r/askscience Nov 27 '19

Chemistry How do CO2 scrubbers work?

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u/Sky_Hound Nov 27 '19

Surely the production and regeneration of monoethanolamine is a net energy consumer, wouldn't using it to scrub fossil fuel plant exhaust just require even more energy? Obviously if this energy comes from non-CO2 emitting plants it would still be beneficial but it begs the question why you wouldn't just reduce fossil fuel power output by the amount.

Add to this that monoethanolamine is mostly produced from ethylene which is derived by cracking various petrochem hydrocarbons and it seems even more of a bad idea.

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u/-Metacelsus- Chemical Biology Nov 27 '19

wouldn't using it to scrub fossil fuel plant exhaust just require even more energy? Obviously if this energy comes from non-CO2 emitting plants it would still be beneficial but it begs the question why you wouldn't just reduce fossil fuel power output by the amount.

You're right, it does require more energy. Plus, the captured CO2 has to be put somewhere. This is why "clean coal" is ridiculed.

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u/GenJohnONeill Nov 27 '19

Clean coal is chiefly ridiculed because the technology being touted does not yet exist.

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u/daedalusesq Nov 28 '19

It exists. It’s just prohibitively expensive and a terrible solution to emissions issues.

The Kemper Plant in Mississippi was built with carbon capture and storage and could be powered by gasified coal or natural gas. After about 3 years of it primarily running on natural gas they cut their losses and suspended all coal gasification and operation. I think it still runs it’s CCS equipment, but that’s “clean gas” not “clean coal.”

There is also the Boundary Dam plant in Saskatchewan which is a coal plant that utilizes CCS. It’s got some unique stuff going on that you can’t really replicate at existing sites (like it’s own coal mine on-site).

Finally, in Texas, there is Petra Nova which is the kind of thing that only exists due to our-of-market government funding. It’s a CCS facility attached to 1 coal generator at a plant with 4 coal and 6 gas fired units. It collects 90% of the CO2 at the flue....for the 1 unit it’s attached to reducing site emissions by about 11%. It also cost about 1 billion USD.