A new study has been published in Biotechnology for Biofuels by several university researchers from Europe and China that investigates the effect of initial-biomass-specific (IBS) light availability on batch microalgal triacylglycerides (TAGs) for Nannochloropsis sp. cultivated in vertical and horizontal outdoor tubular reactors at different initial biomass concentrations for the TAG accumulation phase, during two distinct seasons (high and low light conditions).

In the paper, titled “Microalgal triacylglycerides production in outdoor batch-operated tubular PBRs,” the researchers state that algae products have not been economical yet mainly because of low productivity, which is strictly dependent on IBS light availability—defined as the ratio of light impinging on reactor ground area divided by initial biomass concentration per ground area.

The results showed that increasing IBS-light availability led to both a higher IBS-TAG production rate and TAG content at the end of the batch, whereas biomass yield on light decreased. As a result, an optimum IBS-light availability was determined for the TAG productivity obtained at the end of the batch and several guidelines could be established.

In their conclusions, the authors write that “from this study, the great importance of IBS-light availability on TAG production can be deduced. Although maintaining high light availabilities in the reactor is key to reach high TAG contents at the end of the batch, considerable losses in TAG productivity were observed for the two reactors regardless of light condition, when not operated at optimal initial biomass concentrations (15 to 40 percent for vertical reactors and 30 to 60 percent for horizontal reactors).”

For the complete study, and all of the technical data, results, methodology and conclusions, click here.