capturing CO2 from a rocket mass heater

Ok i'm new to all this, but i absolutely love all the things i'm learning. what i was really wanting to know is: Is there a maximum length of exhaust pipe for a rocket mass heater? I was wanting to channel the CO2 through an algae grower similar to this one i found on line at http://www.inventgeek.com/Projects/Photo-Bio-reactor-V2/OverView.aspx Is this even possible? I just think it's a shame to release all that CO2 in the the atmosphere when it could be growing algae that is super healthy for you. I got a couple of ideas as to how to pull this off, but in input of ideas would be great!

CO2 released from fermentation can be used wonderfully for plant/algae but I don't think that exhaust from a rocket will be clean enough. Can algae handle CO not to mention the plethora of other compounds that will be present in the exhaust at different times/stages/conditions? Perhaps some small scale experimentation is in order before too much investment in plannning and construction. I appreciate the approach of not wanting "waste" so don't let my doubt get in the way of your mission. Please share your results for us fellow "gleaners". Canyon

Lasse Holmes wrote:CO2 released from fermentation can be used wonderfully for plant/algae but I don't think that exhaust from a rocket will be clean enough. Can algae handle CO not to mention the plethora of other compounds that will be present in the exhaust at different times/stages/conditions? Perhaps some small scale experimentation is in order before too much investment in plannning and construction. I appreciate the approach of not wanting "waste" so don't let my doubt get in the way of your mission. Please share your results for us fellow "gleaners". Canyon

As far as the algae handling other compounds, I believe they can but not sure you'd want to eat it then. But it was also my understanding that rocket mass heaters only released CO2 and steam, with a little smoke at the beginning, according to http://www.richsoil.com/rocket-stove-mass-heater.jsp I'm just basing my idea on theory, i have never built one so i'm totally speculating.

Ok here is a ruff idea of my plan.

I know nothing of the RMH, except for what I saw in the clips. But, my thoughts would be that the bubbling co2 through water would restrict the flow of the exhaust, and from what I saw in the clip the exhaust isn't flowing at a high speed or pressure. Not like a wood stove.

So my concern would be that the draft wold be highly affected and could back up into the living area. I don't think it would be a safe idea.

Bob Doyle wrote:I know nothing of the RMH, except for what I saw in the clips. But, my thoughts would be that the bubbling co2 through water would restrict the flow of the exhaust, and from what I saw in the clip the exhaust isn't flowing at a high speed or pressure. Not like a wood stove.

So my concern would be that the draft wold be highly affected and could back up into the living area. I don't think it would be a safe idea.

What Bob said. ---- A simple compost heap inside a greenhouse where the algae grows would be a simple and safe way to elevate CO2 levels. You could raise rabbits, chickens and even worms. All emit CO2.

love the idea of creating extra co2 in the green house would having a rocket stove under the compost pile help with the decomposition ?

Lassie and Kendra : W.o.w., there is a lot of conjecture here for projects and projects growing out of projects ! The link was interesting and was further proof of concept that I
saw in a Science video hosted by Alan Alda of M.A.S.H. fame, It showed a collaboration project between 'a' University and a Fossil Fuel Fired Power Generating Station where
they were using the CO2 and bubbling it through very similar photo bio-reactor algae tubes !

Some 'Rocket Mass Heaters R.M.H.s' are made with a exhaust gases diverter to warm up the R.M.H., and the chimney 1st. Like most Masonry Stoves and high end Wood
Stoves. When the shortened system is up to temperature, the diverter is moved to the second position, and the hot exhaust gases and its heat energy is then sent through
the thermal Mass in all three cases! An R.M.H. with a diverter will deliver a cleaner exhaust stream to a 'Bell' located just be for the final vertical chimney ! This would be the
best place to take off any gases that you would want your pump to bubble through your photo-bio-reactor

Kendra : Were you hoping to get a green compost, or green fertilizer ?! Unless you were to feed your algae to a biogas reactor, the amount of Methane created by decay of
the Algae and released to the air would defeat any environmental benefit from CO2 Trapping ! Collecting and then burning the methane in our kitchen would give us two bi-
products of our digestion a great Compost tea and an aerobically digested sludge at the bottom of the tank !

Dale : Same story here, If we had a bio-gas reactor inside your greenhouse it would provide a large amount of thermal mass, equal to most Aquaponics set-ups, again we
would gain Methane, Compost 'Tea', = to the amount of slops fed to it every day, and again the slurry at the bottom of the tank !

True fermentation at levels that would produce significant amounts of CO2, would ( I Think! ) be very labor intensive, the need for cleanliness would be extremely high, other
wise contamination would result in the production of vinegar and shut down two systems ! Sounds like you would need two clean rooms !

It would make a nice College level test of how acidic we could make the sea be for we further screwed up our planet !

More and more I am reading about small animals raised in green houses with success, it seems worth a Forum Thread !

Dale : while this could work, we would need to be able to divert needed heat to and away from the compost and very carefully monitor moisture content to keep the compost
working, again someone needs to decide how important the use of produced Methane is to the system and the environment !

For the Future/Good of the Craft ! Be safe, keep warm ! As always,your questions and comments are solicited and are Welcome ! PYRO-LOGICALLY Big AL

First let me say that piping the exhaust from a RHM into a closed, human occupyable space is dangerous. Take steps to protect yourself, and anyone that might be able to get in. Second, the volume of CO2 that a RMH would output is enough to kill plantlife, as concentrations beyond 1200 PPM of CO2 is increasingly toxic even to plants, particularly during nightime when they are consuming oxygen and not CO2. That said, concentrations up to about 1000 PPM are extremely helpful, so long as the partial pressure of Oxygen is still around 160 mm of mercury, or about 20% of atmospheric pressure at sea level. One way of jacking up the CO2 in a closed container (the alge columns as depicted in the diagram) would be to place a bubble pump, such as a common aquariam pump, inside or near the outdoor RMH exhaust port. This would allow the pump to import additional CO2 while the RMH was in use, without inhibiting it's ability to get fresh air when the RMH was not in use. Be careful, however, because if the pump only has access to CO2 when the RMH is in use after dark there might not be enough oxygen in the air supply to support the alge's own metabolism when it's not able to make it's own oxygen rich environment. CO2 doping of the alge columns after dark could kill the alge.

A RMH is designed to burn fast and store the heat for a long time. For this, you do not want a fast burn, so I don't think a RMH is the best fit for this project.

Tom OHern wrote:A RMH is designed to burn fast and store the heat for a long time. For this, you do not want a fast burn, so I don't think a RMH is the best fit for this project.

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Actually this is correct - and also "could be inaccurate"
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True the sheer volume of CO2 produced is high...
But if you build a large enough of an algae reactor - then the CO2 requirement could actually match the CO2 output...
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I would be more concerned with the exhaust temperature more than the CO2 volume.
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As for the issues of venting into a restricted space (ie the Algae reactor tubes - I assume via air bubbling stones): This can be overcome by adding a collection box with inlet fans to assure that you get a zero or slightly negative pressure at the rocket heater exhaust. Technically, this is feasible, but in practicality your restrictions/problems will be due to the fact that you must exhaust the gasses collected at a rate near or equal to collection rate (kinda like using a ballon to store gas not used - if you don't use enough of the gas the balloon will eventually grow too large and burst - not good...).
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I like the idea of excess CO2 going into a greenhouse - but see the problems with "enclosed spaces and oxygen displacement". It is never a good idea to exhaust any combustion exhaust into an enclosed living space. While from a physics point the argument could be made that Algae production could be scaled to provide near absolute conversion of CO2 gasses to O2 - it is never dependable. And with that said - it would only take one glitch in the process to create a catastrophic disaster.
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Still I like the concept.
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Since I am actively involved in researching and developing CO2 scrubbers for enclosed living spaces - I will definitely be looking into this further.
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I like Algae reactors, and I like the use of plants in living spaces to help keep the air more manageable. Even NASA has long struggled with the issues of CO2 production in enclosed living environments (ie SkyLab and the International Space Station), and has long sought out a non caustic chemical alternative. Too bad an algae reactor is way to bulky and heavy - we could chuck a few up on booster rockets and help resolve the issue (just poking fun - ya gotta see the humor???)
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Still - necessity is the motivation of all useful inventions. Should someone here actually solve the issues with 1) exhaust Temperature, 2) Exhaust volume and 3) conversion efficiency I do not see why it wouldn't be a $Billion development.
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Just my take..
Dave R. Mason
Arizona BioFuels Research
Phoenix, Arizona

I found this post when I was googling 'capture co2 from a rocket stove'.
Good thing someone has thought about it already
I think it's a great idea.
the exaust from a well built rocket stove will be just CO2 and water. so no problem with tars, methane or any other gases.
the thought of capturing the CO2 came when I was watching this video.
the inventor replaces the insulation of the stove with wood shavings and has them pyrolized for char. The heat generated also doubles because the gases from the wood shaves are being burnt.
anyway, I thought to myself, everything is being recouped: the heat, the char, the gases... what about the CO2? how could one recoup that CO2 to use in a greenhouse?
My idea was to compress it and uset it after. the idea exposed here is to make it cicle through a algea reactor.
anyone with any idea hot to capture by compressing it?

thanks,
Iz

maybe also have the exhaust cooled so we can recoup the H2O and compress only the CO2.

Wow lots here. Surely someone has tried pumping their CO2 Exhaust out of their house and into their greenhouse?

Oh well, that will teach me to not refresh my tabs.

Great ideas seem to be popular around here.

Dammit! I thought I'd read everything here on this topic, then find your reply after I've posted my bit about piping the exhaust to a greenhouse.

That said, no one replied to you, so perhaps there's still hope for the idea...

Ernie, Erica and I go into extreme detail on why it is a terrible idea to harvest CO2 from a rocket mass heater for a greenhouse in this podcast: https://permies.com/t/18871

paul wheaton wrote:Ernie, Erica and I go into extreme detail on why it is a terrible idea to harvest CO2 from a rocket mass heater for a greenhouse in this podcast: https://permies.com/t/18871

What if it could be filtered? In a similar way that methane is filtered after leaving the biodigester? I'd like to use it to "fill" long term food storage containers.

re-posting from the podcast thread (and btw it's in part 2 of that podcast, not part 1):

now that i'm more up to speed on the "why not to vent rocket CO2 gasses into a greenhouse," I'm going to ask, "what about venting rocket CO2 gasses into a greenhouse?"--and, specifically, what if you did it in a more minimalistic, Fukuoka-y way? you just let things take their course.

Could this be made in a way that is discipline-free, safe, leaky, quite open to the outside but capturing a bit of the gas closer to the point of exit?

Could it be a greenhouse that is only growing algae or dinosaur plants--i.e., whatever DOES like to grow under these (admittedly weird, non-natural) conditions?  

Here's my thinking:

--discipline-free: there are certain routines that people will tend to follow, and one of them is making coffee in the morning.  (I don't, I start my day off with chocolate, but that's a topic for another thread).  If there's a particular rocket stove for making coffee only--ie, it has the coffeemaker attached to it in a way that can't really be separated from it, maybe a chain--the people will make coffee in the morning on _that_ rocket stove only, and so you'll get extra boost of CO2 in the greenhouse/halfway greenhouse thingy every morning, not at night.  The other rocket stoves for lunch and dinner won't vent into the greenhousy thing ever, only the coffeemaker one.

--safe/idiot- and guest-proof: there is no way to get into the greenhousy thing except by climbing a ladder, crossing a moat filled with crocodiles, etc., and the only reason you ever go in there is to harvest algae out of it or something of the sort.

--easy: dinosaur plants, a completely non-technical term I am making up on the supposition that at one time there were plants or plant-like beings that lived long before there was any noncombusted oxygen in our environment whatsoever, such that they can thrive under any and all conditions, or at least get by under all conditions.  I tried to grow duckweed for some quail...for a friend...but all I got was algae.  So, I figure if it's even easier to grow than duckweed, it's easy.  It's almost just a problem rather than a solution.  So I am thinking that you just let whatever grows in a tub of water grow in that tub of water, and be unconcerned about what it is, and something good has to come out of it in the yield of carbon capture/energy you can put into use as fuel.  

--open: I understand that a greenhouse generally has to be fairly well sealed to be of much use as a greenhouse, but since Paul's doing his truly passive greenhouse that means I get to do my truly passive greenhouse.  I think mine just freezes at night and starts up again in the morning when the algae or the whatevers thaw out.  It's up on the roof, remember, by the chimney, so of course it doesn't have any geothermal help.  It may stay frozen on cold days too, but so what if it misses a few, it's just trying to capture some of the carbon, not necessarily get every last drop.  

--soot: the first few minutes of the burn aren't clean, but once it reaches temperature there's a passively-opened valve that responds to the presence of heat only.  If it fails, no worries, then you're just not capturing that carbon but venting to the sky as before.  If it succeeds though it diverts some of the carbon dioxide-water stuff into the algae greenhouse. Or maybe it's an active vent but you have to stand there holding a handle up to keep it open--if you let go (or even try to get around it by leaning a heavy object against the handle) it's just going to fall closed again.  You can stand there and recapture your carbon while drinking your coffee and chatting, but the second you step away, back to venting to the sky as usual.

Downsides I can see to this--the carbon could sink down to the house below.  CO could.  Mold.  Mold is OK in that greenhouse since no one goes in there except to harvest.  

what if you forget to harvest?  I guess it eventually gets overgrown with something, and you've got broken glass falling on your roof.  Maybe better to use homemade bioplastic instead of glass.

Well, if a tiny ad can defy gravity, why can't the power of half-assed-ness defy dangers aplenty?

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or what about a TEFA instead of greenhouse--open-air greenhouse-ish thing?

could an algae thing be a reasonable transitional technology--that is, not as bad as a solar panel in terms of manufacture/sourcing of materials and able to lead to electricity supply?