subject: Photoautotrophic Cultivation- Open ponds Vs Photobioreactors [print this page]
Algae-cultivation on a whole faces several challenges. There are two methods of growing algae - one is the photoautotrophic cultivation and the other is the heterotrophic cultivation. Photoautotrophic cultivation as the name suggests is cultivating algae in the presence of light the light can be either freely available sunlight or artificially provided light. Heterotrophic cultivation essentially means the algae is cultivated in the dark by providing it with some carbon sources such as sugar for its growth.
Photoautotrophic cultivation can be carried out in open-ponds as well as PBR's . There are many advantages of cultivating photoautotrophic algae in open-ponds- the first being the cost, it is about 7 10 times cheaper than growing algae in a PBR. Not only that the evaporative cooling maintains the temperature as well. However, its extremely difficult to maintain monocultures by using open-ponds. Moreover, the control over temperature and sunlight is also not possible.
Photoautotrophic cultivation in a PBR might sound very exciting as there is much less water loss when compared to open ponds, ability to maintain the cultures for a longer period. However, if costs are considered, its too much .Cleaning the PBR will also a major issue, the interiors of the PBR must be frequently cleaned due to biofilm formation. All the more, there are several scaling up challenges as well.
As a result, it remains to be seen which system will be preferred at scale over long periods of operation. Sometimes it will be neither open-ponds or PBR's through the photoautotrophic way, the heterotrophic route might prove successful.
