PNNL

Abstract

The operation of microalgal cultivation systems, such as culture dilution associated with harvest, affects biomass productivity. However, the constantly changing incident light and ambient temperature in outdoor environments makes it difficult to determine the dilution rate that results in optimal biomass growth. To address this problem, we present a pond operation optimization tool that predicts biomass growth based on future weather conditions to identify the optimal dilution rate that maximizes biomass productivity. The concept was tested by comparing the biomass productivities of three dilution cases: standard batch cultivation, fixed-dilution (harvest 60% of the culture every three days), and weather forecast-informed dilution. In the weather forecast-informed case, the culture was diluted daily, and the dilution ratio was determined by the operation optimization tool according to the future 24-hour weather condition. The results showed that the weather forecast informed dilution increased the biomass productivity by 47% over the standard batch cultivation and 20% over the fixed-dilution case. These results demonstrated that the pond operation optimization tool could be helpful for pond operators to make decisions that maximize biomass growth in the field where weather conditions are uncontrollable.