According to yesterday's paper, clean coal reduces greenhouse gasses. How come, since it releases CO2?

Answer 1

I don't know exactly what your paper is referring to as the above answerers indicate it only says cleaner. However there is a process called steam reforming which converts coal into hydrogen and CO2 (plus some sulphur and nitrogen compounds). The hydrogen can be separated and used as fuel for power generation whilst the greenhouse gas CO2 and the oxides of sulphur can be pumped deep underground and locked away. http://www.bp.com/genericarticle.do?categoryId=2012968&contentId=7019791 I saw somewhere that the cost of electricity produced in this way is about twice that achieved by the normal fossil fuel technologies.

Answer 2

I have to see the context of the claim, but it seems to me that if it is called clean coal it's because either it releases less CO2 or because it releases no CO2(I dont know how) when burned.

"Reduces greenhouse gasses" can be interpreted in two different ways. The most probable is that if clean coal releases less CO2, then it 'reduces the amount of CO2 that would be produced if regular coal was used instead'. This is not referring to the CO2 already on the atmosphere.

The other interpretation I find unlikely, which is probably the one that confuses you. If the amount of CO2 in the atmosphere is reduced by burning clean coal then it would have to release some other compound that once in contact with CO2 produces a 'healthy' byproduct. I bet this is not what clean coal does or we would have found the cure for Global Warming ;P

Answer 3

You're right, it's BS.

"Clean coal" has 2 meanings, depending on who you ask. To TXU and other utilities, it simply means burning coal the good old fashioned way, and then simply using aftertreatment to reduce sulfur dioxide and particulate emissions; doing this does not in any way reduce CO2 emissions, however. In other circles, "Clean Coal" means to burn the coal in a closed cycle process, whereby most or all of the CO2 produced during combustion is captured and then compressed and possibly liquified so that it can be injected underground or "sequestered".

The latter definition of Clean Coal is a "nice idea" in that CO2 does not enter the atmosphere, but is instead sent underground where it will "hopefully" stay there and not leak out due to seismic activity, etc. The other "nice" thing is that the injected CO2 can be used by petroleum companies to increase the amount of oil they can recover from a reservoir, and they will therefore pay the utility for the CO2 they use this way.

However, closed cycle processes are less thermodynamically efficient, and worse yet, the energy required to compress the CO2 (a LOT of energy) further reduces the net efficieny of such systems dramatically. This is precisely why it would be economic suicide at this point to try and run a utility based on a closed cycle powerplant. The only commerical-sized closed cycle powerplant (FutureGen) that is coming online in this country in the near future is largely a research project and not a true business endeavor.

In my humble opinion, as a Mechanical Engineer with a Master's Degree, is that "Clean Coal" is mostly a load of garbage. I mean, clean coal is better than dirty coal (a' la China these days), but that's like saying crack is healthier than crystal meth. Windpower is simply hands down the safest, most reliable, most economical (4.5 cents/kWhr for wind versus 3.5 cents/kWhr for coal) replacement technology for coal. North America has plenty of wind reserves to meet current and future demand, so I see these "debates" about Clean Coal is nothing more than red herrings and empty-headed political posturing.

If we humans want to survive for more than 200 more years then we had better get a clue and start installing more wind turbines.

Answer 4

Note that it says that it helps REDUCE greenhouse gasses, not help to get rid of them. When they say reduce here, they are referring to the amount that is released when burned. Clean coal is the name attributed to coal chemically washed of minerals and impurities, sometimes gasified, burned and the resulting flue gases treated with steam, with the purpose of almost completely eradicating sulphur dioxide, and reburned so as to make the carbon dioxide in the flue gas economically recoverable. So, while the coal will still release CO2, it becomes much easier to capture that emission than with normal coal.

Answer 5

"Clean coal" "reduces" greenhouse gases because the coal is processed to remove elements such as sulfur and nitrogen, so oxides of these elements are not present in flue gases. Damage to other parts of the environment by the "cleaning" process are ignored by proponents.

BTW, complete combustion of any hydrocarbon yields nothing but "greenhouse" gases: CO2 and H2O.

Answer 6

As was already mentioned, this is saying that Clean Coal reduces green house gasses. This reduction is because this form of energy production yields more Kilowatt hours of energy per unit of pollutant.

Answer 7

CO2 is soluble in water ,just like your soda water. They have what is called scrubbers in the stacks and about all that escapes is a little CO2 and water vapor. 99% of all pollution is washed down the stacks. They have the coal plants all over New Mexico resulting in some cheap electricity.

Answer 8

Oh it "reduces" it huh. By how much? Sounds like one of those old commercials for detergent that makes your shirts "whiter". Whiter than "what" never being specified.