Farming seaweed at exposed ocean sites requires a careful balance of costs and risks. In the present case study, a multi-tile kelp cultivation array was designed for an exposed site in the Gulf of Maine. This system employs novel components to minimize animal entanglement concerns (composite lines with large bending radius) and maximize grow line area per site area (modular tiles with low-scope mooring lines and helical anchors). Thus, simulations were used to understand the behavior of the prototype farm prior to deployment and quantify loads on the anchors and structural components. To mitigate the risk of structural failure without incurring excessive capital and operational costs, the system was evaluated using a simulation technique that has been demonstrated to predict mooring loads within 15% of those measured at sea for an exposed kelp farm.
Fifty-year extreme current speeds, significant wave heights and associated peak periods were quantified by incident direction and by month-of-the-year. Simultaneously considering the biomass growth by month of the year and the monthly current and wave extreme values reduced capacity requirements by 48% compared to the conservative assumption of maximum biomass with the maximum significant wave height and current speed. Anchors and structural components were designed to maintaining safety factors in consistent with marine industry standards for both the intact case and damaged conditions, mitigating the risk of catastrophic, cascading anchor-line failure in the array.