Direct Carbon Fuel Cell (DCFC)

Discussion in 'Chemistry' started by ElectricFetus, May 11, 2008.

  1. ElectricFetus Sanity going, going, gone Valued Senior Member

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    The potential with this fuel cell is great, 80% efficiency, compared to 30-35% for coal Rankine cycle power plants! The high efficiency is even better then hydrogen fuel cells because of the lack of entropy lose of converting a high entropy gas (hydrogen) into a lower entropy larger molecule liquid/gas (water). The fuel can be coal, biomass, garbage, any organic matter.

    The technology also gets around the difficulties or cost of gasifying carbon fuels into syngas and water shifting to hydrogen and can use much simpler pyrolysis to carbonize fuels like biomass and garbage (although a fraction of the fuel will be lost as pyrolysis gas, but this can be made into fuel co-products), the waste heat from the reaction could be used to power pyrolysis (although at 80% efficiency their might not be enough waste heat) alternatively the pyrolysis gas could be burned to power preprocessing of the fuels. Counting energy in the co-product pyrolysis gas total plant efficiency would be ~70% (compared to actual cell efficiency of 80%) and without pyrolysis gas would be 33-65% (depending on the fuel used and how much the fuel converts into pyrolysis gas and solid carbon)

    The technology would use either molten salt fuel cells, solid oxide fuel cells or liquid Tin anode fuel cells. The tin anode fuel cells would not even require preprocessing pyrolysis of the fuels and desulfurization (only drying) but would have lower efficiencies of 50-65%, but would produce high enough gas temperatures to power a brayton, rankine or combine cycle systems with final plant efficiency of ~75% being possible (at the cost of having to add turbines, generators, cooling towers, etc)

    DCFC could double the electricity efficiency of coal, or cut the CO2 emission per watt produced in half. DCFC power plant could also use any kind of fuel more easily than and integrated gasification power plant.

    References:
    http://204.154.137.14/publications/proceedings/03/dcfcw/dcfcw03.html
    http://thefraserdomain.typepad.com/energy/2005/12/direct_carbon_f.html
    ...
    http://www.celltechpower.com/technology.htm
     
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  3. ElectricFetus Sanity going, going, gone Valued Senior Member

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    why doesn't anyone care :bawl:
     
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  5. Read-Only Valued Senior Member

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    I do! I didn't see the original post when you made it.

    Very interesting!
     
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  7. ElectricFetus Sanity going, going, gone Valued Senior Member

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    you were just making fun of me? Doesn't anyone see the potential of this?
     
  8. leopold Valued Senior Member

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    potential for who? the corporations?
    you don't seriously believe this will be made available to individuals do you?

    the same analogy can be applied to solar energy.
    the ONLY reason solar energy was never developed is because it would put a lot of generating plants out of business.
     
  9. ElectricFetus Sanity going, going, gone Valued Senior Member

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    What is with cooperate conspiracy theorist? Yes they have inhibited progress, but it is not all in compassing, they are not omnipresent, in fact they have failed horribly in the last few years.

    No, its was because the cost per watt was uncompetitive with existing energy, and the cooperations never consider costs like population and limitation of resources unless forced too. True there is some reluctant to convert, because of the cost of conversion, but primarily its been cost per watt. As solars cost per watt dives below coal (the present cheaps not consider already installed nuclear) it will be up-taken in the economy at a fabulous pace.
     
  10. leopold Valued Senior Member

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    i never proclaimed a conspiracy. it's a fact that corporations will lose vast amounts of money, even to the point of being forced out of business if this technology is made available to individuals.


    uncompetitive for who? the only cost to the consumer would be the purchase price of the panels.

    i'll gaurentee you that when someone figures out how to charge you for sunlight then solar energy will be widely available.
     
  11. ElectricFetus Sanity going, going, gone Valued Senior Member

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    Companies automatically fail or adapter when the economics make it so, if those technologies become cheaper (which they will or are already) its simply a matter of time before the buggy whip makers re-tool or die. In short companies raise and fall all the time, their power is not all encompassing but limited to the economic market and in some causes the limits of natural resources.


    The panels are expensive to make, much more expensive than the infrastructure price of power plants and some time of usage and paying the fuel bills. The cost per watt is all important, but its the initial cost per watt that I'm talking about: long term savings from free energy are usuals if you can't foot the bill to install it in the first place. Todays solar panel systems take years even decades in some cases to pay for them selves (nanosolar would do so in months but I'm not counting it until it sells on the open market)
     
  12. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    I agree -this looks promissing, but not yet demonstrated as practical.

    I liked:
    Reactions of the Carbon Anode in Molten Carbonate Electrolyte [PDF-754KB]
    John F. Cooper, Lawrence Livermore National Laboratory

    and to some extent his other paper also in your first link of OP.

    Graph on page 6 of first paper seems to show surface power density of 0.1W/cm^2 at curent of about 150 ma /cm^2. That is 0.67 V which is not bad drop off from the open circuit volatge of just over 1V. I am too lazy to check, but bet that beats a solar cell at high noon on clear day. (And it works 24 hours /day)

    At noon on equator clear day there is about 1,000W/M^2 (by memory) so that too is 0.1W/cm^2 of sun light, not electric power and I doubt it will get 10% as the power (as the efficience of conversion limits) at same current density (if that is even achievable.) - What do you think?

    Last of OP links touches on my main concern - posioning of the cell with impurities in the fuel.

    Considering how much carbon US has, and potential for doubling the efficiency of using coal for power, you would think the effort should be greater, at least for "Mouth of Mine" central power plants. Certainly would be cheaper and more flexible to ship power than coal. A "side effect" of better transmission lines, longer distances, etc is a nation grid that wind machines could feed. Also as the CO2 produced is very pure it would seem a natural to combined with an algae/ sunlight system producing oil for mobile fuel.

    Thanks for bring this to my attention.
     
    Last edited by a moderator: Feb 20, 2009
  13. ElectricFetus Sanity going, going, gone Valued Senior Member

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  14. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Yes, that is a slicker presentation with more advanced information, probably made more recently than OP's third link (as I recall being by them also).

    It is important to note that the fall off in output with time, is fixed fuel exhustion, not posioning. They need to try some powder fuel flow thru their tubes with contaminate ash separation and then salvaged fuel recycle with new fuel to get idea of how long it can run when fuel exhaustion is not limiting.

    BTW you may want to re-read my last post 9 as I was still editing and adding comments when you posted your #10.
     
  15. ElectricFetus Sanity going, going, gone Valued Senior Member

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    I think page 14 covers some of that, but yeah 100hrs is not very long.
     
  16. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    again - that is fixed fuel charge (batch process) fuel exhaustion. not important as batch process will not be economically viable. -More in my post 11.
     
  17. ElectricFetus Sanity going, going, gone Valued Senior Member

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    What did you expect for laboratory scale few watt reactor?
     
  18. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Not even as much as they got. I was only pointing out that a commercial design is a long way off and a very different flow process.
     
  19. Nasor Valued Senior Member

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    This was very interesting. Thanks for posting it EF.
     
  20. ElectricFetus Sanity going, going, gone Valued Senior Member

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    I never argued against that. I just feel the concept it self deserved 100x more attention and funding and industry research, etc
     

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