[ExI] Coal Gasification and CO2 (was Re: Whatever happened to peak oil by 2020?)

[Kelly Anderson]

On Sat, May 11, 2013 at 6:26 PM, spike <spike at rainier66.com> wrote:

>
>
> *From:* extropy-chat-bounces at lists.extropy.org [mailto:
> extropy-chat-bounces at lists.extropy.org] *On Behalf Of *Kelly Anderson
> *Sent:* Saturday, May 11, 2013 4:56 PM
> *To:* ExI chat list
> *Subject:* Re: [ExI] Coal Gasification and CO2 (was Re: Whatever happened
> to peak oil by 2020?)****
>
> ** **
>
> Ja, what I meant was use wind and ground based solar as an energy input to
> convert coal to Diesel and octane.  The plant you cite burns coal to make
> the power to convert coal to liquids.  This is a huge waste of coal.  When
> you have solar and wind power available, use that power to drive the coal
> conversion.****
>
> ** **
>
> >…I'm not a great chemist, and the chemical composition of coal is very
> complex, but my understanding of it is that to convert the carbon chains in
> the coal to octane, you have to release carbon dioxide. This isn't from the
> burning of the coal itself, but as a side effect of the conversion. I could
> be wrong, but no matter the energy source, using the Fischer–Tropsch
> process or similar, you would always release large amounts of CO2. I would
> love to be wrong about this. Any chemistry gurus out there? -Kelly****
>
> ** **
>
> ** **
>
> Kelly, the easy way to do this kind of analysis is to look at the energy
> content of 96 grams of carbon (from coal) vs 116 grams of octane, which is
> how much octane could theoretically be synthesized with the 96 grams of
> carbon.  Then you must make up the energy difference by some means, and you
> need to supply the hydrogen by splitting water molecules.  ****
>
> ** **
>
> Thought experiment: imagine you have an unlimited supply of cheap
> electrical power that you can’t really use, and a pile of coal, and that
> you need to make octane from the coal.  The answer is to use the Fischer
> Tropsch process.  The South African plant burns coal to make the power the
> traditional way with a coal fired Rankine cycle, then uses the power to
> convert coal to liquid fuels.  This uses a lot of coal to make just a
> little Diesel and octane.  If you had a lot of wind and solar power, and
> you were using the FT process primarily as a load leveler and as a means of
> energy storage, you get something like the thought experiment I proposed:
> when you are making more energy than you can use or ship elsewhere, that
> energy becomes practically free.
>

Ok, I think I'm following along... but if all you need is energy and raw
materials, why start with Coal? Why not start with CO2 sucked from the
atmosphere (should make the greens happy) and H2O (for the hydrogen) also
sucked from the atmosphere? Yes, you have more latent energy in the coal,
but if the energy is really free, then why not just create it from the
atmosphere and bag the whole disagreeable matter of mining coal in the
first place? You might even be able to produce liquid Oxygen as a nice side
benefit.

****
>
> If we use wind and GB solar to convert coal to Diesel, the factory will
> have inputs of water, coal and electric energy, and have outputs of octane
> and oxygen.
>
> **
>

I know that the chemistry works. I suspect though that what I'm proposing
has astronomical energy costs associated with it that are not borne by the
FT process.

-Kelly
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