Deborah Sills, Assistant Professor of Civil & Environmental Engineering
We present the results from sustained tonne-quantity production of two novel strains of marine microalgae, the diatom Staurosira and the chlorophyte Desmodesmus, cultivated in a hybrid system of 25-m(3) photobioreactors and 400-m(2) open ponds at a large-scale demonstration facility, and then apply those results to evaluate the performance of a 100-ha Base Case commercial facility assuming it were built today. Nitrogen fertilization of 2-d batch cultures in open ponds led to the greatest yields – from both species – of similar to 75 MT ha(-1) yr(-1) biomass, and similar to 30 MT ha(-1) yr(-1) lipid, which are unprecedented in large scale open pond systems. The process described here uses only seawater, discharges no nitrogen or phosphorus in any form, and consumes CO2 at 78% efficiency. We estimate the capital cost of a 111-ha Base Case facility at $67 million in Hawaii, where actual production was performed, and $59 million on the Gulf Coast of Texas. We find that large-diameter, large-volume PBRs are an economical means to maintain a continuous supply of consistent inoculum for very short-period batch cultures in open ponds, and thus avoid biological system crashes that otherwise arise in longer-term pond cultures. We recommend certain improvements in cultivation methods that could realistically lead to yields of 100 MT ha(-1) yr(-1) biomass and >50,000 L ha(-1) yr(-1) algal oil. Comprehensive techno-economics and life cycle assessment of 20 end-to-end production lineups, based on the cultivation results in this paper, are presented in a companion paper by Beal et al. . (C) 2015 Elsevier B.V. All rights reserved.
Huntley, Mark E.; Johnson, Zackary I.; Brown, Susan L.; Sills, Deborah; Gerber, Leda; Archibald, Ian; Machesky, Stephan C.; Granados, Joe; Beal, Colin; and Greene, Charles H. “Demonstrated Large-Scale Production of Marine Microalgae for Fuels and Feed.” Algal Research 10, (2015) : 249-265.