grid over which you have no real control. By rights you should also factor in
the CO2 emitted during the manufacture of your wind turbine or solar panels or whatever.
For industrial processes where electricity is not the primary energy source (such as steel-making), the simplest solution is to continue with the
standard manufacturing practice but to also invest in a program for sequestering carbon -- such as the planting of trees. If you buy something that
claims to be carbon neutral, this is likely what has been done.
So, make steel. Plant a tree. (And trees do not grow that well in Antarctica.) There are plenty of places on the earth that could do with some
desert reclamation and reforestation however.
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macckone
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Hydrogen causes steel to become brittle. Not what you want in steel making. You can however use aluminum to produce carbon neutral steel. Provided
the electricity is carbon neutral. The termite reaction was one method of producing zero carbon steel over a century ago.
*edit* If you are refining on the moon for example aluminothermic reactions are the way to go. Infinite sunlight but very little carbon to be had.
[Edited on 31-5-2015 by macckone]
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Polverone
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So called "direct-reduced iron" is made from iron ore and methane, and the process is already in use on an industrial scale. If you wanted to make it
carbon neutral you would capture the waste CO2 for hydrogenation back to methane with electrolytic hydrogen.
Hydrogen appears to be usable by itself; I don't think there would be much residual hydrogen after the crude product is melted for alloying. The main
difference is that pure hydrogen reduction is endothermic:
<a href="http://arxiv.org/pdf/0803.2831.pdf">A LABORATORY STUDY OF THE REDUCTION OF IRON OXIDES BY HYDROGEN</a>
<a href="http://babel.hathitrust.org/cgi/pt?id=mdp.39015078527085;view=1up;seq=7">Melting pyrophoric hydrogen-reduced iron powder for production
of steel</a>
The carbon that is actually incorporated in the steel can come from charcoal as others have suggested.
PGP Key and corresponding e-mail address
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blogfast25
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Thanks for these papers.
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macckone
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| Quote: Originally posted by Polverone | So called "direct-reduced iron" is made from iron ore and methane, and the process is already in use on an industrial scale. If you wanted to make it
carbon neutral you would capture the waste CO2 for hydrogenation back to methane with electrolytic hydrogen.
Hydrogen appears to be usable by itself; I don't think there would be much residual hydrogen after the crude product is melted for alloying. The main
difference is that pure hydrogen reduction is endothermic:
<a href="http://arxiv.org/pdf/0803.2831.pdf">A LABORATORY STUDY OF THE REDUCTION OF IRON OXIDES BY HYDROGEN</a>
<a href="http://babel.hathitrust.org/cgi/pt?id=mdp.39015078527085;view=1up;seq=7">Melting pyrophoric hydrogen-reduced iron powder for production
of steel</a>
The carbon that is actually incorporated in the steel can come from charcoal as others have suggested. |
From the second article, you also have to deal with an iron and hydrogen substance that is highly combustible. In other words feasible but may not be
practical. It also doesn't give end product properties which are the primary concern with hydrogen embrittlement. However it does give ideas for a
superb reducing compound.
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blogfast25
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| Quote: Originally posted by macckone | | It also doesn't give end product properties which are the primary concern with hydrogen embrittlement. However it does give ideas for a superb
reducing compound. |
You're referring to super fine, pyrophoric iron, I assume?
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macckone
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Assumptions are occasionally correct.
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