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| Bunbury |
 Posted: Fri Oct 26, 2007 9:24 am Post subject: Coal and greenhouse gases. |
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Forum Ph.D.
Joined: 26 Sep 2007
Posts: 777
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The world has vast reserves of coal located in China, the USA and other places that are importantly NOT in the Middle East. It’s inevitable that it will be used increasingly for power generation and for producing synthetic automotive fuels. The coal to liquid fuel technology is old. Nazi Germany produced motor fuels from coal; South Africa has been the technology leader since it was isolated from oil supplies by its apartheid policy.
This PowerPoint slideshow (apologies to PP haters) discusses how coal can be used responsibly.
http://www.princeton.edu/~cmi/events/2005/WilliamsWpm.pdf
In summary, a coal-based reduced greenhouse gas future is possible but only if it includes all of the following:
Coal gasification plus water shift
Combined cycle power generation using syngas
CCS – Carbon Capture and Sequestration
Biofuels from switch grass, perhaps sugarcane, other sources
Synthetic diesel or DME (dimethyl ether)/hybrid electric cars and trucks
Big Coal and Big Oil are planning dozens of major coal gasification projects. CCS (carbon capture and sequestration is always mentioned in proposals but is dependent on geography and geology, and it seems highly improbable that every new coal gasification plant will be designed with CCS in the final plans even if it’s there in the early proposals. The gasification technology is decades ahead of large scale sequestration technology.
The graph on slide 18 of 32 illustrates the problem. Without CCS every technology, however it may be spun, adds to the greenhouse gas problem unless it includes CCS. When you see ads for “clean coal” consider what it really means.
"There's an old saying in Tennessee - I know it's in Texas, probably in Tennessee - that says, fool me once, shame on – er - shame on you. Fool me - you can't get fooled again." G.W.Bush
You can only be fooled if you don’t have the facts. Bunbury |
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| Ophiolite |
| Posted: Fri Oct 26, 2007 1:02 pm Post subject: |
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Forum Radioactive Isotope
Joined: 25 Jul 2005
Posts: 4632
Location: Scotland
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Therefore one should campaign for sequestration programs rather than against coal gasification. Your post suggests you are in favour of the latter.
_________________
The Universe is not only weirder than we imagine it is weirder than we can imagine. J.B.S.Haldane. |
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| free radical |
| Posted: Fri Oct 26, 2007 2:17 pm Post subject: |
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Forum Masters Degree
Joined: 24 Sep 2007
Posts: 503
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I've recently learned a bit about some of the sequestration pilots that have been undertaken. Several of our colleagues have been involved in pilot studies testing the feasibility of sequestering CO2 at the bottom of the ocean. The results were unexpected. The CO2 that was sequestered at ocean depth created a localised, somewhat stable, pool of very acidic sequestered CO2 (carbonic acid, I assume?) The pH was between 4 and 5. The carbon did not diffuse.
This approach sounds like a very good way to kill ocean life in the areas where sequestration occurs.
A second proposal, involving fertilising the surface of the ocean water, successfully reduced CO2 immediately above the surface of the ocean, due to stimulation of algae growth. However, shockingly, no biologists were included in this particular pilot. Atmospheric chemists measured what they felt would be the relevant parameters for sequestration, and no measurements on the effects on the biosphere were included, as I understand it.
Other proposals, such as sequestering into terrestrial rock formations, have also been examined. I do not know any detals on these studies. |
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| Bunbury |
| Posted: Fri Oct 26, 2007 4:01 pm Post subject: |
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Forum Ph.D.
Joined: 26 Sep 2007
Posts: 777
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| Ophiolite wrote: |
| Therefore one should campaign for sequestration programs rather than against coal gasification. Your post suggests you are in favour of the latter. |
Hmm, I certainly didn't intend to suggest that. There's hardly any point in being "for" or "against" it. It's happening, so we'd better get over it. I am even working on a gasification project for one of the major oil companies. My concern is that the public is being duped into thinking "clean coal" is environmentally benign. It isn't unless the CO2 is sequestered. The project I'm working on is generic, in that a specific location hasn't yet been selected to build it. Sequestration is described as a goal in the project definition, but time will tell how serious the oil company is about this goal. I'm skeptical, and as a participant I'm more than a little troubled.
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| Other proposals, such as sequestering into terrestrial rock formations, have also been examined. I do not know any detals on these studies. |
This has been done for secondary oil recovery. Pumping the CO2 back into the ground pushes out more oil. It's a little different with power plants, which have to be relatively near the consumer, not necessarily near the right kind of geological formation. |
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