A techno-economic analysis of industrial production of marine microalgae as a source of EPA and DHA-rich raw material for aquafeed: Research challenges and possibilities

Abstract

The aquaculture industry needs a stable supply of feed resource materials in sufficient quantities and quality for future growth, in particular the fatty acids eicosapentaenoic acid (dha) and docosahexanoic acid (DHA) which so far have been ensured by inclusion of fish oil. About 70% of the available fish oil is being used in aquafeeds, but the global supply of fish oil is limited and emerging omega-3 markets are competing with the aquaculture industry for this valuable resource. New sources of dha and DHA must be fully developed to cover the global demand, and marine microalgae are regarded as a promising alternative as the primary producer of all the EPA and DHA in marine food webs. Industrial cultivation of phototrophic microalgae is conducted in open pond systems or closed photobioreactor systems, designed to maximize the utilization of light energy and to achieve efficient uptake of nutrients and CO2. The economics of microalgae production heavily depend on the photosynthetic productivity, and there are ongoing efforts to increase the microalgae productivity following different strategies. The first is to exploit the cultivation conditions to direct the metabolism towards lipid production. The second is to improve biomass productivity or lipid yield by mutagenesis and selective breeding, and the third strategy is to improve strains by genetic modifications to optimize light absorption and increase the biosynthesis of EPA and DHA.The inclusion of whole microalgae cells in aquafeeds will require sufficient processing to ensure maximum nutritional uptake, involving dewatering and cell disruption in order to maximize the bioavailability of nutrients. The roadmap of microalgae to become a sustainable aquafeed resource must include interdisciplinary research and development efforts along the whole value chain to achieve biomass production in an industrial scale. A techno-economic analysis of microalgae production was conducted based on biological and technical parameters from the literature under various scenarios, showing that biological productivity, geographical locations and production technology are important factors to lower production cost. The production cost of EPA and DHA equivalents revealed the lowest cost for flat panel photobioreactors in locations with clear sky conditions. Sensitivity analysis showed that optimizing photosynthetic efficiency and doubling of the EPA and DHA yield could reduce the cost to 11.9 USD per kg of total EPA and DHA equivalents. Our findings suggest that focused research efforts can contribute to achieve economically sustainable production of microalgae rich in EPA and DHA for use in aquafeed in the near future.