Managing nutrients and system operations for biofuel production from freshwater macroalgae

Filamentous freshwater macroalgae have significant potential as a renewable source of bioenergy. However, the ultimate success of freshwater macroalgae as a biofuel feedstock will depend upon our ability to produce biomass at commercial-scale in a cost-effective and sustainable manner. Aquatic ecology can play an important role to achieve the scale-up of algal crop production by informing the rates of nutrients supplied to the cultivation systems, and by helping to create adaptive production systems that are resilient to environmental change. A review and analysis of data from the published literature reveals that the large-scale cultivation of freshwater macroalgae is feasible using currently available technologies such as the Algal Turf Scrubber® system (ATS™). In addition, graphical analyses of published data obtained from ATS systems of varying sizes in operation worldwide reveal that both macroalgal biomass productivity and nutrient removal rates are hyperbolically related to the areal loading rates of both total nitrogen and total phosphorus. The effectiveness and need for CO2 supplementation of macroalgal production systems like the ATS has not yet been conclusively demonstrated, however.