What to look for when planning a photobioreactor
If you are planning a photobioreactor (PBR) for algae cultivation you will realize very quickly that there are a variety of factors that influence what cultivation method and photobioreactor design best suits your particular situation. In a free fact sheet we have collected the seven most important decision parameters for you. You should consider these when choosing between different photobioreactor systems.
In this blog post we present three of the seven parameters:
- Space requirement and water consumption
Two limiting factors for photobioreactor design and scaling:
- What production space is available for the reactor? Can it be easily expanded?
- How expensive is the water needed for cultivation?
First indications: a closed system can accommodate five to ten times the amount of photoactive cultivation solution in the same space as an open pond. At the same time, a closed PBR with the same amount of water can produce a much larger number of algae than an open pond. Depending on humidity and temperature, between 5 and 20 percent of open water evaporates every day, which then has to be replaced.
Key question: What influence do space requirements and water consumption have on your equipment planning and total costs?
- PBR productivity
The most significant measure of PBR productivity is areal productivity. How much biomass can you produce on a certain piece of land in a certain time? PBR types differ quite clearly in some cases due to their designs. Only the 2-3 cm of algae breeding solution closest to the light is photoactive in an open pond. Beyond this layer, the algae’s own shading is already too much for further photosynthesis. The more light that reaches as large a photoactive volume as possible, the more productive a PBR is. In an open pond, this photoactive volume corresponds to the upper 2-3 cm of the space the pond takes up. A tube system, however, can be erected 6 m high with a tube diameter of for example 6 cm, illuminated from all sides by artificial lighting. The areal productivity of such a system is up to ten times higher than that of open ponds.
Key question: How high must my areal productivity be to make your business situation pay off?
- Predictability of production
Industrial algae production usually means being part of a longer supply chain. This makes it very important to have cultivation processes that are as stable as possible. Only then can production be planned reliably and delivered to customers in accordance with off-take agreements. One problem with plastic PBRs is that they tend to build up biofilm relatively quickly. Cleaning biofilm from plastic systems requires interrupting production every time, as chemicals are used. 2-3 days of production are lost per cleaning process. Glass systems, on the other hand, can be mechanically cleaned with pipe pigs during production. However, things can become problematic if the algae solution is contaminated with foreign organisms, which can kill an algae culture (culture crash). A culture crash can cause not only the loss of your entire algae cultivation, but also cause 2-3 weeks production downtime because of decontamination and inoculation of a new culture. Open pond systems are particularly susceptible to culture crashes since the algae solution is not separated from environmental influences.
Key question: How important is the stability of your production processes to your business model?
Download our free fact sheet “The seven most important decision parameters for choosing the right photobioreactor” now.
There you will also find out more about the following important questions:
– What role does the type of algae you want to cultivate play in selecting the right PBR?
– Which type of PBR is appropriate for certain geographical locations?
– What influence does the quality of biomass you want to achieve in your cultivation have on the choice of the suitable PBR?
– How does the selected PBR type influence the total cost of ownership of a PBR? Additionally how do these costs influence the production costs of your algae?