This report describes a three-bladed, upwind, variable-speed, variable blade-pitch-to-feather-controlled multimegawatt wind turbine model developed by NREL to support concept studies aimed at assessing offshore wind technology.

/pdf/definition-of-a-5-mw-reference-wind-turbine-for-offshore-1we0gw6e7j.pdf

Definition of a 5-MW Reference Wind Turbine for Offshore System Development

This report describes the development, verification, and application of a comprehensive simulation tool for modeling coupled dynamic responses of offshore floating wind turbines.

/pdf/dynamics-modeling-and-loads-analysis-of-an-offshore-floating-1vpwpvvxfj.pdf

Dynamics Modeling and Loads Analysis of an Offshore Floating Wind Turbine

This model intends to provide projections of the impact on cost from changes in economic indicators such as the Gross Domestic Product and Producer Price Index.

/pdf/wind-turbine-design-cost-and-scaling-model-1z37erfpxv.pdf

Wind Turbine Design Cost and Scaling Model

Summary
1. The evidence for anthropogenically induced climate change is overwhelming with the production of greenhouse gases from burning fossil fuels being a key driver. In response, many governments have initiated programmes of energy production from renewable sources.

2. The marine environment presents a relatively untapped energy source and offshore installations are likely to produce a significant proportion of future energy production. Wind power is the most advanced, with development of wave and tidal energy conversion devices expected to increase worldwide in the near future.

3. Concerns over the potential impacts on biodiversity of marine renewable energy installations (MREI) include: habitat loss, collision risks, noise and electromagnetic fields. These factors have been posited as having potentially important negative environmental impacts.

4. Conversely, we suggest that if appropriately managed and designed, MREI may increase local biodiversity and potentially benefit the wider marine environment. Installations have the capacity to act as both artificial reefs and fish aggregation devices, which have been used previously to facilitate restoration of damaged ecosystems, and de facto marine-protected areas, which have proven successful in enhancing both biodiversity and fisheries.

5. The deployment of MREI has the potential to cause conflict among interest groups including energy companies, the fishing sector and environmental groups. Conflicts should be minimized by integrating key stakeholders into the design, siting, construction and operational phases of the installations, and by providing clear evidence of their potential environmental benefits.

6. Synthesis and applications. MREI have the potential to be both detrimental and beneficial to the environment but the evidence base remains limited. To allow for full biodiversity impacts to be assessed, there exists an urgent need for additional multi and inter-disciplinary research in this area ranging from engineering to policy. Whilst there are a number of factors to be considered, one of the key decisions facing current policy makers is where installations should be sited, and, dependent upon site, whether they should be designed to either minimize negative environmental impacts or as facilitators of ecosystem restoration.

https://besjournals.onlinelibrary.wiley.com/doi/epdf/10.1111/j.1365-2664.2009.01697.x

Marine renewable energy: potential benefits to biodiversity? An urgent call for research

Two different simulation models for integrated dynamic analysis of floating offshore wind turbines are described and compared with model scale experiments for the Hywind concept for floating offshore wind turbines. A variety of both environmental conditions and wind turbine control schemes are tested. A maximum power control strategy is applied for wind velocities below the rated wind speed for the wind turbine, while a constant power control strategy is achieved by controlling the rotor blade pitch for wind velocities above rated wind speed. Conventional rotor blade pitch control for wind velocities above rated wind speed introduces negative damping of the tower motion. This results in excitation of the natural frequency in pitch for the tower and may lead to unacceptable tower motions. Active damping of the undesirable tower motions is obtained by an additional pitch control algorithm based on measurement of the tower velocity.Copyright © 2006 by ASME

Integrated dynamic analysis of floating offshore wind turbines

This paper provides a general technical description of several types of floating platforms for wind turbines. Platform topologies are classified into multiple- or single-turbine floaters and by mooring method. Platforms using catenary mooring systems are contrasted to vertical mooring systems and the advantages and disadvantages are discussed. Specific anchor types are described in detail. A rough cost comparison is performed for two different platform architectures using a generic 5-MW wind turbine. One platform is a Dutch study of a tri-floater platform using a catenary mooring system, and the other is a mono-column tension-leg platform developed at the National Renewable Energy Laboratory. Cost estimates showed that single unit production cost is $7.1 M for the Dutch tri-floater, and $6.5 M for the NREL TLP concept. However, value engineering, multiple unit series production, and platform/turbine system optimization can lower the unit platform costs to $4.26 M and $2.88 M, respectively, with significant potential to reduce cost further with system optimization. These foundation costs are within the range necessary to bring the cost of energy down to the DOE target range of $0.05/kWh for large-scale deployment of offshore floating wind turbines.

/pdf/feasibility-of-floating-platform-systems-for-wind-turbines-1dvlxzwwx0.pdf

A. Boone

Papers

Feasibility of Floating Platform Systems for Wind Turbines: Preprint