Process-based balance of system cost modeling for offshore wind power plants in the United States

Abstract

This paper describes the development of a process-based and open-source balance of system cost model that provides the capability to evaluate both existing and novel offshore wind technologies. Individual design and installation steps are represented with bottom-up engineering models that compute times and costs associated with the process; furthermore, operational constraints are assigned to each process so that delays caused by weather and presence of marine mammals may be accounted for in the overall project timeline. The model structure, assumptions, inputs, and results are vetted with industry partners and compared against actual projects for validation. Installation times show reasonable agreement with real data. Project cost sensitivities are investigated to compute the system-level impact of different design choices. First, individual vessel efficiencies are computed for varying numbers of installation vessels and weather time series to show the diminishing returns of more than two feeder barges. Then, array cable capital costs and installation times are determined for a representative project with different turbine sizes. These values quantify the cost-benefit tradeoffs and show a net-cost savings of decreasing numbers of turbines, increased turbine spacing, and fewer turbine terminations. These results demonstrate that the balance of system model features the accuracy, functionality, and accessibility to serve as the foundation for a wide range of analyses to identify cost reduction potentials for offshore wind energy in the United States.

2019 Cost of Wind Energy Review

“…Offshore wind turbines have increased in size in the recent past and manufacturer announcements suggest that this trend will continue (Shields and Nunemaker 2020). Ten-MW turbines are commercially available today, with larger turbines currently in different phases of market and technology development (MHI Vestas 2018).…”

The Cost of Floating Offshore Wind Energy in California Between 2019 and 2032

“…Recent LCOE reductions can, in part, be attributed to the use of larger offshore-specific wind turbines (Musial et al 2020b). Current market data and NREL modeling efforts (Shields and Nunemaker 2020) indicate that the trend toward larger machines is likely to continue (Musial et al 2020b). MHI Vestas has released its 9.5-MW and 10-MW wind turbines to the offshore market with the first commercial deployments well underway (MHI Vestas 2018).…”

“…ORBIT is based on systems-level engineering models that calculate the durations of individual installation processes using project geospatial data; vessel and component data sheet specifications; component cost data; and industry standards. Installation times and costs calculated in ORBIT scale with variables such as project size, turbine rating, site location, substructure technology, and vessel selection (Shields and Nunemaker 2020). The effect of turbine size is modeled for an assumed increase in turbine rating from 8 MW (2019 COD) to 10 MW (2022 COD), 12 MW (2027 COD), and 15 MW (2032 COD) (Table 2).…”

2020 Cost of Wind Energy Review

“…Offshore wind turbines have increased in size in the recent past and manufacturer announcements suggest that this trend will continue (Shields and Nunemaker 2020). For example, 9.5-MW turbines have been installed, with larger turbines currently in different phases of market and technology development (REVE 2019).…”