The United Nations Intergovernmental Panel on Climate Change (IPCC) advises that by mid-century approximately 10 Gt CO2eq must be removed annually to prevent global surface temperatures warming by 1.5oC by 2100. Among the suite of carbon removal strategies is the farming of macroalgae and sinking of the harvested crop in deep water sites.
A robust bio-techno-economic model (BTEM) developed by Coleman et al. (2022) finds that a 1,000-acre sugar kelp (S. latissimi) farm in the Gulf of Maine could achieve a levelized cost of carbon of $1,257 CO2eq-1 when fully optimized. This represents a 14-fold decrease when compared with baseline assumptions.
This BTEM includes a structural analysis of a 100-acre kelp farm. The farm is composed of flexible members – ropes, chain, and kelp – which renders static and quasi-static analysis methods unsuitable. Therefore, a time-domain Hydro-Structural Finite Element Analysis (HS-DFEA) of the farm was developed to compute minimum capacities of structural members. The HS-DFEA informed selection of farm components such as ropes and anchors, which were used to estimate farm costs and the emissions associated with manufacturing, installation, and maintenance.
Three aspect ratios were considered for the prospective farm. Each was analyzed in 50-year environmental conditions, in accordance with existing aquaculture standards. Table 1 shows that the lowest cost per biomass yield occurs at the largest aspect ratio, illustrated in Figure 1