An Algae Bioreactor From Recycled Water Bottles





Introduction: An Algae Bioreactor From Recycled Water Bottles

About: Michael Fischer
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

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

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

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

Hot glue the water bottles to the metal rack.

Step 5: 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

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

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

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    how did you intake the carbon dioxide from the environment in this project ?


    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.

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

    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 ??

    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.

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

    1 reply

    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.

    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.

    12 replies

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

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


    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

    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.

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

    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.

    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 ;)

    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.

    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.

    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.


    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

    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.