THE DEVELOPMENT OF INNOVATIVE ENGINEERING STRUCTURES FOR OFFSHORE MACROALGAE FARMING

The industrial-scale production of macroalgae (seaweeds, kelps) in oceanic waters is a branch of offshore aquaculture that has the potential to dwarf other forms in terms of both food production, environmental benefit, and energy production.  Ocean-based biomass production can be accomplished without displacing land-based food crops or impacting present uses.  The photosynthetic efficiency of aquatic biomass is 6 to 8% compared to terrestrial efficiency at around 2%. The US has a vast Exclusive Economic Zone (EEZ), and combined with the additional continental shelf areas over which is has rights, the US controls more ocean area than any other nation.  In spite of these holdings, the US currently produces only 1.6% of global macroalgae harvests.  One reason for this is that other than a narrow strip of ocean along the coast and within protected waters, most of this area is too deep and too exposed for the use of conventional macroalgae culture techniques.

With support of the NOAA SBIR program, the project team set out to develop engineered systems that will facilitate the farming of macroalgae in the open ocean.  This presentation will report the findings from our 6-month Phase 1 effort that included the design, model construction, and wave tank testing of a prototype culture array aimed at enabling dense cultures of kelp (Saccharina latissima) and other species positioned in waters of any depth using a single-point mooring.

In addition, a geospatial model of the oceans was developed that includes relevant biological and physical growth factors to determine location-based growth rates.  Combined with other economic factors related to harvest, transport, and processing, a model has been developed to identify optimal locations for industrial-scale macroalgae farming.  This model and our wave-tank findings will guide our further development of affordable and robust systems for the production of algal biomass in sufficient quantities to support biofuel production and carbon sequestration.