Advances in wind assessment technology are driven by the pursuit of higher accuracy resource measurements to manage project risk. Emerging trends include using more met towers with additional sensors and remote sensing technologies like SODAR and LIDAR. These provide complementary data to traditional tower measurements and can measure winds at hub heights and beyond. The industry is moving towards best practices like higher towers, more sensors per tower, and strict protocols to lower measurement uncertainty for financing large wind farms with higher turbines.

1. Advances in Wind Assessment Technology:
Industry Pursuit of Higher Resource
Measurements

2. Presentation Overview
• Wind Resource Assessment (WRA)
o Common systems and practices
o Drivers
o Limitations
o Advances
• Summary

3. WRA – Measurement systems and common
measurement practices
• Lattice or tilt-up tubular
• Existing comm towers
Why measure?
• Reliable data loggers
• Robust, about
Gather dataaccurate wind speed
the sensors with
resource
• Robust = durable
objective to sensor is both
• Ideal reduce
uncertainty and durable
accurate
(manage risk)

4. WRA – Measurement systems and common
measurement practices
• More sensor heights and sensor redundancy
o Maximize wind shear characteristics
o Maximize wind rose coverage
•Variety of sensors
o Pairing of 3-cup anemometers, different brands
o NRG #40C
o P2546A WindSensor
o IEC classification, calibration, cost
o Vertical wind speed sensors more widely used

5. WRA – Measurement systems and common
measurement practices
• Data loggers
o 1-second sampling, 10 minute averaging =
worldwide industry standard
o Increase in data logger sensor capacity
o More sensors require more channels
• More automation
o Data transfer from site automated through
cellular or satellite communication services

6. WRA – Measurement systems and common
measurement practices
TREND
– More sensors and variety of sensors

7. Wind Resource Assessment - LIMITATIONS
• Tower based measurements rarely located precisely
where wind turbines are constructed
• High error in hub height shear extrapolations
• Higher, hub height met towers are expensive structures
requiring concrete foundations
o Cannot be moved once constructed
• Anemometers are fixed or static – only measure a
relatively small, fixed point in time
o Not capable of measuring the complete area utilized by the
wind turbine blades

8. WRA - LIMITATIONS
• Wind turbine maximum blade tip height is not hub height

9. Wind Resource Assessment - DRIVERS
• Larger scale wind farms
• Larger scale wind turbines
o 80m typical though advancing to higher towers some regions
• Higher finance requirements
o We are entering the era of the $1B wind farm
• Lowering of acceptable measurement
$
uncertainty
o Wind turbine manufacturers want to know
more about the resource
–Understand Potential for Significant Destruction
(PSD)
– Protect manufacturer reputation
– Underwriters wind turbine warranty terms
– Correct specification of wind turbine for wind
regime
o Wind farm developers and owners want to know more about the
resource to improve their understanding of project risk

10. WRA - ADVANCES
Remote sensing technologies and the wind industry
o SODAR – SOund Detection And Ranging
o LIDAR – LIght Detection And Ranging

11. WRA - ADVANCES
Remote sensing technologies and the wind industry
• Can be moved around easily
• Are especially effective when used in combination with met
towers (complimentary)
• Can be set up and measuring within minutes
• Measure to maximum blade tip height and beyond (200m+)
• Are also useful AFTER the wind farm is constructed
• Power performance verification
• Operations – grid integration, forecasting
• Wind turbine site suitability studies
• Can be located close to met towers
• LIDAR unaffected by precipitation events (rain, snow)
RS – Essential equipment
for successful wind farm operations?

12. WRA - ADVANCES
Other important incremental advances in tower-based
measurements
• More towers, more sensors
• Increased use of sensor redundancy
• Increased variety of sensors
o Not all sensors measure the same
o Increasing use of vertical wind sensors
• Stricter attention to sensor mounting
• Use of fixed and mobile towers AND remote sensing
o Maximizes understanding of spatial variability without
proportionally increasing cost
o Known as ‘Fixed and Mobile Tower’-methodology (FMT) *
* WindLogics, Haynes, Scott and Moon, Dennis, Understanding Wind Variability in Complex Terrain –
Applying the Fixed and Mobile Tower (FMT) Technique – CanWEA 23rd Annual Conference, 10/2/2007.

13. SUMMARY
EMERGING TRENDS IN WRA
• TOWERS
• More towers are better than less, especially in more
complex terrain
o Met towers are relatively low-cost
– Measure twice – cut once …
– “You can fix a gearbox, you cannot fix the wind”
• Industry using higher met towers with more sensors
o 60m is typical at early measurement stages
• Higher wind turbines and much more attention to
lowering overall measurement uncertainty
• Stricter attention to sensor mounting and documentation
• More sensors and more sensor variety

14. SUMMARY
• Budget constrained projects can utilize FMT
o Technique claims reduced cost without compromising
study outcome
• Using advanced WRA methodologies, such as RS, is in
your best interest
o Supports better financing and warranty terms
o Improves confidence in profitability of the Project

15. About NRG Systems
• Manufacturing
plant located in
Hinesburg, VT USA
• 30+ years – wind
industry experience
• Worldwide logistical
capacity
• ‘Lean’
manufacturing
production
• Sustainable
business values and
commitment
NRG Systems manufacturing plant, Hinesburg, Vermont

16. Thank you
Questions?
David Simkins
Strategic Business Development
NRG Systems, Inc.
davids@nrgsystems.com
802-482-2255
www.nrgsystems.com