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Comment by fromthestart | Hacker News Reader

Clean coal refers to scrubbing pollutants and possibly CO2 from emissions. It isn't necessarily bullshit.

Indeed, and to clarify "clean coal" isn't referring to cleaning the coal, it is referring to increased effort put into trying to reduce released pollutants when using the coal.

There was a hilarious quote from a while back where a politician referred to train loads of "cleaned coal" heading out of Montana which created a misunderstanding about what clean coal technologies are trying to do. There is no "cleaned coal".

(Aside, I believe calling those technologies "clean coal" is quite hyperbolic, but that is a separate issue)

Coal mines vary widely in the amount of impurities in the coal they produce. Low-impurity coal requires less scrubbing to meet a give emissions target. Sulfur is the worst of the impurities -- it becomes sulfuric acid in the atmosphere and is precipitated by rain, causing concrete to erode.

The cleaner coal is called Anthracite [0]. The dirtier coal is Lignite [1]. Lignite is usually cleaned, by heating it up to drive out the water so it burns better (and weighs less during shipping.)

[0] https://en.wikipedia.org/wiki/Anthracite [1] https://en.wikipedia.org/wiki/Lignite

It can refer to: "reduce oxides of nitrogen (NOX) and sulfur dioxide (SO2) emission"

This was a boondoggle near my hometown: sttps://en.m.wikipedia.org/wiki/Healy_Clean_Coal_Project

Sheetrock/gypsum board is another byproduct: https://www.buildinggreen.com/primer/synthetic-gypsum

There was a wave of flue gas gypsum emitting acidic gasses around 2009, eating through copper plumbing and wiring. This was in Florida.

CO2 still has to go somewhere. Carbonation, industrial gasses, into the ground, or into the air.

I'm skeptical of clean or green in any product name. It's more about marketing.

>There was a wave of flue gas gypsum emitting acidic gasses around 2009, eating through copper plumbing and wiring. This was in Florida.

sounds like https://en.m.wikipedia.org/wiki/Chinese_drywall rather than clean coal

My point was that clean coal can mean a lot of things and sometimes making one part of a product lifecycle "green" just passes the problem down the supply chain.

In this case, scrubbing the flue gasses and recycling the coal ash resulted in toxic drywall. This isn't to say all drywall is toxic but it illustrates one illusion of something being clean or green.

There is no thermodynamically possible way to generate power from burning coal while also removing the primary product of the reaction from the effluent. Clean coal is, necessarily, 100% bullshit.

That's not true at all. You can, for example, sequester it by injecting it into the earth.

By default you would then end up with less energy than you started with

I think the idea is not to turn the CO2 back into carbon and oxygen, but to store it somewhere other than the atmosphere. That is not thermodynamically impossible.

>Clean coal is, necessarily, 100% bullshit

Necessarily = chemically and thermodynamically

It is BS because they never put anything behind it.

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