The Algae Experiment: How to Build Your Own Algae Photo-bioreactor.




In this instructable we will go over how to construct an at-home version of a photo-bioreactor which will use solar energy and artificial lighting with carbon dioxide to produce algae biomass.

The aim of this project is to create an model which harbors an ecosystem fit to help us escape a fossil fuel economy. We are in an era that is experiencing a shift from humanity trying to dominate nature, to then trying to preserve parts of nature and now trying to reach a reconciliation with nature. This is the algae experiment; an idea that is trying to move away from a linear wasteful and polluting way of using resources to a closed loop system where all resources are kept in a closed loop cycle.

Check it out working.

Follow the possibilities of harvesting algae for fuel & see the difficulties met along this journey on-line at


a published paper on the subject can be found on


For more info or to get in touch you can reach me at

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Step 1: Shape, Size & Materiality

The over all shape of the photo bioreactor is inspired from a previous project I had been working on where it follows a mean summer solar path of the UK. It is meant to be both an educational model but also embody certain architectural elements within allowing it to possibly be viewed as an informational pavilion.

Step 2: The Ribs

I considered using two materials for the support system.

I tried clear acrylic so as not detract from the function, which would be the algae tubes containing the algae. However. having to deal with all the transparencies of the materials made the model seem very confusing.

I needed each rib to consist of two pieces of wood in order to provide a stable ‘leg’ for each segment whilst I would be putting the model together but also to be able to withstand any rocking from pressure the model would experience during the cultivation hours. I ordered 50 M4 grub screws with a cup point and 150 M4 hexagon nuts and got started on the ribs. (M4 denotes the diameter of the screw; 4mm) I spaced the ribs apart 20mm which allowed them to be able to free stand. Together all 5 sets made a very sturdy model base.

Step 3: The Tubes

I wanted to use a closed loop system where the algae would travel constantly and safely without getting contaminated, so using clear acrylic tubes was the best option.

I initially wanted to use 15mm outer diameter tubes with an inner diameter of 12mm in order to carry the water required to grow the algae, as well as to match the pump power (4000 Liters per hour) that I had obtained for a previous model. However I quickly realized that at every return point of each tube there was no silicone or plastic based hose that was flexible enough to bend around to each connection point.

This wasn’t all disappointing as it meant that I could downsize to 12mm outer diameter tubes with an inner diameter of 8mm and save on cost at the same time. Unfortunately even though I moved down to that size, finding a hose which would fit on the outside of the 12mm seemed impossible.

That is when I decided to try to enter the 8mm inner area of the tube; something considered very unconventional and ‘inconvenient’ but to me this was the only option as far as flexibility was concerned with the materials available to me. I found a 8mm outer diameter silicone tube and it fit perfectly inside.

Step 4: How It Came Together

The trouble now was to sort out the frequency and amount of tubes per rib. I needed enough to cover as much of the surface as possible in order for the algae to capture as much light as possible. I therefore ordered 20 x 1m length 12mm outer diameter tubes. This allowed me enough spacing to double up in the future on the inside if I could raise more money to have a second set under the first set of ribs.

Although at first one pair of tubes seemed easy to connect to each other with the 8mm silicone hose, repeating the process 40 times with such a small radius and a tendency to buckle in and fold on itself seemed impractical. I therefore had to come up with a different system of transporting the algae from one tube to the next. This meant either re-designing the ribs to a much larger scale which would set each tube further apart or changing the tube to an even smaller size which would allow me to purchase an even thinner hose with more flexibility to achieve that goal.

I decided not to go with either, instead I changed the pattern of transport; rather than consecutively going from tube to tube, I would skip 3 tubes on one end and 2 on the other, 3 on one, 2 on the other and so on and so forth. This allowed me to stick with the same design & tubes which were already put together and get a much larger radius which would ensure that the hoses would not pop out of place because of the pressure or their internal positioning in the acrylic tubes

Step 5: The Plinth/base

With the ‘above ground’ part of the model completed, it was now time for the plinth to be constructed which would house all the mechanisms that would operate the model ‘below ground’. The plinth required to place the model on a height which would be comfortable to be viewed by an audience of both children & the elderly but at the same time not be overstated and detract from the model itself.

I decided to make it 1m tall and allow 15cm for each side of the 1m tubes to have space for the turnaround of the hoses. The final dimensions of the plinth were 1m tall, 1,3m long by 0.3m wide.

As this was going to be both an exhibition piece and a University project I felt that there was a strong educational aspect to it. I wanted to somehow be able to tell the story of the algae with this model. I decided to make viewing holes on the rear side which would show the process much like the doughnut company Krispy Kreme has certain stores where the customers can see the production line of how the doughnuts are made from the dough to the glazing.

On these holes I would label what each component would do. Bio-reactor, CO2 pump, air intake, light source. Once deciding on the location of these objects, I decided that rather than having separate holes with separate names, it would be better to have one panel which would be seen as one object containing all the information one needs to know which would be far less distracting.

This turned out to be a really good choice after all and the laser cutting machine did an excellent job. Etching turned out to be much harder than I thought as every letter had to be converted to an object which meant that there was a much higher chance for an error to occur. Each letter had to be checked and cleared of any unwanted lines as well as check for disconnections in the comprising lines.

Step 6: Colour

After that the plinth was ready for painting, a clean white look turned out to be the right choice and a color scheme of white, natural ply & clear proved successful. In hindsight I should have used far less paint quantity on the water tank door as the 3mm ply could not handle the paint and warped. It is purely an aesthetic problem, one that can be addressed after the exhibition is over.

Step 7: Sealing the Bio-reactor

With the plinth drying it was now time to seal the tubes and the hoses shut to make a closed loop bio-reactor. I used the super-instant glue rather than silicone because of its ‘instant factor’ and the fact that the hose & tube were such a tight fit that silicone would only create clumps inside the tube and probably cause more problems than it was worth.

When trying to fit each hose in the tubes it was extremely hard to get each one in at first. To solve the problem I countersunk all the tubes in order to get a ‘start’ in each hose so that it could slide in with ease. This was an excellent solution as later I poured glue on the countersunk tube with the hose in place which created a lake which would seal shut. Result: not a single connection out of the 40 connections leaked.

Because the tube was a very small space with a limited air supply, the instant glue would not dry instantly, this created a small puddle inside each connection. I therefore had to try various positions every 5~7 minutes to ensure that each connection would seal on all 360o.

Step 8: Hose Fitting

A minor adjustment had to be made to the pumping mechanism. Due to the fact that the 4000 Liters per hour was significantly more powerful than the 15 Liter water tank I was intending to use I had to make an outlet where the pumps power would effectively be cut in half in order to take the stress off all the plumbing connections so they would not suddenly blow apart from the pressure.

The adjustable handle also meant that I could regulate the speed at which the algae would travel round the model and effectively either accelerate or decelerate the growth when needed.

Whilst I would be transporting the model, I would like to have the ability to separate the bio-reactor from the plynth. I used some heavy duty clip-on clip-off fittings which allowed me to completely disconnect the bio-reactor without compromising any connection points.

Step 9: Test Runs

After letting the glue settle for 40 hours, the first test run with still water was extremely successful. The air bubbles traveled at a steady pace throughout the model and all the connections held up perfectly. This run lasted for 4 hours. I then proceeded to add algae incrementally over the next week.

Step 10: Growing the Initial Algae Culture Pt I

During the building period, I had started to grow algae using the simple method of a water bottle, algae food & the sun. This proved successful in the UK but even more successful in Greece where the sun lasted for longer during the day. I started with a culture sent to me by the Algae Depot of 50ml and after a few days I reached 3 x 100ml travel bottles.

I then proceeded to continue to grow that culture until I eventually reached the required 5.5 Liters after approximately 2 weeks. The algae was growing exponentially quicker due to the limited bottle room I would provide along with excellent sun exposure and feeding regime.

Step 11: Growing the Initial Algae Culture Pt II

Step 12: Test Runs

I let the algae run in the bio-reactor for 10 days and achieved excellent results.
Perhaps it was the location of the model posistioned against a window which received very good sunlight both artificial and genuine but it had grown at a steady pace becoming greener every day.

Step 13: Outcome

Being an ongoing project I do not have the algae biomass output of this experiment yet. 

I will keep you posted through my tumblr blog

where any publications results and other events that will be organised shall be posted.

Thank you for looking through this instructable and please contact me if you need any further info.




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    58 Discussions


    3 years ago

    Hey Charles! Could i know a little bit more about the "Carbon Pumping System", it seems to me the most expensive and difficult part to implement. If i could get any tips or information of how you did it, i would appreciate very much! Thanks!


    3 years ago

    I am doing this for a science experiment myself for my school science fair. What type of algae did you use to fill the tubes/tank with?


    4 years ago

    what kind of pump was used in this system? I have been trying to think about it for a while now and not sure what could pump water, air and the small solid algae. I attempted to send an email to the a few days ago and have not heard anything back. I wanted to attempt to build something like this but scaled up a bit but have been unable to think of a pump or search for one online that I think would accomplish the task of pumping air water and small solids.


    5 years ago on Introduction

    Nice report I hope to make something like this one day. I plan on trying to mix this with another instructable ( to make an indoor oxygen scrubber, and food source. Who knows maybe it can even be used in fuel useage, but I will have to research more.

    I was thinking of getting a UV tube light, a 3"X(uv tube)" and a 5"X(uv tube)" lengths of plastic (UV resistant) or glass pipes. With a mirror to reflect any excess light. The bubblier for CO2 at the bottom and O2 extracter at the top (I will need to look into this). Any reason this shouldn't work? Why are you using a series of small pipes instead of one large tank? Should I base a design off of a series of smaller pipes instead of one sheathed tank?


    6 years ago on Step 13

    Have you been able to make any algae biofuel?


    7 years ago on Step 13

    This is all very new to me and quite exciting! My only concern is that the power to extract the usable oil seems to run the gamut in power consumption making it a moot point. Unless it is possible that the biofuel is so efficient that it could produce enough power for the extraction process and then some I don't see how this is applicable as a long term solution. Does anyone know the relationship between the amount of energy needed for extraction and the amount of energy produced per unit of Algae based biofuel?


    7 years ago on Step 13

    Pretty slick, did you consider just using a continuous length of tubing for the top part? Instead of the sold-flexible connections just "laced" the whole thing with one continuous piece?


    Reply 7 years ago on Introduction

    Higgs is right, through processing the biomass you can get a new form of fuel essentially.

    If you would like to read more I have published a paper on the whole project on issuu.


    Reply 7 years ago on Introduction

    Beautiful looking report!

    I've been looking at using the extracted algae oil (and any other cheap and/or waste veg or animal oil/fat triglyceride) as 'green diesel', different from 'biodiesel'.

    Biodiesel is typically fatty acid methyl ester (FAME), made by reacting veg oil with lye (hydroxide) and methanol, yielding stuff that can be used in place of diesel fuel. Advantage: easy to convert in a backyard barrel, good lubricating properties; Disadvantage: can 'gum up' due to other double bonds elsewhere in the fatty chain, like varnish, thus destroying most fuel injectors, pumps, etc. Also, a more powerful solvent than regular diesel, so need viton fuel lines, gaskets, etc., and better fuel filters because the FAME tends to dissolve all the crud in the tanker, storage tank, transfer lines, your fuel tank, sending all the gunk straight to your filter, or worse, injectors. Nasty.

    'Green diesel' is diesel made from renewable sources like veg oil. Can be made by hydrotreating veg oil using a Ni-Mo catalyst at maybe 300'C and 50 Atm pressure, not unlike making margarine, but more so. Adv: very high 'cetane' rating (like 'octane' for petrol / gasoline) at maybe 95 cf. 'regular' diesel at 51 cetane rating. Can therefore be used to blend into low grade diesel. Hydrotreating with hydrogen gas can fully saturate double bonds in the fatty chain that would otherwise lead to gumming up.

    Oh, yeah, great that you're using the natural floatation of the algae to enrich for species / strains that yield lots of oil and oxygen! Ideally the whole reactor tube system would use both the thermosiphon effect (heating up on exposure to sunlight) and the decrease in cell density due to oil and gas accumulation to help circulate the algae through the pipes.

    Keep us all posted on how it's going, m0uch!

    PS, would it ice up in winter over your way?


    Reply 7 years ago on Introduction

    Hi wblack3,

    Lots of good additional information for an already great Instructable - thanks!

    I was wondering about people running used fryer oil from restaurants in their diesel powered cars; as I understand it, all they generally do is filter it to remove food particles. From what you say, though, it seems that if they used fresh veggy oil they would run into problems. Is the fryer oil actually improved because it's used? I'm guessing something like the high heat and the H2O boiling off from the food while it's cooking is doing something to modify the oil's composition? If so, that's pretty cool that you get two uses out of a renewable resource, with the first use improving it for the second use! (Unlike diesel, which no one wants their fries boiled in :-)


    Reply 7 years ago on Introduction

    Hey, Jexter,

    I had to look it up. It's funny, what they told me at uni years ago was that fats/oils get hydrogenated or at least lose their polyunsaturated 'goodness' after being heated for a while... i.e., used for cooking.

    So my lecturer in biochem reckoned that polyunsat oils were really no better than sat fats like palm oil, coconut oil, etc.

    However, this was at odds with what I also knew from chem eng in that hydrogenation, to be efficient, requires higher temps (300'C), pressures (2.5 atm), H2 gas, a catalyst like Nickel or Copper complexes on a silica or alumina (or both) support (really just wee ceramic beads usually).


    The Iodine value is an indication of how unsaturated the oil is, and usually equated with how unstable it is, but others have indicated this is not always the case. An unstable oil is not what you want to put through your high pressure common rail fuel system and injectors, esp. if running a sweeeeet sweet VW golf series5 2.0 L TDI... as I am ;-)

    The common rail system gets up to over 1000 atm, a recipe for all sorts of chemical craziness to bust out.

    Does look like the longer an oil is used for cooking, the more 'burnt' and partially oxidised it normally becomes, but not nec. a great reduction in the double-bonds that are the 'unsaturated' or high Iodine number factors that I thought would lead to chemical unstability, gelling, gumming of the injectors, burning / coking of the injectors and cylinders, etc.

    Personally, before I stick it into my sweet ride, you test it on yours and let me know how you go (and IF you go) ;-)

    Otherwise, I've been toying with the idea of using hydrogenation reactors and Ni-Mo catalysts to clean up algae oil, waste veg oil, grease trap gunk, and turn it into chemically stable fully saturated and low S, O, P, N oil more like petroleum derived diesel, or 'green diesel' rather than 'biodiesel' fatty acid methyl esters (FAME).


    ALogan97Higgs Boson

    Reply 7 years ago on Introduction

    I was actually planning to do just that for my Google Science Fair entry. Do you mind if I use your bioreactor in it? I'll credit you for the design.

    sffitzgeHiggs Boson

    Reply 7 years ago on Introduction

    True but I have a feeling this educational model is to illustrate how we can convert algae to biofuel because of the high percent of oils in the algae. Although, the harvesting techniques available make this process not economical. Hopefully someone will figure that part out soon.

    Cool model, and nice instructable! could you share a little more on why you made this bioreactor?


    Reply 7 years ago on Introduction

    Hi sffitzge, thank you for your comment. Yes the harvesting techniques are still being worked out, there is some great work done by a company called origin oil where they use a process called ultrasonification to separate the lipids for oil extraction. I made this model as part of my Architecture MA, it's a prequel to my Graduate Diploma project which you can find a summarised version of here:

    Overall I wanted create a piece which would be able to show people that anyone could start growing algae for the purpose of bio-fuels at home. This is not to say that it's either easy nor 100% feasible however it did provide food for thought for the people who attended the exhibition which I hosted in the UK.

    I know the extraction part is the 'hardest' part although growing the algae in large, effective quantities in itself is the first step..


    7 years ago on Introduction


    Could the algae and their byproduct not be used as a free fertilizer? I assume that the algae would be a great form of biomass and the natural gas byproduct would be full of nitrogen?

    Instead of fueling a car your fueling your home garden.

    Please let me know if i'm out to lunch or bang on?

    If i'm right I guess this is food for thought?

    3 replies

    Reply 7 years ago on Introduction

    Hi Derekvpierce,

    Yes the algae can be used for diverse reasons, although once used for its oil extracting purposes it can also be used as something else, usually livestock food because it is rich in nutrients. However, as I am not a scientist I cannot confirm about your nitrogen query. I will look into it and reply back.


    Reply 7 years ago on Introduction

    Algae cannot 'fix ' nitrogen from the atmosphere (Google 'fix nitrogen') ,so the only (soluble) nitrogen you get out is what you put in from the fertilizer used to run it