An Algae Bioreactor from Recycled Water Bottles

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Picture of An Algae Bioreactor from Recycled Water Bottles
In this instructable, we describe how to build a photo-bioreactor that uses algae to convert carbon dioxide and sunlight into energy. The energy that is produced is in the form of algae biomass. The photo-bioreactor is built from plastic recycled water bottles. By designing the apparatus to be compartmentalized, we are able to do many experiments in parallel.

Michael Fischer
mfischer @t

By using algae as a biofuel, we can increase the world's supply of oil while at the same time we decrease the amount of atmospheric carbon dioxide used during its production. The resulting product is a sustainable biofuel whose carbon footprint is neutral inasmuch as the CO2 produced on consumption is essentially balanced by the CO2 used in its production. In this instructable, we first make the carbon dioxide delivery system, then mount the water bottles on a rack, and then inoculate the bottles with algae. After letting the algae grow for a week, we extract the biomass.
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Step 1: Make Carbon Dioxide Delivery System

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To make the carbon dioxide delivery system, connect an eight port sprinkler system manifold to a one inch long PVC pipe. To get good seals, use Teflon tape to tape the threads before attaching the pieces together. Next, attach the one inch pipe to a T-connector. Block off one end of the T-connector and attach the other end to a foot long PVC pipe.

Step 2: Attach Tubing to Manifold

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For each manifold, cut eight-pieces of flexible tubing and connect each piece to a port of the manifold. The manifold that I am using has a dial on each port to control the rate of flow. Make sure all the ports that you use are open and allow approximately the same amount of carbon dioxide to flow through the port.

Step 3: Mount Carbon Dioxide System

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Mount the air system to a metal rack using zip ties. Attach the air system to a tank of carbon dioxide.

Step 4: Mount Water Bottles

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Hot glue the water bottles to the metal rack.

Step 5: Make Algae Media

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We next make the medium to grow the algae. Although there are many possible mediums, a standard garden store fertilizer contains all the nitrogen and nutrients that the algae need.
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C I A H8 months ago

does it have to be fed with the co2 or can you use a regular air pump to circulate air into the bottles? might just take longer to grow?

lxlbacon10 months ago
Now do you supply your own source of CO2? As in, a tank.
elevalther10 months ago
Hi Michael
I like your bioreactor, but do you know it is possible to get a cheap algea screew oilpress- eventually bluepeints,


".....hopefully, in the future..."

A good description for most alternative fuels. I've been hearing that for 35 years.
twighahn2 years ago
how is this used for fuel?
Milke19912 years ago
How much energy you will use for compressing air into bottles?
jbpitcher2 years ago
If I misses this comment from someone else I apologize.
I believe this is the fuel of the future.
- However, my question is: how much net energy is actually gained by the time you run a compresses/pump to circulate the water, press out the oil and other processes needed to gain a usable product.
- How extensive is the processing needed to turn the algae into a user-friendly product.
- How interchangeable is the end product with existing fuel consuming machines/engines.
ilpug3 years ago
awesome, although i noticed that you said that "By using algae as a biofuel, we can increase the world's supply of oil while at the same time we decrease the amount of atmospheric carbon dioxide used during its production"

i understand how this retains carbon dioxide, but how does it increase the world's supply of oil? it only reduces the speed at which we use said oil.

excuse me for being a grammar Nazi (although as you see mine is far from perfect).

I loved the instructable.
Nagarok ilpug3 years ago
This particular video refers to starch as "Oil"

Although it is a particular type of energy source, I personally believe it's incorrect to refer to them in the same manner. Starch is the solid condensed energy source that, with correct technology can be used to replace petroleum, but those systems are far more complex, and the output for mass for pure starch in terms of burning engines is lower.

Thats why fuels higher in ethanol, although much cleaner for the environment, also have a higher consumption per 100km driven. The initial cost of producing a fuel from plant sources is a very large sum of money compared to the petroleum based sources, that is why the world has not shifted across to alternative sources like biofuel. Eventually we will have to, else we will not be able to live anymore.
Live in the manner that we do at this time..
waldosan2 years ago
i think it's a smart idea to be doing this at least as a short term solution to our growing oil crisis. i'm thinking that if i build one of these i can burn the oil in an oil furnace to heat my house, in addition i could find/build a boiler and burner and possibly run a home made steam turbine off it. and grow my tomatoes in the rotting decay of the solids, that'll make them taste good!
WhiteTech2 years ago
I've read most of the comments. But pertaining to biodiesel, as in actually being used in cars, I've haven't found anywhere on how to do this. Just people saying "Oil to be used in making fuel"

I defiantly love the "Algae Pellets", but biodiesel would be much more useful in my position.
the oil is kind of like a replasement for used frier oil
I've seen this asked a few times and I couldn't find an answer yet - how much "fuel" (extracted and dried algae) does this experiment yield? I'm sure it can be estimated from the end photos, but I'm curious what Mr. Fischer gets after all this work? Is it enough to burn for 60 seconds? 5 minutes? Do tell! Thanks! :)

(My apologies if I missed an answer/reply to this question somewhere in the 200+ comments)

I did this and i got about 15 mL of bio oil
I tried this but is the algae bio-oil supposed to rise to the top? I noticed a small film of oil on the top of my bottles after 7 days. Also if it does rise to the top, any idea how to get it out? Thanks
Also, the french press does not obtain any bio oil on the filter...?
maliksudhir3 years ago
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 : ....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
pashanoid3 years ago
Thank you for this amaizing instructable! I now really want to build one of my own! However, up here in Moscow, Russia we don't get that much sunlight. Should I start with a scaled down model. I have one window in my apt facing west - gets the most sunlight... In any case -- great story, thank you!
jbuk13 years ago
visit the our online site for more information regarding photobioreactor
algaemaster3 years ago
do the tubes that the co2 passes through go in the plastic bottle through the top?
dawgz0314 years ago
wow...this is a really nice step to reduce global warming when connected to the co2 scrubber....
the co2 scrubber gets the co2 in the air...then it is feed to the algae......and more  i saw some article about specific algae that can be cultured so it can be used as a fuel or something when it is processed...

but there are still questions about the process on how to transform algae to a fuel.....and how to extract co2 of caustic soda....

can some on please help me???
is there some one who know more about caustic soda and algae???
Pe-ads dawgz0313 years ago
Isn't the algae a good enough scrubber? :D

Plants are carbon-neutral, as all the CO2 that gets released when you burn it, gets absorbed when a new plant grows.
fossil fuels are technically carbon-neutral as well. they were once plants that took CO2 from the atmosphere.

'carbon neutrality' doesn't apply to specific fuels, it applies to a process of removing the same amount of carbon from the atmosphere as you put in; for whatever good or damage that will do.

Perhaps it should read "biosphere neutral"? Adding fossil carbon to the biosphere changes the composition of the biosphere.
Thats the big problem.
that would be a more accurate term since the biosphere remains equipoise.

as for that being the big problem, it's just the popular opinion at this time. popular opinions aren't always right.

CO2 is the primary plant fertilizer. i wouldn't be keen on removing too much of it. i would rather be worried about increasing the O2 supply as that is becoming dangerously low.
By primary, do you mean limiting plant fertilizer? If so this is not true. Phosphorus and Nitrogen are limiting, and much less abundant. It is these nutrients that dictate plant growth, and of course carbon consumption. It should not matter how much carbon you pump at a photosynthetic organism. It will not take up any more than is dictated by these two nutrients. This is why forests would not be adequate carbon sinks.

I can see this becoming a problem as well. I would imagine that if done at an industrial level, companies only trying to make a buck will pump more and more fertilizers into their algae farms. These are the same chemicals that cause algae growths in streams and lakes when they run off from farms, lawns, etc.. Eutrophication is an environmental catastrophe which is destroying aquatic life and resources. The dead zone off the coast of New Orleans is a result of this process and others.

Judging on the fuel industry's track record, I am positive that it will end badly. It is a shame too. This seems like a great biofuel.
The motivation for a company not too pump too many fertilizers into there algal solution would simply be the cost f fertilizers, that would be one of an algae farms biggest costs, and with money on the table you can bet the company will use just the right amount...Just a thought, perhaps one of these such farms could sit on the Mississippi river and simply feed their algae on the water in it, we all know theres plenty of fertilizers within
You would think this is a major motivation, but industry, agriculture, and lawn care enthusiasts f**k this up all the time. This is why the Mississippi river is so rich in fertilizers. Every time anyone in the Midwest over fertilizes it ends up in the Gulf of Mexico. This is on top of all the other inefficiently used pollutants found in run off, and all the failing sewage treatment plants.

Lets not forget, it would be energy companies (BP, Exxon, Shell, etc.) doing the energy production. They seem to find a ways to screw up every last detail, and then fight tooth and nail to deny responsibility. Did it make sense for BP to construct a crappy well that failed, killed 10 people, lost millions of gallons of valuable crude oil, and lost them over 20 billion dollars? ...Somehow yes.

On the positive side, I think it would be a great Idea to use algae in this way. What about using algae farms as pretreatment for sewage? I wonder what other pollutants could be processed by algae into less harmful chemicals.
You have good point there, i have often thought, if only we could someone convince farmers that it would be cheaper to use less..... On the waste treatment idea, I don't think algae works very well with waste treatment, the newest system for that (atleast where i live, near the mississippi) seems to be simply open air tanks for a period to kill of bacteria then draining across a large field that treats the water over a period until it washes in wetlands....Usually bacteria are better suited for such waste treatment

Check out this site. The only problem with this is the algae use the CO2 produced by the bacteria, not by the later burning of the algae as fuel. Similar symbiotic relationships are found in eutrophication. Do the algae farms discussed in this instructable account for this? We are dealing with a more controlled environment, but how easily could the bacteria that eat dead algae contaminate the operation? If they did they would be the primary contributors of CO2 to the algae, and possibly decrease biomass yields. This might defeat the purpose.
Interesting thought, In the case of this instructional obviously no bacteria is present, though also in reality the farmand process depicted in this instructable is only useful as a concept, since, in all likely hood the process above requires more energy than it produces....But back to the bacteria i really don't know, that would certainly be something to consider
Different types of plants take up CO2 at different rates. So this "fertilizer" gives some plants a big advantage over their neighbours. Result, extinction of the neighbour! It is also well known that if you boost fertilizer to a plant, you have to boost water supply too in drought areas.
Thank you, you have highlighted another of the destructive effects that we have as we boost the CO2 levels in the atmosphere and in the sea and fresh water bodies.
The increase of CO2 in the atmosphere decreases the number of stoma on the plant, thus decreasing the amount of water used by the plant. More CO2 equals happy planet. There was a time where the percentage of CO2 in the atmosphere was much higher than present day - that was the time of 3 foot dragonflies and ferns that dwarfed trees of today.

yes. the percentage of oxygen was much higher as well.

there is a downward oxygen trend and if it goes below 15%, we could have a mass extinction event.
you haven't made much of a case. expanding on this logic; reducing CO2 would then give advantage to the plants that absorb CO2 more slowly thus driving the plants that absorb it faster to extinction.

fortunately, it doesn't work that way. there are many other environmental factors that determine the success or failure of a particular species. you even mentioned one of those factors... availability of water!

Arano dawgz0314 years ago
Na2CO3 + water +heat transforms to NaOH+co2 one of the easiest ways to transform your algae into somehting useful would be heating it up which would transform the algae into coal and burnable gases
rbarba Arano3 years ago
Here is a solution:
Dry up the algae then use biomass to make some pellets and finally use algae-pellets into a simple gasifier.
See for example this 'open-fire' gasifier: Luciastove at

It is possible to put aside most of the woodgas produced while the stove is burning only 5% of it.
Luciastove byproduct is biochar that is very good to enrich the soil.
And here is your transformation :D
yellowcatt3 years ago
As I see it there are three ways of using the algae for fuel:
1. Dry it and burn it.

2. Extract oil and burn that, you would still have biomass that could be either burnt or used as fertiliser. I suspect that to get a viable yield of oil will require particular varieties of algae and possibly careful balancing of the nutrients. To use the oil as a fuel it would need processing from a triglyceride to a methyl ester.
Craig Venter of Synthetic Genomics is working on bioengineered algae for this:

3. Use the algal biomass in an anaerobic digester to produce methane, you would still have biomass left which could be used as fertiliser or dried and burnt as fuel.

All are possible but economic and technological factors will decide which are most viable, the algae oil has the most potential but also requires the most development to become viable.
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