Microalgae (diatom) production — The aquaculture and biofuel nexus

As fishing has become more industrialized and wild fish stocks increasingly depleted, aquaculture production has grown rapidly to address the shortfalls in capture fisheries and limitations to long-term aquaculture success. One such shortfall is the need to produce a suitable, sustainable, substitute for the capture fishery derived fish meal and oil based fish feeds currently in use, while maintaining the human protein requirements and health benefits of Long Chain (LC) omega-3 oils in farmed fish products. Fish derive the LC omega-3 oils from the food they consume, which ultimately comes from lower trophic level primary producers like microalgae. Using Integrated Aquaculture System (IAS) principles and practices, microalgae (diatoms) can be raised and processed directly for their Algal/Single Cell Oils (SCO), protein, and nutrients. Besides the use as an aquaculture feedstock, microalgae have been investigated for biofuel production because of higher photosynthetic efficiency, higher biomass production, and faster growth compared to other terrestrial energy crops. SCO based carbon-neutral renewable liquid biofuel solutions are currently under investigation but suffer from high production costs. Liquid biofuels have been considered to displace non-renewable, petroleum-derived transport fuels of limited availability which contribute to climate change via greenhouse gas (GHG) emissions. The current high cost constraint of SCO production could be alleviated through explored water-energy-food nexus synergies between the aquaculture and biofuels sector with a concentration on innovations in microalgae/SCO production, harvesting, and processing technologies. Interdisciplinary collaborations between engineers, biologists and chemists are essential for their successful development.