I was about to edit this article some more when I noticed the line in the introduction:
CO2 is still released into the atmosphere so "clean" does not mean carbon neutral, but sulphurous impurities can be dramatically cut using "clean" coal.
What Clean Coal Really Is
Since this is something I am intimately familiar with (I do IGCC development and engineering for GE) I will tell you what clean coal, as a term, really stands for. "Clean coal" is actually a combination, solely for political purposes, of two different concepts: IGCC and sequestering.
- IGCC (Integrated Gasification Combined Cycle) is the less-controversial-but-far-more-complex process of producing cleaner energy from coal though converting it to syngas, which increases turbine fuel efficiency approximately 40% and produces approximately 50% less overall pollution and 20% overall less CO2 emission.
- Sequestering, however, is a bunch of bullshit, but is the one most promoted by utilities (as IGCC is 20% more expensive than regular old "filthy" coal). The idea with sequestering is that, if you pump all the CO2 underground into coarse rock, it will stay there. Sort of like a ostrich burying its head in the sand. However, in reality, it usually will seep back up to the surface. It will also fuse with any underground water and change it into carbonic acid.
That, folks, is "Clean Coal" in a nutshell.The Goonie 1 07:49, 6 June 2009 (UTC)
Explaining My Lack Of Resources
Unfortunately, I cannot disclose most of my resources on IGCC and sequestering are classified by the United States Department of Energy as "Confidential" and "Export Controlled", and the other ones I have are GE proprietary information, so I cannot disclose the sources. Boy, do I love my security clearance, though.The Goonie 1 (talk) 03:10, 9 July 2009 (UTC)
Not an eternity
There is research into turning CO2 into an energy source in a way outside of conventional biofuels. If this becomes viable, I suspect that we might tap into the CO2 storage facilities as an energy source (kind of like how sometimes we sometimes turn nuclear waste back into fuel). This has the unfortunate draw back of not lowering CO2 in the atmosphere directly, but it might mitigate the amount of storage necessary as would also lower the consequences of a leak. I am largely ignorant on how both the storage process works and how the CO2 into energy conversion is going to work. Corpse in the bed (talk) 00:38, 6 October 2014 (UTC)
- opportunity cost wise
Some maths on carbon sequestration.
Some people really don't seem to understand how much CO2 burning things produces.
So let's do some maths.
First, what are we burning?
Let's imagine it's pure carbon. What happens when you react this with Oxygen?
CO2, that's what. Via the simple chemical formula
C+O2 ---> CO2 + energy.
Now the question is, how much energy are you getting?
A single C-C bond is worth about 347 kJ per mole. An O=O bond is about 498 kJ per mole. Meanwhile, the C=O bonds in CO2 are 799 kJ per mol.
Great, so for each C atom burned, we need to break an average of 2 C-C bonds. That's 794 kJ. For each O2 molecule burned, we need to break an O=O bond. That's 498 kJ.
So 799*2-794-498 = 306 kJ per mole. Great, so how much is a mole of CO2? 44 grams, 12 is the Carbon, and 32 is the pair of Oxygens.
So 1 kilogram of Carbon being burned yields 25.5 MegaJoules of energy, and 1 kg of CO2 is produced for every 6.95 MegaJoules obtained.
So how many MegaJoules does, say, the United States, obtain from coal? Well, only about 22% of the total. (Though about 69% comes from fossil fuels, including petrol, coal and methane). That means 22% of 10^20 Joules per year is produced, but 44% of that is consumed. 2.2*10^19 Joules is how much energy, half of which is waste heat, comes from American coal.
So, 2.2*10^19 Joules / 6.95*10^6 Joules kg means that American coal makes about 3*10^12 kg, THREE BILLION TONNES of CO2 annually.
So here's the problem? How do you practically sequester 3 billion tonnes Of CO2 per year? I mean, that's 10 tonnes per American.
But remember, CO2 is a gas. It wants to consume space. 500 liters for every kilo of it. Yep, the coal industry needs to try to bury 1.5 quadrillion liters of gas every year. That's a cube from sea level to where airliners fly of 1 atm CO2. Good luck trying to compress and bury that. As another comparison, imagine a layer of pure CO2 gas covering America 6.5" deep, and another, and another, each year.
sequestering section rewrite needed
I think that the beginning of the sequestering section exaggerates how hard it is to sequestor carbon since terms like woo and bull make it seem literally impossible rather than impractical and should probably have more technical information added to it. Vorarchivist (talk) 04:17, 9 September 2018 (UTC)