Robotic algae harvester: A novel method for efficient algae collection

Abstract

Algae are potential renewable energy source that provides numerous types of biofuels. Traditional methods of algae harvesting involve high electrical energy in the range of 200–5000 watt-hour for collecting per kilogram of algae. Moreover the added chemicals during the harvesting process degrade the algae quality leading to inferior biomass feedstock. Based on a comparative analysis of the various algae harvesting methods, this paper introduce a novel robotic algae harvesting system. The focus was on algae harvesting with less energy consumption and without the use of chemical flocculants. Design dimensions and size of the robotic algae harvesting system were determined based on the size of the raceway pond where algae was harvested without any operational trouble. Two algae collection units were designed using plankton nets of 5 µm which facilitate in the collection of the algae. With torque analysis on the system design, the electrical actuators and power source for the harvester was resolved. A wireless switch control system was designed for controlling the harvester’s locomotion while collecting the algae from the raceway pond. The developed system was tested in a raceway pond where it successfully collected a total of 565.67 g algae in 200 test runs in 1 h and 6 min. The estimated total electrical energy consumed by the robotic algae harvesting system to collect per kilogram of algae was 110.5 watt-hour.