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Simple Algae Home CO2 Scrubber - Part 1

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I created this instructable to show how to build a simple algae based CO2 scrubber for home or apartment use. The basic design shown here will scrub its own consumption and approximately 24 pounds of carbon dioxide from the atmosphere every year. This is approximately the CO2 produced in the production of 17kW of electricity. This device may be scaled up to process larger quantities of CO2.

The carbon dioxide is consumed by the algae which release oxygen. In part I the scrubber consists of a 2 liter reactor vessel and a small aquarium air pump. The bottle contains a solution of water, algae and nutrients. Room air is passed through the bottles using a standard aquarium bubbler stone where the CO2 is absorbed by the algae and oxygen released.

In later parts this basic design will be expanded provide more flexibility and increased production.

Maintenance is simple and straightforward as any house plant. About twice a month I add a couple drops of liquid plant food. The color of your home scrubber may be kept at any desired color range by controlling the food. If the algae gets too dark for your taste simply wait until the color begins to lighten before feeding again, if its too light try adding another drop of nutrient or feeding more often to increase the population.

Once or twice a year its probably not a bad idea to clean the scrubber. Save enough medium from one of the lightest bottles to reseed them. Then empty them into your compost heap, the sink or the toilet and restart them using tap water and the reserved medium.

All that being said, let's take a quick look at the tools and materials we'll be using then we'll get started.
 
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bio-boy3 years ago
I am looking to make my household carbon neutral. I am intrigued by the solution you are suggesting. After other green initiatives such as increased insulation, my carbon foot print is around 10,000kg of carbon per annum.

If I understand what you are saying

1 2ltr bottle will consume 24lbs of CO2 PA or 10.88kg

So 1ltr will consume 5.4kg approximately. (Call it 5 kg to keep the maths simple. & I may not be able to achieve the same growth rates as you)

There fore to offset 10,000kg of CO2 I need 2000ltrs of water/algae/nutrients?

I have a large garden. At the bottom of my garden is an overgrown pond, (installed by the previous owner) its filled with leaves & other organic matter, witch I have recently dug out. It is south facing & gets sun all day long. After a quick calc I have determined that this has a volume of, a little over, 2100ltrs

Would this work either as an open pond or covered with some sort of clear plastic sheeting? If so what sort of size of pump would I need?

Thanks
James
1 way too get your house carbon nuetral is to go solar with deep / universal / golf / specailized batteries. then wired them up with grid tie inverters. if its done properly an well uill be able too stop your meter from turning at all.
egbertfitzwilly (author)  bio-boy2 years ago
Did you make any progress on this?
egbertfitzwilly (author)  bio-boy3 years ago
Sorry it took so long to reply, I had to sort out some information.When one moves from a tank to a pond a whole range of new possibilities opens up.

Breeding algae in a pond presents two challenges, light penetration and harvesting. With a tank based system harvesting is a trivial matter, with a pond based system one must deal with the issue of how to manage a 20 micron object.

The other challenge is light penetration. Sunlight will only penetrate to about 6 cm ( in terms of algae usable light ) due primarily to shadowing. So it is necessary to rotate the tank contents by some mechanism.

Fortunately there are at least two major studies that are worth considering as they provide a well thought out solution space.

The most recent is from the University of Alabama regarding the production of algae as biodiesel feedstock and the other is from the NREL Aquatic Species Program.

I've attached these two files to the instructable so you can review them. Please keep us informed of your progress and consider doing an instructable if you do something to make your pond an algae farm.

aashley648 months ago
hey I wanted to ask you how did you estimate how much amount of carondi oxide is been used up by the algae.. also i want to do carbon sequestation in a pond. plz give some ideas
hpetrow8 months ago
So if the pump can pump for example 50l/h and atmosphere has 0.033% of CO2. That would make only 114l of CO2 passing the device in a year. That would make something like 0.3 kg/year of CO2 passing the scrubber. So I guess most of the CO2 should come from the surface interface with atmosphere.

In that case isn't the design quite ineffective? The out flow of the air prevents the atmosphere to enter the bottle. Shouldn't the top be open and the algae solution have as much exposed surface as possible?

Feel free to point out if I have gone somewhere wrong with my thinking. Planning to design my own scrubber, so would be nice to know if my thinking is right or not before buying the materials for it.:)
I have tried a couple times to get algae to culture from samples from my fish tank (a freshwater tropical setup) and have yet to get any algae proliferation. Each time the bottle turns a nasty grey color and I get an off-white sediment that forms. I have tried aerating and conditioners to remove chlorine/chloramines and add plants food. Any ideas what I may be doing wrong?Thanks
egbertfitzwilly (author)  Prodiver2551 year ago
I have never seen the symptoms you describe. Have you tried with water from the tank? You should also be able to use water from a stream, pond or lake. You could also use bottled, distilled water.

If you are using liquid plant food remember a little goes a long way.
novice1015 years ago
This is a quick flow chart. The residual could be converted to charcoal (pyrolysis), and buried. (google Terra Preta )
AlgaeProcess.jpg
Could the resulting charcoal be used in turn to filter water in your fish tank? Or would it have to many other 'residual' ingredients to make it safe for your fish? Thinking on larger scale for smal home fish farm appropriate for prepping.
ebcat4 years ago
I am studying algae for a school project, I have cultivated some kinds of algae but, when I extract it from its habitat, they die. I thing the cause of algae die it's the turbulence of the air pump? it can be that?
egbertfitzwilly (author)  ebcat4 years ago
What kind of water are you using? Try filling your container with the same water you take your algae sample from. If your using tap water (or bottled water) let it stand for a day or two then boil it to drive out any remaining gasses. The container you fill from the natural source should get a good healthy growth, you can use samples from this to create other cultures. If your air pump to way too big for the container I suppose it might damage the algae. If so then using a larger container (like a gallon milk jug) might do the trick for you. I've attached a picture of another version I've got at home. This one uses an aquarium filter (without any filter cartridge) to aerate the water.
P1010222.JPG
Although this can work it is less efficient than your first model due to only the top being the suitable area of algae growth compared to your first filling the bottle. second of all if the algae gets sucked into the pump (if that were to happen) it might get too agitated in the mechanism it could die.(maybe put a finer strain cover on the end) Plus the aqua filter would seem to use more energy than an air pump. But yes it can aerate the water and that what I use for my ten gallon fish tank for aeration, and a good bacteria set up for filtration. ( i hate buying filters all the time). And also what is the suggested time to keep air pump on if turbulence is an issue (like for ebcat)
egbertfitzwilly (author)  OruKun4 years ago
Actually its much more efficient, the biowheel rotates the medium from the bottom of the tank up into the light (and aeration). Studies have shown that algae need only about 1X10-23 seconds to absorb a photon but about 6 seconds to complete photosynthesis.

Of course I remove any filter elements so the pump(s) merely rotate the water into the photic/gas uptake zone.

This particular pump is the same as the air pump I was using but much more effective in this configuration. Conceptually I think this is much better than the raceway pond for large scale configurations.

Since I don't have a fish tank I can't speak to what cycles might be appropriate. I use an 18/6 light/dark cycle which is optimal for the algae.
Using bio balls is a good way to give your algae I way to anchor down and remain more stable, you can always add more lighting with submerge able lights, just a thought. • • • Fuzzee Dee OUT • • • }~{ <> }~{ ^~^ :-> 
egbertfitzwilly (author)  FuzzeeDee1 year ago
Yeah, I was thinking LEDs on a wire rack with some capacitors so they fire a limited number of times a second.
Amazing the level of efficiency that can be achieved with a little effort.
"If your using tap water (or bottled water) let it stand for a day or two then boil it to drive out any remaining gasses."

I don't think the gasses are the problem here. I think chlorine might be the problem, and to fix that you must use a dechlorinator from your pet shop or pond shop. Old style chlorine will remove itself from standing water in 24-48 hours, but chloramines, now in use in most US city water supplies, is stable and will not remove itself from the water. Both prevent the growth of algae, bacteria, and fungi.

egbertfitzwilly (author)  chuckr444 years ago
Agreed.
OruKun ebcat4 years ago
ebcat, if you are worried about turbulance ask the suggested time for keeping the air pump on for aeration.
If your answer to ebger's suggestion is "I did all of that" the algae you may have gotten into shock with the new environment, thus if you are cultivating it from its habitat get some of the water from it before switching to yours.
And if the algae you extract still dies, its either unidentified human error or a weak organism  sample that is not suitable for your school project.
bigt46165 years ago
wait, my town uses ozone to clean the water(way more cleaner way) all it does is add oxygen to clean the water, so it should be safe to use, right, if not tho, theres a stream that runs by my house from a mountain so i could always use that. i was just wondering tho.
egbertfitzwilly (author)  bigt46165 years ago
Should be fine, I'd let it breathe for a day or two so that the dissolved excess oxygen can evaporate.
eh, im going to get it from the stream just in case. i somewhere that someone was doing this with water bottles, i think thats better to put it on a windowsill, im probaly going to do that and my pump has 2 ports, also my dad has a pond that he never cleans, so that should be crawling with algae. i also made a hydroponic system in my room last week. im feeling green this month, rofl.
k, i got the algae from my dads pond, its kinda clumpy and i turned on the pump and its just circulating arround. is that ok? also, can i put a timer on it so it only does is when theres light? cause they wont use photosynthisis at night.
egbertfitzwilly (author)  bigt46165 years ago
Yes, that should be a fine source of algae. A timer to turn off the light at night is also a good idea. You can probably run multiple bottles off of each port. If you run down to PetSmart you can find an aquarium manifold that will distribute air to multiple lines. Keep in mind that the bigger the pump the more power it uses. On the pump it should have somewhere the rated power in Watts. I use a pump rated at 1.8W (about 15kW/year). If you use a more powerful pump you may need to have some extra algae to consume the additional power. Also I found that when running multiple bottles from a single air line getting the back pressure correct in each bottle was critical. So fill the bottles and carefully adjust the opening to make sure everyone seems to be getting about the same amount of air.
You can get pressure balanced manifolds, but cost twice as much.
• • • Fuzzee Dee OUT • • • }~{ <> }~{ ^~^ :-> 
its a 3.5 watts so with another bottle on it, it should equal a little more efficiant than yours. im probably going to try to get 4 bottles. im kinda short for parts right now, im using a balloon with holes for a bubbler, i so need to get out to the store. rofl. and thanks for all the help.
egbertfitzwilly (author)  bigt46165 years ago
You probably want to get a bubbler stone. To maximize the absorption of gas from a bubble the optimum size is 3mm. Since aquarium air stones are designed to optimize gas transfer into the surrounding they come in at a good average size.
i know, i finnally got a chance to get to the store. i think its working but you really cant tell from the 2nd day rofl. btw, i got a timer at wallmart for 6 bucks! its a really good one too. i got it running from 6 to 6
egbertfitzwilly (author)  bigt46165 years ago
By third day you should be able to see a twinge of green, if you look hard and had a reasonably sized starter population. Under ideal circumstances the algae will double every 8 hours.
wow, i didnt notice it till now but there is alot more than there was before!!!
qvu2 years ago
why is the air pump is necessary?
FuzzeeDee qvu1 year ago
The air pump provides the source of CO2 for the algae. There are a couple of products from the pet store that could be helpful. You can get large vertical cylinders that already have valves sized for standard air line used in fish tanks which is what u want. Then u want to buy enough bio balls to fill each tube, the bio balls multiply surface area for algae to grow on and will significantly reduce uncontrolled clumping, greatly increase algae capacity and provide hundreds of times the surface area to facilitate the CO2 to O2 transfer, also makes cleaning out dead algae much easier. Simply swap out 'dirty' bio balls (ones clogged with dead algae) and replace with clean - don't replace more than 70% of bio balls at a time. By the way, just wash the dirty bio balls with mild soapy water, rinse well and reuse. Hope this helps. • • • Fuzzee Dee OUT • • • }~{ <> }~{ ^~^ :->
RilesT2 years ago
So are you just pumping surrounding air containing CO2 into the bottles, or do you have your hose attached something that creates large amounts of Co2? (ie a water heater or chimney)
mbcarroll2 years ago

Ok, the forum ate my first version of this post even after me seeing previews and seeing it posted after I hit the "Post Comment" button. I suspect my session timed out and the system is not smart enough to deal with me coming back in terms of an error or recovery. Fine, it happens - not all software can be great software. So I retype a second time and try switching to the "Rich Editor" (which is apparently quite poor) and everything I had typed in the plain editor was deleted and replaced with a really fancy display advertisement inside the editor window! ??? It's 2012, not 2002 folks...this is just poor. My first and last day of posting here all at once.... :(

Good luck to all. Seems like the contributors here are doing really interesting things and are very enthusiastic. Sorry to abbreviate so much on my third try (at least I explained above?), there was some commentary that I'm not rewriting again...here's the links though, maybe they'll be interesting or useful to someone:

http://solar-components.com/AQUA.HTM

http://www.aqua-medic.com/products/plankton-reactors-saltwater/

mbcarroll2 years ago

A few thoughts/links to add which may be helpful or interesting.

A German company (US branch) called Aqua-Medic makes a line of so-called plankton reactors which might be useful if anyone wants to get a little more sophisticated. They come with some fittings and a valve at the bottom (or looks like just a valve on the littlest one) that allow a way to inject air strategically and to make draining convenient.

If you're inclined to "go big" (and vertical) you might consider these algae-culture cylinders from Solar Components Corp. While not the cheapest net price/gallon, that's the best deal per square foot of floor space that I'm aware of.

There used to be a drip irrigation kit for sale that had a pump pre-wired for solar, but I can't find a link now....stupid internet is too big. ;)

Awesome instructable!

I have heard about how Sodium hydroxide, or Lye, absorbs Co2. How much would it take to make a scrubber capable of scrubbing a bedroom?
I'm sorry but I have no information on using lye as a carbon scrubber. By "scrubbing a bedroom" I presume you mean to remove all the ambient CO2. That would depend on size, air flow and so on. Unless you're dealing with a closed system such as a spacecraft I'd be inclined to think that it could be reduced but not eliminated. And CO2 in ambient air isn't generally considered medically significant as far as I know. A house size scrubber is probably doable, the goal in this case would be to leverage the existing forced air system rather than to eliminate CO2 from the household. That's probably not something that can be done with recycled soda bottles by anyone other than Ed Begly Jr.
And what's the carbon footprint of the Lye-making process?



Wikipedia link.
egbertfitzwilly (author)  mbcarroll2 years ago
Depends on how the electricity for the electrolysis is generated. Solar, wind or nuclear would be 0, coal fired plant would about 9lbs per kWH.

I doubt that sodium hydroxide or any other lightweight technology will scrub an unsealed room.
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