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CO2 scrubber for power plants

Reducing CO2 emissions from power plants using lots of green goo
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(+1, -4)
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There's a lot of fancy talk (at least here in the US) about "Clean Coal," which basically means coal-burning electric plants that have the bulk of their emissions cleaned up by a variety of devices collectively known to the great unwashed (myself included) as "scrubbers." This means that almost all of what is released into the atmosphere consists of carbon dioxide, which, as we all know, may or may not be a primary contributor to global warming (I'm not about to launch into that argument here). I propose developing a CO2 scrubber by installing giant banks of vertical cells containing tons upon tons of CO2-gobbling algae, which could be specially bred if no suitable strain already exists. Then, using technology available at any reputable fish store, just bubble the gas up through the sludge. What emerges at the top should be mostly oxygen. Run the banks in rotation so they can be shut down and cleaned as they become over-populated, and breath in the cool clean air while you try to come up with better ways to generate electricity than burning #@*!ing coal!
Alterother, Jun 26 2009

Baked 1 http://www.csmonito...11/p01s03-sten.html
[cowtamer, Jun 29 2009]

Baked 2 http://www.biofuels...-using-algae-broth/
still a cool idea [cowtamer, Jun 29 2009]


       You did, did you not, try Googling "CO2 scubber algae" or any of the other likely word combinations?
MaxwellBuchanan, Jun 26 2009

       It's not a bad idea, it's just not original to you.   

       Of course, if your algae absorb all the CO2 the coal puts out, you'll end up with an equivalent amount of algal biomass. To give you an idea of the scale, even when it's been dried down it'd weigh more than the coal, since it will contain a lower proportion of carbon. This should suggest to you that you'll need an awful lot of horizontal space to collect enough sunlight for the algae to process that CO2.
Loris, Jun 26 2009

       //even when it's been dried down it'd weigh more than the coal//
yeah but then you can burn it for fuel :) (really)(sortof)
FlyingToaster, Jun 27 2009

       That was implicit.
The point is, the amount of land you'd need to gather sunlight would be pretty big to cope with any decent-sized power-station.

       Unsurprisingly, people have done work on this already, as a cursory search would show. My impression is that there are several other issues to overcome, but that it might in future work as part of a micro-generation strategy.
Loris, Jun 27 2009

       There is also waste heat, as well as waste CO2. You could convert the waste heat to something a biological entity could use in trapping the carbon.   

       However, a team here in SA pioneered this Algae-type CO2 sequestration and sold the tech to the 'States, so it is baked. I don't know if it is widely known to exist. It also apperently doesn't work too well.   

       Converting the CO2 to oxylic acid, and then forming a oxylate (I suggest calcium oxylate for ease of use and calcium costs) with the waste heat might allow you to grow some form of fungi in a medium, thus eliminating the need for sunlight, therefore more density per acre footprint . And you already have the moisture and heat.   

       However the extraction of heat from the system may not be as efficient as cooling towers, so you need to do some work on that as well.
4whom, Jun 27 2009

       Here is my decision tree for whether something is widely known to exist (WNTE).   

       Is it something I've known
to exist for a long time?----yes---> WNTE
\---->Not WNTE.

       Hope this helps.
Loris, Jun 29 2009

       //just bubble the gas up through the sludge. What emerges at the top should be mostly oxygen.//   

       If this worked, you could then burn the sludge in the oxygen and redo the entire process indefinitely. So obviously, bad science. What you need in addition is a tremendous amount of sunlight to make this work.
ldischler, Jun 29 2009

       invention: swamp.
WcW, Jun 30 2009

       //see you have studied Microsoft documentation deciduously.//
What, until the leaves all fall off?
gnomethang, Jun 30 2009

       You can always store them in the page file ...
8th of 7, Jun 30 2009

       As others have pointed out, light is the key ingredient, so you would need vast areas of panels or shallow ponds.   

       A useful synergy is that, in a closed system, nitrogen could be excluded, such that the power station uses nearly pure oxygen, while the algae use nearly pure carbon dioxide, increasing the efficiency of both processes (assuming that algae can be found or engineered to thrive in nearly pure carbon dioxide).   

       It is fairly widely known to exist. I've heard politicians discuss the relative merits of geo-sequestration versus the use of algae to deal with carbon dioxide.   

       I think the best solution is to stop overpopulating the planet, and stop defining our lives by how much crap we consume. The attitude that it's alright to live a profligate lifestyle as long as you stick the carbon back in the ground is myopic.
spidermother, Jun 30 2009

       While I am all in favour of sustainability and ecological responsibility, I have to disagree with [sm].   

       Surely it's a good idea to spend time and effort working out how to do the stuff you enjoy while ensuring you don't harm other people/lifeforms/systems, rather than working out how little of what you want to do you can?
kindachewy, Jul 01 2009

       Also, would just like to point out prior art in that this was about the first idea I ever came up with, following learning about photosynthesis aged about 9.   

       I designed a fine 3D-mesh for growing algae on. The mesh included integrated uv-light emitters, and would be fitted inside a scuba-style tank to re-generate oxygen from waste C-O2. Got really p'd off when I found out about re-breathers.   

       I still reckon this will be a critical technology for long term space travel, seeing as algae have the added benefit over chemical scrubbers that they can be both self replicating and edible.
kindachewy, Jul 01 2009

       sp. WKTE
Twizz, Jul 01 2009

       [Twizz] Loris denoted //whether something is widely known to exist (WNTE)// Therefore WNTE becomes arbitrarily assigned, in this case to "widely known to exist". [Loris] could have chosen x or a for example. So technically it isn't an spelling error.
4whom, Jul 01 2009

       We are really concentrating too much on photosynthetic processes that need direct access to sunlight, as I have said before.   

       Long before our planet had true photosynthetic converters, it had all mannner of organisms converting whatever available energy to stored energy. Some of these "living fossils" can be seen at the deep undersea vents, although CO2 seldom forms part of these processes. Rather serendipitously, we have fungi on the surface of our planet that operate in the dark, and yet can convert CO2, in certain forms, into stored energy. Give them a bit of moisture, and heat (which is already waste heat in coal fired power stations) and viola! My only worry is that they can't cool (take energy from the system) fast enough.
4whom, Jul 01 2009

       I'm strongly in favour of reducing the harm done by our activities, by use of algae where appropriate. I guess what I mean is that damage is roughly [number of people] * [consumption per person] * [damage per unit of consumption]; we seem to want the first two to increase without limit, and hope to save the planet simply by reducing the last, which I suspect will be ultimately futile. A small population with modest needs could live sustainably even while burning coal without carbon capture but a large, growing population with growing demands will outstrip the Earth's carrying capacity regardless of technology and severely damage itself and the planet. It's a mathematical certainty. Not a reflection on your idea, just an excuse for a rant.   

       [4whom] I'm not sure what the fungi would do to the oxalate; wouldn't they just metabolise it and release carbon dioxide? I'm not aware of any form of fungal metabolism that doesn't produce carbon dioxide; they are heterotrophs, like animals, and get their energy by breaking down carbon compounds.
spidermother, Jul 01 2009

       [Spidermom] You describe the petri-dish syndrome. I agree with that. There are a few ways to solve this. 1) ncrease size of petri-dish. 2) Decrease size of population. 3) Increase efficiency of individual/population per resource. I think we all know we have to go for 3).   

       From Paul Stamets transcript:   

       //It's possible because the mycelium produces oxalic acids, and many other acids and enzymes, pockmarking rock and grabbing calcium and other minerals, and forming calcium oxalates. Makes the rocks crumble, and the first step in the generation of soil.   

       (slide of chemical models of oxalic acid (C2H2O4; HOOCCOOH) and calcium oxalate (CaC2O4))   

       Oxalic acid is two carbon dioxide molecules joined together. So fungi and mycelium sequester carbon dioxide in the form of calcium oxalates. And all sorts of other oxalates are also sequestering carbon dioxide through the minerals that are being formed and taken out of the rock matrix.//   

       I saw this about a year ago. I actually I thought I messed up the bit about oxylates. It turns out this is not a frequent behaviour of all mycelium, but there are those that do it, and the process can be seeded, by elemental calcium and not rocks per se.
4whom, Jul 01 2009

       Okay, you all caught me: I did not follow the WNTE protocol (which, yes, I usually do). I was being lazy.   

       Why isn't it WKTE? Just occurred to me.
Alterother, Jul 01 2009

       It isn't WKTE, because it doesn't actually fucking work. Every coal burning, waste heat emitting, CO2 spewing plant would have one, or several of these, if it did. Why on earth would there be cooling towers, if something more efficient extracted energy and sequestered carbon?   

       As I said earlier, this tech was explored by some. It was sold off to the US. Now unless you are some conspiracy therorist who thinks the government are controlling your mind with emitted CO2, the conclusion is:   

       it don't work so good.   

       The reason any photosynthetic medium can't do this is, as stated by others, the lack of exposure to sunlight per meter squared. You can get rid of CO2 by metres squared but you need vast tracks of land because you are creating it in metres cubed. That is one order of magnitude out. Biologists won't even give you that margin of error.
4whom, Jul 01 2009

       Grow-lights! Oh wait...   

       sp: tracts of land
BunsenHoneydew, Jul 02 2009

       /If this worked, you could then burn the sludge in the oxygen and redo the entire process indefinitely./   

       Yes, that is how it would work. It is not a perpetual motion device because you are inputting sunlight energy.   

       /You can get rid of CO2 by metres squared but you need vast tracks of land because you are creating it in metres cubed./   

       "Doesn't work" is not the same thing as "impractical because of immense spaces involved". Plus I am intruged by the equating by 4whom of "doesn't work" to "sold off the the US".   

       I do like 4whom's switch away from sunlight. But not to fungi. Too fussy, and require oxygen and a bunch of other stuff. Anaerobic chemoautotrophs are what you want. No need for sun. They could use a metal salt instead, and some phosphorus and nitrogen. They will make everything they need. The bioreactor could have 3 dimensions and so use meters cubed instead of meters squared. One could build this in a big swampy column.
bungston, Jul 03 2009

       [bungston] I did not mean to equate //does not work// to sold of to suckers, err, the US. The tech IP was bought in its infancy and was presumably scalable. It turns out it wasn't, unless you have a consipracy theory to prove otherwise. This was not intended to show the US in a bad light. They took a bet, and it didn't work. However it has sparked some interest in maximising efficiencies from the algae based mechanisms.   

       Also, I was trying to say "does not work economically", by virtue of large infrastructure necessary, and that the sequestering infrastructure is removed by one order of magnitude from the producing infrastructure. I am not saying doesn't work *at all*. Of course pumping CO2 into algae exposed to sunlight will convert *some* CO2 to carbon that is fixed in the organism and to oxygen that is fixed and/or released. Whether that becomes viable are not, is a big question. Answered by the fact that no-one is doing it...   

       I don't view fungi or myecilium as pernickety. That are actually pretty ubiquitous. They are not at all as fussy as people think. Sure, the ones we like to eat are fussy, but that does not apply to all. I do like the idea of chemotrophes or chemoautotrophes, but they generally rely on chemistry that enjoys more energy than CO2 can provide, given that there are no other energy inputs.
4whom, Jul 03 2009

       4whom - You will not hurt my feelings by observing that there are Americans who are suckers and chumps. This population is a pillar of American society. We all take turns participating as members.   

       But the matter at hand - the chemolithotrophs get their carbon from CO2 but their energy from elsewhere. Unoxidized iron is a candidate iron source and is a byproduct of industrial civilization, although scrap iron does have some worth. Iron also has the advantage of having an inert end product (rust). These critters need nitrate and as it happens this too is a waste product of hog and chicken farms and other large scale animal raising operations.   

       So: the coal plant would be built in proximity to a hog farm or other steady source of nitrate. Scrap iron would arrive by rail as the coal already does. CO2 fixation would occur in a large tank of iron enriched hog waste. Products would be nitrogen gas, rust and bacterial biomass.
bungston, Jul 03 2009

       [bungston] you may have noticed that I enjoy the thought of chemotrophes, but don't enjoy the fact that they derive energy from sulphitic (or sulphur based) reactions that contain more energy than carbon reductions.   

       However, I do remain a fan of carbon sequestration by fungi or by "chemophiles", as they do not need sunlight, and the power stations are producing waste heat/energy anyway.   

       You go with bacteria (good call) I go with fungi. Point being we both agree that photosynthetic processes are an order of magnitude out.
4whom, Jul 03 2009

       Nice idea, in that it utilises photosynthesis, the most effective reaction we can use to scrub C02 from the atmosphere. In my opinion, we should rather reduce deforestation and should still use this space for absorbing solar energy, but for solar power plants. This will be far more effective as we are not stuck with the problem of hundreds of tonnes of stored CO2. This algae farm, or bacteria farm, will be a biologial nightmare! We will be reducing biodiversity to make space of a single species. We will create a monopoly. This is in effect, cashing in your Ferrari for a rusty VW. For every Km2 of forest we save, we build an effective Km2 C02 scrubber. Let nature do its job, it has 4bn years of experience!   

       I may be repeating everything, haven't had time to read it all.
danman, Jul 03 2009

       Trees are so inefficient. People let them get away with it because they are so beautiful, and since that is also my modus operandi I do have some sympathy. But all that wood and wasted space - you got work to be done, you want efficient CO2 capture, it has to be unicellular critters. You want to smell the magnolias and see the bunnies hop - OK, then a forest is fine, but after work, please!
bungston, Jul 03 2009

       //Trees are so inefficient// but oh so cost effective.
FlyingToaster, Jul 05 2009

       Actually they are perfectly efficient, at being trees, for anything else they are a terrible compromise.
WcW, Jul 05 2009

       //Actually they are perfectly efficient, at being trees, for anything else they are a terrible compromise.//   

       In part I agree with you. The advantages, however, of using forests as CO2 scrubbers are huge and they far outweigh the minor lack of efficiency when it comes to CO2 scrubbing. Obvious advantages are that they look after themselves and help combat many of the problems associated with climate change such as the water cycle crisis and soil erosion, things which are essential for cost efficient agriculture.   

       I mean, with advances in technology and science at one point in time we will be able to just bypass nature, but at the moment it is a hell of a lot easiest and best to preserve and learn as much from nature as possible. As it stands, most of what we have invented comes from or has been inspired by nature. I may be in the minority here, but personally, I would rather we stayed in tune with nature-- it has done us pretty well up until now.   

       Photosynthesis is effective ENOUGH for life to flourish and to clean up the CO2 us creatures breath out in cellular respiration. There is no doubt about it (you can refer to any 4th grade CO2 cycle chart for proof). What I am getting at is that we should continue to utilise this to cancel out our waste C02 from cellular respiration, use extremely efficient sources of energy and allow a few more forests to grow to cancel out the extra CO2 emitted. That way everyone is happy.
danman, Jul 05 2009


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