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56 comments on A Discussion with Governor Brian Schweitzer

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Stuart Staniford on October 18, 2005 - 5:29am Permalink | Subthread | Parent | Comments top
I get the same answer if we assume the coal was pure atomic weight 12 carbon, and the H20 was molecular weight 18. However, that's not a good assumption, right - lignite is low grade coal with a lot of hydrocarbon junk in. According to this reference, lignite is only 37.8% carbon, 18.8% "Volatile Matter", and 43.4% water. If we assume the volatile matter has basically the right hydrocarbon ratio already, then we have 1.53 hydrogens per carbon in the balance of carbon+water. Now he only needs 0.47 hydrogens per carbon from the "colocated sources" (which I assume to be the rivers and lakes of Montana).
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Stuart Staniford on October 18, 2005 - 6:02am Permalink | Subthread | Parent | Comments top
When you consider some of the C is going to have to end up burnt to power the process, he may actually be not that far off balance. Interesting that coal which is so crappy from the traditional view of coal is actually more promising for CTL. Lignite sounds like it's basically compressed peat. Thus I guess that might explain why there's so much of it under the great plains (and Eastern Montana in particular). From the cactus in the picture, and this one here, the "colocated sources" look a little bit sketchy. But maybe this is not representative of Eastern Montana :-)
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TJ on October 18, 2005 - 8:46am Permalink | Subthread | Parent | Comments top
Lignite is peat that hasn't had enough time to turn into bituminous yet.  As I understand it, most power plant coal is lignite, because it's not particularly good for heating because of its high volatile content.

Using lignite may mean some types of gasifiers might not be usable.

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Nick Rouse on October 18, 2005 - 9:17am Permalink | Subthread | Parent | Comments top
Yes, the elemental analysis of dried lignite and subbituminous coal such as found in Montana here := http://pubs.usgs.gov/bul/b2144/carbon.htm
gives the percent by weight of dry material as :=
Lignite                       64-65% Carbon;  4.2-4.3% Hydrogen; 1.3-1.4% Nitrogen
Subbituminous coal   56-57% Carbon;  3.7-3.8% Hydrogen; 0.93-1.2% Nitrogen

This gives 0.76 to 0.81 hydrogen atoms per carbon atom of dried coal. If you add 40% water the hydrogen content rises to 2.1 to 2.4 atoms per carbon atom. This is indeed close to the theoretically required ratio.

The disadvantage is that the carbon content of the wet coal is 34 to 39%. If the yield figures for coal to liquid conversion usually quoted are for dry high carbon coal then the yields this per ton of mined material will be much lower.

The promise is for a clean process. Let us hope that things have improved a lot but I have memories of the gas works in the UK that provided domestic gas when I was a boy before the discovery of North Sea natural gas. They produced from coal a mixture of about 50% explosive hydrogen and 15% poisonous carbon monoxide piped to houses often with no safety cut-outs. A delay in lighting the gas lamps would produce a bang that would shatter the mantle and scatter uranium soaked silk ash in your face. The gas works always stank. The nitrogen would form ammonia and amines and combine with the sulphur dioxide to give a stench I still clearly remember. Promises will doubtless be made but I wonder if they will be kept.

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TJ on October 18, 2005 - 10:03am Permalink | Subthread | Parent | Comments top
Unlike using water gas or syngas directly, doing FT or methanation requires that you take the crap out or the catalysts don't work for long.  And at this point, there are no appliances or furnaces that would work on syngas alone.
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LJR on October 18, 2005 - 12:02pm Permalink | Subthread | Parent | Comments top
Where would I find EROEI figures for the Fischer Tropsch process?
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Joseph Somsel on October 18, 2005 - 3:34pm Permalink | Subthread | Parent | Comments top
Coal-to-Liquids processes are capital-intensive.  See:
http://www.eia.doe.gov/oiaf/servicerpt/erd/fossil.html

In fact, of the Hirsch Report alternatives, it is the most capital intensive of the options, at $66 billion for a 1 mbpd output.

This must take a lot of excess coal burning to drive the system since its mostly endothermic.

The hydrogen production nuclear reactors being discussed will need a 900 deg C process heat for the sulfur-iodine cycle to make hydrogen.  The R&D will focus on a reactor that can deliver that temperature.

Once you have that temperature, you can do carbon + water + heat = hydrocarbons + oxygen and get a product with higher energy density, non-cryogenic, non-volitile, and backfits into existing automotive/jet technology.

Hence, I see nuclear-assisted coal-to-liquids as more promising that a pure hydrogen economy although there will still be greenhouse gases generated at the end use point.

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56 comments on A Discussion with Governor Brian Schweitzer

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