PNNL

Abstract

Trajectory and biomass growth models were coupled to support a novel macroalgae harvesting concept known as Nautical Off-shore Macroalgal Autonomous Device (NOMAD). The NOMAD consists of 5 km long carbon-fiber longlines that are seeded and free-float southward along the U.S. West Coast for about 3 months before harvesting off the California coast, taking advantage of favorable environmental conditions. Trajectories were determined with the GNOME model, using 11 years of current and wind forcing from available HYCOM and CFSR reanalysis datasets, determining probabilities by running nearly 40,000 Monte Carlo simulations varying the start time and location. An accompanying biomass growth model was developed to estimate the growth of macroalgae based on the trajectory tracks, using nutrient data from the MPAS-O-BGC model and temperature from the same CFSR and HYCOM reanalysis products used for trajectory predictions. The trajectory and biomass growth models were applied to answer planning questions pertinent to the techno-economic analysis such as identifying the preferred release location, approximate pathway, timing until harvest, and estimated growth. Model results should eventually be validated by a real-world deployment of an instrumented NOMAD system.