Comparison of API & IEC Standards for Offshore Wind Turbine Applications in the U.S. Atlantic Ocean: Phase II - March 9, 2009 - September 9, 2009

Technical Report · Tue Jan 01 04:00:00 EST 2013

DOI:https://doi.org/10.2172/1067926· OSTI ID:1067926

Jha, A. ^[1]; Dolan, D. ^[1]; Gur, T. ^[1]; Soyoz, S. ^[1]; Alpdogan, C. ^[1]

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1. MMI Engineering, Houston, TX (United States)

The National Renewable Energy Laboratory (NREL) contracted MMI Engineering to conduct Phase II of the Joint Industry Project on Comparison of two design standards for offshore wind turbines (OWTs) in the United States Outer Continental Shelf waters. The two standards were the American Petroleum Institute (API) RP – 2A Recommended Practice for Planning, Designing, and Constructing Fixed Offshore Platforms and the International Electrotechnical Commission (IEC) 61400-3 Design Requirements for Offshore Wind Turbines. In Phase I, two structure types (a monopile and a tripod) were studied at two sites – offshore Texas at 24-m water depth and offshore Massachusetts at 15-m water depth. This study provided insights into the loads imposed on the structures caused by wind and ocean forces, and also provided insights into the strength (capacity) of the structures subject to these loads. The resulting reliability (annual failure probability for ultimate strength) for the two structures at the two sites were generally governed by turbine and blade resonance avoidance for designing the structure, and not by ultimate strength needs to resist extreme loads. The conclusions drawn from Phase I were based on these limited numbers of case studies. This limitation prompted the need to conduct this second phase to study two new designs, the monopile and a jacket (space frame) substructure, at the same site where ultimate strength would likely also influence design and resonance avoidance. The site selected for Phase II was the offshore Massachusetts site, but with a water depth of 25 m (instead of 15 m as in Phase I). This selection permitted the use of the same meteorological and oceanographic (metocean) parameters, with the breaking wave criteria altered as a result of the increased water depth.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Wind Energy Technologies Office
• DOE Contract Number: AC36-08GO28308
• OSTI ID: 1067926
• Report Number(s): NREL/SR--5000-49688
• Country of Publication: United States
• Language: English

Related Subjects

17 WIND ENERGY
OFFSHORE WIND TURBINES
STANDARDS
WIND TURBINE DESIGN
Wind Energy