The Costs and Feasibility of Floating Offshore Wind Energy in the O'ahu Region

Abstract

This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. U.S. Department of Energy (DOE) reports produced after 1991 and a growing number of pre-1991 documents are available free via www.OSTI.gov.

Wind Energy Costs in Puerto Rico Through 2035

“…The assumed 1,300-m maximum water depth limit is consistent with recent NREL floating offshore wind cost and resource studies (Beiter et al 2020;Musial et al 2021a;Shields et al 2021b) but does not represent a hard technology limit. Industry practitioners agree that floating wind systems in deeper waters beyond 1300-m are technically feasible provided the seabed slopes are not steep, and that the primary issue to moving into deeper water would be cost.…”

“…The current maximum costeffective water depth for fixed-bottom substructures is estimated at around 60 m, beyond which the amount of material required becomes cost-prohibitive. NREL estimates the current cost-effective water depth limit for floating substructure technologies is around 1,300 m, but does not represent a hard technology limit (Beiter et al 2020;Musial et al 2021a;Shields et al 2021b). Industry practitioners agree that floating wind systems in deeper waters beyond 1300-m are technically feasible provided the seabed slopes are not steep, and that the primary issue to moving into deeper water would be cost.…”

“…NRWAL is an open-source version of NREL's Offshore Regional Cost Analyzer (ORCA) model (Beiter et al 2016) designed to be easy to update based on current offshore wind cost trends and local conditions. The NRWAL/ORCA framework of offshore wind spatial cost relationships has been used for regional offshore wind cost assessments in Hawaii, Oregon, California, Maine, and the Gulf of Mexico (Shields et al 2021b;Musial et al 2021a;Beiter et al 2020;Musial, Beiter, and Nunemaker 2020;).…”

“…A summary of the major line items and how they are derived is provided in Table 9. An input-output flow diagram for NRWAL is provided in Figure 28 based on Shields et al (2021b). NRWAL assumes a standard rate of $1,300/kW for the wind turbine procurement cost (e.g., blades, tower, and nacelle assembly).…”

“…To represent offshore wind plant layouts, we assumed a simplified square grid layout with turbine spacing expressed in terms of number of turbine rotor diameters (D). A spacing of 7D is used, matching recent NREL cost analyses (Shields et al 2021b;Musial et al 2021a;Beiter et al 2020).…”