Which is better for the industrial production of algae? Flat Panel Reactors or Tubular Glass Photobioreactors?
Do you want to grow high-quality algae on an industrial scale? Closed photobioreactors (PBR) are best suited for this purpose. They protect your algae from harmful environmental influences.
If planning on cultivating algae in a closed PBR, the use of flat panel reactors initially appears as an interesting approach. These flat panel systems are usually made of polyvinyl chloride (PVC). In theory, this method offers high light absorption due to the way that it is constructed and results in rapid algae growth. In practice however, numerous influencing factors reduce this advantage. Therefore, tubular glass PBRs are widely used in the industrial production of high-quality algae.
Below you will find a comparison of flat panel reactors and tubular glass PBRs. The comparison focuses on important factors influencing the results of industrial algae cultivation:
Flat panel reactors made of PVC need to be replaced every 1-3 years at the latest, mainly because of UV degradation of PVC. Glass tubes on the contrary can be used for up to 50 years at the same level of productivity.
End of Life Costs
These costs occur when the flat panel modules need to be disposed once they reach their end of life. Firstly, PVC can’t be burned that easily, because toxic gases arise. Secondly, it is not possible to recycle PVC as it absorbs organic material over its operating life. Therefore, it is necessary to dispose such modules correctly, whereas glass is endlessly recyclable without a loss in quality.
Total Cost of Ownership
High replacement costs are the main cause of why flat panel reactors show a significantly higher total cost of ownership in comparison to glass PBRs. Initially, flat panel reactors made of PVC cost almost the same as comparable tubular glass PBRs of the same volume. However, due to the modules having to be replaced after three years at the latest, the replacement costs increase the TCO significantly in comparison to a glass system that can be productive for 50 years without replacement.
Biofilm Build Up
PVC has a surface roughness that is nearly 50 times higher than glass. Therefore, the algae builds up on the surface of a flat panel module much quicker than on the inside of a glass tube. This limits the productivity of a flat panel reactor.
Cost of Cleaning
The main difference regarding operating costs lies within the cleaning process: Tubular glass systems need to be cleaned far less often. Most of the time the system can be cleaned chemical free. This takes place during operation. Whereas for the cleaning process of flat panel modules, the algae production needs to be interrupted to clean with chemical detergents or high pressure water jets.
Predictable and plannable Production
Due to the reliable operation of tubular glass PBRs, the algae production can be planned very well, whereas the production in flat panel reactors tends to often be interrupted unexpectedly for numerous reasons.
Tubular glass PBRs as well as flat panel reactors are both particularly productive algae cultivation systems at initial operation. The productivity of flat panel reactors however suffers from multiple production interruptions due to biofilm build up. After 1-2 years in running operation, flat panel reactors lose their productivity due to UV degradation and biofilm that can no longer be removed. Tubular glass PBRs on the contrary, run for many years at the same level of high productivity.
This article is an extract from our e-book “Algae cultivation in flat panel reactors compared to tubular glass PBRs“. If you would like to inform yourself in detail about the advantages and disadvantages of flat panel reactors in algae cultivation, you can download the e-book for free.