Introduction: An Algae Bioreactor From Recycled Water Bottles

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.

Step 1: Make Carbon Dioxide Delivery System

Picture of Make Carbon Dioxide Delivery System

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

Picture of Attach Tubing to Manifold

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

Picture of Mount Carbon Dioxide System

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

Picture of Mount Water Bottles

Hot glue the water bottles to the metal rack.

Step 5: Make Algae Media

Picture of Make Algae Media

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.

Step 6: Media Inoculation

Picture of Media Inoculation

A good source of algae is pond algae, if available. If not, there are a large number of online vendors that sell batches of algae. To inoculate the culture, measure out a fixed amount of algae and add it to the growth medium.

Step 7: Growth and Harvesting

Picture of Growth and Harvesting

After several days of sunlight and CO2 exposure, the algae are much denser. A French press is then used to extract the algae from the solution. The biomass of the dried algae can then be used as a fuel. As a by-product of this process, a large amount of atmospheric CO2 is sequestered.

By: Michael Fischer, Stanford University, mfischer @t


SHOE0007 (author)2017-03-29

In terms of carbon dioxide being released what if we

1. Burned it with a high concentration to replace coal or partly.

2. Reduce rotting of algae that releases methane into the air.

3. Made algae to absorb CO2 from the air.

crazymuggerz0 (author)2016-09-07

if you shown us how to make it how do we link this to make power?

awi putra (author)2015-11-30

I cant understand how algae can used for this kind of stuff, is the algae making such as biogas or we must took the algae out and produce it to be a niofuel ??

JacksonPollock (author)2015-08-25

moonsoup (author)2015-03-03

After reading as many of these comments as I could stand it's obvious to me that we will all have to evolve to breathe CO2 and H2O.

Or drown and suffocate....together.

klehman1 (author)2015-02-18

So what do I do with the algae to so that it doesn't get burned or decay letting CO2back In to the air

livinlifegreen (author)klehman12015-02-27

To keep the C from cycling back into the atmosphere sounds like it might be difficult.

If you use the algae as a feed then the C is used to prododuce new animal biomass (whether it's a fish or a human, ect.) although once that organism dies then bacteria will get to work and the C will once again be in the atmosphere.

There is a man who spoke about sequestering all the excess CO2 in our atmosphere in the soil by increasing root production, combined with no till. the idea is that if plants take CO2 from the atmosphere and use it to produce deeper roots and we do not till it, then most of the C will continue to stay below ground and the level of soil will increase. ... So perhaps burying the algae could cause it to become sequestered. Probably not a reasonable thing to do, but it will be just like what happened millions of years ago that provides is with fossil fuel oil today.

Calladus (author)2009-02-03

A tree could sequester biomass if you turned it into furniture or a house. Burning it is carbon neutral, as long as you're farming trees. Burning the algae would be carbon neutral. Turning it into plastic or something might sequester the captured carbon - if you were careful about the energy you used in the process.

dedsetmad (author)Calladus2009-02-05

Burning anything is not carbon NEUTRAL....Burning releases the carbon into our atmosphere...back to chem. class.......

Calladus (author)dedsetmad2009-02-05

tsk tsk - perhaps you should re-read what I've said?

Jux (author)Calladus2009-03-13

More food for thought than anything else, but has anybody ever considered the idea that just possibly burning oil is also carbon neutral? Hear me out before you rant and rave, this is just me thinking 'out loud'. For example: burning algae is only carbon neutral as long as you look at the complete cycle from beginning to end; the length of time it takes to remove CO2 from the air, process it, and return it to the air. Is it possible we are only looking at a portion of the cycle of oil? After all a lot of it once walked around this planet on 2 or more legs before being contained in the ground. If we were able to see the entire cycle what would it look like? Don't get me wrong I fully support alternative fuels, I have just never heard anybody talk about a possible cycle of oil or coal. -Jux

ash.springer.9 (author)Jux2015-01-29

in terms of the earth, burning oil is carbon neutral in terms of the human race and surviving the atmosphere it is not, as the earth sequestered the carbon and produced oil as a sync if all the carbon is released then the plants will be fine especially c4c6 plants but humans will perish, it could also be neutralised by mass farming trees sequestering carbon and then biocrude put into the ground but this is never going to happen simply, your right not the whole carbon cycle in terms of the earth is taken into account its all rated against human tolerance of co2 in the atmosphere this is the hitch i believe youve noticed.

AngelaG2 (author)Jux2014-11-09

just a little reminder jux...natural gas and pertro derive fro plankton and coal from plant matter ?

Calladus (author)Jux2009-03-13

It's true if you define a long enough cycle it might encompass the cycling of biological material (of which we are a part) back into sequestered carbon. But the rapid conversion of sequestered carbon into free carbon might also cause the extinction of humanity due to a too rapid change in climate and pollution. The length of the cycle doesn't matter if one small part of the cycle is responsible for the death of us all. The questions are, will we survive the rapid change of carbon status? Should we be concerned about climate changing chemicals in our biosphere? How can we figure out if this is a problem? What can we do about this while we figure things out? It would suck for humanity to go extinct in the next few hundred years due to our own incompetence in the way we manage our biosphere. The logical thing to do would be to minimize our impact until we have a better understanding about what is going on.

ash.springer.9 (author)dedsetmad2015-01-29

lol dedsetmad, your understanding of the carbon cycle is fairly basic in the nicest way possible its best not to assume what your told is true without first researching the subject as calladus is very right and your looking very ignorant. burning fossil fuels is carbon negative we cant replace the oil or more we wont, we can sequester said carbon tho in trees and then sync it into the ground. a tree grown sequesters atmospheric carbon, if n when you cut it down and burn it it becomes carbon neutral because the carbon the tree sequestered as carbon negative is released as carbon positive and the two 'charges' neutralise one another = carbon nuetral.

back to chem class ;)

servant74 (author)dedsetmad2009-09-11

Look at your time frame. ... You are right, in the short term. ... But 'farming' (algae, trees, etc) is 'harvesting' the carbon from mainly the atmosphere. Farming does a 'temporary sequestration' if you 'burn' the tree or algae, up to the point it is re-gasified by the burning process. The only reason that burning coal or oil is not considered 'carbon neutral' is because the time frame we are viewing is to short. ... Peat that is burned some places as fuel is carbon neutral over a 10 to 200 year period. Most farmed pine trees are typically on a 10 year or more cycle, oak is longer, bamboo is shorter. Again, it just depends on the time frame. Our bio-system is not a nice set of linear equations. We can typically find the reactions for simple systems, just not for the more ones with more complicated connections.

larry03052 (author)dedsetmad2009-02-06

Wrong. If the carbon produced came from the air in the first place, then the burning is carbon-neutral by definition. Burning wood is carbon neutral. Burning coal is not, since the carbon in the coal was removed from the atmospheric cycle millions of years ago. Perhaps you could use a refresher course in chemistry yourself.

Calladus (author)dedsetmad2009-02-06

Carbon Dioxide + water and light in photosynthesis creates carbohydrate – the major component of Cellulose (plant matter). When Cellulose is burned it creates Carbon Dioxide and water vapor and more heat. The problem with burning fossil fuel is that a LOT of oil and coal has sequestered a LOT of carbon over millions of years. And in less than 200 years we've drastically depleted these reserves and released all of that carbon. The logical thing to do would require humanity being carbon negative for the next fifty to hundred years. But large groups of humans are rarely logical. Being carbon neutral is something we're just now starting to understand and agree with as a species.

k2daz3 (author)dedsetmad2009-02-05

As Calladus said, as long as you are burning plants and algae rather than the oil found in the earth's crust, you are actually carbon neutral. Any CO2 or Methane released by the burning of such materials is only equivalent to the amount that would have been free in the atmosphere had the plant not temporarily sequestered it. Burning oil extracted from the earth is not carbon-neutral because it is releasing carbon into the environment that otherwise would have remained trapped deep underground. So yes, Back to Chem. Class for someone... Environmental Science helps too

static (author)Calladus2009-02-06

However this is "farming" algae. Burning any product produced from the algae is carbon neutral as is burning tree's. The same is true for burning biomass. There may be varying degrees of efficiency, I don't know, but it has to be better than releasing prehistoric carbon into the atmosphere.

ash.springer.9 (author)2015-01-29

i was thinking of brewing alcohol and using the waste co2 once it had been decanted using the fact that its heavyier than air, it gets to fairly high concentrations tho ive never measured it when u crack a brew barrel if you breath the air you can feel the sting of the carbon dioxide im guessing it turns to mild carbonic acid in your lungs making you cough or else the co2 concentration on an exhale of our respiration would burn us so clearly alot more co2 than our exhale.

once you had tapped the gas and stored it either under pressure or at atmospheric in another empty (but not empty as it has co2 in it) barrel. have an 'air' pump inside said barrel and you would have a co2 pump? this would be brilliant as its amalgamating waste streams from one bioreactor to another where it becomes fuel. squeezing that carbohydrate for every last drop of use instead of venting to atmosphere and then using commercial co2 for an algae reactor which is also going to atmosphere. another way you could produce co2 as apposed to a pressurised commercial bought can, is with carbonic salts like they do, again in brewing with beer to carbonate it. this would probably produce a waste stream of carbon dioxide but could be reused id imagine not that im overly against venting to atomsphere im more against buying the co2 in the first place.

pukashells808 (author)2015-01-22

can this algae bioreactor produce mass amounts of c02 and if it can is there a way to minimize this system in order to use the co2 for aquarium plants

Unknown419 (author)2014-10-24

What type of air system did he use to feed the Carbon Dioxide into the system? Is there a place to purchase this?

C I A H (author)2014-02-22

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?

lxlbacon (author)2013-12-22

Now do you supply your own source of CO2? As in, a tank.

elevalther (author)2013-12-09

Hi Michael
I like your bioreactor, but do you know it is possible to get a cheap algea screew oilpress- eventually bluepeints,



ArtisanEclectic (author)2012-12-06

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

A good description for most alternative fuels. I've been hearing that for 35 years.

twighahn (author)2012-10-15

how is this used for fuel?

Milke1991 (author)2012-10-01

How much energy you will use for compressing air into bottles?

jbpitcher (author)2012-09-28

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.

ilpug (author)2011-07-30

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 (author)ilpug2011-09-13

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.

sXeffects (author)Nagarok2012-06-14

Live in the manner that we do at this time..

waldosan (author)2012-06-03

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!

WhiteTech (author)2012-01-28

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.

Sun Gear (author)WhiteTech2012-04-16

the oil is kind of like a replasement for used frier oil

mharrington5 (author)2011-07-30

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

ihatescience (author)2011-11-28

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...?

maliksudhir (author)2011-08-24

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

pashanoid (author)2011-06-19

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!

jbuk1 (author)2011-06-18

visit the our online site for more information regarding photobioreactor

algaemaster (author)2011-02-03

do the tubes that the co2 passes through go in the plastic bottle through the top?

dawgz031 (author)2010-01-15

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 (author)dawgz0312010-12-02

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.

tomas.savage (author)Pe-ads2010-12-02

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.

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Bio: Michael Fischer
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