Joined: Aug 03, 2007 Posts: 3644 Location: Boston Suburbs
Posted: Thu Mar 06, 2008 1:17 pm Post subject: Re: Is it possible to build a wind turbine without fossil fu
EnergyUnlimited wrote:
Carbon is required to reduce iron oxides (iron ores) to metallic iron.
Could you clarify? "Carbon" by itself isn't a fossil fuel. It's just a feedstock. The important thing is to try to generate the required heat electrically and minimize CO2 emissions.
It takes a lot of electricity, but it is already being done today. So it seems that windmills would have enough positive EROEI to feed back into the maintenance and creation of more windmills.
This is news to my ears! My doomer score just fell about 10%.
We can make steel without burning coal? Sweet!
My future scenarios often involved the mass burning/replanting of forests in order to create charcoal to melt steel to build energy infrastructure (whatever form it would take)
Cut out the horrific forest monocrop/charcoal stage and the system is far more sustainable.
Sure, you can capture the emissions and do CO2 electrolysis to recapture the carbon.
You can also do molten oxide electrolysis similar to aluminum refining, but this technology is in its infancy, and unlikely to be competitive while we still have coal.
Posted: Thu Mar 06, 2008 1:51 pm Post subject: Re: Is it possible to build a wind turbine without fossil fu
mos6507 wrote:
EnergyUnlimited wrote:
Carbon is required to reduce iron oxides (iron ores) to metallic iron.
Could you clarify? "Carbon" by itself isn't a fossil fuel. It's just a feedstock. The important thing is to try to generate the required heat electrically and minimize CO2 emissions.
OK, we are now using "coke", which is pyrolyzed, high quality coal, for example anthracite.
Such coke contains 97% of carbon or so.
Coke is mixed with magnetite ore (iron oxide Fe3O4) and loaded to smelter.
Air enriched with oxygen is admitted in, coke is partially burning to produce carbon monoxide gas (CO) and adequate temperature.
4C + 2O2 ---> 4CO + heat
Carbon monoxide is an actual reducing agent and it reduces iron oxide to iron:
Fe3O4 + 4CO ---> 3Fe + 4CO2
At process temperature (~1400*C) CO2 is combining with excess of coke (C) forming CO:
4CO2 + 4C ---> 4CO
So it is possible to describe overall process as:
Fe3O4 + 4C ---> 3Fe + 4CO
So we can see that in theory 4 Moles of coke (48 gram) is needed to produce 3 Moles of iron (168 gram).
You cannot substitute this carbon with electricity.
I have tried to make chemistry as simple as possible to demonstrate this process.
Posted: Thu Mar 06, 2008 2:31 pm Post subject: Re: Is it possible to build a wind turbine without fossil fu
Dezakin wrote:
Sure, you can capture the emissions and do CO2 electrolysis to recapture the carbon.
That is crap.
You cannot do CO2 electrolysis because it is not an ionic substance.
It does not conduce electricity and does not undergo electrolysis.
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You can also do molten oxide electrolysis similar to aluminum refining, but this technology is in its infancy, and unlikely to be competitive while we still have coal.
... and even if you do use electrolysis, you will still need highest grade processed carbon (graphite) for anodes.
These anodes are sacrificial at the process temperature and you will not use less carbon then theoretical amount needed for chemical reduction.
The same holds true for aluminum produced by electrolysis of solution of Al2O3 in criolite (Na3AlF6) at ~1000*C :
Cathode:
2Al(3+) + 6e(-) ---> 2Al (metal)
Anode:
3O(2-) - 6e(-) ---> 3[O]
Oxygen immediately react with graphite anode:
3[O] + 3C ---> 3 CO
So overall process can be described as:
Al2O3 + 3C (electrolysis)---> 2Al + 3CO
So in fact production of aluminum is even more carbon intensive then production of iron.
For every 2 Moles of Aluminum (54grams) you need 3 Moles (36grams) of carbon in pure form (graphite).
Unfortunately you cannot use other electrode, which does not react with oxygen (platinum or few other metals from this group could be considered).
That is because you would lose excessive amounts of precious metal.
1. Fluorine by-product produced from electrolysis of criolite flux will react with platinum (or any other imaginable conductor) at 1000*C (process temperature) forming platinum hexafluoride gas or fluoride of other metal.
2. Platinum (or other metals from this group) are forming alloys with molten aluminum metal and that reaction is proceeding with explosive violence if care is not taken - you will lose further amounts of precious metal dissolved in your aluminum.
So, sorry man, cannot be done.
No carbon = no aluminum (or iron) from oxide electrolysis.
Weather its cheaper to just electrolysize the CO2 emitted from the process to recapture the carbon is a different question.
That is also crap.
See my post above.
NB. Peoples from your reference are also having electrode problem.
Conductive FeO will oxidize itself to non conductive Fe2O3 under process conditions and your problem will take a form of necessity of frequent electrode replacement - not suitable beyond laboratory scale.
On the top of that you would need Fe3O4 purified by wet chemistry process.
Expensive to the extreme.
Acid treatment of millions of ton of iron ores would be needed, followed by reprecipitation of iron oxide etc.
Lets not be so damned contrary. This isn't religeon. CO2 can be reduced.
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You can also do molten oxide electrolysis similar to aluminum refining, but this technology is in its infancy, and unlikely to be competitive while we still have coal.
... and even if you do use electrolysis, you will still need highest grade processed carbon (graphite) for anodes.
These anodes are sacrificial at the process temperature and you will not use less carbon then theoretical amount needed for chemical reduction.
While this is true of aluminum refining today it might be possible to find alternatives in the future for steel refining; Your objections are to particular solvents and their byproducts (fluorines)
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The same holds true for aluminum produced by electrolysis of solution of Al2O3 in criolite (Na3AlF6) at ~1000*C
Unfortunately you cannot use other electrode, which does not react with oxygen (platinum or few other metals from this group could be considered).
That is because you would lose excessive amounts of precious metal.
1. Fluorine by-product produced from electrolysis of criolite flux will react with platinum (or any other imaginable conductor) at 1000*C (process temperature) forming platinum hexafluoride gas or fluoride of other metal.
I cant speak on the development of new processes, and I feel we're being unnecissarily pessimistic, especially with potential advances in material science. For instance, Hastelloy doesn't react with fluorine in FLiBe salt when berrylium is added to reduce the electrochemical potential. We cant say that similar techniques couldn't be applied to potential problems with aluminum or steel production. It may be that steel production via molten oxide electrolysis is possible with durable anodes where its impossible in aluminum refining... its too early to tell.
And in any case, we can allways recapture the CO2 from the traditional tried and true process of steel refining and reduce it to CO.
Posted: Thu Mar 06, 2008 3:52 pm Post subject: Re: Is it possible to build a wind turbine without fossil fu
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As long as you don't use steel for construction.
You could connect Dutch-type XVII-th century windmill design with electricity generator.
Some copper needed for generator you could smelt with renewable charcoal.
However if you want to run modern cities with that design - forget it.
The Dutch type windmills have a maximum power coefficient of around 0.2 over their operating range, their tip speed ratio during operating varying from about 1.5 to 4, and Cp even drops to 0.05 at some points. A very poor choice.
It is possible to built a 25-foot diameter 3-blade rotor using wood and you will get more than double the efficiency. In fact, steel is often recommended against for this due to increased danger if the rotor breaks in severe weather conditions. _________________ The unnecessary felling of a tree, perhaps the old growth of centuries, seems to me a crime little short of murder. ~Thomas Jefferson
Posted: Thu Mar 06, 2008 4:03 pm Post subject: Re: Is it possible to build a wind turbine without fossil fu
Dezakin wrote:
I cant speak on the development of new processes, and I feel we're being unnecissarily pessimistic, especially with potential advances in material science. For instance, Hastelloy doesn't react with fluorine in FLiBe salt when berrylium is added to reduce the electrochemical potential. We cant say that similar techniques couldn't be applied to potential problems with aluminum or steel production. It may be that steel production via molten oxide electrolysis is possible with durable anodes where its impossible in aluminum refining... its too early to tell.
And in any case, we can allways recapture the CO2 from the traditional tried and true process of steel refining and reduce it to CO.
I am not trying to be pessimistic for a sake of doing so.
I am providing a very good reasoning for my pessimism here.
It is not an attempt to find problems, even if these are not there.
To be fair for these carbon free electrolytic approaches, I see them quite hopeless from economic perspective, but aluminum case is more hopeless then iron one.
You seem to have some chemical education (and I also do), so you can definitely work out why it is so.
I do not claim that it is impossible to make an iron or aluminum without resorting to carbon use.
I could offer many ways to achieve it right now.
However these would increase price of product by 1-2 orders of magnitude, suffer from scaling up problems etc.
That is not an easy engineering.
[I had to split this post here for a reason of an "unacceptable" error - EU]
Last edited by EnergyUnlimited on Thu Mar 06, 2008 4:22 pm; edited 1 time in total
Posted: Thu Mar 06, 2008 4:15 pm Post subject: Re: Is it possible to build a wind turbine without fossil fu
[continuation]
Look, you are talking about 1000 - 1500 *C temperatures and coping with nascent oxygen sometimes contaminated with fluorine there.
This is immense problem.
I can foresee a process of carbon free iron or aluminum making, but their price would have to be comparable with current titanium or zirconium prices.
Needless to say we would not apply such expensive products for example for production of reinforced concrete.
Re. Carbon dioxide - monoxide reprocessing.
Yes, we can do it, but I think it would be far cheaper to rely on natural carbon cycle.
After all sugar from sugarcane produced in annual quantities of many millions of tons can be calcinated to produce pure carbon, or even graphite if you increase temperature further and apply moderate pressure.
Last edited by EnergyUnlimited on Thu Mar 06, 2008 4:21 pm; edited 1 time in total
Posted: Thu Mar 06, 2008 4:17 pm Post subject: Re: Is it possible to build a wind turbine without fossil fu
[quote="EnergyUnlimited"]
Dezakin wrote:
I do not claim that it is impossible to make an iron or aluminum without resorting to carbon use.
I could offer many ways to achieve it right now.
However these would increase price of product by 1-2 orders of magnitude, suffer from scaling up problems etc.
That is not an easy engineering.
Well no. It makes the whole game interesting.
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Re. Carbon dioxide - monoxide reprocessing.
Yes, we can do it, but I think it would be far cheaper to rely on natural carbon cycle.
After all sugar from sugarcane produced in annual quantities of many millions of tons can be calcinated to produce pure carbon, or even graphite if you increase temperature further and apply moderate pressure.
Sure, but we wont have to do that for centuries, when the coal really starts to run out beyond it being merely too expensive to burn for electricity. By then steel demand may be so large (as well as synthetic fossil fuels) that sugarcane just isn't nearly enough. We're allready at 780 million tons of steel per year...
And using onsite processing may be cheaper after all.
Posted: Thu Mar 06, 2008 4:32 pm Post subject: Re: Is it possible to build a wind turbine without fossil fu
Dezakin wrote:
Well no. It makes the whole game interesting.
Then you are relying on technology [cheap carbon free manufacturing of iron] which is not there.
Could you propose details of any prospective scheme, so I can comment upon?
Any details of the process proposed in your reference?
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By then steel demand may be so large (as well as synthetic fossil fuels) that sugarcane just isn't nearly enough. We're allready at 780 million tons of steel per year...
I think, at that point we will face demand destruction.
Heck, we are beginning to see it right now with collapse of American housing market.
Demand for new houses is being destroyed.
Posted: Thu Mar 06, 2008 5:04 pm Post subject: Re: Is it possible to build a wind turbine without fossil fu
EnergyUnlimited wrote:
Dezakin wrote:
Well no. It makes the whole game interesting.
Then you are relying on technology [cheap carbon free manufacturing of iron] which is not there.
Could you propose details of any prospective scheme, so I can comment upon?
Any details of the process proposed in your reference?
No, I'm honestly unsure what techniques people will be using in a hundred years. I just mean its an interesting problem that isn't necissarily unsolvable. Say they find some solvent and anode that dont fight each other, or you use some other recyclable reducing agent besides carbon thats easier to reprocess.
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By then steel demand may be so large (as well as synthetic fossil fuels) that sugarcane just isn't nearly enough. We're allready at 780 million tons of steel per year...
I think, at that point we will face demand destruction.
Heck, we are beginning to see it right now with collapse of American housing market.
Demand for new houses is being destroyed.
We're veering off topic into the civilization will expand or implode debate. I think automation of production of capital will continue to drive up demand even if its more consumptive of resources.
Posted: Thu Mar 06, 2008 5:28 pm Post subject: Re: Is it possible to build a wind turbine without fossil fu
Dezakin wrote:
No, I'm honestly unsure what techniques people will be using in a hundred years. I just mean its an interesting problem that isn't necissarily unsolvable. Say they find some solvent and anode that dont fight each other, or you use some other recyclable reducing agent besides carbon thats easier to reprocess.
I can suggest direct reduction of iron oxide ore (magnetite) with hydrogen produced for example in nuclear plant and smelting resulting iron powder in electric furnace.
Certainly doable and in fact easy process, but price will go up quite a lot.
It would be still much cheaper, then your molten oxide electrolysis though.
On the other hand there is no easy way with aluminum.
Conversion of bauxite to aluminum oxychloride AlOCl by easy chemistry and following reduction of it with sodium or potassium according to reaction:
3AlOCl + 3Na ---> Al + Al2O3 + 3NaCl
would be a best idea.
AlOCl would be prepared by some modification of current method of initial bauxite processing and would not be expensive.
Sodium from electrolysis of salt.
However price of so produced Al would be comparable with current prices of titanium.
Posted: Thu Mar 06, 2008 6:25 pm Post subject: Re: Is it possible to build a wind turbine without fossil fu
EnergyUnlimited wrote:
Dezakin wrote:
No, I'm honestly unsure what techniques people will be using in a hundred years. I just mean its an interesting problem that isn't necissarily unsolvable. Say they find some solvent and anode that dont fight each other, or you use some other recyclable reducing agent besides carbon thats easier to reprocess.
I can suggest direct reduction of iron oxide ore (magnetite) with hydrogen produced for example in nuclear plant and smelting resulting iron powder in electric furnace.
Certainly doable and in fact easy process, but price will go up quite a lot.
It would be still much cheaper, then your molten oxide electrolysis though.
Bah, its not my process, its just one of the techniques being toyed with. I thought that hydrogen refining of steel impregnates it with hydrogen that causes very poor metallurgical performance. Is this significantly less expensive than direct CO2 reprocessing?
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On the other hand there is no easy way with aluminum.
Conversion of bauxite to aluminum oxychloride AlOCl by easy chemistry and following reduction of it with sodium or potassium according to reaction:
3AlOCl + 3Na ---> Al + Al2O3 + 3NaCl
would be a best idea.
AlOCl would be prepared by some modification of current method of initial bauxite processing and would not be expensive.
Sodium from electrolysis of salt.
However price of so produced Al would be comparable with current prices of titanium.
Sounds good.
Sometimes I wonder what the far future will bring. For instance plasma confinement seems to be a dead end for fusion, but it might prove useful someday in advanced materials processing. I cant see how today, but say you can keep corrosive plasma from eroding away your walls, then you could just thermally decompose bauxite. Any other far out ideas?
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