Transcript Measurement and model requirements for offshore wind energy

Measurement and model
requirements for offshore wind
energy
Larry Atkinson
Jose Blanco
Virginia Coastal Energy Research Consortium
Old Dominion University
Offshore wind farms have a good
chance of being built
• They will be large
and there will be
many of them.
• The Minerals
Management Service
has set interim rules
for planning,
installation,
operation, safety
and removal.
Photo from NREL
Pathways for offshore technology
(Musial, 2007)
Outline
• Status of wind farm development off the NE
United States
• Information requirements for
– Engineering
– Power management
– Safety
– Environmental related needs
• What assets do we now have for observing
• Conclusions
Status for Northeast US
• There are no wind turbines in either
state or federal waters in the US.
• Pre-lease activities starting – state by
state ‘task forces’ being formed
• Met towers will be proposed soon for
locations off VA, DE, NJ, and RI.
– Note met towers must be to hub
height and make direct
measurements.
– Proprietary data issues being
addressed
• MMS funding literature reviews and
synthesis.
Cape Winds Met Tower
For example - off Virginia the state
is identifying possible locations
From VCERC presentations
Required Data For Offshore Sitting & Design
Wind - Waves – Currents
• Avg. Speeds – annual, monthly,
diurnal (at hub height)
• Speed Frequency Distribution
• Wind Shear
• Turbulence Intensity
• Wind Direction Rose
• Extreme Gusts & return periods
• Coincident Sea-State Conditions
• Water and air temperatures
• Aerosol production - corrosion
• Waves spectra and return period
• Extreme wave and wind events hurricanes, northeasters,
thunderstorms
From NREL report
More detail needed on wind
classes – example off Virginia
How real are the
details in these wind
maps?
From NREL report and website
Boundary Layer Data Needed
recommendations from NREL Report
• Wind characteristics at coastal and marine locations
need to be evaluated on a case-by-case basis.
• Variations in the structure of marine boundary layers are
significant and require further detailed study.
• A key component of future studies is additional
measurement data from 70 to 100 m above the surface.
• Tall-tower measurements and remote sensing
instrumentation will be crucial to increase the knowledge
of marine boundary layer structure and its effect on the
viability of wind energy projects in coastal and marine
areas.
NREL 2007 “Coastal and Marine Tall-Tower Data Analysis: Preprint”, Schwartz,
Elliott and Scott
Information requirements
Power management
• Local gust and turbulence detection and
prediction
• Larger scale wind field prediction for power
management.
• Predicting shut down conditions
From AWEA Report
Offshore Wind Working Group 3 April 2009
• Predict dynamic forces and motions acting on turbines
• Predict loads and dynamic responses of the coupled wind
turbine and support structure when subjected to combined
stochastic wave and wind loading.
• Impact of floating debris and ice and from marine growth
buildup on the substructure.
From http://www.iopara.ca
Information Requirements
Safety and Operations
• Wind, wave and current observations and
predictions
• Icing
• Visibility
From Siemans/StatoilHydro
Information requirements
Environmental
• Bird migration (NEXRAD
used for bird mapping)
• Factors related to
bird/bat turbine
interaction
• Fish aggregation
• Effect on wave and
current patterns
“Avian collision risk at an offshore wind farm” Desholm and Kahiert, Biol. Lett., doi:
10.1098/rsbl.2005.0336.
Current observing assets in the
water
Most wind farms will be
around 12 miles offshore.
Observing stations are
typically coastal or mid to
outer shelf.
Thus wind farms are going
into areas not well sampled.
Sea breeze is an issue.
Buoys and a few towers
• Towers provide
data
approaching hub
height but there
are few of them
• The are more
buoys (less than
10 in the area).
Remote Sensing of ocean winds
• Remote sensing winds ‘speculative’ for
offshore wind farms. (Pryor et al 2004)
• Must be improved as spatial coverage needed
and in situ cannot cover.
Integrating wind farms to even out
power production
• Visualize wind farms
from Cape Hatteras to
Cape Cod
• How to manage the
power output of the
system as a whole with
the multiple power
companies in the
region.
• Predictions needed to
manage power market.
Final Thoughts
• We will need better nowcasts and forecasts of
offshore wind and waves at finer time and space
scales.
• Our understanding of the marine boundary layer and
sea breeze in coastal waters must improve.
• AMS and AWEA might (if they are not already)
collaborate on offshore renewable energy issues.
• There will be an opportunity for industry to develop
new business.