Simple Algae Home CO2 Scrubber - Part 1

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.

Step 1 Bill of Materials

Okay here's what we'll need:

Tools:

Drill or drill press with 3/16" bit
Razor knife or scissors
Hot glue gun - Optional
Funnel - Optional for filling bottles

Materials and where I got them. I have no relationship with any of these stores or products. They are inexpensive and should be commonly available:

1 X 8' 1/4" aquarium airline tubing - PetSmart Top Fin brand or ACE Hardware flexible plastic tubing
1 X 3' 1/8" inch rigid plastic air hose (3/16 outer diameter) - PetSmart Top Fin brand
1 package 6 air stones - PetSmart Top Fin brand (also available individually)
1 x 2L Clear Plastic soft drink or water bottle with screw on top - Recycled
1 x 2L de-chlorinated water for breeder reactor

On the next page we'll learn more about dechlorination

Comments

[RilesT]

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)

[mbcarroll]

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/

[mbcarroll]

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!

[nicolasw]

Hi, i'm intressesed in reproducing your experiment in my room to remove CO2 and clean the air of harmful toxins and stuff like that. However i'm worried that the algae will produce other gases like methane. Will the algae produce methane thanks.

[egbertfitzwilly]

This is discussed in some detail in other posts but this will do not want you want.

But to answer your question:

Algae, like all living things, have a life cycle. Although it is not what one might think. As algae reproduce they split into up to eight daughter cells, all internal. When the daughter cells get big enough the parent literally explodes and the remants, of course, will sink. This process is called flocculation.

In most circumstances these will decay and produce biogas, of which methane is a significant component.

[qvu]

How did you calculate the carbon consumption of the CO2 algae scrubber? was their a formula involved? or a machine?

[egbertfitzwilly]

The consumption calculation is based on the NASA study attached. The pump is required to insure that sufficient CO2 is available in the bottle. In an open container gas uptake from the atmosphere only penetrates about 6 cm from the surface, bubbling the gas through the tank ensure that the entire colony has sufficient dissovled gasses for operation.

[qvu]

Is it possible for me to reproduce you're model on a larger scale?

[egbertfitzwilly]

This isn't the best design for that. The NREL report has a raceway pond design that is much better suited, the Alabama study also has a very scalable model including production revenue models.

[qvu]

Thanks, I was thinking about replicating on a larger scale too, how long did it take your algae to fully culture, cause I've been waiting on mines for a couple of days now and it's making very little activity. Should I turn on the air pump to accelerate it. Also when should I clean it, cause I've seen the consequences of an over abundance of algae, such as large clumps of algae. So would those Large clumps of algae potentially block the air pump and cut off the nutrients to the entire colony? If so, would u recommend a stronger air pump?

[qvu]

Is the air pump still required to be used once you've grown the algae in the bottle successfully?

[qvu]

why is the air pump is necessary?

[maliksudhir]

Hi ,
Can any one help me out in some calculation work its really very urgent , please help me out ..... i need to consume 1932.3kg/hr of CO2 with the help of Algae in a pond (water) for example Raceway pond , so i need to know the specific area to construct that pond and its sizing and dimension (length,etc) and the quantity of water needed and amount of algae used so that it easily consumes the mentioned amount of CO2 rate per hour..... please help me out soon you can also drop your suggestion and questions if any my email id is : [e-mail] ....i will be waiting for your reply soon and i'll be highly thankful to you, if someone can help please do tell me its very urgent....

Thank you

[egbertfitzwilly]

You need to read the NREL study and the Alabama study in great detail. The design also depends on what you are scrubbing. If you are breeding algae for industrial or agricultural purposes the Alabama study has a complete model you can plug into a spreadsheet.

If you are attempting to scrub emissions from coal, internal combustion or other active generation source you'll need a bubbler tank design that captures 100% of the gas and bubbles it through enough to water to fully absorb the emissions.

Any significant design will requires substantial real estate and a non trival industrialized infrastructure.

[maliksudhir]

Thank you for your suggestion , but i need to know that as i have the turbine system (plant) which releases Co2 at the rate of 1932.3kg/hr and i need to consume that Co2 with the help of Algae in pond just like as the Raceway ponds do ...i have all the specific industrialized land area to construct the pond and to perform this task i just need to have the specific size of the pond system which can consume 1932.3kg/hr of Co2 so that i can perform it on the large scale project with minimum cost involved for example " http://www.ems.psu.edu/~elsworth/courses/egee580/Utilization_final_report.pdf " ...... you can take a look at that pdf file on page number 9 figure 2.1.4 ,i just need to have the minimum area to make that pond including the calculation of all the dimension and all including minimum cost ....but the main focus here is the calculation of the pond area , i just need to have the total area of pond (sizing and dimension) (length,width,depth and all)which can perform this task of consuming Co2 at rate of 1932.3kg/hr with the help of Algae.........i am in great confusion with my calculations and i need help can you please help me out in performing the calculation work and finding out the specific area needed......i am really very thank full to you...........Have a Good Day

[egbertfitzwilly]

Is your goal to actually remove the CO2 from the emissions or to scrub an equivalent amount of CO2 from the surrounding environment to offset the exhaust gases? I don't believe it is possible to actually scrub the exhaust but offsetting sequestration could be done with ponds.

Once you've captured you're 2000 kg/hr have you considered what you are going to do with algae, once its floculated? The problem of algae breeding isn't the breeding, its what to do with several tons of dead algae? The ponds are the start of your problem, not the goal...

Gathering and organizing the kind of information you are seeking is a non-trivial challenge. Such an undertaking of itself would be a time consuming (and costly) matter requiring the attentions of knowledgeable professional in the field. I would recommend someone but I don't know anybody in the field that does this sort of thing.

[thecoonskin]

Do I really need the aquarium bubbler stone? Couldn't I just let it absorb the Co2 in the air?

[egbertfitzwilly]

There are certainly alternatives but there are some things to consider.

Gas uptake in air generally penetrates to a depth of about 6 cm which limits the depth of the tank and corresponding requires shallow pools with a broad surface area. This approach has its own limitations.

The NREL proposed a waterwheel type of assembly that rotated and circulated the water is travelled in long racetrack shaped pools. The UofA study expanded on that by using an aeration ramp and pouring water over it to get increased gas uptake with a significantly smaller surface area.

This design uses the air pressure both to aerate the tank as well as to rotate the algae population within it, in a production environment it could be used to very efficiently aerate a deep narrow in ground tank to obtain the maximum production per acre.

The pump in this design far exceeds the fundamental nature of the design, you could obtain improved efficiency with a larger tank which might help alleviate your concerns.

The water in the tank should rotate from top to bottom at least once every 6 seconds. A simple windmill lift that pumped water from the bottom and dumped it out, preferably in air, over the surface so that it falls through the air a little bit would be ideal.

[ortsa]

So whats the point of doing this? Making all my mothers house plants die or what?

[egbertfitzwilly]

Its an experiment model that can be used to explore the fundamental processes, plus its kind of fun and it makes an interesting conversation piece in some circles.

[satya1]

Hi I have made such an algae reactor, but it does not grow the algae, freshwater algae, like, a nearby pond that I put water bottles, how many hours of light to be illuminated, the bubble was how long it must have to go?

[egbertfitzwilly]

Algae are pretty strong. The optimum cycle is 18/6 although I'm confident that a shorter cycle of air flow should produce consistent growth.

Did you fill the bottles from the pond? Municipal water supplies are often treated so that tap water must be de-chlorinated otherwise it will kill the algae.

If you filled the bottles from the pond, put in a bit of fertilizer and ran the pump 24/7 I would expect you have a very healthy visible growth within a few days.

[pazvlad]

I like this idea but how much CO2 is released by running an air pump 24 hours a day work out to be? this will reduce the overall net CO2 conversion.

[egbertfitzwilly]

Yes, that's why I use a 2L bottle. The pump I recommend is rated at 1.8W which is roughly 15 kWH annually. This is scrubbed in 6 weeks and the first liter becomes a carbon consumer after that. So in theory is ~17 kwH and 34 or so kWH every six weeks after that. The pump is one that I could find which was inexpensive, low energy consumption and readily available. It will easily support multiple reactors. This solution has some drawbacks, for instance there is a minor cost (at the individual level) for the electricity. A 0 net CO2 footprint makes it CO2 free but not free free...This is why large scale CO2 scrubbing isn't being proposed without an offsetting revenue stream. Unfortunately there is nothing that promises to subsidize large scale installations. However a grass roots effort which distributes the cost among willing participates is an eminently scalable solution without consuming significant resources for the industrialization process and cost recovery infrastructure. Also depending on how the algae are disposed of during periodic cleaning ( the most likely scenario being dumping it on the compost heap or garden ) some CO2 may be re-released although most gets returned to organic material as nutriets which is processed by plants that, in turn, consume CO2 and so on and so forth. Setting this aside there is no other positive scrubbing technology which approaches the cost-effectiveness of algae which is why its being applied in industrial emissions scrubbing.

[bobb3666]

couldn't we just all plant trees?

[egbertfitzwilly]

Got my vote. Trees, and the related paper products, are an excellent mechanism for sequestering carbon. While some gasses are released during decomposition the majority of the carbon remains locked up in the plant matter. When the paper cups go into a landfill that carbon is sequestered for a thousand years with absolutely no potential for long term environment or health issues.

[satya1]

Hi I have made such an algae reactor, but it does not grow the algae, freshwater algae, like, a nearby pond that I put water bottles, how many hours of light to be illuminated, the bubble was how long it must have to go?

[theinzen]

Thank you for posting this. I am curious, how did you come up with the 24 lbs of carbon dioxide a year? That consumption is about 29 grams/day. If one air stone in a bottle runs about 5l of air through the material, you would only pull out about 12 grams/day if it removed all of the CO2. Also, do you have any idea how effiecient a single pass is? If the air in my house is 600 ppm, what concentration could you expect to have coming out of the scrubber?

[theinzen]

I actually have a CO2 sensor mounted in my house. I should tell you the reason for my interest. I cultivate mushrooms as a hobby and some mushrooms like air under 600 ppm for fruiting. Unfortunately, according to literature, a well ventilated house runs 600 - 1000 ppm and this is consistent with the readings I usually get. I obviously can't purge the mushroom chamber down to less than 600 ppm CO2 if the inside air is higher than that. I probably need to eat up 25g/day CO2 in whatever device I choose. An alkaline scrubber is an option too, but I like your idea better as long as the maintenance is low. I built a one gallon version of your unit and I currently have 2.25 l/min air running through the unit. The output is running through the CO2 sensor so if your interested I will tell you how it does. I am waiting for the algae to get going now. Doesn't seem like you would want to run much more air than this through the container so if it pulled all the CO2 out of this flow it would be about 6 grams/day. I appreciate the document you attached. I also like the idea of having a longer tube. Thanks again!

[arutkow]

theinzen, If you grew your mushrooms in a sealed room, and also ran one of these carbon scrubbers in the selaed room, wouldn't you be able to vent the oxygen-rich air produced by the algae to outside of the mushroom chamber, and eventually reduce the CO2 levels to below 600? Of course, once the seal was broken to the mushroom room, the CO2 levels would even out with the rest of the house. Egbertfitzwilly, does this sould do-able? Perhaps if instead of unscrewing the popcap 1/4 of a turn, perhaps 2 holes could be drilled into the cap, one for the bubbler air to go in and the other for a hose to direct the venting air to a different location? Thanks for a great instrucable! -Abram

[theinzen]

I moved away from this option. I could never get significant quantities of CO2 removal. The problem you have is you can put a whole lot of air flow through a pop bottle. If you do put a lot through, you have a very short residence time and large bubbles which translates into poor Co2 absorption into the water. You could make taller column and/or more columns but both increase the energy required to pressurize the air. A 50" high container would be nice, but you need an air pump that can put out 50" of water pressure. I found out I could simply pull in purge air from the outside cheaper than I could accomplish an internal CO2 removal. I think algea based CO2 removal is probably a good idea, but you probably have to harvest the oil and other byproducts to make it economical.

[arutkow]

I just thought of something....would mushrooms and algae both grow in the same environment? I always figured mushrooms preferred shade. -Abram

[egbertfitzwilly]

Yes the lid can be dual ported and the exhaust gas ported to any number of uses. I'm planning on using that exact design to scrub the input stream for my Al-Air battery. If there is in actual fact a mushroom chamber it might be beneficial to pump the air into it. Keep in mind that it is also O2 enriched and I have no idea how the mushrooms might feel about that.

I'm also getting very good results in a 5 gallon pail with a filter pump that provides aeration. I'm using a Bio-Wheel style pump without inserting the actual filter. This provides aeration by rotation and may provide a higher volume ambient scrubbing.

http://www.petco.com/product/2402/Marineland-Penguin-BIO-Wheel-Power-Filters.aspx?&cm_ven=PriceGrabber&cm_cat=Fish&cm_pla=Marineland&cm_ite=989746

[egbertfitzwilly]

That's based on the potential of the algae to absorb about 1 mL of CO2 a minute ( the paper title Gas Exchange of Algae is attached ) per liter of algae medium. Getting the CO2 to it is left as an exercise for the reader... I haven't done a yield analysis based on weight, processing algae to get dry weight is exceedingly tedious however significant volumes are produced. Relatively speaking of course. I drain these regularly so I can work with the algae in my MFCs. I'd be very pleased to know of a more in depth analysis of actual production results. I found a nice battery powered pump and have ordered a couple, a revised version using a solar recharger will be posted once I get them. That will reduce the carbon footprint and increase the overall efficiency. Gas uptake in a bubble chamber is a function of a variety of factors including the specific gas, tower height, size of the bubbles, temperature, pressure and saturation of the fluid. I would expect this apparatus to reduce the CO2 gas content by at least a factor between two and three. A 1 meter tower should reduce the CO2 by a factor of 10. How did you get 600 ppm in your house?

[dpsilver]

I wouldn't agree with how the algae r disposed, some experiments with large scale testing uses the algae to make ethanol to help reduce the costs of running it.

[The Locksmith]

After browsing 85 pages of instructables in the technology section, I finally find a project that interests me! I am going to get started on this, and I will post photos when I am done. Thanks for the idea!

[lemonie]

Why did you count the pages?

L

[The Locksmith]

They're numbered

[lemonie]

Oh yes, you didn't count them.
Sorry, my mind must have been elsewhere.

L

[The Locksmith]

=P