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Algae Bioreactors: Advantages and Disadvantages

algae bioreactors

Cultivation in algae bioreactors, or “PBR’s” are tanks or closed systems in which algae are grown. Algal culture which is grown can have a single algae strain or contain a number of strains. It depends on the type of end product desired.

Controlled amounts of water, nutrients and carbon dioxide are provided in the culture medium. Oxygen liberated as the result of photosynthesis is removed from the tanks. Sunlight is provided either directly with transparent tank walls or light tubes are placed which channel sunlight.

Algae bioreactors are also optimized to maximize algae cultivation.

In closed systems, algae growth conditions can be regulated much easily and precisely by engineers. Closed systems include photo bioreactors for producing species of photosynthetic algae. Traditional bioreactors made up of closed tanks are used for species (e.g. cyanobacteria) which do not require sunlight.

Why Use an Algae Bioreactor?

algae bio reactor

When it comes to growing algae you have two choices in life…open ponds or algae bioreactors.

Depending on your application, volume of algae needed, and climate will determine which method will work the best for you.

An algae bioreactor (PBR) can be described as an enclosed, lighted, algal culture vessel designed for controlled production of algae. Photo bioreactors, have several major advantages over open ponds, they can:

  1. Prevent or minimize contamination
  2. Offer better control over existing conditions (pH, light, carbon dioxide, temperature).
  3. Prevent water evaporation,
  4. Lower carbon dioxide losses due to out gassing,
  5. Permit higher cell concentrations.
  6. Allow you to grow algae in any climate

However with the advantages come disadvantages as well. Namely,

  • Cost
  • Size and scope
  • Technical expertise

Let’s take a look at each of these in more detail before we begin…

Algae Bioreactors Advantages and Disadvantages

Advantages:

Test algae Bioreactor
  • Prevent contamination: One of the biggest problems with opens ponds (in my view anyway) is they are susceptible to contamination from invading and/or native species. In a PBR all inputs are completely controlled by you, not chance or nature. This is a HUGE advantage.
  • Allow you to grow algae in any climate: This is one of the main reasons for a PBR. It allows you to grow algae easily and cheaply in almost any climate. Open ponds are an unacceptable alternative in many colder climates.
  • Bioreactors offer better control over existing conditions: Since you’re controlling all the inputs, you can also (better) control the existing conditions of your algal experiments. Meaning climate, light, temperature, Ph balance, nutrients, etc. Many times this isn’t possible in an open pond situation. For example it is hard to control the amount of sunlight in a given location. However with a PBR it is as simple as resetting a timer.
  • Prevent water evaporation: Water evaporation in an open pond can be difficult situation to control. Where water is scarce this makes open ponds an unacceptable choice.
  • Lower carbon dioxide losses: If you have a unlimited source of waste carbon dioxide this isn’t a problem, however most home users aren’t in a situation of living next to a power plant…they have to buy it in canisters. In order to minimize costs, this becomes a consideration.
  • Permit higher cell concentrations: Because you’re controlling the parameters of the PBR, you can also control the density of your cell colonies. While possible in an open pond, it is much easier in a PBR.

Disadvantages:

algae bioreactor
  • Cost: Until now, algae bioreactors were considered the realm of corporations due to the high cost of fabrication. Indeed the high cost of acrylic tubes, especially as the price of oil increases, is enough to give one pause. The key to controlling the cost of PBR’s is in “Yankee ingenuity.”
  • Sure, it’s always possible to complicate things and charge extra. No problem there. However to use existing inexpensive, local resources to create a PBR the knowledge has been non-existent. Until now. That is one of the main reasons for producing this book.
  • Size and scope: For the most part, algae bioreactors have been confined to laboratories with relatively few being fabricated for large scale production. That is now changing. The size and scope of your algae bioreactor is also dependent on your application. Many (most) uses don’t require a large scale PBR…health food supplements, for example. You can easily make all the Spirulina and/or chlorella your family would need with a small PBR. Algae bio fuels for example, go to the opposite end of the spectrum. Here you need to produce a large amount of algae to be successful.

If you're interested in learning how to build an inexpensive small to medium scale bioreactors for your home or lab Building Algae PhotoBioreactors at Home is the best book available on the subject.

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The Algae Revolution Has Begun

algae biofuels
algae bioreactor
I learned more from your eBook than spending $6,000...

Dear David,

I have learned more from your e-book than spending $6,000 going to the Algae World 2009 Conference in Rotterdam. Do you have the same manual for Jatropha? Many thanks,

Thanks in advance

Jim Riordan
Perpetual Prosperty Pumps, Africa
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Click Here to Leave a Comment Below 4 comments
mundekesye - April 19, 2012

so does it mean that with PBR’s a production plant can be growing vertically instead of horizontally.

Reply
    admin - June 27, 2012

    Absolutely. In fact, the research I’ve seen concludes that vertically is the preferred way to go.

    Reply
Steve Teter - July 26, 2012

Dear Mr. Sieg:
I find Alge procution to hold the most promise to our current problems facing mankind and its future. In reading the advantages and disadvataged to photo bioreactors versue open pond prodution of alge. I have been thinking of this for years since reading about alge biofuels. It is said that they can be grown in saline waters and utilize land that cannot be used for agicultural production. I always thought that the deserts of western Utah would be a great place for a large scale open pond procution facility. the saline water from the Great Salt Lake basin could be pumped out into the deasert area into covered ponds to help control evaporation, and plus there is virtualy nobody living out there. There is open rangland used for cattle prodution, but is such poor rangeland there there is but one cow per 5 square mile and the forage byproduct produced could replace that. Water is a concern out in the Utah desert but with covered ponds to control evaporation it is viable. I don’t know what concentrations of salts PH. factors are acceptable for alge growth and withevaporation those levels will increase. That being said I belieave that alge and kelp prodution are the answers to our fuels and food, forage problems that will be facing mankind in the near future. Its has been said that alge prodution will not use one acre of cropland to produce all of tha energy nessasary to power the future, and using the oceans to grow brown kelp will use no water, fertilizer to produce ethanol and are one of the fastest growing biomasses in the world. Sincerly

Steve Spudfed Teter

P.S. I’m from Idaho

Reply
    admin - July 26, 2012

    Hi Steve,

    All the points you made above are true. Algae can be grown in highly saline waters. In fact, some species thrive in it. Right now in the Salton Sea, faced with the many of the same conditions you’re talking about, the algae industry is taking off. You may want to check the newspapers in the area to see how, and what they are doing. The algae strain used will depend on location, but yes, you have it right. In a situation where evaporation is a concern, a covered/closed pond is the technique to use. Some algae strains are high adapted to high pH and saline, others aren’t. What you can do is study the local native algae of the area. I’m not saying a local algae will yield oil (probably won’t) but I am saying that it will give you a clue as to which direction to go in to find an oil bearing strain not effected by the climatic conditions presented. I hope this helps, and good luck to you.

    Reply

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