Optimization of Microalgal Biomass Cultivation and Harvesting Considering Culture Crash Events

Producing microalgal biomass has become one of the advancing means of realizing cleaner production and energy generation. This production process is a viable candidate for numerous reasons: its relatively low land footprint, its aversion of the food vs. fuel dilemma exhibited by other biofuels, and its capability for carbon capture and use and waste recycling. Despite these advantages, cultivating microalgae is still susceptible to scenarios that inhibit its continued production. In brief, a culture crash is an example of this challenge where various factors contribute to the decline or interruption in growth. These crashes then affect other processes downstream, impairing the whole process. This study attempts to investigate the direct effects of culture crash in microalgal biomass production by developing a mixed integer non-linear programming (MINLP) model considering cultivation and harvesting. This model, which is not computationally intensive, was used in two case studies where culture crashes were enabled through a mean time to failure (MTTF); the cases differ by the length of their MTTF. Results show that shorter MTTFs require twice as much algae starter and result in about a 1.5% decrease in estimated profit from about 591,000 USD to about 583,000 USD. This indicates the relevance of finding solutions for culture crashes in production; stakeholders may then use this study to value reliability in these production processes.