why clean coal doesn't scale

Coal is basically solid carbon (well brown coal isn't, but it's near enough). If you burn it you get CO2, replacing 12g/mol with 44g/mol. So it gets nearly 4 times heavier. But that's not the bad bit.

If you want to store CO2 you have two choices - dry ice or compressed gas/liquid. Nowhere on earth is cold enough to store dry ice in the quantities we're interested in, and man made storage facilities for storing billions of tonnes of CO2 annually are just asking for disaster (ask the people of Lake Nyos, Cameroon what happens when large amounts of CO2 escape).

Gas is a possibility, but the only practical place to put it is in subterranean gas tight pockets. The majority of these are old oil and gas wells. But there is a lot more coal than there was oil and natural gas. And gas is less dense than solid. And not all wells are suitable. So eventually we will run out of space.

(and that's assuming you can make it cost competitive with sources such as solar, wind and nuclear, which are already biting the heels of coal electricity)

Comments

(07:09:42 PM) bulwynkl@njhurst.com: coal - brown coal is 60-70% water. It's ground up, more water added and pumped to the furnace, dried a bit using waste heat and sprayed into the furnace. Wet coal has around 4MJ/kg, dry coal has 24MJ/kg If the coal industry wanted to reduce green house gasses by a factor of 4-6, they'd dry the coal before using it. the reason they don't is because it costs more in infrastructure and ongoing costs than the energy is worth, given it costs around 1c/ton to mine.why does it cost money to use waste heat? because heat exchangers are increasingly less efficient at lower temperatures (sub 200oC). the thing is that $30/ton CO2 carbon tax dramatically changes that costing.

the other thing that really gets me is that if one looks at what industry is most likely to be able to implement solar thermal power, it is the coal/power and petrochemical industry

next point.... if I had several billion tons of pure CO2 at my disposal I'd be making water gas using solar thermal heat and hence petrochemicals.... as far as I'm concerned the worlds liquid fuels market is currently up for grabs to whomever gets in first. odds on australia will miss the boat again.




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