Design Studies for Deep-Water Floating Offshore Vertical Axis Wind Turbines

Abstract

Deep-water offshore sites are an untapped opportunity to bring large-scale offshore wind energy to coastal population centers. The primary challenge has been the projected high costs for floating offshore wind systems. This work presents a comprehensive investigation of a new opportunity for deep-water offshore wind using large-scale vertical axis wind turbines. Owing to inherent features of this technology, there is a potential transformational opportunity to address the major cost drivers for floating wind using vertical axis wind turbines. The focus of this report is to evaluate the technical potential for this new technology. The approach to evaluating this potential was to perform system design studies focused on improving the understanding of technical performance parameters while looking for cost reduction opportunities. VAWT design codes were developed in order to perform these design studies. To gain a better understanding of the design space for floating VAWT systems, a comprehensive design study of multiple rotor configuration options was carried out. Floating platforms and moorings were then sized and evaluated for each of the candidate rotor configurations. Preliminary LCOE estimates and LCOE ranges were produced based on the design study results for each of the major turbine and system components. The major outcomes of this study are a comprehensive technology assessment of VAWT performance and preliminary LCOE estimates that demonstrate that floating VAWTs may have favorable performance and costs in comparison to conventional HAWTs in the deep-water offshore environment where floating systems are required, indicating that this new technology warrants further study.

System Levelized Cost of Energy Analysis for Floating Offshore Vertical-Axis Wind Turbines

“…The optimal VAWT blade architecture was analyzed during the previous design studies performed by Sandia, identified as the system with the most potential to reduce blade cost for the same blade radius and rotor swept area [1]. The design studies analyzed two primary design types, the classic Darrieus VAWT along with V-VAWT designs.…”

“…The design and cost estimation for the platform, mooring, and installation represent a significant body of work performed as part of this study, with greater detail provided in Section 5 and Reference [2]. The VAWT rotor design study and optimization utilized in this study were based on findings from previous work summarized in Section 2 and Reference [1]. The remaining cost components are established within this report from literature review and using models developed by the National Renewable Energy Laboratory.…”

“…The first phase was conducting design studies using a variety of rotor architectures and platform types to assess the feasibility of the technology at this scale. The design studies, methodologies, and findings are described in the full report [1]. Phase two of the project was performed to gain more confidence in the system cost analysis, with a focus on the platform design and cost estimate.…”

Parked and Operating Loads Analysis in the Aerodynamic Design of Multi-megawatt-scale Floating Vertical Axis Wind Turbines

“…As wind energy costs have come down, the opportunity to fill this need by advancing the potential of wind turbine technology is at an all-time high as a part of the initiative to reduce greenhouse gas emissions and provide greater generation by renewable sources. The wind energy community has been mostly focused on Horizontal Axis Wind Turbines (HAWTs), but recently another type of turbine named Vertical Axis Wind Turbines (VAWTs) (Bhutta et al (2012); Sutherland et al (2012)) have garnered interest especially in offshore locations (Griffith et al (2018); Möllerström et al (2016)). VAWTs have some distinct advantages over HAWTs because of their low center of gravity (c.g), absence of pitch and yaw mechanism, directional independence to wind and low sound emission (due to low operational TSR) (Griffith et al (2018); Möllerström et al (2016)).…”

A review of state-of-the-art in torque generation and control of floating vertical-axis wind turbines

“…2a). Several different rotor types [64] and floating system configurations [25] have been evaluated for a floating VAWT system [29,30]. Meanwhile, research on VAWTs is conducted on a global scale at universities, and some issues do not have a definite answer.…”