Development of scalable coastal and offshore kelp farming for marine biomass production

Abstract The US DOE/ARPA‐E MARINER program funded a 4‐year project to determine an optimal way to grow kelps in large, nearshore and offshore arrays for the eventual purpose of biofuel production with the goal of keeping the cost below $80 USD per dry metric ton of kelp. This project specifically looked at how Saccharina latissima can be grown in the Gulf of Alaska to reach that goal. There were three major aspects of the research: (1) optimize nursery production and seeding lines for outplanting; (2) design an economical, modular outplanting structure; and (3) develop methods to efficiently harvest the product. Farm designs were based on catenary structures and the use of spreader bars with variable spacing of grow‐lines and line types. The spacing of the grow‐lines makes a difference in the yield. Grow‐line spacing of ≥1.5 m showed about a 50$80 USD per dry metric ton of kelp