Offshore Wind Met-ocean Data Gaps:

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Jared Lamb
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1 Workshop on Offshore Wind Energy Standards & Guidelines June 2014, Arlington, VA Offshore Wind Met-ocean Data Gaps: Assessing External Conditions for Offshore Wind Design in a Data-scarce Environment Matthew V. Filippelli Lead Engineer AWS Truepower LLC Albany, NY

2 Motivation Coordinated efforts are needed to mitigate or eliminate data-related offshore wind technical/market barriers through a process involving public-private, multistakeholder collaboration that addresses offshore metocean assessment, design condition definition, standards, and operational industry needs. To illustrate the link between gaps in meteorological and ocean (met-ocean) instrumentation, data and modeling to the plant design processes and relevant international standards and guidelines.

3 Overview Introduction Key Parameters Instrumentation & Measurements Data & Analyses Modeling Summary

Introduction High-quality met-ocean data and model results are essential to characterize the inputs to offshore wind design processes in the US.

4 Introduction High-quality met-ocean data and model results are essential to characterize the inputs to offshore wind design processes in the US. There is a scarcity of key atmospheric/ocean measurements that can add both uncertainty and cost to the wind design process. Current industry measurement and modeling practices can be effective, but will benefit from coordinated efforts on regional and national scales. Collaboration with met-ocean data stakeholders is essential.

5 Typical Met-ocean Data Users Utilities/Grid Operators Government Agencies & Regulators Applications Developers and OEMs Project Siting & Permitting Energy Projections Technology Design & Validation Facility Design Financing Construction Operations & Site Safety Forecasting Banks, Investors & Insurance Providers Technical Experts & Researchers Facility Design affects a broad array users and associated applications 0&M Providers and Human Safety Marine Engineers & Construction Firms

6 External Conditions - Background The process of characterizing external (met-ocean) conditions for offshore wind plant design is often not distinguished from conducting a wind resource assessment or calculating inputs to an energy yield analysis These are related tasks with overlaps of parameters and campaign characteristics, but have different requirements and calculation methods, and occasionally different endusers of the data

7 External Conditions - Background Wind Resource and Energy Yield: focus upon detailed atmospheric characterization and system performance parameters over a year evaluation period Best practices & guidelines; no standards (yet) Plant Design: focus upon combined meteorological and ocean parameters to address system safety and functionality based upon design load cases and return periods (e.g. 1, 50, 100, 500 years) Specified in Design Standards and Guidelines Both uses are important and need to be considered during project and campaign design; focus will be on the latter

8 Design Standards and Guidelines Provide framework offshore wind facility design, codified from consensus and industry best practices Include guidance for defining key external / environmental conditions Under development to better represent US Offshore conditions

Primary Data Parameters Current and Historical ATMOSPHERE WIND: 200 m Shear, Veer, Turbulence Gusts (3- & 5-sec; 50, 100 yr RP) ATMOSPHERIC STATE MABL Characterization T,

9 Primary Data Parameters Current and Historical ATMOSPHERE WIND: 200 m Shear, Veer, Turbulence Gusts (3- & 5-sec; 50, 100 yr RP) ATMOSPHERIC STATE MABL Characterization T, P, RH, Precip, Solar, Cloud Stability, Low Level Jets CLIMATOLOGY Means, Distributions, Extremes Time Series Hurricanes, Icing, Lightning Source: NREL Image courtesy NREL

What does this mean, Specifically? Key Design Parameters outlined in Annex A of IEC61400-3 Exact inputs vary by designer, examples include: Max 10 min. and 3 sec.

10 What does this mean, Specifically? Key Design Parameters outlined in Annex A of IEC Exact inputs vary by designer, examples include: Max 10 min. and 3 sec. speed at Hub height, Hurricane and non-hurricane on 1, 50, 100, 500, 1000 year return periods; Wind shear exponent (α) long-term mean, longterm mean for wind speeds >20 m/s, value at extreme speeds, mean and >20 m/s values by direction sector; Mean Turbulence Intensity (TI) at Hub height, Standard deviation (σ) of TI, Characteristic TI, 15 m/s, Mean and σ TI by wind speed bin, effective TI by wind speed bin; Wind speed frequency and direction distributions; Min, Max and Average hub temperature, pressure and density; density at max gust Excerpted from IEC , ed Annex A

11 Primary Data Parameters Current and Historical Water Surface and Subsurface HYDROGRAPHIC Wave Height, Freq., Dir. Surface Currents and Profiles WATER STATE Water surface temp and profile Salinity, chemistry, and Ice BIOLOGIC and BOTTOM Marine growth rates Bottom soil type Source: NREL Coincident Atmospheric and Ocean Conditions Image courtesy NREL

12 What does this mean, Specifically? Key Design Parameters again outlined in Annex A of IEC Exact inputs vary by designer, examples include: Storm-peak (hurricane and non-hurricane) significant wave height, wave direction, and spectral-peak wave period (1, 50, 100, 500, 1000 yr returns) 10 min mean surface (10 m MSL) wind speed, surface current velocity, subsurface current profile, significant wave height and mean zer0- crossing, Min. & max. still water level - surge+tide (1, 50, 100, 500, 1000 yr returns) Excerpted from IEC , ed Annex A Joint probability distribution of mean wind speed conditioned on significant wave height by wind direction sector probability distribution of hub-height wind direction and wave direction

Filling in the Blanks With the key design parameters identified, it s instructive to review the methods and resources available to define them in US waters Examining the assessment

13 Filling in the Blanks With the key design parameters identified, it s instructive to review the methods and resources available to define them in US waters Examining the assessment processes and options in the framework described by DOE Instrumentation, Data, and Modeling helps provide insight into gaps and needs Met-ocean Assessment Instrumentation + Standards

Instrumentation Available Measurements Despite excellent

address required design parameters Instrumentation

reporting (hub height data) Few fixed offshore

exponent) Diverse instrumentation suites and measurement

14 Instrumentation Available Measurements Despite excellent resources, very limited existing instrumentation to address required design parameters Instrumentation Challenges and Gaps: Low elevation monitoring / reporting (hub height data) Few fixed offshore observations; nearly zero with multiple levels (shear exponent) Diverse instrumentation suites and measurement methods (direct and remote) Sensors not configured for key parameters (TI) U.S. IOOS Data Catalog and Asset Viewer Snapshot Images courtesy NOAA NDBC

15 Instrumentation Working with Scarcity Leverage developer s purpose-deployed stations and/or networks Depending upon monitoring approach, this may still require significant analysis For preliminary design work, or in areas with very limited resources, integrated approach synthesizing regional measurements, modeling, analytical approaches and experience Shear exponents: derived from regional observations where available, and mesoscale modeling; Turbulence Intensity: numerical models or analytical methods, validated regionally; Max Wind Speed Values: Integrating shear analyses, regional data and extreme event modeling (atmospheric and wave modeling); Both valid and effective approaches, but can have significant cost and timing implication (first approach), or greater uncertainty in the derived results (second approach).

Instrumentation Filling the Gaps Dedicated,

project site An expanded and enhanced national

design (and resource assessment) input parameters

instrumentation deployment and/or leveraging of

facilities Validation of emerging monitoring

16 Instrumentation Filling the Gaps Dedicated, multi-year measurements on or adjacent to a project site An expanded and enhanced national offshore monitoring network, with a focus on key design (and resource assessment) input parameters Public-private collaboration on new instrumentation deployment and/or leveraging of existing assets One or more offshore reference facilities Validation of emerging monitoring technology with a focus on design parameters, e.g. TI & gusts Source:

Data Available Resources Long-term and extreme weather data sets have similar challenges to instrumentation: scarce information at hub height, limitations on

multi-height wind measurements (shear) Data parameters vary in availability and calculation method by instrumentation package Key parameters not observed or

17 Data Available Resources Long-term and extreme weather data sets have similar challenges to instrumentation: scarce information at hub height, limitations on key metocean parameters Additional Data Challenges and Gaps: Inconsistent time scales with required analyses (Max 10 min average, max gust) Limited multi-height wind measurements (shear) Data parameters vary in availability and calculation method by instrumentation package Key parameters not observed or calculated (TI, current profiles, temperature profiles, marine growth, water chemistry) Some data sets do not extend offshore (e.g. hail) NOAA NDBC (above) and NOAA NHC (right)

18 Data Filling the Gaps Working with disparate time scales, data sources, and libraries can typically be accommodated with appropriate analyses, guidance from the standards and modeling support Gaps in some key parameters require new measurements to be initiated Parameter and documentation (meta-data) standardization would help facilitate analysis and integration of data sets High quality, targeted measurements coupled with modeling can measurements

Modeling Key integration and analysis tools Spatial Scales and Interfaces for Flow Modeling Sophisticated approaches exist to integrate and predict met-ocean conditions Defining the atmospheric

19 Modeling Key integration and analysis tools Spatial Scales and Interfaces for Flow Modeling Sophisticated approaches exist to integrate and predict met-ocean conditions Defining the atmospheric boundary layer structure & dynamics (e.g. shear, TI) Understanding land-sea and air-sea interactions; extreme events (e.g. gusts) Extrapolating and integrating sparse data in space and time Simulating wake generation, meandering, interactions and impacts Key gaps are validation data and further development

Modeling Filling the Gaps Models will benefit most from additional data for ingestion and validation, standardized measurements & data quality, and data sharing Modeling of extreme event

20 Modeling Filling the Gaps Models will benefit most from additional data for ingestion and validation, standardized measurements & data quality, and data sharing Modeling of extreme event characteristics and return periods is advancing Model coupling (to capture complex flow across spatial scales and environments is improving Collaboration between industry and research community is needed to ensure definition of user needs and widely useful results See DOE workshop report for more background:

Standards Filling the Gaps New IEC Standard initiated to address site characterization: IEC 614

21 Standards Filling the Gaps New IEC Standard initiated to address site characterization: IEC Ed.1.0: Assessment of site-specific wind conditions for wind power stations Process just initiated; scope addresses site assessment methods, reporting procedures and uncertainty calculations Potentially influence related design standards to better address uncertainty / distribution on inputs In the interim, other guidance documents available to address monitoring and analysis

22 Summary Offshore wind plant design requires the detailed characterization numerous met-ocean parameters, specified in design standards and guidelines Instrumentation, data and modeling gaps complicate the assessment of external design conditions (and resource assessment) Dedicated site assessment campaigns (including measurements and modeling) and expert analysis can bridge these gaps now; however, coordinated steps on regional and national scales would help reduce market barriers. Strategies for bridging met-ocean data and methods gaps require public/ private investment, technical innovation, and cooperation among key stakeholders.

23 Questions or comments? x 1015 THANK YOU

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